Spleen fibroblastic reticular cell-derived acetylcholine promotes lipid metabolism to drive autoreactive B cell responses

Metabolic dysregulation of lymphocytes in autoimmune diseases

Lymphocytes are crucial for protective immunity against infection and cancers; however, immune dysregulation can lead to autoimmune diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Metabolic adaptation controls lymphocyte fate; thus, metabolic reprogramming can contribute to the pathogenesis of autoimmune diseases. Here, we summarize recent advances on how metabolic reprogramming determines the autoreactive and proinflammatory nature of lymphocytes in SLE and RA, unraveling molecular mechanisms and providing therapeutic targets for human autoimmune diseases.

Fibroblast: A Novel Target for Autoimmune and Inflammatory Skin Diseases Therapeutics

Fibroblasts are crucial components of the skin structure. They were traditionally believed to maintain the skin's structure by producing extracellular matrix and other elements. Recent research illuminated that fibroblasts can respond to external stimuli and exhibit diverse functions, such as the secretion of pro-inflammatory factors, adipogenesis, and antigen presentation, exhibiting remarkable heterogeneity and plasticity. This revelation positions fibroblasts as active contributors to the pathogenesis of skin diseases, challenging the traditional perspective that views fibroblasts solely as structural entities. Based on their diverse functions, fibroblasts can be categorized into six subtypes: pro-inflammatory fibroblasts, myofibroblasts, adipogenic fibroblasts, angiogenic fibroblasts, mesenchymal fibroblasts, and antigen-presenting fibroblasts. Cytokines, metabolism, and epigenetics regulate functional abnormalities in fibroblasts. The dynamic changes fibroblasts exhibit in different diseases and disease states warrant a comprehensive discussion. We focus on dermal fibroblasts' aberrant manifestations and pivotal roles in inflammatory and autoimmune skin diseases, including psoriasis, vitiligo, lupus erythematosus, scleroderma, and atopic dermatitis, and propose targeting aberrantly activated fibroblasts as a potential therapeutic strategy for inflammatory and autoimmune skin diseases.

Fatty acid oxidation in immune function

Cellular metabolism is a crucial determinant of immune cell fate and function. Extensive studies have demonstrated that metabolic decisions influence immune cell activation, differentiation, and cellular capacity, in the process impacting an organism's ability to stave off infection or recover from injury. Conversely, metabolic dysregulation can contribute to the severity of multiple disease conditions including autoimmunity, alloimmunity, and cancer. Emerging data also demonstrate that metabolic cues and profiles can influence the success or failure of adoptive cellular therapies. Importantly, immunometabolism is not one size fits all; and different immune cell types, and even subdivisions within distinct cell populations utilize different metabolic pathways to optimize function. Metabolic preference can also change depending on the microenvironment in which cells are activated. For this reason, understanding the metabolic requirements of different subsets of immune cells is critical to therapeutically modulating different disease states or maximizing cellular function for downstream applications. Fatty acid oxidation (FAO), in particular, plays multiple roles in immune cells, providing both pro- and anti-inflammatory effects. Herein, we review the major metabolic pathways available to immune cells, then focus more closely on the role of FAO in different immune cell subsets. Understanding how and why FAO is utilized by different immune cells will allow for the design of optimal therapeutic interventions targeting this pathway.

Zinc-Based ROS Amplifiers Trigger Cancer Chemodynamic/Ion Interference Therapy Through Self-Cascade Catalysis

Nanozyme-mediated chemodynamic therapy has emerged as a promising strategy due to its tumor specificity and controlled catalytic activity. However, the poor efficacy caused by low hydrogen peroxide (H2O2) levels in the tumor microenvironment (TME) poses challenges. Herein, an H2O2 self-supplying nanozyme is constructed through loading peroxide-like active platinum nanoparticles (Pt NPs) on zinc peroxide (ZnO2) (denoted as ZnO2@Pt). ZnO2 releases H2O2 in response to the acidic TME. Pt NPs catalyze the hydroxyl radical generation from H2O2 while reducing the mitigation of oxidative stress by glutathione, serving as a reactive oxygen (ROS) amplifier through self-cascade catalysis. In addition, Zn2+ released from ZnO2 interferes with tumor cell energy supply and metabolism, enabling ion interference therapy to synergize with chemodynamic therapy. In vitro studies demonstrate that ZnO2@Pt induces cellular oxidative stress injury through enhanced ROS generation and Zn2+ release, downregulating ATP and NAD+ levels. In vivo assessment of anticancer effects showed that ZnO2@Pt could generate ROS at tumor sites to induce apoptosis and downregulate energy supply pathways associated with glycolysis, resulting in an 89.7% reduction in tumor cell growth. This study presents a TME-responsive nanozyme capable of H2O2 self-supply and ion interference therapy, providing a paradigm for tumor-specific nanozyme design.

Dysregulated serum lipid profile is associated with inflammation and disease activity in primary Sjögren's syndrome: a retrospective study in China

PURPOSE

To investigate the relationship between the lipid profiles of patients with primary Sjögren's syndrome (pSS) and other clinical characteristics, laboratory examination, disease activity, and inflammatory factors. In addition, the risk factors for hyperlipidemia-related complications of pSS and the effect of hydroxychloroquine (HCQ) usage on the lipid profile were incorporated into this study.

