Participation of interleukin 17A in neuroimmune interactions

Neurogenic inflammation and itch in barrier tissues

Once regarded as distinct systems, the nervous system and the immune system are now recognized for their complex interactions within the barrier tissues. The neuroimmune circuitry comprises a dual-network system that detects external and internal disturbances, providing critical information to tailor a context-specific response to various threats to tissue integrity, such as wounding or exposure to noxious and harmful stimuli like pathogens, toxins, or allergens. Using the skin as an example of a barrier tissue with the polarized sensory neuronal responses of itch and pain, we explore the molecular pathways driving neuronal activation and the effects of this activation on the immune response. We then apply these findings to other barrier tissues, to find common pathways controlling neuroimmune responses in the barriers.

The immune regulatory mechanism of ketamine-induced psychiatric disorders: A new perspective on drug-induced psychiatric symptoms

Ketamine, a psychoactive substance strictly regulated by international drug conventions, is classified as a "new type drug" due to its excitatory, hallucinogenic, or inhibitory effects. The etiology of ketamine-induced psychiatric symptoms is multifaceted, with the immune regulatory mechanism being the most prominent among several explanatory theories. In recent years, the interaction between the immune system and nervous system have garnered significant attention in neuropsychiatric disorder research. Notably, the infiltration of peripheral lymphocytes into the central nervous system has emerged as an early hallmark of certain neuropsychiatric disorders. However, a notable gap exists in the current literature, regarding the immune regulatory mechanisms, specifically the peripheral immune alterations, associated with ketamine-induced psychiatric symptoms. To address this void, this article endeavors to provide a comprehensive overview of the pathophysiological processes implicated in psychiatric disorders or symptoms, encompassing those elicited by ketamine. This analysis delves into aspects such as nerve damage, alterations within the central immune system, and the regulation of the peripheral immune system. By emphasizing the intricate crosstalk between the peripheral immune system and the central nervous system, this study sheds light on their collaborative role in the onset and progression of psychiatric diseases or symptoms. This insight offers fresh perspectives on the underlying mechanisms, diagnosis and therapeutic strategies for mental disorders stemming from drug abuse.

Secukinumab Reduces Psoriasis-associated Pruritus and Regenerates the Cutaneous Nerve Architecture: Results from PSORITUS a Doubleblind, Placebo-controlled, Randomized Withdrawal Phase IIIb Study

The occurrence of pruritus in psoriasis was previously underestimated but is a significant burden. Secukinumab (SEC), a monoclonal anti-interleukin-17A antibody, efficiently controls signs of psoriasis, but the effect on pruritus and cutaneous neuroanatomy remained unknown. The primary objective of this study (NCT02362789) was to evaluate the superiority of SEC treatment vs placebo on pruritus intensity (visual analogue scale; VAS). Furthermore, the treatment-dependent course of pruritus in association with absolute Psoriasis Area Severity Index (PASI) score, as well as cutaneous histopathology and neuroanatomy, was assessed. Open-label SEC 300 mg s.c. was administered regularly until week 16. Patients who reached a ≥ 98% PASI reduction (PASI ≥ 98) were randomized to receive either placebo or SEC up to week 32. Punch biopsies were collected from lesional psoriatic (baseline, weeks 16 and 32) and non-lesional (baseline) skin for histopathological and neuroanatomical analyses. VAS scores improved significantly after open-label SEC treatment but relapsed upon placebo (29.92 ± 33.8) compared with SEC (12.30 ± 22.6; p = 0.036). After SEC-dependent improvement in PASI, histopathology, marker expression and neuroanatomy, relapse was observed with treatment discontinuation in all parameters except neuroanatomy. SEC was superior to placebo by efficiently controlling reduced pruritus intensity, clinically normalizing skin lesions, and reversing histopathological abnormalities. The neuroanatomy recovered upon SEC and remained stable even after withdrawal.

Predicting Factors and Clinical Characteristics of Pruritus in Psoriasis: A Cross-Sectional Survey

Pruritus is an important symptom among patients affected by psoriasis. To date, no general agreement has been established regarding pruritus as a measure of psoriasis severity. This study aims to assess psoriatic pruritis prevalence and characteristics using a comprehensive itch questionnaire. A semi-structured questionnaire consisting of 48 questions was applied to patients diagnosed with psoriasis and admitted to the Dermatology Department of Mures Clinical County Hospital, Romania. A total of 163 patients were enrolled, out of which 115 (70.55%) reported itch. Patients with itch had higher PASI (p = 0.003) and DLQI scores (p < 0.001). The itch was most frequently described as a crawling sensation, mainly located in the lesional skin and aggravated by stress and temperature variation. It had a moderate intensity (6.18 ± 2.46). Emollients were the treatment preferred by most patients in alleviating itch, while biologics exerted a protective effect on itch development (OR = -0.24; p < 0.0001) and negatively correlated with itch intensity (r = -0.23; p < 0.0001). Advanced age, high BMI, and PASI scores were indicators of itch presence, while female gender, high PASI score, and frequent itch episodes indicate highly intense pruritus (≥7 on the VAS). A better understanding of itch and its clinical features will guide physicians toward the best treatment option and would, ultimately, benefit the patient.

Inhibitory Effect of Evodiamine on Psoriasis Lesions and Itching in Mice

Purpose

This study seeks to investigate the effect of evodiamine on psoriasis and psoriatic pruritus.

Methods

Imiquimod-induced psoriasiform dermatitis in mice was used as a model, and evodiamine was topically applied for seven days. The mice were observed daily for skin damage on the back, clinical score and their scratching behavior was recorded. Blood samples were collected on the final day of the experiment, and the serum levels of pruritus-associated inflammatory cytokines tumor necrosis factor (TNF) -α, interleukin (IL) -23, and IL-17A were measured using enzyme-linked immunosorbent assay. Histopathological changes were observed in Hematoxylin and Eosin-stained skin specimens. The expression levels of transient receptor potential vanilloid (TRPV) 1, TRPV3, TRPV4, and the pruritus-related mediators Substance P (SP), nerve growth factor (NGF), and calcitonin gene-related peptide (CGRP) in the skin lesions were analyzed using Western blot and qRT-PCR. The effect of evodiamine on the exploratory behavior, motor, and coordination abilities of mice was assessed using open field, suspension, and Rota-Rod experiments. Molecular docking was utilized to verify the binding of evodiamine to the residues of TRPV1, TRPV3, and TRPV4.

Results

Evodiamine reduced pruritus and inhibited inflammation by decreasing the levels of inflammatory mediators TNF-α, IL-23, and IL-17A in the serum of Imiquimod-induced mice and attenuated the mRNA and protein expression levels of SP, NGF, CGRP, TRPV1, TRPV3, and TRPV4 in the skin.

Conclusion

Evodiamine is an effective treatment for psoriasis and pruritus, due to its ability to inhibit immune inflammation and pruritic mediators.

A mouse model of chronic primary pain that integrates clinically relevant genetic vulnerability, stress, and minor injury

Chronic primary pain conditions (CPPCs) affect over 100 million Americans, predominantly women. They remain ineffectively treated, in large part because of a lack of valid animal models with translational relevance. Here, we characterized a CPPC mouse model that integrated clinically relevant genetic (catechol-O-methyltransferase; COMT knockdown) and environmental (stress and injury) factors. Compared with wild-type mice, Comt+/- mice undergoing repeated swim stress and molar extraction surgery intervention exhibited pronounced multisite body pain and depressive-like behavior lasting >3 months. Comt+/- mice undergoing the intervention also exhibited enhanced activity of primary afferent nociceptors innervating hindpaw and low back sites and increased plasma concentrations of norepinephrine and pro-inflammatory cytokines interleukin-6 (IL-6) and IL-17A. The pain and depressive-like behavior were of greater magnitude and longer duration (≥12 months) in females versus males. Furthermore, increases in anxiety-like behavior and IL-6 were female-specific. The effect of COMT genotype × stress interactions on pain, IL-6, and IL-17A was validated in a cohort of 549 patients with CPPCs, demonstrating clinical relevance. Last, we assessed the predictive validity of the model for analgesic screening and found that it successfully predicted the lack of efficacy of minocycline and the CB2 agonist GW842166X, which were effective in spared nerve injury and complete Freund's adjuvant models, respectively, but failed in clinical trials. Yet, pain in the CPPC model was alleviated by the beta-3 adrenergic antagonist SR59230A. Thus, the CPPC mouse model reliably recapitulates clinically and biologically relevant features of CPPCs and may be implemented to test underlying mechanisms and find new therapeutics.

