Tag: tryptophan catabolites

In Schizophrenia, Chronic Fatigue Syndrome- and Fibromyalgia-Like Symptoms are Driven by Breakdown of the Paracellular Pathway with Increased Zonulin and Immune Activation-Associated Neurotoxicity

Abstract:

Background: A meaningful part of schizophrenia patients suffer from physiosomatic symptoms (formerly named psychosomatic) which are reminiscent of chronic fatigue syndrome and fibromyalgia (FF) and are associated with signs of immune activation and increased levels of tryptophan catabolites (TRYCATs).

Aims: To examine whether FF symptoms in schizophrenia are associated with breakdown of the paracellular pathway, zonulin, lowered natural IgM responses to oxidative specific epitopes (OSEs); and whether FF symptoms belong to the behavioral-cognitive-physical-psychosocial-(BCPS)-worsening index consisting of indices of a general cognitive decline (G-CoDe), symptomatome of schizophrenia, and quality of life (QoL)-phenomenome.

Methods: FF symptoms were assessed using the Fibromyalgia and Chronic Fatigue Rating scale in 80 schizophrenia patients and 40 healthy controls and serum cytokines/chemokines, IgA levels to TRYCATs, IgM to OSEs, zonulin and transcellular/paracellular (TRANS/PARA) molecules were assayed using ELISA methods.

Results: A large part (42.3%) of the variance in the total FF score was explained by the regression on the PARA/TRANS ratio, pro-inflammatory cytokines, IgM to zonulin, IgA to TRYCATs (all positively) and IgM to OSEs (inversely). There were highly significant correlations between the total FF score and G-CoDe, symtopmatome, QoL phenomenome and BCPS-worsening score. FF symptoms belong to a common core shared by G-CoDe, symtopmatome, and QoL phenomenome.

Discussion: The physio-somatic symptoms of schizophrenia are driven by various pathways including increased zonulin, breakdown of the paracellular tight-junctions pathway, immune activation with induction of the TRYCAT pathway, and consequent neurotoxicity. It is concluded that FF symptoms are part of the phenome of schizophrenia and BCPS-worsening as well.

Source: Maes M, Andrés-Rodríguez L, Vojdani A, Sirivichayakul S, Barbosa DS, Kanchanatawan B. In Schizophrenia, Chronic Fatigue Syndrome- and Fibromyalgia-Like Symptoms are Driven by Breakdown of the Paracellular Pathway with Increased Zonulin and Immune Activation-Associated Neurotoxicity. CNS Neurol Disord Drug Targets. 2022 Aug 6. doi: 10.2174/1871527321666220806100600. Epub ahead of print. PMID: 35946099.

Markers of fungal translocation are elevated during post-acute sequelae of SARS-CoV-2 and induce NF-κB signaling

Abstract:

Long COVID, a type of Post-Acute Sequelae of SARS-CoV-2 (PASC), has been associated with sustained elevated levels of immune activation and inflammation. However, the mechanisms that drive this inflammation remain unknown. Inflammation during acute Coronavirus Disease 2019 could be exacerbated by microbial translocation (from gut and/or lung) to blood. Whether microbial translocation contributes to inflammation during PASC is unknown.

We did not observe a significant elevation in plasma markers of bacterial translocation during PASC. However, we observed higher levels of fungal translocation – measured as β-glucan, a fungal cell wall polysaccharide – in the plasma of individuals experiencing PASC compared to those without PASC or SARS-CoV-2 negative controls. The higher β-glucan correlated with higher inflammation and elevated levels of host metabolites involved in activating N-Methyl-D-aspartate receptors (such as metabolites within the tryptophan catabolism pathway) with established neuro-toxic properties. Mechanistically, β-glucan can directly induce inflammation by binding to myeloid cells (via Dectin-1) and activating Syk/NF-κB signaling.

Using a Dectin-1/NF-κB reporter model, we found that plasma from individuals experiencing PASC induced higher NF-κB signaling compared to plasma from negative controls. This higher NF-κB signaling was abrogated by Piceatannol (Syk inhibitor). These data suggest a potential targetable mechanism linking fungal translocation and inflammation during PASC.

Source: Giron LB, Peluso MJ, Ding J, Kenny G, Zilberstein NF, Koshy J, Hong KY, Rasmussen H, Miller GE, Bishehsari F, Balk RA, Moy JN, Hoh R, Lu S, Goldman AR, Tang HY, Yee BC, Chenna A, Winslow JW, Petropoulos CJ, Kelly JD, Wasse H, Martin JN, Liu Q, Keshavarzian A, Landay A, Deeks SG, Henrich TJ, Abdel-Mohsen M. Markers of fungal translocation are elevated during post-acute sequelae of SARS-CoV-2 and induce NF-κB signaling. JCI Insight. 2022 Jun 21:e160989. doi: 10.1172/jci.insight.160989. Epub ahead of print. PMID: 35727635. https://pubmed.ncbi.nlm.nih.gov/35727635/

The Many Neuroprogressive Actions of Tryptophan Catabolites (TRYCATs) that may be Associated with the Pathophysiology of Neuro-Immune Disorders

Abstract:

Many, if not all, chronic medical, neurodegenerative and neuroprogressive illnesses are characterised by chronic immune activation, oxidative and nitrosative stress (O&NS) and systemic inflammation. These factors, notably elevated pro-inflammatory cytokines, activate indoleamine 2,3-dioxygenase (IDO) leading to an upregulated tryptophan catabolite (TRYCAT) pathway of tryptophan degradation in the periphery and in the brain. In such conditions the TRYCAT pathway becomes the predominant system for tryptophan degradation in all body compartments.

In this paper we review the pathways whereby TRYCATs may play a role in neuro-inflammatory and neuroprogressive disease. Thus chronic activation of the TRYCAT pathway leads to the production of a range of neuroactive, neuroprotective and neurotoxic TRYCATs. Some TRYCATs such as quinolinic acid act as potent neurotoxins which inhibit ATP production by mitochondria, provoke increases in O&NS, disrupt neuron glial communication and blood brain barrier integrity, induce apoptosis of glial cells, directly damage neurons and function as a N-methyl D-aspartate (NMDA) receptor agonist.

Other TRYCATs such as kynurenic acid function as antagonists of NMDA, α- amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and kainate receptors and act to regulate levels of glutamate and dopamine.

The neuroprotective functions of this TRYCAT are likely exercised via engagement with alpha7 nicotinic acetylcholine and aryl hydrocarbon receptors but the neuroprotective effects stemming from elevated kynurenic acid levels come at the price of severely compromised neurocognitive function and emotional processing. Other TRYCATS also possess neurotoxic or neuroprotective properties via pro-oxidant and antioxidant effects.

Here we discuss the involvement of the above mentioned TRYCAT pathways in schizophrenia, Alzheimer’s disease and chronic fatigue syndrome.

Source: Morris G, Carvalho AF, Anderson G, Galecki P, Maes M. The Many Neuroprogressive Actions of Tryptophan Catabolites (TRYCATs) that may be Associated with the Pathophysiology of Neuro-Immune Disorders. Curr Pharm Des. 2016;22(8):963-77. https://www.ncbi.nlm.nih.gov/pubmed/26667000