IL-33 Deficiency Attenuates Lung Inflammation by Inducing Th17 Response and Impacting the Th17/Treg Balance in LPS-Induced ARDS Mice via Dendritic Cells

IL-33 facilitates endoplasmic reticulum stress and pyroptosis in LPS-stimulated ARDS model in vitro

BACKGROUND

Inflammatory activation of pulmonary microvascular endothelial cells (PMVECs) initiated by endoplasmic reticulum stress (ERS) contributes to acute respiratory distress syndrome (ARDS). Interleukin 33 (IL-33) has pro-inflammatory and transcriptional regulatory effects. Therefore, this study intends to investigate the effect of IL-33 on ERS and pyroptosis in the hPMVEC.

METHODS

The hPMVEC-associated ARDS cell model was induced with lipopolysaccharide (LPS) and treated with 4-PBA (ERS inhibitor), thapsigargin (ERS activator), or IL-33 neutralizing antibody. Western blot and IF staining were performed to analyze the expression of cell-cell junction-associated (Cx37, Cx40, Cx43, Occludin, and Zo-1), ERS-associated (ATF6, IRE1a, and p-Erk), and pyroptosis-associated (NLRP3, IL-1β, and IL-18) proteins. Bioinformatics identified differential expression of IL-33 in ARDS-related datasets and targets of thapsigargin.

RESULTS

IL-33 was highly expressed in serum of ARDS patients and in ARDS cohorts from multiple GEO datasets (GSE237260, GSE216635, GSE89953, GSE263867, and GSE5883), and was significantly correlated with clinical features. 4-PBA decreased permeability and IL-33 levels, and increased Cx37, Cx40 and Cx43 levels in the ARDS cell model. IL-33 neutralizing antibody effectively augmented the levels of Cx43 and Zo-1, and diminished the levels of ATF6, IRE1a, p-Erk, NLRP3, IL-1β, IL-18, ROS, and Ca2 +. The therapeutic effect of IL-33 neutralizing antibodies was reverted by thapsigargin. Moreover, the Swiss Target Prediction and Super-PRED databases obtained 140 and 122 thapsigargin targets, which had 14 intersections. These intersections were associated with immunity, inflammation, apoptosis, pyroptosis, and Ca2+ homeostasis. Notably, CASP8 and PTGS2 interacted with IL-33 in these intersections.

CONCLUSION

IL-33 promotes ERS and pyroptosis, thereby contributing to barrier damage in ARDS cell models. IL-33 is a promising therapeutic target for ARDS.

Chemical characterization of Siraitia grosvenorii granules and their efficacy and mechanism of action on PM2.5-induced acute lung injury

This study aimed to investigate the potential protective properties of a traditional Chinese medicine (TCM) herbal product, Siraitia grosvenorii granules (SGG) against PM2.5-induced lung injury, as well as their active constituents and underlying mechanisms. The chemical composition of SGG, such as wogonin (MOL000173), luteolin (MOL000006), nobiletin (MOL005828), naringenin (MOL004328), acacetin (MOL001689), were identified via ultra-high-performance liquid chromatography-Q Exactive (UHPLC-QE) Orbitrap/MS. The specific targets and pathways through which the compounds exert their effects on acute lung injury were then predicted via network pharmacology. The lung-protective effects of SGG against particulate matter (PM2.5) were investigated via in vivo experiments. Results showed that PM2.5-induced lung damage was associated with oxidative stress, suppression of PI3K/AKT/Nrf2 pathway, and increased levels of certain alarmins & cytokines in blood and bronchial alveolar lavage fluid (BALF). However, SGG reversed these changes, particularly tissue damage and oxidative stress, suggesting that lung protection is mediated by the antioxidant effect, which mitigates the release of alarmin and inflammation.

Tuberculosis in South Asia: A regional analysis of burden, progress, and future projections using the global burden of disease (1990-2021)

Background

Tuberculosis (TB) is a major public health issue in South Asia and accounts for a large share of the global TB burden. Despite global efforts to curb TB incidence and mortality, progress in South Asia has been uneven, necessitating focused regional analysis to guide effective interventions. This study aims to analyse the trends in the TB burden in South Asia from 1990 to 2021 and project future TB incidence rates up to 2031.

