Geographic variation of mutagenic exposures in kidney cancer genomes

International differences in the incidence of many cancer types indicate the existence of carcinogen exposures that have not yet been identified by conventional epidemiology make a substantial contribution to cancer burden1. In clear cell renal cell carcinoma, obesity, hypertension and tobacco smoking are risk factors, but they do not explain the geographical variation in its incidence2. Underlying causes can be inferred by sequencing the genomes of cancers from populations with different incidence rates and detecting differences in patterns of somatic mutations. Here we sequenced 962 clear cell renal cell carcinomas from 11 countries with varying incidence. The somatic mutation profiles differed between countries. In Romania, Serbia and Thailand, mutational signatures characteristic of aristolochic acid compounds were present in most cases, but these were rare elsewhere. In Japan, a mutational signature of unknown cause was found in more than 70% of cases but in less than 2% elsewhere. A further mutational signature of unknown cause was ubiquitous but exhibited higher mutation loads in countries with higher incidence rates of kidney cancer. Known signatures of tobacco smoking correlated with tobacco consumption, but no signature was associated with obesity or hypertension, suggesting that non-mutagenic mechanisms of action underlie these risk factors. The results of this study indicate the existence of multiple, geographically variable, mutagenic exposures that potentially affect tens of millions of people and illustrate the opportunities for new insights into cancer causation through large-scale global cancer genomics.

DCLRE1B/Apollo germline mutations associated with renal cell carcinoma impair telomere protection

Hereditary renal cell carcinoma (RCC) is caused by germline mutations in a subset of genes, including VHL, MET, FLCN, and FH. However, many familial RCC cases do not harbor mutations in the known predisposition genes. Using Whole Exome Sequencing, we identified two germline missense variants in the DCLRE1B/Apollo gene (ApolloN246I and ApolloY273H) in two unrelated families with several RCC cases. Apollo encodes an exonuclease involved in DNA Damage Response and Repair (DDRR) and telomere integrity. We characterized these two functions in the human renal epithelial cell line HKC8. The decrease or inhibition of Apollo expression sensitizes these cells to DNA interstrand crosslink damage (ICLs). HKC8 Apollo-/- cells appear defective in the DDRR and present an accumulation of telomere damage. Wild-type and mutated Apollo forms could interact with TRF2, a shelterin protein involved in telomere protection. However, only ApolloWT can rescue the telomere damage in HKC8 Apollo-/- cells. Our results strongly suggest that ApolloN246I and ApolloY273H are loss-of-function mutants that cause impaired telomere integrity and could lead to genomic instability. Altogether, our results suggest that mutations in Apollo could induce renal oncogenesis.

Immune checkpoints are predominantly co-expressed by clonally expanded CD4+FoxP3+ intratumoral T-cells in primary human cancers

BACKGROUND

In addition to anti-PD(L)1, anti-CTLA-4 and anti-LAG-3, novel immune checkpoint proteins (ICP)-targeted antibodies have recently failed to demonstrate significant efficacy in clinical trials. In these trials, patients were enrolled without screening for drug target expression. Although these novel ICP-targeted antibodies were expected to stimulate anti-tumor CD8 + T-cells, the rationale for their target expression in human tumors relied on pre-clinical IHC stainings and transcriptomic data, which are poorly sensitive and specific techniques for assessing membrane protein expression on immune cell subsets. Our aim was to describe ICP expression on intratumoral T-cells from primary solid tumors to better design upcoming neoadjuvant cancer immunotherapy trials.

METHODS

We prospectively performed multiparameter flow cytometry and single-cell RNA sequencing (scRNA-Seq) paired with TCR sequencing on freshly resected human primary tumors of various histological types to precisely determine ICP expression levels within T-cell subsets.

