Leptin Promoted IL-17 Production from ILC2s in Allergic Rhinitis

The role of hormones in ILC2-driven allergic airway inflammation

Group 2 innate lymphoid cells (ILC2s) are a type of innate immune cells that produce a large amount of IL-5 and IL-13 and two cytokines that are crucial for various processes such as allergic airway inflammation, tissue repair and tissue homeostasis. It is known that damaged epithelial-derived alarmins, such as IL-33, IL-25 and thymic stromal lymphopoietin (TSLP), are the predominant ILC2 activators that mediate the production of type 2 cytokines. In recent years, abundant studies have found that many factors can regulate ILC2 development and function. Hormones synthesized by the body's endocrine glands or cells play an important role in immune response. Notably, ILC2s express hormone receptors and their proliferation and function can be modulated by multiple hormones during allergic airway inflammation. Here, we summarize the effects of multiple hormones on ILC2-driven allergic airway inflammation and discuss the underlying mechanisms and potential therapeutic significance.

Regulatory ILC2-Role of IL-10 Producing ILC2 in Asthma

Over the past two decades, a growing body of evidence observations have shown group two innate lymphoid cells (ILC2) to be critical drivers of Type 2 (T2) inflammatory responses associated with allergic inflammatory conditions such as asthma. ILC2 releases copious amounts of pro-inflammatory T2 cytokines-interleukin (IL)-4, IL-5, IL-9, and IL-13. This review provides a comprehensive overview of the newly discovered regulatory subtype of ILC2 described in murine and human mucosal tissue and blood. These KLRG1+ILC2 have the capacity to produce the anti-inflammatory cytokine IL-10. Papers compiled in this review were based on queries of PubMed and Google Scholar for articles published from 2000 to 2023 using keywords "IL-10" and "ILC2". Studies with topical relevance to IL-10 production by ILC2 were included. ILC2 responds to microenvironmental cues, including retinoic acid (RA), IL-2, IL-4, IL-10, and IL-33, as well as neuropeptide mediators such as neuromedin-U (NMU), prompting a shift towards IL-10 and away from T2 cytokine production. In contrast, TGF-β attenuates IL-10 production by ILC2. Immune regulation provided by IL-10+ILC2s holds potential significance for the management of T2 inflammatory conditions. The observation of context-specific cues that alter the phenotype of ILC warrants examining characteristics of ILC subsets to determine the extent of plasticity or whether the current classification of ILCs requires refinement.

Allergic Diseases and Childhood Obesity: A Detrimental Link?

Several epidemiological studies have described childhood obesity as a risk factor for atopic disease, particularly asthma. At the same time, this association seems to be more conflicting for allergic rhinitis, atopic dermatitis, and chronic urticaria. This article aims to deepen the possibility of a relationship between childhood obesity and allergic diseases. As regards asthma, the mechanical and inflammatory effects of obesity can lead to its development. In addition, excess adiposity is associated with increased production of inflammatory cytokines and adipokines, leading to low-grade systemic inflammation and an increased risk of asthma exacerbations. Allergic rhinitis, atopic dermatitis, food allergies, and chronic urticaria also seem to be related to this state of chronic low-grade systemic inflammation typical of obese children. Vitamin D deficiency appears to play a role in allergic rhinitis, while dyslipidemia and skin barrier defects could explain the link between obesity and atopic dermatitis. Starting from this evidence, it becomes of fundamental importance to act on body weight control to achieve general and allergic health, disentangling the detrimental link between obesity allergic diseases and childhood obesity. Further studies on the association between adiposity and atopy are needed, confirming the biologically active role of fat tissue in the development of allergic diseases and exploring the possibility of new therapeutic strategies.

Transcriptional regulation of innate lymphoid cells and T cells by aryl hydrocarbon receptor

The aryl hydrocarbon receptor (Ahr) is a ligand-dependent transcription factor and facilitates immune cell environmental sensing through its activation by cellular, dietary, and microbial metabolites, as well as environmental toxins. Although expressed in various cell types, Ahr in innate lymphoid cells (ILCs) and their adaptive T cell counterparts regulates essential aspects of their development and function. As opposed to T cells, ILCs exclusively rely on germ-line encoded receptors for activation, but often share expression of core transcription factors and produce shared effector molecules with their T cell counterparts. As such, core modules of transcriptional regulation are both shared and diverge between ILCs and T cells. In this review, we highlight the most recent findings regarding Ahr’s transcriptional regulation of both ILCs and T cells. Furthermore, we focus on insights elucidating the shared and distinct mechanisms by which Ahr regulates both innate and adaptive lymphocytes.

The role of Th17 cells in endocrine organs: Involvement of the gut, adipose tissue, liver and bone

T Helper 17 (Th17) cells are adaptive immune cells that play myriad roles in the body. Immune-endocrine interactions are vital in endocrine organs during pathological states. Th17 cells are known to take part in multiple autoimmune diseases over the years. Current evidence has moved from minimal to substantial that Th17 cells are closely related to endocrine organs. Diverse tissue Th17 cells have been discovered within endocrine organs, including gut, adipose tissue, liver and bone, and these cells are modulated by various secretions from endocrine organs. Th17 cells in these endocrine organs are key players in the process of an array of metabolic disorders and inflammatory conditions, including obesity, insulin resistance, nonalcoholic fatty liver disease (NAFLD), primary sclerosing cholangitis (PSC), osteoporosis and inflammatory bowel disease (IBD). We reviewed the pathogenetic or protective functions played by Th17 cells in various endocrine tissues and identified potential regulators for plasticity of it. Furthermore, we discussed the roles of Th17 cells in crosstalk of gut-organs axis.

