CD4+ T Cell-Derived NGAL Modifies the Outcome of Ischemic Acute Kidney Injury.

CD4+ T cells mediate the pathogenesis of ischemic and nephrotoxic acute kidney injury (AKI). However, the underlying mechanisms of CD4+ T cell-mediated pathogenesis are largely unknown. We therefore conducted unbiased RNA-sequencing to discover novel mechanistic pathways of kidney CD4+ T cells after ischemia compared with normal mouse kidney. Unexpectedly, the lipocalin-2 (Lcn2) gene, which encodes neutrophil gelatinase-associated lipocalin (NGAL) had the highest fold increase (∼60). The NGAL increase in CD4+ T cells during AKI was confirmed at the mRNA level with quantitative real-time PCR and at the protein level with ELISA. NGAL is a potential biomarker for the early detection of AKI and has multiple potential biological functions. However, the role of NGAL produced by CD4+ T cells is not known. We found that ischemic AKI in NGAL knockout (KO) mice had worse renal outcomes compared with wild-type (WT) mice. Adoptive transfer of NGAL-deficient CD4+ T cells from NGAL KO mice into CD4 KO or WT mice led to worse renal function than transfer of WT CD4+ T cells. In vitro-simulated ischemia/reperfusion showed that NGAL-deficient CD4+ T cells express higher levels of IFN-γ mRNA compared with WT CD4+ T cells. In vitro differentiation of naive CD4+ T cells to Th17, Th1, and Th2 cells led to significant increase in Lcn2 expression. Human kidney CD4+ T cell NGAL also increased significantly after ischemia. These results demonstrate an important role for CD4+ T cell NGAL as a mechanism by which CD4+ T cells mediate AKI and extend the importance of NGAL in AKI beyond diagnostics.

Exosome-based delivery of super-repressor IκBα ameliorates kidney ischemia-reperfusion injury.

Ischemia-reperfusion injury is a major cause of acute kidney injury. Recent studies on the pathophysiology of ischemia-reperfusion-induced acute kidney injury showed that immunologic responses significantly affect kidney ischemia-reperfusion injury and repair. Nuclear factor (NF)-ĸB signaling, which controls cytokine production and cell survival, is significantly involved in ischemia-reperfusion-induced acute kidney injury, and its inhibition can ameliorate ischemic acute kidney injury. Using EXPLOR, a novel, optogenetically engineered exosome technology, we successfully delivered the exosomal super-repressor inhibitor of NF-ĸB (Exo-srIĸB) into B6 wild type mice before/after kidney ischemia-reperfusion surgery, and compared outcomes with those of a control exosome (Exo-Naïve)-injected group. Exo-srIĸB treatment resulted in lower levels of serum blood urea nitrogen, creatinine, and neutrophil gelatinase-associated lipocalin in post-ischemic mice than in the Exo-Naïve treatment group. Systemic delivery of Exo-srIĸB decreased NF-ĸB activity in post-ischemic kidneys and reduced apoptosis. Post-ischemic kidneys showed decreased gene expression of pro-inflammatory cytokines and adhesion molecules with Exo-srIĸB treatment as compared with the control. Intravital imaging confirmed the uptake of exosomes in neutrophils and macrophages. Exo-srIĸB treatment also significantly affected post-ischemic kidney immune cell populations, lowering neutrophil, monocyte/macrophage, and T cell frequencies than those in the control. Thus, modulation of NF-ĸB signaling through exosomal delivery can be used as a novel therapeutic method for ischemia-reperfusion-induced acute kidney injury.

Association of active oncologic treatment and risk of death in cancer patients with COVID-19: a systematic review and meta-analysis of patient data.