RESULTS

Within a given tumor type, we found high inter-individual variability for tumor infiltrating CD45 + cells and for T-cells subsets. The proportions of CD8+ T-cells (~ 40%), CD4+ FoxP3- T-cells (~ 40%) and CD4+ FoxP3+ T-cells (~ 10%) were consistent across patients and indications. Intriguingly, both stimulatory (CD25, CD28, 4-1BB, ICOS, OX40) and inhibitory (PD-1, CTLA-4, PD-L1, CD39 and TIGIT) checkpoint proteins were predominantly co-expressed by intratumoral CD4+FoxP3+ T-cells. ScRNA-Seq paired with TCR sequencing revealed that T-cells with high clonality and high ICP expressions comprised over 80% of FoxP3+ cells among CD4+ T-cells. Unsupervised clustering of flow cytometry and scRNAseq data identified subsets of CD8+ T-cells and of CD4+ FoxP3- T-cells expressing certain checkpoints, though these expressions were generally lower than in CD4+ FoxP3+ T-cell subsets, both in terms of proportions among total T-cells and ICP expression levels.

CONCLUSIONS

Tumor histology alone does not reveal the complete picture of the tumor immune contexture. In clinical trials, assumptions regarding target expression should rely on more sensitive and specific techniques than conventional IHC or transcriptomics. Flow cytometry and scRNAseq accurately characterize ICP expression within immune cell subsets. Much like in hematology, flow cytometry can better describe the immune contexture of solid tumors, offering the opportunity to guide patient treatment according to drug target expression rather than tumor histological type.

Prognostic value of programmed death ligand-1 and programmed death-1 expression in patients with upper tract urothelial carcinoma

OBJECTIVE

To evaluate the prognostic value of programmed death ligand-1 (PD-L1) and programmed death-1 (PD-1) expression in patients with upper tract urothelial carcinoma (UTUC).

PATIENTS AND METHODS

A retrospective multicentre study was conducted in 283 patients with UTUC treated with radical nephroureterectomy (RNU) between 2000 and 2015 at 10 French hospitals. Immunohistochemistry analyses were performed using 2 mm-core tissue microarrays with NAT105® and 28.8® antibodies at a 5% cut-off for positivity on tumour cells and tumour-infiltrating lymphocytes to evaluate PD-L1 and PD-1 expression, respectively. Multivariable Cox regression models were used to determine the independent predictors of recurrence-free (RFS), cancer-specific (CSS) and overall survival (OS).

RESULTS

Overall, 63 (22.3%) and 220 (77.7%) patients with UTUC had PD-L1-positive and -negative disease, respectively, while 91 (32.2%) and 192 (67.8%) had PD-1-positive and -negative disease, respectively. Patients who expressed PD-L1 or PD-1 were more likely to have pathological tumour stage ≥pT2 (68.3% vs 49.5%, P = 0.009; and 69.2% vs 46.4%, P < 0.001, respectively) and high-grade (90.5% vs 70.0%, P = 0.001; and 91.2% vs 66.7%, P < 0.001, respectively) disease with lymphovascular invasion (52.4% vs 17.3%, P < 0.001; and 39.6% vs 18.2%, P < 0.001, respectively) as compared to those who did not. In multivariable Cox regression analysis adjusting for each other, PD-L1 and PD-1 expression were significantly associated with decreased RFS (hazard ratio [HR] 1.83, 95% confidence interval [CI] 1.09-3.08, P = 0.023; and HR 1.59, 95% CI 1.01-2.54, P = 0.049; respectively), CSS (HR 2.73, 95% CI 1.48-5.04, P = 0.001; and HR 1.96, 95% CI 1.12-3.45, P = 0.019; respectively) and OS (HR 2.08, 95% CI 1.23-3.53, P = 0.006; and HR 1.71, 95% CI 1.05-2.78, P = 0.031; respectively). In addition, multivariable Cox regression analyses evaluating the four-tier combination of PD-L1 and PD-1 expression showed that only PD-L1/PD-1-positive patients (n = 38 [13.4%]) had significantly decreased RFS (HR 3.07, 95% CI 1.70-5.52; P < 0.001), CSS (HR 5.23, 95% CI 2.62-10.43; P < 0.001) and OS (HR 3.82, 95% CI 2.13-6.85; P < 0.001) as compared to those with PD-L1/PD-1-negative disease (n = 167 [59.0%]).

