Thrombomodulin gene mutation and associated predisposing factors in familial collapsing glomerulopathy.

INTRODUCTION: Collapsing glomerulopathy (CG) is a rare glomerular disease and its familial form is even rarer. CG and non-collapsing forms of focal segmental glomerulosclerosis (FSGS) may both be caused by pathogenic variants in the same genes, but there is less information on genetics of the former disease. We hypothesized that different hits (viral infection and genetic variants) may be involved in the development of a familial CG here described. METHODS: Renal and etiological routine evaluation, PVB19 serology, genetic tests including whole exome analysis and dosage of serum thrombomodulin (THBD) were performed in two siblings with CG, one healthy sister and their mother. RESULTS: The THBD gene variant p.A43T in homozygosity was identified in the proband and her affected brother, both with CG. The same mutation was identified in their mother in heterozygosity. Thrombomodulin levels were elevated in the serum of both affected siblings. They also had PVB19 positive serology and the G1 high-risk apolipoprotein L1 (APOL1) alelles in homozygosity. Their healthy sister had no PVB19 positive serology and no THBD nor APOL1 gene variants. CONCLUSION: In this case of familial CG, THBD and APOL1 gene variants, and a previous PVB19 infection may be associated with the development of CG in a multi-hit process. In addition, the p.A43T THBD variant, identified in the affected siblings, has never been previously described in homozygosis, pointing to a likely autosomal recessive CG trait caused by this gene mutation.

Autoantibodies against phospholipase A2 receptor in Brazilian patients with glomerular diseases.

BACKGROUND: Recently, great progress has been made in understanding the pathogenesis of membranous nephropathy (MN) with the discovery of autoantibodies (Abs) to M-type phospholipase A2 receptor (PLA2R) in serum and in immunocomplexes deposited in glomerulus in most adult patients with primary MN. OBJECTIVE: To evaluate the diagnostic performance of anti-PLA2R in Brazilian patients with MN, as well as to verify the possible association of anti-PLA2R serum levels with disease activity. METHODS: 117 patients with glomerular diseases confirmed by renal biopsy underwent routinely clinical and laboratory evaluation (serum creatinine and albumin, 24-h proteinuria, urinalysis, tests for etiological investigation) and determination of serum anti-PLA2R by ELISA. RESULTS: 67.5% of the patients had MN, 9.4% focal segmental glomerulosclerosis, 7.7% lupus nephritis class V and 15.4%, other proteinuric glomerular diseases. The mean level of glomerular filtration rate (estimated by the CKD-EPI formula) was 79.43 mL/min (12.00-151.20 mL/min), 24 h proteinuria of 2.89 g (0-14.90 g), serum albumin of 3.79 g/dL (1.20-4.80 g/dL). Anti-PLA2R was detected in 27 patients, all with active MN, being 26 primary and 1 secondary MN. Sensitivity and specificity rates for the test were 60.5-94.7%, and positive (PPV) and negative (NPV) predictive values were 92.9 and 67.9%, respectively. CONCLUSIONS: Anti-PLA2R showed high specificity and PPV for the diagnosis of primary MN in Brazilian patients. There was a strong correlation between disease activity and positive anti-PLA2R. This biomarker represents an important diagnostic tool for primary MN and may contribute to the monitoring of disease activity in such patients.

Cathepsin L in COVID-19: From Pharmacological Evidences to Genetics.

The coronavirus disease 2019 (COVID-19) pandemics is a challenge without precedent for the modern science. Acute Respiratory Discomfort Syndrome (ARDS) is the most common immunopathological event in SARS-CoV-2, SARS-CoV, and MERS-CoV infections. Fast lung deterioration results of cytokine storm determined by a robust immunological response leading to ARDS and multiple organ failure. Here, we show cysteine protease Cathepsin L (CatL) involvement with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and COVID-19 from different points of view. CatL is a lysosomal enzyme that participates in numerous physiological processes, including apoptosis, antigen processing, and extracellular matrix remodeling. CatL is implicated in pathological conditions like invasion and metastasis of tumors, inflammatory status, atherosclerosis, renal disease, diabetes, bone diseases, viral infection, and other diseases. CatL expression is up-regulated during chronic inflammation and is involved in degrading extracellular matrix, an important process for SARS-CoV-2 to enter host cells. In addition, CatL is probably involved in processing SARS-CoV-2 spike protein. As its inhibition is detrimental to SARS-CoV-2 infection and possibly exit from cells during late stages of infection, CatL could have been considered a valuable therapeutic target. Therefore, we describe here some drugs already in the market with potential CatL inhibiting capacity that could be used to treat COVID-19 patients. In addition, we discuss the possible role of host genetics in the etiology and spreading of the disease.

Familial Focal Segmental Glomerulosclerosis With Late-Onset Presentation and R229Q/R291W Podocin Mutations.

INTRODUCTION: Pathogenic variants in different genes have been described as involved in the development of familial focal segmental glomerulosclerosis (FSGS). A more precise genotype-phenotype correlation would be helpful to better characterize the clinical and laboratorial manifestations of this disease, as well as response to treatment. We analyzed podocin (NPHS2) gene variants in 50 members of four generations of a family with late-onset presentation of glomerular disease. RESULTS AND DISCUSSION: The NPHS2 gene variants R229Q and/or R291W were detected in several individuals, and the phenotype of FSGS with progressive loss of renal function was observed in all the family members carrying both mutations simultaneously. Patients manifested ongoing proteinuria over the years and progressive loss of renal function, which in three women culminated in renal replacement therapy by the 4th decade of life. In two affected patients with nephrotic syndrome, remission was not reached by the use of corticosteroids and other immunosuppressive drugs. The R229Q variant was pathogenic only when trans-associated with specific mutations, as the R291W variant in this family. CONCLUSION: Coexistence of the two NPHS2 variants R229Q and R291W in compound heterozygosis was a determinant of the FSGS phenotype. The presence of these variants alone in heterozygosis did not cause significant proteinuria.