The Kynurenine Pathway in Autism and its modification using Sulforaphane or the probiotic Lactobacillus Plantarum 299v

 

 A pathway to somewhere, hopefully

Today’s post was prompted by our reader George’s observation that the probiotic Lactobacillus Plantarum 299v increased speech in his adult son.  This widely available probiotic is commonly used to treat IBS (Irritable Bowel Syndrome) and I did mention it in a recent post about Eubiotics.

Eubiotics for GI Dysfunction and some Autism

Increased speech is a target for many people treating autism and this probiotic is known to be safely used long term - so it is interesting.

Since I already had this probiotic at home, I made a trial and I observed a very similar effect to what happened several years ago when Monty started to use Sulforaphane / broccoli sprout powder. 

The effect of broccoli powder was a brief period of euphoria about 20 minutes later and a then a marked increase in verbalization.  The effect on mood was seen by some other readers, but not the majority. I recall back then a very happy parent who was feeding broccoli powder to his child via a G-tube. A gastrostomy tube, often called a G-tube, is a surgically placed device used to give direct access to your child's stomach for supplemental feeding, hydration or medication.  Some children with autism will not eat and so are fed via a G-tube.

Broccoli powder tastes pretty bad, but this is one problem you will not experience when taking it via a G tube.

I was surprised that even some people with mild autism found broccoli powder beneficial. In diabetics it improves insulin sensitivity and so reduces the amount of insulin they need to inject.

This post is about the science, but before reading all the science, I made my trial of Lactobacillus Plantarum 299v.  One capsule a day works very nicely. The science is optional.

I wondered what might be the shared effect of these two very different therapies - broccoli and L.P. 299v.  There is indeed a plausible explanation, the Kynurenine pathway.

 

Click on the graphic, to enlarge

This may all look rather complicated, but there are some terms we are already very familiar with. We know that Serotonin is the happy hormone and we know that Melatonin is the sleep hormone.

It all starts with Tryptophan, one of those amino acids. It is essential in humans, meaning that the body cannot synthesize it and it must be obtained from the diet. Good sources include milk, turkey and bananas. If you take bumetanide, you likely already eat a lot of bananas due to their potassium content.

95% of tryptophan is metabolized to Kynurenine, a very odd sounding word. So it must be that less than 5% becomes Serotonin and Melatonin. Two enzymes, namely indoleamine 2,3-dioxygenase (IDO) in the immune system and the brain, and tryptophan dioxygenase (TDO) in the liver, are responsible for the synthesis of kynurenine from tryptophan.

The so-called kynurenine pathway of tryptophan is altered in several diseases, including psychiatric disorders such as autism, schizophrenia, major depressive disorder and bipolar disorder.

The supplements Tryptophan and 5-hydroxytryptophan (5-HTP) are widely used for many conditions ranging from depression to autism.

 

The kynurenine pathway is a metabolic pathway leading to the production of nicotinamide adenine dinucleotide (NAD⁺).

 

NAD⁺ is very important.

 

Increasing the level of NAD is itself an autism therapy in the research. 

New Preclinical Study Finds Niagen® Corrects Social Deficits in Mouse Model of Autism

First-of-its-kind preclinical study shows that Niagen® (nicotinamide riboside) resolves social deficits and anxiety-like behaviors in male mice

The amount of Tryptophan that ends up as the cute-sounding Picolinic acid is determined by how much of the enzyme ACMSD is present.

Quinolinic acid (QUIN) and Kynurenic acid (KYNA) are two neuroactive KP metabolites that have received considerable attention for their modulation of the NMDA receptor. While QUIN shows neurotoxic effects by over activation of the NMDA receptor, KYNA offers neuro-protection by blocking receptor function. Emphasis has been placed upon the importance of maintaining a balanced ratio between these two metabolites.

Picolinic acid (PIC) also shows antagonistic properties towards the toxic effects of QUIN via an unknown mechanism.  There are a number of biological factors that can potentially affect PIC levels and synthesis in the CNS including age, circadian rhythms and hormonal and nutritional factors.