CONCLUSIONS

We observed that PD-L1 and PD-1 expression were both associated with adverse pathological features that translated into an independent and cumulative adverse prognostic value in UTUC patients treated with RNU.

C3 Glomerulopathy With Concurrent Thrombotic Microangiopathy: Clinical and Immunological Features

RATIONALE & OBJECTIVE

C3 glomerulopathy (C3GN) and atypical hemolytic uremic syndrome (aHUS) are 2 distinct rare kidney diseases caused by dysregulation of the alternative complement pathway. Patients with C3GN and concurrent kidney lesions of thrombotic microangiopathy (TMA) have been rarely reported. We characterized the clinical features and underlying immunological abnormalities in these patients.

STUDY DESIGN

Case series.

SETTING & PARTICIPANTS

Patients with C3GN and concomitant TMA lesions on biopsy registered from 2009 to 2019 in the French National Registry of C3GN.

FINDINGS

Among 278 registered patients with C3GN, 16 (6%) had biopsy-proven glomerular and/or vascular TMA lesions. Their median age at diagnosis was 39 years (range, 7-76), and 59% were female. Fourteen of the 16 patients (88%) had an estimated glomerular filtration rate of<30mL/min/1.73m2 and 3 of 16 (19%) required dialysis. Twelve of the 14 evaluated patients (86%) showed evidence of mechanical hemolysis. Fifty percent of the patients had low C3 levels. Six of the 14 evaluated patients had a rare variant in complement genes, and 4 of the 16 patients (25%) had monoclonal gammopathy. Among the 16 patients, 10 (63%) received eculizumab, 5 (31%) received immunosuppressive therapy, and 4 (25%) received clone-targeted chemotherapy. Median kidney survival was 49 months.

LIMITATIONS

Small retrospective case series with a limited number of biopsies including electron microscopy.

CONCLUSIONS

Concomitant C3GN and TMA is extremely rare and is associated with poor kidney outcomes. Genetic or acquired abnormalities of the alternative complement pathway are common as is the presence of monoclonal gammopathy, which may inform the selection of treatment approaches.

Pathological spectrum of hereditary transthyretin renal amyloidosis and clinicopathologic correlation: a French observational study

BACKGROUND

Cardiac and neurological involvements are the main clinical features of hereditary transthyretin (ATTRv) amyloidosis. Few data are available about ATTRv amyloid nephropathy (ATTRvN).

METHODS

We retrospectively included 30 patients with biopsy-proven ATTRvN [V30M (26/30) including two domino liver recipients, S77Y (2/30), V122I (1/30) and S50R (1/30) variants] from two French reference centers. We described the pathological features by comparing amyloid deposits distribution to patients with AL or AA amyloidosis, and sought to determine clinicopathological correlation with known disease-modifying factors such as TTR variant, gender and age at diagnosis.

RESULTS

In comparison with AL and AA amyloidosis, ATTRv patients had similar glomerular, arteriolar and arterial amyloid deposits, but more cortical and medullary tubulointerstitial (33%, 44%, 77%, P = .03) involvement. While the presence of glomerular deposits is associated with the range of proteinuria, some patients with abundant glomerular ATTRv amyloidosis had no significant proteinuria. V30M patients had more glomerular (100% and 25%, odds ratio = 114, 95% confidence interval 3.85-3395.00, P = .001) deposits, and higher estimated glomerular filtration rate [50 (interquartile range 44-82) and 27 (interquartile range 6-31) mL/min/1.73 m², P = .004] than non-V30M patients. We did not find difference in amyloid deposition according to gender or age at diagnosis.

CONCLUSION

ATTRvN affects all kidney compartments, but compared with AL/AA amyloidosis, ATTRvN seems to involve more frequently tubulointerstitial areas. V30M patients represents the dominant face of the disease with a higher risk of glomerular/arteriolar involvement. ATTRvN should thus be considered in patients, and potential relatives, with ATTRv amyloidosis and kidney dysfunction, regardless of proteinuria level.

