Serum IL-36 cytokines levels in idiopathic pulmonary fibrosis and connective tissue disease-associated interstitial lung diseases

Cardiovascular disease in connective tissue disease-associated interstitial lung disease: A systematic review and meta-analysis of observational studies

OBJECTIVES

We performed a systematic review and meta-analysis to assess whether patients with connective tissue disease (CTD)-associated interstitial lung diseases (ILD) have an increased prevalence of cardiovascular (CV) disease and to validate associated risk factors.

METHODS

The PRISMA guidelines and PICO model were followed. We searched PubMed, Embase, Cochrane Library databases, Scopus, and Directory of Open Access Journals from inception to April 2024.

RESULTS

Thirteen studies comprising of 12,520 patients were included. Patients with CTD-ILD had a significantly increased risk of CV disease than patients with CTD (relative risk [RR] = 1.65, 95 % confidence interval [CI]: 1.41, 1.93), which are related to the proportion of men (P = 0.001) and the proportion of smokers (P = 0.045). Subgroup analysis found that patients with CTD-ILD had a higher risk of heart failure (RR = 2.84, 95 % CI: 1.50, 5.39), arrhythmia (RR = 1.55, 95 % CI: 1.22, 1.97) than patients with CTD. Another subgroup analysis showed that RA-ILD and SSc-ILD were associated with an increased risk of CV disease, but not IIM-ILD and MCTD-ILD (RA-ILD: RR = 2.19, 95 % CI: 1.27, 3.80; SSc-ILD: RR = 1.53, 95 % CI: 1.29, 1.82). Besides, patients with CTD-ILD had a higher prevalence of pulmonary arterial hypertension (RR = 2.48, 95 % CI: 1.69, 3.63) than patients with CTD.

CONCLUSIONS

Patients with CTD-ILD had a 1.65 times increased risk of CV than patients with CTD-non-ILD, with increased prevalence of heart failure and arrhythmia. The risk of CV disease in SSc-ILD and RA-ILD is increased and we should pay more attention to male smokers. In addition, compared with CTD patients, CTD-ILD patients had a higher risk of pulmonary arterial hypertension.

The role of interleukin-36 in health and disease states

The interleukin (IL)-1 superfamily upregulates immune responses and maintains homeostasis between the innate and adaptive immune systems. Within the IL-1 superfamily, IL-36 plays a pivotal role in both innate and adaptive immune responses. Of the four IL-36 isoforms, three have agonist activity (IL-36α, IL-36β, IL-36γ) and the fourth has antagonist activity (IL-36 receptor antagonist [IL-36Ra]). All IL-36 isoforms bind to the IL-36 receptor (IL-36R). Binding of IL-36α/β/γ to the IL-36R recruits the IL-1 receptor accessory protein (IL-1RAcP) and activates downstream signalling pathways mediated by nuclear transcription factor kappa B and mitogen-activated protein kinase signalling pathways. Antagonist binding of IL-36Ra to IL-36R inhibits recruitment of IL-1RAcP, blocking downstream signalling pathways. Changes in the balance within the IL-36 cytokine family can lead to uncontrolled inflammatory responses throughout the body. As such, IL-36 has been implicated in numerous inflammatory diseases, notably a type of pustular psoriasis called generalized pustular psoriasis (GPP), a chronic, rare, potentially life-threatening, multisystemic skin disease characterised by recurrent fever and extensive sterile pustules. In GPP, IL-36 is central to disease pathogenesis, and the prevention of IL-36-mediated signalling can improve clinical outcomes. In this review, we summarize the literature describing the biological functions of the IL-36 pathway. We also consider the evidence for uncontrolled activation of the IL-36 pathway in a wide range of skin (e.g., plaque psoriasis, pustular psoriasis, hidradenitis suppurativa, acne, Netherton syndrome, atopic dermatitis and pyoderma gangrenosum), lung (e.g., idiopathic pulmonary fibrosis), gut (e.g., intestinal fibrosis, inflammatory bowel disease and Hirschsprung's disease), kidney (e.g., renal tubulointerstitial lesions) and infectious diseases caused by a variety of pathogens (e.g., COVID-19; Mycobacterium tuberculosis, Pseudomonas aeruginosa, Streptococcus pneumoniae infections), as well as in cancer. We also consider how targeting the IL-36 signalling pathway could be used in treating inflammatory disease states.