 

 Source: The Physiological Action of Picolinic Acid in the Human Brain

Anthranilic acid (AA), once thought to be vitamin L, is very elevated in schizophrenia, and also in type-1 diabetes and arthritis.  AA is seen as a treatment target in these conditions. 

Now for the interesting part, the effect of the probiotic Lactobacillus Plantarum 299v on the Kynurenine pathway:

 

Probiotic Lactobacillus Plantarum 299v decreases kynurenine concentration and improves cognitive functions in patients with major depression: A double-blind, randomized, placebo controlled study

Highlights

· There was an improvement in cognitive functions in group of depressed patients receiving probiotic Lactobacillus Plantarum 299v (LP299v) compared to the placebo group.

 · There was a significant decrease in kynurenine concentration in the LP299v group compared to the placebo group.

 · There was a significant increase in 3-hydroxykynurenine : kynurenine ratio in the LP299v group compared with the placebo group.

· Decreased kynurenine concentration due to probiotic could contribute to the improvement of cognitive functions in the LP299v group compared to the placebo group.

  

And, the effect of Sulforaphane on the Kynurenine pathway: 

 

Altered kynurenine pathway metabolism in autism:Implication for immune-induced glutamatergic activity

Dysfunction of the serotoninergic and glutamatergic systems is implicated in the pathogenesis of autism spectrum disorder (ASD) together with various neuroinflammatory mediators. As the kynurenine pathway (KP) of tryptophan degradation is activated in neuroinflammatory states, we hypothesized that there may be a link between inflammation in ASD and enhanced KP activation resulting in reduced serotonin synthesis from tryptophan and production of KP metabolites capable of modulating glutamatergic activity. A cross-sectional study of 15 different Omani families with newly diagnosed children with ASD (n = 15) and their age-matched healthy siblings (n = 12) was designed. Immunological profile and the KP metabolic signature were characterized in the study participants. Our data indicated that there were alterations to the KP in ASD. Specifically, increased production of the downstream metabolite, Quinolinic acid, which is capable of enhancing glutamatergic neurotransmission was noted. Correlation studies also demonstrated that the presence of inflammation induced KP activation in ASD. Until now, previous studies have failed to establish a link between inflammation, glutamatergic activity, and the KP. Our findings also suggest that increased Quinolinic acid may be linked to 16p11.2 mutations leading to abnormal glutamatergic activity associated with ASD pathogenesis and may help rationalize the efficacy of sulforaphane treatment in ASD.

 

QA = Quinolinic Acid

KP = Kynurenine Pathway

 

The increased concentration of QA in ASD is also likely to be associated with increased oxidative stress. We previously showed that QA can significantly potentiate oxidative stress in human primary neuron cultures and that oxidative stress markers are increased in children with ASD.  Recently, a clinical study effectively used sulforaphane derived from the broccoli sprout to treat ASD resulting in improved behaviour.  Interestingly, sulforaphane was shown to attenuate the effect of QA-induced toxicity in rat brain by enhancing the antioxidant, glutathione. This study is coherent with our current finding of increased QA in children with ASD and our previous work showing decreased glutathione in the children with ASD.  Hence, the possibility that sulforaphane may act by attenuating QA-induce oxidative stress in ASD warrants further investigation.

 

Conclusion

Too much Quinolinic Acid (QA) does appear to be a damaging feature of autism and is produced by a malfunctioning Kynurenine pathway (KP).

The exact relevance of each part of the KP in diseases of the brain is still a work in progress, but it is clearly disturbed in a specific way in each particular CNS disorder, autism being just one.

Modifying the KP does look like a useful therapeutic avenue to follow, but it is not so simple to understand all of it.

It appears that Lactobacillus Plantarum 299v may improve some people’s autism via a mechanism that includes modification of the Kynurenine pathway (KP). It may also be the case that sulforaphane / broccoli powder has an effect that counters the disturbed KP. For whatever biological reason, the visible/audible effects of the two therapies appear to be remarkably similar.

As usual, you do not have to fully understand biological pathways, like the KP, to benefit from them.  In effect, it is all a question of where all the Tryptophan from your diet ends up – and for some people it does seem to matter.

