COVID-19-associated glomerulopathy and high-risk apol1 genotype; basis for a two-hit mechanism of injury? A narrative review on recent findings

Kidney is one of the most common organs affected by coronavirus disease 2019 (COVID-19) after the respiratory and immune systems. Among the renal parenchymal components, the tubulointerstitial compartment is presumed to be the prime target of injury in COVID-19. The main mechanism of renal tubular damage by COVID-19 is considered to be indirect, i.e., cytokine-mediated injury. A proportion of infected individuals mount a strong inflammatory response to the virus by an exaggerated immune response of the body, namely cytokine storm. Sudden and massive release of cytokines may lead to serious systemic hyper-inflammation and renal tubular injury and inflammation resulting in acute renal failure. In addition, a number of cases of glomerulopathies, particularly collapsing glomerulopathy (CG) have been reported, predominantly in people of African ancestry, as a rare form of kidney involvement by SARS-CoV-2 that may originate from the background genetic susceptibility in this population complicated by the second hit of SARS-CoV-2 infection, either directly or indirectly. It is noteworthy that renal injury in COVID-19 could be severe in individuals of African origin due to the aforementioned genetic susceptibility, especially the presence of high-risk apolipoprotein L1 (APOL1) genotypes. Although the exact mechanism of kidney injury by SARS-CoV-2 is as yet unknown, multiple mechanisms are likely involved in renal damage caused by this virus. This review was aimed to summarize the salient points of pathogenesis of kidney injury, particularly glomerular injury in COVID-19 disease in the light of published data. A clear understanding of these is imperative for the proper management of these cases. For this review, a search was made of Google Scholar, Web of Science, Scopus, EBSCO and PubMed for finding English language articles related to COVID-19, kidney injury and glomerulopathy. From the information given in finally selected papers, the key aspects regarding glomerular involvement in COVID-19 were drawn out and are presented in this descriptive review

Heat shock protein 27 (HSP27): biomarker of disease and therapeutic target

<p><b>Abstract</b></p> <p>Heat shock protein 27 (HSP27) is a multidimensional protein which acts as a protein chaperone and an antioxidant and plays a role in the inhibition of apoptosis and actin cytoskeletal remodeling. In each of these capacities, HSP27 has been implicated in different disease states playing both protective and counter-protective roles. The current review presents HSP27 in multiple disease contexts: renal injury and fibrosis, cancer, neuro-degenerative and cardiovascular disease, highlighting its role as a potential biomarker and therapeutic target.</p

Graft Function Variability and Slope and Kidney Transplantation Outcomes

Introduction: It is critical to identify kidney transplant recipients (KTRs) at higher risk for adverse outcomes, to focus on monitoring and interventions to improve outcomes. We examined the associations between graft function variability and long-term outcomes in KTRs in an observational study. Methods: We identified 2919 KTRs in the Wisconsin Allograft Recipient Database (WisARD) who had a functioning allograft 2 years posttransplantation and at least 3 outpatient measurements of estimated glomerular filtration rate (eGFR) from 1 to 2 years posttransplantation. Graft function slope was calculated from a linear regression of eGFR, and variability was defined as the coefficient of variation around this regression line. Associations of eGFR variability and slope with death, graft failure, cardiovascular events, and acute rejection were estimated. Results: Compared to the lowest quartile, the highest quartile of eGFR variability was associated with a higher risk of death (adjusted hazard ratio [HR] = 1.85; 95% CI = 1.23−2.76), but not with a higher risk of graft failure (subhazard ratio = 1.16; 95% CI = 0.85−1.58), independent of eGFR and slope of eGFR. Greater eGFR variability was associated with higher risk of cardiovascular- and infection-related death and cardiovascular events but not malignancy-related death or allograft rejection. Including variability of eGFR significantly improved prediction of mortality but not prediction of graft failure. Conclusion: Variability of eGFR is independently associated with risk of death, especially cardiovascular disease−related death and cardiovascular events, but not graft failure. Variability of eGFR may help identify KTRs at higher risk for death and cardiovascular events

Chronic Active Antibody-mediated Rejection: Opportunity to Determine the Role of Interleukin-6 Blockade

