NLRP3 inflammasome is associated with the response to IFN-β in patients with multiple sclerosis

NLRP3 polymorphisms and response to interferon-beta in multiple sclerosis patients

We aimed to investigate whether NLR family, pyrin domain containing 3 (NLRP3) polymorphisms are associated with the response to interferon-beta (IFNβ) in multiple sclerosis (MS) patients. A total of 14 NLRP3 polymorphisms were genotyped in a cohort of 665 relapsing-remitting MS patients recruited across 5 centers and classified into responders and non-responders according to clinical-radiological criteria after 1 year of IFNβ treatment. A meta-analysis failed to demonstrate significant associations between the response to IFNβ and NLRP3 polymorphisms. These findings do not support a role of polymorphisms located in the NLRP3 gene and the response to IFNβ in MS patients.

Elongator mutation in mice induces neurodegeneration and ataxia-like behavior

Cerebellar ataxias are severe neurodegenerative disorders with an early onset and progressive and inexorable course of the disease. Here, we report a single point mutation in the gene encoding Elongator complex subunit 6 causing Purkinje neuron degeneration and an ataxia-like phenotype in the mutant wobbly mouse. This mutation destabilizes the complex and compromises its function in translation regulation, leading to protein misfolding, proteotoxic stress, and eventual neuronal death. In addition, we show that substantial microgliosis is triggered by the NLRP3 inflammasome pathway in the cerebellum and that blocking NLRP3 function in vivo significantly delays neuronal degeneration and the onset of ataxia in mutant animals. Our data provide a mechanistic insight into the pathophysiology of a cerebellar ataxia caused by an Elongator mutation, substantiating the increasing body of evidence that alterations of this complex are broadly implicated in the onset of a number of diverse neurological disorders.

Elp6 is a component of the Elongator complex that regulates tRNAs and translation. Here the authors identify a mutation in the Elp6 gene that contributes to the cerebellar ataxia-like phenotype in a mutant mouse.

Multiple Immune-Inflammatory and Oxidative and Nitrosative Stress Pathways Explain the Frequent Presence of Depression in Multiple Sclerosis

Patients with a diagnosis of multiple sclerosis (MS) or major depressive disorder (MDD) share a wide array of biological abnormalities which are increasingly considered to play a contributory role in the pathogenesis and pathophysiology of both illnesses. Shared abnormalities include peripheral inflammation, neuroinflammation, chronic oxidative and nitrosative stress, mitochondrial dysfunction, gut dysbiosis, increased intestinal barrier permeability with bacterial translocation into the systemic circulation, neuroendocrine abnormalities and microglial pathology. Patients with MS and MDD also display a wide range of neuroimaging abnormalities and patients with MS who display symptoms of depression present with different neuroimaging profiles compared with MS patients who are depression-free. The precise details of such pathology are markedly different however. The recruitment of activated encephalitogenic Th17 T cells and subsequent bidirectional interaction leading to classically activated microglia is now considered to lie at the core of MS-specific pathology. The presence of activated microglia is common to both illnesses although the pattern of such action throughout the brain appears to be different. Upregulation of miRNAs also appears to be involved in microglial neurotoxicity and indeed T cell pathology in MS but does not appear to play a major role in MDD. It is suggested that the antidepressant lofepramine, and in particular its active metabolite desipramine, may be beneficial not only for depressive symptomatology but also for the neurological symptoms of MS. One clinical trial has been carried out thus far with, in particular, promising MRI findings.

Targeting the NLRP3 inflammasome in inflammatory diseases

Danger signals are a hallmark of many common inflammatory diseases, and these stimuli can function to activate the cytosolic innate immune signalling receptor NLRP3 (NOD-, LRR- and pyrin domain-containing 3). Once activated, NLRP3 nucleates the assembly of an inflammasome, leading to caspase 1-mediated proteolytic activation of the interleukin-1β (IL-1β) family of cytokines, and induces an inflammatory, pyroptotic cell death. Pharmacological inhibition of NLRP3 activation results in potent therapeutic effects in a wide variety of rodent models of inflammatory diseases, effects that are mirrored by genetic ablation of NLRP3. Although these findings highlight the potential of NLRP3 as a drug target, an understanding of NLRP3 structure and activation mechanisms is incomplete, which has hampered the discovery and development of novel therapeutics against this target. Here, we review recent advances in our understanding of NLRP3 activation and regulation, highlight the evolving landscape of NLRP3 modulators and discuss opportunities for pharmacologically targeting NLRP3 with novel small molecules.

