Overexpression of secretory leukocyte peptidase inhibitor (SLPI) does not modulate experimental osteoarthritis but may be a biomarker for the disease

Alarming serum antiprotease levels in axial spondyloarthritis

Objectives

The objective was to assess the serum levels of secretory leukocyte protease inhibitor (SLPI) and elafin in individuals diagnosed with axial spondyloarthritis (AxSpA) and analyze their diagnostic significance and correlation with disease activity.

Patients and methods

The case-controlled, cross-sectional study was conducted between August 2021 and April 2023. Sixty patients diagnosed with AxSpA (n=60) were classified according to imaging results as nonradiographic AxSpA (nr-AxSpA [n=30]; 15 males, 15 females; median age: 30 years; range, 27.6 to 34.1 years) and radiographic AxSpA (r-AxSpA [n=30]; 19 males, 11 females; median age: 33 years; range, 30.6 to 38.1 years), forming two patient groups (the nr-axSpA and r-axSpA groups). A total of 30 age- and sex-matched healthy controls (16 females, 14 males; median age: 33 years; range, 29.2 to 37.1 years) were included. Demographic data, laboratory, and clinical characteristics of the participants were recorded.

Results

There was no significant difference between SLPI and elafin serum levels in the disease groups. SLPI and elafin levels in AxSpA and nr-AxSpA groups were significantly higher compared to the control group (p<0.05). Based on receiver operating characteristic analysis, the diagnostic values of both parameters were found to be significant in the Ax-SpA and nr-AxSpA groups (p<0.05). There was no significant correlation between serum levels of SLPI and elafin and disease activity parameters. Significant positive correlations were found between SLPI and elafin in both the nr-AxSpA (p<0.05, r=0.870) and r-AxSpA (p<0.05, r=0.725) groups.

Conclusion

The levels of SLPI and elafin were found to be significantly elevated in patients with AxSpA, particularly in those with nr-AxSpA, compared to the control group. Therefore, SLPI and elafin can be used as therapeutic biomarkers for the diagnosis of AxSpA and nr-AxSpA. However, no relationship was found with disease activity.

The secretory leukocyte protease inhibitor (SLPI) in pathophysiology of non-communicable diseases: Evidence from experimental studies to clinical applications

Non-communicable diseases (NCDs) are a worldwide health issue because of their prevalence, negative impacts on human welfare, and economic costs. Protease enzymes play important roles in viral and NCD diseases. Slowing disease progression by inhibiting proteases using small-molecule inhibitors or endogenous inhibitory peptides appears to be crucial. Secretory leukocyte protease inhibitor (SLPI), an inflammatory serine protease inhibitor, maintains protease/antiprotease balance. SLPI is produced by host defense effector cells during inflammation to prevent proteolytic enzyme-induced tissue damage. The etiology of noncommunicable illnesses is linked to SLPI's immunomodulatory and tissue regeneration roles. Disease phases are associated with SLPI levels and activity changes in regional tissue and circulation. SLPI has been extensively evaluated in inflammation, but rarely in NCDs. Unfortunately, the thorough evaluation of SLPI's pathophysiological functions in NCDs in multiple research models has not been published elsewhere. In this review, data from PubMed from 2014 to 2023 was collected, analysed, and categorized into in vitro, in vivo, and clinical studies. According to the review, serine protease inhibitor (SLPI) activity control is linked to non-communicable diseases (NCDs) and other illnesses. Overexpression of the SLPI gene and protein may be a viable diagnostic and therapeutic target for non-communicable diseases (NCDs). SLPI is also cytoprotective, making it a unique treatment. These findings suggest that future research should focus on these pathways using advanced methods, reliable biomarkers, and therapy approaches to assess susceptibility and illness progression. Implications from this review will help pave the way for a new therapeutic target and diagnosis marker for non-communicable diseases.

Prokineticin 2 is a catabolic regulator of osteoarthritic cartilage destruction in mouse

BACKGROUND

Our preliminary study indicates that the multi-functional protein, prokineticin 2 (Prok2), is upregulated in osteoarthritic (OA) chondrocytes as a target of the hypoxia-inducible factor (HIF)-2α. This study aims to elucidate the potential roles of Prok2 in OA.

