Advances in personalized medicine to treat Autism/IDD – Rett syndrome as an example. Also, Piperine to upregulate KCC2, but what about its direct effect on GABAa receptors?

 

Source:  https://www.cell.com/neuron/pdf/S0896-6273(21)00466-9.pdf

Today’s post is drawn from a workshop I am invited to present at an autism conference in Abu Dhabi.

I decided to talk about advances in personalized medicine – no surprise there.  Since I have 2 ½ hours, I thought I will need some interesting examples to maintain the audiences interest.  One such topic is going to be Rett syndrome.

I regard Rett syndrome and all the other such syndromes in this blog as “single gene autisms” (monogenic autism).  If you apply the American DSM classification, from 2013 onwards Rett syndrome is no longer part of autism.  Hopefully there are no such purists attending in Abu Dhabi. 

Two gene therapies for Rett syndrome are currently undergoing human trials and one drug therapy has been FDA approved.  This looks very encouraging, so let’s dig a little deeper.

Rett syndrome can present with a wide range of disability ranging from mild to severe. 

Rett syndrome is the second most common cause of severe intellectual disability after Down syndrome.

Other symptoms may include:

•      Loss of speech

•      Loss of purposeful use of hands

•      Loss of mobility or gait disturbances

•      Loss of muscle tone

•      Seizures or Rett “episodes”

•      Scoliosis

•      Breathing issues

•      Sleep disturbances

•      Slowed rate of growth for head, feet and hands

Here are the new therapies: 

TSHA-102: This gene therapy, developed by Taysha Therapeutics, is a gene replacement therapy that aims to deliver a functional copy of the MECP2 gene to brain cells.  It utilizes an AAV-9 virus to carry the miniMECP2 gene product into cells for the body to produce more MeCP2 protein, which is deficient in Rett syndrome. As of February 2024, Taysha completed dosing for the first cohort (low dose) in their REVEAL Phase 1/2 adolescent and adult trial in Canada, with positive interim data on safety. They are also conducting trials in the US for both pediatric and adolescent/adult populations.

NGN-401: This gene therapy, by Neurogene Inc., employs a different approach. It uses an AAV9 vector to deliver a regulated version of the MECP2 gene called EXACT. This technology aims to control the amount of MECP2 protein produced by the gene, mitigating the risk of overproduction. NGN-401 is currently in a Phase 1/2 trial for girls with Rett syndrome aged 4 to 10 years old.

Daybue (trofinetide)

Daybue is the first and only FDA-approved treatment specifically for Rett syndrome in adults and children two years of age and older. It is not a gene therapy, but rather a medication taken orally.

The optimistic AI generated view:

Here's a breakdown of Daybue for Rett syndrome:

• Mechanism: The exact way Daybue works in Rett syndrome isn't fully understood, but it's believed to target neuroinflammation and support synaptic function.
• Dosage: The recommended dose is based on the patient's weight and is taken twice daily, morning and evening, with or without food.
• Administration: Daybue comes as an oral solution and can be taken directly or through a gastrostomy tube if swallowing is difficult.
• Efficacy: Studies have shown that Daybue can improve symptoms of Rett syndrome, including reducing scores on the Rett Syndrome Behavior Questionnaire (RSBQ) and showing improvement on the Clinical Global Impression-Improvement (CGI-I) scale.
• Side Effects: The most common side effects of Daybue are diarrhea and vomiting. Weight loss can also occur in some patients. It's important to consult with a healthcare professional for monitoring and managing any potential side effects.

Daybue is an expensive medication. Here's what we know about the cost:

• List Price: The list price of Daybue is around $21.10 per milliliter.
• Annual Cost: This translates to an estimated average annual cost of around $375,000 for patients.
• Dosage Variability: It's important to note that the dosage of Daybue is based on a patient's weight, so the annual cost can vary depending on the individual.

Insurance and Assistance Programs:

• The high cost of Daybue highlights the importance of insurance coverage. Whether insurance covers Daybue and to what extent will depend on your specific plan.
• The manufacturer, Acadia Pharmaceuticals, offers a copay program called Daybue Acadia Connect. This program may help eligible commercially insured patients pay $0 for their monthly prescription.

What are the parents' groups saying? 

Not as good as you might be expecting for $375,000 a year.

Affordable potential alternatives to Daybue/Trofinetide

Daybue/Trofinetide is the product of decades of research into a growth factor called IGF-1.

It is a complicated subject and as usual the abbreviations can be confusing.

As you will see below there already is an OTC product commercialized by one of the original researchers, Dr Jian Guan.

One Rett syndrome parent, who reads this blog, has trialed cGP and sees a benefit. You rather wonder why the Phelan-McDermid, Pitt Hopkins, Angelman and Prader-Willi parents don’t follow him and splash out 50 USD and make a trial.

