IL-6 prevents Th2 cell polarization by promoting SOCS3-dependent suppression of IL-2 signaling

Genetically proxied IL-6 receptor inhibition is associated with increased risk of atopic dermatitis

BACKGROUND

Dermatitis has been reported after initiation of IL-6 receptor (IL-6R) inhibitors (IL-6Ri), while genetic association studies of atopic dermatitis (AD) have implicated IL-6R pathway signaling. However, causality remains unclear. As the indications for IL-6Ri expand, so do the clinical importance of determining whether there is mechanistic evidence linking it to AD.

OBJECTIVE

Our aim was to examine the association between IL-6Ri and risk of AD.

METHODS

To genetically mimic IL-6Ri, we selected single-nucleotide polymorphisms within or near the IL6R gene associated with C-reactive protein at genome-wide significance among 343,524 individuals. Genetic data were obtained from 10,788 individuals with AD and 30,047 controls of European ancestry. We used inverse variance-weighted and pleiotropy-robust methods and examined genetic confounding using colocalization. Analyses were replicated by using 13,473 Finnish and 2,385 East Asian individuals with AD. The results from 3 independent analyses were pooled by meta-analysis.

RESULTS

Genetically proxied IL-6Ri was associated with increased risk of AD (odds ratio [OR] = 1.78 per 4.4-mg/L reduction in C-reactive protein level [95% CI = 1.28-2.48] [P = 6.5 × 10-4]). The results were replicated using Finnish outcome data (OR = 2.07 [95% CI = 1.58-2.72] [P = 1.57 × 10-7]) and Eastern Asian data (OR = 1.68 [95% CI = 1.12-2.54] [P = .013]). Meta-analysis of 3 independent populations (OR = 1.89 [95% CI = 1.57-2.28] [P = 2.68 × 10-11]) showed no evidence of heterogeneity (P = .65). We found no statistical evidence for pleiotropy or genetic confounding.

CONCLUSION

This genetic investigation provides consistent evidence (across independent multiancestry populations) that IL-6R signaling is causally implicated in AD susceptibility. Clinicians should remain vigilant for adverse effects resembling AD when using IL-6R inhibitors for immune-mediated inflammatory diseases.

Cang-ai volatile oil alleviates nasal inflammation via Th1/Th2 cell imbalance regulation in a rat model of ovalbumin-induced allergic rhinitis

We previously revealed that Cang-ai volatile oil (CAVO) regulates T-cell activity, enhancing the immune response in people with chronic respiratory diseases. However, the effects of CAVO on allergic rhinitis (AR) have not been investigated. Herein, we established an ovalbumin (OVA)-induced AR rat model to determine these effects. Sprague-Dawley (SD) rats were exposed to OVA for 3 weeks. CAVO or loratadine (positive control) was given orally once daily for 2 weeks to OVA-exposed rats. Behavior modeling nasal allergies was observed. Nasal mucosa, serum, and spleen samples of AR rats were analyzed. CAVO treatment significantly reduced the number of nose rubs and sneezes, and ameliorated several hallmarks of nasal mucosa tissue remodeling: inflammation, eosinophilic infiltration, goblet cell metaplasia, and mast cell hyperplasia. CAVO administration markedly upregulated expressions of interferon-γ, interleukin (IL)-2, and IL-12, and downregulated expressions of serum tumor necrosis factor-α, IL-4, IL-5, IL-6, IL-13, immunoglobulin-E, and histamine. CAVO therapy also increased production of IFN-γ and T-helper type 1 (Th1)-specific T-box transcription factor (T-bet) of the cluster of differentiation-4+ T-cells in splenic lymphocytes, and protein and mRNA expressions of T-bet in nasal mucosa. In contrast, levels of the Th2 cytokine IL-4 and Th2-specific transcription factor GATA binding protein-3 were suppressed by CAVO. These cumulative findings demonstrate that CAVO therapy can alleviate AR by regulating the balance between Th1 and Th2 cells.

