Mast cells and inflammation

Mast Cells as a Target-A Comprehensive Review of Recent Therapeutic Approaches

Mast cells (MCs) are the immune cells distributed throughout nearly all tissues, mainly in the skin, near blood vessels and lymph vessels, nerves, lungs, and the intestines. Although MCs are essential to the healthy immune response, their overactivity and pathological states can lead to numerous health hazards. The side effect of mast cell activity is usually caused by degranulation. It can be triggered by immunological factors, such as immunoglobulins, lymphocytes, or antigen-antibody complexes, and non-immune factors, such as radiation and pathogens. An intensive reaction of mast cells can even lead to anaphylaxis, one of the most life-threatening allergic reactions. What is more, mast cells play a role in the tumor microenvironment by modulating various events of tumor biology, such as cell proliferation and survival, angiogenesis, invasiveness, and metastasis. The mechanisms of the mast cell actions are still poorly understood, making it difficult to develop therapies for their pathological condition. This review focuses on the possible therapies targeting mast cell degranulation, anaphylaxis, and MC-derived tumors.

Decreased autophagic activity of detrusor cells is involved in the inflammatory response of interstitial cystitis/bladder pain syndrome

INTRODUCTION AND HYPOTHESIS

Genome-wide association studies suggest that autophagy plays an important regulatory role in inflammatory and autoimmune diseases. Inflammation and immune regulation disorders are involved in the occurrence and development of interstitial cystitis/bladder pain syndrome (IC/BPS). However, the changes and roles of autophagy in IC/BPS have not been reported. Therefore, this study aimed to investigate bladder autophagy and inflammation changes in patients with IC/BPS.

METHODS

Bladder specimens (n = 5) from patients with cystectomy due to end-stage IC/BPS were collected. The bladder samples of the control group (n = 5) were derived from the normal area bladder tissue after radical cystectomy. H&E and toluidine blue staining were used for histological evaluation. The co-location of LC3, alpha-smooth muscle actin (α-SMA), and autophagosome was investigated with double-labeled immunofluorescence and transmission electron microscopy (TEM). The expression of IL-6, TNF-α, Bax, caspase-3, and BCL-2 in the detrusor layer was analyzed using immunohistochemistry (IHC) and Western blot (WB).

RESULTS

Compared with the control group, bladder tissue from IC/BPS patients revealed thinner and edematous epithelium with many mast cells (P < 0.05) infiltrating into the muscle layer. By using TEM (P < 0.05), double-labeled immunofluorescence (P < 0.05), and Western blot (P < 0.05) in IC/BPS patients, autophagy was also found and was significantly increased in detrusor myocytes. IHC and WB indicate the expression of BCL-2 (P < 0.05) was decreased, while IL-6, TNF-α, Bax, and caspase-3 expression was elevated (P < 0.05).

CONCLUSIONS

The number of autophagosomes in detrusor cells was increased in IC/BPS. However, autophagy of detrusor muscle cells may not have sufficient phagocytic activity to effectively remove damaged proteins and mitochondria, which may lead to the continued deterioration of IC/BPS inflammation and apoptosis.

Pathophysiological Involvement of Mast Cells and the Lipid Mediators in Pulmonary Vascular Remodeling

Mast cells are responsible for IgE-dependent allergic responses, but they also produce various bioactive mediators and contribute to the pathogenesis of various cardiovascular diseases, including pulmonary hypertension (PH). The importance of lipid mediators in the pathogenesis of PH has become evident in recent years, as exemplified by prostaglandin I2, the most central therapeutic target in pulmonary arterial hypertension. New bioactive lipids other than eicosanoids have also been identified that are associated with the pathogenesis of PH. However, it remains largely unknown how mast cell-derived lipid mediators are involved in pulmonary vascular remodeling. Recently, it has been demonstrated that mast cells produce epoxidized n-3 fatty acid (n-3 epoxides) in a degranulation-independent manner, and that n-3 epoxides produced by mast cells regulate the abnormal activation of pulmonary fibroblasts and suppress the progression of pulmonary vascular remodeling. This review summarizes the role of mast cells and bioactive lipids in the pathogenesis of PH. In addition, we introduce the pathophysiological role and therapeutic potential of n-3 epoxides, a mast cell-derived novel lipid mediator, in the pulmonary vascular remodeling in PH. Further knowledge of mast cells and lipid mediators is expected to lead to the development of innovative therapies targeting pulmonary vascular remodeling.

An Innovative Fluid Dynamic System to Model Inflammation in Human Skin Explants

Skin is a major administration route for drugs, and all transdermal formulations must be tested for their capability to overcome the cutaneous barrier. Therefore, developing highly reliable skin models is crucial for preclinical studies. The current in vitro models are unable to replicate the living skin in all its complexity; thus, to date, excised human skin is considered the gold standard for in vitro permeation studies. However, skin explants have a limited life span. In an attempt to overcome this problem, we used an innovative bioreactor that allowed us to achieve good structural and functional preservation in vitro of explanted human skin for up to 72 h. This device was then used to set up an in vitro inflammatory model by applying two distinct agents mimicking either exogenous or endogenous stimuli: i.e., dithranol, inducing the contact dermatitis phenotype, and the substance P, mimicking neurogenic inflammation. Our in vitro system proved to reproduce inflammatory events observed in vivo, such as vasodilation, increased number of macrophages and mast cells, and increased cytokine secretion. This bioreactor-based system may therefore be suitably and reliably used to simulate in vitro human skin inflammation and may be foreseen as a promising tool to test the efficacy of drugs and cosmetics.

Activation of Mast Cells by Neuropeptides: The Role of Pro-Inflammatory and Anti-Inflammatory Cytokines

Mast cells (MCs) are tissue cells that are derived from bone marrow stem cells that contribute to allergic reactions, inflammatory diseases, innate and adaptive immunity, autoimmunity, and mental disorders. MCs located near the meninges communicate with microglia through the production of mediators such as histamine and tryptase, but also through the secretion of IL-1, IL-6 and TNF, which can create pathological effects in the brain. Preformed chemical mediators of inflammation and tumor necrosis factor (TNF) are rapidly released from the granules of MCs, the only immune cells capable of storing the cytokine TNF, although it can also be produced later through mRNA. The role of MCs in nervous system diseases has been extensively studied and reported in the scientific literature; it is of great clinical interest. However, many of the published articles concern studies on animals (mainly rats or mice) and not on humans. MCs are known to interact with neuropeptides that mediate endothelial cell activation, resulting in central nervous system (CNS) inflammatory disorders. In the brain, MCs interact with neurons causing neuronal excitation with the production of neuropeptides and the release of inflammatory mediators such as cytokines and chemokines. This article explores the current understanding of MC activation by neuropeptide substance P (SP), corticotropin-releasing hormone (CRH), and neurotensin, and the role of pro-inflammatory cytokines, suggesting a therapeutic effect of the anti-inflammatory cytokines IL-37 and IL-38.

Role of SARS-CoV-2 Spike-Protein-Induced Activation of Microglia and Mast Cells in the Pathogenesis of Neuro-COVID

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19). About 45% of COVID-19 patients experience several symptoms a few months after the initial infection and develop post-acute sequelae of SARS-CoV-2 (PASC), referred to as "Long-COVID," characterized by persistent physical and mental fatigue. However, the exact pathogenetic mechanisms affecting the brain are still not well-understood. There is increasing evidence of neurovascular inflammation in the brain. However, the precise role of the neuroinflammatory response that contributes to the disease severity of COVID-19 and long COVID pathogenesis is not clearly understood. Here, we review the reports that the SARS-CoV-2 spike protein can cause blood-brain barrier (BBB) dysfunction and damage neurons either directly, or via activation of brain mast cells and microglia and the release of various neuroinflammatory molecules. Moreover, we provide recent evidence that the novel flavanol eriodictyol is particularly suited for development as an effective treatment alone or together with oleuropein and sulforaphane (ViralProtek®), all of which have potent anti-viral and anti-inflammatory actions.

The multifaceted role of mast cells in joint inflammation and arthritis

OBJECTIVE

To review current knowledge surrounding the role of mast cells in joint inflammation and arthritis.

METHOD

Narrative review.

