The Expression Profile of Complement Components in Podocytes

Abstract

Podocytes are critical for maintaining the glomerular filtration barrier and are injured in many renal diseases, especially proteinuric kidney diseases. Recently, reports suggested that podocytes are among the renal cells that synthesize complement components that mediate glomerular diseases. Nevertheless, the profile and extent of complement component expression in podocytes remain unclear. This study examined the expression profile of complement in podocytes under physiological conditions and in abnormal podocytes induced by multiple stimuli. In total, 23/32 complement component components were detected in podocyte by conventional RT-PCR. Both primary cultured podocytes and immortalized podocytes expressed the complement factors C1q, C1r, C2, C3, C7, MASP, CFI, DAF, CD59, C4bp, CD46, Protein S, CR2, C1qR, C3aR, C5aR, and Crry (17/32), whereas C4, CFB, CFD, C5, C6, C8, C9, MBL1, and MBL2 (9/32) complement factors were not expressed. C3, Crry, and C1q-binding protein were detected by tandem mass spectrometry. Podocyte complement gene expression was affected by several factors (puromycin aminonucleoside (PAN), angiotensin II (Ang II), interleukin-6 (IL-6), and transforming growth factor-β (TGF-β)). Representative complement components were detected using fluorescence confocal microscopy. In conclusion, primary podocytes express various complement components at the mRNA and protein levels. The complement gene expressions were affected by several podocyte injury factors.

Podocytes Produce and Secrete Functional Complement C3 and Complement Factor H

“…Staining with Periodic Schiff Acid showed massive sclerosis and glomerular damage ( Figure 7A). In these studies, we confirmed the results of Li et al (35), concerning the glomerular upregulation of C3 mRNA in PAN ( Figure 7B). In addition, we detected an increased induction of CFH in comparison to H 2 O-treated controls (Figure 7C).…”

“…After the detection of C3 production in podocytes, we were interested in investigating the possibility that podocytes secrete other components of the complement cascade. In keeping with the results from Li et al (35), we were also able to detect other components of the complement system in cultured podocytes (Supplementary Figure 1). Nevertheless, we were not able to detect mRNA for the later complement components C6, C7, C8, or C9.…”

“…Sheerin and co-workers demonstrated that local complement production is and that the loss of local complement synthesis in this proteinuria model prevents severe renal damage (34). Based on these findings, a recently published study demonstrates that podocytes, key players in the development of proteinuria, may themselves be one important source of complement C3 in proteinuric diseases (35). Furthermore, Zoshima and colleagues suggested a potential role of podocyte derived CFH in clearing immune complexes in a murine model of immune-complex glomerulonephritis (36).…”

Global Proteomics Deciphered Novel-Function of Osthole Against Pulmonary Arterial Hypertension

“…The association between PAH and SLE suggested that inflammatory process activate a proliferative and inflammatory pulmonary lesions, which eventually lead to vascular remodeling 20 , 27 . Activation of the complement system can directly contribute to vascular leakage, which was observed to be underlying PAH pathogenesis 12 , 28 . Our proteome data illustrated that plasma kallikrein (complement and coagulation cascades Pathway), complement component C9 and ranoclass II (both in systemic lupus erythematosus pathway), CD63 antigen, legumain, Cathepsin S, Cathepsin Z, lysosomal acid lipase(proteins in lysosome pathway) were highly enhanced in PAH, Whereas Histone H3.3, Histone H 3.1(proteins in systemic lupus erythematosus pathway), HMGB1 (base excision repair pathway) were considerably down-regulated in PAH progression, these proteins were markedly recovered by osthole treatment.…”

C3a receptor blockade protects podocytes from injury in diabetic nephropathy

“…Data that showed that increased C3 and C3a staining was also observed in the liver and spleen reflected a systemic complement activation (Supplemental Figure 1; supplemental material available online with this article; https://doi.org/10.1172/ jci.insight.131849DS1). The expression of C3aR, which is known to be present on different renal cells, including podocytes (26)(27)(28)(29), was then evaluated. Immunofluorescence analysis in the renal tissue of control mice revealed weak glomerular C3aR protein expression ( Figure 1C) that increased markedly in BTBR ob/ob mice, specifically in podocytes, as revealed by quantification of costaining of C3aR and nestin ( Figure 1C).…”