Contribution of functional and quantitative genetic variants of Complement Factor H and Factor H-Related (FHR) proteins on renal pathology

Immune and regulative characterization of complement-related gene cfhl5 in response to Vibrio harveyi challenge in Cynoglossus semilaevis

Complement factor H-related protein (CFHR) plays an important role in regulating complement activation and defensive responses. The function of CFHR2 (complement factor H related 2), a member of the CFHR family, in fish remains unclear. Here, we report the genetic relationship, expression characteristics and regulatory mechanism of cfhl5 (complement factor H like 5) gene, which encodes CFHR2 in Chinese tongue sole. We observed that the cfhl5 gene was widely expressed in several tissues, such as brain, heart and immune organs, and was most abundantly expressed in liver. After injection with Vibrio harveyi, the expression of cfhl5 was up-regulated significantly in liver, spleen and kidney at 12 or 24 hours post infection (hpi), suggesting an involvement of this gene in the acute immune response. Knockdown of cfhl5 in liver cells significantly up-regulated the expression of the pro-inflammatory cytokines tnf-α (tumor necrosis factor-alpha) and il1β (interleukin-1beta), the immunomodulatory factor il10 (interleukin-10) and the lectin complement pathway gene masp1 (MBL-associated serine protease 1), and down-regulated the expression of complement components c3 (complement 3) and cfi (complement factor I). In our previous work, we found that cfhl5 gene was significantly higher methylated and lower expressed in the resistant family compared with the susceptible family. Therefore, we used dual-luciferase reporter system to determine the effect of DNA methylation on this gene and found that DNA methylation could inhibit the promoter activity to reduce its expression. These results demonstrated that the expression of cfhl5 is regulated by DNA methylation, and this gene might play an important role in the immune response by regulating the expression of cytokines and complement components genes in Chinese tongue sole.

C3 Glomerulonephritis Presenting With Nephritic and Nephrotic Syndromes: Spontaneous Remission After Six Months on Dialysis

C3 glomerulopathy is a rare and complex renal disease driven by complement dysregulation, with variable presentation and pathophysiology. We report the case of a middle-aged male patient presenting with nephritic and nephrotic syndromes and low serum C3, whose biopsy established the diagnosis of C3 glomerulonephritis. He was found to be homozygous for the complement factor H-related protein (CFHR)3-CFHR1 deletion, which has been associated with the development of anti-factor H autoantibodies. However, the lack of consistent and accessible nephritic factor assays prevented full clarification of the mechanisms involved in the disease. Interestingly, despite not receiving treatment due to suspicion of malignancy and perceived poor renal prognosis, there was spontaneous recovery after six months on hemodialysis. This case reflects the enduring challenges in establishing the diagnosis and prognosis of C3 glomerulonephritis.