METHODS

Prok2 expression was assessed through microarray analysis in chondrocytes and confirmed via immunostaining in OA cartilage. Experimental OA was induced through destabilization of the medial meniscus (DMM). Functions of Prok2 were assessed by adenoviral overexpression, intra-articular (IA) injection of recombinant Prok2 (rProk2), and knockdown of Prok2 in joint tissues. We also explored the potential utility of Prok2 as an OA biomarker using enzyme-linked immunosorbent assay (ELISA).

RESULTS

HIF-2α upregulated Prok2, one of the prokineticin signaling components, in OA chondrocytes of mice and humans. Adenoviral overexpression of Prok2 in chondrocytes and cartilage explants, as well as the application of rProk2, led to an upregulation of matrix metalloproteinase (MMP)3 and MMP13. Consistently, the overexpression of Prok2 in joint tissues or IA injection of rProk2 exacerbated cartilage destruction and hindpaw mechanical allodynia induced by DMM. However, the knockdown of Prok2 in joint tissues did not significantly affect DMM-induced cartilage destruction. Additionally, despite being a secreted protein, the serum levels of Prok2 in OA mice and human OA patients were found to be below the range detected by ELISA.

CONCLUSION

The upregulation of Prok2 exacerbates OA cartilage destruction and hindpaw mechanical allodynia. However, its knockdown is not sufficient to inhibit experimental OA and Prok2 is not a potential candidate serum biomarker of OA.

Function and regulation of nuclear factor 1 X-type on chondrocyte proliferation and differentiation

Nuclear factor 1 X-type (Nfix) is a transcription factor related to mental and physical development. However, very few studies have reported the effects of Nfix on cartilage. This study aims to reveal the influence of Nfix on the proliferation and differentiation of chondrocytes, and to explore its potential action mechanism. We isolated primary chondrocytes from the costal cartilage of newborn C57BL/6 mice and with Nfix overexpression or silencing treatment. We used Alcian blue staining and found that Nfix overexpression significantly promoted ECM synthesis in chondrocytes while silencing inhibited ECM synthesis. Using RNA-seq technology to study the expression pattern of Nfix in primary chondrocytes. We found that Nfix overexpression significantly up-regulated genes that are related to chondrocyte proliferation and extracellular matrix (ECM) synthesis and significantly down-regulated genes related to chondrocyte differentiation and ECM degradation. Nfix silencing, however, significantly up-regulated genes associated with cartilage catabolism and significantly down-regulated genes associated with cartilage growth promotion. Furthermore, Nfix exerted a positive regulatory effect on Sox9, and we propose that Nfix may promote chondrocyte proliferation and inhibit differentiation by stimulating Sox9 and its downstream genes. Our findings suggest that Nfix may be a potential target for the regulation of chondrocyte proliferation and differentiation.

STING mediates experimental osteoarthritis and mechanical allodynia in mouse

BACKGROUND

This study was performed to develop therapeutic targets of osteoarthritis (OA) that can be targeted to alleviate OA development (i.e., cartilage destruction) and relieve the OA-associated joint pain.

METHODS

The candidate molecule, STING (stimulator of interferon genes, encoded by Sting1), was identified by microarray analysis of OA-like mouse chondrocytes. Experimental OA in mice was induced by destabilization of the medial meniscus (DMM). STING functions in OA and hindpaw mechanical allodynia were evaluated by gain-of-function (intra-articular injection of a STING agonist) and loss-of-function (Sting1-/- mice) approaches.

RESULTS

DNA damage was observed in OA-like chondrocytes. Cytosolic DNA sensors, STING and its upstream molecule, cGAS (cyclic GMP-AMP synthase), were upregulated in OA chondrocytes and cartilage of mouse and human. Genetic ablation of STING in mice (Sting1-/-) alleviated OA manifestations (cartilage destruction and subchondral bone sclerosis) and hindpaw mechanical allodynia. In contrast, stimulation of STING signaling in joint tissues by intra-articular injection of cGAMP exacerbated OA manifestations and mechanical sensitization. Mechanistic studies on the regulation of hindpaw mechanical allodynia revealed that STING regulates the expression of peripheral sensitization molecules in the synovium and meniscus of mouse knee joints.

