Commentary: IL-4 and IL-13 receptors and signaling

Biological Therapy of Severe Asthma with Dupilumab, a Dual Receptor Antagonist of Interleukins 4 and 13

Interleukin-4 (IL-4) and interleukin-13 (IL-13) are key cytokines involved in the pathophysiology of both immune-inflammatory and structural changes underlying type 2 asthma. IL-4 plays a pivotal role in Th2 cell polarization, immunoglobulin E (IgE) synthesis and eosinophil recruitment into the airways. IL-13 synergizes with IL-4 in inducing IgE production and also promotes nitric oxide (NO) synthesis, eosinophil chemotaxis, bronchial hyperresponsiveness and mucus secretion, as well as the proliferation of airway resident cells such as fibroblasts and smooth muscle cells. The biological effects of IL-4 and IL-13 are mediated by complex signaling mechanisms activated by receptor dimerization triggered by cytokine binding to the α-subunit of the IL-4 receptor (IL-4Rα). The fully human IgG4 monoclonal antibody dupilumab binds to IL-4Rα, thereby preventing its interactions with both IL-4 and IL-13. This mechanism of action makes it possible for dupilumab to effectively inhibit type 2 inflammation, thus significantly reducing the exacerbation of severe asthma, the consumption of oral corticosteroids (OCS) and the levels of fractional exhaled NO (FeNO). Dupilumab has been approved not only for the add-on therapy of severe asthma, but also for the biological treatment of atopic dermatitis and nasal polyposis.

A Review of the Immunologic Pathways Involved in Bullous Pemphigoid and Novel Therapeutic Targets

Bullous pemphigoid (BP) is a rare, chronic antibody-mediated autoimmune blistering disease primarily affecting the elderly, with an age of onset over 60. Current treatment options are limited and involve the use of corticosteroids and immunosuppressants, but their long-term use is associated with significant morbidity and mortality. In Japan, human intravenous immunoglobin is approved for the treatment of corticosteroid-refractory BP. However, no treatment option is approved by the Food and Drug Administration for the management of BP. Therefore, developing effective therapies free of debilitating side effects is imperative. In this review, we summarize the main immunologic pathways involved in the pathogenesis of BP, with an emphasis on the role of eosinophils, immunoglobulins, cytokines such as the interleukin (IL)-4 and IL-5, and complements. We further discuss the latest advances with novel therapeutic targets tested for the management of BP. Ongoing efforts are needed to run well-designed controlled trials and test the efficacy and safety of investigational drugs while providing much-needed access to these medications for refractory patients who will not otherwise be able to afford them as off-label prescriptions.

Atopic dermatitis: pathomechanisms and lessons learned from novel systemic therapeutic options

Atopic dermatitis (AD) is a chronic, heterogenous, inflammatory skin disorder associated with a high skin-related health burden, typically starting in childhood and often persisting into adulthood. AD is characterized by a wide range of clinical phenotypes, reflecting multiple underlying pathophysiological mechanisms and interactions between genetics, immune system dysregulation, and environmental factors. In this review, we describe the diverse cellular and molecular mechanisms involved in AD, including the critical role of T cell-driven inflammation, primarily via T helper (Th) 2- and Th17-derived cytokines, many of which are mediated by the Janus kinase (JAK) signaling pathway. These local inflammatory processes interact with sensory neuronal pathways, contributing to the clinical manifestations of AD, including itch, pain, and sleep disturbance. The recent elucidation of the molecular pathways involved in AD has allowed treatment strategies to evolve from broad-acting systemic immunosuppressive therapies to more targeted agents, including JAK inhibitors and cytokine-specific biologic agents. Evidence from the clinical development of these targeted therapies has reinforced and expanded our understanding of the pathophysiological mechanisms underlying AD and holds promise for individualized treatment strategies tailored to specific AD subtypes.

Gliomas: Genetic alterations, mechanisms of metastasis, recurrence, drug resistance, and recent trends in molecular therapeutic options

Glioma is the most common intracranial tumor with poor treatment outcomes and has high morbidity and mortality. Various studies on genomic analyses of glioma found a variety of deregulated genes with somatic mutations including TERT, TP53, IDH1, ATRX, TTN, etc. The genetic alterations in the key genes have been demonstrated to play a crucial role in gliomagenesis by modulating important signaling pathways that alter the fundamental intracellular functions such as DNA damage and repair, cell proliferation, metabolism, growth, wound healing, motility, etc. The SPRK1, MMP2, MMP9, AKT, mTOR, etc., genes, and noncoding RNAs (miRNAs, lncRNAs, circRNAs, etc) were shown mostly to be implicated in the metastases of glioma. Despite advances in the current treatment strategies, a low-grade glioma is a uniformly fatal disease with overall median survival of ∼5-7 years while the patients bearing high-grade tumors display poorer median survival of ∼9-10 months mainly due to aggressive metastasis and therapeutic resistance. This review discusses the spectrum of deregulated genes, molecular and cellular mechanisms of metastasis, recurrence, and its management, the plausible causes for the development of therapy resistance, current treatment options, and the recent trends in malignant gliomas. Understanding the pathogenic mechanisms and advances in molecular genetics would aid in the novel diagnosis, prognosis, and translation of pathogenesis-based treatment opportunities which could pave the way for precision medicine in glioma.

Novel Biological Therapies for Severe Asthma Endotypes

Severe asthma comprises several heterogeneous phenotypes, underpinned by complex pathomechanisms known as endotypes. The latter are driven by intercellular networks mediated by molecular components which can be targeted by specific monoclonal antibodies. With regard to the biological treatments of either allergic or non-allergic eosinophilic type 2 asthma, currently available antibodies are directed against immunoglobulins E (IgE), interleukin-5 (IL-5) and its receptor, the receptors of interleukins-4 (IL-4) and 13 (IL-13), as well as thymic stromal lymphopoietin (TSLP) and other alarmins. Among these therapeutic strategies, the best choice should be made according to the phenotypic/endotypic features of each patient with severe asthma, who can thus respond with significant clinical and functional improvements. Conversely, very poor options so far characterize the experimental pipelines referring to the perspective biological management of non-type 2 severe asthma, which thereby needs to be the focus of future thorough research.

MarvelD3 Is Upregulated in Ulcerative Colitis and Has Attenuating Effects during Colitis Indirectly Stabilizing the Intestinal Barrier

In inflammatory bowel disease (IBD), the impaired intestinal barrier is mainly characterized by changes in tight junction protein expression. The functional role of the tight junction-associated MARVEL protein MARVELD3 (MD3) in IBD is yet unknown. (i) In colon biopsies from IBD patients we analyzed MD3 expression and (ii) in human colon HT-29/B6 cells we studied the signaling pathways of different IBD-relevant cytokines. (iii) We generated a mouse model with intestinal overexpression of MD3 and investigated functional effects of MD3 upregulation. Colitis, graded by the disease activity index, was induced by dextran sodium sulfate (DSS) and the intestinal barrier was characterized electrophysiologically. MD3 was upregulated in human ulcerative colitis and MD3 expression could be increased in HT-29/B6 cells by IL-13 via the IL13Rα1/STAT pathway. In mice DSS colitis, MD3 overexpression had an ameliorating, protective effect. It was not based on direct enhancement of paracellular barrier properties, but rather on regulatory mechanisms not solved yet in detail. However, as MD3 is involved in regulatory functions such as proliferation and cell survival, we conclude that the protective effects are hardly targeting the intestinal barrier directly but are based on regulatory processes supporting stabilization of the intestinal barrier.

Interleukins 4 and 13 in Asthma: Key Pathophysiologic Cytokines and Druggable Molecular Targets

Interleukins (IL)-4 and -13 play a pivotal role in the pathobiology of type-2 asthma. Indeed, IL-4 is crucially involved in Th2 cell differentiation, immunoglobulin (Ig) class switching and eosinophil trafficking. IL-13 cooperates with IL-4 in promoting IgE synthesis, and also induces nitric oxide (NO) production, goblet cell metaplasia and fibroblast proliferation, as well as elicits contractile responses and hyperplasia of airway smooth muscle cells.