The Influence of Myeloid-Derived Suppressor Cell Expansion in Neuroinflammation and Neurodegenerative Diseases

The neuro-immune axis has a crucial function both during physiological and pathological conditions. Among the immune cells, myeloid-derived suppressor cells (MDSCs) exert a pivotal role in regulating the immune response in many pathological conditions, influencing neuroinflammation and neurodegenerative disease progression. In chronic neuroinflammation, MDSCs could lead to exacerbation of the inflammatory state and eventually participate in the impairment of cognitive functions. To have a complete overview of the role of MDSCs in neurodegenerative diseases, research on PubMed for articles using a combination of terms made with Boolean operators was performed. According to the search strategy, 80 papers were retrieved. Among these, 44 papers met the eligibility criteria. The two subtypes of MDSCs, monocytic and polymorphonuclear MDSCs, behave differently in these diseases. The initial MDSC proliferation is fundamental for attenuating inflammation in Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS), but not in amyotrophic lateral sclerosis (ALS), where MDSC expansion leads to exacerbation of the disease. Moreover, the accumulation of MDSC subtypes in distinct organs changes during the disease. The proliferation of MDSC subtypes occurs at different disease stages and can influence the progression of each neurodegenerative disorder differently.

Rapid Improvements in Itch with Tapinarof Cream 1% Once Daily in Two Phase 3 Trials in Adults with Mild to Severe Plaque Psoriasis

INTRODUCTION

Patients with psoriasis report pruritus as their most bothersome symptom. Tapinarof cream 1% once daily demonstrated significant efficacy versus vehicle and was well tolerated in adults with mild to severe plaque psoriasis in two 12-week trials: PSOARING 1 (NCT03956355) and PSOARING 2 (NCT03983980). Here, we present patient-reported pruritus outcomes from these trials.

METHODS

Outcomes included a Peak Pruritus Numerical Rating Scale (PP-NRS) score of 0 or 1 (itch-free state); Dermatology Life Quality Index (DLQI) itch item scores; and Psoriasis Symptom Diary (PSD) itch item scores.

RESULTS

Analyses included 683 tapinarof- and 342 vehicle-treated patients. At baseline, mean pruritus scores were similar across trials with only 7-11% of patients reporting an itch-free state. At week 12, the proportion of tapinarof-treated patients achieving an itch-free state was 50% in both trials compared with 32% (P = 0.0007) and 27% (P < 0.0001) in the vehicle groups. Improvements were apparent at the earliest assessments with continued improvement over the course of the trials. There were rapid and statistically significant improvements in the proportion of patients with a ≥ 4-point improvement in PP-NRS for tapinarof-treated patients versus vehicle from week 2 with 68% vs 46% (P = 0.0004) and 60% vs 31% (P = 0.0001) at week 12 achieving a response in each trial. Significantly greater reductions in itch with tapinarof versus vehicle were also demonstrated at week 12 for DLQI itch item 1 (P = 0.0026 and P < 0.0001), PSD item 1 (both P < 0.0001), and PSD item 2 (both P < 0.0001).

CONCLUSION

Tapinarof was highly efficacious in reducing pruritus across multiple patient-reported outcome measures, with rapid, statistically significant, and clinically meaningful improvements. The high proportion of patients achieving the treatment target of an itch-free state at week 12 (50%) is a noteworthy clinical outcome for a non-steroidal topical cream in the treatment of mild to severe plaque psoriasis.

TRIAL REGISTRATION

Clinical trial registration information: NCT03956355, NCT03983980.

Molecular pathways underlying lung-brain axis signaling in asthma: Relevance for psychopathology and neuroinflammation

BACKGROUND

Accumulating evidence indicates that asthma has systemic effects and affects brain function. Although airway inflammation is proposed to initiate afferent communications with the brain, the signaling pathways have not been established.

OBJECTIVE

We sought to identify the cellular and molecular pathways involved in afferent lung-brain communication during airway inflammation in asthma.

METHODS

In 23 adults with mild asthma, segmental bronchial provocation with allergen (SBP-Ag) was used to provoke airway inflammation and retrieve bronchoalveolar lavage fluid for targeted protein analysis and RNA sequencing to determine gene expression profiles. Neural responses to emotional cues in nodes of the salience network were assessed with functional magnetic resonance imaging at baseline and 48 hours after SBP-Ag.

RESULTS

Cell deconvolution and gene coexpression network analysis identified 11 cell-associated gene modules that changed in response to SBP-Ag. SBP-Ag increased bronchoalveolar lavage eosinophils and expression of an eosinophil-associated module enriched for genes related to TH17-type inflammation (eg, IL17A), as well as cell proliferation in lung and brain (eg, NOTCH1, VEGFA, and LIF). Increased expression of genes in this module, as well as several TH17-type inflammation-related proteins, was associated with an increase from baseline in salience network reactivity.

CONCLUSIONS

Our results identify a specific inflammatory pathway linking asthma-related airway inflammation and emotion-related neural function. Systemically, TH17-type inflammation has been implicated in both depression and neuroinflammation, with impacts on long-term brain health. Thus, our data emphasize that inflammation in the lung in asthma may have profound effects outside of the lung that may be targetable with novel therapeutic approaches.

Glucose transporter 1 deficiency, AMP-activated protein kinase activation and immune dysregulation in autism spectrum disorder: Novel biomarker sources for clinical diagnosis

The neurophysiological basis of autism spectrum disorder (ASD) is still uncertain. Nevertheless, studies support the hypotheses that oxidative stress, neuroinflammation, immune dysregulation, and metabolic stress are contributors. In this study, the serum levels of 3-nitrotyrosine (3-NT), hypoxia-inducible factor 1 α (HIF-1 α), heat shock protein 70 (HSP-70), interleukin-17A (IL-17A), IL-35, vitamin D3 (VITD), glucose transporter-1 (GUT1), and AMP-activated protein kinase (AMPK) were estimated in Saudi ASD children versus age-matched neurotypical controls, aiming to investigate whether these parameters have potential roles in the pathophysiologic mechanisms of ASD and hoping to find a reliable marker for early ASD diagnosis. This study included 25 ASD children and 25 typically developing children (3-11 years old). The diagnosis of ASD cases was made based on the Autism Diagnostic Observation Schedule (ADOS) and the Statistical Manual of Mental Disorders (DSM-5). ASD subjects were commonly male and revealed an intelligence quotient (IQ) < 70.The results detected that ASD children have remarkable greater serum levels of nitrosative stress (3-NT), hypoxia (HIF-1 α), inflammatory (HSP-70, IL-17A, and AMPK) biomarkers and lower serum levels of anti-inflammatory (IL-35 and VITD) and metabolic stress (GUT-1) biomarkers versus age-matched controls (P ≤ 0.0001). Pearson's correlation study revealed that 3-NT was positively associated with HIF-1 α and HSP-70. HIF-1 α was also positively correlated with HSP-70. AMPK was positively associated with GUT-1, however, IL-17A was negatively correlated with IL-35 and VITD.Limitation:No specific therapeuticdrugs were administered in this study, and further studies are required to confirm the role of the selected biomarkers in ASD managements.

Conclusion

Changes in concentrations of different biomarkers indicate that they are involved in oxidative stress, metabolic stress, immune dysregulation and ASD pathogenesis. Hence, these parameters can prove to be promising biomarkers as well as therapeutic targets for the timely diagnosis and treatment of ASD patients.

Advances in the study of IL-17 in neurological diseases and mental disorders

Interleukin-17 (IL-17), a cytokine characteristically secreted by T helper 17 (Th17) cells, has attracted increasing attention in recent years because of its importance in the pathogenesis of many autoimmune or chronic inflammatory diseases. Recent studies have shown that neurological diseases and mental disorders are closely related to immune function, and varying degrees of immune dysregulation may disrupt normal expression of immune molecules at critical stages of neural development. Starting from relevant mechanisms affecting immune regulation, this article reviews the research progress of IL-17 in a selected group of neurological diseases and mental disorders (autism spectrum disorder, Alzheimer's disease, epilepsy, and depression) from the perspective of neuroinflammation and the microbiota-gut-brain axis, summarizes the commonalities, and provides a prospective outlook of target application in disease treatment.

Association of granulocyte macrophage colony-stimulating factor and interleukin-17 levels with obsessive-compulsive disorder: a case-control study findings

Obsessive-compulsive disorder (OCD) is a mental condition that affects many people and is characterized by recurring obsessions and compulsions. It significantly impacts individuals' ability to function ordinarily daily, affecting people of all ages. This study aimed to investigate whether or not the cytokines granulocyte macrophage colony-stimulating factor (GM-CSF) and interleukin-17 (IL-17) are involved in the pathophysiology of OCD. A case-control study with 50 OCD patients and 38 healthy volunteers served as the controls for this investigation. The levels of GM-CSF and IL-17 in the serum of both groups were measured with enzyme-linked immunosorbent assay (ELISA) kits. In addition, the sociodemographic characteristics of the population under study were studied. Based on the findings of this study, OCD patients had significantly elevated levels of IL-17 than the controls, it appears that there may be a function for IL-17 in the pathophysiology of OCD. It was also discovered that the severity of OCD and IL-17 levels had a significant positive correlation. On the other hand, when comparing the levels of GM-CSF, there was no significant difference between the patients and the controls. This study provides evidence supporting the involvement of cytokine IL-17 in the pathophysiology of OCD. This study suggests IL-17 as a diagnostic biomarker for OCD and adds to our knowledge of the function that the immune system plays in this condition.