Clinical and Prognostic Factors in Patients with IgG4-Related Kidney Disease

BACKGROUND

IgG4-related kidney disease is a major manifestation of IgG4-related disease, a systemic fibroinflammatory disorder. However, the clinical and prognostic kidney-related factors in patients with IgG4-related kidney disease are insufficiently defined.

METHODS

We conducted an observational cohort study using data from 35 sites in two European countries. Clinical, biologic, imaging, and histopathologic data; treatment modalities; and outcomes were collected from medical records. Logistic regression was performed to identify the possible factors related to an eGFR ≤30 ml/min per 1.73 m 2 at the last follow-up. Cox proportional hazards model was performed to assess the factors associated with the risk of relapse.

RESULTS

We studied 101 adult patients with IgG4-related disease with a median follow-up of 24 (11-58) months. Of these, 87 (86%) patients were male, and the median age was 68 (57-76) years. Eighty-three (82%) patients had IgG4-related kidney disease confirmed by kidney biopsy, with all biopsies showing tubulointerstitial involvement and 16 showing glomerular lesions. Ninety (89%) patients were treated with corticosteroids, and 18 (18%) patients received rituximab as first-line therapy. At the last follow-up, the eGFR was below 30 ml/min per 1.73 m 2 in 32% of patients; 34 (34%) patients experienced a relapse, while 12 (13%) patients had died. By Cox survival analysis, the number of organs involved (hazard ratio [HR], 1.26; 95% confidence interval [CI], 1.01 to 1.55) and low C3 and C4 concentrations (HR, 2.31; 95% CI, 1.10 to 4.85) were independently associated with a higher risk of relapse, whereas first-line therapy with rituximab was protective (HR, 0.22; 95% CI, 0.06 to 0.78). At their last follow-up, 19 (19%) patients had an eGFR ≤30 ml/min per 1.73 m 2 . Age (odd ratio [OR], 1.11; 95% CI, 1.03 to 1.20), peak serum creatinine (OR, 2.74; 95% CI, 1.71 to 5.47), and serum IgG4 level ≥5 g/L (OR, 4.46; 95% CI, 1.23 to 19.40) were independently predictive for severe CKD.

CONCLUSIONS

IgG4-related kidney disease predominantly affected middle-aged men and manifested as tubulointerstitial nephritis with potential glomerular involvement. Complement consumption and the number of organs involved were associated with a higher relapse rate, whereas first-line therapy with rituximab was associated with lower relapse rate. Patients with high serum IgG4 concentrations (≥5 g/L) had more severe kidney disease.

Photodynamic cystoscopy for bladder cancer diagnosis and for NMIBC follow-up: An overview of systematic reviews and meta-analyses

INTRODUCTION

Currently, bladder cancer detection is based on cytology and cystoscopy. White light cystoscopy (WLC) is an invasive procedure and may under-detect flat lesions. Blue light cystoscopy (BLC) and narrow band imaging (NBI) cystoscopy are new modalities that could improve the detection of non-muscle invasive bladder cancer (NMIBC) and its recurrence or progression to muscle invasive bladder cancer. We present a systematic review on BLC and NBI cystoscopy for bladder cancer diagnosis and NMIBC follow-up.

MATERIAL AND METHODS

All available systematic reviews and meta-analyses on cystoscopy published in PubMed® between May 2010 and March 2021 were identified and reviewed. The main endpoints were clinical performance for bladder cancer diagnosis and for recurrence or progression detection during NMIBC follow-up, and additional value compared with cytology and/or WLC.

RESULTS

Most of the meta-analyses and systematic reviews published suggest a better sensitivity of BLC and NBI cystoscopy compared to WLC, particularly for the detection of flat lesions (CIS). NBI- and BLC-guided TURBT could decrease the recurrence rates. However, their clinical utility to reduce progression rate and increase survival is still unclear.

CONCLUSIONS

BLC and NBI cystoscopy are efficient techniques for bladder cancer diagnosis and NMIBC follow-up. However, their clinical benefit remains to be confirmed.

