High temperature requirement factor A1 (HTRA1) regulates the activation of latent TGF-β1 in keloid fibroblasts

Progress in the Study of the Role and Mechanism of HTRA1 in Diseases Related to Vascular Abnormalities

High temperature requirement A1 (HTRA1) is a member of the serine protease family, comprising four structural domains: IGFBP domain, Kazal domain, protease domain and PDZ domain. HTRA1 encodes a serine protease, a secreted protein that is widely expressed in the vasculature. HTRA1 regulates a wide range of physiological processes through its proteolytic activity, and is also involved in a variety of vascular abnormalities-related diseases. This article reviews the role of HTRA1 in the development of vascular abnormalities-related hereditary cerebral small vessel disease (CSVD), age-related macular degeneration (AMD), tumors and other diseases. Through relevant research advances to understand the role of HTRA1 in regulating signaling pathways or refolding, translocation, degradation of extracellular matrix (ECM) proteins, thus directly or indirectly regulating angiogenesis, vascular remodeling, and playing an important role in vascular homeostasis, further understanding the mechanism of HTRA1's role in vascular abnormality-related diseases is important for HTRA1 to be used as a therapeutic target in related diseases.

The relationship between TGF-β1 and cognitive function in the brain

Transforming growth factor-β1 (TGF-β1), a multifunctional cytokine, plays a pivotal role in synaptic formation, plasticity, and neurovascular unit regulation. This review highlights TGF-β1's potential impact on cognitive function, particularly in the context of neurodegenerative disorders. However, despite the growing body of evidence, a comprehensive understanding of TGF-β1's precise role remains elusive. Further research is essential to unravel the complex mechanisms through which TGF-β1 influences cognitive function and to explore therapeutic avenues for targeting TGF-β1 in neurodegenerative conditions. This investigation sheds light on TGF-β1's contribution to cognitive function and offers prospects for innovative treatments and interventions. This review delves into the intricate relationship between TGF-β1 and cognitive function.

Development and validation of risk prediction and neural network models for dilated cardiomyopathy based on WGCNA

Background

Dilated cardiomyopathy (DCM) is a progressive heart condition characterized by ventricular dilatation and impaired myocardial contractility with a high mortality rate. The molecular characterization of DCM has not been determined yet. Therefore, it is crucial to discover potential biomarkers and therapeutic options for DCM.

Methods

The hub genes for the DCM were screened using Weighted Gene Co-expression Network Analysis (WGCNA) and three different algorithms in Cytoscape. These genes were then validated in a mouse model of doxorubicin (DOX)-induced DCM. Based on the validated hub genes, a prediction model and a neural network model were constructed and validated in a separate dataset. Finally, we assessed the diagnostic efficiency of hub genes and their relationship with immune cells.

Results

A total of eight hub genes were identified. Using RT-qPCR, we validated that the expression levels of five key genes (ASPN, MFAP4, PODN, HTRA1, and FAP) were considerably higher in DCM mice compared to normal mice, and this was consistent with the microarray results. Additionally, the risk prediction and neural network models constructed from these genes showed good accuracy and sensitivity in both the combined and validation datasets. These genes also demonstrated better diagnostic power, with AUC greater than 0.7 in both the combined and validation datasets. Immune cell infiltration analysis revealed differences in the abundance of most immune cells between DCM and normal samples.

Conclusion

The current findings indicate an underlying association between DCM and these key genes, which could serve as potential biomarkers for diagnosing and treating DCM.

Heterozygous Pathogenic and Likely Pathogenic Symptomatic HTRA1 Variant Carriers in Cerebral Small Vessel Disease

High temperature requirement serine peptidase A1 (HTRA1) related cerebral small vessel disease (CSVD) includes both symptomatic heterozygous HTRA1 variant carrier and cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL) patients. Presently, most reported symptomatic heterozygous HTRA1 variant carrier cases are sporadic family reports with a lack of specific characteristics. Additionally, the molecular mechanism of heterozygous HTRA1 gene variants is unclear. We conducted this review to collect symptomatic carriers of heterozygous HTRA1 gene variants reported as of 2022, analyzed all pathogenicity according to American College of Medical Genetics and Genomics (ACMG) variant classification, and summarized the cases with pathogenic and likely pathogenic HTRA1 variants gender characteristics, age of onset, geographical distribution, initial symptoms, clinical manifestations, imaging signs, HTRA1 gene variant information and to speculate its underlying pathogenic mechanisms. In this review, we summarized the following characteristics of pathogenic and likely pathogenic symptomatic HTRA1 variant carriers: to date, the majority of reported symptomatic HTRA1 carriers are in European and Asian countries, particularly in China which was found to have the highest number of reported cases. The age of first onset is mostly concentrated in the fourth and fifth decades. The heterozygous HTRA1 gene variants were mostly missense variants. The two variant sites, 166-182 aa and 274-302 aa, were the most concentrated. Clinicians need to pay attention to de novo data and functional data, which may affect the pathogenicity analysis. The decrease in HtrA1 protease activity is currently the most important explanation for the genetic pathogenesis.

