Interleukin-17A: Potential mediator and therapeutic target in hypertension

TH17/Treg lymphocyte balance is regulated by beta adrenergic and cAMP signaling

BACKGROUND

Post-traumatic stress disorder (PTSD) is a debilitating psychological disorder that also presents with neuroimmune irregularities. Patients display elevated sympathetic tone and are at an increased risk of developing secondary autoimmune diseases. Previously, using a mouse model of repeated social defeat stress (RSDS) that recapitulates certain features of PTSD, we demonstrated that elimination of sympathetic signaling to T-lymphocytes specifically limited their ability to produce pro-inflammatory interleukin 17A (IL-17A); a cytokine implicated in the development of many autoimmune disorders. However, the mechanism linking sympathetic signaling to T-lymphocyte IL-17A production remained unclear.

METHODS

Using a modified version of RSDS that allows for both males and females, as well as ex vivo models of T-lymphocyte polarization, we assessed the impact and mechanism of adrenergic receptor blockade (genetically and pharmacologically) and catecholamine depletion on T-lymphocyte differentiation to IL-17A-producing subtypes (i.e., TH17).

RESULTS

Only pharmacological inhibition of the beta 1 and 2 adrenergic receptors (β1/2) significantly decreased circulating IL-17A levels after RSDS, but did not impact other pro-inflammatory cytokines (e.g.,IL-6, TNF-α, and IL-10). This finding was confirmed using RSDS with both global β1/2 receptor knock-out mice, as well as by adoptively transferring β1/2 knock-out T-lymphocytes into immunodeficient hosts. Ex vivo polarized T-lymphocytes produced significantly less IL-17A with the blockade of β1/2 signaling, even in the absence of exogenous sympathetic neurotransmitter supplementation, which suggested T-lymphocyte-produced catecholamines may be involved in IL-17A production. Furthermore, cyclic AMP (cAMP) was demonstrated to be mechanistically involved in driving IL-17A production in T-lymphocytes, and amplifying cAMP signaling could restore IL-17A deficits caused by the absence of β1/2 signaling. Last, removal of β1/2 and cAMP signaling, even in IL-17A polarizing conditions, promoted regulatory T-lymphocyte (Treg) polarization, suggesting adrenergic signaling plays a role in the switching between pro- and anti-inflammatory T-lymphocyte subtypes.

CONCLUSIONS

Our data depict a novel role for β1/2 adrenergic and cAMP signaling in the balance of TH17/Treg lymphocytes. These findings provide a new target for pharmacological therapy in both psychiatric and autoimmune diseases associated with IL-17A-related pathology.

Ankylosing spondylitis and cardiovascular disease: A two-sample Mendelian randomization analysis

Epidemiological research has demonstrated that people suffering from ankylosing spondylitis (AS) have a greater chance of developing cardiovascular disease (CVD), though the potential link between AS genetics and CVD risk is uncertain. This research examined the potential link between CVD outcomes and AS which is genetically determined. A two-sample Mendelian randomization analysis was conducted using data from European population genome-wide association study of AS and CVD. We selected single nucleotide polymorphisms closely associated with AS genetic susceptibility as instrumental variables, and used inverse variance weighted as the main method to analyze the causal effects of AS on 7 CVDs (heart failure, atrial fibrillation, hypertension, ischemic stroke, etc). To further reinforce our results, we conducted replication analyses, sensitivity analyses, and instrumental variable strength assessments. In the European population, it was observed that AS genetic susceptibility was correlated with a higher risk of heart failure (odds ratios [OR] = 1.0128, 95% confidence intervals [CI]: 1.0037-1.0219, P = .0058), hypertension (OR = 1.0143, 95% CI: 1.0038-1.0248, P = .0073), and ischemic stroke (OR = 1.0151, 95% CI: 1.0049-1.0255, P = .0036). However, it was not associated with coronary heart disease, cardiomyopathy, valvular heart disease, or atrial fibrillation (all P > .05). A sensitivity analysis was conducted to validate the reliability of the results. Evidence from the European population has indicated a correlation between AS and heart failure, hypertension, and ischemic stroke. Further investigations should be conducted to explore the underlying mechanisms of action.