Urinary biomarkers for bladder cancer diagnosis and NMIBC follow-up: a systematic review

BACKGROUND

Bladder cancer detection and follow-up is based on cystoscopy and/or cytology, but it remains imperfect and invasive. Current research focuses on diagnostic biomarkers that could improve bladder cancer detection and follow-up by discriminating patients at risk of aggressive cancer who need confirmatory TURBT (Transurethral Resection of Bladder Tumour) from patients at no risk of aggressive cancer who could be spared from useless explorations.

OBJECTIVE

To perform a systematic review of data on the clinical validity and clinical utility of eleven urinary biomarkers (VisioCyt^®, Xpert^®Bladder, BTA stat^®, BTA TRAK™, NMP22 BC^®, NMP22^® BladderChek^® Test, ImmunoCyt™/uCyt1+™, UroVysion Bladder Cancer Kit^®, Cxbladder, ADXBLADDER, Urodiag^®) for bladder cancer diagnosis and for non-muscle invasive bladder cancer (NMIBC) follow-up.

METHODS

All available studies on the 11 biomarkers published between May 2010 and March 2021 and present in MEDLINE^® were reviewed. The main endpoints were clinical performance for bladder cancer detection, recurrence or progression during NMIBC monitoring, and additional value compared to cytology and/or cystoscopy.

RESULTS

Most studies on urinary biomarkers had a prospective design and high level of evidence. However, their results should be interpreted with caution given the heterogeneity among studies. Most of the biomarkers under study displayed higher detection sensitivity compared with cytology, but lower specificity. Some biomarkers may have clinical utility for NMIBC surveillance in patients with negative or equivocal cystoscopy or negative or atypical urinary cytology findings, and also for recurrence prediction.

CONCLUSION

Urinary biomarkers might have a complementary place in bladder cancer diagnosis and NMIBC surveillance. However, their clinical benefit remains to be confirmed.

Testicular Lesions in Infertile Men

OBJECTIVES

An increasing number of incidental testicular tumors are diagnosed in patients during infertility workup. The aim of this study was to evaluate the accuracy of frozen section examination (FSE) for the management of these tumors.

METHODS

We retrospectively studied a series of 46 testicular tumors diagnosed during exploration for infertility from 2000 to 2019 and submitted for FSE.

RESULTS

A diagnosis of malignancy was made in 23 cases on both gross examination (yellow-white or cream-colored nodules for seminomas) and FSE, then confirmed on final diagnosis in 22 of the cases. One seminoma reported on FSE was revised as being a Leydig cell tumor. The 23 other lesions were diagnosed as benign on FSE, including 11 Leydig cell tumors (yellow-brown nodules), 2 Leydig cell hyperplasias, and 10 whitish fibrous lesions. All Leydig cell lesions were confirmed except 1, which was reclassified as a Sertoli cell tumor. Of the 10 cases of fibrous lesions, 6 were associated with malignancy.

CONCLUSIONS

The high incidence of Leydig cell tumors and the accuracy of FSE for these lesions demonstrate the interest in FSE. In contrast, FSE is not reliable for fibrous lesions, and surgeons should be aware that a fibrosis result often corresponds with regressed tumors.

Clear cell and papillary renal cell carcinomas in hereditary papillary renal cell carcinoma (HPRCC) syndrome: a case report

Background

Hereditary papillary renal cell carcinoma (HPRCC) is a rare autosomal dominant disease characterized by the development of multiple and bilateral papillary type I renal cell carcinomas (RCC) and papillary adenomas caused by activating mutations in the MET proto-oncogene. Classically, distinctive histological features of RCC are described according to the familial renal cell carcinoma syndrome. To date, no clear cell RCC has been reported in HPRCC syndrome.

Case presentation

We describe the case of a 51-year-old man with a germline MET mutation detected on peripheral blood testing, and no germline VHL mutation, who developed numerous papillary tumors but also unexpectedly clear cell renal cell carcinomas. During the follow-up, an adrenal metastasis was observed 7 years after the initial diagnosis corresponding to a clear cell RCC metastasis. By immunohistochemistry, clear cell tumors showed focal cytokeratin 7, moderate racemase, and diffuse and membranous CAIX expression, while papillary tumors expressed strong diffuse cytokeratin 7 and racemase without CAIX positivity. Using FISH, VHL deletion was observed in one of the clear cell tumors, and the metastatic clear cell tumor presented a trisomy of chromosomes 7 and 17. These last genomic alterations are usually detected in papillary RCC, highlighting the potential link between both histological subtypes of tumors and the HPRCC syndrome.