Chronic active antibody-mediated rejection (caAMR) is arguably the most important cause of late kidney allograft failure. However, there are no US Food and Drug Administration (FDA)-approved treatments for acute or chronic AMR and there is no consensus on effective treatment. Many trials in transplantation have failed because of slow and/or inadequate enrollment, and no new agent has been approved by the FDA for transplantation in over a decade. Several lines of evidence suggest that interleukin-6 is an important driver of AMR, and clazakizumab, a humanized monoclonal antibody that neutralizes interleukin-6, has shown promising results in phase 2 studies. The IMAGINE trial (Interleukin-6 Blockade Modifying Antibody-mediated Graft Injury and Estimated Glomerular Filtration Rate Decline) (NCT03744910) is the first to be considered by the FDA using a reasonably likely surrogate endpoint (slope of estimated glomerular filtration rate decline \u3e1 y) for accelerated approval and is the only ongoing clinical trial for the treatment of chronic rejection. This trial offers us the opportunity to advance the care for our patients in need, and this article is a call to action for all transplant providers caring for patients with caAMR

Desensitization and treatment with APRIL/BLyS blockade in rodent kidney transplant model.

Alloantibody represents a significant barrier in kidney transplant through the sensitization of patients prior to transplant through antibody mediated rejection (ABMR). APRIL BLyS are critical survival factors for mature B lymphocytes plasma cells, the primary source of alloantibody. We examined the effect of APRIL/BLyS blockade via TACI-Ig (Transmembrane activator calcium modulator cyclophilin lig interactor-Immunoglobulin) in a preclinical rodent model as treatment for both desensitization ABMR. Lewis rats were sensitized with Brown Norway (BN) blood for 21 days. Following sensitization, animals were then sacrificed or romized into kidney transplant (G4, sensitized transplant control); desensitization with TACI-Ig followed by kidney transplant (G5, sensitized + pre-transplant TACI-Ig); kidney transplant with post-transplant TACI-Ig for 21 days (G6, sensitized + post-transplant TACI-Ig); desensitization with TACI-Ig followed by kidney transplant post-transplant TACI-Ig for 21 days (G7, sensitized + pre- post-transplant TACI-Ig). Animals were sacrificed on day 21 post-transplant tissues were analyzed using flow cytometry, IHC, ELISPOT, RT-PCR. Sensitized animals treated with APRIL/BLyS blockade demonstrated a significant decrease in marginal zone non-switched B lymphocyte populations (p<0.01). Antibody secreting cells were also significantly reduced in the sensitized APRIL/BLyS blockade treated group. Post-transplant APRIL/BLyS blockade treated animals were found to have significantly less C4d deposition less ABMR as defined by Banff classification when compared to groups receiving APRIL/BLyS blockade before transplant or both before after transplant (p<0.0001). The finding of worse ABMR in groups receiving APRIL/BLyS blockade before both before after transplant may indicate that B lymphocyte depletion in this setting also resulted in regulatory lymphocyte depletion resulting in a worse rejection. Data presented here demonstrates that the targeting of APRIL BLyS can significantly deplete mature B lymphocytes, antibody secreting cells, effectively decrease ABMR when given post-transplant in a sensitized animal model

Autologous Mesenchymal Stromal Cells Prevent Transfusion-elicited Sensitization and Upregulate Transitional and Regulatory B Cells

Background. We hypothesized that immunomodulatory properties of mesenchymal stromal cells (MSC) may be considered for desensitization. Methods. Autologous or allogeneic bone marrow derived MSC were infused via tail vein at 0.5 M (0.5 × 106), 1 M, or 2 M cells/dose on days −2, 3, 6, 9, 12 (prevention) or 14, 17, 20, 23, 26 (treatment) relative to transfusion in a Brown Norway to Lewis rat model (10 groups total, n = 6 per group). Results. At 4 weeks, pooled analyses demonstrated that autologous and allogeneic MSC were equally effective in reducing IgG1 and IgG2a de novo donor-specific antibody (dnDSA, P < 0.001). Dose-response studies indicated that moderate-dose MSC (5 M total) was most effective in reducing IgG1, IgG2a, and IgG2c dnDSA (P ≤ 0.01). Time course studies determined that preventive and treatment strategies were equally effective in reducing IgG1 and IgG2a dnDSA (P ≤ 0.01). However, individual group analyses determined that moderate-dose (5 M) treatment with autologous MSC was most effective in reducing IgG1, IgG2a, and IgG2c dnDSA (P ≤ 0.01). In this group, dnDSA decreased after 1 week of treatment; regulatory B cells increased in the spleen and peripheral blood mononuclear cells; and transitional B cells increased in the spleen, peripheral blood mononuclear cells, and bone marrow (P < 0.05 for all). Conclusions. Our findings indicate that autologous MSC prevent transfusion-elicited sensitization and upregulate transitional, and regulatory B cells. Additional studies are needed to determine the biological relevance of these changes after kidney transplantation