 

 

Gene-therapy

Gene therapy is undoubtedly very clever and ultimately will likely be the best therapy.  It still may not be that silver bullet.

To be effective gene therapy needs to be given at a very young age, ideally as a fetal therapy prior to birth. Note that we saw that in the Rett mouse model they gave bumetanide to the pregnant mother just before birth.

Fetal therapy is not a crazy idea and much is already written about it; many pregnancies are terminated because genetic anomalies are detected prior to birth. Down syndrome is the best-known example. Fetal therapy is realistic for some disorders.

Girls with Rett syndrome are often diagnosed first with idiopathic autism and then years later with a more precise diagnosis of Rett syndrome. This is a common experience among readers of this blog.

Classic Rett syndrome 

The average age of diagnosis for this form is around 2.5 years old in the US and 5 years old in the UK.  Why do you think that is?

Research in mouse models has shown that the effect of gene therapy ranges from curative when given extremely young to more limited the later it is given.

Off-target effects

Gene therapy has the potential for off-target effects. This is a significant concern in the field and researchers are actively working on ways to minimize these risks. Here is a breakdown of what off-target effects are and why they matter:

During gene therapy, a modified gene is delivered to target cells with the aim of correcting a genetic defect.

Ideally, the modified gene integrates into the intended location in the genome.

However, there's a chance it might insert itself into unintended locations (off-target sites).

Potential Consequences of Off-Target Effects

Disrupting normal genes at off-target sites could lead to unpredictable and potentially harmful consequences. This could include triggering uncontrolled cell growth, which is a risk factor for cancer.

It can also cause unexpected side effects depending on which genes are accidentally disrupted.

Minimizing Off-Target Effects

Researchers are developing various strategies to improve the accuracy and specificity of gene therapy techniques.

This includes using more precise gene editing tools like CRISPR-Cas9 with optimized guide RNAs to reduce off-target edits.

Additionally, researchers are working on methods to detect and potentially repair any off-target modifications that might occur.

Over-expression of the target gene

Yes, there is a possibility that the replaced gene in gene therapy could overproduce the expressed protein. This can be a potential complication and researchers are working on ways to control the level of protein expression. Here's a breakdown of the concern:

• Gene Dosing: Ideally, gene therapy aims to deliver a functional copy of the gene at the right amount to compensate for the deficiency.
• Overproduction Risks: However, if the delivered gene is too active or multiple copies are inserted, it can lead to overproduction of the protein.

Consequences of Protein Overproduction:

• Overproduction of a protein can disrupt the delicate balance in the cell, potentially leading to cell dysfunction or even cell death.
• In some cases, the protein itself might have harmful effects if present in excessive amounts.

Controlling Protein Expression:

Researchers are developing several strategies to control protein expression in gene therapy:

• Promoter selection: Using promoters that have a weaker switch can help regulate protein production.
• Viral vectors: Engineering viral vectors to control the number of gene copies delivered to cells.
• Inducible systems: Developing gene therapy methods where the expression of the introduced gene can be turned on and off as needed.

The cost of gene therapy

•      Despite the high cost, gene therapy can be a cost-effective treatment for some diseases. This is because it can eliminate the need for lifelong treatment with other medications.

•      Here are some examples of the cost of currently available pediatric gene therapies:

•      Luxturna (gene therapy for Leber congenital amaurosis type 10): $425,000

•      Zolgensma (gene therapy for spinal muscular atrophy type 1): $2.1 million

•      Skysona (gene therapy for adrenoleukodystrophy): $3 million

Piperine to correct KCC2 expression in Rett syndrome?

One key feature of Rett syndrome is impaired cognition.

As regular readers are aware, there are many types of treatable intellectual disability (ID).

One type of treatable ID is caused when the GABA developmental switch fails to occur shortly after birth.  This creates an excitatory/inhibitory imbalance in neurons which impairs cognition and lowers IQ.

The faulty GABA switch is a feature of many types of autism, but far from all of them.

By using pharmaceuticals to lower chloride within neurons, you can compensate for the failure of the GABA switch.

This treatment can be achieved by:

1.     Blocking or down regulating NKCC1

2.     Up regulating KCC2

In the paper below they look at up regulating KCC2

Pharmacological enhancement of KCC2 gene expression exerts therapeutic effects on human Rett syndrome neurons and Mecp2 mutant mice

Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in the methyl CpG binding protein 2 (MECP2) gene. There are currently no approved treatments for RTT. The expression of K⁺/Cl⁻ cotransporter 2 (KCC2), a neuron-specific protein, has been found to be reduced in human RTT neurons and in RTT mouse models, suggesting that KCC2 might play a role in the pathophysiology of RTT.