An updated review of the immunological mechanisms of keloid scars

Keloid is a type of disfiguring pathological scarring unique to human skin. The disorder is characterized by excessive collagen deposition. Immune cell infiltration is a hallmark of both normal and pathological tissue repair. However, the immunopathological mechanisms of keloid remain unclear. Recent studies have uncovered the pivotal role of both innate and adaptive immunity in modulating the aberrant behavior of keloid fibroblasts. Several novel therapeutics attempting to restore regulation of the immune microenvironment have shown variable efficacy. We review the current understanding of keloid immunopathogenesis and highlight the potential roles of immune pathway-specific therapeutics.

Current Perspectives on Nucleus Pulposus Fibrosis in Disc Degeneration and Repair

A growing body of evidence in humans and animal models indicates an association between intervertebral disc degeneration (IDD) and increased fibrotic elements in the nucleus pulposus (NP). These include enhanced matrix turnover along with the abnormal deposition of collagens and other fibrous matrices, the emergence of fibrosis effector cells, such as macrophages and active fibroblasts, and the upregulation of the fibroinflammatory factors TGF-β1 and IL-1/-13. Studies have suggested a role for NP cells in fibroblastic differentiation through the TGF-βR1-Smad2/3 pathway, inflammatory activation and mechanosensing machineries. Moreover, NP fibrosis is linked to abnormal MMP activity, consistent with the role of matrix proteases in regulating tissue fibrosis. MMP-2 and MMP-12 are the two main profibrogenic markers of myofibroblastic NP cells. This review revisits studies in the literature relevant to NP fibrosis in an attempt to stratify its biochemical features and the molecular identity of fibroblastic cells in the context of IDD. Given the role of fibrosis in tissue healing and diseases, the perspective may provide new insights into the pathomechanism of IDD and its management.

The multifaced role of HtrA1 in the development of joint and skeletal disorders

HtrA1 (High temperature requirement A1) family proteins include four members, widely conserved from prokaryotes to eukaryotes, named HtrA1, HtrA2, HtrA3 and HtrA4. HtrA1 is a serine protease involved in a variety of biological functions regulating many signaling pathways degrading specific components and playing key roles in many human diseases such as neurodegenerative disorders, pregnancy complications and cancer. Due to its role in the breakdown of many ExtraCellular Matrix (ECM) components of articular cartilage such as fibronectin, decorin and aggrecan, HtrA1 encouraged many researches on studying its role in several skeletal diseases (SDs). These studies were further inspired by the fact that HtrA1 is able to regulate the signaling of one of the most important cytokines involved in SDs, the TGFβ-1. This review aims to summarize the data currently available on the role of HtrA1 in skeletal diseases such as Osteoporosis, Rheumatoid Arthritis, Osteoarthritis and Intervertebral Disc Degeneration (IDD). The use of HtrA1 as a marker of frailty in geriatric medicine would represent a powerful tool for identifying older individuals at risk of developing skeletal disorders, evaluating an appropriate intervention to improve quality care in these people avoiding or improving age-related SDs in the elderly population.

HTRA1 Variants and the Interaction with Smoking Confer the Genetic Susceptibility to Ischemic Stroke

High temperature requirement protein A1 (HtrA1) was identified as the causative gene of autosomal recessive arteriopathy and associated with lacunar ischemic stroke (IS) in European. This study aimed at evaluating the association of HTRA1 with IS and four tagging single-nucleotide polymorphisms (SNPs) were genotyped in a cohort of 4,098 Chinese. The mRNA level of HTRA1 in 72 IS cases and 72 hypertension controls were measured and compared. In whole population, SNP rs2268350 (C>T) was significantly associated with IS incidence (P=0.034). Stratification analysis observed significant association of rs2268350 in male, smoking and drinking populations, rs2672587 (C>G) in smoking and nonsmoking populations and rs3793917 (C>G) in smoking, nonsmoking and nondrinking populations with stroke respectively (P<0.05). The additive interaction and multiplicative interaction between rs2268350 and smoking were both of significant (P<0.05) after adjustment for the covariates. There was a cumulated risk of IS among genotypes of rs3793917 (P=0.009) and rs2672587 (P=0.047) in smoking population. The mRNA level of HTRA1 in non-smokers with rs2268350 CC was significantly higher than smokers with rs2268350 CT/TT (P=0.046) in IS cases. Our findings support that HTRA1 confers the genetic susceptibility to IS and smoking might modify the genetic effect of HTRA1 on IS by suppressing HTRA1 mRNA expression.