Conclusions

The pathologist must be aware that the presence of a non-papillary RCC associated with numerous papillary tumors should not exclude the diagnostic suspicion of HPRCC and thus to perform a thorough genomic study.

Azoospermia and reciprocal translocations: should whole-exome sequencing be recommended?

Background

Although chromosome rearrangements are responsible for spermatogenesis failure, their impact depends greatly on the chromosomes involved. At present, karyotyping and Y chromosome microdeletion screening are the first-line genetic tests for patients with non-obstructive azoospermia. Although it is generally acknowledged that X or Y chromosome rearrangements lead to meiotic arrest and thus rule out any chance of sperm retrieval after a testicular biopsy, we currently lack markers for the likelihood of testicular sperm extraction (TESE) in patients with other chromosome rearrangements.

Results

We investigated the use of a single nucleotide polymorphism comparative genome hybridization array (SNP-CGH) and whole-exome sequencing (WES) for two patients with non-obstructive azoospermia and testicular meiotic arrest, a reciprocal translocation: t(X;21) and t(20;22), and an unsuccessful TESE. No additional gene defects were identified for the t(X;21) carrier - suggesting that t(X;21) alone damages spermatogenesis. In contrast, the highly consanguineous t(20;22) carrier had two deleterious homozygous variants in the TMPRSS9 gene; these might have contributed to testicular meiotic arrest. Genetic defect was confirmed with Sanger sequencing and immunohistochemical assessments on testicular tissue sections.

Conclusions

Firstly, TMPRSS9 gene defects might impact spermatogenesis. Secondly, as a function of the chromosome breakpoints for azoospermic patients with chromosome rearrangements, provision of the best possible genetic counselling means that genetic testing should not be limited to karyotyping. Given the risks associated with TESE, it is essential to perform WES - especially for consanguineous patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12610-021-00145-5.

Involvement of PBRM1 in VHL disease-associated clear cell renal cell carcinoma and its putative relationship with the HIF pathway

Von Hippel-Lindau (VHL) disease is the main cause of inherited clear-cell renal cell carcinoma (ccRCC) and is caused by germline mutations in the VHL tumor suppressor gene. Bi-allelic VHL alterations lead to inactivation of pVHL, which plays a major role by downstream activation of the hypoxia inducible factor (HIF) pathway. Somatic VHL mutations occur in 80% of sporadic ccRCC cases and the second most frequently mutated gene is polybromo 1 (PBRM1). As there is currently no data regarding PBRM1 involvement in VHL disease-associated ccRCC, the aim of the present study was to assess the PBRM1 mutational status, and PBRM1 and HIF expression in VHL disease-associated ccRCC series compared with a sporadic series. PBRM1 gene was screened by Sanger sequencing for 23 VHL-disease-associated ccRCC and 22 sporadic ccRCC cases. Immunohistochemical studies were performed to detect the expression of PBRM1, HIF1 and HIF2 for all cases. In VHL-associated tumors, 13.0% (n=3/23) had PBRM1 somatic mutations and 17.4% (n=4/23) had a loss of PBRM1 nuclear expression. In sporadic cases, 27.3% (n=6/22) showed PBRM1 somatic mutations and 45.5% (n=10/22) had a loss of PBRM1 nuclear expression. Loss of PBRM1 was associated with an advanced tumor stage. HIF1-positive tumors were observed more frequently in the VHL-associated ccRCC than in the sporadic series. Furthermore, in the VHL cohort, PBRM1 expression appeared to be associated more with HIF1 than with HIF2. Given that hereditary tumors tend to be less aggressive, these results would suggest that co-expression of PBRM1 and HIF1 may have a less oncogenic role in VHL-associated ccRCC.

