Autophagy is involved in the sclerotic phase of systemic sclerosis

The multifaceted role of autophagy in skin autoimmune disorders: a guardian or culprit?

Autophagy is a cellular process that functions to maintain intracellular homeostasis via the degradation and recycling of defective organelles or damaged proteins. This dynamic mechanism participates in various biological processes, such as the regulation of cellular differentiation, proliferation, survival, and the modulation of inflammation and immune responses. Recent evidence has demonstrated the involvement of polymorphisms in autophagy-related genes in various skin autoimmune diseases. In addition, autophagy, along with autophagy-related proteins, also contributes to homeostasis maintenance and immune regulation in the skin, which is associated with skin autoimmune disorders. This review aims to provide an overview of the multifaceted role of autophagy in skin autoimmune diseases and shed light on the potential of autophagy-targeting therapeutic strategies in dermatology.

TMEM175: A lysosomal ion channel associated with neurological diseases

Lysosomes are acidic intracellular organelles with autophagic functions that are critical for protein degradation and mitochondrial homeostasis, while abnormalities in lysosomal physiological functions are closely associated with neurological disorders. Transmembrane protein 175 (TMEM175), an ion channel in the lysosomal membrane that is essential for maintaining lysosomal acidity, has been proven to coordinate with V-ATPase to modulate the luminal pH of the lysosome to assist the digestion of abnormal proteins and organelles. However, there is considerable controversy about the characteristics of TMEM175. In this review, we introduce the research progress on the structural, modulatory, and functional properties of TMEM175, followed by evidence of its relevance for neurological disorders. Finally, we discuss the potential value of TMEM175 as a therapeutic target in the hope of providing new directions for the treatment of neurodegenerative diseases.

The Role of Autophagy and Apoptosis in Affected Skin and Lungs in Patients with Systemic Sclerosis

Systemic sclerosis (SSc) is a complex autoimmune inflammatory disorder with multiple organ involvement. Skin changes present the hallmark of SSc and coincide with poor prognosis. Interstitial lung diseases (ILD) are the most widely reported complications in SSc patients and the primary cause of death. It has been proposed that the processes of autophagy and apoptosis could play a significant role in the pathogenesis and clinical course of different autoimmune diseases, and accordingly in SSc. In this manuscript, we review the current knowledge of autophagy and apoptosis processes in the skin and lungs of patients with SSc. Profiling of markers involved in these processes in skin cells can be useful to recognize the stage of fibrosis and can be used in the clinical stratification of patients. Furthermore, the knowledge of the molecular mechanisms underlying these processes enables the repurposing of already known drugs and the development of new biological therapeutics that aim to reverse fibrosis by promoting apoptosis and regulate autophagy in personalized treatment approach. In SSc-ILD patients, the molecular signature of the lung tissues of each patient could be a distinctive criterion in order to establish the correct lung pattern, which directly impacts the course and prognosis of the disease. In this case, resolving the role of tissue-specific markers, which could be detected in the circulation using sensitive molecular methods, would be an important step toward development of non-invasive diagnostic procedures that enable early and precise diagnosis and preventing the high mortality of this rare disease.

Effects of Immunoglobulins G From Systemic Sclerosis Patients in Normal Dermal Fibroblasts: A Multi-Omics Study

Autoantibodies (Aabs) are frequent in systemic sclerosis (SSc). Although recognized as potent biomarkers, their pathogenic role is debated. This study explored the effect of purified immunoglobulin G (IgG) from SSc patients on protein and mRNA expression of dermal fibroblasts (FBs) using an innovative multi-omics approach. Dermal FBs were cultured in the presence of sera or purified IgG from patients with diffuse cutaneous SSc (dcSSc), limited cutaneous SSc or healthy controls (HCs). The FB proteome and transcriptome were explored using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) and microarray assays, respectively. Proteomic analysis identified 3,310 proteins. SSc sera and purified IgG induced singular protein profile patterns. These FB proteome changes depended on the Aab serotype, with a singular effect observed with purified IgG from anti-topoisomerase-I autoantibody (ATA) positive patients compared to HC or other SSc serotypes. IgG from ATA positive SSc patients induced enrichment in proteins involved in focal adhesion, cadherin binding, cytosolic part, or lytic vacuole. Multi-omics analysis was performed in two ways: first by restricting the analysis of the transcriptomic data to differentially expressed proteins; and secondly, by performing a global statistical analysis integrating proteomics and transcriptomics. Transcriptomic analysis distinguished 764 differentially expressed genes and revealed that IgG from dcSSc can induce extracellular matrix (ECM) remodeling changes in gene expression profiles in FB. Global statistical analysis integrating proteomics and transcriptomics confirmed that IgG from SSc can induce ECM remodeling and activate FB profiles. This effect depended on the serotype of the patient, suggesting that SSc Aab might play a pathogenic role in some SSc subsets.