Human germline gain-of-function in STAT6: from severe allergic disease to lymphoma and beyond

Signal transducer and activator of transcription (STAT)-6 is a transcription factor central to pro-allergic immune responses, although the function of human STAT6 at the whole-organism level has long remained unknown. Germline heterozygous gain-of-function (GOF) rare variants in STAT6 have been recently recognized to cause a broad and severe clinical phenotype of early-onset, multi-system allergic disease. Here, we provide an overview of the clinical presentation of STAT6-GOF disease, discussing how dysregulation of the STAT6 pathway causes severe allergic disease, and identifying possible targeted treatment approaches. Finally, we explore the mechanistic overlap between STAT6-GOF disease and other monogenic atopic disorders, and how this group of inborn errors of immunity (IEIs) powerfully inform our fundamental understanding of common human allergic disease.

Endogenous blocking of TLR2 along with TNF-α and IL-1β ameliorates the severity of the S. aureus arthritis via modulating STAT3/SOCS3 expressions in tissue resident macrophages

In vivo studies identifying a role of TLR2 in septic arthritis models are lacking. TNF-α played as the most important proinflammatory cytokine, and connected directly to the pathogenesis of bacterial arthritis. IL-1β is another central mediator cytokine in arthritis. It is therefore reasonable to question the role of neutralization of endogenous TNF-α and IL-1β along with TLR2 and associated downstream signaling as crucial mediators in the S. aureus -induced inflammatory arthritis. In reaction to an injury or a pathogen encounter, innate immune cells serve as the initial line of defense. TLR2 mediated entry of S. aureus into macrophage cells initiates an array of inflammatory cascades. After macrophage cell gets activated at the site inflammation, they generate elevated number of cytokines which includes TNF-α, IL-1β. This cytokines signals through STAT1/STAT3 mediated pathways. Thus, aim of this study was to discover how This bone damage could be altered by altering the STAT/STAT3/SOCS3 ratio by blocking TLR2, a particular S. aureus binding site, in conjunction with the use of IL-1 and TNF- antibodies for neutralizing endogenous IL-1β and TNF-α. Additionally, the role of local macrophages in therapy of arthritis was investigated in synovial and Splenic tissue. To comprehend the inflammatory milieu within the system, ROS and other antioxidant enzymes, along with the expression of mTOR in macrophage cells, were also taken into consideration. The detrimental impact of bacterial burden on synovial joints was reduced by simultaneously inhibiting TLR2, TNF-α, and IL-1β. Lowered IFN-γ decreases its sensitivity to STAT1 and lowered IL-6 reduces STAT3 expressions. Whereas, elevated IL-10 enhances SOSC3 expression, which thereby able to limits STAT1/STAT3 inter-conversion. As a result, NF-κB activity was downregulated.

Rapid activation of IL-2 receptor signaling by CD301b+ DC-derived IL-2 dictates the outcome of helper T cell differentiation

Effector T helper (Th) cell differentiation is fundamental to functional adaptive immunity. Different subsets of dendritic cells (DCs) preferentially induce different types of Th cells, but the fate instruction mechanism for Th type 2 (Th2) differentiation remains enigmatic, as the critical DC-derived cue has not been clearly identified. Here, we show that CD301b+ DCs, a major Th2-inducing DC subset, drive Th2 differentiation through cognate interaction by 'kick-starting' IL-2 receptor signaling in CD4T cells. Mechanistically, CD40 engagement induces IL-2 production selectively from CD301b+ DCs to maximize CD25 expression in CD4 T cells, which is required specifically for the Th2 fate decision. On the other hand, CD25 in CD301b+ DCs facilitates directed action of IL-2 toward cognate CD4T cells. Furthermore, CD301b+ DC-derived IL-2 skews CD4T cells away from the T follicular helper fate. These results highlight the critical role of DC-intrinsic CD40-IL-2 axis in bifurcation of Th cell fate.

Curcumin alleviated dextran sulfate sodium-induced colitis by recovering memory Th/Tfh subset balance

BACKGROUND

Restoration of immune homeostasis by targeting the balance between memory T helper (mTh) cells and memory follicular T helper (mTfh) cells is a potential therapeutic strategy against ulcerative colitis (UC). Because of its anti-inflammatory and immunomodulatory properties, curcumin (Cur) is a promising drug for UC treatment. However, fewer studies have demonstrated whether Cur can modulate the mTh/mTfh subset balance in mice with colitis.

AIM

To explore the potential mechanism underlying Cur-mediated alleviation of colitis induced by dextran sulfate sodium (DSS) in mice by regulating the mTh and mTfh immune homeostasis.