[Translated article] Pruritus in Dermatology: Part 2-Diseases and Their Treatment

Pruritus is the main symptom of many dermatologic and systemic diseases. Atopic dermatitis, psoriasis, contact dermatitis, urticaria, lichen simplex chronicus, mycosis fungoides, scars, autoimmune diseases, kidney or liver diseases among others are all associated with itch that may require different approaches to management. Although antihistamines seem to be the first line of therapy, in reality their role is limited to urticaria and drug-induced reactions. In fact, the pathophysiologic mechanisms of each of the conditions covered in this review will differ. Recent years have seen the emergence of new drugs whose efficacy and safety profiles are very attractive for the management of pruritus in clinical practice. Clearly, we are at a critical moment in dermatology, in which we have the chance to be more ambitious in our goals when treating patients with pruritus.

The Role of BDNF in Multiple Sclerosis Neuroinflammation

Multiple sclerosis (MS) is a chronic, inflammatory, and degenerative disease of the central nervous system (CNS). Inflammation is observed in all stages of MS, both within and around the lesions, and can have beneficial and detrimental effects on MS pathogenesis. A possible mechanism for the neuroprotective effect in MS involves the release of brain-derived neurotrophic factor (BDNF) by immune cells in peripheral blood and inflammatory lesions, as well as by microglia and astrocytes within the CNS. BDNF is a neurotrophic factor that plays a key role in neuroplasticity and neuronal survival. This review aims to analyze the current understanding of the role that inflammation plays in MS, including the factors that contribute to both beneficial and detrimental effects. Additionally, it explores the potential role of BDNF in MS, as it may modulate neuroinflammation and provide neuroprotection. By obtaining a deeper understanding of the intricate relationship between inflammation and BDNF, new therapeutic strategies for MS may be developed.

Activation of the IL-17/TRAF6/NF-κB pathway is implicated in Aβ-induced neurotoxicity

BACKGROUND

Neuroinflammation plays a critical role in Amyloid-β (Aβ) pathophysiology. The cytokine, interleukin-17A (IL-17) is involved in the learning and memory process in the central nervous system and its level was reported to be increased in Alzheimer's disease (AD) brain, while the effect of IL-17 on the course of Aβ has not been well defined.

METHODS

Here, we used APP/PS1 mice to detect the IL-17 expression level. Primary hippocampal neurons were treated with IL-17, and immunofluorescence was used to investigate whether IL-17 induced neuron damage. At the same time, male C57BL/6 mice were injected with Aβ42 to mimic the Aβ model. Then IL-17 neutralizing antibody (IL-17Ab) was used to inject into the lateral ventricle, and the Open field test, Novel Objective Recognition test, Fear condition test were used to detect cognitive function. LTP was used to assess synaptic plasticity, molecular biology technology was used to assess the IL-17/TRAF6/NF-κB pathway, and ELISA was used to detect inflammatory factors.

RESULTS

Altogether, we here found that IL-17 was increased in APP/PS1 mice, and it induced neural damage by the administration to primary hippocampal neurons. Interestingly, Using Aβ42 mice, the results showed that the level of IL-17 was increased in Aβ42 model mice, and IL-17Ab could ameliorate Aβ-induced neurotoxicity and cognitive decline in C57BL/6 mice by downregulation the TRAF6/NF-κB pathway.

CONCLUSION

These findings highlight the pathogenic role of IL-17 in Aβ induced-synaptic dysfunction and cognitive deficits. Inhibition of IL-17 could ameliorate Aβ-induced neurotoxicity and cognitive decline in C57BL/6 mice by downregulation of the TRAF6/NF-κB pathway, which provides new clues for the mechanism of Aβ-induced cognitive impairments, and a basis for therapeutic intervention.

Electrical, structural, and autonomic atrial remodeling underlies atrial fibrillation in inflammatory atrial cardiomyopathy

Background

There is growing evidence indicating a close relationship between inflammation and atrial fibrillation (AF). Although underlying inflammatory atrial cardiomyopathy may contribute to the development of AF, the arrhythmogenic remodeling caused by atrial inflammation has not been elucidated in detail. Herein, we examined electrical, structural, and autonomic changes in the atria in a mouse model of autoimmune myocarditis.

Methods

BALB/c mice were immunized with cardiac myosin peptide (MyHC-α_614-629) conjugated with complete Freund's adjuvant on days 0 and 7. Susceptibility to AF was assessed using right-atrial burst pacing.

Results

The mice immunized with MyHC-α_614-629 showed an inflammatory atrial cardiomyopathy phenotype, with enlarged atria; a high degree of inflammatory cell infiltration primarily consisting of CD4⁺ T cells, CD8⁺ T cells, Ly6G^lowCD11b⁺ macrophages, and CD11c⁺ dendritic cells; and severe interstitial fibrosis with collagen deposition. These mice demonstrated significantly enhanced susceptibility to AF, as indicated by their increased AF induction rate and duration. In addition, the expression of potassium channels (Kcnh2, Kcnd3, and Kcnj2) and calcium handling-associated genes (Cacna1c, Camk2, Ryr2, and Atp2a2) was downregulated. Connexin 40 expression was significantly downregulated, leading to frequent lateralization to the inflamed atrium. Sympathetic and parasympathetic innervation and neurotrophin expression (nerve growth factor and brain-derived neurotrophic factor) were upregulated in the inflamed atria.

Conclusion

Inflammatory atrial cardiomyopathy promotes susceptibility to AF via arrhythmogenic electrical, structural, and autonomic remodeling of the atria.

Therapeutic anti-amyloid β antibodies cause neuronal disturbances

INTRODUCTION

Recent published clinical trial safety data showed that 41% of Alzheimer patients experienced amyloid-related imaging abnormalities (ARIA), marks of microhemorrhages and edema in the brain, following administration of Biogen's Aduhelm/aducanumab (amino acids 3-7 of the Aβ peptide). Similarly, Janssen/Pfizer's Bapineuzumab (amino acids 1-5 of the Aβ peptide) and Roche's Gantenerumab (amino acids 2-11/18-27 of the Aβ peptide) also displayed ARIA in clinical trials, including microhemorrhage and focal areas of inflammation or vasogenic edema, respectively. The molecular mechanisms underlying ARIA caused by therapeutic anti-Aβ antibodies remain largely unknown, however, recent reports demonstrated that therapeutic anti-prion antibodies activate neuronal allergenic proteomes following cross-linking cellular prion protein.

METHODS

Here, we report that treatment of human induced pluripotent stem cells- derived neurons (HSCN) from a non-demented donor, co-cultured with human primary microglia with anti-Aβ1-6, or anti-Aβ17-23 antibodies activate a significant number of allergenic-related proteins as assessed by mass spectrometry.

RESULTS

Interestingly, a large proportion of the identified proteins included cytokines such as interleukin (IL)-4, IL-12, and IL-13 suggesting a type-1 hypersensitivity response. Following flow cytometry analysis, several proinflammatory cytokines were significantly elevated following anti-Aβ1-6, or anti-Aβ17-23 antibody treatment.

DISCUSSION

These results justify further and more robust investigation of the molecular mechanisms of ARIA during immunotherapy study trials of AD.

HIGHLIGHTS

Allergenic-related proteins are often linked with Alzheimer's disease (AD). We investigated the effects of amyloid beta (Aβ) immunotherapy on stem cell derived neurons and primary neuronal cells co-cultured with microglia. Anti-Aβ antibody treatment of neurons or neurons co-cultured with microglia led to activation of a substantial number of allergenic-related genes. These allergenic-related genes are associated with endothelial dysfunction possibly responsible for ARIA.

Interleukin-17 as a potential therapeutic target for chronic pain

Chronic pain remains to be a clinical challenge and is recognized as a major health problem with varying impacts on quality of life. Currently, the first-line therapy for chronic pain is opioids, which are often accompanied by unwanted psychoactive side effects. Thus, new and effective treatments for chronic pain are urgently needed and eagerly pursued. Inflammatory cytokines, especially interleukin-17 (IL-17), are reportedly potential therapeutic targets owing to their pivotal role in chronic pain from the neuroinflammation perspective. Recently, substantial evidence confirmed that IL-17 and IL-17 receptors (IL-17Rs) were increased in neuropathic, inflammatory, and cancer pain models. Notably, IL-17/IL-17R antibodies also reportedly relieve or cure inflammatory- and pain-related diseases. However, existing studies have reported controversial results regarding IL-17/IL-17Rs as potential therapeutic targets in diverse animal models of chronic pain. In this review, we present a summary of published studies and discuss the evidence, from basic to clinical to research, regarding the role and mechanism of action between IL-17 and diverse kinds of chronic pain in animal models and clinical patients. Furthermore, we evaluated IL-17-based therapy as a potential therapeutic strategy for inflammatory- and pain-related disease. Importantly, we also discussed clinical trials of IL-17/IL-17R targeting monoclonal antibodies. Overall, we found that IL-17 is a potential therapeutic target for chronic pain from the perspective of neuroinflammation.

