Sex and kidney ACE2 expression in primary focal segmental glomerulosclerosis: A NEPTUNE study

Nephrotic Syndrome and Renin-angiotensin System: Pathophysiological Role and Therapeutic Potential

Idiopathic Nephrotic Syndrome (INS) is the most frequent etiology of glomerulopathy in pediatric patients and one of the most common causes of chronic kidney disease (CKD) and end-stage renal disease (ESRD) in this population. In this review, we aimed to summarize evidence on the pathophysiological role and therapeutic potential of the Renin-Angiotensin System (RAS) molecules for the control of proteinuria and for delaying the onset of CKD in patients with INS. This is a narrative review in which the databases PubMed, Web of Science, and Sci- ELO were searched for articles about INS and RAS. We selected articles that evaluated the pathophysiological role of RAS and the effects of the alternative RAS axis as a potential therapy for INS. Several studies using rodent models of nephropathies showed that the treatment with activators of the Angiotensin-Converting Enzyme 2 (ACE2) and with Mas receptor agonists reduces proteinuria and improves kidney tissue damage. Another recent paper showed that the reduction of urinary ACE2 levels in children with INS correlates with proteinuria and higher concentrations of inflammatory cytokines, although data with pediatric patients are still limited. The molecules of the alternative RAS axis comprise a wide spectrum, not yet fully explored, of potential pharmacological targets for kidney diseases. The effects of ACE2 activators and receptor Mas agonists show promising results that can be useful for nephropathies including INS.

Network Pharmacology and In Vivo Experimental Validation to Uncover the Renoprotective Mechanisms of Fangji Huangqi Decoction on Nephrotic Syndrome

Background

Fangji Huangqi decoction (FHD) is a traditional Chinese medicine formula that has the potential efficacy for nephrotic syndrome (NS) treatment. This study aims to explore the effects and underlying mechanisms of FHD against NS via network pharmacology and in vivo experiments.

Methods

The bioactive compounds and targets of FHD were retrieved from the TCMSP database. NS-related targets were collected from GeneCards and DisGeNET databases. The compound-target and protein-protein interaction networks were constructed by Cytoscape 3.8 and BisoGenet, respectively. GO and KEGG analyses were performed by the DAVID online tool. The interactions between active compounds and hub genes were revealed by molecular docking. An NS rat model was established to validate the renoprotective effects and molecular mechanisms of FHD against NS in vivo.

Results

A total of 32 hub genes were predicted to play essential roles in FHD treating NS. Eight main bioactive compounds of FHD had the good affinity with 9 hub targets (CCL2, IL-10, PTGS2, TNF, MAPK1, IL-6, CXCL8, TP53, and VEGFA). The therapeutic effect of FHD on NS was closely involved in the regulation of inflammation and PI3K-Akt pathway. In vivo experiments confirmed the renoprotective effect of FHD on NS, evidenced by reducing the levels of proteinuria, serum creatinine, blood urea nitrogen, and inflammatory factors in NS rats. The PI3K activator 740Y-P weakened the effects of FHD against NS. Furthermore, FHD downregulated the levels of PTGS2, MAPK1, IL-6, and p-Akt in NS rats.

Conclusions

FHD alleviates kidney injury and inflammation in NS by targeting PTGS2, MAPK1, IL-6, and PI3K-Akt pathway.

Follistatin-Like-1 (FSTL1) Is a Fibroblast-Derived Growth Factor That Contributes to Progression of Chronic Kidney Disease

Our understanding of the mechanisms responsible for the progression of chronic kidney disease (CKD) is incomplete. Microarray analysis of kidneys at 4 and 7 weeks of age in Col4a3^-/- mice, a model of progressive nephropathy characterized by proteinuria, interstitial fibrosis, and inflammation, revealed that Follistatin-like-1 (Fstl1) was one of only four genes significantly overexpressed at 4 weeks of age. mRNA levels for the Fstl1 receptors, Tlr4 and Dip2a, increased in both Col4a^-/- mice and mice subjected to unilateral ureteral obstruction (UUO). RNAscope^® (Advanced Cell Diagnostics, Newark CA, USA) localized Fstl1 to interstitial cells, and in silico analysis of single cell transcriptomic data from human kidneys showed Fstl1 confined to interstitial fibroblasts/myofibroblasts. In vitro, FSTL1 activated AP1 and NFκB, increased collagen I (COL1A1) and interleukin-6 (IL6) expression, and induced apoptosis in cultured kidney cells. FSTL1 expression in the NEPTUNE cohort of humans with focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MN), and IgA nephropathy (IgAN) was positively associated with age, eGFR, and proteinuria by multiple linear regression, as well as with interstitial fibrosis and tubular atrophy. Clinical disease progression, defined as dialysis or a 40 percent reduction in eGFR, was greater in patients with high baseline FSTL1 mRNA levels. FSTL1 is a fibroblast-derived cytokine linked to the progression of experimental and clinical CKD.