Homotaurine limits the spreading of T cell autoreactivity within the CNS and ameliorates disease in a model of multiple sclerosis

A novel combination approach to effectively reduce inflammation and neurodegeneration in multiple sclerosis models

Multiple sclerosis (MS) is an autoimmune disease characterized by immune-mediated attacks on the central nervous system (CNS), resulting in demyelination and recurring T-cell responses. Unfortunately, there is no cure for it. Current therapies that target immunomodulation and/or immunosuppression show only modest beneficial effects, have many side effects, and do not block neurodegeneration or progression of the disease. Since neurodegeneration and in particular axonal degeneration is implicated in disability in progressive MS, development of novel therapeutic strategies to attenuate the neurodegenerative processes is imperative. This study aims to develop new safe and efficacious treatments that address both the inflammatory and neurodegenerative aspects of MS using its animal model, experimental allergic encephalomyelitis (EAE). In EAE, the cysteine protease calpain is upregulated in CNS tissue, and its activity correlates with neurodegeneration. Our immunologic studies on MS have indicated that increased calpain activity promotes pro-inflammatory T helper (Th)1 cells and the severity of the disease in EAE, suggesting that calpain inhibition could be a novel target to combat neurodegeneration in MS/EAE. While calpain inhibition by SNJ1945 reduced disease severity, treatment of EAE animals with a novel protease-resistant altered small peptide ligand (3aza-APL) that mimic myelin basic protein (MBP), also decreased the incidence of EAE, disease severity, infiltration of inflammatory cells, and protected myelin. A reduction in inflammatory T-cells with an increase in Tregs and myeloid suppressor cells is also found in EAE mice treated with SNJ1945 and 3aza-APL. Thus, a novel combination strategy was tested in chronic EAE mouse model in B10 mice which showed multiple pathological mechanisms could be addressed by simultaneous treatment with calpain inhibitor SNJ1945 and protease-resistant 3aza-APL to achieve a stronger therapeutic effect.

Design, Synthesis and Evaluation of Antioxidant and NSAID Derivatives with Antioxidant, Anti-Inflammatory and Plasma Lipid Lowering Effects

Amides containing methyl esters of γ-aminobutyric acid (GABA), L-proline and L-tyrosine, and esters containing 3-(pyridin-3-yl)propan-1-ol were synthesized by conjugation with 3,5-di-tert-butyl-4-hydroxybenzoic, an NSAID (tolfenamic acid), or 3-phenylacrylic (cinnamic, (E)-3-(3,4-dimethoxyphenyl)acrylic and caffeic) acids. The rationale for the conjugation of such moieties was based on the design of structures with two or more molecular characteristics. The novel compounds were tested for their antioxidant, anti-inflammatory and hypolipidemic properties. Several compounds were potent antioxidants, comparable to the well-known antioxidant, Trolox. In addition, the radical scavenging activity of compound 6 reached levels that were slightly better than that of Trolox. All the tested compounds demonstrated remarkable activity in the reduction in carrageenan-induced rat paw edema, up to 59% (compound 2, a dual antioxidant and anti-inflammatory molecule, with almost 2.5-times higher activity in this experiment than the parent NSAID). Additionally, the compounds caused a significant decrease in the plasma lipidemic indices in Triton-induced hyperlipidemic rats. Compound 2 decreased total cholesterol by 75.1% and compound 3 decreased triglycerides by 79.3% at 150 μmol/kg (i.p.). The hypocholesterolemic effect of the compounds was comparable to that of simvastatin, a well-known hypocholesterolemic drug. Additionally, all compounds lowered blood triglycerides. The synthesized compounds with multiple activities, as designed, may be useful as potential candidates for conditions involving inflammation, lipidemic deregulation and oxygen toxicity.

Potential clinical implications of molecular mimicry-induced autoimmunity

BACKGROUND

Molecular mimicry is hypothesized to be a mechanism by which autoimmune diseases are triggered. It refers to sequence or structural homology between foreign antigens and self-antigens, which can activate cross-reactive lymphocytes that attack host tissues. Elucidating the role of molecular mimicry in human autoimmunity could have important clinical implications.

OBJECTIVE

To review evidence for the role of molecular mimicry in major autoimmune diseases and discuss potential clinical implications.

METHODS

Comprehensive literature review of clinical trials, observational studies, animal models, and immunology studies on molecular mimicry in multiple sclerosis, type 1 diabetes, rheumatoid arthritis, lupus, Guillain-Barre syndrome, autoimmune myocarditis, and primary biliary cirrhosis published from 2000-2023.