Is Targeting the Inflammasome a Way Forward for Neuroscience Drug Discovery?

Neuroinflammation is becoming increasingly recognized as a critical factor in the pathology of both acute and chronic neurological conditions. Inflammasomes such as the one formed by NACHT, LRR, and PYD domains containing protein 3 (NLRP3) are key regulators of inflammation due to their ability to induce the processing and secretion of interleukin 1β (IL-1β). IL-1β has previously been identified as a potential therapeutic target in a variety of conditions due to its ability to promote neuronal damage under conditions of injury. Thus, inflammasome inhibition has the potential to curtail inflammatory signaling, which could prove beneficial in certain diseases. In this review, we discuss the evidence for inflammasome contributions to the pathology of neurodegenerative conditions such as Alzheimer's disease and Parkinson's disease, epilepsy, and acute degeneration following brain trauma or stroke. In addition, we review the current landscape of drug development targeting the NLRP3 inflammasome.

Association of NLRP3 single nucleotide polymorphisms with ulcerative colitis: A case-control study

BACKGROUND

Ulcerative colitis (UC) is inflammatory bowel disease (IBD), characterized by chronic inflammation episodes within mucosal layer of the intestine mostly affecting colon and rectum. As the role of innate immunity in pathogenesis of disease and important role of NLRP3, the aim of this study is to investigate the association of NLRP3 SNPs with UC in Iranian patients.

METHODS

Blood samples from 45 UC patients and 56 healthy subjects were tested for single nucleotide polymorphisms in rs10754558, rs3806265, rs4612666, and rs35829419 of NLRP3 gene, using real-time PCR method.

RESULTS

Among the investigated SNPs, "GG" genotype of rs10754558 have been 2.48 times more common among UC patients (P=0.04), while "CG" genotype has indicated protective effect against UC, as more frequently found in healthy subjects.

CONCLUSION

Despite no significant association between three investigated SNPs and disease, "GG" and "CG" genotypes of rs10754558 have been significantly associated with disease.

Role of Inflammasomes in Neuroimmune and Neurodegenerative Diseases: A Systematic Review

Inflammasomes are multiprotein complexes that can sense pathogen-associated molecular patterns and damage-associated molecular signals. They are involved in the initiation and development of inflammation via activation of IL-1β and IL-18. Many recent studies suggest a strong correlation between inflammasomes and neurological diseases, such as multiple sclerosis (MS), Alzheimer's disease (AD), and Parkinson's disease (PD). Several components of inflammasomes, such as nucleotide-binding oligomerization domain- (NOD-) like receptor, absent in melanoma 2- (AIM2-) like receptors (ALRs), apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), and caspase-1, as well as the upstream factors and downstream effectors, are associated with the initiation and development of MS and its animal model, experimental autoimmune encephalomyelitis. Additionally, inflammasomes affect the efficacy of interferon-β therapy in patients with MS. Finally, the strong association of inflammasomes with AD and PD needs to be further studied. In this review of latest literatures, we comprehensively tease out diverse roles of different kinds of inflammasomes in neuroimmune and neurodegenerative diseases, especially in the perspective of double roles involved in pathogenesis, and identify future research priorities.

Inflammasome activation in multiple sclerosis and experimental autoimmune encephalomyelitis (EAE)

The aptly named inflammasomes are powerful signaling complexes that sense inflammatory signals under a myriad of conditions, including those from infections and endogenous sources. The inflammasomes promote inflammation by maturation and release of the pro-inflammatory cytokines, IL-1β and IL-18. Several inflammasomes have been identified so far, but this review focuses mainly on the NLRP3 inflammasome. By still ill-defined activation mechanisms, a sensor molecule, NLRP3 (NACHT, LRR and PYD domains-containing protein 3), responds to danger signals and rapidly recruits ASC (apoptosis-associated speck-like protein containing a CARD) and pro-caspase-1 to form a large oligomeric signaling platform-the inflammasome. Involvement of the NLRP3 inflammasome in infections, metabolic disorders, autoinflammation, and autoimmunity, underscores its position as a central player in sensing microbial and damage signals and coordinating pro-inflammatory immune responses. Indeed, evidence in patients with multiple sclerosis (MS) suggests inflammasome activation occurs during disease. Experiments with the mouse model of MS, experimental autoimmune encephalomyelitis (EAE), specifically describe the NLRP3 inflammasome as critical and necessary to disease development. This review discusses recent studies in EAE and MS which describe associations of inflammasome activation with promotion of T cell pathogenicity, infiltration of cells into the central nervous system (CNS) and direct neurodegeneration during EAE and MS.