Methods

This study utilized data from the Global Burden of Disease (GBD) 2021 results to analyse trends in age-standardized incidence (ASIR), prevalence (ASPR), mortality (ASMR), and disability-adjusted life years (DALYs) rates (ASDR) associated with TB in South Asia from 1990 to 2021. Joinpoint regression analysis was employed to identify significant trends, whereas ARIMA models were used to project future TB incidence rates up to 2031.

Results

This study revealed significant declines in the ASIR, ASPR, ASDR, and ASMR related to TB in South Asia over the past three decades. Prominent reductions were found in Bangladesh and Bhutan, whereas India, Pakistan, and Nepal continue to bear the highest TB burdens. The ARIMA model projections indicate a continued decline in TB incidence across the region, although the extent of the decline varies by country, with less favourable trends observed in Nepal and Pakistan. The analysis also highlights tobacco use, high fasting plasma glucose, and high body mass index as significant risk factors contributing to the TB burden.

Conclusions

Substantial progress has been made in reducing the TB burden in South Asia; however, sustained and intensified efforts are needed, particularly in countries with inconsistent progress. These findings emphasize the need for targeted interventions to meet the WHO End TB Strategy (WETS) targets by 2035. Continuous monitoring and adaptive strategies will be crucial in maintaining and accelerating progress toward TB elimination in South Asia.

Progress in cytokine research for ARDS: A comprehensive review

Introduction

Acute respiratory distress syndrome (ARDS) is a critical form of acute respiratory failure characterized by diffuse alveolar damage, refractory hypoxemia, and non-cardiogenic pulmonary edema, resulting in high mortality. Dysregulated inflammation, driven by cytokines, is central to ARDS pathogenesis, progression, and prognosis.

Objective

This review synthesizes current knowledge on the role of cytokines in ARDS and evaluates their potential as therapeutic targets, offering new insights for clinical management.

Methods

A comprehensive analysis of recent studies was conducted to explore the roles of pro-inflammatory cytokines (e.g., IL-1β, IL-6, IL-8) and anti-inflammatory cytokines (e.g., IL-10, IL-22) in ARDS pathogenesis and to assess current and emerging therapies targeting these cytokines.

Results

Pro-inflammatory cytokines are crucial in initiating inflammatory responses and lung injury in early ARDS, while anti-inflammatory cytokines help regulate and resolve inflammation. Targeted therapies, such as IL-1 and IL-6 inhibitors, show potential in managing ARDS, particularly in COVID-19, but their clinical efficacy is still debated. Combination therapy strategies may enhance outcomes, but further large-scale, multicenter randomized controlled trials are required to establish their safety and efficacy.

Conclusion

Understanding cytokine regulation in ARDS could lead to innovative therapeutic approaches. Future research should focus on cytokine roles across ARDS subtypes and stages and develop biomarker-driven, individualized treatments.

Novel Therapeutic Target for ALI/ARDS: Forkhead Box Transcription Factors

ALI/ARDS can be a pulmonary manifestation of a systemic inflammatory response or a result of overexpression of the body's normal inflammatory response involving various effector cells, cytokines, and inflammatory mediators, which regulate the body's immune response through different signalling pathways. Forkhead box transcription factors are evolutionarily conserved transcription factors that play a crucial role in various cellular processes, such as cell cycle progression, proliferation, differentiation, migration, metabolism, and DNA damage response. Transcription factors control protein synthesis by regulating gene transcription levels, resulting in diverse biological outcomes. The Fox family plays a role in activating or inhibiting the expression of various molecules related to ALI/ARDS through phosphorylation, acetylation/deacetylation, and control of multiple signalling pathways. An in-depth analysis of the integrated Fox family's role in ALI/ARDS can aid in the development of potential diagnostic and therapeutic targets for the condition.