Injection of KEEC KW-2449 or piperine in Mecp2 mutant mice ameliorated disease-associated respiratory and locomotion phenotypes. The small-molecule compounds described in our study may have therapeutic effects not only in RTT but also in other neurological disorders involving dysregulation of KCC2.

Thus, our data demonstrate that activation of the SIRT1 pathway or the TRPV1 channel enhances KCC2 expression in RTT human neurons.

Treatment with piperine (10 μM), an activator of the TRPV1 channel (51), induced a significant rise in KCC2 expression in cultured human neurons 

We already knew this was likely from earlier research from Ben Ari, see below for a reminder.  Is Piperine an interesting option for those restricted to OTC interventions?

Early alterations in a mouse model of Rett syndrome: the GABA developmental shift is abolished at birth

Genetic mutations of the Methyl-CpG-binding protein-2 (MECP2) gene underlie Rett syndrome (RTT). Developmental processes are often considered to be irrelevant in RTT pathogenesis but neuronal activity at birth has not been recorded. We report that the GABA developmental shift at birth is abolished in CA3 pyramidal neurons of Mecp2-/y mice and the glutamatergic/GABAergic postsynaptic currents (PSCs) ratio is increased. Two weeks later, GABA exerts strong excitatory actions, the glutamatergic/GABAergic PSCs ratio is enhanced, hyper-synchronized activity is present and metabotropic long-term depression (LTD) is impacted. One day before delivery, maternal administration of the NKCC1 chloride importer antagonist bumetanide restored these parameters but not respiratory or weight deficits, nor the onset of mortality. Results suggest that birth is a critical period in RTT with important alterations that can be attenuated by bumetanide raising the possibility of early treatment of the disorder.

One day before delivery, maternal administration of the NKCC1 chloride importer antagonist bumetanide restored these parameters but not respiratory or weight deficits, nor the onset of mortality. Results suggest that birth is a critical period in RTT with important alterations that can be attenuated by bumetanide raising the possibility of early treatment of the disorder.

Treating the mother prior to delivery with bumetanide was a partially effective therapy in the mouse model of Rett syndrome.

Piperine

Bumetanide is cheap and very possibly effective in human Rett syndrome, but it is a prescription drug.

Piperine is an OTC supplement and a compound found in black pepper. By activating the TRPV1 channel it causes an increase in expression of the KCC2 transporter that allows flow of chloride out of neurons. So piperine should lower chloride inside neurons.  Piperine can cross the blood brain barrier, so when taken orally it should have some effect on intracellular chloride.

Piperine is also a positive allosteric modulator of GABA_A receptors

This means that piperine multiplies the effect of whatever GABA is around. This means that in typical people piperine should have anti-anxiety effects.

Piperine was recently found to interact with a previously unknown  benzodiazepine-independent binding site.

Researchers are currently toying with the piperine molecule to try and separate the effect on TRPV1 from the effects on  GABA_A.  They want to create 2 new drugs.

1.     a selective TRPV1 activator

2.     a selective GABA_A modulator (PAM)

Piperine as an alternative or complement to Bumetanide?

One effect of piperine would be great to have (TRPV1 activator) but the second effect would not be helpful (positive allosteric modulator of GABAA).

The question is what is the net effect. Nobody will be able to answer that without a human trial.

I was advised long ago by one drug developer than it is best to focus on reducing flow into neurons via NKCC1, rather than increase its exit by KCC2, because nobody had yet been successful with KCC2; many have tried.  KCC2 plays a key role in neuropathic pain and that is why it has been researched.

Conclusion

We did see years ago that taking coffee with your bumetanide made sense. Coffee contains compounds that are OAT3 inhibitors and slow down the excretion of bumetanide from the body; coffee increases the effect of bumetanide. You can achieve something very similar by just increasing the dose of bumetanide.

Taking black pepper (piperine) with your bumetanide might be good, or might not be. It certainly would be easy to find out. As with Daybue/Trofinetide, the result is likely to vary from person to person. If GABA function, post- bumetanide, is still a bit excitatory amplifying GABA signaling will make autism worse. If GABA function has been shifted to inhibitory then amplifying GABA signaling will be calming.

Gene therapy will require much earlier diagnosis of single gene autisms.

“Precision medicine” therapies like Daybue/Trofinetide may not be that precise after all and large variations exist in the response, even among children with the same affected gene.

The huge expense means that for most of the world they will see no benefit from gene therapy or indeed “precision medicine.”

The low hanging fruit is to repurpose affordable existing drugs and get the benefit from their secondary effects.  This is what I term personalized medicine.

The research clearly indicates that some girls with Rett syndrome likely will benefit from Bumetanide therapy. For a young child this therapy would cost 50 US dollars/euros a year, if you pay the actual price for generics.