Lactobacillus Plantarum 299v and sulforaphane / broccoli are not wonder autism therapies for most responders, but if there is an incremental benefit available, you may want to take it.

Another low hanging fruit? 

 

How to increase Oxytocin (OT) effects in the autistic brain? OT nasal spray, L. reuteri DSM 17938, Magnesium, Estradiol, Nicotinamide riboside …

 Struggle to make friends? Consider Oxytocin

Today’s post was going to be about FMT super-donors, but instead we have a post about new insights into using oxytocin to treat autism.  From personal experience I can say that you really can target oxytocin receptors to affect mood/behavior; I have no personal experience of FMT (fecal microbiota transplants), but thousands of people use it for many conditions.  The FMT post will be next.

Oxytocin and vasopressin are two hormones, made in the hypothalamus, that are established targets for autism treatment. They are released into the bloodstream where they carry out their best-known functions, but they are also released from the hypothalamus directly into the brain where these hormones have entirely different functions.

Both oxytocin and vasopressin can be given as nasal sprays to enter the central nervous system (CNS) rather than just the blood stream.  This means you get the brain effects of the hormone, also known as the “central effects”.

As was discussed previously in this blog and is highlighted more recently in the article below, you can use certain bacteria in the gut to signal to the hypothalamus to produce more oxytocin.  This is really clever and it works in humans, not just research animals.  It also has the advantage of producing a more continuous effect than is found using the intranasal method to deliver oxytocin. 

When you sever the vagus nerve, the bacteria in the gut continues to produce the required chemicals, but the signal to the brain has been lost. The hypothalamus no longer produces increased oxytocin and so the behavioral/mood effect is lost. This has been proven in the research.

Gut microbes may treat social difficulties in autism mice

In science speak, “the results suggest that a peptide or metabolite produced by bacteria may modulate host oxytocin secretion for potential public or personalized health goals”.  It also appears that oxytocin improves wound healing. So perhaps old people with leg ulcers, which never seem to get better, might benefit from a daily dose of L. reuteri DSM 17938, it also might make them feel better due to those central effects.

Oxytocin in the brain acts via oxytocin receptors

As we learned years ago in this blog, you can increase the effect (turn up the volume) of receptors using a PAM (positive allosteric modulator).  Interestingly, magnesium is a PAM of the oxytocin receptor (OTR).  Many people with autism are supplementing magnesium, perhaps those using intranasal oxytocin should join them. 

A very recent paper has investigated in detail how oxytocin receptors function.

Crystal structure of the human oxytocin receptor

The peptide hormone oxytocin modulates socioemotional behavior and sexual reproduction via the centrally expressed oxytocin receptor (OTR) across several species. Here, we report the crystal structure of human OTR in complex with retosiban, a nonpeptidic antagonist developed as an oral drug for the prevention of preterm labor. Our structure reveals insights into the detailed interactions between the G protein–coupled receptor (GPCR) and an OTR-selective antagonist. The observation of an extrahelical cholesterol molecule, binding in an unexpected location between helices IV and V, provides a structural rationale for its allosteric effect and critical influence on OTR function. Furthermore, our structure in combination with experimental data allows the identification of a conserved neurohypophyseal receptor-specific coordination site for Mg2+ that acts as potent, positive allosteric modulator for agonist binding. Together, these results further our molecular understanding of the oxytocin/vasopressin receptor family and will facilitate structure-guided development of new therapeutics. 

Magnesium and mood disorders: systematic review and meta-analysis

Another consequence of ERβ under-expression in autism

Also interesting to those following autism research, is the role of ERβ (estrogen receptor beta).  It is well known that in the brains of those with autism, there is a lack of ERβ.  A lack of ERβ is likely to lead to lower oxytocin in the brain and CSF (spinal fluid).  In many types of autism, we know that the level of oxytocin in CSF is reduced.