RESULTS

Mast cells (MCs) are commonly observed in the synovium of the joint, particularly surrounding blood vessels and nerve endings. Some studies have reported increased MC number and degranulation in patients with osteoarthritis (OA). In two studies, MCs were the only immune cell type found in higher concentrations in synovium of OA patients compared to rheumatoid arthritis patients. Activation of MCs in OA includes signaling pathways such as immunoglobulin E/Fc epsilon Receptor 1 (IgE/FcεR1), immunoglobulin G/Fc gamma receptor (IgG/FcγR), complement, and toll-like cell surface receptor-mediated signaling, resulting in context-dependent release of either pro-inflammatory and/or anti-inflammatory mediators within the joint. Activation of MCs results in the release of pro-inflammatory mediators that ultimately contribute to inflammation of the synovium, bone remodeling, and cartilage damage. However, some studies have proposed that MCs can also exhibit anti-inflammatory effects by secreting mediators that inactivate pro-inflammatory cytokines such as interleukin 6 (IL-6).

CONCLUSIONS

MCs may play a role in mediating synovial inflammation and OA progression. However, the mechanisms governing MC activation, the downstream pro- and/or anti-inflammatory effects, and their impact on osteoarthritis pathogenesis remains to be elucidated and requires extensive further study. Furthermore, it is important to establish the pathways of MC activation in OA to determine whether MCs exhibit varying phenotypes as a function of disease stage. Ultimately, such research is needed before understanding whether MCs could be targeted in OA treatments.

Euphorbia neriifolia (Indian Spurge Tree): A Plant of Multiple Biological and Pharmacological Activities

Although India has a well-established and growing economy surrounding synthetic drug chemistry with an antibiotic base, a large part of the population, especially in forested villages and tribal belts, is relying solely on plant-derived drugs. This is due to a lower number of side effects, low chances of resistance development against pathogenic microorganisms, as well as the diversity and affordability of such drugs. In the Indian subcontinents, Euphorbia neriifolia Linn. (EN) is one of the valuable plants from the big family of Euphorbiaceae, which is usually found in rocky and hilly areas. E. neriifolia was found to be useful in curing tumors, abdominal swelling, bronchial infection, hydrophobia, earache, cough and cold, asthma, leprosy, gonorrhea, spleen enlargement, leucoderma, snake bites, scorpion stings, and causing appetite improvement, etc. Different in vitro and in vivo experimental studies were performed to determine the antioxidant, anti-diabetic, immunomodulatory, anti-inflammatory, anti-arthritic, wound healing, anti-atherosclerosis, radioprotective, anti-anxiety, anti-convulsant, anti-psychotic, anti-thrombotic, dermal irritation, hemolytic, analgesic, anti-fertility, diuretic, anti-microbial, anti-diarrheal, and anti-carcinogenic activities of the various parts of EN. Several bioactive compounds, such as euphol, nerifoliol, taraxerol, euphonerins A–G, lectin, etc., were isolated from E. neriifolia and need to be investigated further for various biological activities (cardiovascular and neuronal diseases). In the pharmaceutical sector, E. neriifolia was selected for the development of new drugs due to its broad pharmacological activities. Therefore, in the present review, distribution, classification, morphological and microscopical description, phytochemical investigation, pharmacological activities, medicinal uses, harmful effects, and their treatment were evaluated, especially against different lifestyle-related diseases.

Chemically diverse activity-based probes with unexpected inhibitory mechanisms targeting trypsin-like serine proteases

Activity-based probes (ABP) are molecules that bind covalently to the active form of an enzyme family, making them an attractive tool for target and biomarker identification and drug discovery. The present study describes the synthesis and biochemical characterization of novel activity-based probes targeting trypsin-like serine proteases. We developed an extensive library of activity-based probes with "clickable" affinity tags and a diaryl phosphonate warhead. A wide diversity was achieved by including natural amino acid analogs as well as basic polar residues as side chains. A detailed enzymatic characterization was performed in a panel of trypsin-like serine proteases. Their inhibitory potencies and kinetic profile were examined, and their IC50 values, mechanism of inhibition, and kinetic constants were determined. The activity-based probes with a benzyl guanidine side chain showed the highest inhibitory effects in the panel. Surprisingly, some of the high-affinity probes presented a reversible inhibitory mechanism. On the other hand, probes with different side chains exhibited the expected irreversible mechanism. For the first time, we demonstrate that not only irreversible probes but also reversible probes can tightly label recombinant proteases and proteases released from human mast cells. Even under denaturing SDS-PAGE conditions, reversible slow-tight-binding probes can label proteases due to the formation of high-affinity complexes and slow dissociation rates. This unexpected finding will transform the view on the required irreversible nature of activity-based probes. The diversity of this library of activity-based probes combined with a detailed enzyme kinetic characterization will advance their applications in proteomic studies and drug discovery.

The Investigation of Therapeutic Implications of Mast Cell Stabilizer Cromolyn Sodium on Cholestasis and Cholestatic Pruritus in Experimental Cholestasis

BACKGROUND

Relevant studies have indicated that hepatic mast cells may have potential roles in the progression of cholestasis and cholestasis-induced itch. We aimed to compare the effects of cromolyn sodium and other medications on cholestatic pruritus, serum biochemistry, histamine, total bile acids, autotaxin, liver histopathology, and mast cell distribution in tissues in an experimental cholestasis model conducted by bile duct ligation.

METHODS

Rats received the determined treatment consecutively for 10 days in addition to bile duct ligation. On the 5th and 10th days of the experiment, the rats' itching behaviors were observed for 5 minutes. After 10 days, blood and tissue samples were taken.

RESULTS

Significant decreases in serum histamine and autotaxin levels, plasma total bile acids, total bilirubin, and biliary enzymes were reported only in cromolyn sodium-treated rats compared to the control group. In immunohistochemistry of the liver samples, the peribiliary mast cells stained positive for autotaxin. Except for bile duct infarctus, all histopathological findings of cholestasis significantly improved only in cromolyn sodium-treated and sertraline-treated rats. The liver and peritoneal mast cells significantly decreased only in cromolyn sodium-treated rats compared to the control group. On the 10th day of the experiment, the mean duration of itching was significantly lower in all groups, except for naloxone- and ondansetron-treated rats.

CONCLUSION

Cromolyn sodium has promising antipruritic efficacy and provides biochemical and histopathological recovery of the relevant parameters of cholestasis induced by bile duct ligation. For the first time in the literature, we showed that peribiliary mast cells can produce autotaxin, which is a very important pruritogenic signal in the setting of cholestasis.

The sex-dependent response to psychosocial stress and ischaemic heart disease

Stress is an important risk factor for modern chronic diseases, with distinct influences in males and females. The sex specificity of the mammalian stress response contributes to the sex-dependent development and impacts of coronary artery disease (CAD). Compared to men, women appear to have greater susceptibility to chronic forms of psychosocial stress, extending beyond an increased incidence of mood disorders to include a 2- to 4-fold higher risk of stress-dependent myocardial infarction in women, and up to 10-fold higher risk of Takotsubo syndrome-a stress-dependent coronary-myocardial disorder most prevalent in post-menopausal women. Sex differences arise at all levels of the stress response: from initial perception of stress to behavioural, cognitive, and affective responses and longer-term disease outcomes. These fundamental differences involve interactions between chromosomal and gonadal determinants, (mal)adaptive epigenetic modulation across the lifespan (particularly in early life), and the extrinsic influences of socio-cultural, economic, and environmental factors. Pre-clinical investigations of biological mechanisms support distinct early life programming and a heightened corticolimbic-noradrenaline-neuroinflammatory reactivity in females vs. males, among implicated determinants of the chronic stress response. Unravelling the intrinsic molecular, cellular and systems biological basis of these differences, and their interactions with external lifestyle/socio-cultural determinants, can guide preventative and therapeutic strategies to better target coronary heart disease in a tailored sex-specific manner.