Interleukin-36 receptor antagonist stimulation in vitro inhibits peripheral and lung-resident T cell response isolated from patients with ventilator-associated pneumonia

Interleukin-36 (IL-36) cytokine family members play an immunomodulatory function to immune cells through IL-36 receptor signaling pathway. However, the regulatory role of IL-36 exerted on T cells is not completely elucidated in patients with ventilator-associated pneumonia (VAP). For this purpose, this study enrolled 51 VAP patients and 27 controls. IL-36 levels were measured by ELISA. The mRNA levels of IL-36 receptor subunits were determined by real-time PCR. CD4+ and CD8+ T cells were enriched, and stimulated with recombinant IL-36 receptor antagonist (IL-36RA). The influence of IL-36RA on transcription factors and cytokine secretions by CD4+ T cells was investigated. The modulatory function of IL-36RA on CD8+ T cells was assessed by measuring target cell death and cytokine secretions. There were no significant differences in serum IL-36 levels between VAP patients and controls. Only IL-36RA, but not IL-36α, IL-36β, or IL-36γ, in bronchoalveolar lavage fluid was elevated in infection site of VAP patients. IL-36 receptor subunits in CD4+ and CD8+ T cells were comparable between VAP patients and controls. 10 ng/mL of IL-36RA stimulation dampened peripheral effector CD4+ T cell response isolated from both VAP patients and controls. Target cell death mediated by CD8+ T cells isolated from BAFL of VAP patients was suppressed by 100 ng/mL of IL-36RA stimulation in vitro. The down-regulations of perforin, granzyme B, interferon-γ, tumor necrosis factor-α, and Fas ligand following IL-36RA stimulation in vitro were responsible for reduced CD8+ T cell-mediated cytotoxicity. IL-36RA revealed an immunosuppressive property for T cell response in vitro, and may be involved in the protective mechanism in VAP patients.

IL-38 alleviates airway remodeling in chronic asthma via blocking the profibrotic effect of IL-36γ

Airway remodeling is a major feature of asthma. Interleukin (IL)-36γ is significantly upregulated and promotes airway hyper-responsiveness (AHR) in asthma, but its role in airway remodeling is unknown. Here, we aimed to investigate the role of IL-36γ in airway remodeling, and whether IL-38 can alleviate airway remodeling in chronic asthma by blocking the effects of IL-36γ. IL-36γ was quantified in mice inhaled with house dust mite (HDM). Extracellular matrix (ECM) deposition in lung tissues and AHR were assessed following IL-36γ administration to mice. Airway inflammation, AHR, and remodeling were evaluated after IL-38 or blocking IL-36 receptor (IL-36R) treatment in asthmatic mice. The effects of lung fibroblasts stimulated with IL-36γ and IL-38 were quantified in vitro. Increased expression of IL-36γ was detected in lung tissues of HDM-induced asthmatic mice. The intratracheal instillation of IL-36γ to mice significantly enhanced the ECM deposition, AHR, and the number of activated lung fibroblasts around the airways. IL-38 or blocking IL-36R treated asthmatic mice showed a significant alleviation in the airway inflammation, AHR, airway remodeling, and number of activated fibroblasts around airways as compared with the HDM group. In vitro, IL-36γ promoted the activation and migration of human lung fibroblasts (HFL-1). The administration of IL-38 can counteract these biological processes induced by IL-36γ in HFL-1cells. The results indicated that IL-38 can mitigate airway remodeling by blocking the profibrotic effects of IL-36γ in chronic asthma. IL-36γ may be a new therapeutic target, and IL-38 is a potential candidate agent for inhibiting airway remodeling in asthma.

Theroleofinterleukin-1familyinfibroticdiseases

Fibrosis refers to the phenomenon that fibrous connective tissues are increased and parenchymal cells are decreased in organs or tissues such as lung, heart, liver, kidney, skin and so on. It usually occurs at the late stage of repair of chronic or recurrent tissue damage. Fibrotic disease is the main factor for the morbidity and mortality of all tissues and organ systems. Long-term fibrosis can lead to organ and tissue dysfunction and even failure. Interleukin -1 family cytokines are a series of classical inflammatory factors and involved in the occurrence and development process of multiple fibrotic diseases, its biological function, relationship with diseases and application are more and more favored by scientists from various countries. So far, 11 cytokines and 10 receptors of IL-1 family have been identified. In this paper, the cytokines, receptors, signaling pathways and biological functions of IL-1 family are summarized, and the correlation with fibrosis diseases is analyzed.

Clinical significance of elevated serum IL-36γ levels in patients with early-stage Hashimoto's thyroiditis

OBJECTIVES

Hashimoto's thyroiditis (HT) is the predominant cause of primary hypothyroidism. Interleukin (IL)-36γ is a member of the IL-36 family. Recently, IL-36γ was shown to possess proinflammatory properties in autoimmune diseases. However, the role of IL-36γ in HT is insufficiently understood. The purpose of the present study was to investigate the potential relationship between IL-36γ and HT.