Why are they trialing genetic therapies for Rett instead of first doing the obvious thing and trialing cheap bumetanide? They will likely be able to sell the gene therapy for $2 million a shot.  There is little interest in trialing a $50 a year therapy.

Our new reader from Turkey, MÜCADELECI ANNE DENIZ ( = FIGHTING MOTHER DENIZ), likely does not have $2 million to spend, but seems to be on the way to creating her own personalized medicine therapy for her son. Good luck to her.

As to the cGP Max supplement, it seems to work for some and have no effect in others. Nobody has reported any side effects. It looks worth a try for Rett syndrome.  As a supplement it is not cheap, that is until you see what they charge for Daybue. 

Piperine/Resveratrol/Sunitinib for Rett’s and indeed much Autism? Or, R-Baclofen to raise KCC2 expression in Bumetanide-responsive autism.

Piperine/Pepper             Resveratrol/Red wine          Sunitinib/Sutent

  

This post is all about lowering chloride within neurons, by increasing the expression of the transporter that lets it leave, called KCC2.

Today’s post is one I never finished writing from last year; I looked up the price of Sutent/Sunitinib and then I remembered why. It does again highlight how cancer drugs, when they become cheap generics, will provide interesting options for autism treatment. It also shows again how Rett Syndrome is getting attention from researchers.

It also highlights that really clever Americans are looking for bumetanide alternatives, in the false belief that bumetanide has troubling side effects that cannot be managed/mitigated.

The study is by some clever guys in Cambridge Massachusetts.

Another group of clever guys from MIT burned through $40 million dollars a few years ago trying to develop R-Baclofen for Fragile-X and autism.  After that Roche-funded clinical trial failed, R-Baclofen has now been resurrected and a new trial is planned, with different end points (measures of success).

Today we see why many people should indeed respond positively to R-Baclofen, but the mode of action is entirely different to the one originally targeted by the clever guys from MIT.

Tucked away in the supplementary material of today’s paper we see that R-Baclofen increases the expression of the transporter (KCC2) that takes chloride out of neurons. So, R-Baclofen is doing the same thing as Bumetanide, just to a lesser extent and in a different way.  Both lower intracellular chloride.

That means that people responsive to bumetanide should get a further boost from R baclofen, but you might need a lot of it.

Clever they may be, but these researchers do not know how to communicate their findings.  I had to dig through the supplementary tables to extract the good stuff, which is a list of what substances increase KCC2 in regular brains (Table S1) and specifically in Rett Syndrome brains (Table S2).

This blog does rather bang on about blocking/inhibiting NKCC1 that lets chloride into neurons, you can of course alternatively open up KCC2 to let the chloride flood out. This latter strategy is proposed by the MIT researchers.

What really matters is the ratio KCC2/NKCC1.  In people with bumetanide-responsive autism, which pretty clearly will include girls with Rett Syndrome, you want to increase KCC2/NKCC1. So, block/down-regulate NKCC1 and/or up-regulate KCC2.

·        NKCC1↓

·        KCC2↑

The researchers identified 14 compounds.  To be useful as drugs these compounds have to be able to cross the blood brain barrier to be of much use, many do not.

In the paper they call KCC2 expression-enhancing compounds KEECs.

We have five approved drugs to add to the list that are functionally the same to primary hit compounds. 

·        Sunitinib

·        Crenolanib

·        Indirubin Monoxiome

·        Cabozantinib

·        TWS-119


The researchers went on to test just two compounds in Rett syndrome mice; they picked piperine (from black pepper) and KW 2449 (a leukemia drug)

Even R-baclofen pops up, with a “B score” of 6.65 (needs to be >3 to increase KCC2 expression).

Pharmacological enhancement of KCC2 gene expression exerts therapeutic effects on human Rett syndrome neurons and Mecp2 mutant mice.

Abstract

Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in the methyl CpG binding protein 2 (MECP2) gene. There are currently no approved treatments for RTT. The expression of K⁺/Cl^- cotransporter 2 (KCC2), a neuron-specific protein, has been found to be reduced in human RTT neurons and in RTT mouse models, suggesting that KCC2 might play a role in the pathophysiology of RTT. To develop neuron-based high-throughput screening (HTS) assays to identify chemical compounds that enhance the expression of the KCC2 gene, we report the generation of a robust high-throughput drug screening platform that allows for the rapid assessment of KCC2 gene expression in genome-edited human reporter neurons. From an unbiased screen of more than 900 small-molecule chemicals, we have identified a group of compounds that enhance KCC2 expression termed KCC2 expression-enhancing compounds (KEECs). The identified KEECs include U.S. Food and Drug Administration-approved drugs that are inhibitors of the fms-like tyrosine kinase 3 (FLT3) or glycogen synthase kinase 3β (GSK3β) pathways and activators of the sirtuin 1 (SIRT1) and transient receptor potential cation channel subfamily V member 1 (TRPV1) pathways. Treatment with hit compounds increased KCC2 expression in human wild-type (WT) and isogenic MECP2 mutant RTT neurons, and rescued electrophysiological and morphological abnormalities of RTT neurons. Injection of KEEC KW-2449 or piperine in Mecp2 mutant mice ameliorated disease-associated respiratory and locomotion phenotypes. The small-molecule compounds described in our study may have therapeutic effects not only in RTT but also in other neurological disorders involving dysregulation of KCC2.