Anti-inflammatory and immunomodulatory effects of polysaccharide extracted from Wuguchong (maggot) on 2,4-dinitrochlorobenzene-induced atopic dermatitis in mice

Atopic dermatitis (AD) is an inflammatory, heterogeneous, chronic skin disorder characterized by recurrent eczematous lesions and intense pruritus, and the pathophysiology mechanism of AD is known for immune dysregulation and inflammatory responses. Wuguchong (maggot) has been widely used in the wound field and found with pharmacological properties of the anti-inflammatory and immunomodulatory function. Recently, some polysaccharides were proven to have beneficial effects on AD skin lesions in mice and humans. However, the effect of the polysaccharide extracted from Wuguchong (PEW) on AD remains to be investigated. In the present study, we examined the anti-inflammatory and immunomodulatory effects of PEW on AD and explored the potential mechanisms. Balb/c mice were orally administrated with PEW to evaluate the therapeutic effect of PEW on 2,4-dinitrochlorobenzene (DNCB)-induced AD. Oral PEW administration significantly ameliorated the lesions and symptoms in AD mice, such as the ear thickness and ear swelling degree, epidermal and dermal thickness, and the infiltration of mast cells. In addition, PEW treatment decreased the levels of serum IgE and histamine, the frequencies of Th1 and Th17 cells, as well as the mRNA expression levels of Th1 and Th17 cytokines and nuclear transcript factors (IFN-γ, T-bet, IL-17A, and ROR-rt). Furthermore, the activation of the NF-κB pathway and the phosphorylation of MAPKs (p38, ERK, and JNK) were significantly suppressed by PEW treatment. Taken together, our study suggests that PEW exerts anti-inflammatory and immunomodulatory effects through inhibition of Th1 and Th17 responses and downregulation of NF-κB and MAPK pathways, PEW would be developed as a promising immune therapy for AD.

Drug repurposing: Clemastine fumarate and neurodegeneration

Neurodegenerative diseases have been a weighty problem in elder people who might be stricken with motor or/and cognition defects with lower life quality urging for effective treatment. Drugs are costly from development to market, so that drug repurposing, exploration of existing drugs for novel therapeutic purposes, becomes a wise and popular strategy to raise new treatment options. Clemastine fumarate, different from anti-allergic effect as H1 histamine antagonist, was screened and identified as promising drug for remyelination and autophagy enhancement. Surprisingly, fumarate salt also has similar effect. Hence, whether clemastine fumarate would make a protective impact on neurodegenerative diseases and what contribution fumarate probably makes are intriguing to us. In this review, we summarize the potential mechanism surrounding clemastine fumarate in current literature, and try to distinguish independent or synergistic effect between clemastine and fumarate, aiming to find worthwhile research direction for neurodegeneration diseases.

Acute Inflammation in Tissue Healing

There are well-established links between acute inflammation and successful tissue repair across evolution. Innate immune reactions contribute significantly to pathogen clearance and activation of subsequent reparative events. A network of molecular and cellular regulators supports antimicrobial and tissue repair functions throughout the healing process. A delicate balance must be achieved between protection and the potential for collateral tissue damage associated with overt inflammation. In this review, we summarize the contributions of key cellular and molecular components to the acute inflammatory process and the effective and timely transition toward activation of tissue repair mechanisms. We further discuss how the disruption of inflammatory responses ultimately results in chronic non-healing injuries.

Detrimental effects of simulated microgravity on mast cell homeostasis and function

Exposure to microgravity causes significant alterations in astronauts' immune systems during spaceflight; however, it is unknown whether microgravity affects mast cell homeostasis and activation. Here we show that microgravity negatively regulates the survival and effector function of mast cells. Murine bone marrow-derived mast cells (BMMCs) were cultured with IL-3 in a rotary cell culture system (RCCS) that generates a simulated microgravity (SMG) environment. BMMCs exposed to SMG showed enhanced apoptosis along with the downregulation of Bcl-2, and reduced proliferation compared to Earth's gravity (1G) controls. The reduction in survival and proliferation caused by SMG exposure was recovered by stem cell factor. In addition, SMG impaired mast cell degranulation and cytokine secretion. BMMCs pre-exposed to SMG showed decreased release of β-hexosaminidase, interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) upon stimulation with phorbol 12-myristate-13-acetate (PMA) plus calcium ionophore ionomycin, which correlated with decreased calcium influx. These findings provide new insights into microgravity-mediated alterations of mast cell phenotypes, contributing to the understanding of immune system dysfunction for further space medicine research.

Key Genetic Components of Fibrosis in Diabetic Nephropathy: An Updated Systematic Review and Meta-Analysis

Renal fibrosis (RF) constitutes the common end-point of all kinds of chronic kidney disease (CKD), regardless of the initial cause of disease. The aim of the present study was to identify the key players of fibrosis in the context of diabetic nephropathy (DN). A systematic review and meta-analysis of all available genetic association studies regarding the genes that are included in signaling pathways related to RF were performed. The evaluated studies were published in English and they were included in PubMed and the GWAS Catalog. After an extensive literature review and search of the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, eight signaling pathways related to RF were selected and all available genetic association studies of these genes were meta-analyzed. ACE, AGT, EDN1, EPO, FLT4, GREM1, IL1B, IL6, IL10, IL12RB1, NOS3, TGFB1, IGF2/INS/TH cluster, and VEGFA were highlighted as the key genetic components driving the fibrosis process in DN. The present systematic review and meta-analysis indicate, as key players of fibrosis in DN, sixteen genes. However, the results should be interpreted with caution because the number of studies was relatively small.

Lung Pneumonitis and Fibrosis in Cancer Therapy: A Review on Cellular and Molecular Mechanisms

Fibrosis and pneumonitis are the most important side effects of lung tissue following cancer therapy. Radiotherapy and chemotherapy by some drugs, such as bleomycin, can induce pneumonitis and fibrosis. Targeted therapy and immunotherapy also may induce pneumonitis and fibrosis to a lesser extent compared to chemotherapy and radiotherapy. Activation of lymphocytes by immunotherapy or infiltration of inflammatory cells such as macrophages, lymphocytes, neutrophils, and mast cells following chemo/radiation therapy can induce pneumonitis. Furthermore, the polarization of macrophages toward M2 cells and the release of anti-inflammatory cytokines stimulate fibrosis. Lung fibrosis and pneumonitis may also be potentiated by some other changes such as epithelial-mesenchymal transition (EMT), oxidative stress, reduction/oxidation (redox) responses, renin-angiotensin system, and the upregulation of some inflammatory mediators such as a nuclear factor of kappa B (NF-κB), inflammasome, cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS). Damages to the lung vascular system and the induction of hypoxia also can induce pulmonary injury following chemo/radiation therapy. This review explains various mechanisms of the induction of pneumonitis and lung fibrosis following cancer therapy. Furthermore, the targets and promising agents to mitigate lung fibrosis and pneumonitis will be discussed.

RNA-seq characterization of histamine-releasing mast cells as potential therapeutic target of osteoarthritis

OBJECTIVE

Mast cells in the osteoarthritis (OA) synovium correlate with disease severity. This study aimed to further elucidate the role of mast cells in OA by RNA-Seq analysis and pharmacological blockade of the activity of histamine, a key mast cell mediator, in murine OA.

METHODS

We examined OA synovial tissues and fluids by flow cytometry, immunostaining, single-cell and bulk RNA-Seq, qPCR, and ELISA. Cetirizine, a histamine H1 receptor (H1R) antagonist, was used to treat the destabilization of the medial meniscus (DMM) mouse model of OA.

RESULTS

Flow cytometry and immunohistology analysis of OA synovial cells revealed KIT+ FcεRI+ and TPSAB1+ mast cells. Single-cell RNA-Seq of OA synovial cells identified the expression of prototypical mast cell markers KIT, TPSAB1, CPA3 and HDC, as well as distinctive markers HPGD, CAVIN2, IL1RL1, PRG2, and CKLF, confirmed by bulk RNA-Seq and qPCR. A mast cell prototypical marker expression score classified 40 OA patients into three synovial pathotypes: mast cell-high, -medium, and -low. Additionally, we detected mast cell mediators including histamine, tryptase AB1, CPA3, PRG2, CAVIN2, and CKLF in OA synovial fluids. Elevated H1R expression was detected in human OA synovium, and treatment of mice with the H1 receptor antagonist cetirizine reduced the severity and OA-related mediators in DMM.

CONCLUSION

Based on differential expression of prototypical and distinct mast cell markers, human OA joints can be stratified into mast cell-high, -medium, and -low synovial tissue pathotypes. Pharmacologic blockade of histamine activity holds the potential to improve OA disease outcome.

