Current approaches to overcome recurrent focal segmental glomerulosclerosis after kidney transplantation.

PURPOSE OF REVIEW: Recurrent focal segmental glomerulosclerosis (FSGS) presents with nephrotic syndrome shortly after kidney transplantation. This review will overview the role of circulating permeability factors in disease pathogenesis and treatment options for recurrent FSGS. RECENT FINDINGS: Novel circulating permeability factors have been identified in serum samples. Current research is focused on detection of permeability factors as a marker of treatment response. Furthermore, novel monoclonal antibodies are being utilized to further induce remission. SUMMARY: Posttransplant recurrent FSGS can have a deleterious effect on allograft. Early detection of disease recurrence with prompt treatment is optimal for clinical remission. Plasmapheresis with anti-B cell therapy is considered the mainstay of treatment. Newer B cell therapies and detection of circulating factors in serum may help in providing targeted treatment in a subset of patients.

Longitudinal Outcomes of COVID-19-Associated Collapsing Glomerulopathy and Other Podocytopathies.

BACKGROUND: The long-term outcome of COVID-19-associated collapsing glomerulopathy is unknown. METHODS: We retrospectively identified 76 native kidney biopsies from patients with history of COVID-19 between March 2020 and April 2021. Presenting and outcome data were obtained for all 23 patients with collapsing glomerulopathy and for seven patients with noncollapsing podocytopathies. We performed APOL1 genotyping by Sanger sequencing, immunostaining for spike and nucleocapsid proteins, and in situ hybridization for SARS-CoV-2. RESULTS: The 23 patients with COVID-19-associated collapsing glomerulopathy were median age 57 years (range, 35-72), included 16 men, and were predominantly (91%) Black. Severity of COVID-19 was mild or moderate in most (77%) patients. All but one patient presented with AKI, 17 had nephrotic-range proteinuria, and six had nephrotic syndrome. Fourteen (61%) patients required dialysis at presentation. Among 17 patients genotyped, 16 (94%) were high-risk APOL1. Among 22 (96%) patients with median follow-up at 155 days (range, 30-412), 11 (50%) received treatment for COVID-19, and eight (36%) received glucocorticoid therapy for podocytopathy. At follow-up, 19 (86%) patients were alive, and 15 (68%) were dialysis free, including seven of 14 who initially required dialysis. The dialysis-free patients included 64% (seven of 11) of those treated for COVID-19 and 75% (six of eight) of those treated with glucocorticoids for podocytopathy. Overall, 36% achieved partial remission of proteinuria, 32% had no remission, and 32% reached combined end points of ESKD or death. Viral infection of the kidney was not detected. CONCLUSIONS: Half of 14 patients with COVID-19-associated collapsing glomerulopathy requiring dialysis achieved dialysis independence, but the long-term prognosis of residual proteinuric CKD remains guarded, indicating a need for more effective therapy.

Kidney Biopsy Findings in Patients with COVID-19.

BACKGROUND: Coronavirus disease 2019 (COVID-19) is thought to cause kidney injury by a variety of mechanisms. To date, pathologic analyses have been limited to patient reports and autopsy series. METHODS: We evaluated biopsy samples of native and allograft kidneys from patients with COVID-19 at a single center in New York City between March and June of 2020. We also used immunohistochemistry, in situ hybridization, and electron microscopy to examine this tissue for presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). RESULTS: The study group included 17 patients with COVID-19 (12 men, 12 black; median age of 54 years). Sixteen patients had comorbidities, including hypertension, obesity, diabetes, malignancy, or a kidney or heart allograft. Nine patients developed COVID-19 pneumonia. Fifteen patients (88%) presented with AKI; nine had nephrotic-range proteinuria. Among 14 patients with a native kidney biopsy, 5 were diagnosed with collapsing glomerulopathy, 1 was diagnosed with minimal change disease, 2 were diagnosed with membranous glomerulopathy, 1 was diagnosed with crescentic transformation of lupus nephritis, 1 was diagnosed with anti-GBM nephritis, and 4 were diagnosed with isolated acute tubular injury. The three allograft specimens showed grade 2A acute T cell-mediated rejection, cortical infarction, or acute tubular injury. Genotyping of three patients with collapsing glomerulopathy and the patient with minimal change disease revealed that all four patients had APOL1 high-risk gene variants. We found no definitive evidence of SARS-CoV-2 in kidney cells. Biopsy diagnosis informed treatment and prognosis in all patients. CONCLUSIONS: Patients with COVID-19 develop a wide spectrum of glomerular and tubular diseases. Our findings provide evidence against direct viral infection of the kidneys as the major pathomechanism for COVID-19-related kidney injury and implicate cytokine-mediated effects and heightened adaptive immune responses.