Neuroinflammation and Proinflammatory Cytokines in Epileptogenesis

Increasing evidence corroborates the fundamental role of neuroinflammation in the development of epilepsy. Proinflammatory cytokines (PICs) are crucial contributors to the inflammatory reactions in the brain. It is evidenced that epileptic seizures are associated with elevated levels of PICs, particularly interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α), which underscores the impact of neuroinflammation and PICs on hyperexcitability of the brain and epileptogenesis. Since the pathophysiology of epilepsy is unknown, determining the possible roles of PICs in epileptogenesis could facilitate unraveling the pathophysiology of epilepsy. About one-third of epileptic patients are drug-resistant, and existing treatments only resolve symptoms and do not inhibit epileptogenesis; thus, treatment of epilepsy is still challenging. Accordingly, understanding the function of PICs in epilepsy could provide us with promising targets for the treatment of epilepsy, especially drug-resistant type. In this review, we outline the role of neuroinflammation and its primary mediators, including IL-1β, IL-1α, IL-6, IL-17, IL-18, TNF-α, and interferon-γ (IFN-γ) in the pathophysiology of epilepsy. Furthermore, we discuss the potential therapeutic targeting of PICs and cytokine receptors in the treatment of epilepsy.

The Microbiota-Gut-Brain Axis and Epilepsy

Honoured as the second genome in humans, the gut microbiota is involved in a constellation of physiological and pathological processes, including those related to the central nervous system. The communication between the gut microbiota and the brain is realized by a complex bidirectional connection, known as the "microbiota-gut-brain axis", via neuroendocrine, immunological, and direct neural mechanisms. Recent studies indicate that gut dysfunction/dysbiosis is presumably involved in the pathogenesis of and susceptibility to epilepsy. In addition, the reconstruction of the intestinal microbiome through, for example, faecal microbiota transplantation, probiotic intervention, and a ketogenic diet, has exhibited beneficial effects on drug-resistant epilepsy. The purposes of this review are to provide a brief overview of the microbiota-gut-brain axis and to synthesize what is known about the involvement of the gut microbiota in the pathogenesis and treatment of epilepsy, to bring new insight into the pathophysiology of epilepsy and to present a preliminary discussion of novel therapeutic options for epilepsy based on the gut microbiota.

LOWER ANTIDEPRESSANT RESPONSE TO FLUOXETINE IS ASSOCIATED WITH ANXIETY-LIKE BEHAVIOR, HIPPOCAMPAL OXIDATIVE IMBALANCE, AND INCREASE ON PERIPHERAL IL-17 AND IFN-γ LEVELS

Major depression is a leading contributor to the global burden of disease. This is mainly related to the disorder chronic and recurrent nature, and to high rates of refractoriness to treatment. Limited efficacy with currently available antidepressants highlights the need for more effective options for treating drug-resistant patients and emphasizes the importance of developing specific preclinical models for treatment-resistant populations. Treatment-resistant depression (TRD) is commonly defined as failure to respond to two or more trials of antidepressants. In this study, we investigated the effect of fluoxetine treatment for fourteen days on the depressive-like behavior and the oxidative and inflammatory parameters of mice submitted to chronic corticosterone administration. After 21 days of subcutaneous corticosterone administration (20mg/Kg/day) and 14 days of oral fluoxetine treatment (10mg/Kg/day, started on day 7 of induction protocol), we separated animals into two groups according to the tail suspension test's (TST) results: antidepressant responders (good response to antidepressant, GRA) and non-responders (resistance to antidepressant, AR). Forced swimming test (FST), elevated plus maze test (EPMT), and open field test (OFT) were performed. We found that animals classified as AR (i.e., those with higher immobility values in the TST) demonstrated anxiety-like behavior in the EPMT, increased H₂O₂ levels, and decreased catalase activity in the hippocampus, as well as increased serum levels of IL-17 and IFN-γ. Our findings suggest that a redox imbalance in the hippocampus, combined with increased levels of peripheral IL-17 and INF-γ, may be involved with an impaired response to fluoxetine.

Th17 cell-mediated immune response in a subpopulation of dogs with idiopathic epilepsy

BACKGROUND

Canine idiopathic epilepsy (IE) is a common neurological disease with severe impact on the owner´s and the dog's quality of life. A subpopulation of dogs with IE does not respond to antiseizure drugs (non-responder). Th17 cells (T helper cells) and their proinflammatory Interleukin-17 (IL-17) are part of the immune system and previous studies showed their involvement in the pathogenesis of several autoimmune diseases. Non-responder might have an abnormal immune response against structures of the central nervous system. To discover a new aetiology of canine IE and thereby optimising the therapy of intractable IE, this prospective study aimed to investigate Th17 cells and IL-17 in dogs with IE. The underlying hypothesis was that in some dogs with IE a Th17 cell-mediated immune response could be detectable.

METHODS

57 dogs with IE and 10 healthy dogs (control group, C) were enrolled in the study. EDTA blood was taken to measure Th17 cells by flow cytometry. IL-17 was measured in 35 cerebrospinal fluid (CSF) and 33 serum samples using an enzyme-linked immunosorbent assay (ELISA). It was investigated whether there was a significant increase of stimulated Th17 cells in blood samples or of IL-17 in serum and CSF samples of dogs with IE in comparison to C. Correlations between the amount of Th17 cells/μL or IL-17 and different clinical parameters e.g. seizure frequency, seizure type, seizure severity or treatment response were evaluated. Additionally, Th17 cells/μL were randomly controlled of 17 dogs with IE and were examined for changes over time and in relation to treatment response.

RESULTS

Ten dogs with IE had strongly elevated stimulated Th17 cells/μL within the blood (>100 Th17 cells/μL). A slight positive correlation between stimulated Th17 cells/μL and seizure severity (p = 0.046; rSpear = 0.27) was proven in these dogs. In addition, 4/10 dogs with elevated Th17 levels experienced cluster seizures and status epilepticus in comparison to 9% of the dogs with non-elevated Th17 levels (<100 Th17 cells/μL). Dogs with IE had significantly higher IL-17 values in CSF and serum samples compared to C (p<0.001; p<0.002; respectively).

CONCLUSION

In single dogs with IE, strongly increased amounts of Th17 cells were detectable and dogs with elevated Th17 cells seemed to have a greater risk for experiencing a combination of cluster seizures and status epilepticus. Therefore, an underlying Th17-cell mediated immune response was suspected and hence anti-inflammatory drugs could be indicated in these single cases with intractable epilepsy.

Interleukin-17 affects synaptic plasticity and cognition in an experimental model of multiple sclerosis

Cognitive impairment (CI) is a disabling concomitant of multiple sclerosis (MS) with a complex and controversial pathogenesis. The cytokine interleukin-17A (IL-17A) is involved in the immune pathogenesis of MS, but its possible effects on synaptic function and cognition are still largely unexplored. In this study, we show that the IL-17A receptor (IL-17RA) is highly expressed by hippocampal neurons in the CA1 area and that exposure to IL-17A dose-dependently disrupts hippocampal long-term potentiation (LTP) through the activation of its receptor and p38 mitogen-activated protein kinase (MAPK). During experimental autoimmune encephalomyelitis (EAE), IL-17A overexpression is paralleled by hippocampal LTP dysfunction. An in vivo behavioral analysis shows that visuo-spatial learning abilities are preserved when EAE is induced in mice lacking IL-17A. Overall, this study suggests a key role for the IL-17 axis in the neuro-immune cross-talk occurring in the hippocampal CA1 area and its potential involvement in synaptic dysfunction and MS-related CI.

Maximizing the Utility of Transcriptomics Data in Inflammatory Skin Diseases

Inflammatory skin diseases are induced by disorders of the host defense system of the skin, which is composed of a barrier, innate and acquired immunity, as well as the cutaneous microbiome. These disorders are characterized by recurrent cutaneous lesions and intense itch, which seriously affecting life quality of people across all ages and ethnicities. To elucidate molecular factors for typical inflammatory skin diseases (such as psoriasis and atopic dermatitis), transcriptomic profiling assays have been largely performed. Additionally, single-cell RNA sequencing (scRNA-seq) as well as spatial transcriptomic profiling have revealed multiple potential translational targets and offered guides to improve diagnosis and treatment strategies for inflammatory skin diseases. High-throughput transcriptomics data has shown unprecedented power to disclose the complex pathophysiology of inflammatory skin diseases. Here, we will summarize discoveries from transcriptomics data and discuss how to maximize the transcriptomics data to propel the development of diagnostic biomarkers and therapeutic targets in inflammatory skin diseases.

Th17 Cells in Depression: Are They Crucial for the Antidepressant Effect of Ketamine?

