Francesca Conserva

Background: Immunocompromised patients show an impaired vaccine response and remain at high risk of severe COVID-19, despite vaccination. Neutralizing monoclonal antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been developed for prophylaxis and treatment. The combination tixagevimab/cilgavimab (AZD7442) has been authorized for emergency use as pre-exposure prophylaxis for COVID-19, but data on safety and efficacy in kidney transplant recipients during the Omicron period are limited. Methods: We conducted a multicenter retrospective cohort study including 253 kidney transplant recipients, of whom 98 were treated with tixagevimab/cilgavimab 150 mg/150 mg and 155 who received only four doses of the BNT162b2 mRNA vaccine. Results: Only 13.3% of patients developed SARS-CoV-2 infection after the administration of tixagevimab/cilgavimab; in comparison, 34.2% of patients had been infected after the fourth dose of vaccine ( p = 0.00013). Most infected patients in the AZD7442 group remained asymptomatic (92.3% vs 54.7%), 7.7% had mild symptoms and none had severe disease, need for hospitalization or died, while in the control group, 9.4% of patients had moderate or severe disease ( p = 0.04). Using Kaplan–Meier curves we demonstrated that the controls presented early infection compared to the AZD7442 group ( p = 0.000014). No changes in eGFR or proteinuria, assessed before and after the administration, were observed. Conclusions: In conclusion, our study showed that tixagevimab/cilgavimab 150/150 mg is effective and safe in preventing infection and severe disease when administered to patients with weak or no response to COVID-19 vaccine. Graphical

Between 15–20% of patients with end stage renal disease (ESRD) do not know the cause of the primary kidney disease and can develop complications after kidney transplantation. We performed a genetic screening in 300 patients with kidney transplantation, or undiagnosed primary renal disease, in order to identify the primary disease cause and discriminate between overlapping phenotypes. We used a custom-made panel for next-generation sequencing (Agilent technology, Santa Clara, CA, USA), including genes associated with Fabry disease, podocytopaties, complement-mediated nephropathies and Alport syndrome-related diseases. We detected candidate diagnostic variants in genes associated with nephrotic syndrome and Focal Segmental Glomerulosclerosis (FSGS) in 29 out of 300 patients, solving about 10% of the probands. We also identified the same genetic cause of the disease (PAX2: c.1266dupC) in three family members with different clinical diagnoses. Interestingly we also found one female patient carrying a novel missense variant, c.1259C>A (p.Thr420Lys), in the GLA gene not previously associated with Fabry disease, which is in silico defined as a likely pathogenic and destabilizing, and associated with a mild alteration in GLA enzymatic activity. The identification of the specific genetic background may provide an opportunity to evaluate the risk of recurrence of the primary disease, especially among patient candidates living with a donor kidney transplant.

Background: COVID-19 in kidney transplant recipients is associated with high morbidity and mortality. In this study we aimed to evaluate: (i) the seroconversion rate after BNT162b2 (Pfizer-BioNTech) SARS-CoV-2 vaccine, (ii) factors associated with humoral response, (iii) clinical outcome of COVID-19 in kidney transplanted patients. Methods: We enrolled a cohort of 743 kidney transplant recipients followed up from March 2020 until April 2022. A subset of 336 patients, who received three-doses of SARS-CoV-2 vaccine, was analyzed in terms of kinetics of humoral immune response and compared to a control group of 94 healthcare workers. Antibody response was tested before vaccination (T ₀ ), 15 and 90 days after the second dose (T ₁ and T ₂ ), on the day of the third dose (T ₃ ) and one month after the third dose (T ₄ ). Results: We observed that 66 out of 743 subjects had COVID-19 infection pre-vaccination: 65.2% had severe symptoms, 27.3% were hospitalized (9 deaths), none were asymptomatic. After three doses, 51 patients had COVID-19 infection, 60.8% were asymptomatic, 27.5% reported mild symptoms, 3.9% showed severe symptoms, 7.8% were hospitalized (2 deaths). In the subset of 336 vaccinated patients, an antibody level > 0.8 U/ml was detected at T ₁ , that increased at T ₂ and T _3, peaking at T ₄ . Independent factors associated with a negative antibody titer at T ₄ were decreasing estimated glomerular filtration rate, time from transplantation, and antimetabolites (all p < 0.001) and age ( p = 0.007). Conclusions: The kinetics of humoral response after three doses of vaccine in kidney transplant patients is characterized by a late but effective immune response against SARS-CoV-2, reducing morbidity and mortality. Graphical

Kidney transplantation is the first-choice treatment for end-stage renal disease (ESRD). Kidney transplant recipients (KTRs) are at higher risk of experiencing a life-threatening event requiring intensive care unit (ICU) admission, mainly in the late post-transplant period (more than 6 months after transplantation). Urosepsis and bloodstream infections account for almost half of ICU admissions in this population; in addition, potential side effects related to immunosuppressive treatment should be accounted for cytotoxic and ischemic changes induced by calcineurin inhibitor (CNI), sirolimus/CNI-induced thrombotic microangiopathy and posterior reversible encephalopathy syndrome. Throughout the ICU stay, Acute Kidney Injury (AKI) incidence is common and ranges from 10% to 80%, and up to 40% will require renal replacement therapy. In-hospital mortality can reach 30% and correlates with acute illness severity and admission diagnosis. Graft survival is subordinated to baseline estimated glomerular filtration rate (eGFR), clinical presentation, disease severity and potential drug nephrotoxicity. The present review aims to define the impact of AKI events on short- and long-term outcomes in KTRs, focusing on the epidemiologic data regarding AKI incidence in this subpopulation; the pathophysiological mechanisms underlying AKI development and potential AKI biomarkers in kidney transplantation, graft and patients’ outcomes; the current diagnostic work up and management of AKI; and the modulation of immunosuppression in ICU-admitted KTRs.