Advances in Understanding of the Role of Immune Cell Phenotypes in Hypertension and Associated Vascular Disease

Many studies in the past 20 years have identified a contribution of inflammation and immune mechanisms to the pathophysiology of hypertension. Innate and adaptive immunity participate in this process. Among innate immune cells, macrophages and monocytes as well as dendritic cells, myeloid-derived suppressor cells, and neutrophils directly or via formation of neutrophil extracellular traps, play roles in the modulation of the inflammatory response in hypertension. Among adaptive immune cells, T and B cells have been implicated to varying degrees, particularly interleukin (IL)-17- and interferon γ-producing T lymphocytes, antagonized by T regulatory lymphocytes that are anti-inflammatory via production of IL-10. Among T cells that produce abundant IL-17, γδ T cells are unconventional T lymphocytes that are infrequent in the circulation in contrast to the much more abundant circulating αβ T lymphocytes, but are found mostly in tissues, and appear to play a role in triggering and sustaining inflammation in hypertension leading to vascular and renal injury. This review will provide an overview of these different immune cell phenotypes involved in the immune pathophysiology of hypertension and associated vascular disease.

A new era in the treatment of kidney diseases: NLRP3 inflammasome and cytokine-targeted therapies

The kidneys are crucial for filtering blood, managing overall body water, electrolyte, and acid-base balance, and regulating blood pressure. They remove metabolic waste products, toxins, and drugs. In addition, they limit inflammation by clearing cytokines and reduce immune cell activation by removing bacterial components. Dendritic cells (DCs) in the kidney maintain peripheral tolerance. About 85% of filtered water is reabsorbed by the proximal tubule, exposing distal nephron cells to high concentrations of low molecular weight antigens. These antigens are captured by DCs, helping to inactivate potentially autoreactive T cells and maintain tolerance to circulating antigens. In kidney failure, immune function is severely compromised due to the retention of toxins and cytokines, which activate immune cells and increase systemic inflammation. The kidneys are also vulnerable to immune-mediated diseases. Loss of immune homeostasis, characterized by over- or under-activity of the immune response, can adversely affect kidney function. With advances in immunology and cellular biology, biologic therapies targeting various pathways involved in the pathophysiology of kidney diseases are being developed. In this review, the immunologic aspects of kidney diseases and focus on cytokine-based therapies that may hold promise for the treatment of kidney diseases in the future will be presented.

Inflammation and all-cause mortality in patients undergoing peritoneal dialysis

OBJECTIVE

This study aimed to evaluate inflammatory biomarkers in patients undergoing peritoneal dialysis and investigate their association with all-cause mortality or transfer to hemodialysis.

METHODS

This prospective cohort study included 43 patients undergoing peritoneal dialysis. Plasma levels of cytokines were measured using flow cytometry and capture enzyme-linked immunosorbent assay. Biomarkers were categorized based on their respective median values. Survival analysis was conducted using the Kaplan-Meier estimator, considering two outcomes: all-cause mortality and transfer to hemodialysis.

RESULTS

After adjusting for confounding factors, plasma levels above the median of the levels of CCL2 and plasma, as well as below the median of TNF-α, and the median of dialysate IL-17 levels, were associated with an increased risk of experiencing the specified outcomes after approximately 16 months of follow-up.

CONCLUSION

These findings suggest that inflammatory biomarkers may be a valuable tool for predicting all-cause mortality and transfer to hemodialysis in patients undergoing peritoneal dialysis.

