The functionality of African-specific variants in the TGFB1 regulatory region and their potential role in HIVAN.

BACKGROUND: Transcription of transforming growth factor beta-1 (TGF-ß1) is regulated by a polymorphic promoter region containing African-specific single nucleotide polymorphisms (SNPs). Some of these SNPs have higher frequencies among Southern Africans compared to other African populations and their functionality has only been partially studied. Due to the high prevalence of HIV-associated nephropathy (HIVAN) in Africans we hypothesized that functional African TGFB1-promoter SNPs may contribute to HIVAN pathogenesis. METHODS: The functionality of the TGFB1 -1347 C>T variant and African-specific variants (-1287 G>A, -1154 C>T, -387 C>T and -14 G>A) were examined by measuring reporter gene expression in kidney and fibroblast cell lines co-transfected with TGFB1-promoter constructs and an HIV-Tat expression vector. TGF-ß1 immunohistochemical staining was performed on kidney biopsies with HIVAN (n = 18) and compared to control biopsies without HIVAN or tubulointerstitial disease (n = 12) using semi-quantitative and digital image analysis. HIVAN cases were genotyped for TGFB1 -1347 and -387 SNP variants. RESULTS: TGFB1-promoter haplotypes containing the African -387 T-allele resulted in ~ five-fold repression of TGFB1-promoter activity compared to -387 C haplotypes (p ≤ 0.024). HIV-Tat upregulated TGFB1-promoter activity for haplotypes containing -1347 T and -387 T in transfected renal cells (≈ 1.6-fold; p ≤ 0.030) and fibroblasts (≈ 1.3-fold; p ≤ 0.016). The renal interstitium from HIVAN biopsies, compared to HIV-positive and -negative controls, differed in the semi-quantitative TGF-ß1 staining and digital optical density analyses. The TGFB1 -1347 and -387 genotypes in HIVAN cases were similar to population controls. CONCLUSION: African-specific haplotypes lower TGFB1-promoter activity and expression levels and HIV-Tat upregulates TGFB1 promoter activity irrespective of the haplotype.

Clinico-pathological features of repeat renal biopsies in patients with lupus nephritis at Groote Schuur Hospital, Cape Town.

Background Repeat renal biopsies in patients with lupus nephritis are usually done to guide treatment or to establish disease chronicity. Their value is not clear from available literature. There are also no available data in Africa to guide clinicians. Methods This was a retrospective study of patients undergoing a repeat renal biopsy between January 2003 and December 2014 from a single centre in Cape Town, South Africa. Relevant demographic, clinical and histological records of patients with repeat renal biopsies were documented. Comparison of data from first and second renal biopsy was performed. Results Forty-four patients had at least two biopsies done during the study period. Most patients were females (81.8%). The mean biopsy interval was 2.8 ± 1.8 (range 0.38-9.4) years. Proteinuria was the main indication for the repeat biopsy (36.1%). The glomerular filtration rate and proteinuria worsened between the two biopsies ( p = 0.001 and 0.019, respectively) suggesting disease progression. Most patients (65.4%) with a non-proliferative class of lupus nephritis at first biopsy progressed into a proliferative class, whereas patients with initial proliferative lupus nephritis at first biopsy (77.8%) remained as proliferative at repeat biopsy. Treatment was changed in 85% of patients at second biopsy. Conclusion Repeat renal biopsies in patients with lupus nephritis presents a useful means of assessing disease progression and provides guidance regarding modification of treatment. More studies are, however, required to evaluate the value of repeat biopsies and perhaps the need for protocol renal biopsies in patients with lupus nephritis.

Investigating the threshold for early renal allograft biopsy: A South African single-centre perspective.

BACKGROUND: The most common clinical indication for renal biopsy in the early post-transplant period is early graft dysfunction (EGD), which may present either as delayed graft function (DGF) or acute graft dysfunction. Even though it is a valuable diagnostic tool, renal allograft biopsy is not without risk of major complications. Recent studies have suggested that, with modern immunosuppressive induction regimens and more accurate ways to determine high immunological risk transplants, early acute rejection (AR) is uncommon and routine biopsy for EGD does not result in a change in management. OBJECTIVES: To describe the histological findings and complications of renal allograft biopsies for EGD in our setting, and to determine whether our current threshold for biopsy is appropriate. METHODS: This study was a retrospective audit that included all patients who underwent renal allograft biopsy within the first 30 days of transplantation at Groote Schuur Hospital, Cape Town, South Africa, from 1 June 2010 to 30 June 2018. The indication for biopsy was any patient who showed significant EGD, characterised by acute graft dysfunction or DGF with dialysis dependence. RESULTS: During the study period, 330 patients underwent renal transplantation, of whom 105 (32%) had an early biopsy and were included in the study. The median age of recipients was 39 (range 17 - 62) years, with 65% males and 35% females. The majority of donors were deceased donations after brain death (70%), with an overall median cold ischaemic time of 9 hours (interquartile range (IQR) 4 - 16). The average number of human leukocyte antigen mismatches was 5 (IQR 4 - 7). A donor-specific antibody was recorded for 18% of recipients and a panel-reactive antibody score of >30% was recorded for 21%. The median duration after transplant for biopsy was 8 (IQR 6 - 10) days. During the first month of EGD, AR was diagnosed in 42% of patients who underwent biopsies. In 21% of these patients, there was acute cellular rejection, in 16% antibody-mediated rejection, and in 5% both of these. Acute tubular necrosis was the primary finding in 32%, with acute interstitial nephritis in 8%, and acute calcineurin toxicity in 4% of cases. A significant biopsy-related complication was recorded in 3 patients: 1 small-bowel perforation repaired via laparotomy, and 2 vascular injuries successfully embolised by interventional radiology. CONCLUSIONS: Considering the relative safety and high rate of detection of AR, a liberal approach to renal biopsy for EGD remains justifiable in our setting.