BACKGROUND: Cancer patients suffer from worse coronavirus disease-2019 (COVID-19) outcomes. Whether active oncologic treatment is an additional risk factor in this population remains unclear. Therefore, here we have conducted a systematic review and meta-analysis to summarize the existing evidence for the effect of active oncologic treatment on COVID-19 outcomes. METHODS: Systematic search of databases (PubMed, Embase) was conducted for studies published from inception to July 1, 2020, with a subsequent search update conducted on 10 October 2020. In addition, abstracts and presentations from major conference proceedings (ASCO, ESMO, AACR) as well as pre-print databases (medxriv, bioxriv) were searched. Retrospective and prospective studies reporting clinical outcomes in cancer patients with laboratory confirmation or clinical diagnosis of COVID-19 and details of active or recent oncologic treatment were selected. Random-effects model was applied throughout meta-analyses. Summary outcome measure was the pooled odds ratio (OR) of death for active cancer therapy versus no active cancer therapy for each of the following modalities: recent surgery, chemotherapy, targeted therapy, immunotherapy, or chemoimmunotherapy. RESULTS: Sixteen retrospective and prospective studies (3558 patients) were included in the meta-analysis. Active chemotherapy was associated with higher risk of death compared to no active chemotherapy (OR, 1.60, 95% CI, 1.14-2.23). No significant association with risk of death was identified for active targeted therapy, immunotherapy, chemoimmunotherapy, or recent surgery. Meta-analysis of multivariate adjusted OR of death for active chemotherapy was consistently associated with higher risk of death compared to no active chemotherapy (OR, 1.42, 95% CI, 1.01-2.01). CONCLUSIONS: Active chemotherapy appears to be associated with higher risk of death in cancer patients with COVID-19. Further research is necessary to characterize the complex interactions between active cancer treatment and COVID-19.

TCR+CD4-CD8- (double negative) T cells protect from cisplatin-induced renal epithelial cell apoptosis and acute kidney injury.

Acute kidney injury (AKI) due to cisplatin is a significant problem that limits its use as an effective chemotherapeutic agent. T cell receptor+CD4-CD8- double negative (DN) T cells constitute the major T cell population in the human and mouse kidney, express programmed cell death protein (PD)-1, and protect from ischemic AKI. However, the pathophysiological roles of DN T cells in cisplatin-induced AKI is unknown. In this study, wild-type mice were treated with cisplatin (30 mg/kg) or vehicle, and the effects on kidney DN T cell numbers and function were measured. In vitro experiments evaluated effects of kidney DN T cells on cisplatin-induced apoptosis and PD ligand 1 (PD-L1) in renal epithelial cells. Adoptive transfer experiments assessed the therapeutic potential of DN T cells during cisplatin-induced AKI. Our results show that kidney DN T cell population increased at 24 h and declined by 72 h after cisplatin treatment. Cisplatin treatment increased kidney DN T cell proliferation, apoptosis, CD69, and IL-10 expression, whereas CD62L, CD44, IL-17A, interferon-γ, and TNF-α were downregulated. Cisplatin treatment decreased both PD-1 and natural killer 1.1 subsets of kidney DN T cells with a pronounced effect on the PD-1 subset. In vitro kidney DN T cell coculture decreased cisplatin-induced apoptosis in kidney proximal tubular epithelial cells, increased Bcl-2, and decreased cleaved caspase 3 expression. Cisplatin-induced expression of PD ligand 1 was reduced in proximal tubular epithelial cells cocultured with DN T cells. Adoptive transfer of DN T cells attenuated kidney dysfunction and structural damage from cisplatin-induced AKI. These results demonstrate that kidney DN T cells respond rapidly and play a protective role during cisplatin-induced AKI.

KEAP1 Editing Using CRISPR/Cas9 for Therapeutic NRF2 Activation in Primary Human T Lymphocytes.