The inflammasome: an emerging therapeutic oncotarget for cancer prevention

Deregulated inflammation is considered to be one of the hallmarks of cancer initiation and development regulation. Emerging evidence indicates that the inflammasome plays a central role in regulating immune cells and cytokines related to cancer. The inflammasome is a multimeric complex consisting of NOD-like receptors (NLRs) and responds to a variety of endogenous (damage-associated molecular patterns) and exogenous (pathogen-associated molecular patterns) stimuli. Several lines of evidence suggests that in cancer the inflammasome is positively associated with characteristics such as elevated levels of IL-1β and IL-18, activation of NF-κB signaling, enhanced mitochondrial oxidative stress, and activation of autophagic process. A number of NLRs, such as NLRP3 and NLRC4 are also highlighted in carcinogenesis and closely correlate to chemoresponse and prognosis. Although conflicting evidence suggested the duplex role of inflammasome in cancer development, the phenomenon might be attributed to NLRs difference, cell and tissue type, cancer stage, and specific experimental conditions. Given the promising role of inflammasome in mediating cancer development, precise elucidation of its signaling network and pathological significance may lead to novel therapeutic options for malignancy therapy and prevention.

NLR-Dependent Regulation of Inflammation in Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) associated with inappropriate activation of lymphocytes, hyperinflammatory responses, demyelination, and neuronal damage. In the past decade, a number of biological immunomodulators have been developed that suppress the peripheral immune responses and slow down the progression of the disease. However, once the inflammation of the CNS has commenced, it can cause serious permanent neuronal damage. Therefore, there is a need for developing novel therapeutic approaches that control and regulate inflammatory responses within the CNS. Nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) are intracellular regulators of inflammation expressed by many cell types within the CNS. They redirect multiple signaling pathways initiated by pathogens and molecules released by injured tissues. NLR family members include positive regulators of inflammation, such as NLRP3 and NLRC4 and anti-inflammatory NLRs, such as NLRX1 and NLRP12. They exert immunomodulatory effect at the level of peripheral immune responses, including antigen recognition and lymphocyte activation and differentiation. Also, NLRs regulate tissue inflammatory responses. Understanding the molecular mechanisms that are placed at the crossroad of innate and adaptive immune responses, such as NLR-dependent pathways, could lead to the discovery of new therapeutic targets. In this review, we provide a summary of the role of NLRs in the pathogenesis of MS. We also summarize how anti-inflammatory NLRs regulate the immune response within the CNS. Finally, we speculate the therapeutic potential of targeting NLRs in MS.

Shifting paradigms in multiple sclerosis: from disease-specific, through population-specific toward patient-specific

PURPOSE OF REVIEW

In recent years we notice paradigm shifts in the understanding of multiple sclerosis (MS), leading to important transition in the patients' management. This review discusses some of the recent findings and developments underlying the conceptual changes being translated from 'treating the disease' to 'treating the patient' with MS (PwMS).

RECENT FINDINGS

Applying advanced technologies combined with cross-disciplinary efforts in the fields of neuropathology, neuroimmunology, neurobiology, and neuroimaging, together with clinical neurology provided support for the notion that MS is not a single disease but rather a spectrum. Predictive markers of disease subtypes, disease activity and response to therapy are being developed; some already applied to practice, allowing informed management. In parallel, population-specific issues, some genetic-driven, others caused by environmental (sun-exposure, life-style, etc.), gender-related (hormones) and epigenetic factors, are being elucidated. Additionally, patient empowerment-based approaches, including integration of patient-reported outcome measures (PRO) as well as tools to enhance patients' adherence to medications, are being developed, some already provided as part of emerging mobile-health technologies.

SUMMARY

Developments in the MS field, elucidating disease subtypes and interpopulation diversities, together with integration of patient-centered approaches, allow transition toward precision medicine in MS clinical trials and patient care.