Enhanced efficacy of BCG vaccine formulated in adjuvant is dependent on IL-17A expression

A new, more effective vaccine against tuberculosis (TB) is urgently needed to curtail the current TB problem. The only licensed vaccine, BCG, has been shown to have highly variable protective efficacy in several clinical trials ranging from zero to 80 % against TB disease. We have previously reported that BCG formulated in dimethyl dioctadecyl-ammonium bromide (DDA) with D-(+)-Trehalose 6,6'-Dibehenate (TDB) adjuvant (BCG + Adj) is significantly more protective than BCG alone following murine aerosol Mycobacterium tuberculosis infection. Here we investigate the immunological basis for this improved efficacy by examining expression of different immune markers and cytokines in the lungs of vaccinated mice after M. tuberculosis aerosol challenge. We found significantly greater numbers of pulmonary IL-17A-expressing CD4+ T cells in mice immunized with BCG+Adj as compared to nonvaccinated and BCG-immunized mice at one-month post-challenge and that the enhanced protection was abrogated in IL-17A-deficient mice. Furthermore, we found significantly higher levels of IL-17A, IL-12p40 and IL-33 expression in the lungs of BCG + Adj immunized animals relative to nonvaccinated mice after M. tuberculosis challenge. These results demonstrate that the DDA/TDB adjuvant increases expression of IL-17A in response to the BCG vaccine and that these augmented IL-17A levels enhance control of M. tuberculosis infection.

Gut-derived immune cells and the gut-lung axis in ARDS

The gut serves as a vital immunological organ orchestrating immune responses and influencing distant mucosal sites, notably the respiratory mucosa. It is increasingly recognized as a central driver of critical illnesses, with intestinal hyperpermeability facilitating bacterial translocation, systemic inflammation, and organ damage. The "gut-lung" axis emerges as a pivotal pathway, where gut-derived injurious factors trigger acute lung injury (ALI) through the systemic circulation. Direct and indirect effects of gut microbiota significantly impact immune responses. Dysbiosis, particularly intestinal dysbiosis, termed as an imbalance of microbial species and a reduction in microbial diversity within certain bodily microbiomes, influences adaptive immune responses, including differentiating T regulatory cells (Tregs) and T helper 17 (Th17) cells, which are critical in various lung inflammatory conditions. Additionally, gut and bone marrow immune cells impact pulmonary immune activity, underscoring the complex gut-lung interplay. Moreover, lung microbiota alterations are implicated in diverse gut pathologies, affecting local and systemic immune landscapes. Notably, lung dysbiosis can reciprocally influence gut microbiota composition, indicating bidirectional gut-lung communication. In this review, we investigate the pathophysiology of ALI/acute respiratory distress syndrome (ARDS), elucidating the role of immune cells in the gut-lung axis based on recent experimental and clinical research. This exploration aims to enhance understanding of ALI/ARDS pathogenesis and to underscore the significance of gut-lung interactions in respiratory diseases.

Bifidobacterium mitigates autoimmune hepatitis by regulating IL-33-induced Treg/Th17 imbalance via the TLR2/4 signaling pathway

The present work aims to evaluate the efficacy of Live Combined Bifidobacterium, Lactobacillus and Enterococcus Capsules (LCBLECs), a probiotic drug containing Bifidobacterium, in the treatment of autoimmune hepatitis (AIH). In this study, a mouse model of experimental autoimmune hepatitis (EAH) was established to investigate the effects of LCBLECs on AIH. The results showed that LCBLECs improved dysbiosis of gut microbiota, reduced liver injury, restored liver function, and maintained Treg/Th17 balance in EAH mice. In addition, LCBLECs restored Treg/Th17 balance in EAH mice by downregulating IL-33 production. Besides, LCBLECs also suppress IL-33 upregulation in EAH mice by inhibiting the TLR2/4 signaling pathway. Furthermore, LCBLECs also mitigated dysbiosis of gut microbiota and enhanced the efficacy of conventional treatment for AIH patients. To sum up, our findings revealed that LCBLECs exerted therapeutic effects on EAH mice by improving Treg/Th17 imbalance in an IL-33-dependent manner via the TLR2/4 signaling pathway and relieved the clinical symptoms of AIH patients, indicating Bifidobacterium supplementation with LCBLECs might be a potential adjuvant therapy for AIH treatment.

Elk1 enhances inflammatory cell infiltration and exacerbates acute lung injury/acute respiratory distress syndrome by suppressing Fcgr2b transcription

OBJECTIVE

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are associated with significant mortality rates. The role of Fcgr2b in the pathogenesis of ALI/ARDS is not fully elucidated. This study aimed to investigate the functions of Fcgr2b in ALI/ARDS and explore its underlying mechanisms.