Mast Cell Cytokines in Acute and Chronic Gingival Tissue Inflammation: Role of IL-33 and IL-37

Much evidence suggests autoimmunity in the etiopathogenesis of periodontal disease. In fact, in periodontitis, there is antibody production against collagen, DNA, and IgG, as well as increased IgA expression, T cell dysfunction, high expression of class II MHC molecules on the surface of gingival epithelial cells in inflamed tissues, activation of NK cells, and the generation of antibodies against the azurophil granules of polymorphonuclear leukocytes. In general, direct activation of autoreactive immune cells and production of TNF can activate neutrophils to release pro-inflammatory enzymes with tissue damage in the gingiva. Gingival inflammation and, in the most serious cases, periodontitis, are mainly due to the dysbiosis of the commensal oral microbiota that triggers the immune system. This inflammatory pathological state can affect the periodontal ligament, bone, and the entire gingival tissue. Oral tolerance can be abrogated by some cytokines produced by epithelial cells and activated immune cells, including mast cells (MCs). Periodontal cells and inflammatory-immune cells, including mast cells (MCs), produce cytokines and chemokines, mediating local inflammation of the gingival, along with destruction of the periodontal ligament and alveolar bone. Immune-cell activation and recruitment can be induced by inflammatory cytokines, such as IL-1, TNF, IL-33, and bacterial products, including lipopolysaccharide (LPS). IL-1 and IL-33 are pleiotropic cytokines from members of the IL-1 family, which mediate inflammation of MCs and contribute to many key features of periodontitis and other inflammatory disorders. IL-33 activates several immune cells, including lymphocytes, Th2 cells, and MCs in both innate and acquired immunological diseases. The classic therapies for periodontitis include non-surgical periodontal treatment, surgery, antibiotics, anti-inflammatory drugs, and surgery, which have been only partially effective. Recently, a natural cytokine, IL-37, a member of the IL-1 family and a suppressor of IL-1b, has received considerable attention for the treatment of inflammatory diseases. In this article, we report that IL-37 may be an important and effective therapeutic cytokine that may inhibit periodontal inflammation. The purpose of this paper is to study the relationship between MCs, IL-1, IL-33, and IL-37 inhibition in acute and chronic inflamed gingival tissue.

Quercetin and Resveratrol Differentially Decrease Expression of the High-Affinity IgE Receptor (FcεRI) by Human and Mouse Mast Cells

Mast cells (MC) synthesize and store proinflammatory mediators and are centrally important in atopic diseases such as asthma and atopic dermatitis. Quercetin a and resveratrol are plant derived polyphenolic compounds with anti-inflammatory properties that inhibit MC degranulation and mediator release. However, the underlying mechanism of these inhibitory effects on MC is poorly understood and it is unclear whether this is a general effect on all MC phenotypes. We have characterized and compared the effects of quercetin with resveratrol on human (LAD2) and mouse (MC/9 and BMMC) MC mediator release, receptor expression and FcεRI signaling to better understand the mechanisms involved in quercetin and resveratrol-mediated inhibition of MC activation. Quercetin significantly decreased the expression of FcεRI by BMMC and MC/9, although the effects on MC/9 were associated with a significant reduction in cell viability. Quercetin also inhibited antigen-stimulated TNF release by BMMC. Although neither quercetin nor resveratrol significantly altered antigen-stimulated BMMC degranulation or downstream signaling events such as phosphorylation of spleen tyrosine kinase (SYK) or extracellular signal-regulated kinase 1/2 (ERK), resveratrol inhibited ERK phosphorylation and FcεRI- stimulated degranulation in LAD2. Our data suggests that quercetin and resveratrol inhibit human and mouse MC differentially and that these effects are associated with modification of FcεRI expression, signaling (phosphorylation of SYK and ERK) and mediator release.

Do mast cells contribute to the continued survival of vertebrates?

This study is an attempt to shed light on why the connective tissue mast cell (MC) is preserved in all species with a blood circulatory system, i.e., the vertebrates since >500 million years, which suggests that the MC performs as yet not understood indispensible life-promoting actions. The literature survey focuses on data in published papers on MC functions in immunological and nonimmunological reactions, host protection, pregnancy, inflammation, and wound healing. All data are thus accessible to the reader. The MC is a secretory cell with a unique mediator profile. A distinctive role for MCs is defined not only by their extensive mediator composition but also by their prominent ability to affect the vasculature to expedite selective cell recruitment and permeability changes and to set the stage for an appropriate acquired response. MCs, harboring a wide range of surface membrane receptors, are activated by the major female sex hormones as well as by diverse potentially adverse stimuli. MC activation/degranulation creates a presumably unique triad tissue response in physiological and pathological situations alike: extracellular matrix degradation and tissue remodeling, de novo cell proliferation, and de novo angiogenesis. As shown in the literature, MC-activation is crucial for successful female reproduction in the mouse, implying one of possibly several yet unidentified physiological roles of MCs. Moreover, the activated MC aids newborns to survive to reproductive age owing to its key beneficial actions in inflammation and wound healing. Thus, a not previously described life-perpetuating loop spanning generations are apparently formed, which, hypothetically, could contribute to the continued survival of the vertebrates.

Anti-inflammatory effects of amarogentin on 2,4-dinitrochlorobenzene-induced atopic dermatitis-like mice and in HaCat cells

BACKGROUND

Amarogentin (AMA) is a secoiridoid glycoside extracted from Swertia and Gentiana roots and exhibits many biological effects such as antioxidative, anti-inflammatory, and antitumor activities. Atopic dermatitis (AD) is a chronic inflammatory skin disease caused by disorders in the regulation of multiple inflammatory cytokines. No effective cure has been found for AD now.

METHODS

We constructed the HaCat and splenocyte model and tested the inhibitory effect of AMA on IL-4, IL-6, and IL-13 secretions using enzyme-linked immunosorbent assay (ELISA). The AD mouse model was constructed and treated with AMA, the severity of skin lesions was observed, epidermal tissue was collected, and epidermal thickness and mast cell infiltration were observed using hematoxylin and eosin and toluidine blue staining, respectively. The expression of kallikrein-related peptidase 7 (KLK7) and filaggrin (FLG) was detected using immunostaining and Western blot analysis. The mRNA expression of KLK7 and FLG was detected using quantitative polymerase chain reaction (qPCR). Blood immunoglobulin E (IgE) secretion was detected.

RESULTS

AMA inhibited IL-6 secreted by tumor necrosis factor (TNF)-α-induced HaCaT cells and reduced IL-4 and IL-13 secreted by phytohemagglutinin (PHA)-induced primary cells in the mice spleen. It was found that the treatment of AMA with 2,4-dinitrochlorobenzene-induced AD-like mice could promote the recovery of dermatitis, reduce the score of dermatitis severity and the scratching frequency, treat the skin lesions, reduce the epidermal thickness, decrease the infiltration of mast cells, reduce the IgE level in serum, decrease the expression levels of AD-related cytokines, increase protein and mRNA expression of FLG, and reduce the protein and mRNA expression of KLK7 in the skin tissues of AD-like mice.

CONCLUSION

In conclusion, AMA inhibits inflammatory response at the cellular level, and AMA reduces the validation response of specific dermatitis mice, relieves pruritus, and repairs the damaged skin barrier.

The rationale for the treatment of long-Covid symptoms – A cardiologist's view

The ongoing coronavirus disease 2019 pandemic left us with thousands of patients suffering from neurological, cardiovascular, and psychiatric disorders named post-acute sequelae of COVID-19 or just long-Covid. In parallel, the vaccination campaigns against SARS-CoV-2 spike protein saved millions of lives worldwide but long-Covid symptoms also appeared rarely following vaccination with a strong overlap to the “canonical” long-Covid symptoms. A therapeutic strategy targeting both, post-VAC and post-SARS-CoV-2 long-Covid symptoms is warranted since exposure to the S-protein either by vaccination or SARS-CoV-2 infection may trigger identical immuno-inflammatory cascades resulting in long-Covid symptoms.

Characterization of Early Inflammatory Events Leading to Provoked Vulvodynia Development in Rats

Background

Provoked vulvodynia (PV) is the main cause of vulvar pain and dyspareunia. The etiology of PV has not yet been elucidated. However, PV is associated with a history of recurrent inflammation, and its often accompanied by increases in the numbers of mast cells (MCs) and sensory hyperinnervation in the vulva. Therefore, this study aimed to examine the role of MCs and the early inflammatory events in the development of chronic vulvar pain in a rat model of PV.