Inflammasome and Cancer

The current chapter focuses on the role of inflammasome in cancer prevention and development. Emerging evidence suggested that inflammasome is closely correlated with elevated levels of IL-1β and IL-18, activation of NF-κB signaling, enhanced mitochondrial oxidative stress, and activation of autophagic process in cancer. Meanwhile, inflammasome component NOD-like receptors (NLRs) are also involved in carcinogenesis and closely correlated to chemoresponse and prognosis. Although several lines indicated the duplex role of inflammasome in cancer development, the phenomenon might be attributed to NLR difference, cell and tissue type, cancer stage, and specific experimental conditions. Designation of inflammasome targeting strategy has become a novel tool for cancer prevention or treatment.

Tyrosine phosphatase SHP2 negatively regulates NLRP3 inflammasome activation via ANT1-dependent mitochondrial homeostasis

Aberrant activation of NLRP3 inflammasome has an important function in the pathogenesis of various inflammatory diseases. Although many components and mediators of inflammasome activation have been identified, how NLRP3 inflammasome is regulated to prevent excessive inflammation is unclear. Here we show NLRP3 inflammasome stimulators trigger Src homology-2 domain containing protein tyrosine phosphatase-2 (SHP2) translocation to the mitochondria, to interact with and dephosphorylate adenine nucleotide translocase 1 (ANT1), a central molecule controlling mitochondrial permeability transition. This mechanism prevents collapse of mitochondrial membrane potential and the subsequent release of mitochondrial DNA and reactive oxygen species, thus preventing hyperactivation of NLRP3 inflammasome. Ablation or inhibition of SHP2 in macrophages causes intensified NLRP3 activation, overproduction of proinflammatory cytokines IL-1β and IL-18, and increased sensitivity to peritonitis. Collectively, our data highlight that, by inhibiting ANT1 and mitochondrial dysfunction, SHP2 orchestrates an intrinsic regulatory loop to limit excessive NLRP3 inflammasome activation.

Activating α7 nicotinic acetylcholine receptor inhibits NLRP3 inflammasome through regulation of β-arrestin-1

AIMS

To evaluate whether activating α7 nicotinic acetylcholine receptor (α7nAChR) could inhibit the NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome through regulation of β-arrestin-1 in monocyte/macrophage system, thus contributing to the control of neuroinflammation.

METHODS

The protein levels of NLRP3, caspase-1 (Casp-1) p20 and proCasp-1, interleukin-1β (IL-1β) p17 and proIL-1β, IL-18 and proIL-18 were measured using Western blotting. The mRNA levels of Casp-1 and IL-1β were detected by real-time PCR (RT-PCR). The colocalization and interaction of NLRP3 protein and β-arrestin-1 were measured by immunofluorescence staining and immunoprecipitation.

RESULTS

The expression of β-arrestin-1 was significantly increased and colocalized with CD45-positive cells in spinal cord of experimental auto-immune encephalomyelitis (EAE) mice when compared with the sham mice, which was attenuated by pretreatment with PNU282987, a specific α7nAChR agonist. PNU282987 also significantly inhibited the activation of NLRP3 inflammasome and thus decreased the production of IL-1β and IL-18 both in lipopolysaccharide (LPS)/ATP-stimulated BV2 microglia in vitro and spinal cord from EAE mice in vivo, while inverse effects were observed in α7nAChR knockout mice. Furthermore, overexpression of β-arrestin-1 attenuated the inhibitory effect of PNU282987 on NLRP3 inflammasome activation in LPS/ATP-stimulated BV2 microglia. PNU282987 inhibited the interaction between β-arrestin-1 and NLRP3 protein in vitro.

CONCLUSIONS

The present study demonstrates that activating α7nAChR can lead to NLRP3 inflammasome inhibition via regulation of β-arrestin-1 in monocyte/microglia system.