Beta-adrenergic signaling and T-lymphocyte-produced catecholamines are necessary for interleukin 17A synthesis

Background

Post-traumatic stress disorder (PTSD) is a debilitating psychological disorder that also presents with neuroimmune irregularities. Patients display elevated sympathetic tone and are at an increased risk of developing secondary autoimmune diseases. Previously, using a preclinical model of PTSD, we demonstrated that elimination of sympathetic signaling to T-lymphocytes specifically limited their ability to produce pro-inflammatory interleukin 17A (IL-17A); a cytokine implicated in the development of many autoimmune disorders. However, the mechanism linking sympathetic signaling to T-lymphocyte IL-17A production remained unclear.

Methods

Using a modified version of repeated social defeat stress (RSDS) that allows for both males and females, we assessed the impact of adrenergic receptor blockade (genetically and pharmacologically) and catecholamine depletion on T-lymphocyte IL-17A generation. Additionally, we explored the impact of adrenergic signaling and T-lymphocyte-produced catecholamines on both CD4+ and CD8+ T-lymphocytes polarized to IL-17A-producing phenotypes ex vivo.

Results

Only pharmacological inhibition of the beta 1 and 2 adrenergic receptors (β1/2) significantly decreased circulating IL-17A levels after RSDS, but did not impact other pro-inflammatory cytokines (e.g., IL-6, TNF-α, and IL-10). This finding was confirmed using RSDS with both global β1/2 receptor knock-out mice, as well as by adoptively transferring β1/2 knock-out T-lymphocytes into immunodeficient hosts. Furthermore, ex vivo polarized T-lymphocytes produced significantly less IL-17A with the blockade of β1/2 signaling, even in the absence of exogenous sympathetic neurotransmitter supplementation, which suggested T-lymphocyte-produced catecholamines may be involved in IL-17A production. Indeed, pharmacological depletion of catecholamines both in vivo and ex vivo abrogated T-lymphocyte IL-17A production demonstrating the importance of immune-generated neurotransmission in pro-inflammatory cytokine generation.

Conclusions

Our data depict a novel role for β1/2 adrenergic receptors and autologous catecholamine signaling during T-lymphocyte IL-17A production. These findings provide a new target for pharmacological therapy in both psychiatric and autoimmune diseases associated with IL-17A-related pathology.

Immune cells and hypertension

Hypertension is one of the leading causes of death due to target organ injury from cardiovascular disease. Although there are many treatments, only one-sixth of hypertensive patients effectively control their blood pressure. Therefore, further understanding the pathogenesis of hypertension is essential for the treatment of hypertension. Much research shows that immune cells play an important role in the pathogenesis of hypertension. Here, we discuss the roles of different immune cells in hypertension. Many immune cells participate in innate and adaptive immune responses, such as monocytes/macrophages, neutrophils, dendritic cells, NK cells, and B and T lymphocytes. Immune cells infiltrate the blood vessels, kidneys, and hearts and cause damage. The mechanism is that immune cells secrete cytokines such as interleukin, interferon, and tumor necrosis factor, which affect the inflammatory reaction, oxidative stress, and kidney sodium water retention, and finally aggravate or reduce the dysfunction, remodeling, and fibrosis of the blood vessel, kidney, and heart to participate in blood pressure regulation. This article reviews the research progress on immune cells and hypertension.

A Decade of Pathogenesis Advances in Non-Type 2 Inflammatory Endotypes in Chronic Rhinosinusitis: 2012-2022