Oxidant stress modifies T lymphocyte activation and function. Previous work demonstrated that murine T cell-specific kelch like-ECH-associated protein 1 (Keap1) deletion enhances antioxidant capacity and protects from experimental acute kidney injury. In this study, we used CRISPR technology to develop clinically translatable human T cell-specific KEAP1 deletion. Delivery of KEAP1 exon 2 specific Cas9:guide RNA in Jurkat T cells led to significant (∼70%) editing and upregulation of NRF2-regulated antioxidant genes NADPH dehydrogenase quinone 1 (NQO1) (up to 11-fold), heme oxygenase 1 (HO1) (up to 11-fold), and GCLM (up to 2-fold). In primary human T cells, delivery of KEAP1 exon 2 target site 2-specific ATTO 550-labeled Cas9:guide RNA edited KEAP1 in ∼40% cells and significantly (p ≤ 0.04) increased NQO1 (16-fold), HO1 (9-fold), and GCLM (2-fold) expression. To further enrich KEAP1-edited cells, ATTO 550-positive cells were sorted 24 h after electroporation. Assessment of ATTO 550-positive cells showed KEAP1 editing in ∼55% cells. There was no detectable off-target cleavage in the top three predicted genes in the ATTO 550-positive cells. Gene expression analysis found significantly (p ≤ 0.01) higher expression of NQO1 mRNA in ATTO 550-positive cells compared with control cells. Flow cytometric assessment showed increased (p ≤ 0.01) frequency of CD4-, CD25-, and CD69-expressing KEAP1 edited cells whereas frequency of CD8- (p ≤ 0.01) and IL-17- (p ≤ 0.05) expressing cells was reduced compared with control cells. Similar experimental conditions resulted in significant KEAP1 editing, increased antioxidant gene expression, and frequency of CD69 and IL-10 positive cells in highly enriched KEAP1-edited regulatory T cells. KEAP1-edited T cells could potentially be used for treating multiple human diseases.

Activation and Proliferation of PD-1+ Kidney Double-Negative T Cells Is Dependent on Nonclassical MHC Proteins and IL-2.

BACKGROUND: CD4- CD8- double-negative (DN) αß T cells with innate-like properties represent a significant component of T cells in human and mouse kidneys. They spontaneously proliferate in the steady state and protect against ischemic AKI. However, the mechanisms regulating DN T cell homeostasis and responses to external danger signals from "sterile" inflammation remain poorly understood. METHODS: We used knockout mice, functional assays, and an established ischemic AKI model to investigate the role of various MHC class I and II molecules in regulating kidney DN T cells. We also studied human nephrectomy samples. RESULTS: Deficiency of ß2m-dependent MHC class I (but not MHC class II) molecules led to significant reduction in frequency or absolute numbers of kidney DN T cells due to impaired activation, proliferation, increased apoptosis, and loss of an NK1.1+ subset of DN T cells. The remaining DN T cells in ß2m knockout mice mainly comprised a programmed cell death protein-1 receptor (PD-1+) subset that depends on IL-2 provided by conventional T cells for optimal homeostasis. However, this PD-1+ subset remained highly responsive to changes in milieu, demonstrated by responses to infused lymphocytes. It was also the major responder to ischemic AKI; the NK1.1+ subset and CD8+ T cells had minimal responses. We found both DN T cell subsets in normal and cancerous human kidneys, indicating possible clinical relevance. CONCLUSIONS: DN T cells, a unique population of kidney T cells, depend on nonclassical ß2m molecules for homeostasis and use MHC-independent mechanisms to respond to external stimuli. These results have important implications for understanding the role these cells play during AKI and other immune cell-mediated kidney diseases.

Distant Organ Dysfunction in Acute Kidney Injury: A Review.

Acute kidney injury (AKI) is common in critically ill patients and is associated with increased morbidity and mortality. Dysfunction of other organs is an important cause of poor outcomes from AKI. Ample clinical and epidemiologic data show that AKI is associated with distant organ dysfunction in lung, heart, brain, and liver. Recent advancements in basic and clinical research have demonstrated physiologic and molecular mechanisms of distant organ interactions in AKI, including leukocyte activation and infiltration, generation of soluble factors such as inflammatory cytokines/chemokines, and endothelial injury. Oxidative stress and production of reactive oxygen species, as well as dysregulation of cell death in distant organs, are also important mechanism of AKI-induced distant organ dysfunction. This review updates recent clinical and experimental findings on organ crosstalk in AKI and highlights potential molecular mechanisms and therapeutic targets to improve clinical outcomes during AKI.

Low serum intact parathyroid hormone level is an independent risk factor for overall mortality and major adverse cardiac and cerebrovascular events in incident dialysis patients.