Methods

Mechanical and thermal vulvar sensitivity was measured for 5 months following zymosan vulvar challenges. Vulvar changes in glutamate and nerve growth factor (NGF) were analyzed using ELISA. Immunofluorescence (IF) staining of the vulvar section after 20, 81, and 160 days of the zymosan challenge were performed to test MCs accumulation, hyperinnervation, and expression of pain channels (transient receptor potential vanilloid/ankyrin-1-TRPV1 & TRPA1) in vulvar neurons. Changes in the development of vulvar pain were evaluated following the administration of the MCs stabilizer ketotifen fumarate (KF) during zymosan vulvar challenges.

Results

Zymosan-challenged rats developed significant mechanical and thermal vulvar sensitivity that persisted for over 160 days after the zymosan challenge. During inflammation, increased local concentrations of NGF and glutamate and a robust increase in MCs degranulation were observed in zymosan-challenged rats. In addition, zymosan-challenged rats displayed sensory hyperinnervation and an increase in the expression of TRPV1 and TRPA1. Treatment with KF attenuated the upregulated level of NGF during inflammation, modulated the neuronal modifications, reduced MCs accumulation, and enhanced mechanical hypersensitivity after repeated inflammation challenges.

Conclusion

The present findings suggest that vulvar hypersensitivity is mediated by MCs accumulation, nerve growth, and neuromodulation of TRPV1 and TRPA1. Hence, KF treatment during the critical period of inflammation contributes to preventing chronic vulvar pain development.

Sex Steroids Effects on Asthma: A Network Perspective of Immune and Airway Cells

A multitude of evidence has suggested the differential incidence, prevalence and severity of asthma between males and females. A compilation of recent literature recognized sex differences as a significant non-modifiable risk factor in asthma pathogenesis. Understanding the cellular and mechanistic basis of sex differences remains complex and the pivotal point of this ever elusive quest, which remains to be clarified in the current scenario. Sex steroids are an integral part of human development and evolution while also playing a critical role in the conditioning of the immune system and thereby influencing the function of peripheral organs. Classical perspectives suggest a pre-defined effect of sex steroids, generalizing estrogens popularly under the “estrogen paradox” due to conflicting reports associating estrogen with a pro- and anti-inflammatory role. On the other hand, androgens are classified as “anti-inflammatory,” serving a protective role in mitigating inflammation. Although considered mainstream and simplistic, this observation remains valid for numerous reasons, as elaborated in the current review. Women appear immune-favored with stronger and more responsive immune elements than men. However, the remarkable female predominance of diverse autoimmune and allergic diseases contradicts this observation suggesting that hormonal differences between the sexes might modulate the normal and dysfunctional regulation of the immune system. This review illustrates the potential relationship between key elements of the immune cell system and their interplay with sex steroids, relevant to structural cells in the pathophysiology of asthma and many other lung diseases. Here, we discuss established and emerging paradigms in the clarification of observed sex differences in asthma in the context of the immune system, which will deepen our understanding of asthma etiopathology.

Sword Bean (Canavalia gladiata) Pod Exerts Anti-Allergic and Anti-Inflammatory Effects through Modulation of Th1/Th2 Cell Differentiation

Allergy is an immunoglobulin E (IgE)-mediated process, and its incidence and prevalence have increased worldwide in recent years. Therapeutic agents for allergic diseases are continuously being developed, but side effects follow when used for a long-term use. Therefore, treatments based on natural products that are safe for the body are urgently required. Sword bean (Canavalia gladiata) pod (SBP) has been traditionally used to treat inflammatory diseases, but there is still no scientific basis for its anti-allergic effect. Accordingly, this study investigates the anti-allergic effect and its mechanism of SBP in vitro and in vivo. SBP reduced the nitric oxide production and decreased mRNA and protein expression of inflammatory mediates (inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2)), and inhibited the phosphorylation of nuclear factor kappa B (NF-κB), a major signaling molecule in the inflammatory response. Additionally, SBP extract treatment inhibited phosphatidylinositol-3-kinase/mammalian target of rapamycin (PI3K/mTOR) signaling activity to further inhibit degranulation and allergy mediator generation and control the balance of Th1/Th2 cells, which can induce an allergic reaction when disrupted. Furthermore, the SBP extract exhibited anti-allergic effects in anti-dinitrophenyl IgE-induced RBL-2H3 cells and ovalbumin-treated mice. These findings have potential clinical implications for the treatment as well as prevention of allergic diseases.

Therapeutic application of PPE2 protein of Mycobacterium tuberculosis in inhibiting tissue inflammation

There is an increasing need to develop biological anti-inflammatory agents that are more targeted, effective, and with lesser side effects as compared to conventional chemical drugs. In the present study, we found that Mycobacterium tuberculosis protein PPE2 and a synthetic derivative peptide can suppress the mast cell population and inhibit several vasoactive and fibrogenic mediators and pro-inflammatory cytokines induced by mast cells in formalin-induced tissue injury. PPE2 was found to inhibit transcription from the promoter of stem cell factor, important for mast cell maintenance and migration. Thus, PPE2/peptide can be used as a potent nonsteroidal therapeutic agent for the treatment of inflammation and tissue injury.

Mast cells promote viral entry of SARS-CoV-2 via formation of chymase/spike protein complex

The pulmonary pathological findings associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) result from the release of multiple proinflammatory cytokines, which causes the subsequential damage of the lungs. The current study was undertaken to investigate the responses of mast cells to viral inoculation and their contribution to host defenses from the point of view of viral entry. Pseudovirions, in which the spike glycoprotein of SARS-CoV-2 was incorporated, triggered activation of mast cells, and a mast cell-derived chymase, MCP2, formed a complex with spike protein, which promoted protease-dependent viral entry. According to the quantification results of viral entry, 10 μM quercetin, a mast cell stabilizer, potentially potently inhibited 41.3% of viral entry, while 100 μM chymostatin, which served as a chymase inhibitor, suppressed 52.1% of viral entry, compared to non-treated cells. Study using mast cell-deficient mice showed that the absence of mast cells may influence early viral loading in the upper respiratory tract, which consequently increases the risk of viral invasion into the lower respiratory system. Furthermore, mast cell-deficient mice exhibited ongoing infection in the late phase post-viral inoculation, while clearance of virus-positive cells was observed in wild-type mice. In conclusion, mast cells act as a multifaceted immune modulator that is equipped with both protective effects and pathogenic influences on viral entry of SARS-CoV-2. The utility of mast cell stabilizers and chymase inhibitors in the treatment of SARS-CoV-2-induced acute respiratory syndrome should be optimized regarding the infection stage and the risk of cytokine storm.

Mast Cell Activation Syndrome in COVID-19 and Female Reproductive Function: Theoretical Background vs. Accumulating Clinical Evidence

Coronavirus disease 2019 (COVID-19), a pandemic disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, can affect almost all systems and organs of the human body, including those responsible for reproductive function in women. The multisystem inflammatory response in COVID-19 shows many analogies with mast cell activation syndrome (MCAS), and MCAS may be an important component in the course of COVID-19. Of note, the female sex hormones estradiol (E2) and progesterone (P4) significantly influence mast cell (MC) behavior. This review presents the importance of MCs and the mediators from their granules in the female reproductive system, including pregnancy, and discusses the mechanism of potential disorders related to MCAS. Then, the available data on COVID-19 in the context of hormonal disorders, the course of endometriosis, female fertility, and the course of pregnancy were compiled to verify intuitively predicted threats. Surprisingly, although COVID-19 hyperinflammation and post-COVID-19 illness may be rooted in MCAS, the available clinical data do not provide grounds for treating this mechanism as significantly increasing the risk of abnormal female reproductive function, including pregnancy. Further studies in the context of post COVID-19 condition (long COVID), where inflammation and a procoagulative state resemble many aspects of MCAS, are needed.