IL-4 and IL-13 share common signaling pathways, activated by the binding of both cytokines to receptor complexes including the α-subunit of the IL-4 receptor (IL-4Rα). Therefore, the subsequent receptor dimerization is responsible for the pathophysiologic effects of IL-4 and IL-13. By selectively blocking IL-4Rα, the fully human IgG4 monoclonal antibody dupilumab behaves as a dual receptor antagonist of both IL-4 and IL-13. Through this mechanism of action, dupilumab exerts effective therapeutic actions in type-2 inflammation, thus decreasing asthma exacerbations, FeNO (fractional exhaled NO) levels, and the intake of oral corticosteroids (OCS). In addition to being approved for the add-on biological therapy of severe asthma, dupilumab has also been licensed for the treatment of nasal polyposis and atopic dermatitis.

Role of interleukin-4 and their antagonistic effect in asthma

Asthma is a chronic inflammatory disease of the lower airways, characterize by wheezing cough, chest tightness along with inflammation of airway and shortness of breath. Allergens like environmental substance are predispose asthmatics patients to allergy. Mast cells produced interleukin (IL)- 4 which either activate signal transducer and activator of transcription 6 (STAT-6) pathway that involved in differentiation of na ve T-cells to TH2 or activation of TH2 cells indirectly. The aim of the current context is to present role of IL-4 in asthma and effect as antagonist. IL-4 results in increased mucus production and involve in IgE synthesis from B cells. IL4 facilitate chemotaxis and aid in displaying of VCAM-1 which attract eosinophil basophils monocytes T-lymphocytes to blood vessel. IL4 inhibit apoptosis either by preventing decrease in BCL-2 level or binding of FasL to Fas (cd32) receptor which result in acute allergic response. Elevated level of IL-4 has greatly adverse impact on asthmatic patients so by decreasing the level of IL-4 will greatly reduce asthma phenotype.

Inhibition of STAT6 Activation by AS1517499 Inhibits Expression and Activity of PPARγ in Macrophages to Resolve Acute Inflammation in Mice

Signal transducer and activator of transcription 6 (STAT6) promotes an anti-inflammatory process by inducing the development of M2 macrophages. We investigated whether modulating STAT6 activity in macrophages using AS1517499, the specific STAT6 inhibitor, affects the restoration of homeostasis after an inflammatory insult by regulating PPARγ expression and activity. Administration of AS1517499 suppressed the enhanced STAT6 phosphorylation and nuclear translocation observed in peritoneal macrophages after zymosan injection. In addition, AS1517499 delayed resolution of acute inflammation as evidenced by enhanced secretion of pro-inflammatory cytokines, reduced secretion of anti-inflammatory cytokines in PLF and supernatants from peritoneal macrophages, and exaggerated neutrophil numbers and total protein levels in PLF. We demonstrate temporal increases in annexin A1 (AnxA1) protein and mRNA levels in peritoneal lavage fluid (PLF), peritoneal macrophages, and spleen in a murine model of zymosan-induced acute peritonitis. In vitro priming of mouse bone marrow-derived macrophages (BMDM) and peritoneal macrophages with AnxA1 induced STAT6 activation with enhanced PPARγ expression and activity. Using AS1517499, we demonstrate that inhibition of STAT6 activation delayed recovery of PPARγ expression and activity, as well as impaired efferocytosis. Taken together, these results suggest that activation of the STAT6 signaling pathway mediates PPARγ expression and activation in macrophages to resolve acute inflammation.

The Role of T Lymphocytes in Cutaneous Scarring

Significance: Cutaneous scarring affects millions of patients worldwide and results in significant financial and psychosocial burdens. Given the immune system's intricate involvement in the initiation and progression of wound healing, it is no surprise that the scarring outcome can be affected by the actions of various immune cells and the cytokines and growth factors they produce. Understanding the role of T cells in regulating immune responses and directing the action of wound mesenchymal cells is essential to developing antifibrotic therapies to reduce the burden of scarring. Recent Advances: As the immune system is intimately involved in wound healing, much work has examined the impact of T cells and their cytokines on the final wound outcome. New innovative tools for studying T cells have resulted in more sophisticated immunophenotyping capabilities and the ability to examine effects of individual cytokines in the wound environment. Critical Issues: Despite continued advances in the study of specific immune cells and their effects on dermal fibrosis, minimal progress has been made to modulate immune responses to result in improved wound cosmesis. Future Directions: The actions of T cells represent potential pharmacologic targets that could lead to novel bioengineered or immunoengineered therapies to improve the lives of people with cutaneous scarring.

Immunomodulatory potential of in vivo natural killer T (NKT) activation by NKTT320 in Mauritian-origin cynomolgus macaques

Invariant natural killer T-lymphocytes (iNKT) are unique immunomodulatory innate T cells with an invariant TCRα recognizing glycolipids presented on MHC class-I-like CD1d molecules. Activated iNKT rapidly secrete pro-and anti-inflammatory cytokines, potentiate immunity, and modulate inflammation. Here, we report the effects of in vivo iNKT activation in Mauritian-origin cynomolgus macaques by a humanized monoclonal antibody, NKTT320, that binds to the invariant region of the iNKT TCR. NKTT320 led to rapid iNKT activation, increased polyfunctionality, and elevation of multiple plasma analytes within 24 hours. Flow cytometry and RNA-Seq confirmed downstream activation of multiple immune subsets, enrichment of JAK/STAT and PI3K/AKT pathway genes, and upregulation of inflammation-modulating genes. NKTT320 also increased iNKT frequency in adipose tissue and did not cause iNKT anergy. Our data indicate that NKTT320 has a sustained effect on in vivo iNKT activation, potentiation of innate and adaptive immunity, and resolution of inflammation, which supports its future use as an immunotherapeutic.

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NKTT320 rapidly activates iNKT in vivo, modulating downstream immune function

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In vivo NKTT320 treatment modulates pro- and anti-inflammatory genes

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NKTT320 treatment results in activation of innate and adaptive immune subsets

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NKTT320 has promise as an immunotherapeutic with translational potential

Genetic Variants of Interleukin-4 in Romanian Patients with Idiopathic Nephrotic Syndrome

Background and objectives: One of the most frequent glomerular diseases in the pediatric population is represented by the idiopathic nephrotic syndrome (INS). The exact mechanisms mediating the disease are still unknown, but several genetic factors have been studied for possible implications. Cytokines are considered to play a pivotal role in mediating INS disease progression, interleukin-4 (IL-4) exhibiting particular interest. The objective of this research project was to investigate the association between two IL-4 gene single-nucleotide polymorphisms (SNPs) and INS susceptibility as well as response to steroid therapy, in a group of Romanian children. Materials and Methods: In total, 75 patients with INS and 160 healthy controls of Romanian origin were genotyped for IL-4 rs2243250/−590C/T and rs2070874/−34C/T using real-time polymerase chain reaction. Association tests were performed using the DeFinetti program and Plink 1.07 software and p-values < 0.05 were considered statistically significant. Results: The analysis of INS patients and controls revealed a similar genotype distribution of the studied SNPs. The minor T alleles were less frequent in the INS group, but not statistically significant (p = 0.1, OR = 0.68 and p = 0.2, OR = 0.74). Regarding the response to steroids, a low frequency of 590*T allele in steroid-resistant patients (7.7%), compared with steroid-sensitive patients (14%) and controls (17.5%), was obtained, but the difference did not reach the statistical significance threshold. The same result was obtained for −34C/T SNP. Conclusions: This is the first study examining the relationship between the IL-4 gene and INS susceptibility conducted in a European population, and particularly in Romania. The investigated SNPs were found to not be associated with disease susceptibility or response to the steroid treatment of pediatric INS.