UNLABELLED: Abnormal bone dynamics is a major risk factor for cardiovascular disease in patients with chronic kidney disease. The level of serum intact parathyroid hormone (iPTH) is widely used as a bone dynamic marker. We investigated the effect of the mean level of serum iPTH on overall mortality and cardiovascular outcomes in incident dialysis patients. PURPOSE: Chronic kidney disease-mineral bone disorder (CKD-MBD) is a major risk factor for cardiovascular disease (CVD) in patients with end-stage renal disease (ESRD). CKD-MBD is classified as low- or high-turnover bone disease according to the bone dynamics; both are related to vascular calcification in ESRD. To evaluate the prognostic value of abnormal serum parathyroid hormone (PTH) levels on ESRD patients, we investigated the effects of time-averaged serum intact PTH (TA-iPTH) levels on overall mortality and major adverse cardiac and cerebrovascular events (MACCEs) in incident dialysis patients. METHODS: Four hundred thirteen patients who started dialysis between January 2009 and September 2013 at Yonsei University Health System were enrolled. The patients were divided into three groups according to TA-iPTH levels during the 12 months after the initiation of dialysis: group 1, <65 pg/ml; group 2, 65-300 pg/ml; and group 3, >300 pg/ml. Cox regression analyses were performed to determine the prognostic value of TA-iPTH for overall mortality and MACCEs. RESULTS: The mean age of the patients was 57 ± 15 years, and 222 patients (54 %) were men. During the median follow-up of 40.8 ± 29.3 months, 49 patients (12 %) died, and MACCEs occurred in 55 patients (13 %). The multivariate Cox regression analyses demonstrated that a low TA-iPTH level was an independent risk factor for both overall mortality (group 2 as reference; group 1: hazard ratio (HR) = 2.06, 95 % confidence interval (CI) = 1.11-3.83, P = 0.023) and MACCEs (HR = 1.82, 95 % CI = 1.04-3.20, P = 0.036) in incident dialysis patients after adjustment for confounding factors. CONCLUSION: Low serum TA-iPTH is a useful clinical marker of both overall mortality and MACCEs in patients undergoing incident dialysis, mediated by vascular calcification.

Serum Ferritin Predicts Mortality Regardless of Inflammatory and Nutritional Status in Patients Starting Dialysis: A Prospective Cohort Study.

BACKGROUND: The impact of serum ferritin on prognosis in patients starting hemodialysis (HD) is not fully elucidated. METHODS: A prospective cohort of 946 incident HD patients from 26 dialysis centers in Korea was selected for this study. Patients were divided into tertiles according to natural logarithm (Ln) ferritin concentrations. RESULTS: During a median follow-up of 39 months, 88 (9.3%) patients died. Multivariate Cox proportional hazard analysis demonstrated that Ln ferritin was independently associated with an increase in cardiovascular mortality risk (hazard ratio (HR) 1.604, 95% CI 1.040-2.474, p = 0.033), infection-related mortality risk (HR 1.916, 95% CI 1.056-3.476, p = 0.032), and all-cause mortality risk (HR 1.547, 95% CI 1.156-2.069, p = 0.003). CONCLUSION: Serum ferritin levels at the time of HD commencement were a significant independent risk factor for mortality regardless of systemic inflammation and nutritional status. Therefore, elevated serum ferritin levels could be an effective indicator for prognosis.

Narrative Review of Immunomodulatory and Anti-inflammatory Effects of Sodium-Glucose Cotransporter 2 Inhibitors: Unveiling Novel Therapeutic Frontiers.

Sodium-glucose cotransporter 2 inhibitors (SGLT2 inhibitors) have evolved from their initial role as antidiabetic drugs to garner recognition for their remarkable cardio-protective and reno-protective attributes. They have become a crucial component of therapeutic guidelines for congestive heart failure and proteinuric chronic kidney disease (CKD). These benefits extend beyond glycemic control, because improvements in cardiovascular and renal outcomes occur swiftly. Recent studies have unveiled the immunomodulatory properties of SGLT2 inhibitors; thus, shedding light on their potential to influence the immune system and inflammation. This comprehensive review explores the current state of knowledge regarding the impact of SGLT2 inhibitors on the immune system and inflammation, focusing on preclinical and clinical evidence. The review delves into their antiinflammatory and immunomodulating effects, offering insights into clinical implications, and exploring emerging research areas related to their prospective immunomodulatory impact.