Identification of rare genetic variation of NLRP1 gene in familial multiple sclerosis

The genetic etiology and the contribution of rare genetic variation in multiple sclerosis (MS) has not yet been elucidated. Although familial forms of MS have been described, no convincing rare and penetrant variants have been reported to date. We aimed to characterize the contribution of rare genetic variation in familial and sporadic MS and have identified a family with two sibs affected by concomitant MS and malignant melanoma (MM). We performed whole exome sequencing in this primary family and 38 multiplex MS families and 44 sporadic MS cases and performed transcriptional and immunologic assessment of the identified variants. We identified a potentially causative homozygous missense variant in NLRP1 gene (Gly587Ser) in the primary family. Further possibly pathogenic NLRP1 variants were identified in the expanded cohort of patients. Stimulation of peripheral blood mononuclear cells from MS patients with putatively pathogenic NLRP1 variants showed an increase in IL-1B gene expression and active cytokine IL-1β production, as well as global activation of NLRP1-driven immunologic pathways. We report a novel familial association of MS and MM, and propose a possible underlying genetic basis in NLRP1 gene. Furthermore, we provide initial evidence of the broader implications of NLRP1-related pathway dysfunction in MS.

Modulating inflammation and neuroprotection in multiple sclerosis

Multiple sclerosis (MS) is a neurological disorder of the central nervous system with a presentation and disease course that is largely unpredictable. MS can cause loss of balance, impaired vision or speech, weakness and paralysis, fatigue, depression, and cognitive impairment. Immunomodulation is a major target given the appearance of focal demyelinating lesions in myelin-rich white matter, yet progression and an increasing appreciation for gray matter involvement, even during the earliest phases of the disease, highlights the need to afford neuroprotection and limit neurodegenerative processes that correlate with disability. This review summarizes key aspects of MS pathophysiology and histopathology with a focus on neuroimmune interactions in MS, which may facilitate neurodegeneration through both direct and indirect mechanisms. There is a focus on processes thought to influence disease progression and the role of oxidative stress and mitochondrial dysfunction in MS. The goals and efficacy of current disease-modifying therapies and those in the pipeline are discussed, highlighting recent advances in our understanding of pathways mediating disease progression to identify and translate both immunomodulatory and neuroprotective therapeutics from the bench to the clinic.

PINK1/Parkin-Dependent Mitochondrial Surveillance: From Pleiotropy to Parkinson's Disease

Parkinson's disease (PD) is one of the most frequent neurodegenerative disease caused by the preferential, progressive degeneration of the dopaminergic (DA) neurons of the substantia nigra (SN) pars compacta. PD is characterized by a multifaceted pathological process involving protein misfolding, mitochondrial dysfunction, neuroinflammation and metabolism deregulation. The molecular mechanisms governing the complex interplay between the different facets of this process are still unknown. PARK2/Parkin and PARK6/PINK1, two genes responsible for familial forms of PD, act as a ubiquitous core signaling pathway, coupling mitochondrial stress to mitochondrial surveillance, by regulating mitochondrial dynamics, the removal of damaged mitochondrial components by mitochondria-derived vesicles, mitophagy, and mitochondrial biogenesis. Over the last decade, PINK1/Parkin-dependent mitochondrial quality control emerged as a pleiotropic regulatory pathway. Loss of its function impinges on a number of physiological processes suspected to contribute to PD pathogenesis. Its role in the regulation of innate immunity and inflammatory processes stands out, providing compelling support to the contribution of non-cell-autonomous immune mechanisms in PD. In this review, we illustrate the central role of this multifunctional pathway at the crossroads between mitochondrial stress, neuroinflammation and metabolism. We discuss how its dysfunction may contribute to PD pathogenesis and pinpoint major unresolved questions in the field.

Stress-Induced NLRP3 Inflammasome in Human Diseases

Stress is a complex event that induces disturbances to physiological and psychological homeostasis, and it may have a detrimental impact on certain brain and physiological functions. In the last years, a dual role of the stress effect has been studied in order to elucidate the molecular mechanism by which can induce physiological symptoms after psychological stress exposition and vice versa. In this sense, inflammation has been proposed as an important starring. And in the same line, the inflammasome complex has emerged to give responses because of its role of stress sensor. The implication of the same complex, NLRP3 inflammasome, in different diseases such as cardiovascular, neurodegenerative, psychiatric, and metabolic diseases opens a door to develop new therapeutic perspectives.