METHODS

Balb/c mice were administered 3% and 2% DSS to establish the UC model and treated with Cur (200 mg/kg/d) by gavage on days 11-17. On the 18th d, all mice were anesthetized and euthanized, and the colonic length, colonic weight, and colonic weight index were evaluated. Histomorphological changes in the mouse colon were observed through hematoxylin-eosin staining. Levels of Th/mTh and Tfh/mTfh cell subsets in the spleen were detected through flow cytometry. Western blotting was performed to detect SOCS-1, SOCS-3, STAT3, p-STAT3, JAK1, p-JAK1, and NF-κB p65 protein expression levels in colon tissues.

RESULTS

Cur effectively mitigates DSS-induced colitis, facilitates the restoration of mouse weight and colonic length, and diminishes the colonic weight and colonic weight index. Simultaneously, it hinders ulcer development and inflammatory cell infiltration in the colonic mucous membrane. While the percentage of Th1, mTh1, Th7, mTh7, Th17, mTh17, Tfh1, mTfh1, Tfh7, mTfh7, Tfh17, and mTfh17 cells decreased after Cur treatment of the mice for 7 d, and the frequency of mTh10, Th10, mTfh10, and Tfh10 cells in the mouse spleen increased. Further studies revealed that Cur administration prominently decreased the SOCS-1, SOCS-3, STAT3, p-STAT3, JAK1, p-JAK1, and NF-κB p65 protein expression levels in the colon tissue.

CONCLUSION

Cur regulated the mTh/mTfh cell homeostasis to reduce DSS-induced colonic pathological damage, potentially by suppressing the JAK1/STAT3/SOCS signaling pathway.

Sensing of protease activity as a triggering mechanism of Th2 cell immunity and allergic disease

CD4 T-helper cell type 2 (Th2) cells mediate host defense against extracellular parasites, like helminths. However, Th2 cells also play a pivotal role in the onset and progression of allergic inflammatory diseases such as atopic dermatitis, allergic rhinitis, asthma, and food allergy. This happens when allergens, which are otherwise harmless foreign proteins, are mistakenly identified as "pathogenic." Consequently, the encounter with these allergens triggers the activation of specific Th2 cell responses, leading to the development of allergic reactions. Understanding the molecular basis of allergen sensing is vital for comprehending how Th2 cell responses are erroneously initiated in individuals with allergies. The presence of protease activity in allergens, such as house dust mites (HDM), pollen, fungi, or cockroaches, has been found to play a significant role in triggering robust Th2 cell responses. In this review, we aim to examine the significance of protease activity sensing in foreign proteins for the initiation of Th2 cell responses, highlighting how evolving a host protease sensor may contribute to detect invading helminth parasites, but conversely can also trigger unwanted reactions to protease allergens. In this context, we will explore the recognition receptors activated by proteolytic enzymes present in major allergens and their contribution to Th2-mediated allergic responses. Furthermore, we will discuss the coordinated efforts of sensory neurons and epithelial cells in detecting protease allergens, the subsequent activation of intermediary cells, including mast cells and type 2 innate lymphoid cells (ILC2s), and the ultimate integration of all signals by conventional dendritic cells (cDCs), leading to the induction of Th2 cell responses. On the other hand, the review highlights the role of monocytes in the context of protease allergen exposure and their interaction with cDCs to mitigate undesirable Th2 cell reactions. This review aims to provide insights into the innate functions and cell communications triggered by protease allergens, which can contribute to the initiation of detrimental Th2 cell responses, but also promote mechanisms to effectively suppress their development.

A model of Th2 differentiation based on polarizing cytokine repression

Conventional dendritic cells (cDCs) can integrate multiple stimuli from the environment and provide three separate outputs in terms of antigen presentation, costimulation, and cytokine production; this guides the activation, expansion, and differentiation of distinct functional T helper subsets. Accordingly, the current dogma posits that T helper cell specification requires these three signals in sequence. Data show that T helper 2 (Th2) cell differentiation requires antigen presentation and costimulation from cDCs but does not require polarizing cytokines. In this opinion article, we propose that the 'third signal' driving Th2 cell responses is, in fact, the absence of polarizing cytokines; indeed, the secretion of the latter is actively suppressed in cDCs, concomitant with acquired pro-Th2 functions.