If you activate ERβ you both increase expression of oxytocin receptor (OTR) and also increase the level of oxytocin measured in the CSF.  You can activate ERβ with estrogens, like estradiol or even phytoestrogens like soy.  The ideal therapy to use would be DHED.

https://epiphanyasd.blogspot.com/2018/02/dhed-delivering-estradiol-only-to-brain.html

The cheap diuretic spironolactone may very well indirectly increase the level of oxytocin in CSF.

Oxytocin and Estrogen Receptor β in the Brain: An Overview

Oxytocin (OT) is a neuropeptide synthesized primarily by neurons of the paraventricular and supraoptic nuclei of the hypothalamus. These neurons have axons that project into the posterior pituitary and release OT into the bloodstream to promote labor and lactation; however, OT neurons also project to other brain areas where it plays a role in numerous brain functions. OT binds to the widely expressed OT receptor (OTR), and, in doing so, it regulates homeostatic processes, social recognition, and fear conditioning. In addition to these functions, OT decreases neuroendocrine stress signaling and anxiety-related and depression-like behaviors. Steroid hormones differentially modulate stress responses and alter OTR expression. In particular, estrogen receptor β activation has been found to both reduce anxiety-related behaviors and increase OT peptide transcription, suggesting a role for OT in this estrogen receptor β-mediated anxiolytic effect. Further research is needed to identify modulators of OT signaling and the pathways utilized and to elucidate molecular mechanisms controlling OT expression to allow better therapeutic manipulations of this system in patient populations.

NAD and Nicotinamide Riboside to boost Oxytocin

Today we see that recent research from Japan shows that in those people with autism who have reduced NAD, they may well be able to improve behavior/mood by increasing the level of their oxytocin using Nicotinamide Riboside (NR).

Nicotinamide riboside (NR) is a special form of vitamin B3, sold as an expensive supplement.  The FDA say it is safe for use in humans.

Nicotinamide riboside supplementation corrects deficits in oxytocin, sociability and anxiety of CD157 mutants in a mouse model of autism spectrum disorder

Oxytocin (OT) is a critical molecule for social recognition and memory that mediates social and emotional behaviours. In addition, OT acts as an anxiolytic factor and is released during stress. Based on the activity of CD38 as an enzyme that produces the calcium-mobilizing second messenger cyclic ADP-ribose (cADPR), CD157, a sister protein of CD38, has been considered a candidate mediator for the production and release of OT and its social engagement and anti-anxiety functions. However, the limited expression of CD157 in the adult mouse brain undermined confidence that CD157 is an authentic and/or actionable molecular participant in OT-dependent social behaviour. Here, we show that CD157 knockout mice have low levels of circulating OT in cerebrospinal fluid, which can be corrected by the oral administration of nicotinamide riboside, a recently discovered vitamin precursor of nicotinamide adenine dinucleotide (NAD). NAD is the substrate for the CD157- and CD38-dependent production of cADPR. Nicotinamide riboside corrects social deficits and fearful and anxiety-like behaviours in CD157 knockout males. These results suggest that elevating NAD levels with nicotinamide riboside may allow animals with cADPR- and OT-forming deficits to overcome these deficits and function more normally.

NR elevates brain NAD⁺ and cerebrospinal OT

Social preference deficit and anxiety of CD157KO males are best corrected at a relatively low dose of NR

The results demonstrated that the daily oral administration of NR rescued the social behavioural impairments observed in male CD157KO mice. NR had essentially no effects on social behaviour in wild-type male mice. The beneficial effects of NR appear to depend on restoration of CSF OT levels because the NR-induced OT elevation was only detected in CD157KO mice, which have a CSF OT deficit.

In the course of identifying a nutritional intervention for CD157KO mice, we reproduced the anxiety-like and social-avoidance-like deficits reported previously. Reproducibly lower levels of CSF OT in male CD157KO mice make these mice an attractive model of autism, anxiety disorder, or social avoidance in neurodegenerative diseases. Significantly, this model responds to both OT and NR as a treatment.