Kidney Immune Cell Characterization of Humanized Mouse Models.

Experimental studies often fail to translate to clinical practice. Humanized mouse models are an important tool to close this gap. We immunophenotyped the kidneys of NOG (EXL) and NSG mouse strains engrafted with human CD34 + hematopoietic stem cells or PBMCs and compared with immune cell composition of normal human kidney. Human CD34 + hematopoietic stem cell engraftment results in steady renal immune cell populations in mouse kidney with key similarities in composition compared with human kidney. Successful translation of experimental mouse data to human diseases is limited because of biological differences and imperfect disease models. Humanized mouse models are being used to bring murine models closer to humans. However, data for application in renal immune cell-mediated diseases are rare. We therefore studied immune cell composition of three different humanized mouse kidneys and compared them with human kidney. NOG and NOGEXL mice engrafted with human CD34 + hematopoietic stem cells were compared with NSG mice engrafted with human PBMCs. Engraftment was confirmed with flow cytometry, and immune cell composition in kidney, blood, spleen, and bone marrow was analyzed in different models. The results from immunophenotyping of kidneys from different humanized mouse strains were compared with normal portions of human kidneys. We found significant engraftment of human immune cells in blood and kidney of all tested models. huNSG mice showed highest frequencies of hTCR + cells compared with huNOG and huNOGEXL in blood. huNOGEXL was found to have the highest hCD4 + frequency among all tested models. Non-T cells such as hCD20 + and hCD11c + cells were decreased in huNSG mice compared with huNOG and huNOGEXL. Compared with normal human kidney, huNOG and huNOGEXL mice showed representative immune cell composition, rather than huNSG mice. In summary, humanization results in immune cell infiltration in the kidney with variable immune cell composition of tested humanized mouse models and partially reflects normal human kidneys, suggesting potential use for translational studies.

A spurious elevation of serum creatinine level in a patient with Crohn's disease without histologic kidney damage: a case report and review of the literature.

Patients with inflammatory bowel disease (IBD) are prone to develop kidney injury. Renal involvement in IBD patients is usually diagnosed by the measurement of serum creatinine and the estimation of the glomerular filtration rate. We describe a patient with IBD who presented with large fluctuations in his serum creatinine level (~3.0-fold) without significant histologic abnormalities and with a normal cystatin C level. This appears to be related to a high-protein diet and intermittent fasting. Even though the impact of a high-protein diet on mild elevations of the serum creatinine level has been described, large fluctuations in serum creatinine from diet alone, as seen in this case, have never been reported, raising the question about the potential contribution of inflamed bowel on gut absorption or metabolism of creatinine. This case highlights the importance of a detailed history, including the dietary habits, when encountering a patient with increased serum creatinine level, and careful interpretation of serum creatinine in a patient with a creatinine high-protein diet or underlying IBD.

T Cell Nrf2/Keap1 Gene Editing Using CRISPR/Cas9 and Experimental Kidney Ischemia-Reperfusion Injury.