METHODS

This is a single-center, retrospective study that included 367 patients who were diagnosed with pSS at Tongji Hospital, School of Medicine, Tongji University, China from January 2010 to March 2022. Initially, demographic information, clinical characteristics, medication records, and complications of the patients were gathered. A case-control analysis compared the 12 systems involvement (ESSDAI domain), clinical symptoms, and laboratory tests between pSS patients with and without dyslipidemia. A simple linear regression model was employed to investigate the relationship between serum lipid profile and inflammatory factors. Logistics regression analysis was performed to assess variables for hyperlipidemia-related complications of pSS. The paired t-test was then used to evaluate the improvement in lipid profile among pSS patients.

RESULTS

48.7 % of all pSS patients had dyslipidemia, and alterations in lipid levels were related to gender, age, and smoking status but not body mass index (BMI). Dyslipidemia is more prevalent in pSS patients who exhibit heightened autoimmunity and elevated levels of inflammation. Higher concentrations of multiple highly inflammatory factors correlate with a more severe form of dyslipidemia. Non-traditional cardiovascular risk factors may contribute to hyperlipidemia-related complications of pSS, such as increased, low complement 3 (C3) and low C4. According to our study, HCQ usage may protect against lipid-related disease in pSS.

CONCLUSION

Attention should be paid to the dyslipidemia of pSS. This research aims to clarify the population portrait of pSS patients with abnormal lipid profiles and provides insights into the correlation between metabolism and inflammation in individuals with pSS and the potential role they play in the advancement of the disease. These findings provide novel avenues for further understanding the underlying mechanisms of pSS pathogenesis.

C5a-C5aR1 axis controls mitochondrial fission to promote podocyte injury in lupus nephritis

Podocytes are essential to maintaining the integrity of the glomerular filtration barrier, but they are frequently affected in lupus nephritis (LN). Here, we show that the significant upregulation of Drp1S616 phosphorylation in podocytes promotes mitochondrial fission, leading to mitochondrial dysfunction and podocyte injury in LN. Inhibition or knockdown of Drp1 promotes mitochondrial fusion and protects podocytes from injury induced by LN serum. In vivo, pharmacological inhibition of Drp1 reduces the phosphorylation of Drp1S616 in podocytes in lupus-prone mice. Podocyte injury is reversed when Drp1 is inhibited, resulting in the alleviation of proteinuria. Mechanistically, complement component C5a (C5a) upregulates the phosphorylation of Drp1S616 and promotes mitochondrial fission in podocytes. Moreover, the expression of C5a receptor 1 (C5aR1) is notably upregulated in podocytes in LN. C5a-C5aR1 axis-controlled phosphorylation of Drp1S616 and mitochondrial fission are substantially suppressed when C5aR1 is knocked down by siRNA. Moreover, lupus-prone mice treated with C5aR inhibitor show reduced phosphorylation of Drp1S616 in podocytes, resulting in significantly less podocyte damage. Together, this study uncovers a novel mechanism by which the C5a-C5aR1 axis promotes podocyte injury by enhancing Drp1-mediated mitochondrial fission, which could have significant implications for the treatment of LN.

Brain-Splenic Immune System Interactions in Hypertension: Cellular and Molecular Mechanisms

Hypertension represents a major worldwide cause of death and disability, and it is becoming increasingly clear that available therapies are not sufficient to reduce the risk of major cardiovascular events. Various mechanisms contribute to blood pressure increase: neurohormonal activation, autonomic nervous system imbalance, and immune activation. Of note, the brain is an important regulator of blood pressure levels; it recognizes the peripheral perturbation and organizes a reflex response by modulating immune system and hormonal release to attempt at restoring the homeostasis. The connection between the brain and peripheral organs is mediated by the autonomic nervous system, which also modulates immune and inflammatory responses. Interestingly, an increased autonomic nervous system activity has been correlated with an altered immune response in cardiovascular diseases. The spleen is the largest immune organ exerting a potent influence on the cardiovascular system during disease and is characterized by a dense noradrenergic innervation. Taken together, these aspects led to hypothesize a key role of neuroimmune mechanisms in the onset and progression of hypertension. This review discusses how the nervous and splenic immune systems interact and how the mechanisms underlying the neuroimmune cross talk influence the disease progression.

Pharmacological and Electroceutical Targeting of the Cholinergic Anti-Inflammatory Pathway in Autoimmune Diseases

Continuous dialogue between the immune system and the brain plays a key homeostatic role in various immune responses to environmental cues. Several functions are under the control of the vagus nerve-based inflammatory reflex, a physiological mechanism through which nerve signals regulate immune functions. In the cholinergic anti-inflammatory pathway, the vagus nerve, its pivotal neurotransmitter acetylcholine, together with the corresponding receptors play a key role in modulating the immune response of mammals. Through communications of peripheral nerves with immune cells, it modulates proliferation and differentiation activities of various immune cell subsets. As a result, this pathway represents a potential target for treating autoimmune diseases characterized by overt inflammation and a decrease in vagal tone. Consistently, converging observations made in both animal models and clinical trials revealed that targeting the cholinergic anti-inflammatory pathway using pharmacologic approaches can provide beneficial effects. In parallel, bioelectronic medicine has recently emerged as an alternative approach to managing systemic inflammation. In several studies, nerve electrostimulation was reported to be clinically relevant in reducing chronic inflammation in autoimmune diseases, including rheumatoid arthritis and diabetes. In the future, these new approaches could represent a major therapeutic strategy for autoimmune and inflammatory diseases.

Neurotransmitters arrive to control systemic autoimmunity

Immune cell microenvironment plays a major role in the aberrant function of immune cells in systemic lupus erythematosus. Zeng and co-authors show that in human and murine lupus, splenic stromal cell-derived acetylcholine switches B cell metabolism to fatty acid oxidation and promotes B cell autoreactivity and disease development.