The challenge of polygenic diseases of incomplete penetrance is that they are difficult to understand mechanistically. Multiple genetic and environmental (biochemical) factors may converge to dysregulate pathways that are altered in common conditions such as ASD. We note that one potentially hopeful point when studying polygenetic diseases is that brain systems are redundant, and thus, it may be possible to increase normal functions that are only partially encoded by genetically damaged circuitry.

NAD⁺ is consumed by CD38 in formation of cyclic ADP-ribose. It then participates in OT release in the hypothalamus. In our study, ADP-ribosyl cyclase activity was maintained at a similar range as that in wild-type animals (data not shown). A recent study suggested that NR supplementation did not change CD38 expression. However, in vitro studies have shown that NAD⁺ applied to the mouse hypothalamus leads to OT release. It is reasonable to assume that an elevation in NAD⁺ levels by NR in the hypothalamus is responsible for repair of the OT release.

Future work will probe CD38 dependence and the cell-type dependence of the beneficial effects of NR on CD157KO behaviour, the potential benefits of NR in other ASD models, and the potential of NR to become a safe nutritional intervention, in addition to OT, for at least some types of ASD in human populations.

NAD+ is reduced in older people

There is a lot of research into combating the effects of aging.  It is agreed that the older you get, the less NAD+ you have and so research has looked at numerous ways to raise it.

The CD157KO mice model of autism does feature reduced NAD+, but nobody knows how common reduced NAD+ is in autism.

If you have low levels of NAD+ there will be negative consequences.

I think you can consider NAD+ depletion in a similar way to oxidative stress, both are inevitable and damaging features of aging.

Most healthy younger people are likely wasting their time and money worrying about oxidative stress and NAD+.  These are the people with “detox” diets and juices.

However, most old people and some young people with autism really stand to benefit from correcting oxidative stress and any reduced NAD+.

  

Therapeutic potential of NAD-boosting molecules: the in vivo evidence

Hallmarks of NAD homeostasis

NAD⁺ is not merely a redox co-factor, it is also a key signaling molecule that controls cell function and survival in response to environmental changes such as nutrient intake and cellular damage. Fluctuations in NAD impact mitochondrial function and metabolism, redox reactions, circadian rhythm, immune response and inflammation, DNA repair, cell division, protein-protein signaling, chromatin and epigenetics.

There are many ways to boost NAD+.

Classes of NAD+ boosting molecules and known effects in humans

NAD+ Precursors              

Niacin/ nicotinic acid (NA), Nicotinamide riboside (NR) Nicotinamide (NAM) etc.

CD38 Inhibitors                 

Flavonoids (Quercetin, Luteolin, Apigenin, fisetin, rutin and naringin)             

Luteolinidin.  Kuromanin/ Chrysanthemin, an anthocyanin (food pigment)    

PARP Inhibitors    

BGB-290, Olaparib, Rucaparib, Veliparib, CEP-9722, E7016, Talazoparib, Iniparib, Niraparib, PJ34, DPQ, 3-aminobenzamide

                       

SARM Inhibitors

XAV939                    

NAMPT Activators

P7C3 

Conclusion

Some readers of this blog do give intranasal oxytocin as a therapy.  There have been numerous studies on children with autism, some discussed in earlier posts.  Oxytocin needs to be kept chilled, not to lose its potency.

Eleven previous posts in this blog refer to Oxytocin.

https://epiphanyasd.blogspot.com/search/label/Oxytocin

As to whether stimulating oxytocin receptors is going to be worthwhile in your case of autism, you will just have to try it and see.

I found that the Biogaia Protectis probiotic (L. reuteri DSM 17938) had very clear effects, which were very much hallmark effects of oxytocin.  This is easy and inexpensive to try.

Some readers of this blog do use Nicotinamide Riboside (NR), which we saw today can increase oxytocin by increasing NAD+.

There are very many reasons why you do not want to be lacking in NAD+, other than oxytocin, but if you already have plenty NAD+ you will unlikely see a benefit from yet more.

Magnesium is a very common autism supplement; it is often given with vitamin B6; both can be used to treat stress.

Superiority of magnesium and vitamin B6 over magnesium alone on severe stress in healthy adults with low magnesemia: A randomized, single-blind clinical trial