TRPV1 SUMOylation suppresses itch by inhibiting TRPV1 interaction with H1 receptors

The molecular mechanism underlying the functional interaction between H1R and TRPV1 remains unclear. We show here that H1R directly binds to the carboxy-terminal region of TRPV1 at residues 715-725 and 736-749. Cell-penetrating peptides containing these sequences suppress histamine-induced scratching behavior in a cheek injection model. The H1R-TRPV1 binding is kept at a minimum at rest in mouse trigeminal neurons due to TRPV1 SUMOylation and it is enhanced upon histamine treatment through a transient TRPV1 deSUMOylation. The knockin of the SUMOylation-deficient TRPV1^K823R mutant in mice leads to constitutive enhancement of H1R-TRPV1 binding, which exacerbates scratching behaviors induced by histamine. Conversely, SENP1 conditional knockout in sensory neurons enhances TRPV1 SUMOylation and suppresses the histamine-induced scratching response. In addition to interfering with binding, TRPV1 SUMOylation promotes H1R degradation through ubiquitination. Our work unveils the molecular mechanism of histaminergic itch by which H1R directly binds to deSUMOylated TRPV1 to facilitate the transduction of the pruritogen signal to the scratching response.

Altered innate immune profile in blood of systemic mastocytosis patients

Background

Mast cells (MC) from systemic mastocytosis (SM) patients release MC mediators that lead to an altered microenvironment with potential consequences on innate immune cells, such as monocytes and dendritic cells (DC). Here we investigated the distribution and functional behaviour of different populations of blood monocytes and DC among distinct diagnostic subtypes of SM.

Methods

Overall, we studied 115 SM patients - 45 bone marrow mastocytosis (BMM), 61 indolent SM (ISM), 9 aggressive SM (ASM)- and 32 healthy donors (HD). Spontaneous and in vitro-stimulated cytokine production by blood monocytes, and their plasma levels, together with the distribution of different subsets of blood monocytes and DCs, were investigated.

Results

SM patients showed increased plasma levels and spontaneous production by blood monocytes of IL1β, IL6, IL8, TNFα and IL10, associated with an exhausted ability of LPS + IFNγ-stimulated blood monocytes to produce IL1β and TGFβ. SM (particularly ISM) patients also showed decreased counts of total monocytes, at the expense of intermediate monocytes and non-classical monocytes. Interestingly, while ISM and ASM patients had decreased numbers of plasmacytoid DC and myeloid DC (and their major subsets) in blood, an expansion of AXL+ DC was specifically encountered in BMM cases.

Conclusion

These results demonstrate an altered distribution of blood monocytes and DC subsets in SM associated with constitutive activation of functionally impaired blood monocytes and increased plasma levels of a wide variety of inflammatory cytokines, reflecting broad activation of the innate immune response in mastocytosis.

Reprograming the immune niche for skin tissue regeneration - From cellular mechanisms to biomaterials applications

Despite the rapid development of therapeutic approaches for skin repair, chronic wounds such as diabetic foot ulcers remain an unaddressed problem that affects millions of people worldwide. Increasing evidence has revealed the crucial and diverse roles of the immune cells in the development and repair of the skin tissue, prompting new research to focus on further understanding and modulating the local immune niche for comprehensive, 'perfect' regeneration. In this review, we first introduce how different immunocytes and certain stromal cells involved in innate and adaptive immunity coordinate to maintain the immune niche and tissue homeostasis, with emphasis on their specific roles in normal and pathological wound healing. We then discuss novel engineering approaches - particularly biomaterials systems and cellular therapies - to target different players of the immune niche, with three major aims to i) overcome 'under-healing', ii) avoid 'over-healing', and iii) promote functional restoration, including appendage development. Finally, we highlight how these strategies strive to manage chronic wounds and achieve full structural and functional skin recovery by creating desirable 'soil' through modulating the immune microenvironment.

Innate Immunity at the Core of Sex Differences in Osteoarthritic Pain?

Osteoarthritis (OA) is a progressive whole-joint disease; no disease-modifying drugs are currently available to stop or slow its process. Symptoms alleviation is the only treatment option. OA is the major cause of chronic pain in adults, with pain being the main symptom driving patients to seek medical help. OA pathophysiology is closely associated with the innate immune system, which is also closely linked to pain mediators leading to joint pain. Pain research has shown sex differences in the biology of pain, including sexually dimorphic responses from key cell types in the innate immune system. Not only is OA more prevalent in women than in men, but women patients also show worse OA outcomes, partially due to experiencing more pain symptoms despite having similar levels of structural damage. The cause of sex differences in OA and OA pain is poorly understood. This review provides an overview of the involvement of innate immunity in OA pain in joints and in the dorsal root ganglion. We summarize the emerging evidence of sex differences regarding innate immunity in OA pain. Our main goal with this review was to provide a scientific foundation for future research leading to alternative pain relief therapies targeting innate immunity that consider sex differences. This will ultimately lead to a more effective treatment of pain in both women and men.

Interactions between Macrophages and Mast Cells in the Female Reproductive System

Mast cells (MCs) and macrophages (Mϕs) are innate immune cells that differentiate from early common myeloid precursors and reside in all body tissues. MCs have a unique capacity to neutralize/degrade toxic proteins, and they are hypothesized as being able to adopt two alternative polarization profiles, similar to Mϕs, with distinct or even opposite roles. Mϕs are very plastic phagocytic cells that are devoted to the elimination of senescent/anomalous endogenous entities (to maintain tissue homeostasis), and to the recognition and elimination of exogenous threats. They can adopt several functional phenotypes in response to microenvironmental cues, whose extreme profiles are the inflammatory/killing phenotype (M1) and the anti-inflammatory/healing phenotype (M2). The concomitant and abundant presence of these two cell types and the partial overlap of their defensive and homeostatic functions leads to the hypothesis that their crosstalk is necessary for the optimal coordination of their functions, both under physiological and pathological conditions. This review will examine the relationship between MCs and Mϕs in some situations of homeostatic regulation (menstrual cycle, embryo implantation), and in some inflammatory conditions in the same organs (endometriosis, preeclampsia), in order to appreciate the importance of their cross-regulation.

Looking for Responders among Women with Chronic Pelvic Pain Treated with a Comicronized Formulation of Micronized Palmitoylethanolamide and Polydatin

Background

Palmitoylethanolamide is reported to solve pain and neuroinflammation in different models of chronic and neurodegenerative diseases. Some concerns have been illustrated for cautiously interpreting the available literature on the topic. Specifically, there is a lack of evidence about palmitoylethanolamide and female chronic pelvic pain. Concerns will be best solved by randomized trials. The present study was aimed at finding the best responders to micronized palmitoylethanolamide in female patient with chronic pelvic pain, using the existing literature at individual patient level, to help further randomized trial planning.

Methods

After a systematic research, eligible studies (the ones enrolled female patients treated for chronic pelvic pain or for dyspareunia, dysuria, dyschezia, and dysmenorrhea with or without chronic pelvic pain) were assessed at individual patient data level. Conditional probabilities were calculated to assess variables conditioning the rates of good responders (pain score points more or equal to 3 reduction), poor responders (2 pain score reduction), and nonresponders at a three-month follow-up.

Results

Only cases treated with palmitoylethanolamide comicronized with polydatin for a short period can be assessed. Good responders are more than 50%. In chronic pelvic pain, there is a 19.0% conditional probability to find good responders among patients with pain score at enrolment of 6 to 8 and of 6.8% to find poor responders among patients with a pain score at enrolment of 6 to 8. Painful disease does not matter on responders' rates.

Conclusion

Best responders to comicronized palmitoylethanolamide/polydatin are patients with pain score higher than 6 at enrolment, irrespective of other variables.

Effects of Dexmedetomidine on Immune Cells: A Narrative Review

As we all know, dexmedetomidine (DEX), as a highly selective α₂ adrenergic receptor agonist, exerts sedative, anti-anxiety and hypnotic effects by inhibiting the discharge of norepinephrine neurons in locus coeruleus and GABA-related hypnotic pathways. However, the role of DEX in anti-inflammatory and immune regulation has gradually attracted the attention of researchers in recent years. The α₂ adrenergic receptor is one of the members of the adrenergic receptor family, which is widely present in a variety of immune cells and mediates the biological behavior of the inflammatory immune system. At present, there have been more and more studies on the effects of DEX on immune cells and inflammatory responses, but few studies have systematically explored the anti-inflammatory and immunomodulatory effects of DEX. Here, we comprehensively review the published human and animal studies related to DEX, summarize the effects of DEX on immune cells and its role in related diseases, and propose potential research direction.

