Postoperative cellular stress in the kidney is associated with an early systemic γδ T-cell immune cell response

Leptospirosis: A dual threat - predisposing risk for renal transplant and trigger for renal transplant dysfunction

Leptospirosis (LTPS) is a bacterial infection that affects humans, often with mild or no symptoms. It is estimated that approximately 10 % of patients with LTPS may experience multi-organ dysfunction, including renal abnormalities. In regions where LTPS is widespread, a considerable number of instances involving acute kidney injury (AKI) and chronic kidney disease (CKD) of unknown etiology (CKDu) have been reported. Additionally, studies have shown a correlation between kidney graft dysfunction in patients with stable kidney transplants after LTPS. These findings indicate that exposure to LTPS may increase the likelihood of kidney transplantation due to the onset of both acute and chronic kidney injuries. Simultaneously, it poses a potential risk to the stability of kidney grafts. Unfortunately, there is limited scientific literature addressing this issue, making it difficult to determine the negative impact that LTPS may have, such as its role as a risk factor for the need of kidney transplantation or as a threat to individuals who have undergone kidney transplants. This study aims to shed light on the immune mechanisms triggered during LTPS infection and their importance in both kidney damage and allograft dysfunction.

Lymphocytes and innate immune cells in acute kidney injury and repair

Acute kidney injury (AKI) is a common and serious disease entity that affects native kidneys and allografts but for which no specific treatments exist. Complex intrarenal inflammatory processes driven by lymphocytes and innate immune cells have key roles in the development and progression of AKI. Many studies have focused on prevention of early injury in AKI. However, most patients with AKI present after injury is already established. Increasing research is therefore focusing on mechanisms of renal repair following AKI and prevention of progression from AKI to chronic kidney disease. CD4+ and CD8+ T cells, B cells and neutrophils are probably involved in the development and progression of AKI, whereas regulatory T cells, double-negative T cells and type 2 innate lymphoid cells have protective roles. Several immune cells, such as macrophages and natural killer T cells, can have both deleterious and protective effects, depending on their subtype and/or the stage of AKI. The immune system not only participates in injury and repair processes during AKI but also has a role in mediating AKI-induced distant organ dysfunction. Targeted manipulation of immune cells is a promising therapeutic strategy to improve AKI outcomes.

Effects of therapeutic hypercapnia on the expression and function of γδT cells in transplanted lungs in rats

OBJECTIVE

To investigate the effect of therapeutic hypercapnia on the expression and function of gamma delta T (γδ T) cells during ischemia-reperfusion injury (IRI) after lung transplantation.

METHODS

We randomly divided male Wistar rats into three groups (n = 6 in each group), the control group (group N), the IRI group (group I), and the therapeutic hypercapnia group (group H). We then assessed pulmonary edema, neutrophil infiltration, wet-to-dry (W/D) weight ratio, and microscopic histopathology and separately measured the levels of γδT cell surface antigen (TCR) and Interleukin-17 (IL-17) using flow cytometry and enzyme-linked immunosorbent assays (ELISAs).

RESULTS

The infiltration of neutrophils and the expression of TCR and IL-17 were significantly increased in the I group compared to the control, and the biopsy edema in group I was more severe. Arterial partial pressure of oxygen (PaO2) was decreased after reperfusion in group I compared with the control group. W/D weight ratio, neutrophil infiltration, and the expression of TCR and IL-17 decreased drastically in the H group compared to the I group.

CONCLUSION

Our findings suggest that γδ T lymphocytes were directly involved in lung injury. In addition, therapeutic hypercapnia effectively reduced the expression of γδ T cells and IL-17, and this has the potential to become a treatment strategy for IRI and an intervention to improve lung function.

Advances in the study of B cells in renal ischemia-reperfusion injury

Renal ischemia-reperfusion injury (IRI) is a non-negligible clinical challenge for clinicians in surgeries such as renal transplantation. Functional loss of renal tubular epithelial cell (TEC) in IRI leads to the development of acute kidney injury, delayed graft function (DGF), and allograft rejection. The available evidence indicates that cellular oxidative stress, cell death, microvascular dysfunction, and immune response play an important role in the pathogenesis of IRI. A variety of immune cells, including macrophages and T cells, are actively involved in the progression of IRI in the immune response. The role of B cells in IRI has been relatively less studied, but there is a growing body of evidence for the involvement of B cells, which involve in the development of IRI through innate immune responses, adaptive immune responses, and negative immune regulation. Therefore, therapies targeting B cells may be a potential direction to mitigate IRI. In this review, we summarize the current state of research on the role of B cells in IRI, explore the potential effects of different B cell subsets in the pathogenesis of IRI, and discuss possible targets of B cells for therapeutic aim in renal IRI.

