Excessive ADAM17 activation occurs in uremic patients and may contribute to their immunocompromised status

Immunomodulatory role of metalloproteinase ADAM17 in tumor development

ADAM17 is a member of the a disintegrin and metalloproteinase (ADAM) family of transmembrane proteases involved in the shedding of some cell membrane proteins and regulating various signaling pathways. More than 90 substrates are regulated by ADAM17, some of which are closely relevant to tumor formation and development. Besides, ADAM17 is also responsible for immune regulation and its substrate-mediated signal transduction. Recently, ADAM17 has been considered as a major target for the treatment of tumors and yet its immunomodulatory roles and mechanisms remain unclear. In this paper, we summarized the recent understanding of structure and several regulatory roles of ADAM17. Importantly, we highlighted the immunomodulatory roles of ADAM17 in tumor development, as well as small molecule inhibitors and monoclonal antibodies targeting ADAM17.

Increased Nectin-4 levels in chronic ketamine abusers and the relationship with lower urinary tract symptoms

Persistent ketamine use causes susceptibility to addiction and bladder toxicity. We examined the association of lower urinary tract symptoms and levels of Nectin-4, a member of the cell adhesion molecules that is essential for maintaining the urothelium barrier in chronic ketamine abusers. We measured the plasma levels of Nectin-4 in 88 patients with ketamine dependence and 69 controls. Patients with ketamine dependence were assessed for ketamine use variables, psychological symptoms, and lower urinary tract symptoms. We found Nectin-4 levels were increased in ketamine-dependent patients compared to the controls (p < 0.0001). Patients with urinary tract symptoms exhibited lower Nectin-4 levels than those without (p = 0.021). Our results suggest an up-regulation of Nectin-4 following chronic and heavy ketamine use. Patients with ketamine dependence with a compromised upregulation of Nectin-4 are likely to have more severe urinary tract symptoms. The mechanisms underlying the involvement of Nectin-4 in ketamine addiction and bladder toxicity warrant future investigation.

Excessive ADAM17 activation occurs in uremic patients and may contribute to their immunocompromised status

Introduction

We previously reported that fibroblast growth factor 23 (FGF23)‐klotho signaling plays a role in B cell immunity. Despite high serum levels of FGF23, a decline in immunity is frequently observed in patients on hemodialysis (HD); thus, abnormalities in the FGF23‐klotho signaling pathway in immune cells may occur in these patients.

Methods

We analyzed the number of klotho‐positive cells in peripheral blood mononuclear cells from 10 male and 6 female patients on HD and 5 healthy male subjects using flow cytometry. We analyzed the abundance of cleaved klotho protein in the murine B cell line, A20, and in the serum of HD patients and healthy subjects (HS) using flow cytometry and Western blotting. The serum level of A disintegrin and metalloprotease 17 (ADAM17) was measured in HD patients and HS using enzyme‐linked immunosorbent assay.

Results

The number of klotho‐positive B cells was reduced in HD patients. Serum ADAM17 was responsible for the reduction in klotho, as a specific ADAM17 inhibitor reversed this change. The total serum levels of ADAM17 were similar in HD patients and HS; however, activated ADAM17 was increased in the serum of HD patients.

Conclusions

We concluded that abnormal ADAM17 activation could contribute to the immunocompromised status in patients on HD, in line with the reported role of ADAM17 as an anti‐inflammatory and immunosuppressive factor.