Chronic rhinosinusitis (CRS) is a heterogeneous disease characterized by localized inflammation of the upper airways. CRS includes two main phenotypes, namely, CRS with nasal polyps and CRS without nasal polyps. The phenotype-based classification method cannot reflect the pathological mechanism. The endotype-based classification method has been paid more and more attention by researchers. It is mainly divided into type 2 and non-type 2 endotypes. The mechanism driving the pathogenesis of non-type 2 inflammation is currently unknown. In this review, the PubMed and Web of Science databases were searched to conduct a critical analysis of representative literature works on the pathogenesis of non-type 2 inflammation in CRS published in the past decade. This review summarizes the latest evidence that may lead to the pathogenesis of non-type 2 inflammation. It is the main method that analyzing the pathogenesis from the perspective of immunology. Genomics and proteomics technique provide new approaches to the study of the pathogenesis. Due to differences in race, environment, geography, and living habits, there are differences in the occurrence of non-type 2 inflammation, which increase the difficulty of understanding the pathogenesis of non-type 2 inflammation in CRS. Studies have confirmed that non-type 2 endotype is more common in Asian patients. The emergence of overlap and unclassified endotypes has promoted the study of heterogeneity in CRS. In addition, as the source of inflammatory cells and the initiation site of the inflammatory response, microvessels and microlymphatic vessels in the nasal mucosal subepithelial tissue participate in the inflammatory response and tissue remodeling. It is uncertain whether CRS patients affect the risk of infection with SARS-CoV-2. In addition, the pathophysiological mechanism of non-type 2 CRS combined with COVID-19 remains to be further studied, and it is worth considering how to select the befitting biologics for CRS patients with non-type 2 inflammation.

Role of IL-17A in different stages of ischemic stroke

Interleukin-17A (IL-17A) plays an important role in the progression of ischemic stroke. IL-17A mediates the endothelial inflammatory response, promotes water and sodium retention, and changes the electrophysiological structure of the atrium, accelerating the progression of ischemic stroke risk factors such as atherosclerotic plaques, hypertension, and atrial fibrillation. In the acute phase of ischemic stroke, IL-17A mediates neuronal injury through neutrophil chemotaxis to the site of injury, the induction of neuronal apoptosis, and activation of the calpain-TRPC-6 (transient receptor potential channel-6) pathway. During ischemic stroke recovery, IL-17A, which is mainly derived from reactive astrocytes, promotes and maintains the survival of neural precursor cells (NPCs) in the subventricular zone (SVZ), neuronal differentiation, and synapse formation and participates in the repair of neurological function. Therapies targeting IL-17A-associated inflammatory signaling pathways can reduce the risk of ischemic stroke and neuronal damage and are a new therapeutic strategy for ischemic stroke and its risk factors. In this paper, we will briefly discuss the pathophysiological role of IL-17A in ischemic stroke risk factors, acute and chronic inflammatory responses, and the potential therapeutic value of targeting IL-17A.

Kidney microRNA Expression Pattern in Type 2 Diabetic Nephropathy in BTBR Ob/Ob Mice

Diabetic nephropathy (DN) is the main leading cause of chronic kidney disease worldwide. Although remarkable therapeutic advances have been made during the last few years, there still exists a high residual risk of disease progression to end-stage renal failure. To further understand the pathogenesis of tissue injury in this disease, by means of the Next-Generation Sequencing, we have studied the microRNA (miRNA) differential expression pattern in kidneys of Black and Tan Brachyury (BTBR) ob/ob (leptin deficiency mutation) mouse. This experimental model of type 2 diabetes and obesity recapitulates the key histopathological features described in advanced human DN and therefore can provide potential useful translational information. The miRNA-seq analysis, performed in the renal cortex of 22-week-old BTBR ob/ob mice, pointed out a set of 99 miRNAs significantly increased compared to non-diabetic, non-obese control mice of the same age, whereas no miRNAs were significantly decreased. Among them, miR-802, miR-34a, miR-132, miR-101a, and mir-379 were the most upregulated ones in diabetic kidneys. The in silico prediction of potential targets for the 99 miRNAs highlighted inflammatory and immune processes, as the most relevant pathways, emphasizing the importance of inflammation in the pathogenesis of kidney damage associated to diabetes. Other identified top canonical pathways were adipogenesis (related with ectopic fatty accumulation), necroptosis (an inflammatory and regulated form of cell death), and epithelial-to-mesenchymal transition, the latter supporting the importance of tubular cell phenotype changes in the pathogenesis of DN. These findings could facilitate a better understanding of this complex disease and potentially open new avenues for the design of novel therapeutic approaches to DN.