AIM 2 inflammasomes regulate neuronal morphology and influence anxiety and memory in mice

Inflammasomes are the protein assemblies that consist of inflammasome sensors, adaptor apoptosis-associated speck-like proteins containing a CARD (ASC) and inflammasome caspase. Inflammasomes sense multiple danger signals via various inflammasome sensors and consequently use caspase to trigger proteolytic processing and secretion of IL-1β cytokines. Recent studies have suggested that neurons use their own innate immune system to detect danger signals and regulate neuronal morphology. Here, we investigate whether inflammasomes, the critical components of innate immunity, participate in regulation of neuronal morphology and function. Among various sensors, Absent in melanoma 2 (Aim2) expression in neurons is most prominent. Adding synthetic double-stranded DNA (dsDNA) to cultured neurons induces IL-1β secretion in an AIM2-dependent manner and consequently downregulates dendritic growth but enhances axon extension. The results of Aim2 knockout and knockdown show that AIM2 acts cell-autonomously to regulate neuronal morphology. Behavioral analyses further reveal that Aim2-/- mice exhibit lower locomotor activity, increased anxious behaviors and reduced auditory fear memory. In conclusion, our study suggests that AIM2 inflammasomes regulate neuronal morphology and influence mouse behaviors.

Meta-Analysis of Differential Connectivity in Gene Co-Expression Networks in Multiple Sclerosis

Differential gene expression analyses to investigate multiple sclerosis (MS) molecular pathogenesis cannot detect genes harboring genetic and/or epigenetic modifications that change the gene functions without affecting their expression. Differential co-expression network approaches may capture changes in functional interactions resulting from these alterations. We re-analyzed 595 mRNA arrays from publicly available datasets by studying changes in gene co-expression networks in MS and in response to interferon (IFN)-β treatment. Interestingly, MS networks show a reduced connectivity relative to the healthy condition, and the treatment activates the transcription of genes and increases their connectivity in MS patients. Importantly, the analysis of changes in gene connectivity in MS patients provides new evidence of association for genes already implicated in MS by single-nucleotide polymorphism studies and that do not show differential expression. This is the case of amiloride-sensitive cation channel 1 neuronal (ACCN1) that shows a reduced number of interacting partners in MS networks, and it is known for its role in synaptic transmission and central nervous system (CNS) development. Furthermore, our study confirms a deregulation of the vitamin D system: among the transcription factors that potentially regulate the deregulated genes, we find TCF3 and SP1 that are both involved in vitamin D3-induced p27Kip1 expression. Unveiling differential network properties allows us to gain systems-level insights into disease mechanisms and may suggest putative targets for the treatment.

Interferons and inflammasomes: Cooperation and counterregulation in disease

Interferons and the IL-1 family of cytokines have important roles in host defense against invading viruses and bacteria. Inflammasomes, multimeric cytosolic sensors of infection, are required for IL-1β and IL-18 processing and release. Interferons, IL-1β, and IL-18 are also implicated in autoimmune disease and chronic inflammation. Although independent but complementary pathways induce these cytokine subsets during infection, in some circumstances the cross-talk between these key inflammatory mediators is a particular requirement for effective host defense. In this review we will summarize recent discoveries concerning the potentiation of inflammasome responses by type I interferons, particularly in patients with gram-negative bacterial infections, and reflect on the molecular mechanisms of IFN-β's immunosuppressive effects through modulation of inflammasome and IL-1β signaling in patients with tuberculosis and multiple sclerosis.

Cytokine profiles show heterogeneity of interferon-β response in multiple sclerosis patients

Objective:

To evaluate serum cytokine profiles for their utility to determine the heterogeneous responses to interferon (IFN)–β treatment in patients with multiple sclerosis (MS).

Methods:

Patients with relapsing-remitting MS (RRMS) or clinically isolated syndrome receiving de novo IFN-β treatment were included in this prospective, observational study. Number of relapses and changes in disability were assessed 2 years prior to and 2 years after initiation of treatment. Sera were collected at baseline and after 3 months on therapy. Cytokine levels in sera were assessed by Luminex multiplex assays. Baseline cytokine profiles were grouped by hierarchical clustering analysis. Demographic features, changes in cytokines, and clinical outcome were then assessed in the clustered patient groups.

Results:

A total of 157 patients were included in the study and clustered into 6 distinct subsets by baseline cytokine profiles. These subsets differed significantly in their clinical and biological response to IFN-β therapy. Two subsets were associated with patients who responded poorly to therapy. Two other subsets, associated with a good response to therapy, showed a significant reduction in relapse rates and no worsening of disability. Each subset also had differential changes in cytokine levels after 3 months of IFN-β treatment.

Conclusions:

There is heterogeneity in the immunologic pathways of the RRMS population, which correlates with IFN-β response.