Table S1. KEECs identified from screening with WT human KCC2 reporter neurons.

Table S2. KEECs identified from screening with RTT human KCC2 reporter neurons

Note Baclofen, Quercetin, Luteolin etc

Fig. 3. Identification of KEECs that increase KCC2 expression in human RTT neurons

B score >3 indicates compounds potentially increasing KCC2 expression

In cultured RTT neurons, treatment with KEECs KW-2449 and BIO restored the impaired KCC2 expression and rescued deficits in both GABAergic and glutamatergic neurotransmissions, as well as abnormal neuronal morphology. Previous data suggested that disrupted Cl− homeostasis in the brainstem causes abnormalities in breathing pattern (64), consistent with breathing abnormalities seen in mice carrying a conditional Mecp2 deletion in GABAergic neurons (67). The reduction in locomotion activity observed in the Mecp2 mutant mice has also been attributed to abnormalities in the GABAergic system (65). Therefore, treatment with the KEEC KW-2449 or piperine may ameliorate disease phenotypes in MeCP2 mutant mice through restoration of the impaired KCC2 expression and GABAergic inhibition.

Most KEECs that enhanced KCC2 expression in WT neurons, including KW-2449, BIO, and resveratrol, also induced a robust increase of KCC2 reporter activity in RTT neurons (Fig. 3, A and B; a complete list of hit compounds is provided in table S2). The increase in KCC2 signal induced by KEECs was higher in RTT neurons than in WT neurons,

1. 
   

Our results establish a causal relationship between reduced FLT3 or GSK3 signaling activity and increased KCC2 expression.

Two hit compounds, resveratrol and piperine, act on different pathways than the kinase inhibitors, activating the SIRT1 signaling pathway (50) and the TRPV1 (51), respectively

Thus, our data demonstrate that activation of the SIRT1 pathway or the TRPV1 channel enhances KCC2 expression in RTT human neurons.

The group of KEECs reported here may help to elucidate the molecular mechanisms that regulate KCC2 gene expression in neurons. A previous study conducted with a glioma cell line showed that resveratrol activates the SIRT1 pathway and reduces the expression of NRSF/REST (50), a transcription factor that suppresses KCC2 expression (52). Our results demonstrate that resveratrol increases KCC2 expression by a similar mechanism, which could contribute to the therapeutic benefit of resveratrol on a number of brain disease conditions (68, 69). We also identified a group of GSK3 pathway inhibitors as KEECs. Overactivation of the GSK3 pathway has been reported in a number of brain diseases (70). Thus, our results suggest that GSK3 pathway inhibitors could exert beneficial effects on brain function through stimulating KCC2 expression. Another major KEEC target pathway, the FLT3 kinase signaling, has been investigated as a cancer therapy target (71, 72). Although FLT3 is expressed in the brain (73), drugs that target FLT3 pathway have not been extensively studied as potential treatments for brain diseases. Our results provide the first evidence that FLT3 signaling in the brain is critical for the regulation of key neuronal genes such as KCC2. Therefore, this work lays the foundation for further research to repurpose a number of clinically approved FLT3 inhibitors as novel brain disease therapies

Our results are valuable for the development of novel therapeutic strategies to treat neurodevelopmental diseases through rectification of dysfunctional neuronal chloride homeostasis. Because of the lack of pharmaceutical reagents that enhance KCC2 expression, bumetanide, a blocker of the inward chloride transporter NKCC1 that counteracts KCC2, has been used as an alternative (74). Bumetanide treatment has shown benefits in treating symptoms in mouse models of fragile X syndrome (75) and Down’s syndrome (76) and was shown to confer symptomatic benefit to human patients with autism or fragile X syndrome (77, 78). These findings strongly suggest that pharmacological restoration of disrupted chloride homeostasis may provide symptomatic treatment for various neurodevelopmental and neuropsychiatric disorders. However, NKCC1 lacks the neuron- restricted expression pattern of KCC2 and is also expressed in nonbrain tissue including kidney and inner ears (79), consistent with knockout of Nkcc1 in mouse model leading to deafness and imbalance (30). Therefore, bumetanide treatment may trigger undesirable side effects, thus severely limiting its therapeutic application. In contrast, the expression of KCC2 is restricted to neurons, and a number of the KEECs identified in this study that enhance KCC2 expression in neurons are Food and Drug Administration–approved and have not elicited any severe adverse effects in clinical trials (80–83). The promising efficacy of KEECs demonstrated in this study and the known safety of the KCC2 target warrant further preclinical and clinical studies to investigate these drugs and their derivatives as potential therapies for neurodevelopmental diseases.