Background: Major depressive disorder is associated with inflammation and immune processes. Depressive symptoms correlate with inflammatory markers and alterations in the immune system including cytokine levels and immune cell function. Th17 cells are a T cell subset which exerts proinflammatory effects. Th17 cell accumulation and Th17/Treg imbalances have been reported to be critical in the pathophysiology of major depressive disorder and depressive-like behaviors in animal models. Th17 cells are thought to interfere with glutamate signaling, dopamine production, and other immune processes. Ketamine is a newly characterized antidepressant medication which has proved to be effective in rapidly reducing depressive symptoms. However, the mechanisms behind these antidepressant effects have not been fully elucidated.

Method: Literature about Th17 cells and their role in depression and the antidepressant effect of ketamine are reviewed, with the possible interaction networks discussed.

Result: The immune-modulating role of Th17 cells may participate in the antidepressant effect of ketamine.

Conclusion: As Th17 cells play multiple roles in depression, it is important to explore the mechanisms of action of ketamine on Th17 cells and Th17/Treg cell balance. This provides new perspectives for strengthening the antidepressant effect of ketamine while reducing its side effects and adverse reactions.

Pruritus in psoriasis and atopic dermatitis: current treatments and new perspectives

Psoriasis and atopic dermatitis (AD) are two common chronic inflammatory skin diseases. Although showing different etiology and clinical manifestations, patients with either disease suffer from low health-related quality of life due to pruritus (dermal itch). Recent studies have revealed that more than 85% of psoriasis patients suffer from pruritus, and it is also the dominating symptom of AD. However, as this is a non-life treating symptom, it was partly neglected for years. In this review, we focus on current findings as well as the impact and potential treatments of pruritus in these two skin diseases. We first distinguish the type of itch based on involved mediators and modulators. This clear delineation between the types of pruritus based on involved receptors and pathways allows for precise treatment. In addition, insights into recent clinical trials aimed to alleviate pruritus by targeting these receptors are presented. We also report about novel advances in combinatorial treatments, dedicated to the type of pruritus linked to a causal disease. Altogether, we suggest that only a focused treatment tailored to the primary disease and the underlying molecular signals will provide fast and sustained relief of pruritus associated with psoriasis or AD.

The burden of depressive disorders in musculoskeletal diseases: is there an association between mood and inflammation?

IMPORTANCE

Evidence emerged concerning how inflammatory arthritis and mood disorders can often occur in the same patient and show a similar clinical pattern. An overview of the rheumatological and psychiatric aspects of these diseases can certainly be useful for the improvement of patients' clinical and therapeutic management.

OBJECTIVE

The aim of this narrative review was to summarize existing literature about common pathogenetic and clinical aspects as a means of improving management and therapeutic approach in patients affected by rheumatoid arthritis, psoriatic arthritis and spondyloarthritis. Outcomes such as disease activity indexes and patient reported outcomes (PROs) were considered.

FINDINGS

Common pathogenetic pathways emerged between inflammatory arthritis and mood disorders. Pro-inflammatory mechanisms, such as TNFα, IL-6, IL-17 and oxidative stress factors as well as neurotransmitter alterations at the level of CNS and blood-brain barrier (BBB) cells are involved. The activation of these common pathogenetic pathways is, also, affected by the same triggers, such as smoking, stress, lifestyle, and evidence has emerged concerning the possibility of the clinical efficacy of using the same therapeutic approaches.

CONCLUSIONS

The main causes of the variability in clinical studies outcomes are the rheumatological diseases considered, the prevalence of depression in the general population and in patients with rheumatological diseases and the type of depressive symptom examined. Patients affected by inflammatory arthritis can present symptoms and signs in common with mood disorders, leading to possible clinical overlap. There are still few studies analyzing this concept: they are extremely heterogeneous, both in the characteristics of the population taken into consideration and in the methods used for the definition of depressive disorder, but the suggestions of the data obtained so far are promising and deserve to be pursued.

Interaction of pain and chronic inflammation

Rheumatic diseases are characterized by chronic inflammation of synovial joints and are often associated with persistent pain and increased pain sensitivity. The inflammatory process is a complex cascade of events involving several mediators, which can lead to a chronic condition of pain. Inflammation can stimulate angiogenesis, and angiogenesis can facilitate inflammation. Inflammatory pain arises from tissue damage via the sensitization of pain receptors (nociceptors). The main peripheral mechanism underlying nociceptive pain is a change in the activity of the nociceptors located in the affected anatomical structures (joints, tendons, and ligaments), which renders them more sensitive to normally painful stimuli (hyperalgesia) or normally non-painful stimuli (allodynia). Neuroimmune interaction has been considered to play an essential role in rheumatic disease. Neurogenic inflammation, which influences normal central nervous system signaling, leads to insufficient signaling/bioavailability of various cytokines. These central mechanisms play an important role in the increased pain sensitivity following inflammation and are responsible for the development of secondary hyperalgesia in regions beyond the injured tissue. Reduction of pain in rheumatic disease requires familiarity with various pain mechanisms.

Molecular and Cellular Mechanisms of Itch in Psoriasis

Itch (or pruritus) was not previously recognized as a serious symptom of psoriasis. However, approximately 60-90% of psoriatic patients with pruritus have stated that it deteriorates their quality of life. Since conventional antipruritic therapies, such as antihistamines, only exert limited effects, the establishment of a treatment option for itch in psoriasis is urgently needed. Although a definitive drug is not currently available, various itch mediators are known to be involved in pruritus in psoriasis. In this review, we describe the clinical features of pruritus in psoriasis, classify a wide range of itch mediators into categories, such as the nervous, immune, endocrine, and vascular systems, and discuss the mechanisms by which these mediators induce or aggravate itch in the pathophysiology of psoriasis.

The neuropathic phenotype of the K/BxN transgenic mouse with spontaneous arthritis: pain, nerve sprouting and joint remodeling

The adult K/BxN transgenic mouse develops spontaneous autoimmune arthritis with joint remodeling and profound bone loss. We report that both males and females display a severe sustained tactile allodynia which is reduced by gabapentin but not the potent cyclooxygenase inhibitor ketorolac. In dorsal horn, males and females show increased GFAP⁺ astrocytic cells; however, only males demonstrate an increase in Iba1⁺ microglia. In dorsal root ganglia (DRG), there is an increase in CGRP⁺, TH⁺, and Iba1⁺ (macrophage) labeling, but no increase in ATF3⁺ cells. At the ankle there is increased CGRP⁺, TH⁺, and GAP-43⁺ fiber synovial innervation. Thus, based on the changes in dorsal horn, DRG and peripheral innervation, we suggest that the adult K/BxN transgenic arthritic mice display a neuropathic phenotype, an assertion consistent with the analgesic pharmacology seen in this animal. These results indicate the relevance of this model to our understanding of the nociceptive processing which underlies the chronic pain state that evolves secondary to persistent joint inflammation.

Characterization of the Th17 profile immune response in cases of human rabies transmitted by dogs and its interference in the disease pathogenesis

The Th17 profile immune response is influenced by the presence of cytokines such as IL-1, IL-6, TGF-β, IL-17, and IL-23. We sought to characterize the Th17 profile in CNS samples from human rabies cases transmitted by dogs and examine its possible influence on disease pathogenesis. We observed a high expression of TGF-β, followed by IL-23, IL-17 and IL-6, and a low expression of IL-1β and IFN-γ. Those results suggest the participation of Th17 in rabies virus neuroinfection transmitted by dogs. IL-23 probably plays a role in maintaining the Th17 profile, but it can also interfere with the establishment of the Th1 profile and viral clearance.

TDAG8 deficiency reduces satellite glial number and pro-inflammatory macrophage number to relieve rheumatoid arthritis disease severity and chronic pain

Background

The autoimmune disease rheumatoid arthritis (RA) affects approximately 1% of the global population. RA is characterized with chronic joint inflammation and often associated with chronic pain. The imbalance of pro-inflammatory and anti-inflammatory macrophages is a feature of RA progression. Glial cells affecting neuronal sensitivity at both peripheral and central levels may also be important for RA progression and associated pain. Genetic variants in the T cell death-associated gene 8 (TDAG8) locus are found to associate with spondyloarthritis. TDAG8 was also found involved in RA disease progression and associated hyperalgesia in the RA mouse model. However, its modulation in RA remains unclear.

Methods

To address this question, we intra-articularly injected complete Freund’s adjuvant (CFA) into TDAG8^+/+, TDAG8^−/− or wild-type mice, followed by pain behavioral tests. Joints and dorsal root ganglia were taken, sectioned, and stained with antibodies to observe the number of immune cells, macrophages, and satellite glial cells (SGCs). For compound treatments, compounds were intraperitoneally or orally administered weekly for 9 consecutive weeks after CFA injection.

Results

We demonstrated that TDAG8 deletion slightly reduced RA pain in the early phase but dramatically attenuated RA progression and pain in the chronic phase (> 7 weeks). TDAG8 deletion inhibited an increase in SGC number and inhibition of SGC function attenuated chronic phase of RA pain, so TDAG8 could regulate SGC number to control chronic pain. TDAG8 deletion also reduced M1 pro-inflammatory macrophage number at 12 weeks, contributing to the attenuation of chronic RA pain. Such results were further confirmed by using salicylanilide derivatives, CCL-2d or LCC-09, to suppress TDAG8 expression and function.