Targeting HMGB1: A Potential Therapeutic Strategy for Chronic Kidney Disease

High-mobility group protein box 1 (HMGB1) is a member of a highly conserved high-mobility group protein present in all cell types. HMGB1 plays multiple roles both inside and outside the cell, depending on its subcellular localization, context, and post-translational modifications. HMGB1 is also associated with the progression of various diseases. Particularly, HMGB1 plays a critical role in CKD progression and prognosis. HMGB1 participates in multiple key events in CKD progression by activating downstream signals, including renal inflammation, the onset of persistent fibrosis, renal aging, AKI-to-CKD transition, and important cardiovascular complications. More importantly, HMGB1 plays a distinct role in the chronic pathophysiology of kidney disease, which differs from that in acute lesions. This review describes the regulatory role of HMGB1 in renal homeostasis and summarizes how HMGB1 affects CKD progression and prognosis. Finally, some promising therapeutic strategies for the targeted inhibition of HMGB1 in improving CKD are summarized. Although the application of HMGB1 as a therapeutic target in CKD faces some challenges, a more in-depth understanding of the intracellular and extracellular regulatory mechanisms of HMGB1 that underly the occurrence and progression of CKD might render HMGB1 an attractive therapeutic target for CKD.

Role of T cells in ischemic acute kidney injury and repair

Ischemic acute kidney injury (AKI) is a common medical problem with significant mortality and morbidity, affecting a large number of patients globally. Ischemic AKI is associated with intrarenal inflammation as well as systemic inflammation; thus, the innate and adaptive immune systems are implicated in the pathogenesis of ischemic AKI. Among various intrarenal immune cells, T cells play major roles in the injury process and in the repair mechanism affecting AKI to chronic kidney disease transition. Importantly, T cells also participate in distant organ crosstalk during AKI, which affects the overall outcomes. Therefore, targeting T cell-mediated pathways and T cell-based therapies have therapeutic promise for ischemic AKI. Here, we review the major populations of kidney T cells and their roles in ischemic AKI.

Unconventional T cells and kidney disease

Unconventional T cells are a diverse and underappreciated group of relatively rare lymphocytes that are distinct from conventional CD4⁺ and CD8⁺ T cells, and that mainly recognize antigens in the absence of classical restriction through the major histocompatibility complex (MHC). These non-MHC-restricted T cells include mucosal-associated invariant T (MAIT) cells, natural killer T (NKT) cells, γδ T cells and other, often poorly defined, subsets. Depending on the physiological context, unconventional T cells may assume either protective or pathogenic roles in a range of inflammatory and autoimmune responses in the kidney. Accordingly, experimental models and clinical studies have revealed that certain unconventional T cells are potential therapeutic targets, as well as prognostic and diagnostic biomarkers. The responsiveness of human Vγ9Vδ2 T cells and MAIT cells to many microbial pathogens, for example, has implications for early diagnosis, risk stratification and targeted treatment of peritoneal dialysis-related peritonitis. The expansion of non-Vγ9Vδ2 γδ T cells during cytomegalovirus infection and their contribution to viral clearance suggest that these cells can be harnessed for immune monitoring and adoptive immunotherapy in kidney transplant recipients. In addition, populations of NKT, MAIT or γδ T cells are involved in the immunopathology of IgA nephropathy and in models of glomerulonephritis, ischaemia-reperfusion injury and kidney transplantation.

Lymphocytes: Versatile Participants in Acute Kidney Injury and Progression to Chronic Kidney Disease

Background: Acute kidney injury (AKI) remains a major global public health concern due to its high morbidity and mortality. The progression from AKI to chronic kidney disease (CKD) makes it a scientific problem to be solved. However, it is with lack of effective treatments. Summary: Both innate and adaptive immune systems participate in the inflammatory process during AKI, and excessive or dysregulated immune responses play a pathogenic role in renal fibrosis, which is an important hallmark of CKD. Studies on the pathogenesis of AKI and CKD have clarified that renal injury induces the production of various chemokines by renal parenchyma cells or resident immune cells, which recruits multiple-subtype lymphocytes in circulation. Some infiltrated lymphocytes exacerbate injury by proinflammatory cytokine production, cytotoxicity, and interaction with renal resident cells, which constructs the inflammatory environment and induces further injury, even death of renal parenchyma cells. Others promote tissue repair by producing protective cytokines. In this review, we outline the diversity of these lymphocytes and their mechanisms to regulate the whole pathogenic stages of AKI and CKD; discuss the chronological responses and the plasticity of lymphocytes related to AKI and CKD progression; and introduce the potential therapies targeting lymphocytes of AKI and CKD, including the interventions of chemokines, cytokines, and lymphocyte frequency regulation in vivo, adaptive transfer of ex-expanded lymphocytes, and the treatments of gut microbiota or metabolite regulations based on gut-kidney axis. Key Message: In the process of AKI and CKD, T helper (Th) cells, innate, and innate-like lymphocytes exert mainly pathogenic roles, while double-negative T (DNT) cells and regulatory T cells (Tregs) are confirmed to be protective. Understanding the mechanisms by which lymphocytes mediate renal injury and renal fibrosis is necessary to promote the development of specific therapeutic strategies to protect from AKI and prevent the progression of CKD.