Varied Composition and Underlying Mechanisms of Gut Microbiome in Neuroinflammation

The human gut microbiome has been implicated in a host of bodily functions and their regulation, including brain development and cognition. Neuroinflammation is a relatively newer piece of the puzzle and is implicated in the pathogenesis of many neurological disorders. The microbiome of the gut may alter the inflammatory signaling inside the brain through the secretion of short-chain fatty acids, controlling the availability of amino acid tryptophan and altering vagal activation. Studies in Korea and elsewhere highlight a strong link between microbiome dynamics and neurocognitive states, including personality. For these reasons, re-establishing microbial flora of the gut looks critical for keeping neuroinflammation from putting the whole system aflame through probiotics and allotransplantation of the fecal microbiome. However, the numerosity of the microbiome remains a challenge. For this purpose, it is suggested that wherever possible, a fecal microbial auto-transplant may prove more effective. This review summarizes the current knowledge about the role of the microbiome in neuroinflammation and the various mechanism involved in this process. As an example, we have also discussed the autism spectrum disorder and the implication of neuroinflammation and microbiome in its pathogenesis.

Immune activation in irritable bowel syndrome: what is the evidence?

Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal disorder that is characterized by abdominal pain and an altered defecation pattern. It affects between 5 and 20% of the general population and can seriously impact quality of life. The pathophysiology of IBS is rather complex and multifactorial including, for example, altered signalling by the gut-brain axis, dysbiosis, abnormal visceral pain signalling and intestinal immune activation. The latter has gained particular interest in recent years, with growing insight into the bidirectional communication between the nervous system and the immune system. In this Review, we detail the current evidence suggesting that immune activation contributes to the pathology seen in patients with IBS and discuss the potential mechanisms involved. Moreover, we describe how immune mediators, particularly those released by mast cells, can directly activate or sensitize pain-transmitting nerves, leading to increased pain signalling and abdominal pain. Finally, we discuss the potential of interventions targeting immune activation as a new therapeutic strategy for patients suffering from IBS.

Effect of a Topical Gel Based on Adelmidrol + Trans-Traumatic Acid in the Treatment of Diabetic Foot Ulcers: An Open-Label Study

BACKGROUND

Diabetic foot ulceration is a severe complication of diabetes characterized by chronic inflammation and impaired wound healing. This study aimed to evaluate the effect of a medical device gel based on adelmidrol + trans-traumatic acid in the healing process of diabetic foot ulcers.

METHODS

Thirty-seven diabetic patients with foot ulcers of mild/moderate grade were treated with the gel daily for 4 weeks on the affected area. The following parameters were evaluated at baseline and weekly: 1) wound area, measured by drawing a map of the ulcer and then calculated with photo editing software tools, and 2) clinical appearance of the ulcer, assessed by recording the presence/absence of dry/wet necrosis, infection, fibrin, neoepithelium, exudate, redness, and granulation tissue.

RESULTS

Topical treatment led to progressive healing of diabetic foot ulcers with a significant reduction of the wound area and an improvement in the clinical appearance of the ulcers. No treatment-related adverse events were observed.

CONCLUSIONS

The results of this open-label study show the potential benefits of adelmidrol + trans-traumatic acid topical administration to promote reepithelialization of diabetic foot ulcers. Further studies are needed to confirm the observed results.

Anti-KIT monoclonal antibody CDX-0159 induces profound and durable mast cell suppression in a healthy volunteer study

Background

Mast cells (MC) are powerful inflammatory immune sentinel cells that drive numerous allergic, inflammatory, and pruritic disorders when activated. MC‐targeted therapies are approved in several disorders, yet many patients have limited benefit suggesting the need for approaches that more broadly inhibit MC activity. MCs require the KIT receptor and its ligand stem cell factor (SCF) for differentiation, maturation, and survival. Here we describe CDX‐0159, an anti‐KIT monoclonal antibody that potently suppresses MCs in human healthy volunteers.

Methods

CDX‐0159‐mediated KIT inhibition was tested in vitro using KIT‐expressing immortalized cells and primary human mast cells. CDX‐0159 safety and pharmacokinetics were evaluated in a 13‐week good laboratory practice (GLP)‐compliant cynomolgus macaque study. A single ascending dose (0.3, 1, 3, and 9 mg/kg), double‐blinded placebo‐controlled phase 1a human healthy volunteer study (n = 32) was conducted to evaluate the safety, pharmacokinetics, and pharmacodynamics of CDX‐0159.

Results

CDX‐0159 inhibits SCF‐dependent KIT activation in vitro. Fc modifications in CDX‐0159 led to elimination of effector function and reduced serum clearance. In cynomolgus macaques, multiple high doses were safely administered without a significant impact on hematology, a potential concern for KIT inhibitors. A single dose of CDX‐0159 in healthy human subjects was generally well tolerated and demonstrated long antibody exposure. Importantly, CDX‐0159 led to dose‐dependent, profound suppression of plasma tryptase, a MC‐specific protease associated with tissue MC burden, indicative of systemic MC suppression or ablation.

Conclusion

CDX‐0159 administration leads to systemic mast cell ablation and may represent a safe and novel approach to treat mast cell‐driven disorders.

Effects of Inflammation on Hemostasis in Acutely Ill Patients with Liver Disease

Patients with liver diseases are in a rebalanced state of hemostasis, due to simultaneous decline in pro- and anticoagulant factors. This balance seems to remain even in the sickest patients, but is less stable and might destabilize when patients develop disease complications. Patients with acute decompensation of cirrhosis, acute-on-chronic liver failure, or acute liver failure often develop complications associated with changes in the hemostatic system, such as systemic inflammation. Systemic inflammation causes hemostatic alterations by adhesion and aggregation of platelets, release of von Willebrand factor (VWF), enhanced expression of tissue factor, inhibition of natural anticoagulant pathways, and inhibition of fibrinolysis. Laboratory tests of hemostasis in acutely-ill liver patients may indicate a hypocoagulable state (decreased platelet count, prolongations in prothrombin time and activated partial thromboplastin time, decreased fibrinogen levels) due to decreased synthetic liver capacity or consumption, or a hypercoagulable state (increased VWF levels, hypofibrinolysis in global tests). Whether these changes are clinically relevant and should be corrected with antithrombotic drugs or blood products is incompletely understood. Inflammation and activation of coagulation may cause local ischemia, progression of liver disease, and multiorgan failure. Anti-inflammatory treatment in acutely-ill liver patients may be of potential interest to prevent thrombotic or bleeding complications and halt progression of liver disease.

Pain and Cellular Migration Induced by Bothrops jararaca Venom in Mice Selected for an Acute Inflammatory Response: Involvement of Mast Cells

Bothrops jararaca venom (BjV) can induce mast cell degranulation. In order to investigate the role of mast cells and the interference of the host genetic background in the inflammation induced by BjV, we have used mouse strains selected for maximal (AIRmax) or minimal (AIRmin) acute inflammatory response (AIR). Mice were pretreated with an inhibitor of mast cell degranulation, cromolyn (CROM), and injected in footpads or intraperitoneally (i.p.) with BjV. Pain was measured with von Frey hairs, cell migration in the peritoneum by flow cytometry, and reactive oxygen species (ROS) production by chemiluminescence assays. The nociceptive response to BjV was higher in AIRmax than AIRmin mice; however, this difference was abolished by pretreatment with CROM. BjV induced peritoneal neutrophil (CD11b+ GR-1+) infiltration and ROS secretion in AIRmax mice only, which were partially inhibited by CROM. Our findings evidence a role for mast cells in pain, neutrophil migration, and ROS production triggered by BjV in AIRmax mice that are more susceptible to the action of BjV.

Voluntary Wheel Running Reduces Vesicle Development in an Endometriosis Animal Model Through Modulation of Immune Parameters

Introduction

Endometriosis is a chronic gynecological disorder characterized by the growth of endometrial glands and stroma outside the endometrial cavity producing inflammation and pain. Previously we demonstrated that modulation of the hypothalamic pituitary adrenal (HPA) axis exacerbates the development and severity of this condition. A physically active lifestyle has been shown to confer health benefits in many chronic conditions by potentially acting as a stress buffer, thus we hypothesized that voluntary physical exercise can “realign/reset” the HPA axis resulting in reduced endometriosis symptoms in an animal model.