Conclusions

This study demonstrates that TDAG8 deletion reduced SGC and M1 macrophage number to relieve RA disease severity and associated chronic pain. M1 macrophages are critical for the development and maintenance of RA disease and pain, but glial activation is also required for the chronic phase of RA pain.

Plasma Erythropoietin, IL-17A, and IFNγ as Potential Biomarkers of Motor Function Recovery in a Canine Model of Spinal Cord Injury

Traumatic spinal cord injury (SCI) is a devastating neurological disease for which an accurate, cost-effective prediction of motor function recovery is in pressing need. A plethora of neurochemical changes involved in the pathophysiological process of SCI may serve as a new source of biomarkers for patient outcomes. Five dogs were included in this study. We characterized the plasma cytokine profiles in acute phase (0, 1, and 3 days after SCI) and subacute phase (7, 14, and 21 days after SCI) with microarray analysis. The motor function recovery following SCI was monitored by Olby scores. The expression level of differentially expressed proteins (DEPs) was measured with enzyme-linked immunosorbent assay (ELISA). Then, correlations with the Olby scores and receiver operating characteristic curve (ROC) analysis were performed. We identified 12 DEPs including 10 pro-inflammatory and 2 anti-inflammatory cytokines during the 21-day study period. Among those, the expression levels of erythropoietin (EPO), IL-17A, and IFNγ significantly correlated with the Olby scores with R² values of 0.870, 0.740, and 0.616, respectively. The results of the ROC analysis suggested that plasma EPO, IL-17A, and IFNγ exhibited a significant predictive power with an area under the curve (AUC) of 0.656, 0.848, and 0.800 for EPO, IL-17A, and IFNγ, respectively. Our results provide a longitudinal description of the changes in plasma cytokine expression in the acute and subacute stages of canine SCI. These data reveal novel panels of inflammation-related cytokines which have the potential to be evaluated as biomarkers for predicting motor function prognosis after SCI.

Neuraxial Cytokines in Pain States

A high-intensity potentially tissue-injuring stimulus generates a homotopic response to escape the stimulus and is associated with an affective phenotype considered to represent pain. In the face of tissue or nerve injury, the afferent encoding systems display robust changes in the input-output function, leading to an ongoing sensation reported as painful and sensitization of the nociceptors such that an enhanced pain state is reported for a given somatic or visceral stimulus. Our understanding of the mechanisms underlying this non-linear processing of nociceptive stimuli has led to our appreciation of the role played by the functional interactions of neural and immune signaling systems in pain phenotypes. In pathological states, neural systems interact with the immune system through the actions of a variety of soluble mediators, including cytokines. Cytokines are recognized as important mediators of inflammatory and neuropathic pain, supporting system sensitization and the development of a persistent pathologic pain. Cytokines can induce a facilitation of nociceptive processing at all levels of the neuraxis including supraspinal centers where nociceptive input evokes an affective component of the pain state. We review here several key proinflammatory and anti-inflammatory cytokines/chemokines and explore their underlying actions at four levels of neuronal organization: (1) peripheral nociceptor termini; (2) dorsal root ganglia; (3) spinal cord; and (4) supraspinal areas. Thus, current thinking suggests that cytokines by this action throughout the neuraxis play key roles in the induction of pain and the maintenance of the facilitated states of pain behavior generated by tissue injury/inflammation and nerve injury.

Systemic Exposure to Lipopolysaccharide from Porphyromonas gingivalis Induces Bone Loss-Correlated Alzheimer's Disease-Like Pathologies in Middle-Aged Mice

BACKGROUND

Alzheimer's disease (AD) and bone loss are clinically exacerbated. However, the mechanism of exacerbation remains understood.

OBJECTIVE

We tested our hypothesis that periodontitis is involved in the exacerbation, contributing to AD pathologies.

METHODS

The bone, memory, and inflammation in bone and brain were examined in 12-month-old mice after systemic exposure to lipopolysaccharide from Porphyromonas gingivalis (P gLPS) for 3 consecutive weeks.

RESULTS

Compared with control mice, bone loss in tibia (26% decrease) and memory decline (47% decrease) were induced in mice with a positive correlation after exposure to P gLPS (r = 0.7378, p = 0.0011). The IL-6 and IL-17 expression in tibia was negatively correlated with the bone volume/total tissue volume (r = -0.6619, p = 0.0052; r = -0.7129, p = 0.0019), while that in the cortex was negatively correlated with the memory test latency (r = -0.7198, p = 0.0017; p = 0.0351, r = -0.5291). Furthermore, the IL-17 expression in microglia was positively correlated with Aβ42 accumulation in neurons (r = 0.8635, p < 0.0001). In cultured MG6 microglia, the P gLPS-increased IL-6 expression was inhibited by a PI3K-specific inhibitor (68% decrease), and that of IL-17 was inhibited by IL-6 antibody (41% decrease). In cultured N2a neurons, conditioned medium from P gLPS-stimulated microglia (MCM) but not P gLPS increased the productions of AβPP, CatB, and Aβ42, which were significantly inhibited by pre-treatment with IL-17 antibody (67%, 51%, and 41% decrease).

CONCLUSION

These findings demonstrated that chronic systemic exposure to P gLPS simultaneously induces inflammation-dependent bone loss and AD-like pathologies by elevating IL-6 and IL-17 from middle age, suggesting that periodontal bacteria induce exacerbation of bone loss and memory decline, resulting in AD progression.

Sex differences in central nervous system plasticity and pain in experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a neurodegenerative autoimmune disease with many known structural and functional changes in the central nervous system. A well-recognized, but poorly understood, complication of MS is chronic pain. Little is known regarding the influence of sex on the development and maintenance of MS-related pain. This is important to consider, as MS is a predominantly female disease. Using the experimental autoimmune encephalomyelitis (EAE) mouse model of MS, we demonstrate sex differences in measures of spinal cord inflammation and plasticity that accompany tactile hypersensitivity. Although we observed substantial inflammatory activity in both sexes, only male EAE mice exhibit robust staining of axonal injury markers and increased dendritic arborisation in morphology of deep dorsal horn neurons. We propose that tactile hypersensitivity in female EAE mice may be more immune-driven, whereas pain in male mice with EAE may rely more heavily on neurodegenerative and plasticity-related mechanisms. Morphological and inflammatory differences in the spinal cord associated with pain early in EAE progression supports the idea of differentially regulated pain pathways between the sexes. Results from this study may indicate future sex-specific targets that are worth investigating for their functional role in pain circuitry.

Itch: an under-recognized problem in psoriasis

Psoriasis has historically been considered a nonpruritic dermatosis, in contrast with atopic dermatitis. Thus, itch has often been underappreciated and overlooked in psoriasis. However, increasing evidence over the past decade has shown that itch can be one of the most prevalent and burdensome symptoms associated with psoriasis, affecting almost every patient to some degree. Itch can involve the entire body, although it predominantly affects the legs, hands, back, body and especially the scalp. Uncontrolled itch can significantly impact all aspects of the well-being and quality of life of the patient. While there has been some progress in trying to better understand the pathophysiology of itch in psoriasis, more research effort and interest are needed. This under-recognition of itch in psoriasis is clearly reflected in the dearth of treatment options targeting itch despite significant advancement in treating the lesions themselves. Recently, however, clinical studies have begun to include itch as a study outcome. The resulting data have demonstrated concomitant antipruritic benefits and improved Psoriasis Area and Severity Index (PASI) scores with mainstay treatments for psoriasis, such as topical corticosteroids and vitamin D analogs, phototherapies, and various systemics and biologics. This article takes a closer look at this debilitating symptom, reviewing the available epidemiology data for psoriatic itch, presenting the current understanding of psoriatic itch pathophysiology and highlighting important clinical data for various treatment options for itch. Practical considerations for increasing the recognition of itch as well as improving its management in psoriasis are also provided.

Kadsura heteroclita stem suppresses the onset and progression of adjuvant-induced arthritis in rats

BACKGROUND

Rheumatoid arthritis (RA) is a chronic autoimmune diseased state, characterized by hyperplasia of the synovial membrane, degradation of cartilage, and bone erosion of diarthrodial joints. Kadsura heteroclita (Roxb) Craib (Schizandraceae), a traditional Tujia ethnomedicine called Xue Tong in China, has been long used for the prevention and treatment of rheumatic and arthritic diseases, especially in the southern China. This study aimed to evaluate anti-arthritic effects of the ethanol extract of Kadsura heteroclita stems (KHS) on complete Freund's adjuvant (CFA)-induced arthritis (AIA) in rats, as well as to explore the underlying mechanisms of anti-arthritis.