IL-15 Prevents Renal Fibrosis by Inhibiting Collagen Synthesis: A New Pathway in Chronic Kidney Disease?

Chronic kidney disease (CKD), secondary to renal fibrogenesis, is a public health burden. The activation of interstitial myofibroblasts and excessive production of extracellular matrix (ECM) proteins are major events leading to end-stage kidney disease. Recently, interleukin-15 (IL-15) has been implicated in fibrosis protection in several organs, with little evidence in the kidney. Since endogenous IL-15 expression decreased in nephrectomized human allografts evolving toward fibrosis and kidneys in the unilateral ureteral obstruction (UUO) model, we explored IL-15's renoprotective role by pharmologically delivering IL-15 coupled or not with its soluble receptor IL-15Rα. Despite the lack of effects on myofibroblast accumulation, both IL-15 treatments prevented tubulointerstitial fibrosis (TIF) in UUO as characterized by reduced collagen and fibronectin deposition. Moreover, IL-15 treatments inhibited collagen and fibronectin secretion by transforming growth factor-β (TGF-β)-treated primary myofibroblast cultures, demonstrating that the antifibrotic effect of IL-15 in UUO acts, in part, through a direct inhibition of ECM synthesis by myofibroblasts. In addition, IL-15 treatments resulted in decreased expression of monocyte chemoattractant protein 1 (MCP-1) and subsequent macrophage infiltration in UUO. Taken together, our study highlights a major role of IL-15 on myofibroblasts and macrophages, two main effector cells in renal fibrosis, demonstrating that IL-15 may represent a new therapeutic option for CKD.

Germline mutation in the NBR1 gene involved in autophagy detected in a family with renal tumors

Hereditary Renal Cell Carcinomas (RCC) are caused by mutations in predisposing genes, the major ones including VHL, FLCN, FH and MET. However, many families with inherited RCC have no germline mutation in these genes. Using Whole Exome Sequencing on germline DNA from a family presenting three different histological renal tumors (an angiomyolipoma, a clear-cell RCC and an oncocytic papillary RCC), we identified a frameshift mutation in the Neighbor of BRCA1 gene 1 (NBR1), segregating with the tumors. NBR1 encodes a cargo receptor protein involved in autophagy. Genetic and functional analyses suggested a pathogenic impact of the mutation. Indeed, functional study performed in renal cell lines showed that the mutation alters NBR1 interactions with some of its partners (such as p62/SQSTM1), leading to a dominant negative effect. This results in an altered autophagic process and an increased proliferative capacity in renal cell lines. Our study suggests that NBR1 may be a new predisposing gene for RCC, however its characterization needs to be further investigated in order to confirm its role in renal carcinogenesis.

The Clinicopathological Spectrum of Kidney Lesions in Chikungunya Fever: A Report of 5 Cases With Kidney Biopsy

Chikungunya nephropathy is an uncommon etiology of acute kidney injury, associated with the mosquito-borne chikungunya arbovirus (CHIKV). The very limited number of pathologic reports to date have only involved postmortem analyses. We here report 5 cases of acute kidney injury for which kidney biopsies were performed in patients with confirmed acute CHIKV infection, during the recent outbreak of chikungunya disease in the French West Indies. The patients ranged from 42 to 76 years of age. All of the patients developed kidney injury, 3 of whom required short-term dialysis and underwent a kidney biopsy. Analysis of kidney biopsies revealed 2 main histopathologic patterns: acute interstitial nephritis with predominant lymphoid inflammation and acute tubular injury. Epithelioid granulomas were observed in 2 cases. There were no glomerular lesions, except in biopsies from 2 patients, including 1 with a previous known primary focal segmental glomerulosclerosis. CHIKV antigen immunofluorescence microscopy revealed staining in tubular cells. In all of the cases, the short-term outcome was favorable, with recovery of kidney function.