Methods

Endometriosis was induced in female Sprague Dawley rats by implanting uterine tissue next to the intestinal mesentery on day 0. Sham controls received sutures only. One group of endometriosis animals had access to a running wheel for 2 weeks prior to endometriosis induction until time of sacrifice at day 60. Sham and endometriosis controls received no exercise. All animals were examined for developed vesicles which were collected and measured. Uterine tissue was analyzed for cellular infiltration. Brain, liver, spleen, adrenal glands, leg muscles, and fat were collected, along with peritoneal fluid and blood.

Results

Endometriosis animals developed vesicles in 86.96% of the implants with significantly increased mesenteric fat compared to sham (p < 0.05). Exposure to exercise significantly decreased the size (p < 0.01) and number (p < 0.05) of vesicles that developed, as well as the mesenteric fat (p < 0.01). Exercised animals had higher levels of lactoferrin in peritoneal fluid, and decreased serum fractalkine and leptin. Exercise significantly increased estrogen alpha receptor expression levels (p < 0.01), while significantly decreasing estrogen receptor beta expression (p < 0.01) and macrophage infiltration (p < 0.05) in vesicles compared to non- exercised animals.

Conclusions

Our results suggest that voluntary physical activity might protect against endometriosis and alleviate the associated inflammation via immune modulation of the HPA axis. This offers the potential for further exploration of exercise as a complementary therapy in endometriosis patients.

Synovial mast cells from knee and hip osteoarthritis: histological study and clinical correlations

PURPOSE

The aim of this study was to investigate the presence of synovial mast cells (MCs) in hip and knee tissue from osteoarthritis (OA) patients and to correlate them with clinical and radiological data.

METHODS

Synovial tissue was obtained during arthroplasty from 60 patients, 30 with knee OA and 30 with hip OA. Control synovial tissue was obtained from 30 patients without OA, 15 undergoing above-knee amputation and 15 receiving a hip replacement for fracture. Before surgery, the radiographic findings were graded according to the Kellgren-Lawrence system and clinical data including pain (VAS) and functional information (KOOS and HOOS) was collected. The tissue was stained with hematoxylin-eosin and toluidine blue for histochemistry and incubated with CD117 and CD31 antibodies for immunohistochemistry. MC and vessel number and synovitis score were determined in all samples.

RESULTS

Mean MC number, synovitis score and vessel number were significantly higher in the OA samples (p < 0.05) than in control tissue. MC number correlated with the synovitis score and disease severity in both patient groups.

CONCLUSIONS

The prevalence of MCs in synovium from OA patients and their association with synovial inflammation and pain suggest a role for them in OA pathophysiology.

Post-HPV-Vaccination Mast Cell Activation Syndrome: Possible Vaccine-Triggered Escalation of Undiagnosed Pre-Existing Mast Cell Disease?

For nearly a decade, case reports and series have emerged regarding dysautonomias-particularly postural orthostatic tachycardia syndrome (POTS)-presenting soon after vaccination against human papilloma virus (HPV). We too have observed a number of such cases (all following vaccination with the Gardasil product), and have found several to have detectable mast cell activation syndrome (MCAS) as well as histories suggesting that MCAS was likely present long before vaccination. We detail 11 such cases here, posing a hypothesis that HPV vaccination (at least with the Gardasil product) may have triggered or exacerbated MCAS in teenagers previously not recognized to have it. Only recently recognized, MCAS is being increasingly appreciated as a prevalent and chronic multisystem disorder, often emerging early in life and presenting with inflammatory ± allergic phenomena following from known mast cell (MC) mediator effects. There is rising recognition, too, of associations of MCAS with central and peripheral neuropathic disorders, including autonomic disorders such as POTS. Given the recognized potential for many antigens to trigger a major and permanent escalation of baseline MC misbehavior in a given MCAS patient, we hypothesize that in our patients described herein, vaccination with Gardasil may have caused pre-existing (but not yet clinically recognized) MCAS to worsen to a clinically significantly degree, with the emergence of POTS and other issues. The recognition and management of MCAS prior to vaccinations in general may be a strategy worth investigating for reducing adverse events following HPV vaccinations and perhaps even other types of vaccinations.

Low Tumor Infiltrating Mast Cell Density Reveals Prognostic Benefit in Cervical Carcinoma

Objectives: Research on the role of mast cells (MCs) in cervical tumor immunity is more limited. Therefore, our study aimed to evaluate the prognostic value of MCs and their correlation with the immune microenvironment of cervical carcinoma (CC). Methods: The Cancer Genome Atlas (TCGA) data was utilized to obtain the degree of immune infiltration of MCs in CC. Meanwhile, this study retrospectively collected patient clinical characteristic data and tissue specimens to further verify the relevant conclusions. Mast cell density (MCD) was measured by the CIBERSORT algorithm in TCGA data and immunohistochemical staining of tryptase in CC tissues. Finally, differentially expressed genes (DEGs) of TCGA data were performed using "limma" packages and key gene modules were identified using the MCODE application in Cytoscape. Results: The results showed MCs were diffusely distributed in CC tissues. Moreover, we found that low tumor-infiltrating MCD was beneficial for overall survival (OS) in the TCGA cohort. Consistent conclusions were also obtained in a clinical cohort. In addition, a total of 305 DEGs were analyzed between the high tumor-infiltrating MCD and low tumor-infiltrating MCD group. Seven key modules, a total of 34 genes, were screened through the MCODE plug-in, which was mainly related to inflammatory response and immune response and closely correlated with cytokines including CSF2, CCL20, IL1A, IL1B, and CXCL8. Conclusion: In short, high tumor-infiltration MCs in CC tissue was associated with worse OS in patients. Furthermore, MCs were closely related to cytokines in the tumor microenvironment, suggesting that they collectively played a role in the immune response of the tumor. Therefore, MCD may be a potential prognostic indicator and immunotherapy target of CC.

Mast Cells Trigger Disturbed Bone Healing in Osteoporotic Mice

Mast cells are important tissue-resident sensor and effector immune cells but also play a major role in osteoporosis development. Mast cells are increased in numbers in the bone marrow of postmenopausal osteoporotic patients, and mast cell-deficient mice are protected from ovariectomy (OVX)-induced bone loss. In this study, we showed that mast cell-deficient Mcpt5-Cre R-DTA mice were protected from OVX-induced disturbed fracture healing, indicating a critical role for mast cells in the pathomechanisms of impaired bone repair under estrogen-deficient conditions. We revealed that mast cells trigger the fracture-induced inflammatory response by releasing inflammatory mediators, including interleukin-6, midkine (Mdk), and C-X-C motif chemokine ligand 10 (CXCL10), and promote neutrophil infiltration into the fracture site in OVX mice. Furthermore, mast cells were responsible for reduced osteoblast and increased osteoclast activities in OVX mice callus, as well as increased receptor activator of NF-κB ligand serum levels in OVX mice. Additional in vitro studies with human cells showed that mast cells stimulate osteoclastogenesis by releasing the osteoclastogenic mediators Mdk and CXCL10 in an estrogen-dependent manner, which was mediated via the estrogen receptor alpha on mast cells. In conclusion, mast cells negatively affect the healing of bone fractures under estrogen-deficient conditions. Hence, targeting mast cells might provide a therapeutic strategy to improve disturbed bone repair in postmenopausal osteoporosis. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Neurogenic Inflammation: The Participant in Migraine and Recent Advancements in Translational Research

Migraine is a primary headache disorder characterized by a unilateral, throbbing, pulsing headache, which lasts for hours to days, and the pain can interfere with daily activities. It exhibits various symptoms, such as nausea, vomiting, sensitivity to light, sound, and odors, and physical activity consistently contributes to worsening pain. Despite the intensive research, little is still known about the pathomechanism of migraine. It is widely accepted that migraine involves activation and sensitization of the trigeminovascular system. It leads to the release of several pro-inflammatory neuropeptides and neurotransmitters and causes a cascade of inflammatory tissue responses, including vasodilation, plasma extravasation secondary to capillary leakage, edema, and mast cell degranulation. Convincing evidence obtained in rodent models suggests that neurogenic inflammation is assumed to contribute to the development of a migraine attack. Chemical stimulation of the dura mater triggers activation and sensitization of the trigeminal system and causes numerous molecular and behavioral changes; therefore, this is a relevant animal model of acute migraine. This narrative review discusses the emerging evidence supporting the involvement of neurogenic inflammation and neuropeptides in the pathophysiology of migraine, presenting the most recent advances in preclinical research and the novel therapeutic approaches to the disease.