RESULTS

Substantial indirect evidence supports molecular mimicry as a contributor to loss of self-tolerance in several autoimmune conditions. Proposed microbial triggers include Epstein-Barr virus, coxsackievirus, Campylobacter jejuni, and bacterial commensals. Key mechanisms involve cross-reactive T cells and autoantibodies induced by epitope homology between microbial and self-antigens. Perpetuation of autoimmunity involves epitope spreading, inflammatory mediators, and genetic factors.

CONCLUSIONS

Molecular mimicry plausibly explains initial stages of autoimmune pathogenesis induced by infection or microbiota disturbances. Understanding mimicry antigens and pathways could enable improved prediction, monitoring, and antigen-specific immunotherapy for autoimmune disorders. However, definitive proof of causation in humans remains limited. Further research should focus on establishing clinical evidence and utility.

The immunomodulatory roles of the gut microbiome in autoimmune diseases of the central nervous system: Multiple sclerosis as a model

The gut-associated lymphoid tissue is a primary activation site for immune responses to infection and immunomodulation. Experimental evidence using animal disease models suggests that specific gut microbes significantly regulate inflammation and immunoregulatory pathways. Furthermore, recent clinical findings indicate that gut microbes' composition, collectively named gut microbiota, is altered under disease state. This review focuses on the functional mechanisms by which gut microbes promote immunomodulatory responses that could be relevant in balancing inflammation associated with autoimmunity in the central nervous system. We also propose therapeutic interventions that target the composition of the gut microbiota as immunomodulatory mechanisms to control neuroinflammation.

Exploring the Role of Neurotransmitters in Multiple Sclerosis: An Expanded Review

Multiple sclerosis (MS) is a chronic inflammatory and neurodegenerative disease of the central nervous system (CNS). Although emerging evidence has shown that changes in neurotransmitter levels in the synaptic gap may contribute to the pathophysiology of MS, their specific role has not been elucidated yet. In this review, we aim to analyze preclinical and clinical evidence on the structural and functional changes in neurotransmitters in MS and critically discuss their potential role in MS pathophysiology. Preclinical studies have demonstrated that alterations in glutamate metabolism may contribute to MS pathophysiology, by causing excitotoxic neuronal damage. Dysregulated interaction between glutamate and GABA results in synaptic loss. The GABAergic system also plays an important role, by regulating the activity and plasticity of neural networks. Targeting GABAergic/glutamatergic transmission may be effective in fatigue and cognitive impairment in MS. Acetylcholine (ACh) and dopamine can also affect the T-mediated inflammatory responses, thereby being implicated in MS-related neuroinflammation. Also, melatonin might affect the frequency of relapses in MS, by regulating the sleep-wake cycle. Increased levels of nitric oxide in inflammatory lesions of MS patients may be also associated with axonal neuronal degeneration. Therefore, neurotransmitter imbalance may be critically implicated in MS pathophysiology, and future studies are needed for our deeper understanding of their role in MS.

The GABA and GABA-Receptor System in Inflammation, Anti-Tumor Immune Responses, and COVID-19

GABA and GABA_A-receptors (GABA_A-Rs) play major roles in neurodevelopment and neurotransmission in the central nervous system (CNS). There has been a growing appreciation that GABA_A-Rs are also present on most immune cells. Studies in the fields of autoimmune disease, cancer, parasitology, and virology have observed that GABA-R ligands have anti-inflammatory actions on T cells and antigen-presenting cells (APCs), while also enhancing regulatory T cell (Treg) responses and shifting APCs toward anti-inflammatory phenotypes. These actions have enabled GABA_A-R ligands to ameliorate autoimmune diseases, such as type 1 diabetes (T1D), multiple sclerosis (MS), and rheumatoid arthritis, as well as type 2 diabetes (T2D)-associated inflammation in preclinical models. Conversely, antagonism of GABA_A-R activity promotes the pro-inflammatory responses of T cells and APCs, enhancing anti-tumor responses and reducing tumor burden in models of solid tumors. Lung epithelial cells also express GABA-Rs, whose activation helps maintain fluid homeostasis and promote recovery from injury. The ability of GABA_A-R agonists to limit both excessive immune responses and lung epithelial cell injury may underlie recent findings that GABA_A-R agonists reduce the severity of disease in mice infected with highly lethal coronaviruses (SARS-CoV-2 and MHV-1). These observations suggest that GABA_A-R agonists may provide off-the-shelf therapies for COVID-19 caused by new SARS-CoV-2 variants, as well as novel beta-coronaviruses, which evade vaccine-induced immune responses and antiviral medications. We review these findings and further advance the notions that (1) immune cells possess GABA_A-Rs to limit inflammation in the CNS, and (2) this natural "braking system" on inflammatory responses may be pharmacologically engaged to slow the progression of autoimmune diseases, reduce the severity of COVID-19, and perhaps limit neuroinflammation associated with long COVID.