METHODS

AIA was established in male Sprague-Dawley (SD) rats as described previously, and animals were daily treated by gavage with KHS ethanol extract (200, 400, or 800 mg/kg) or vehicle (0.3% CMCNa) throughout the 30-day experiment. The incidence and severity of arthritis were evaluated using clinical parameters. At the end of experiments, tissue swelling and bone destruction of the hind paws were assessed by computed tomography (CT) and histopathological analyses. Serum levels of tumor necrosis factor (TNF-α), interleukin-1β (IL-1β), IL-6, and IL-17A and IL-17F were measured by ELISA, and protein expression of matrix metalloproteinases-1 (MMP-1), MMP-3 and tissue inhibitor of MMP-1 (TIMP-1) were detected by Western blot.

RESULTS

Treatment with KHS dose-dependently inhibited paw swelling and reduced arthritis scores of AIA rats. CT images displayed that KHS remarkably protected AIA rats from tissue swelling and bone erosion of joints. Histopathological analyses revealed that KHS markedly reduced inflammatory cell infiltration, synovial proliferation, and the formation of pannus in the ankle joints of AIA rats. KHS was found to significantly suppress the production of TNF-α, IL-1 β, IL-6, IL-17A and IL-17F, inhibited the protein expression of MMP-1 and MMP-3, and elevated the protein expressions of TIMP-1.

CONCLUSION

KHS demonstrates potential anti-arthritic effects via inhibiting pivotal mediators of inflammation and cartilage destruction. This study strongly supports identification and isolation of active fractions of KHS which would be a potential candidate for further investigation as a new anti-arthritic botanical drug.

Role and mechanisms of cytokines in the secondary brain injury after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a common and severe cerebrovascular disease that has high mortality. Few survivors achieve self-care. Currently, patients receive only symptomatic treatment for ICH and benefit poorly from this regimen. Inflammatory cytokines are important participants in secondary injury after ICH. Increases in proinflammatory cytokines may aggravate the tissue injury, whereas increases in anti-inflammatory cytokines might be protective in the ICH brain. Inflammatory cytokines have been studied as therapeutic targets in a variety of acute and chronic brain diseases; however, studies on ICH are limited. This review summarizes the roles and functions of various pro- and anti-inflammatory cytokines in secondary brain injury after ICH and discusses pathogenic mechanisms and emerging therapeutic strategies and directions for treatment of ICH.

The effects of interleukin 17A on left stellate ganglion remodeling are mediated by neuroimmune communication in normal structural hearts

BACKGROUND

It is reported interleukin (IL)-17A, a classical proinflammatory cytokine, is implicated in neuroimmune-associated remodeling in neural plasticity and pathological conditions. However, the effect of IL-17A on left stellate ganglion (LSG) remodeling remains unclear.

OBJECTIVE

This study was performed to determine whether exogenous IL-17A promotes LSG remodeling and destabilize ventricular electrophysiological properties (EPs) in normal canines.

METHODS

24 beagles were randomly allocated into three groups. In the first group, animals were subjected to 0.1 ml phosphate buffer saline (PBS) microinjection of into LSG (n = 8), an equivalent IL-17A was administrated in the second group (n = 8), and an equivalent anti-IL-17A mAb plus IL-17A was administrated in the third group (n = 8). The ventricular EPs, neural function and activity of the LSG were determined at baseline and 30 min after administration. In the end, LSG tissues were collected.

RESULTS

Compared with the control group, the experimental group had a significantly shorter effective refractory period (ERP) and action potential duration (APD)₉₀, an increased ERP, APD₉₀, S_max dispersion, and APD alternans cycle length; and steepened APD restitution curves. In addition, IL-17A enhanced the neural function and activity of the LSG, upregulated the expressions of neuropeptides and proinflammatory cytokines and cells. And all these effects were attenuated by anti-IL-17A mAb. Importantly, IL-17 receptor A (IL-17R-A) was detected in sympathetic neurons in the LSG.

CONCLUSION

IL-17A promoted LSG remodeling by regulating the neural inflammation response. It did so by binding to IL-17R-A, resulting in unstable ventricular electrophysiology in normal structural hearts.

The Antipruritic Effect of Phototherapy

Phototherapy is widely used to treat inflammatory skin diseases such as psoriasis and atopic dermatitis. Repeated suberythemogenic doses of UV-light reduce inflammation in these diseases and ultimately may lead to a complete disappearance of cutaneous symptoms for weeks or months. Chronic pruritus is an important and highly distressing symptom of many of these inflammatory skin diseases. Interestingly, pruritus is also reduced or completely abolished by UV-treatment of psoriasis and atopic dermatitis, and sometimes reduction of pruritus is the first indication for skin improvement by phototherapy. The cutaneous nervous system is an integral part of skin anatomy, and free nerve endings of sensory cutaneous nerve fibers reach up into the epidermis getting in close contact with epidermal cells and mediators from epidermal cells released into the intercellular space. Stimulation of “pruriceptors” within this group of sensory nerve fibers generates a neuronal signal eventually transmitted via the dorsal root and the spinal cord to the brain, where it is recognized as “itch”. UV-light may directly affect cutaneous sensory nerve fibers or, via the release of mediators from cells within the skin, indirectly modulate their function as well as the transmission of itch to the central nervous system inducing the clinically recognized antipruritic effect of phototherapy.

Impact of Ixekizumab Treatment on Itch and Psoriasis Area and Severity Index in Patients with Moderate-to-Severe Plaque Psoriasis: An Integrated Analysis of Two Phase III Randomized Studies

INTRODUCTION

We evaluated baseline itch and its impact on the efficacy of ixekizumab (IXE) in clearing psoriasis and improving quality-of-life measures, and we explored the relationship between itch and psoriatic skin improvement.

METHODS

Data were analyzed from two double-blind, randomized, controlled phase III studies (UNCOVER-2/3) comparing etanercept (ETN), IXE, and placebo (PBO) in patients with moderate-to-severe plaque psoriasis. Long-term analysis included UNCOVER-3 data from week 0 to week 156.

RESULTS

At week 12, a clinically meaningful improvement in itch [Itch Numeric Rating Scale (NRS) reduction ≥ 4] was seen in 70.0%, 88.6%, and 90.8% of the IXE-treated patients in the baseline Itch NRS 4-6, 7-8, and 9-10 groups, respectively (all itch severity groups p < 0.001 versus ETN and PBO). Also, 68.9%, 67.1%, and 73.6% of the IXE-treated patients in the baseline Itch NRS 4-6, 7-8, and 9-10 groups, respectively, showed an improvement of ≥ 90.0% in the Psoriatic Area and Severity Index (PASI) at week 12 as compared to the baseline (PASI 90) (all itch severity groups p < 0.001 versus ETN and PBO). For most patients, itch reduction preceded psoriatic plaque improvement. Sustained effects of IXE on itch and PASI were observed during 3 years of treatment.

CONCLUSIONS

Regardless of baseline itch severity, IXE treatment provided a rapid improvement in itch followed by clinically meaningful improvements in psoriasis.

FUNDING

Eli Lilly and Company.

TRIAL REGISTRATION

ClinicalTrials.gov identifiers, NCT01597245 and NCT01646177.

TH17 cells mediate inflammation in a novel model of spontaneous experimental autoimmune lacrimal keratoconjunctivitis with neural damage

BACKGROUND

Dry eye disease (DED) affects one third of the population worldwide. In prior studies, experimental autoimmune lacrimal keratoconjunctivitis (EALK) induced by desiccating stress in mice has been used as a model of DED. This model is complicated by a requirement for exogenous epithelial cell injury and administration of anticholinergic agents with broad immunologic effects.

OBJECTIVE

We sought to develop a novel mouse model of EALK and to demonstrate the responsible pathogenic mechanisms.

METHODS

CD4+CD45RBhigh naive T cells with and without CD4+CD45RBlow regulatory T cells were adoptively transferred to C57BL/10 recombination-activating gene 2 (Rag2)-/- mice. The eyes, draining lymph nodes, lacrimal glands, and surrounding tissues of mice with and without spontaneous keratoconjunctivitis were evaluated for histopathologic changes, cellular infiltration, and cytokine production in tissues and isolated cells. Furthermore, the integrity of the corneal nerves was evaluated using whole-tissue immunofluorescence imaging. Gene-deficient naive T cells or RAG2-deficient hosts were evaluated to assess the roles of IFN-γ, IL-17A, and IL-23 in disease pathogenesis. Finally, cytokine levels were determined in the tears of patients with DED.

RESULTS

EALK developed spontaneously in C57BL/10 Rag2-/- mice after adoptive transfer of CD4+CD45RBhigh naive T cells and was characterized by infiltration of CD4+ T cells, macrophages, and neutrophils. In addition to lacrimal keratoconjunctivitis, mice had damage to the corneal nerve, which connects components of the lacrimal functional unit. Pathogenic T-cell differentiation was dependent on IL-23p40 and controlled by cotransferred CD4+CD45RBlow regulatory T cells. TH17 rather than TH1 CD4+ cells were primarily responsible for EALK, even though levels of both IL-17 and IFN-γ were increased in inflammatory tissues, likely because of their ability to drive expression of CXC chemokines within the cornea and the subsequent influx of myeloid cells. Consistent with the findings of this model, the tears of patients with DED had increased levels of inflammatory cytokines, including IL-17A and TNF-α.