Use of the systemic inflammation response index (SIRI) as a novel prognostic marker for patients on peritoneal dialysis

Background

The systemic inflammatory response index (SIRI), a novel inflammation maker, has proven to be associated with prognostic outcomes in various diseases. However, few studies have been conducted assessing how SIRI may influence outcomes of patients on peritoneal dialysis (PD). Herein, we assessed the predictive value of SIRI on mortality all-cause mortality, including cardiovascular disease (CVD) in PD patients.

Methods

A total of 646 PD patients were enrolled in this study. PD patients received regular PD treatments at the Zhujiang Hospital from 1 January 2011 to 31 December 2018. SIRI values could be computed as follows: neutrophil count × monocyte count/lymphocyte count. Patients were divided into two groups according to the median level of SIRI. Cox regression analysis and Kaplan–Meier methods were applied to analyze the relationship between SIRI and mortality outcomes in PD patients.

Results

During the median 31-month follow-up period, 97 (15.0%) PD patients died from all-causes, and 47 (49.0%) died of CVD. Kaplan–Meier analyses revealed that a high SIRI corresponded to the high mortality of all-cause deaths, including CVD (both p < 0.001) in patients on PD. After adjusting for potential confounders, the higher SIRI level was significantly associated with an increased all-cause mortality (HR: 2.007, 95% CI: 1.304–3.088, p = 0.002) and cardiovascular mortality (HR: 2.847, 95% CI: 1.445–5.608, p = 0.002).

Conclusions

SIRI was a promising predictor of mortality in PD patients, with a higher SIRI corresponding to increased risk of mortality.

Role of leptin/ILC2 axis in allergic rhinitis in obese children

OBJECTIVES

Since the leptin participates in the upregulation of type 2 innate lymphoid cells (ILC2s). We investigated the role of the leptin/ILC2 axis in AR pathogenesis in Chinese paediatric patients with obesity.

METHODS

Seventy AR paediatric patients with or without obesity and 30 healthy obese subjects were enrolled. The levels of leptin, its receptor and ILC2 milieu were measured, and correlations between them and clinical symptom severity and between ILC2 milieu and leptin levels were assessed. Changes of ILC2 milieu in AR patients after leptin stimulation were also detected.

RESULTS

Levels of leptin, its receptor and ILC2 milieu levels were significantly higher in the disease than in the controls, and highest in the obese-AR group. The leptin/ILC2 axis and severity of clinical symptoms in obese patients with AR were significantly correlated, similarly to what was observed between leptin/leptin receptors and ILC2 milieu. Recombinant leptin could significantly increased the levels of ILC2 milieu in the obese-AR group.

CONCLUSIONS

These findings suggest the unique function ofthe leptin/ILC2 axis in obese paediatric AR patients. The mechanism by which obesity promotes AR in paediatric patients may be related to the leptin/ILC2 axis.

The Role of Airway Epithelial Cell Alarmins in Asthma

The airway epithelium is the first line of defense for the lungs, detecting inhaled environmental threats through pattern recognition receptors expressed transmembrane or intracellularly. Activation of pattern recognition receptors triggers the release of alarmin cytokines IL-25, IL-33, and TSLP. These alarmins are important mediators of inflammation, with receptors widely expressed in structural cells as well as innate and adaptive immune cells. Many of the key effector cells in the allergic cascade also produce alarmins, thereby contributing to the airways disease by driving downstream type 2 inflammatory processes. Randomized controlled clinical trials have demonstrated benefit when blockade of TSLP and IL-33 were added to standard of care medications, suggesting these are important new targets for treatment of asthma. With genome-wide association studies demonstrating associations between single-nucleotide polymorphisms of the TSLP and IL-33 gene and risk of asthma, it will be important to understand which subsets of asthma patients will benefit most from anti-alarmin therapy.

Possible Role of Leptin in Atopic Dermatitis: A Literature Review

Atopic dermatitis (AD) is the most frequent chronic inflammatory skin disease, and its incidence has been rapidly increasing in developed countries in the last years. AD presents a high degree of heterogeneity due to biases and confounding factors such as age range, sex, or ethnicity. For those reasons, the search for new biomarkers is crucial. At the same time, obesity, which is a global health problem, has also increased over the years. It has been associated with many pathophysiological states, including skin diseases such as AD, mostly in childhood. Obesity promotes a low grade inflammation driven by many different cytokines and adipokines, including leptin, which has a key role in many other diseases due to its pleiotropic effects. Leptin also has a role in both skin and allergic diseases very related to AD. Thus, this adipokine could have an important role in the pathogenesis of AD, especially in its chronicity. Despite the limited literature available, there is some evidence that leads us to consider leptin as an important adipokine in this skin disease. For this reason, here we have reviewed the role of leptin in the pathophysiology of AD.

Neuroimmune Interactions and Rhythmic Regulation of Innate Lymphoid Cells

The Earth’s rotation around its axis, is one of the parameters that never changed since life emerged. Therefore, most of the organisms from the cyanobacteria to humans have conserved natural oscillations to regulate their physiology. These daily oscillations define the circadian rhythms that set the biological clock for almost all physiological processes of an organism. They allow the organisms to anticipate and respond behaviorally and physiologically to changes imposed by the day/night cycle. As other physiological systems, the immune system is also regulated by circadian rhythms and while diurnal variation in host immune responses to lethal infection have been observed for many decades, the underlying mechanisms that affect immune function and health have only just started to emerge. These oscillations are generated by the central clock in our brain, but neuroendocrine signals allow the synchronization of the clocks in peripheral tissues. In this review, we discuss how the neuroimmune interactions create a rhythmic activity of the innate lymphoid cells. We highlight how the disruption of these rhythmic regulations of immune cells can disturb homeostasis and lead to the development of chronic inflammation in murine models.