NLRP3 inflammasome and its inhibitors: a review

Inflammasomes are newly recognized, vital players in innate immunity. The best characterized is the NLRP3 inflammasome, so-called because the NLRP3 protein in the complex belongs to the family of nucleotide-binding and oligomerization domain-like receptors (NLRs) and is also known as “pyrin domain-containing protein 3”. The NLRP3 inflammasome is associated with onset and progression of various diseases, including metabolic disorders, multiple sclerosis, inflammatory bowel disease, cryopyrin-associated periodic fever syndrome, as well as other auto-immune and auto-inflammatory diseases. Several NLRP3 inflammasome inhibitors have been described, some of which show promise in the clinic. The present review will describe the structure and mechanisms of activation of the NLRP3 inflammasome, its association with various auto-immune and auto-inflammatory diseases, and the state of research into NLRP3 inflammasome inhibitors.

Mucosal-Associated Invariant T Cells in Multiple Sclerosis: The Jury is Still Out

The immune system is strongly implicated in the pathophysiology of multiple sclerosis (MS), as demonstrated by the efficacy of therapies targeting various components of adaptive immunity. However, the disease still progresses despite these treatments in many patients, while others experience life-threatening adverse effects, urging for the discovery of new immune-targeting medications. Among the immune cell types participating to MS pathogenesis, decades of work have highlighted the prominent role of CD4 T cells. More recent data demonstrate the involvement of CD8 T cells as well. The existence of both pathogenic and protective CD8 T cells subsets has been suggested, adding an additional layer of complexity to the picture. Mucosal-associated invariant T (MAIT) cells are innate-like lymphocytes that make up to 25% of CD8 T cells in healthy subjects. They are specific for conserved microbial ligands and may constitute an important barrier against invasive bacterial and fungal infection. An increasing number of reports also suggest their possible involvement in chronic inflammatory diseases, including MS. MAIT cells could participate through their ability to produce IFNγ and/or IL-17, two major cytokines in the pathogenesis of several chronic inflammatory/autoimmune diseases. However, the mechanisms by which MAIT cells could be activated in these sterile conditions are not known. Furthermore, contradictory observations have been made, reporting either a protective or a pro-inflammatory behavior of MAIT cells in MS or its murine model, experimental autoimmune encephalomyelitis. In this review article, we will describe the current knowledge on MAIT cell biology in health and disease, and discuss the possible mechanisms behind their role in MS. The specific features of this new non-conventional T cell subset make it an interesting candidate as a biomarker or as the target of immune-mediated intervention.

The pathogenic role of the inflammasome in neurodegenerative diseases

The inflammasome is a large macromolecular complex that contains multiple copies of a receptor or sensor of pathogen-derived or damage-derived molecular patterns, pro-caspase-1, and an adaptor called ASC (apoptotic speck containing protein with a CARD), which results in caspase-1 maturation. Caspase-1 then mediates the release of pro-inflammatory cytokines such as IL-1β and IL-18. These cytokines play critical roles in mediating immune responses during inflammation and innate immunity. Broader studies of the inflammasome over the years have implicated their roles in the pathogenesis of a variety of inflammatory diseases. Recently, studies have shown that the inflammasome modulates neuroinflammatory cells and the initial stages of neuroinflammation. A secondary cascade of events associated with neuroinflammation (such as oxidative stress) has been shown to activate the inflammasome, making the inflammasome a promising therapeutic target in the modulation of neurodegenerative diseases. This review will focus on the pathogenic role that inflammasomes play in neurologic diseases such as Alzheimer's disease, traumatic brain injury, and multiple sclerosis. We here review the role of the inflammasome in the pathogenesis of traumatic brain injury (TBI). TBI is initiated by physical force exerted to head, resulting in neuronal injury and death. Primary insult is followed by a secondary cascade of events following neuroinflammation such as mitochondrial dysfunction, production of reactive oxygen species, potassium effluxes, and release of circulating DNA. These events can potentially trigger the activation of NLRP3, NLRP1, and AIM2 during TBI but have yet to be confirmed (dashed lines). NLRP3, NLRP1, and AIM2 associate with the adaptor protein ASC, which initiates the cleavage of pro-caspase-1 to the mature form of caspase-1 which cleaves pro-IL-1β and pro-IL-18 into their mature forms of IL-1β and IL-18.