ALM Fluid Therapy Shifts Sympathetic Hyperactivity to Parasympathetic Dominance in the Rat Model of Non-Compressible Hemorrhagic Shock

ABSTRACT

Excessive sympathetic outflow following trauma can lead to cardiac dysfunction, inflammation, coagulopathy, and poor outcomes. We previously reported that buprenorphine analgesia decreased survival after hemorrhagic trauma. Our aim is to examine the underlying mechanisms of mortality in a non-compressible hemorrhage rat model resuscitated with saline or adenosine, lidocaine, magnesium (ALM). Anesthetized adult male Sprague-Dawley rats were randomly assigned to Saline control group or ALM therapy group (both n = 10). Hemorrhage was induced by 50% liver resection. After 15 min, 0.7 mL/kg 3% NaCl ± ALM intravenous bolus was administered, and after 60 min, 0.9% NaCl ± ALM was infused for 4 h (0.5 mL/kg/h) with 72 h monitoring. Animals received 6-12-hourly buprenorphine for analgesia. Hemodynamics, heart rate variability, echocardiography, and adiponectin were measured. Cardiac tissue was analyzed for adrenergic/cholinergic receptor expression, inflammation, and histopathology. Four ALM animals and one Saline control survived to 72 h. Mortality was associated with up to 97% decreases in adrenergic (β-1, α-1A) and cholinergic (M2) receptor expression, cardiac inflammation, myocyte Ca2+ loading, and histopathology, indicating heart ischemia/failure. ALM survivors had higher cardiac output and stroke volume, a 30-fold increase in parasympathetic/sympathetic receptor expression ratio, and higher circulating adiponectin compared to Saline controls. Paradoxically, Saline cardiac adiponectin hormone levels were higher than ALM, with no change in receptor expression, indicating intra-cardiac synthesis. Mortality appears to be a "systems failure" associated with CNS dysregulation of cardiac function. Survival involves an increased parasympathetic dominance to support cardiac pump function with reduced myocardial inflammation. Increased cardiac α-1A adrenergic receptor in ALM survivors may be significant, as this receptor is highly protective during heart dysfunction/failure.

Commonly expressed key transcriptomic profiles of sepsis in the human circulation and brain via integrated analysis

BACKGROUND

Sepsis is the leading cause of death in intensive care units and is characterized by multiple organ failure, including dysfuction of the immune system and brain. This study aims to determine the differential effect of sepsis on specific circulating immune cell subsets compared with brain transcriptome and identify the genes co-expressed by them, so as to identify key genes and regulatory factors involved in the pathogenesis of sepsis induced brain injury and identify novel therapeutic targets.

METHODS

The GSE133822 and GSE135838 datasets were obtained from the Gene Expression Omnibus (GEO) database and utilized for bioinformatics analyses. Functional enrichment analysis was used to identify commonly expressed genes that were differentially expressed between sepsis patients and non-sepsis patients with critical illness; protein-protein interaction (PPI) networks were also generated. Then, key transcriptomic biomarkers were further validated in an external dataset from the GEO. We also investigated the expression of key mRNAs in peripheral blood mononuclear cells (PBMCs) from sepsis patients by quantitative PCR (qPCR) and an in-vitro model stimulated by lipopolysaccharide (LPS) was generated in brain cell lines.

RESULTS

The transcriptomic profiles of brain tissue were relatively similar as those of specific immune cells. In addition, our validation showed that these key genes were up regulated both in PBMCs in sepsis patients and LPS-treated brain cells.

CONCLUSION

Brain injury in sepsis was correlated with circulating immune responses, and the expression of DEFA3, MMP8, MMP9 and LCN2 might be potential diagnostic biomarkers as well as therapeutic target in septic brain dysfunction.

Development of Recombinant Dihydrolipoamide Dehydrogenase Subunit Vaccine against Vibrio Infection in Large Yellow Croaker

Large yellow croaker (Larimichthys crocea), an economically important marine fish in China, has suffered from serious vibriosis, which has resulted in great economic losses for the large yellow croaker industry. Vaccination has been considered to be a safe and effective method to prevent and control vibriosis. However, due to the complex diversity and serotypes of the Vibrio genus, the progress of Vibrio vaccine development is still slow. In this study, we prepared recombinant Vibrio dihydrolipoamide dehydrogenase (rDLD) protein and investigated its potential as a candidate to be a subunit vaccine against Vibrio. The lysozyme activity and the rDLD-specific antibody level in sera of large yellow croakers immunized with rDLD were significantly higher than those in the control group, and the transcript levels of proinflammatory cytokines (IL-6, IL-8, IL-1β), MHC IIα/β, CD40, CD8α, IL-4/13A, and IL-4/13B were significantly up-regulated in the spleen and head kidney of large yellow croakers immunized with rDLD, suggesting that rDLD could induce both specific and nonspecific immune responses in this species. In addition, rDLD protein increased the survival rate of large yellow croakers against Vibrio alginolyticus and Vibrio parahaemolyticus, with the relative percent of survival (RPS) being 74.5% and 66.9%, respectively. These results will facilitate the development of a potential subunit vaccine against Vibrio in large yellow croaker aquaculture.

Characterization of the effects on pruritus by novel treatments for atopic dermatitis

Chronic pruritus is a common and debilitating symptom in patients with atopic dermatitis and contributes to impairment of quality of life. Effective treatment of pruritus should therefore be one of the main treatment goals in patients with atopic dermatitis. Pathophysiologically, the histamine-independent pruritogens interleukin-31, interleukin-13, and interleukin-4, have been shown to play a major role in atopic dermatitis. All three cytokines can mediate chronic pruritus via Janus kinase 1/2 signaling pathways. Novel drugs target these pathways and have shown rapid and sustained reduction of pruritus in patients with atopic dermatitis in clinical use and in phase II and III clinical trials. Here we summarize the published data on the effects of these drugs on itch parameters such as overall reduction in pruritus intensity and percent of patients with atopic dermatitis achieving a relevant reduction in itch. Each of the novel drugs shows very good effects on pruritus. These data offer hope for an even better and possibly more specific treatment of pruritus in patients with atopic dermatitis in the future. In addition, the different pharmacological approaches give us the chance to learn more about the pathophysiology of pruritus in atopic dermatitis.

Analysis of the immune landscape in virus-induced cancers using a novel integrative mechanism discovery approach

Background

The mechanisms of carcinogenesis from viral infections are extraordinarily complex and not well understood. Traditional methods of analyzing RNA-sequencing data may not be sufficient for unraveling complicated interactions between viruses and host cells. Using RNA and DNA-sequencing data from The Cancer Genome Atlas (TCGA), we aim to explore whether virus-induced tumors exhibit similar immune-associated (IA) dysregulations using a new algorithm we developed that focuses on the most important biological mechanisms involved in virus-induced cancers. Differential expression, survival correlation, and clinical variable correlations were used to identify the most clinically relevant IA genes dysregulated in 5 virus-induced cancers (HPV-induced head and neck squamous cell carcinoma, HPV-induced cervical cancer, EBV-induced stomach cancer, HBV-induced liver cancer, and HCV-induced liver cancer) after which a mechanistic approach was adopted to identify pathways implicated in IA gene dysregulation.

Results

Our results revealed that IA dysregulations vary with the cancer type and the virus type, but cytokine signaling pathways are dysregulated in all virus-induced cancers. Furthermore, we also found that important similarities exist between all 5 virus-induced cancers in dysregulated clinically relevant oncogenic signatures and IA pathways. Finally, we also discovered potential mechanisms for genomic alterations to induce IA gene dysregulations using our algorithm.

Conclusions

Our study offers a new approach to mechanism identification through integrating functional annotations and large-scale sequencing data, which may be invaluable to the discovery of new immunotherapy targets for virus-induced cancers.