DESIGN & METHODS

We included 100 subjects, among whom, 52 had early-stage HT and 48 were healthy controls (HC). The subjects' basic clinical information was obtained through physical examination and clinical histories of signs and symptoms. Thyroid function and measurements of thyroid-stimulating hormone (TSH), free triiodothyronine 3, free triiodothyronine 4 (FT4), thyroid peroxidase antibody (TPO-Ab), and thyroid globulin antibody were measured using a fully automated chemiluminescent immunoassay analyzer. The expression levels of serum IL-36γ were determined using an enzyme-linked immunosorbent assay.

RESULTS

The serum IL-36γ level in the HT group was significantly higher compared with that of the HC group [91.91 (67.52, 130.90) pg/mL vs 62.50 (44.61, 91.53) pg/mL, P < 0.0001]. Correlation analysis showed a negative correlation between serum IL-36γ and TPO-Ab titers in the HT group (r = -0.3507, P = 0.0054). According to receiver operating characteristic curve analysis, the area under the curve (AUC) for IL-36γ was 0.7278 (P < 0.0001), and the AUC for IL-36γ combined with TSH and FT4 was 0.8109 (P < 0.0001).

CONCLUSIONS

The present study indicates that serum IL-36γ expression is increased in patients with HT and negatively correlates with TPO-Ab. Our findings suggest that IL-36γ may be involved in the development of HT and may therefore serve as a potential new diagnostic biomarker for HT.

Plasma IL-36α and IL-36γ as Potential Biomarkers in Interstitial Lung Disease Associated with Rheumatoid Arthritis: a Pilot Study in the Chinese Population

Interstitial lung disease (ILD) is a frequent extra-articular manifestation of rheumatoid arthritis (RA) and increases mortality in patients with RA. Early identification of ILD, especially the usual interstitial pneumonia (UIP) pattern with a poor prognosis, is important for guiding treatment of RA-ILD and preventing damage resulting from a delay in diagnosis. Interleukin-36 (IL-36) cytokines are involved in connective tissue diseases. However, IL-36 expression in RA-ILD is unknown. In this study, the clinical relevance of plasma IL-36 cytokines was evaluated in 39 patients with RA-ILD and three other groups (30 healthy controls [HCs], 35 RA patients without ILD, and 27 patients with idiopathic pulmonary fibrosis [IPF]) in the Chinese population. Plasma IL-36α and IL-36γ concentrations were elevated in patients with RA-ILD compared with those in HCs and patients with RA. RA-ILD patients with UIP pattern had higher plasma IL-36γ concentrations than those with RA-ILD without UIP, but these were lower than those in patients with IPF. Receiver operating curve analysis suggested that IL-36α and IL-36γ were potential biomarkers for identifying ILD in patients with RA. Additionally, the optimal cutoff value of IL-36γ for distinguishing RA-ILD with the UIP pattern from RA-ILD without UIP was 555.40 pg/mL and that for distinguishing RA-ILD from IPF was 655.10 pg/mL. No significant difference in plasma IL-36β or IL-36Ra concentrations was found between patients with RA-ILD and the three other groups. We also found that the lungs originating from different types of patients with PF, including RA-ILD and IPF, and those from mice following bleomycin-induced PF were characterized by increased IL-36γ expression. Our findings suggest that using IL-36 cytokines to identify patients with RA for further ILD workups may provide additional diagnostic value to the current clinically available assays. Moreover, IL-36γ may help to identify the presence of the UIP pattern in patients with RA-ILD and to discriminate RA-ILD from IPF.

IL-38 in modulating hyperlipidemia and its related cardiovascular diseases

Hyperlipidemia is confirmed to be associated with several health problems that include the combination of diabetes mellitus, obesity, and hypertension, ie, metabolic syndrome. Although the lipid-lowering therapy is an effective treatment in hyperlipidemia and its related cardiovascular diseases (CVDs), the persistence of high atherosclerotic risk is notable which could not be simply explained as a phenomenon of hyperlipidemia. Concerning on this notion, it is imperative to identify novel biomarkers which could monitor treatment and predict adverse cardiovascular events. It is demonstrated that the chronic inflammatory response caused by immune cells is a characteristic of hyperlipidemia and atherosclerosis. Notably, among several inflammatory related cytokines, interleukin 38 (IL-38), as a member of the IL-1 family, plays an important role in anti-inflammatory response by binding with its receptor which inhibits the downstream signaling pathways. In addition, IL-38 suppresses the expression of inflammatory factors mainly through the mitogen-activated protein kinase (MAPK). At the cellular level, IL-38 could inhibit the CD4 positive T lymphocyte into T-helper 17 (Th-17) lymphocyte which further enhances the immunosuppressive activity of the T-regulatory lymphocyte (T-reg) to inhibit the inflammatory response. Consistently, IL-38 is shown to be strongly correlated to development of hyperlipidemic related CVDs. In this review, the roles of IL-38 in the development of hyperlipidemia are fully summarized. Furthermore, a theoretical basis for further in-depth research of IL-38 for treatment of hyperlipidemia is also provided.