Directed Evolution of Scanning Unnatural-Protease-Resistant (SUPR) Peptides for in Vivo Applications.

Peptides typically have poor biostabilities, and natural sequences cannot easily be converted into drug-like molecules without extensive medicinal chemistry. We have adapted mRNA display to drive the evolution of highly stable cyclic peptides while preserving target affinity. To do this, we incorporated an unnatural amino acid in an mRNA display library that was subjected to proteolysis prior to selection for function. The resulting "SUPR (scanning unnatural protease resistant) peptide" showed ≈500-fold improvement in serum stability (t1/2 =160 h) and up to 3700-fold improvement in protease resistance versus the parent sequence. We extended this approach by carrying out SUPR peptide selections against Her2-positive cells in culture. The resulting SUPR4 peptide showed low-nanomolar affinity toward Her2, excellent specificity, and selective tumor uptake in vivo. These results argue that this is a general method to design potent and stable peptides for in vivo imaging and therapy.

Liver Disease-Associated Glomerulopathies.

Hepatitis B virus (HBV) and hepatitis C virus (HCV) infect a significant number of individuals globally and their extra-hepatic manifestations, including glomerular disease, are well established. Additionally, liver disease-associated IgA nephropathy is the leading cause of secondary IgA nephropathy with disease course varying from asymptomatic urinary abnormalities to progressive kidney injury. Herein we provide an updated review on the epidemiology, pathogenesis, clinical manifestations, and treatment of HBV- and HCV-related glomerulonephritis as well as IgA nephropathy in patients with liver disease. The most common HBV-related glomerulonephritis is membranous nephropathy, although membranoproliferative glomerulonephritis and podocytopathies have been described. The best described HCV-related glomerulonephritis is cryoglobulinemic glomerulonephritis occurring in about 30% of patients with mixed cryoglobulinemic vasculitis. The mainstay of treatment for HBV-GN and HCV-GN is antiviral therapy, with significant improvement in outcomes since the emergence of the direct-acting antivirals. However, cases with severe pathology and/or a more aggressive disease trajectory can be offered a course of immunosuppression, commonly anti-CD20 therapy, particularly in the case of cryoglobulinemic glomerulonephritis.

C3 Glomerulopathy Recurs Early after Kidney Transplantation in Serial Biopsies Performed within the First Two Years Post-Transplantation.