Inflammation after spinal cord injury: a review of the critical timeline of signaling cues and cellular infiltration

Traumatic spinal cord injury (SCI) is a devastating neurological condition that results in a loss of motor and sensory function. Although extensive research to develop treatments for SCI has been performed, to date, none of these treatments have produced a meaningful amount of functional recovery after injury. The primary injury is caused by the initial trauma to the spinal cord and results in ischemia, oxidative damage, edema, and glutamate excitotoxicity. This process initiates a secondary injury cascade, which starts just a few hours post-injury and may continue for more than 6 months, leading to additional cell death and spinal cord damage. Inflammation after SCI is complex and driven by a diverse set of cells and signaling molecules. In this review, we utilize an extensive literature survey to develop the timeline of local immune cell and cytokine behavior after SCI in rodent models. We discuss the precise functional roles of several key cytokines and their effects on a variety of cell types involved in the secondary injury cascade. Furthermore, variations in the inflammatory response between rats and mice are highlighted. Since current SCI treatment options do not successfully initiate functional recovery or axonal regeneration, identifying the specific mechanisms attributed to secondary injury is critical. With a more thorough understanding of the complex SCI pathophysiology, effective therapeutic targets with realistic timelines for intervention may be established to successfully attenuate secondary damage.

Homeostatic IL-13 in healthy skin directs dendritic cell differentiation to promote TH2 and inhibit TH17 cell polarization

The signals driving the adaptation of type 2 dendritic cells (DC2s) to diverse peripheral environments remain mostly undefined. We show that differentiation of CD11blo migratory DC2s-a DC2 population unique to the dermis-required IL-13 signaling dependent on the transcription factors STAT6 and KLF4, whereas DC2s in lung and small intestine were STAT6-independent. Similarly, human DC2s in skin expressed an IL-4 and IL-13 gene signature that was not found in blood, spleen and lung DCs. In mice, IL-13 was secreted homeostatically by dermal innate lymphoid cells and was independent of microbiota, TSLP or IL-33. In the absence of IL-13 signaling, dermal DC2s were stable in number but remained CD11bhi and showed defective activation in response to allergens, with diminished ability to support the development of IL-4+GATA3+ helper T cells (TH), whereas antifungal IL-17+RORγt+ TH cells were increased. Therefore, homeostatic IL-13 fosters a noninflammatory skin environment that supports allergic sensitization.

IL4Rα signaling promotes neonatal cardiac regeneration and cardiomyocyte cell cycle activity

Neonatal heart regeneration depends on proliferation of pre-existing cardiomyocytes, yet the mechanisms driving regeneration and cardiomyocyte proliferation are not comprehensively understood. We recently reported that the anti-inflammatory cytokine, interleukin 13 (IL13), promotes neonatal cardiac regeneration; however, the signaling pathway and cell types mediating this regenerative response remain unknown. Here, we hypothesized that expression of the type II heterodimer receptor for IL13, comprised of IL4Rα and IL13Rα1, expressed directly on cardiomyocytes mediates cardiomyocyte cell cycle and heart regeneration in neonatal mice. Our data demonstrate that indeed global deletion of one critical subunit of the type II receptor, IL4Rα (IL4Rα-/-), decreases cardiomyocyte proliferation during early postnatal development and significantly impairs cardiac regeneration following injury in neonatal mice. While multiple myocardial cell types express IL4Rα, we demonstrate that IL4Rα deletion specifically in cardiomyocytes mediates cell cycle activity and neonatal cardiac regeneration. This demonstrates for the first time a functional role for IL4Rα signaling directly on cardiomyocytes in vivo. Reciprocally, we examined the therapeutic benefit of activating the IL4Rα receptor in non-regenerative hearts via IL13 administration. Following myocardial infarction, administration of IL13 reduced scar size and promoted cardiomyocyte DNA synthesis and karyokinesis, but not complete cytokinesis, in 6-day old non-regenerative mice. Our data demonstrate a novel role for IL4Rα signaling directly on cardiomyocytes during heart regeneration and suggest the potential for type II receptor activation as one potential therapeutic target for promoting myocardial repair.

IL-4 and IL-13 Promote Proliferation of Mammary Epithelial Cells through STAT6 and IRS-1

T helper (Th)2 cytokines such as interleukin (IL)-4 and IL-13 control immune function by acting on leukocytes. They also regulate multiple responses in non-hematopoietic cells. During pregnancy, IL-4 and IL-13 facilitate alveologenesis of mammary glands. This particular morphogenesis generates alveoli from existing ducts and requires substantial cell proliferation. Using 3D cultures of primary mouse mammary epithelial cells, we demonstrate that IL-4 and IL-13 promote cell proliferation, leading to enlargement of mammary acini with partially filled lumens. The mitogenic effects of IL-4 and IL-13 are mediated by STAT6 as inhibition of STAT6 suppresses cell proliferation and improves lumen formation. In addition, IL-4 and IL-13 stimulate tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1). Prolonged treatment with these cytokines leads to increased IRS-1 abundance, which, in turn, amplifies IL-4- and IL-13-stimulated IRS-1 tyrosine phosphorylation. Through signaling crosstalk between IL-4/IL-13 and insulin, a hormone routinely included in mammary cultures, IRS-1 tyrosine phosphorylation is further enhanced. Lowering IRS-1 expression reduces cell proliferation, suggesting that IRS-1 is involved in IL-4- and IL-13-stimulated cell proliferation. Thus, a Th2-dominant cytokine milieu during pregnancy confers mammary gland development by promoting cell proliferation.

Treadmill Exercise Attenuates Cerebral Ischemia-Reperfusion Injury by Promoting Activation of M2 Microglia via Upregulation of Interleukin-4

Background: Exercise has been proven to be an effective therapy for stroke by reducing the microglia-initiated proinflammatory response. Few studies, however, have focused on the phenotypic changes in microglia cells caused by exercise training. The present study was designed to evaluate the influence of treadmill exercise on microglia polarization and the molecular mechanisms involved. Methods: Male Sprague-Dawley rats were randomly assigned into 3 groups: sham, MCAO and exercise. The middle cerebral artery occlusion (MCAO) and exercise groups received MCAO surgery and the sham group a sham operation. The exercise group also underwent treadmill exercise after the surgery. These groups were studied after 4 and 7 days to evaluate behavioral performance using a modified neurological severity score (mNSS), and infarct conditions using 2,3,5-triphenyl tetrazolium chloride. Quantitative real-time polymerase chain reaction (qRT-PCR) and Luminex was employed to determine the expressions of markers of microglia phenotypes. Western blotting was employed to identify the phosphorylation levels of Janus kinase1 (JAK1) and signal transducer and activator of transcription 6 (STAT6). Immunofluorescence was conducted to identify microglia phenotypes. Results: Treadmill exercise was found to improve neurobehavioral outcomes, mainly motor and balance functions, reduce infarct volumes and significantly increase interleukin-4 (IL-4) expression. In addition, treadmill exercise inhibited M1 microglia and promoted M2 microglia activation as evidenced by decreased M1 and increased M2 markers. Furthermore, an obvious increase in p-JAK1 and p-STAT6 was observed in the exercise group. Conclusions: Treadmill exercise ameliorates cerebral ischemia-reperfusion injury by enhancing IL-4 expression to promote M2 microglia polarization, possibly via the JAK1-STAT6 pathway.

Pro-inflammatory polarization primes Macrophages to transition into a distinct M2-like phenotype in response to IL-4

Tissue repair is largely regulated by diverse Mϕ populations whose functions are timing- and context-dependent. The early phase of healing is dominated by pro-inflammatory Mϕs, also known as M1, followed by the emergence of a distinct and diverse population that is collectively referred to as M2. The extent of the diversity of the M2 population is unknown. M2 Mϕs may originate directly from circulating monocytes or from phenotypic switching of pre-existing M1 Mϕs within the site of injury. The differences between these groups are poorly understood, but have major implications for understanding and treating pathologies characterized by deficient M2 activation, such as chronic wounds, which also exhibit diminished M1 Mϕ behavior. This study investigated the influence of prior M1 activation on human Mϕ polarization to an M2 phenotype in response to IL-4 treatment in vitro. Compared to unactivated (M0) Mϕs, M1 Mϕs up-regulated several receptors that promote the M2 phenotype, including the primary receptor for IL-4. M1 Mϕs also up-regulated M2 markers in response to lower doses of IL-4, including doses as low as 10 pg/mL, and accelerated STAT6 phosphorylation. However, M1 activation appeared to also change the Mϕ response to treatment with IL-4, generating an M2-like phenotype with a distinct gene and protein expression signature compared to M2 Mϕs prepared directly from M0 Mϕs. Functionally, compared to M0-derived M2 Mϕs, M1-derived M2 Mϕs demonstrated increased migratory response to SDF-1α, and conditioned media from these Mϕs promoted increased migration of endothelial cells in transwell assays, although other common Mϕ-associated functions such as phagocytosis were not affected by prior polarization state. In summary, M1 polarization appears to prime Mϕs to transition into a distinct M2 phenotype in response to IL4, which leads to increased expression of some genes and proteins and decreased expression of others, as well as functional differences. Together, these findings indicate the importance of prior M1 activation in regulating subsequent M2 behavior, and suggest that correcting M1 behavior may be a therapeutic target in dysfunctional M2 activation.