Long-term exposure to monoclonal anti-TNF is associated with an increased risk of lymphoma in BAFF-transgenic mice

The impact of treatment on the risk of lymphoma in patients with rheumatoid arthritis (RA) is unclear. Here, we aimed to assess if the risk of lymphoma differs according to the type of tumor necrosis factor inhibitor (TNFi), comparing monoclonal anti-TNF antibodies to the soluble TNF receptor. We used B cell activating factor belonging to the TNF family (BAFF)-transgenic (Tg) mice as a model of autoimmunity-associated lymphoma. Six-month-old BAFF-Tg mice were treated with TNFi for 12 months. Histological examination of the spleen, assessment of the cellular composition of the spleen by flow cytometry and assessment of B cell clonality were performed at euthanasia. Crude mortality and incidence of lymphoma were significantly higher in mice treated with monoclonal anti-TNF antibodies compared to both controls and mice treated with the soluble TNF receptor, even at a high dose. Flow cytometry analysis revealed decreased splenic macrophage infiltration in mice treated with monoclonal anti-TNF antibodies. Overall, this study demonstrates, for the first time, that a very prolonged treatment with monoclonal anti-TNF antibodies increase the risk of lymphoma in B cell-driven autoimmunity. These data suggest a closer monitoring for lymphoma development in patients suffering from B cell-driven autoimmune disease with long-term exposure to monoclonal anti-TNF antibodies.

The spectrum of kidney biopsies in hospitalized patients with COVID-19, acute kidney injury, and/or proteinuria

We report a multicentric retrospective case series of patients with COVID-19 who developed acute kidney injury and/or proteinuria and underwent a kidney biopsy in the Paris and its metropolitan area. Forty-seven patients (80.9% men) with COVID-19 who underwent a kidney biopsy between March 08 and May 19, 2020 were included. Median age was 63 years IQR [52-69]. Comorbidities included hypertension (66.0%), diabetes mellitus (27.7%), obesity (27.7%), history of chronic kidney (25.5%), cardiac (38.6%) and respiratory (27.3%) diseases. Initial symptoms were fever (85.1%), cough (63.8%), shortness of breath (55.3%), and diarrhea (23.4%). Almost all patients developed acute kidney injury (97.9%) and 63.8% required renal replacement therapy. Kidney biopsy showed two main histopathological patterns, including acute tubular injury in 20 (42.6%) patients, and glomerular injury consisting of collapsing glomerulopathy and focal segmental glomerulosclerosis in 17 (36.2%) patients. Two (4.3%) patients had acute vascular nephropathy, while eight (17%) had alternative diagnosis most likely unrelated to COVID-19. Acute tubular injury occurred almost invariably in the setting of severe forms of COVID-19, whereas patients with glomerular injury had various profiles of COVID-19 severity and collapsing glomerulopathy was only observed in patients harboring a combination of APOL1 risk variants. At last follow-up, 16 of the 30 patients who initially required dialysis were still on dialysis, and 9 died. The present study describes the spectrum of kidney lesions in patients with COVID-19. While acute tubular injury is correlated with COVID-19 severity, the pattern of glomerular injury is intimately associated with the expression of APOL1 risk variants.

Response to plasma exchange and graft survival in recurrent focal and segmental glomerulosclerosis after transplantation: does the time of recurrence matter? A retrospective study

Recurrence of primary focal and segmental glomerulosclerosis following kidney transplantation (rFSGS) is a frequent and severe disease. We studied the time to recurrence of FSGS and its impact on the response to plasma exchange (PE) and graft survival. Between 1990 and 2013, 2730 kidney transplants were performed, including 52 patients with a primary diagnosis of FSGS. Of these patients with primary FSGS, 34 (67%) developed rFSGS. We retrospectively divided these patients into two groups depending on the time to recurrence: early (up to three months after transplantation, n = 26) or late (more than three months after transplantation, n = 8). Survival did not significantly differ between the two groups. In cases of late recurrence, PE was started later and was performed less frequently, and remission was achieved after more PE sessions and longer PE treatment than for the early group (P = 0.01). In early recurrence, resistance to PE at 40 days was associated with no long-term response to PE. PE should be performed as soon as possible after rFSGS. Patients with late rFSGS need to be offered the same treatment regime as those with early rFSGS.