A GABA-receptor agonist reduces pneumonitis severity, viral load, and death rate in SARS-CoV-2-infected mice

Gamma-aminobutyric acid (GABA) and GABA-receptors (GABA-Rs) form a major neurotransmitter system in the brain. GABA-Rs are also expressed by 1) cells of the innate and adaptive immune system and act to inhibit their inflammatory activities, and 2) lung epithelial cells and GABA-R agonists/potentiators have been observed to limit acute lung injuries. These biological properties suggest that GABA-R agonists may have potential for treating COVID-19. We previously reported that GABA-R agonist treatments protected mice from severe disease induced by infection with a lethal mouse coronavirus (MHV-1). Because MHV-1 targets different cellular receptors and is biologically distinct from SARS-CoV-2, we sought to test GABA therapy in K18-hACE2 mice which develop severe pneumonitis with high lethality following SARS-CoV-2 infection. We observed that GABA treatment initiated immediately after SARS-CoV-2 infection, or 2 days later near the peak of lung viral load, reduced pneumonitis severity and death rates in K18-hACE2 mice. GABA-treated mice had reduced lung viral loads and displayed shifts in their serum cytokine/chemokine levels that are associated with better outcomes in COVID-19 patients. Thus, GABA-R activation had multiple effects that are also desirable for the treatment of COVID-19. The protective effects of GABA against two very different beta coronaviruses (SARS-CoV-2 and MHV-1) suggest that it may provide a generalizable off-the-shelf therapy to help treat diseases induced by new SARS-CoV-2 variants and novel coronaviruses that evade immune responses and antiviral medications. GABA is inexpensive, safe for human use, and stable at room temperature, making it an attractive candidate for testing in clinical trials. We also discuss the potential of GABA-R agonists for limiting COVID-19-associated neuroinflammation.

Homotaurine ameriolates the core ASD symptomatology in VPA rats through GABAergic signalling: Role of GAD67

Dysregulated GABAergic signaling is reported in Autism Spectrum disorder (ASD). In the present study, we evaluated a GABA structural mimicker homotaurine (HT) via in-silico docking and investigated the therapeutic efficacy of this drug to ameliorate ASD symptoms in the valproic acid (VPA) rat model of ASD. For the in-vivo study, animals were divided into two groups [Normal control (NC, 0.9% saline; i.p) and disease control (VPA 600mg/kg; i.p)] on gestational day (GD) 12.5. Male pups from VPA-exposed mothers were further divided into five groups (n=6 in each group): disease control (DC, no-further treatment), standard treatment (risperidone (RES) 2.5mg/kg; i.p, consecutively from PND 23-43), HT (10, 25 and 50mg/kg; i.p, consecutively from PND 23-43). In in-silico studies, the binding pattern of homotaurine to GABA-A receptor was found similar to GABA with Tyr205, Glu155, Tyr157, Arg6, and Thr 130 as shared residues. In the in-vivo phase, the early developmental parameters (from PND 7-23) and behavioral parameters (from PND 43-54) were assessed. The offspring of the VPA exposed group exhibited significant (p<0.05) developmental delays, behavioral deficits [decreased sociability and social novelty (three-chamber sociability test), spatial memory (Morris water maze), increased stereotypy (self-grooming)], increased oxidative stress (decreased GSH, SOD, Catalase, and increased MDA), increased pro-inflammatory (IL-1β, 6, TNF-α) and decreased anti-inflammatory (IL-10) cytokines, Purkinje cell loss in the cerebellum and pyknosis in PFC (H/E, Nissil staining) and decreased GAD67 expression in the cerebellum (RT-PCR & immunohistochemistry). Compared to the DC, HT treatment (50mg/kg) was able to ameliorate the aberrant core behavioral deficits, decreased oxidative stress, decreased pro-inflammatory and increased anti-inflammatory cytokine profile with preservation of the Purkinje cell density in the cerebellum, decreased pyknosis in the prefrontal cortex and normalised the expression of GAD67. Thus, HT can be a useful therapeutic agent in ASD and requires further clinical evaluation.