Follicular dendritic cells restrict interleukin-4 availability in germinal centers and foster memory B cell generation

B cells within germinal centers (GCs) enter cycles of antibody affinity maturation or exit the GC as memory cells or plasma cells. Here, we examined the contribution of interleukin (IL)-4 on B cell fate decisions in the GC. Single-cell RNA-sequencing identified a subset of light zone GC B cells expressing high IL-4 receptor-a (IL4Ra) and CD23 and lacking a Myc-associated signature. These cells could differentiate into pre-memory cells. B cell-specific deletion of IL4Ra or STAT6 favored the pre-memory cell trajectory, and provision of exogenous IL-4 in a wild-type context reduced pre-memory cell frequencies. IL-4 acted during antigen-specific interactions but also influenced bystander cells. Deletion of IL4Ra from follicular dendritic cells (FDCs) increased the availability of IL-4 in the GC, impaired the selection of affinity-matured B cells, and reduced memory cell generation. We propose that GC FDCs establish a niche that limits bystander IL-4 activity, focusing IL-4 action on B cells undergoing selection and enhancing memory cell differentiation.

Microglial Phenotypic Transition: Signaling Pathways and Influencing Modulators Involved in Regulation in Central Nervous System Diseases

Microglia are macrophages that reside in the central nervous system (CNS) and belong to the innate immune system. Moreover, they are crucially involved in CNS development, maturation, and aging; further, they are closely associated with neurons. In normal conditions, microglia remain in a static state. Upon trauma or lesion occurrence, microglia can be activated and subsequently polarized into the pro-inflammatory or anti-inflammatory phenotype. The phenotypic transition is regulated by numerous modulators. This review focus on the literature regarding the modulators and signaling pathways involved in regulating the microglial phenotypic transition, which are rarely mentioned in other reviews. Hence, this review provides molecular insights into the microglial phenotypic transition, which could be a potential therapeutic target for neuroinflammation.

SIRPα sequesters SHP-2 to promote IL-4 and IL-13 signaling and the alternative activation of macrophages

[Figure: see text].

IL13 Acts Directly on Gastric Epithelial Cells to Promote Metaplasia Development During Chronic Gastritis

BACKGROUND & AIMS

It is well established that chronic inflammation promotes gastric cancer-associated metaplasia, but little is known regarding the mechanisms by which immune cells and cytokines regulate metaplastic cellular changes. The goals of this study were to identify interleukin 13 (IL13)-producing immune cells, determine the gastric epithelial cell response(s) to IL13, and establish the role(s) of IL13 in metaplasia development.

METHODS

Experiments used an established mouse model of autoimmune gastritis (TxA23), TxA23×Il4ra-/- mice, which develop gastritis but do not express the IL4/IL13-receptor subunit IL4Rα, and TxA23×Il13-Yfp mice, which express yellow fluorescent protein in IL13-producing cells. Flow cytometry was used to measure IL13 secretion and identify IL13-producing immune cells. Mouse and human gastric organoids were cultured with IL13 to determine epithelial cell response(s) to IL13. Single-cell RNA sequencing was performed on gastric epithelial cells from healthy and inflamed mouse stomachs. Mice with gastritis were administered IL13-neutralizing antibodies and stomachs were analyzed by histopathology and immunofluorescence.

RESULTS

We identified 6 unique subsets of IL13-producing immune cells in the inflamed stomach. Organoid cultures showed that IL13 acts directly on gastric epithelium to induce a metaplastic phenotype. IL4Rα-deficient mice did not progress to metaplasia. Single-cell RNA sequencing determined that gastric epithelial cells from IL4Rα-deficient mice up-regulated inflammatory genes but failed to up-regulate metaplasia-associated transcripts. Neutralization of IL13 significantly reduced and reversed metaplasia development in mice with gastritis.

CONCLUSIONS

IL13 is made by a variety of immune cell subsets during chronic gastritis and promotes gastric cancer-associated metaplastic epithelial cell changes. Neutralization of IL13 reduces metaplasia severity during chronic gastritis.

Novel pathogenesis of atopic dermatitis from the view of cytokines in mice and humans

Type 2 immunity and inflammation underlie allergic skin disorders, such as atopic dermatitis (AD). In type 2 inflammation, IL-4, IL-13, and IL-5, which are signature type 2 cytokines, are mainly produced by type 2 helper T (Th2) cells and form the characteristic features of AD. Epithelial cell-derived cytokines such as IL-25, IL-33, and TSLP initiate type 2 inflammation by modulating various cells, including group 2 innate lymphoid cells. Moreover, IL-31, a newly identified type 2 cytokine produced mainly by Th2 cells, induces pruritus by acting on sensory neurons in the skin. Based on both basic and clinical findings, several biologics targeting Th2 cytokines have been developed and exhibited significant efficacy as therapeutic reagents for AD. We have summarized the roles of each cytokine (IL-4, 5, 13, 25, 31, and 33, and TSLP) in the development of type 2 inflammation, especially AD, from the view of basic studies in mice and clinical trials/observation in humans.

IL-13 is a driver of COVID-19 severity

Immune dysregulation is characteristic of the more severe stages of SARS-CoV-2 infection. Understanding the mechanisms by which the immune system contributes to COVID-19 severity may open new avenues to treatment. Here, we report that elevated IL-13 was associated with the need for mechanical ventilation in 2 independent patient cohorts. In addition, patients who acquired COVID-19 while prescribed Dupilumab, a mAb that blocks IL-13 and IL-4 signaling, had less severe disease. In SARS-CoV-2-infected mice, IL-13 neutralization reduced death and disease severity without affecting viral load, demonstrating an immunopathogenic role for this cytokine. Following anti-IL-13 treatment in infected mice, hyaluronan synthase 1 (Has1) was the most downregulated gene, and accumulation of the hyaluronan (HA) polysaccharide was decreased in the lung. In patients with COVID-19, HA was increased in the lungs and plasma. Blockade of the HA receptor, CD44, reduced mortality in infected mice, supporting the importance of HA as a pathogenic mediator. Finally, HA was directly induced in the lungs of mice by administration of IL-13, indicating a new role for IL-13 in lung disease. Understanding the role of IL-13 and HA has important implications for therapy of COVID-19 and, potentially, other pulmonary diseases. IL-13 levels were elevated in patients with severe COVID-19. In a mouse model of the disease, IL-13 neutralization reduced the disease and decreased lung HA deposition. Administration of IL-13-induced HA in the lung. Blockade of the HA receptor CD44 prevented mortality, highlighting a potentially novel mechanism for IL-13-mediated HA synthesis in pulmonary pathology.