BACKGROUND: C3 glomerulopathy (C3G), which encompasses C3 glomerulonephritis (C3GN) and dense deposit disease (DDD), results from dysregulation of the alternative complement pathway. Data on disease recurrence after kidney transplantation is limited, and details on histologic features of recurrent C3G are scarce. We aimed to evaluate C3G recurrence in the allograft, with a focus on histologic presentation and progression. METHODS: We retrospectively analyzed 18 patients with native kidney failure attributed to C3G (12 C3GN and six DDD) who received a kidney transplant from January 2016 to January 2023. Demographic, genetic, clinical, and histologic data were studied. The Nanostring 770 genes immune profiling panel was used for transcriptomic analysis. Disease recurrence was the primary outcome. RESULTS: During a median (IQR) follow-up period of 37 (18, 56) months, C3G recurrence occurred in 16 (89%) of patients (11 with C3GN and five with DDD), at a median (IQR) of 33 (13, 141) days post-transplantation. Over a third (38%) of recurrent cases were detected in protocol biopsies, and only 31% of patients presented with >300 mg/g of proteinuria. Recurrence in index biopsies was mainly established through a combination of immunofluorescence and electron microscopy findings, while it showed only subtle histologic alterations and no characteristic transcriptomic signals. Over time, histologic chronicity indices increased, but all allografts were functioning at the end of follow-up. Patients with recurrence of C3GN and DDD showed overlapping immunofluorescence and electron microscopy findings and had similar recurrence rate and time to recurrence. CONCLUSIONS: The majority of patients with native kidney failure attributed to C3G developed disease recurrence very early after kidney transplantation, usually with minimal proteinuria, mild histologic alterations, and favorable short-term allograft survival. Immunofluorescence and electron microscopy played a crucial role in detecting early, sub-clinical recurrence of C3GN and DDD, which showed significant overlapping features.

A Rare Case of Granulomatous Interstitial Nephritis in a Patient With COVID-19.

Acute kidney injury (AKI) in patients with coronavirus disease 2019 (COVID-19) is common, especially among severely ill patients. While acute tubular necrosis (ATN) is one of the most common findings in published kidney biopsy series for patients with COVID-19 infections, a number of glomerular pathologies have been described as well. Among glomerular pathologies in COVID-19, COVID-19-Associated Collapsing Glomerulopathy (COVAN) remains the most common pattern of injury. Patients with 2 high-risk APOL1 alleles appear to be at increased risk for COVAN, similar to other forms of collapsing glomerulopathy such as HIV-Associated Nephropathy. Acute interstitial nephritis (AIN) is a less common finding in patients with COVID-19 and reported cases have been mild. Reports of a subtype of AIN, granulomatous interstitial nephritis (GIN), among COVID-19 patients are extremely rare and have not been reported in association with COVAN. Here, we report a case of COVAN associated with severe GIN.

Late Relapses of Membranous Nephropathy: A Case Series.

Background: Relapse of the nephrotic syndrome is co mmon among patients with primary membranous nephropathy (MN). Relapses of MN typically occur within a few years of achieving disease remission. There is limited description, to date, regarding patients with MN who have late relapse of MN, i.e., after >5 years of sustained disease remission. The objective of this case series was to report the clinical course of patients with MN who experience late relapse. Methods: We analyzed the patient database of the Glomerular Kidney Disease Center at Columbia University to identify patients seen at our center who had relapse of biopsy specimen-proven MN at least 5 years after achieving sustained disease remission. Results: We identified 16 patients with late relapse of MN. The median time in sustained remission before relapse was 10.2 (range, 7-29.0) years. Ten patients (63%) were diagnosed with late relapse on the basis of laboratory monitoring alone, without clinical symptoms of the nephrotic syndrome. Fourteen patients (88%) received immunosuppression during their initial presentation and late relapse. Patients had favorable long-term renal outcomes over a median 21 (range, 12-56) year follow-up period, with 14 patients (88%) in remission at study conclusion and a median decline in eGFR per year of -0.63 (range, -6.3 to 17.5) ml/min per 1.73 m2 per year. Conclusions: This case series highlights a previously underappreciated, and likely rare, outcome of MN, namely, late relapse. Patients who experience late relapse, and who thus have a longer time in sustained remission, may have a more favorable long-term renal outcome.

The Evolving Role of Calcineurin Inhibitors in Treating Lupus Nephritis.