IL-33 and IL-10 Serum Levels Increase in MCI Patients Following Homotaurine Treatment

Homotaurine is a potential therapeutic compound for treatment of Alzheimer’s disease (AD), but its efficacy is still under investigation. Emerging data have shown that other than neuroprotective, homotaurine is endowed with anti-inflammatory activities, though with still unclear underlying mechanisms. Inflammation plays a critical role in the pathogenesis of AD and we previously suggested that homotaurine supplementation in patients with amnestic mild cognitive impairment (MCI) plays beneficial effects associated to a decrease in the circulating levels of the pro-inflammatory cytokine IL-18. Here we report that MCI patients supplemented with homotaurine for 12 months show elevated serum levels of IL-10 and IL-33, as compared to baseline, in addition to the described IL-18 decrease. Furthermore, we observed a significant positive correlation between IL-10 and IL-33 levels after treatment but not at the baseline, underlining the effectiveness of the compound in modulating both cytokines in an inter-related fashion and in regulating the pro/anti-inflammation balance. Furthermore, the elevation of both IL-10 and IL-33 is significantly associated with an improvement of episodic memory of treated patients, as measured by the Delayed Verbal Ray Test. In conclusion, our results confirm that homotaurine treatment exerts an overall anti-inflammatory action in MCI patients, based not only on the down-regulation of pro-inflammatory IL-18, but also on up-regulation of the anti-inflammatory IL-33 and IL-10 cytokines, which in turn are associated with an amelioration of patient’s cognitive functions. Future studies should be addressed to investigate the molecular mechanisms of homotaurine anti-inflammatory activity and its therapeutic exploitation in early AD.

Fecal microbiota transplantation is safe and tolerable in patients with multiple sclerosis: A pilot randomized controlled trial

Background

Patients with MS have an altered gut microbiota compared to healthy individuals, as well as elevated small intestinal permeability, which may be contributing to the development and progression of the disease.

Objective

We sought to investigate if fecal microbiota transplantation was safe and tolerable in MS patients and if it could improve abnormal intestinal permeability.

Methods

Nine patients with MS were recruited and provided monthly FMTs for up to six months. The primary outcome investigated was change in peripheral blood cytokine concentrations. The secondary outcomes were gut microbiota composition, intestinal permeability, and safety (assessed with EDSS and MRI).

Results

The study was terminated early and was subsequently underpowered to assess whether peripheral blood cytokines were altered following FMTs. FMTs were safe in this group of patients. Two of five patients had elevated small intestinal permeability at baseline that improved to normal values following FMTs. Significant, donor-specific, beneficial alterations to the MS patient gut microbiota were observed following FMT.

Conclusion

FMT was safe and tolerable in this cohort of RRMS patients, may improve elevated small intestinal permeability, and has the potential to enrich for an MS-protective microbiota. Further studies with longer follow-up and larger sample sizes are required to determine if FMT is a suitable therapy for MS.

GABA Administration Ameliorates Sjogren’s Syndrome in Two Different Mouse Models

Sjögren’s syndrome (SS) is a chronic autoimmune disease characterized by lymphocytic infiltrates in the salivary and lachrymal glands resulting in oral and ocular dryness. There are no clinically approved therapies to slow the progression of SS. Immune cells possess receptors for the neurotransmitter GABA (GABA-Rs) and their activation has immunoregulatory actions. We tested whether GABA administration has potential for amelioration of SS in NOD.B10-H2^b and C57BL/6.NOD-Aec1Aec2 mice, two spontaneous SS models. Oral GABA treatment was initiated (1) after the development of sialadenitis but before the onset of overt symptoms, or (2) after the appearance of overt symptoms. When assessed weeks later, GABA-treated mice had greater saliva and tear production, as well as quicker times to salvia flow, in both SS mouse models. This was especially evident when GABA treatment was initiated after the onset of overt disease. This preservation of exocrine function was not accompanied by significant changes in the number or area of lymphocytic foci in the salivary or lachrymal glands of GABA-treated mice and we discuss the possible reasons for these observations. Given that GABA-treatment preserved saliva and tear production which are the most salient symptoms of SS and is safe for consumption, it may provide a new approach to help ameliorate SS.

The Role of Supplementation with Natural Compounds in Post-Stroke Patients

Malnutrition is a serious problem in post-stroke patients. Importantly, it intensifies with hospitalization, and is related to both somatic and psychological reasons, as well as is associated with the insufficient knowledge of people who accompany the patient. Malnutrition is a negative prognostic factor, leading to a reduction in the quality of life. Moreover, this condition significantly extends hospitalization time, increases the frequency of treatment in intensive care units, and negatively affects the effectiveness of rehabilitation. Obtaining growing data on the therapeutic effectiveness of new compounds of natural origin is possible through the use of pharmacodynamic and analytical methods to assess their therapeutic properties. The proper supply of nutrients, as well as compounds of natural origin, is an important element of post-stroke therapy, due to their strong antioxidant, anti-inflammatory, neuroprotective and neuroplasticity enhancing properties. Taking the above into account, in this review we present the current state of knowledge on the benefits of using selected substances of natural origin in patients after cerebral stroke.