Targeting and pharmacology of an anti-IL13Rα2 antibody and antibody-drug conjugate in a melanoma xenograft model

IL13Rα2 is a cell surface tumor antigen that is overexpressed in multiple tumor types. Here, we studied biodistribution and targeting potential of an anti-IL13Rα2 antibody (Ab) and anti-tumor activity of anti-IL13Rα2-antibody-drug conjugate (ADC). The anti-IL13Rα2 Ab was labeled with fluorophore AF680 or radioisotope ⁸⁹Zr for in vivo tracking using fluorescence molecular tomography (FMT) or positron emission tomography (PET) imaging, respectively. Both imaging modalities showed that the tumor was the major uptake site for anti-IL13Rα2-Ab, with peak uptake of 5–8% ID and 10% ID/g as quantified from FMT and PET, respectively. Pharmacological in vivo competition with excess of unlabeled anti-IL13Rα2-Ab significantly reduced the tumor uptake, indicative of antigen-specific tumor accumulation. Further, FMT imaging demonstrated similar biodistribution and pharmacokinetic profiles of an auristatin-conjugated anti-IL13Rα2-ADC as compared to the parental Ab. Finally, the anti-IL13Rα2-ADC exhibited a dose-dependent anti-tumor effect on A375 xenografts, with 90% complete responders at a dose of 3 mg/kg. Taken together, both FMT and PET showed a favorable biodistribution profile for anti-IL13Rα2-Ab/ADC, along with antigen-specific tumor targeting and excellent therapeutic efficacy in the A375 xenograft model. This work shows the great potential of this anti-IL13Rα2-ADC as a targeted anti-cancer agent.

Anti-Inflammatory Therapeutic Approaches to Prevent or Delay Post-Traumatic Osteoarthritis (PTOA) of the Knee Joint with a Focus on Sustained Delivery Approaches

Inflammation plays a central role in the pathogenesis of knee PTOA after knee trauma. While a comprehensive therapy capable of preventing or delaying post-traumatic osteoarthritis (PTOA) progression after knee joint injury does not yet clinically exist, current literature suggests that certain aspects of early post-traumatic pathology of the knee joint may be prevented or delayed by anti-inflammatory therapeutic interventions. We discuss multifaceted therapeutic approaches that may be capable of effectively reducing the continuous cycle of inflammation and concomitant processes that lead to cartilage degradation as well as those that can simultaneously promote intrinsic repair processes. Within this context, we focus on early disease prevention, the optimal timeframe of treatment and possible long-lasting sustained delivery local modes of treatments that could prevent knee joint-associated PTOA symptoms. Specifically, we identify anti-inflammatory candidates that are not only anti-inflammatory but also anti-degenerative, anti-apoptotic and pro-regenerative.

The Implications of Pruritogens in the Pathogenesis of Atopic Dermatitis

Atopic dermatitis (AD) is a prototypic inflammatory disease that presents with intense itching. The pathophysiology of AD is multifactorial, involving environmental factors, genetic susceptibility, skin barrier function, and immune responses. A recent understanding of pruritus transmission provides more information about the role of pruritogens in the pathogenesis of AD. There is evidence that pruritogens are not only responsible for eliciting pruritus, but also interact with immune cells and act as inflammatory mediators, which exacerbate the severity of AD. In this review, we discuss the interaction between pruritogens and inflammatory molecules and summarize the targeted therapies for AD.

IL-13Rα2 Is a Biomarker of Diagnosis and Therapeutic Response in Human Pancreatic Cancer

IL-13Rα2 is a high-affinity binding protein for its ligand IL-13 and a cancer-testis antigen as it is expressed in the testis. IL-13Rα2 is highly expressed in various cancers, including pancreatic cancer, and consists of three domains: extracellular, transmembrane, and cytoplasmic. The extracellular domain binds to the ligand to form a biologically active complex, which initiates signaling through AP-1 and other pathways. IL-13Rα2 is also expressed in diseased cells such as fibroblasts that are involved in various inflammatory diseases, including cancer. We have reported that IL-13Rα2 is a prognostic biomarker for malignant glioma, adrenocortical cancer, and pancreatic cancer. In pancreatic cancer, a small sample of tissue could be examined for the expression of IL-13Rα2 by using the endoscopic ultrasound-fine needle aspiration technique (EUS-FNA). In addition, a peptide-based targeted approach using Pep-1L peptide could be used to study the biodistribution and whole-body cancer imaging for the screening of pancreatic cancer in suspected subjects.

Orthosiphon stamineus Proteins Alleviate Hydrogen Peroxide Stress in SH-SY5Y Cells

The neuroprotective potential of Orthosiphon stamineus leaf proteins (OSLPs) has never been evaluated in SH-SY5Y cells challenged by hydrogen peroxide (H₂O₂). This work thus aims to elucidate OSLP neuroprotective potential in alleviating H₂O₂ stress. OSLPs at varying concentrations were evaluated for cytotoxicity (24 and 48 h) and neuroprotective potential in H₂O₂-induced SH-SY5Y cells (24 h). The protective mechanism of H₂O₂-induced SH-SY5Y cells was also explored via mass-spectrometry-based label-free quantitative proteomics (LFQ) and bioinformatics. OSLPs (25, 50, 125, 250, 500, and 1000 µg/mL; 24 and 48 h) were found to be safe. Pre-treatments with OSLP doses (250, 500, and 1000 µg/mL, 24 h) significantly increased the survival of SH-SY5Y cells in a concentration-dependent manner and improved cell architecture—pyramidal-shaped cells, reduced clumping and shrinkage, with apparent neurite formations. OSLP pre-treatment (1000 µg/mL, 24 h) lowered the expressions of two major heat shock proteins, HSPA8 (heat shock protein family A (Hsp70) member 8) and HSP90AA1 (heat shock protein 90), which promote cellular stress signaling under stress conditions. OSLP is, therefore, suggested to be anti-inflammatory by modulating the “signaling of interleukin-4 and interleukin-13” pathway as the predominant mechanism in addition to regulating the “attenuation phase” and “HSP90 chaperone cycle for steroid hormone receptors” pathways to counteract heat shock protein (HSP)-induced damage under stress conditions.

Tumor suppressor p53 regulates intestinal type 2 immunity

The role of p53 in tumor suppression has been extensively studied and well-established. However, the role of p53 in parasitic infections and the intestinal type 2 immunity is unclear. Here, we report that p53 is crucial for intestinal type 2 immunity in response to the infection of parasites, such as Tritrichomonas muris and Nippostrongylus brasiliensis. Mechanistically, p53 plays a critical role in the activation of the tuft cell-IL-25-type 2 innate lymphoid cell circuit, partly via transcriptional regulation of Lrmp in tuft cells. Lrmp modulates Ca2+ influx and IL-25 release, which are critical triggers of type 2 innate lymphoid cell response. Our results thus reveal a previously unrecognized function of p53 in regulating intestinal type 2 immunity to protect against parasitic infections, highlighting the role of p53 as a guardian of immune integrity.

Recent developments in the pathogenesis of pruritus in bullous pemphigoid

Bullous pemphigoid (BP) is a common autoimmune bullous disease which mainly affects the elderly. The incidence of BP is gradually increasing and associated with high mortality. This disease is clinically characterized by intensely pruritic and widespread bullous lesions. Alternative therapy options for pruritus in patients with BP are limited primarily because pathophysiological mechanisms of itching in BP are still unclear. This review aims to explain crucial concepts of the pathogenesis of pruritus in BP. Vital findings in recent years will be summarized, and cofactors of the pathogenesis of pruritus will be discussed in detail. We will summarize knowledge on pathogenic factors in the immunologic level conducing to skin pruritus in BP.

STAT3 determines IL-4 signalling outcomes in naïve T cells

IL-4 production is associated with low-avidity, poorly cytotoxic T cell induction that contributes to viral immune evasion and the failure of T cell-based vaccines. Yet, the precise mechanisms that regulate IL-4 signalling in T cells remain elusive. Mounting evidence indicates that cells can dynamically alter their IL-4/IL-13 receptor signature to modulate downstream immune outcomes upon pathogen encounter. Here, we describe how naïve (CD62L⁺CD44^lo-mid) CD4 and CD8 T cells distinctly engage both STAT6 and STAT3 in response to IL-4. We further show that IL-4R⍺ expression is both time- and IL-4 concentration-dependent. Remarkably, our findings reveal that STAT3 inhibition can ablate IL-4R⍺ and affect transcriptional expression of other Stat and Jak family members. By extension, the loss of STAT3 lead to aberrant STAT6 phosphorylation, revealing an inter-regulatory relationship between the two transcription factors. Moreover, IL-4 stimulation down-regulated TGF-β1 and IFN-γR1 expression on naïve T cells, possibly signifying the broad regulatory implications of IL-4 in conditioning lineage commitment decisions during early infection. Surprisingly, naïve T cells were unresponsive to IL-13 stimulation, unlike dendritic cells. Collectively, these findings could be exploited to inform more efficacious vaccines, as well as design treatments against IL-4/IL-13-associated disease conditions.