Diabetic nephropathy (DN) is the most frequent cause of end-stage renal disease. Tubulointerstitial accumulation of lysine 63 (K63)-ubiquitinated (Ub) proteins is involved in the progression of DN fibrosis and correlates with urinary miR-27b-3p downregulation. We explored the renoprotective effect of an inhibitor of K63-Ub (NSC697923), alone or in combination with the ACE-inhibitor ramipril, in vitro and in vivo. Proximal tubular epithelial cells and diabetic DBA/2J mice were treated with NSC697923 and/or ramipril. K63-Ub protein accumulation along with α-SMA, collagen I and III, FSP-1, vimentin, p16^INK4A expression, SA-α Gal staining, Sirius Red, and PAS staining were measured. Finally, we measured the urinary albumin to creatinine ratio (uACR), and urinary miR-27b-3p expression in mice. NSC697923, both alone and in association with ramipril, in vitro and in vivo inhibited hyperglycemia-induced epithelial to mesenchymal transition by significantly reducing K63-Ub proteins, α-SMA, collagen I, vimentin, FSP-1 expression, and collagen III along with tubulointerstitial and glomerular fibrosis. Treated mice also showed recovery of urinary miR-27b-3p and restored expression of p16^INK4A. Moreover, NSC697923 in combination with ramipril demonstrated a trend in the reduction of uACR. In conclusion, we suggest that selective inhibition of K63-Ub, when combined with the conventional treatment with ACE inhibitors, might represent a novel treatment strategy to prevent the progression of fibrosis and proteinuria in diabetic nephropathy and we propose miR-27b-3p as a biomarker of treatment efficacy.

A specific subfamily within the E2 protein family is involved in the synthesis of noncanonical poly-ubiquitin chains, linked through lysine 63 residues. The role of lysine 63-linked polyubiquitylation in diseases has emerged only recently. Under physiological conditions, this process does not seem to be involved in the classical protein degradation by the proteasome, but it is involved in the regulation of intracellular signaling, DNA damage response, cellular trafficking, and lysosomal targeting. The alteration of this process has been described in a number of pathological conditions, including immune disorders, diabetes, and cancer. In this chapter, we will describe the role of lysine 63-linked ubiquitylation in the regulation of diverse signaling pathways involved in cell behavior. We will also describe some pathological conditions in which altered lysine 63-linked ubiquitylation has been referred to play an important role.

Diabetic nephropathy patients (DN) are characterized by increased lysine63 ubiquitination (Lys63-Ub) at the tubular level. Autophagy is deregulated under diabetic conditions, even though the molecular mechanisms and the consequences of this alteration need to be elucidated. The aim of this study was to investigate the link between Lys63-Ub and autophagy in DN and the involvement of these two processes in tubular cell fate. Immunohistochemistry of beclin-1, LC3, and p62 on kidney biopsies highlighted increased protein expression of all these autophagic factors at the tubular level in DN compared to other nephritis. Transmission electron microscopy confirmed the presence of diffuse vacuolization and autophago(lyso)somal structures in proximal tubular cells in DN. Accumulation of Lys63-Ub proteins in DN increased in accordance with the tubular damage and was associated to increased LC3 expression both in vivo and in vitro. Hyperglycemia (HG)-induced LC3 and p62 protein expression in HK2 cells together with Lys63-ubiquitinated proteins, and the inhibition of HG-induced Lys63-Ub by NSC697923 inhibitor, significantly reduced both LC3 and p62 expression. Moreover, in DN, those tubules expressing LC3 showed increased caspase-3 expression, supporting the hypothesis that deregulated autophagy induces apoptosis of tubular cells. In vitro, we confirmed a tight association between impaired autophagy, Lys63-Ub, and apoptosis since Lys63-Ub inhibition by NSC697923 abrogated HG-induced cell death and LC3 silencing also blocked hyperglycemia-induced caspase-3 activation. Our data suggested that prolonged hyperglycemia in diabetic patients can impair autophagy as a consequence of Lys63-Ub protein accumulation, thus promoting intracellular autophagic vesicles increase, finally leading to tubular cell death in DN.

INTRODUCTION AND AIMS: Diabetic Kidney Disease (DKD) is a heterogeneous disease that may include distinct histopathological petterns. While about 40% of the patients show the typical nodular Kimmelstiel-Wilson lesions (DN), the remaining cases may have atarteriolosclerotic changes and other primitive glomerulonephropathies (non DN CKD). Recent studies suggest a role of protein ubiquitination in DKD thus we tested the usefulness of urinary ubiquitinated proteins (ubi-prot) as novel biomarkers for differential diagnosis of DKD.

Article: The pathological role of the ubiquitination pathway in diabetic nephropathy - Minerva Medica 2018 February;109(1):53-67 - Minerva Medica - Journals