Aims: T cells play pathophysiologic roles in kidney ischemia-reperfusion injury (IRI), and the nuclear factor erythroid 2-related factor 2/kelch-like ECH-associated protein 1 (Nrf2/Keap1) pathway regulates T cell responses. We hypothesized that clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9)-mediated Keap1-knockout (KO) augments Nrf2 antioxidant potential of CD4+ T cells, and that Keap1-KO CD4+ T cell immunotherapy protects from kidney IRI. Results: CD4+ T cell Keap1-KO resulted in significant increase of Nrf2 target genes NAD(P)H quinone dehydrogenase 1, heme oxygenase 1, glutamate-cysteine ligase catalytic subunit, and glutamate-cysteine ligase modifier subunit. Keap1-KO cells displayed no signs of exhaustion, and had significantly lower levels of interleukin 2 (IL2) and IL6 in normoxic conditions, but increased interferon gamma in hypoxic conditions in vitro. In vivo, adoptive transfer of Keap1-KO CD4+ T cells before IRI improved kidney function in T cell-deficient nu/nu mice compared with mice receiving unedited control CD4+ T cells. Keap1-KO CD4+ T cells isolated from recipient kidneys 24 h post IR were less activated compared with unedited CD4+ T cells, isolated from control kidneys. Innovation: Editing Nrf2/Keap1 pathway in murine T cells using CRISPR/Cas9 is an innovative and promising immunotherapy approach for kidney IRI and possibly other solid organ IRI. Conclusion: CRISPR/Cas9-mediated Keap1-KO increased Nrf2-regulated antioxidant gene expression in murine CD4+ T cells, modified responses to in vitro hypoxia and in vivo kidney IRI. Gene editing targeting the Nrf2/Keap1 pathway in T cells is a promising approach for immune-mediated kidney diseases.

Therapeutic application of extracellular vesicles for various kidney diseases: a brief review.

Extracellular vesicles (EVs) released from different types of kidney cells under physiologic conditions contribute to homeostasis maintenance, immune-modulation, and cell-to-cell communications. EVs can also negatively affect the progression of renal diseases through their pro-inflammatory, pro-fibrotic, and tumorigenic potential. Inhibiting EVs by blocking their production, release, and uptake has been suggested as a potential therapeutic mechanism based on the significant implication of exosomes in various renal diseases. On the other hand, stem cell-derived EVs can ameliorate tissue injury and mediate tissue repair by ameliorating apoptosis, inflammation, and fibrosis while promoting angiogenesis and tubular cell proliferation. Recent advancement in biomedical engineering technique has made it feasible to modulate the composition of exosomes with diverse biologic functions, making EV one of the most popular drug delivery tools. The objective of this review was to provide updates of recent clinical and experimental findings on the therapeutic potential of EVs in renal diseases and discuss the clinical applicability of EVs in various renal diseases. [BMB Reports 2022; 55(1): 3-10].

Association of Glycosylated Hemoglobin Level and Cancer-Related Mortality in Patients without Diabetes.

BACKGROUND: Previous studies have reported that abnormal glucose metabolism is associated with poor cancer outcomes. Glycated hemoglobin A1c (HbA1c) is an important indicator of glucose metabolism. This study aimed to investigate the relationship between nondiabetic HbA1c levels and cancer-related mortality. METHODS: This was a retrospective cohort study of Koreans who attended an annual or biennial health checkup program. The study group was categorized based on the quintile of HbA1c level (Q1, 3.0-5.1%; Q2, 5.2-5.3%; Q3, 5.4%; Q4, 5.5-5.6%, Q5, 5.7-6.4%). Cancer-related mortality was determined using the mortality data from the Korea National Statistical Office. Participants with an established diagnosis of diabetes or cancer were excluded. Cancer-related mortality was assessed depending on each HbA1c level with adjustment for factors that could influence mortality. RESULTS: A total of 589,457 participants were included in this study. During a median follow-up duration of 6.99 years, 1712 cancer-related deaths were reported. The risk of cancer-related mortality was significantly higher in the Q5 group (hazard ratio (HR) 1.23, range 1.02-1.47 in model 1; HR 1.25, range 1.04-1.50 in model 2). HbA1c levels were linearly associated with cancer-related deaths (Ptrend = 0.021 in model 1; 0.013 in model 2). HbA1c level and colorectal, stomach, and lung cancer mortality exhibited a positive relationship, whereas liver cancer-related mortality showed an inverse relationship with HbA1c level (Ptrend = 0.001). CONCLUSIONS: Our study showed that abnormal glucose metabolism is significantly associated with cancer-related mortality, and its relationship varies with each type of cancer.

Extracellular vesicles in kidneys and their clinical potential in renal diseases.