Generation of a chemical genetic model for JAK3

Janus Kinases (JAKs) have emerged as an important drug target for the treatment of a number of immune disorders due to the central role that they play in cytokine signalling. 4 isoforms of JAKs exist in mammalian cells and the ideal isoform profile of a JAK inhibitor has been the subject of much debate. JAK3 has been proposed as an ideal target due to its expression being largely restricted to the immune system and its requirement for signalling by cytokine receptors using the common γ-chain. Unlike other JAKs, JAK3 possesses a cysteine in its ATP binding pocket and this has allowed the design of isoform selective covalent JAK3 inhibitors targeting this residue. We report here that mutating this cysteine to serine does not prevent JAK3 catalytic activity but does greatly increase the IC50 for covalent JAK3 inhibitors. Mice with a Cys905Ser knockin mutation in the endogenous JAK3 gene are viable and show no apparent welfare issues. Cells from these mice show normal STAT phosphorylation in response to JAK3 dependent cytokines but are resistant to the effects of covalent JAK3 inhibitors. These mice therefore provide a chemical-genetic model to study JAK3 function.

Anaphylaxis: Focus on Transcription Factor Activity

Anaphylaxis is a severe allergic reaction, rapid in onset, and can lead to fatal consequences if not promptly treated. The incidence of anaphylaxis has risen at an alarming rate in past decades and continues to rise. Therefore, there is a general interest in understanding the molecular mechanism that leads to an exacerbated response. The main effector cells are mast cells, commonly triggered by stimuli that involve the IgE-dependent or IgE-independent pathway. These signaling pathways converge in the release of proinflammatory mediators, such as histamine, tryptases, prostaglandins, etc., in minutes. The action and cell targets of these proinflammatory mediators are linked to the pathophysiologic consequences observed in this severe allergic reaction. While many molecules are involved in cellular regulation, the expression and regulation of transcription factors involved in the synthesis of proinflammatory mediators and secretory granule homeostasis are of special interest, due to their ability to control gene expression and change phenotype, and they may be key in the severity of the entire reaction. In this review, we will describe our current understanding of the pathophysiology of human anaphylaxis, focusing on the transcription factors' contributions to this systemic hypersensitivity reaction. Host mutation in transcription factor expression, or deregulation of their activity in an anaphylaxis context, will be updated. So far, the risk of anaphylaxis is unpredictable thus, increasing our knowledge of the molecular mechanism that leads and regulates mast cell activity will enable us to improve our understanding of how anaphylaxis can be prevented or treated.

IL-13Rα2 Regulates the IL-13/IFN-γ Balance during Innate Lymphoid Cell and Dendritic Cell Responses to Pox Viral Vector-Based Vaccination

We have shown that manipulation of IL-13 and STAT6 signaling at the vaccination site can lead to different innate lymphoid cell (ILC)/dendritic cell (DC) recruitment, resulting in high avidity/poly-functional T cells and effective antibody differentiation. Here we show that permanent versus transient blockage of IL-13 and STAT6 at the vaccination site can lead to unique ILC-derived IL-13 and IFN-γ profiles, and differential IL-13Rα2, type I and II IL-4 receptor regulation on ILC. Specifically, STAT6-/- BALB/c mice given fowl pox virus (FPV) expressing HIV antigens induced elevated ST2/IL-33R+ ILC2-derived IL-13 and reduced NKp46+/- ILC1/ILC3-derived IFN-γ expression, whilst the opposite (reduced IL-13 and elevated IFN-γ expression) was observed during transient inhibition of STAT6 signaling in wild type BALB/c mice given FPV-HIV-IL-4R antagonist vaccination. Interestingly, disruption/inhibition of STAT6 signaling considerably impacted IL-13Rα2 expression by ST2/IL-33R+ ILC2 and NKp46- ILC1/ILC3, unlike direct IL-13 inhibition. Consistently with our previous findings, this further indicated that inhibition of STAT6 most likely promoted IL-13 regulation via IL-13Rα2. Moreover, the elevated ST2/IL-33R+ IL-13Rα2+ lung ILC2, 24 h post FPV-HIV-IL-4R antagonist vaccination was also suggestive of an autocrine regulation of ILC2-derived IL-13 and IL-13Rα2, under certain conditions. Knowing that IL-13 can modulate IFN-γ expression, the elevated expression of IFN-γR on lung ST2/IL-33R+ ILC2 provoked the notion that there could also be inter-regulation of lung ILC2-derived IL-13 and NKp46- ILC1/ILC3-derived IFN-γ via their respective receptors (IFN-γR and IL-13Rα2) at the lung mucosae early stages of vaccination. Intriguingly, under different IL-13 conditions differential regulation of IL-13/IL-13Rα2 on lung DC was also observed. Collectively these findings further substantiated that IL-13 is the master regulator of, not only DC, but also different ILC subsets at early stages of viral vector vaccination, and responsible for shaping the downstream adaptive immune outcomes. Thus, thoughtful selection of vaccine strategies/adjuvants that can manipulate IL-13Rα2, and STAT6 signaling at the ILC/DC level may prove useful in designing more efficacious vaccines against different/chronic pathogens.

Selective IL-13 inhibitors for the treatment of atopic dermatitis

Background

Atopic dermatitis (AD) is one of the most common chronic inflammatory skin diseases worldwide. AD pathogenesis is multifactorial, involving environmental and genetic factors. IL-13 stands out as one of the main cytokines in the pathophysiology of AD. Currently, dupilumab, which targets both IL-4 and IL-13 signalling, is the only biologic agent approved for the treatment of moderate-to-severe AD. New targeted biologic therapies are being developed, such as lebrikizumab and tralokinumab, two selective IL-13 inhibitors. This article reviews the role of IL-13 in AD and the most recent data on lebrikizumab and tralokinumab.

Methods

A narrative review of the literature was written after retrieving relevant articles in the PubMed database (up until December 2020) using the following keywords present in the title, abstract or body: atopic dermatitis; interleukin 13; IL-13; tralokinumab; lebrikizumab, biologic therapy.

Discussion

A phase IIb trial showed that all three dosing regimens evaluated (lebrikizumab 125 mg every 4 weeks (Q4W), 250 mg Q4W or 250 mg every 2 weeks) achieved rapid and dose-dependent efficacy concerning the signs and symptoms of AD, with a statistically significant improvement, at week 16. Tralokinumab was studied in three phase III clinical trials and reached its primary endpoints at week 16 (ECZTRA 1 and 2 in monotherapy and ECZTRA 3 with concomitant topical corticosteroids), with response maintained over time. Both lebrikizumab and tralokinumab exhibited good safety profiles in AD trials, with adverse effects usually being comparable between the control and treatment groups.

Conclusion

The evidence supports the hypothesis that selective antagonism of IL-13 is sufficient to control AD, providing an improvement in the patient’s quality of life. Therefore, the development of lebrikizumab and tralokinumab represents a new and exciting phase in the management of AD.