METHODS

Methods: In this study, rat models of ARDS and pulmonary microvascular endothelial cell (PMVEC) injury models were established through the administration of lipopolysaccharide (LPS). The expression levels of Fcgr2b and Elk1 were quantified in both LPS-induced ARDS rats and PMVECs. Subsequent gain- and loss-of-function experiments were conducted, followed by comprehensive assessments of lung tissue for pathomorphological changes, edema, glycogen storage, fibrosis, and infiltration of inflammatory cells. Additionally, bronchoalveolar lavage fluid was analyzed for T-helper 17 (Th17) cell infiltration, inflammatory response, and microvascular permeability to evaluate lung injury severity in ARDS models. Furthermore, the activity, cytotoxicity, apoptosis, and angiogenic potential of PMVECs were assessed to gauge cell injury. The interaction between Elk1 and Fcgr2b was also examined to confirm their regulatory relationship.

RESULTS

In the context of LPS-induced ARDS and PMVEC injury, Fcgr2b expression was markedly reduced, whereas Elk1 expression was elevated. Overexpression of Fcgr2b led to a decrease in Th17 cell infiltration and mitigated lung tissue damage in ARDS models, in addition to reducing LPS-induced injury in PMVECs. Elk1 was found to suppress Fcgr2b transcription through the recruitment of histone 3 lysine 9 trimethylation (H3K9me3). Knockdown of Elk1 diminished Th17 cell infiltration and lung tissue damage in ARDS models, and alleviated LPS-induced injury in PMVECs, effects that were reversed upon Fcgr2b upregulation.

CONCLUSION

Elk1 negatively regulates Fcgr2b transcription, thereby augmenting the inflammatory response and exacerbating lung injury in LPS-induced ALI/ARDS.

Th17/Treg balance: the bloom and wane in the pathophysiology of sepsis

Sepsis is a multi-organ dysfunction characterized by an unregulated host response to infection. It is associated with high morbidity, rapid disease progression, and high mortality. Current therapies mainly focus on symptomatic treatment, such as blood volume supplementation and antibiotic use, but their effectiveness is limited. Th17/Treg balance, based on its inflammatory property, plays a crucial role in determining the direction of the inflammatory response and the regression of organ damage in sepsis patients. This review provides a summary of the changes in T-helper (Th) 17 cell and regulatory T (Treg) cell differentiation and function during sepsis, the heterogeneity of Th17/Treg balance in the inflammatory response, and the relationship between Th17/Treg balance and organ damage. Th17/Treg balance exerts significant control over the bloom and wanes in host inflammatory response throughout sepsis.

The Correlation of Serum Calpain 1 Activity and Concentrations of Interleukin 33 in COVID-19 Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is one of the most severe complications of the COVID-19 disease. The role of IL-33 and calpain 1 was previously described in lung infections and lung tissue damage. Our study examined the association between serum calpain 1 activity and IL-33 concentration in patients with COVID-19 ARDS. In the research, we included 80 subjects who had COVID-19 pneumonia and divided them into 2 groups: 40 subjects with ARDS and 40 subjects without ARDS. The basis of the research was the collection of subjects' data and the sampling of peripheral venous blood. The concentration of IL-33 was determined by the ELISA method and the activity of calpain 1 by the fluorometry method. Our research showed elevated calpain 1 activity and IL-33 concentration in the serum of COVID-19 patients who developed ARDS compared to those who did not develop ARDS and a positive correlation between them was established. Further, a positive correlation was established between the examined parameters and the severity of the disease, proinflammatory markers, and the use of mechanical ventilation. These results indicate a possible association and role of calpain 1 and IL-33 with the development of ARDS in COVID-19 patients.

Th17/Treg Imbalance: Implications in Lung Inflammatory Diseases

Regulatory T cells (Tregs) and T helper 17 cells (Th17) are two CD4⁺ T cell subsets with antagonist effects. Th17 cells promote inflammation, whereas Tregs are crucial in maintaining immune homeostasis. Recent studies suggest that Th17 cells and Treg cells are the foremost players in several inflammatory diseases. In this review, we explore the present knowledge on the role of Th17 cells and Treg cells, focusing on lung inflammatory diseases, such as chronic obstructive pulmonary disease (COPD), acute respiratory distress syndrome (ARDS), sarcoidosis, asthma, and pulmonary infectious diseases.