Extracellular vesicles (EVs), such as exosomes and microvesicles, are cell-derived lipid bilayer membrane particles, which deliver information from host cells to recipient cells. EVs are involved in various biological processes including the modulation of the immune response, cell-to-cell communications, thrombosis, and tissue regeneration. Different types of kidney cells are known to release EVs under physiologic as well as pathologic conditions, and recent studies have found that EVs have a pathophysiologic role in different renal diseases. Given the recent advancement in EV isolation and analysis techniques, many studies have shown the diagnostic and therapeutic potential of EVs in various renal diseases, such as acute kidney injury, polycystic kidney disease, chronic kidney disease, kidney transplantation, and renal cell carcinoma. This review updates recent clinical and experimental findings on the role of EVs in renal diseases and highlights the potential clinical applicability of EVs as novel diagnostics and therapeutics.

Increased risk of acute kidney injury in coronavirus disease patients with renin-angiotensin-aldosterone-system blockade use: a systematic review and meta-analysis.

Acute kidney injury (AKI) is a severe complication of coronavirus disease (COVID-19) that negatively affects its outcome. Concern had been raised about the potential effect of renin-angiotensin-aldosterone system (RAAS) blockades on renal outcomes in COVID-19 patients. However, the association between RAAS blockade use and incident AKI in COVID-19 patients has not been fully understood. We investigated the association between RAAS blockade exposure and COVID-19-related AKI in hospitalized patients through meta-analysis. Electronic databases were searched up to 24th December 2020. Summary estimates of pooled odds ratio (OR) of COVID-19-related AKI depending on RAAS blockade exposure were obtained through random-effects model. The random-effect meta-analysis on fourteen studies (17,876 patients) showed that RAAS blockade use was significantly associated with increased risk of incident AKI in hospitalized COVID-19 patients (OR 1.68; 95% confidence interval 1.19-2.36). Additional analysis showed that the association of RAAS blockade use on COVID-19-related AKI remains significant even after stratification by drug class and AKI severity. RAAS blockade use is significantly associated with the incident AKI in hospitalized COVID-19 patients. Therefore, careful monitoring of renal complications is recommended for COVID-19 patients with recent RAAS blockade use due to the potential risk of AKI.

CD3+CD4-CD8- Double-negative αß T cells attenuate lung ischemia-reperfusion injury.

OBJECTIVE: Lung ischemia-reperfusion injury (IRI) is a common complication after lung transplantation, and immune cells have been implicated in modulating outcomes. We hypothesized that a newly described subset of αß T-cell receptor positive cells; that is, CD4-CD8- (double negative [DN]) T cells, are found in lungs and can protect against lung IRI. METHODS: Ischemia was induced in C57BL/6 mice by left pulmonary artery and vein occlusion for 30 minutes followed by 180 minutes of reperfusion. These mice were paired with sham hilar dissected surgical controls. In mice undergoing IRI, adoptive transfer of DN T cells or conventional T cells was performed 12 hours before occlusion. Flow cytometry was used to quantify T cells and inflammatory cytokines, and apoptotic signaling pathways were evaluated with immunoblotting. Lung injury was assessed with Evans blue dye extravasation. RESULTS: DN T cells were significantly higher (5.29% ± 1% vs 2.21% ± 3%; P < .01) in IRI lungs and secreted higher levels of interleukin-10 (30% ± 5% vs 6% ± 1%; P < .01) compared with surgical sham controls. Immunoblotting, hematoxylin and eosin staining and Evans blue dye demonstrated that adoptive transfer of DN T cells significantly decreased interstitial edema (P < .01) and attenuated apoptosis/cleaved caspase-3 expression in the lungs following lung IRI (P < .01). CONCLUSIONS: DN T cells traffic into lungs during IRI, and have tissue protective functions regulating inflammation and apoptosis. We propose a potential novel immunoregulatory function of DN T cells during lung IRI.