Targeting Certain Interleukins as Novel Treatment Options for Liver Fibrosis

The liver is a major metabolic organ and an immunologically complex organ. It produces and uses many substances such as acute phase proteins, cytokines, chemokines, and complementary components to maintain the balance between immunity and tolerance. Interleukins are important immune control cytokines, that are produced by many body cells. In liver injury, interleukins are produced in large amount by various cell types, and act as pro-inflammatory (e.g. interleukin (IL)-6, IL-13, IL-17, and IL-33) as well as anti-inflammatory (e.g. IL-10) functions in hepatic cells. Recently, interleukins are regarded as interesting therapeutic targets for the treatment of liver fibrosis patients. Hepatic cells such as hepatocytes, hepatic stellate cells, and hepatic macrophages are involved to the initiation, perpetuation, and resolution of fibrosis. The understanding of the role of interleukins in such cells provides opportunity for the development of therapeutic target drugs. This paper aims to understand the functional roles of interleukins in hepatic and immune cells when the liver is damaged, and suggests the possibility of interleukins as a new treatment target in liver fibrosis.

IL-13 is a driver of COVID-19 severity

Immune dysregulation is characteristic of the more severe stages of SARS-CoV-2 infection. Understanding the mechanisms by which the immune system contributes to COVID-19 severity may open new avenues to treatment. Here we report that elevated interleukin-13 (IL-13) was associated with the need for mechanical ventilation in two independent patient cohorts. In addition, patients who acquired COVID-19 while prescribed Dupilumab had less severe disease. In SARS-CoV-2 infected mice, IL-13 neutralization reduced death and disease severity without affecting viral load, demonstrating an immunopathogenic role for this cytokine. Following anti-IL-13 treatment in infected mice, in the lung, hyaluronan synthase 1 (Has1) was the most downregulated gene and hyaluronan accumulation was decreased. Blockade of the hyaluronan receptor, CD44, reduced mortality in infected mice, supporting the importance of hyaluronan as a pathogenic mediator, and indicating a new role for IL-13 in lung disease. Understanding the role of IL-13 and hyaluronan has important implications for therapy of COVID-19 and potentially other pulmonary diseases.

STAT6 Signaling Mediates PPARγ Activation and Resolution of Acute Sterile Inflammation in Mice

The signal transducer and activator of transcription 6 (STAT6) transcription factor promotes activation of the peroxisome proliferator-activated receptor gamma (PPARγ) pathway in macrophages. Little is known about the effect of proximal signal transduction leading to PPARγ activation for the resolution of acute inflammation. Here, we studied the role of STAT6 signaling in PPARγ activation and the resolution of acute sterile inflammation in a murine model of zymosan-induced peritonitis. First, we showed that STAT6 is aberrantly activated in peritoneal macrophages after zymosan injection. Utilizing STAT6^−/− and wild-type (WT) mice, we found that STAT6 deficiency further enhanced zymosan-induced proinflammatory cytokines, such as tumor necrosis factor-α, interleukin (IL)-6, and macrophage inflammatory protein-2 in peritoneal lavage fluid (PLF) and serum, neutrophil numbers and total protein amount in PLF, but reduced proresolving molecules, such as IL-10 and hepatocyte growth factor, in PLF. The peritoneal macrophages and spleens of STAT6^−/− mice exhibited lower mRNA and protein levels of PPARγ and its target molecules over the course of inflammation than those of WT mice. The deficiency of STAT6 was shown to impair efferocytosis by peritoneal macrophages. Taken together, these results suggest that enhanced STAT6 signaling results in PPARγ-mediated macrophage programming, contributing to increased efferocytosis and inflammation resolution.

Early immune response in large yellow croaker (Larimichthys crocea) after immunization with oral vaccine

Mesoporous silica nanoparticles (MSNs) have been used in the field of biomedicine as antigen carriers and adjuvants for protective antigens. In the present study, an oral nanovaccine against Vibrio alginolyticus was prepared employing MSNs as carriers. The uptake of the dihydrolipoamide dehydrogenase (DLDH) antigens in the intestine of large yellow croaker was evaluated using an immunohistochemistry assay. Additionally, the effects of the nanovaccine on the early immune response in large yellow croaker were investigated via oral vaccination. The presence of the antigens was detected in the mucosa and lamina propria of the foregut, midgut, and hindgut of large yellow croaker at 3 h following oral immunization. The expression levels of cytokines (i.e., lysozyme, IFN-γ, IFITM, TNF-α, IL-1β, IL-2, IL-4, IL-10, and IL-13) in the intestine, spleen, and head kidney tissues of large yellow croaker before and after the immune challenge were determined via RT-qPCR assay. The obtained results revealed that the expression levels of lysozyme, IFN-γ, IFITM, TNF-α, IL-1β, IL-2, IL-4, IL-10, and IL-13 in the intestine and head kidney of the vaccinated large yellow croaker, as well as the expression of lysozyme, IL-1β, and IL-10 in the spleen, exhibited time-dependent oscillation regulation patterns. Notably, the nanovaccine immunization could induce early (6 h) and high expression of IFN-γ in the spleen and kidney tissues after the bacterial infection. The current study supplements the available data on the early immune response to fish nanovaccines. It also provides a valuable theoretical basis for the future development of large yellow croaker oral vaccines.

A tale of two fish: Comparative transcriptomics of resistant and susceptible steelhead following exposure to Ceratonova shasta highlights differences in parasite recognition

Diseases caused by myxozoan parasites represent a significant threat to the health of salmonids in both the wild and aquaculture setting, and there are no effective therapeutants for their control. The myxozoan Ceratonova shasta is an intestinal parasite of salmonids that causes severe enteronecrosis and mortality. Most fish populations appear genetically fixed as resistant or susceptible to the parasite, offering an attractive model system for studying the immune response to myxozoans. We hypothesized that early recognition of the parasite is a critical factor driving resistance and that susceptible fish would have a delayed immune response. RNA-seq was used to identify genes that were differentially expressed in the gills and intestine during the early stages of C. shasta infection in both resistant and susceptible steelhead (Oncorhynchus mykiss). This revealed a downregulation of genes involved in the IFN-γ signaling pathway in the gills of both phenotypes. Despite this, resistant fish quickly contained the infection and several immune genes, including two innate immune receptors were upregulated. Susceptible fish, on the other hand, failed to control parasite proliferation and had no discernible immune response to the parasite, including a near-complete lack of differential gene expression in the intestine. Further sequencing of intestinal samples from susceptible fish during the middle and late stages of infection showed a vigorous yet ineffective immune response driven by IFN-γ, and massive differential expression of genes involved in cell adhesion and the extracellular matrix, which coincided with the breakdown of the intestinal structure. Our results suggest that the parasite may be suppressing the host’s immune system during the initial invasion, and that susceptible fish are unable to recognize the parasite invading the intestine or mount an effective immune response. These findings improve our understanding of myxozoan-host interactions while providing a set of putative resistance markers for future studies.

The role of IL-4 gene polymorphism in HCV-related hepatocellular carcinoma in Egyptian patients

Background

Interleukin-4 (IL-4), a pleiotropic anti-inflammatory cytokine, is produced mainly by activated T helper 2 (Th2). Hepatocellular carcinoma (HCC) is a typical inflammation-related cancer. Alterations influencing IL-4 expression may disturb immune response and may be associated with HCC risk. We aimed to verify role of IL4 gene polymorphism (IL-4-589C/T (rs2243250)) in HCV-related hepatocellular carcinoma in Egyptian patients. IL-4-589C/T (rs2243250) polymorphism was examined in 50 patients with HCC on top of HCV, 40 patients with HCV-induced liver cirrhosis, and 30 healthy controls using the polymerase chain reaction- restriction fragment length polymorphism method.

Results

Overall IL-4 gene polymorphism (IL-4-589C/T (rs2243250)) showed significant difference between hepatocellular carcinoma group versus liver cirrhosis and healthy control groups. TT homozygous genotype was more prevalent in HCC group (24%) versus (5%) in liver cirrhosis and (3.3%) in control. TT homozygous genotype had 10 times more risk of hepatocellular carcinoma versus healthy control group and 6.33 times more risk versus cirrhotic patients group (p value = 0.018 and 0.016 respectively).

Conclusion

IL-4-589C/T (rs2243250) polymorphism, TT homozygous genetic model, may be a risk factor in HCV-related HCC in Egyptian patients.