In summary, in this work, we investigated the efficacy of KEECs to rescue a number of well-documented cellular and behavior phenotypes of RTT, including impaired GABA functional switch, reductions in excitatory synapse number and strength, immature neuronal morphology (53, 54), as well as an increase in breathing pauses and a decrease in locomotion (84). It is possible, however, that KEECs may also be effective in treatment of conditions other than RTT, as impairment in KCC2 expression has been linked to many brain diseases (17, 85) including epilepsy (86–88), schizophrenia (19, 20, 89), brain and spinal cord injury (21, 90), stroke and ammonia toxicity conditions (91–93), as well as the impairments in learning and memory observed in the senile brain (23). Thus, a phenotypically diverse array of brain diseases may benefit from enhancing the expression of KCC2. The newly identified KEECs are potential therapeutic agents for otherwise elusive neurological disorders

Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in the methyl CpG binding protein 2 (MECP2) gene. There are currently no approved treatments for RTT. The expression of K+/Cl− cotransporter 2 (KCC2), a neuron-specific protein, has been found to be reduced in human RTT neurons and in RTT mouse models, suggesting that KCC2 might play a role in the pathophysiology of RTT. To develop neuron-based high-throughput screening (HTS) assays to identify chemical compounds that enhance the expression of the KCC2 gene, we report the generation of a robust high-throughput drug screening platform that allows for the rapid assessment of KCC2 gene expression in genome-edited human reporter neurons. From an unbiased screen of more than 900 small-molecule chemicals, we have identified a group of compounds that enhance KCC2 expression termed KCC2 expression– enhancing compounds (KEECs). The identified KEECs include U.S. Food and Drug Administration–approved drugs that are inhibitors of the fms-like tyrosine kinase 3 (FLT3) or glycogen synthase kinase 3 (GSK3) pathways and activators of the sirtuin 1 (SIRT1) and transient receptor potential cation channel subfamily V member 1 (TRPV1) pathways. Treatment with hit compounds increased KCC2 expression in human wild-type (WT) and isogenic MECP2 mutant RTT neurons, and rescued electrophysiological and morphological abnormalities of RTT neurons. Injection of KEEC KW-2449 or piperine in Mecp2 mutant mice ameliorated disease-associated respiratory and locomotion phenotypes. The small-molecule compounds described in our study may have therapeutic effects not only in RTT but also in other neurological disorders involving dysregulation of KCC2.

By screening these KCC2 reporter human neurons, we identified a number of hits KCC2 expression–enhancing compounds (KEECs) from ~900 small-molecule compounds. Identified KEECs were validated by Western blot and quantitative reverse transcription polymerase chain reaction (RT-PCR) experiments on cultured human wild-type (WT) and isogenic RTT neurons, as well as on organotypic mouse brain slices. Pharmacological and molecular biology experiments showed that identified KEECs act through inhibition of the fms-like tyrosine kinase 3 (FLT3) or glycogen synthase kinase 3b (GSK3b) kinases, or activation of the sirtuin 1 (SIRT1) or transient receptor potential cation channel subfamily V member 1 (TRPV1) pathways. Treatment of RTT neurons with KEECs rescued disease-related deficits in GABA functional switch, excitatory synapses, and neuronal morphological development. Last, injection of the identified KEEC KW-2449 or piperine into a Mecp2 mutant mice ameliorated behavioral phenotypes including breathing pauses and reduced locomotion, which represent important preclinical data, suggesting that the KEECs identified in this study may be effective in restoring impaired E/I balance in the RTT brain and provide symptomatic treatment for patients with RTT.

Fig. 2. KEEC treatment–induced enhancement of KCC2 protein and mRNA expression in cultured organotypic mouse brain slices and a hyperpolarizing EGABA shift in cultured immature neurons.

