Neutrophils-derived Spink7 as one safeguard against experimental murine colitis

The antiprotease Spink7 promotes inflammation resolution by modulating multiple proteases activities during wound healing

BACKGROUND

Effective control of inflammation is crucial for the healing of cutaneous wounds, but the molecular mechanisms governing inflammation resolution during wound closure are still not yet clear. Here, we describe a homeostatic mechanism that facilitates the inflammation resolution by timely regulating the targeted proteases activities through antiprotease Spink7 (serine peptidase inhibitor, kazal type 7).

METHODS

The expression pattern of Spink7 was investigated by quantitative RT-PCR, immunohistochemistry (IHC) and in situ hybridization. In both Spink7 knockdown and knockout models, quantitative comparisons were made between the healing rate of wounds and histopathological morphometric analysis. Microarrays, multiple chemokine assays, IHC, immunofluorescence, protease activity measurement were performed to explore the underlying mechanisms of Spink7 knockout in impaired wound healing. Radiation-wound combined injury (R-W-CI) model was employed to evaluate the therapeutic effects of Spink7 manipulation.

RESULTS

Our study demonstrates that Spink7 is significantly upregulated in the differentiated epidermal granular keratinocytes of proliferative phase during murine wound closure. Both local knockdown of Spink7 levels in wounds using siRNA gel and systemic knockout of Spink7 using KO mice resulted in delayed wound closure with sustained neutrophil infiltration. Loss of Spink7 leads to augmented inflammatory responses, increased production of multiple chemokines/cytokines, and impaired M2 polarization of macrophages in wound healing. Furthermore, loss of Spink7 results in elevated proteolytic activities of uPA, MMP2/9 and KLK5/7 in proliferative phase. However, inhibiting KLK5/7 downstream PAR2 activation exacerbates the phenotype of KO mice. In R-W-CI model, further significant induction of Spink7 is observed in wounds with insufficient inflammatory response. Local suppression of Spink7 promotes wound healing in the R-W-CI model by augmenting inflammation.

CONCLUSIONS

Maintaining an endogenous balance between Spink7 and its target proteases is a crucial checkpoint for regulating inflammation resolution during healing. Therefore, manipulating levels of Spink7 might be an effective treatment for impaired wounds caused by inflammatory dysregulation.

ECRG2/SPINK7 Tumor Suppressor as Modulator of DNA Damage Response

Esophageal Cancer-Related Gene 2 (ECRG2), also known as Serine Peptidase Inhibitor Kazal type 7 (SPINK7), is a novel tumor suppressor gene from the SPINK family of genes that exhibits anticancer potential. ECRG2 was originally identified during efforts to discover genes involved in esophageal tumorigenesis. ECRG2 was one of those genes whose expression was absent or reduced in primary human esophageal cancers. Additionally, absent or reduced ECRG2 expression was also noted in several other types of human malignancies. ECRG2 missense mutations were identified in various primary human cancers. It was reported that a cancer-derived ECRG2 mutant (valine to glutamic acid at position 30) failed to induce cell death and caspase activation triggered by DNA-damaging anticancer drugs. Furthermore, ECRG2 suppressed cancer cell proliferation in cultured cells and grafted tumors in animals and inhibited cancer cell migration/invasion and metastasis. ECRG2 also was identified as a negative regulator of Hu-antigen R (HuR), an oncogenic RNA-binding protein that is known to regulate mRNA stability and the expression of transcripts corresponding to many cancer-related genes. ECRG2 function is important also for the regulation of inflammatory responses and the maintenance of epithelial barrier integrity in the esophagus. More recently, ECRG2 was discovered as one of the newest members of the pro-apoptotic transcriptional targets of p53. Two p53-binding sites (BS-1 and BS-2) were found within the proximal region of the ECRG2 gene promoter; the treatment of DNA-damaging agents in cancer cells significantly increased p53 binding to the ECRG2 promoter and triggered a strong ECRG2 promoter induction following DNA damage. Further, the genetic depletion of ECRG2 expression significantly impeded apoptotic cell death induced by DNA damage and wild-type p53 in cancer cells. These findings suggest that the loss of ECRG2 expression, commonly observed in human cancers, could play important roles in conferring anticancer drug resistance in human cancers. Thus, ECRG2 is a novel regulator in DNA damage-induced cell death that may also be a potential target for anticancer therapeutics.

Immune cells and their related genes provide a new perspective on the common pathogenesis of ankylosing spondylitis and inflammatory bowel diseases

Background

The close relationship between ankylosing spondylitis (AS) and inflammatory bowel diseases (IBD) has been supported by many aspects, including but not limited to clinical manifestations, epidemiology and pathogenesis. Some evidence suggests that immune cells actively participated in the pathogenesis of both diseases. However, information on which cells are primarily involved in this process and how these cells mobilize, migrate and interact is still limited.

Methods

Datasets were downloaded from Gene Expression Omnibus (GEO) database. Common differentially expressed genes (coDEGs) were identified by package “limma”. The protein-protein interaction (PPI) network and Weighted Gene Co-Expression Network Analysis (WGCNA) were used to analyze the interactions between coDEGs. KEGG pathway enrichment analysis and inverse cumulative distribution function were applied to identify common differential pathways, while Gene Set Enrichment Analysis (GSEA) was used to confirm the significance. Correlation analysis between coDEGs and immune cells led to the identification of critical immune-cell-related coDEGs. The diagnostic models were established based on least absolute shrinkage and selection operator (LASSO) regression, while receiver operating characteristic (ROC) analysis was used to identify the ability of the model. Validation datasets were imported to demonstrate the significant association of coDEGs with specific immune cells and the capabilities of the diagnostic model.

Results

In total, 67 genes were up-regulated and 185 genes were down-regulated in both diseases. Four down-regulated pathways and four up-regulated pathways were considered important. Up-regulated coDEGs were firmly associated with neutrophils, while down-regulated genes were significantly associated with CD8+ T−cells and CD4+ T−cells in both AS and IBD datasets. Five up-regulated and six down-regulated key immue-cell-related coDEGs were identified. Diagnostic models based on key immue-cell-related coDEGs were established and tested. Validation datasets confirmed the significance of the correlation between coDEGs and specific immune cells.

Conclusion

This study provides fresh insights into the co-pathogenesis of AS and IBD. It is proposed that neutrophils and T cells may be actively involved in this process, however, in opposite ways. The immue-cell-related coDEGs, revealed in this study, may be relevant to their regulation, although relevant research is still lacking.

SPINKs in Tumors: Potential Therapeutic Targets

The serine protease inhibitor Kazal type (SPINK) family includes SPINK1-14 and is the largest branch in the serine protease inhibitor family. SPINKs play an important role in pancreatic physiology and disease, sperm maturation and capacitation, Nager syndrome, inflammation and the skin barrier. Evidence shows that the unregulated expression of SPINK1, 2, 4, 5, 6, 7, and 13 is closely related to human tumors. Different SPINKs exhibit various regulatory modes in different tumors and can be used as tumor prognostic markers. This article reviews the role of SPINK1, 2, 4, 5, 6, 7, and 13 in different human cancer processes and helps to identify new cancer treatment targets.