CONCLUSION

We describe a novel model of spontaneous EALK that supports a role for TH17 cells in disease pathogenesis and that will contribute to our understanding of autoimmune lacrimal keratoconjunctivitis in many human eye diseases, including DED.

A pilot study on immuno-psychiatry in the 22q11.2 deletion syndrome: A role for Th17 cells in psychosis?

BACKGROUND

A growing body of evidence supports a role for immune alterations in Schizophrenia Spectrum Disorders (SSD). A high prevalence (25-40%) of SSD has been found in patients with 22q11.2 deletion syndrome (22q11.2DS), which is known for T-cell deficits due to thymus hypoplasia. This study is the first to explore the association between the T-cell subsets and psychotic symptoms in adults with 22q11.2DS.

METHODS

34 individuals (aged 19-38 yrs.) with 22q11.2DS and 34 healthy age- and gender matched control individuals were included. FACS analysis of the blood samples was performed to define T-cell subsets. Ultra-high risk for psychosis or diagnosis of SSD was determined based on CAARMS interviews and DSM-5 criteria for SSD. Positive psychotic symptom severity was measured based on the PANSS positive symptoms subscale.

RESULTS

A partial T-cell immune deficiency in 22q11.2DS patients was confirmed by significantly reduced percentages of circulating T and T-helper cells. Significantly higher percentages of inflammatory Th1, Th17, and memory T-helper cells were found in adults with 22q11.2DS. Most importantly an increased Th17 percentage was found in adults with psychotic symptoms as compared to non-psychotic adults with 22q11.2DS, and Th17 percentage were related to the presence of positive psychotic symptoms.

CONCLUSIONS

Given the literature on the role of T cells and in particular of Th17 cells and IL-17 in hippocampus development, cognition and behavior, these results support the hypothesis for a role of Th17 cells in the development and/or regulation of psychotic symptoms in 22q11.2DS. This pilot study underlines the importance to further study the role of T-cell defects and of Th17 cells in the development of psychiatric symptoms. It also supports the possibility to use 22q11.2DS as a model to study T-cell involvement in the development of SSD.

Improvement in itch and other psoriasis symptoms with brodalumab in phase 3 randomized controlled trials

BACKGROUND

Patients with psoriasis have lesional symptoms, including itch, which can reduce quality of life. The efficacy and safety of brodalumab, an interleukin-17 receptor A antagonist, in treating moderate-to-severe psoriasis have been reported in three randomized, controlled, phase 3 trials (AMAGINE-1/-2/-3).

OBJECTIVE

The effect of brodalumab on lesional symptoms was assessed using the psoriasis symptom inventory (PSI), a validated patient-reported instrument.

METHODS

Patients were randomized to receive brodalumab (140 or 210 mg every 2 weeks [Q2W]), placebo (AMAGINE-1/-2/-3), or ustekinumab (AMAGINE-2/-3) during a 12-week induction phase, followed by a maintenance phase through week 52. Patients electronically rated the severity of PSI items (itch, burning, stinging, pain, redness, scaling, cracking and flaking) during the previous 24 h on a scale of 0 (not at all severe) to 4 (very severe). At each visit, the PSI total score responder status was assessed, with responders defined as having an average weekly total inventory score ≤8 with no item score >1 at week 12.

RESULTS

Across AMAGINE-1/-2/-3, brodalumab was associated with improvements in PSI total scores and itch scores vs. placebo from week 2 through week 12 (P < 0.001 in both domains). In AMAGINE-2/-3, brodalumab 210 mg Q2W demonstrated faster onset of PSI total score and itch responses (week 2, 22.1% and 36.4%, respectively) vs. ustekinumab (week 2, 6.9% and 17.1%, respectively) and was associated with improved itch responses vs. ustekinumab after 52 weeks of constant treatment.

CONCLUSION

Brodalumab demonstrated rapid, robust improvements in symptoms assessed by the PSI, including itch, vs. placebo and ustekinumab.

Th17 cells in depression

T helper 17 (Th17) cells have recently been implicated in depression, which adds to the list of several other diseases of the central nervous system (CNS) that are already known to involve Th17 cells. In CNS diseases, it is thought that the signature cytokine produced by Th17 cells, interleukin-17A (IL-17A), mediates the detrimental effects of Th17 cells. In depression, although Th17 cells increase, the lack of a consistent correlation between depression severity and blood IL-17A levels suggests that Th17 cells promote depressive symptoms, which may not be entirely dependent on IL-17. However, little is known about the mechanism of action of Th17 cells or the source of CNS Th17 cells in depression. It is likely that Th17 cells promote neuroinflammation and activation of microglia and astrocytes, actions that may contribute to neuronal damage. A source of Th17 cells is the small intestine where they are regulated by the composition of the microbiome. It remains to be determined through what mechanisms of action Th17 cells affect depression and if Th17 cells can be considered a novel therapeutic target in depression.

Immunological profile in cerebrospinal fluid of patients with multiple sclerosis after treatment switch to rituximab and compared with healthy controls

OBJECTIVE

To investigate changes in the cerebrospinal fluid (CSF) immunological profile after treatment switch from first-line injectables to rituximab in patients with relapsing-remitting MS (RRMS), and to compare the profile in MS patients with healthy controls (HC).

METHOD

Cerebrospinal fluid from 70 patients with clinically stable RRMS and 55 HC was analysed by a multiplex electrochemiluminescence method for a broad panel of cytokines and immunoactive substances before, and over a two-year period after, treatment switch to rituximab. After quality assessment of data, using a predefined algorithm, 14 analytes were included in the final analysis.

RESULTS

Ten of the 14 analytes differed significantly in MS patients compared with HC at baseline. Levels of IP-10 (CXCL10), IL-12/23p40, IL-6, sVCAM1, IL-15, sICAM1 and IL-8 (CXCL8) decreased significantly after treatment switch to rituximab. The cytokines IP-10 and IL-12/IL-23p40 displayed the largest difference versus HC at baseline and also the largest relative reduction after therapy switch to rituximab.

CONCLUSION

We found significant changes in the immunological profile after therapy switch to rituximab in RRMS in the direction towards the values of HC. IP-10 and IL12/IL-23p40 deserve further studies as part of the immunopathogenesis of MS as well as for the mode of action of rituximab in MS.

A role for interleukin 17A in IBD-related neuroplasticity

BACKGROUND

Changes to the structure and function of the innervation of the gut contribute to symptom generation in inflammatory bowel diseases (IBD). However, delineation of the mechanisms of these effects has proven difficult. Previous work on sympathetic neurons identified interleukin (IL)-17A as a novel neurotrophic cytokine. Since IL-17A is involved in IBD pathogenesis, we tested the hypothesis that IL-17A contributes to neuroanatomical remodeling during IBD.

METHODS

Immunohistochemistry for tyrosine hydroxylase was used to identify sympathetic axons in mice with dextran sulphate sodium (DSS)-induced colitis and controls. Axon outgrowth from sympathetic neurons in response to incubation in cytokines or endoscopic patient biopsy supernatants was quantified.

KEY RESULTS

DSS-induced colitis led to an increase in tyrosine hydroxylase immunoreactivity in the inflamed colon but not the spleen. Colonic supernatants from mice with colitis and biopsy supernatants from Crohn's disease patients increased axon outgrowth from mouse sympathetic neurons compared to supernatants from uninflamed controls. An antibody that neutralized IL-17A blocked the ability of DSS-induced colitis and Crohn's disease supernatants to induce axon extension.

CONCLUSIONS AND INFERENCES

These findings identify IL-17A as a potential mediator of neuroanatomical remodeling of the gut innervation during IBD.

Expression, Regulation, and Effects of Interleukin-17f in the Human Ocular Surface

PURPOSE

To evaluate the basal and possibly stimulated expression of interleukin (IL)-17 in the context of the ocular surface and potential downstream effects.

METHODS

Western blot and immunofluorescent staining were used to evaluate IL-17F expression in human cornea/conjunctival tissues and cornea epithelial cell line. Cytokines and matrix metalloproteinase (MMP) transcripts were quantified by qPCR. IL-17F effects on NF-κB were investigated by the secretary alkaline phosphatase assay.

RESULTS

IL-17F was expressed in the cytoplasm of human corneal and conjunctival epithelial tissues. In the corneal cell line, exogenous IL-17F did not increase the NF-κB activity, but Pam3CSK4 increased IL-17F transcripts. IL-17F stimulated MMP-9 activity, promoted IL-6, IL-8, tumor necrosis factor-α transcripts levels, and depressed monocyte chemoattractant protein-1 expression, but did not affect transforming growth factor beta-1 transcript levels.

CONCLUSIONS

Normal corneal/conjunctival epithelial cells express IL-17F. Microbial agents may stimulate IL-17F via the NF-κB pathway. Matrix dissolution stimulated by IL-17F may have a role in the melting and necrosis of cornea in severe inflammation.