(E to G) KCC2 and NKCC1 mRNA expression induced by FLT3 inhibitors including sunitinib (n = 4), XL-184 (n = 6), crenolanib (n = 4), or a structural analog of BIO termed indirubin monoxime (n = 6). The calculated ratios of KCC2/NKCC1 mRNA expression are shown in (G). A.U., arbitrary units

Our results are valuable for the development of novel therapeutic strategies to treat neurodevelopmental diseases through rectification of dysfunctional neuronal chloride homeostasis. Because of the lack of pharmaceutical reagents that enhance KCC2 expression, bumetanide, a blocker of the inward chloride transporter NKCC1 that counteracts KCC2, has been used as an alternative (74). Bumetanide treatment has shown benefits in treating symptoms in mouse models of fragile X syndrome (75) and Down’s syndrome (76) and was shown to confer symptomatic benefit to human patients with autism or fragile X syndrome (77, 78). These findings strongly suggest that pharmacological restoration of disrupted chloride homeostasis may provide symptomatic treatment for various neurodevelopmental and neuropsychiatric disorders. However, NKCC1 lacks the neuron restricted expression pattern of KCC2 and is also expressed in nonbrain tissue including kidney and inner ears (79), consistent with knockout of Nkcc1 in mouse model leading to deafness and imbalance (30). Therefore, bumetanide treatment may trigger undesirable side effects, thus severely limiting its therapeutic application. In contrast, the expression of KCC2 is restricted to neurons, and a number of the KEECs identified in this study that enhance KCC2 expression in neurons are Food and Drug Administration–approved and have not elicited any severe adverse effects in clinical trials (80–83). The promising efficacy of KEECs demonstrated in this study and the known safety of the KCC2 target warrant further preclinical and clinical studies to investigate these drugs and their derivatives as potential therapies for neurodevelopmental diseases.

In summary, in this work, we investigated the efficacy of KEECs to rescue a number of well-documented cellular and behavior phenotypes of RTT, including impaired GABA functional switch, reductions in excitatory synapse number and strength, immature neuronal morphology (53, 54), as well as an increase in breathing pauses and a decrease in locomotion (84). It is possible, however, that KEECs may also be effective in treatment of conditions other than RTT, as impairment in KCC2 expression has been linked to many brain diseases (17, 85) including epilepsy (86–88), schizophrenia (19, 20, 89), brain and spinal cord injury (21, 90), stroke and ammonia toxicity conditions (91–93), as well as the impairments in learning and memory observed in the senile brain (23). Thus, a phenotypically diverse array of brain diseases may benefit from enhancing the expression of KCC2. The newly identified KEECs are potential therapeutic agents for otherwise elusive neurological disorders.

The science-light version:-

Drug screen reveals potential treatments for Rett syndrome

An experimental leukemia drug and a chemical in black pepper ease breathing and movement problems in a mouse model of Rett syndrome, according to a new study.

Rett syndrome is a rare brain condition related to autism, caused by mutations in the MECP2 gene. Because the gene is located on the X chromosome, the syndrome occurs almost exclusively in girls. No drugs are available to treat Rett.

The team screened 929 compounds from three large drug libraries, including one focused on Rett therapies. They found 30 compounds that boost KCC2’s expression in the MECP2 neurons; 14 of these also increased the protein’s expression in control neurons.

The team tested two of the identified compounds in mice with mutations in MECP2: KW-2449, which is a small molecule in clinical trials for leukemia, and piperine, an herbal supplement and component of black pepper. These mice have several traits reminiscent of Rett. They are prone to seizures, breathing problems, movement difficulties and disrupted social behavior.

Injecting the mice with either drug daily for two weeks improved the animals’ mobility relative to untreated mice. The drugs also eased the mice’s breathing problems, decreasing the frequency of pauses in breathing (apnea). The findings appeared in July in Science Translational Medicine.

 

Piperine, Resveratrol and analogs thereof

Piperine and Resveratrol are commercially available supplements.

Resveratrol has been mentioned many times in this blog.  It has numerous beneficial properties, to which we can now add increasing KCC2 expression, but it is held back by its poor ability to cross the blood barrier.

The other natural substance highlighted in the study is piperine. Piperine is the substance that gets added to curcumin to increases its bioavailability and hopefully get its health benefits.

Piperine has been recently been found to be a positive allosteric modulator of GABA_A receptors.

It may be that piperine has 2 different effects on GABA, or maybe it is just the same one?

The result is that people are trying to develop modified versions of piperine that could be patentable commercial drugs.

Piperine also activated TRPV1 receptors.

You might wonder what is the effect in humans of plain old piperine in bumetanide-responsive autism.