CONCLUSION

Our results indicated that STING, which senses damaged cytosolic DNA and accordingly activates the innate immune response, regulates OA pathogenesis and hindpaw mechanical allodynia. Therefore, inhibition of STING could be a therapeutic approach to inhibit OA cartilage destruction and relieve the associated mechanical sensitization in model mice.

Exploring the role of differentially expressed metabolic genes and their mechanisms in bone metastatic prostate cancer

Background

Approximately 10-20% of patients diagnosed with prostate cancer (PCa) evolve into castration-resistant prostate cancer (CRPC), while nearly 90% of patients with metastatic CRPC (mCRPC) exhibit osseous metastases (BM). These BM are intimately correlated with the stability of the tumour microenvironment.

Purpose

This study aspires to uncover the metabolism-related genes and the underlying mechanisms responsible for bone metastatic prostate cancer (BMPCa).

Methods

Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) datasets of PCa and BM were analyzed through R Studio software to identify differentially expressed genes (DEGs). The DEGs underwent functional enrichment via Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO), with key factors screened by a random forest utilized to establish a prognostic model for PCa. The study explored the relationship between DEGs and the stability of the immune microenvironment. The action and specificity of CRISP3 in PCa was validated through western blot analysis, CCK-8 assay, scratch assay, and cellular assay.

Results

The screening of GEO and TCGA datasets resulted in the identification of 199 co-differential genes. Three DEGs, including DES, HBB, and SLPI, were selected by random forest classification model and cox regression model. Immuno-infiltration analysis disclosed that a higher infiltration of naïve B cells and resting CD4 memory T cells occurred in the high-expression group of DES, whereas infiltration of resting M1 macrophages and NK cells was greater in the low-expression group of DES. A significant infiltration of neutrophils was observed in the high-expression group of HBB, while greater infiltration of gamma delta T cells and M1 macrophages was noted in the low-expression group of HBB. Resting dendritic cells, CD8 T cells, and resting T regulatory cells (Tregs) infiltrated significantly in the high-expression group of SLPI, while only resting mast cells infiltrated significantly in the low-expression group of SLPI. CRISP3 was established as a critical gene in BMPCa linked to DES expression. Targeting CRISP3, d-glucopyranose may impact tumour prognosis. During the mechanistic experiments, it was established that CRISP3 can advance the proliferation and metastatic potential of PCa by advancing epithelial-to-mesenchymal transition (EMT).

Conclusion

By modulating lipid metabolism and maintaining immunological and microenvironmental balance, DES, HBB, and SLPI suppress prostate cancer cell growth. The presence of DES-associated CRISP3 is a harbinger of unfavorable outcomes in prostate cancer and may escalate tumor proliferation and metastatic capabilities by inducing epithelial-mesenchymal transition.

Nfib promotes chondrocyte proliferation and inhibits differentiation by mildly regulating Sox9 and its downstream genes

BACKGROUND

Chondrocyte proliferation and differentiation play pivotal roles in regulating cartilage formation, endochondral bone formation, and repair. Cartilage damage and underdevelopment may cause severe joint diseases. Various transcription factors regulate cartilage development. Nuclear factor 1 B (Nfib) is a transcription factor that plays a regulatory role in various organs. However, the effect and mechanism of Nfib on the proliferation and differentiation of chondrocytes in cartilage are still largely unknown.

METHODS AND RESULTS

In the present study, we investigated the gene expression patterns in primary chondrocytes with Nfib overexpression or silencing by RNA sequencing (RNA-seq) technology. The results showed that Nfib overexpression significantly up-regulated genes that are related to chondrocyte proliferation and extracellular matrix (ECM) synthesis and significantly down-regulated genes related to chondrocyte differentiation and ECM degradation. However, with Nfib silencing, the genes involved in promoting chondrocyte differentiation were significantly up-regulated, whereas those involved in promoting chondrocyte proliferation were significantly down-regulated. Furthermore, quantitative real-time PCR (qRT-PCR), western blot, alcian blue staining and immunofluorescence staining assays further confirmed that Nfib potentially promotes chondrocyte proliferation and extracellular synthesis but inhibits differentiation.

CONCLUSIONS

The molecular mechanism of Nfib in promoting chondrocyte proliferation and inhibiting differentiation was probably achieved by stimulating Sox9 and its downstream genes. Thus, this study adds new insights regarding the underlying molecular mechanism of transcriptional regulation in cartilage.