A spurious elevation of serum creatinine level in a patient with Crohn's disease without histologic kidney damage: a case report and review of the literature / Elevação espúria do nível de creatinina sérica em ­paciente com doença de Crohn sem lesão renal histológica: relato de caso e revisão da literatura

ABSTRACT Patients with inflammatory bowel disease (IBD) are prone to develop kidney injury. Renal involvement in IBD patients is usually diagnosed by the measurement of serum creatinine and the estimation of the glomerular filtration rate. We describe a patient with IBD who presented with large fluctuations in his serum creatinine level (~3.0-fold) without significant histologic abnormalities and with a normal cystatin C level. This appears to be related to a high-protein diet and intermittent fasting. Even though the impact of a high-protein diet on mild elevations of the serum creatinine level has been described, large fluctuations in serum creatinine from diet alone, as seen in this case, have never been reported, raising the question about the potential contribution of inflamed bowel on gut absorption or metabolism of creatinine. This case highlights the importance of a detailed history, including the dietary habits, when encountering a patient with increased serum creatinine level, and careful interpretation of serum creatinine in a patient with a creatinine high-protein diet or underlying IBD.

RESUMO Pacientes com doença inflamatória intestinal (DII) são propensos a desenvolver lesão renal. O envolvimento renal em pacientes com DII é geralmente diagnosticado pela medição da creatinina sérica e pela estimativa da taxa de filtração glomerular. Descrevemos um paciente com DII que apresentou grandes flutuações em seu nível de creatinina sérica (~3,0 vezes) sem anormalidades histológicas significativas e com nível normal de cistatina C. Isso parece estar relacionado a uma dieta rica em proteínas e jejum intermitente. Ainda que o impacto de uma dieta rica em proteínas em elevações leves do nível de creatinina sérica tenha sido descrito, nunca foram relatadas grandes flutuações na creatinina sérica apenas devido à dieta, como observado neste caso, o que levanta a questão sobre a possível contribuição do intestino inflamado na absorção intestinal ou no metabolismo da creatinina. Esse caso destaca a importância de um histórico detalhado, incluindo os hábitos alimentares, ao se deparar com um paciente com nível de creatinina sérica aumentado, e a interpretação cuidadosa da creatinina sérica em um paciente com dieta rica em proteínas ou DII subjacente.

Characterization of kidney CD45intCD11bintF4/80+MHCII+CX3CR1+Ly6C- "intermediate mononuclear phagocytic cells".

Kidney immune cells play important roles in pathogenesis of many diseases, including ischemia-reperfusion injury (IRI) and transplant rejection. While studying murine kidney T cells, we serendipitously identified a kidney mononuclear phagocytic cell (MPC) subset characterized by intermediate surface expression of CD45 and CD11b. These CD45intCD11bint MPCs were further identified as F4/80+MHCII+CX3CR1+Ly6C- cells, comprising ~17% of total CD45+ cells in normal mouse kidney (P < 0.01) and virtually absent from all other organs examined except the heart. Systemic clodronate treatment had more significant depletive effect on the CD45intCD11bint population (77.3%±5.9%, P = 0.03) than on CD45highCD11b+ population (14.8%±16.6%, P = 0.49). In addition, CD45intCD11bint MPCs had higher phagocytic function in the normal kidney (35.6%±3.3% vs. 24.1%±2.2%, P = 0.04), but lower phagocytic capacity in post-ischemic kidney (54.9%±1.0% vs. 67.8%±1.9%, P < 0.01) compared to the CD45highCD11b+ population. Moreover, the CD45intCD11bint population had higher intracellular production of the pro-inflammatory tumor necrosis factor (TNF)-α (58.4%±5.2% vs. 27.3%±0.9%, P < 0.001) after lipopolysaccharide (LPS) stimulation and lower production of the anti-inflammatory interleukin (IL)-10 (7.2%±1.3% vs. 14.9%±2.2%, P = 0.02) following kidney IRI, suggesting a functional role under inflammatory conditions. The CD45intCD11bint cells increased early after IRI, and then abruptly decreased 48h later, whereas CD45highCD11b+ cells steadily increased after IRI before declining at 72h (P = 0.03). We also identified the CD45intCD11bint MPC subtype in human kidney. We conclude that CD45intCD11bint F4/80+MHCII+CX3CR1+Ly6C-population represent a unique subset of MPCs found in both mouse and human kidneys. Future studies will further characterize their role in kidney health and disease.