Invitro blood–brain-barrier permeability predictions for GABAA receptor modulating piperine analogs

The alkaloid piperine from black pepper (Piper nigrum L.) and several synthetic piperine analogs were recently identified as positive allosteric modulators of γ-aminobutyric acid type A (GABA_A) receptors. In order to reach their target sites of action, these compounds need to enter the brain by crossing the blood–brain barrier (BBB). We here evaluated piperine and five selected analogs (SCT-66, SCT-64, SCT-29, LAU397, and LAU399) regarding their BBB permeability. Data were obtained in three in vitro BBB models, namely a recently established human model with immortalized hBMEC cells, a human brain-like endothelial cells (BLEC) model, and a primary animal (bovine endothelial/rat astrocytes co-culture) model. For each compound, quantitative UHPLC-MS/MS methods in the range of 5.00–500 ng/mL in the corresponding matrix were developed, and permeability coefficients in the three BBB models were determined. In vitro predictions from the two human BBB models were in good agreement, while permeability data from the animal model differed to some extent, possibly due to protein binding of the screened compounds. In all three BBB models, piperine and SCT-64 displayed the highest BBB permeation potential. This was corroborated by data from in silico prediction. For the other piperine analogs (SCT-66, SCT-29, LAU397, and LAU399), BBB permeability was low to moderate in the two human BBB models, and moderate to high in the animal BBB model. Efflux ratios (ER) calculated from bidirectional permeability experiments indicated that the compounds were likely not substrates of active efflux transporters.

The alkaloid piperine, the major pungent component of black pepper (Piper nigrum L.), was recently identified as a positive allosteric γ-aminobutyric acid type A (GABAA) receptor modulator. The compound showed anxiolytic-like activity in behavioral mouse models, and was found to interact with the GABAA receptors at a binding site that was independent of the benzodiazepine binding site [1,2]. Given that the compound complied with Lipinski’s “rule of five” [1], it represented a new scaffold for the development of novel GABAA receptor modulators [1–3]. Given that piperine also activates the transient receptor potential vanilloid 1 (TRPV1) receptors [4] which are involved in pain signaling and regulation of the body temperature [5,6], structural modification of the parent compound was required to dissect GABAA and TRPV1 activating properties

For drugs acting on the central nervous system (CNS), brain penetration is required. This process is controlled by the blood-brain barrier (BBB), a tight layer of endothelial cells lining the brain capillaries that limits the passage of molecules from the blood circulation into the brain [10]. Since low BBB permeability can reduce CNS exposure [11], lead compounds should be evaluated at an early stage of the drug development process for their ability to permeate the BBB [12].

Conclusions

Piperine and five selected piperine analogs with positive GABAA receptor modulatory activity were screened in three in vitro cell-based human and animal BBB models for their ability to cross the BBB. Data from the three models differed to some extent, possibly due to protein binding of the piperine analogs. In all three models, piperine and SCT-64 displayed the highest BBB permeation potential, which could be corroborated by in silico prediction data. For the other piperine analogs (SCT-66, SCT-29, LAU397, and LAU399), BBB permeability was low to moderate in the two human models, and moderate to high in the animal model. ER calculated from bidirectional permeability experiments indicated that the compounds were likely not substrates of active efflux. In addition to the early in vitro BBB permeability assessment of the compounds, further studies (such as PK and drug metabolism studies) are currently in progress in our laboratory. Taken together, these data will serve for selecting the most promising candidate molecule for the next cycle of medicinal chemistry optimization

Conclusion

My conclusions are a little different to the MIT researchers

“The newly identified KEECs are potential therapeutic agents for otherwise elusive neurological disorders.”

This assumes that you cannot safely use bumetanide/azosemide, which you can.  Open your eyes and look at France, where several hundred children with autism are safely taking bumetanide.

”It is possible, however, that KEECs may also be effective in treatment of conditions other than RTT, as impairment in KCC2 expression has been linked to many brain diseases”

We have copious evidence that elevated chloride is a feature of many conditions, not just Rett’s and an effective cheap therapy has been sitting in the pharmacy for decades.

In the clinical trial of R-Baclofen that failed, there were some positive effects on some subjects.  Were the positive effects just caused by the effect of Baclofen in increasing KCC2 expression?

Should R-Baclofen become a cheap generic, it might indeed become a useful add-on for those with bumetanide-responsive. Regular Baclofen (Lioresal) is an approved drug, but it does have some side effects, so most likely R-baclofen will have side effects in some.

Baclofen itself in modest doses has little effect on bumetanide-responsive autism.

A cheap side-effect free KCC2 enhancer would be a good drug for autism, although cheap, safe NKCC1 blockers already exist. 

I have no idea if piperine benefits bumetanide-responsive autism.  Piperine has long been used in traditional medicine.

The TRPV1 receptor also affected by piperine plays a role in pain and anxiety.

We saw in the post below that TRPV1 controls cortical microglia activation and that GABARAP modulates TRPV1 expression.

So, TRPV1 and GABA_A receptors are deeply intertwined.

  

GABAa receptor trafficking, Migraine, Pain, Light Sensitivity, Autophagy, Jacobsen Syndrome,Angelman Syndrome, GABARAP, TRPV1, PX-RICS, CaMKII and CGRP ... Oh and the"fever effect"

Is Piperine going to make autism better, or worse?