The overall kidney survival among lupus nephritis patients has improved with currently used induction immunosuppression regimens of corticosteroids and either cyclophosphamide or mycophenolate mofetil; however, there still remains a significant number of lupus nephritis patients who do not achieve remission with these regimens. Investigators have looked at other immunosuppressive regimens for lupus nephritis, and there has been interest in the use of calcineurin inhibitors in this regard. Calcineurin inhibitors are potentially an attractive option because of their established ability to inhibit T cell function, attenuate proteinuria through non-immunologic means, and their safety in pregnancy and lactation. In this review, we discuss the findings and limitations of selected trials that evaluated the use of calcineurin inhibitors in the treatment of lupus nephritis, either with corticosteroids alone or as a component of multitarget therapy when combined with mycophenolate mofetil. There may be a role for calcineurin inhibitors among patients with heavy proteinuria, as well as younger patients with refractory lupus nephritis. The multitarget therapy trials reveal higher rates of remission compared with mycophenolate mofetil alone and cyclophosphamide; however, some trials highlight the possibility of more infectious adverse events. We discuss the need for further study of calcineurin inhibitors in more diverse patient populations and the need for trials with longer follow-up with "hard" endpoints beyond proteinuria reduction, such as worsening CKD or repeat protocol biopsies, given the calcineurin inhibitors ability to reduce proteinuria non-immunologically and thus increased rate of relapse when the drug is tapered. While there may indeed be a space for calcineurin inhibitors to help increase remission rates in lupus nephritis patients, more work is needed to help address the questions the studies available to date have yet to answer.

High rate of renal recovery in survivors of COVID-19 associated acute renal failure requiring renal replacement therapy.

INTRODUCTION: A large proportion of patients with COVID-19 develop acute kidney injury (AKI). While the most severe of these cases require renal replacement therapy (RRT), little is known about their clinical course. METHODS: We describe the clinical characteristics of COVID-19 patients in the ICU with AKI requiring RRT at an academic medical center in New York City and followed patients for outcomes of death and renal recovery using time-to-event analyses. RESULTS: Our cohort of 115 patients represented 23% of all ICU admissions at our center, with a peak prevalence of 29%. Patients were followed for a median of 29 days (2542 total patient-RRT-days; median 54 days for survivors). Mechanical ventilation and vasopressor use were common (99% and 84%, respectively), and the median Sequential Organ Function Assessment (SOFA) score was 14. By the end of follow-up 51% died, 41% recovered kidney function (84% of survivors), and 8% still needed RRT (survival probability at 60 days: 0.46 [95% CI: 0.36-0.56])). In an adjusted Cox model, coronary artery disease and chronic obstructive pulmonary disease were associated with increased mortality (HRs: 3.99 [95% CI 1.46-10.90] and 3.10 [95% CI 1.25-7.66]) as were angiotensin-converting-enzyme inhibitors (HR 2.33 [95% CI 1.21-4.47]) and a SOFA score >15 (HR 3.46 [95% CI 1.65-7.25). CONCLUSIONS AND RELEVANCE: Our analysis demonstrates the high prevalence of AKI requiring RRT among critically ill patients with COVID-19 and is associated with a high mortality, however, the rate of renal recovery is high among survivors and should inform shared-decision making.

Sparse NIR optimization method (SNIRO) to quantify analyte composition with visible (VIS)/near infrared (NIR) spectroscopy (350 nm-2500 nm).

Visual-Near-Infra-Red (VIS/NIR) spectroscopy has led the revolution in high-throughput phenotyping methods used to determine chemical and structural elements of organic materials. In the current state of the art, spectrophotometers used for imaging techniques are either very expensive or too large to be used as a field-operable device. In this study we developed a Sparse NIR Optimization method (SNIRO) that selects a pre-determined number of wavelengths that enable quantification of analytes in a given sample using linear regression. We compared the computed complexity time and the accuracy of SNIRO to Marten's test, to forward selection test and to LASSO all applied to the determination of protein content in corn flour and meat and octane number in diesel using publicly available datasets. In addition, for the first time, we determined the glucose content in the green seaweed Ulva sp., an important feedstock for marine biorefinery. The SNIRO approach can be used as a first step in designing a spectrophotometer that can scan a small number of specific spectral regions, thus decreasing, potentially, production costs and scanner size and enabling the development of field-operable devices for content analysis of complex organic materials.