Pattern of Tumor-Infiltrating Lymphocytes in Mixed Epithelial and Stromal Tumor of the Kidney: A Review of Five Cases

Mixed epithelial and stromal tumor of the kidney (MESTK), a benign rare tumor with malignant transformation potential, is thought to be derived from fetal or immature cells originating from the mesonephric and Müllerian ducts. However, due to its rarity, little is known about the anti-tumor immune responses in MESTK. Herein, we present five cases of MESTK and evaluate the population of tumor-infiltrating lymphocytes (TILs) using a freshly obtained MESTK sample. Microscopically, TILs were scattered or clustered in large aggregates in the stroma in all five cases; furthermore, three cases exhibited heavy, large lymphocytic aggregates with no well-organized tertiary lymphoid structures with germinal centers. Flow cytometric analysis of TILs in one freshly obtained MESTK sample revealed that >40% of CD3⁺ T cells were effector memory Fas⁺CD28⁻ γδ T cells expressing high levels of programmed cell death protein 1 and inducible T-cell co-stimulator, but low levels of CD44 and CD27. Most αß T cells exhibited a naïve phenotype. Additionally, we detected many activated class-switched CD21⁺CD27⁺ B cells as well as CD11c^highIgM^high marginal zone B-like and CD27⁻CD21⁻CD23⁻ immunoglobulin (Ig)D^highIgM^low age-associated B-like cells. Collectively, for the first time, we report the immune microenvironment pattern of MESTK to oncogenic stress.

Steatotic Livers Are More Susceptible to Ischemia Reperfusion Damage after Transplantation and Show Increased γδ T Cell Infiltration

Liver transplantation (LTx) is often the only possible therapy for many end-stage liver diseases, but successful long-term transplant outcomes are limited by multiple factors, including ischemia reperfusion injury (IRI). This situation is aggravated by a shortage of transplantable organs, thus encouraging the use of inferior quality organs. Here, we have investigated early hepatic IRI in a retrospective, exploratory, monocentric case-control study considering organ marginality. We analyzed standard LTx biopsies from 46 patients taken at the end of cold organ preparation and two hours after reperfusion, and we showed that early IRI was present after two hours in 63% of cases. Looking at our data in general, in accordance with Eurotransplant criteria, a marginal transplant was allocated at our institution in about 54% of cases. We found that patients with a marginal-organ LTx showing evidence of IRI had a significantly worse one-year survival rate (51% vs. 75%). As we saw in our study cohort, the marginality of these livers was almost entirely due to steatosis. In contrast, survival rates in patients receiving a non-marginal transplant were not influenced by the presence or absence of IRI. Poorer outcomes in marginal organs prompted us to examine pre- and post-reperfusion biopsies, and it was revealed that transplants with IRI demonstrated significantly greater T cell infiltration. Molecular analyses showed that higher mRNA expression levels of CXCL-1, CD3 and TCRγ locus genes were found in IRI livers. We therefore conclude that the marginality of an organ, namely steatosis, exacerbates early IRI by enhancing effector immune cell infiltration. Preemptive strategies targeting immune pathways could increase the safety of using marginal organs for LTx.

Modeling of the immune response in the pathogenesis of solid tumors and its prognostic significance

BACKGROUND

Tumor initiation and subsequent progression are usually long-term processes, spread over time and conditioned by diverse aspects. Many cancers develop on the basis of chronic inflammation; however, despite dozens of years of research, little is known about the factors triggering neoplastic transformation under these conditions. Molecular characterization of both pathogenetic states, i.e., similarities and differences between chronic inflammation and cancer, is also poorly defined. The secretory activity of tumor cells may change the immunophenotype of immune cells and modify the extracellular microenvironment, which allows the bypass of host defense mechanisms and seems to have diagnostic and prognostic value. The phenomenon of immunosuppression is also present during chronic inflammation, and the development of cancer, due to its duration, predisposes patients to the promotion of chronic inflammation. The aim of our work was to discuss the above issues based on the latest scientific insights. A theoretical mechanism of cancer immunosuppression is also proposed.

CONCLUSIONS

Development of solid tumors may occur both during acute and chronic phases of inflammation. Differences in the regulation of immune responses between precancerous states and the cancers resulting from them emphasize the importance of immunosuppressive factors in oncogenesis. Cancer cells may, through their secretory activity and extracellular transport mechanisms, enhance deterioration of the immune system which, in turn, may have prognostic implications.

T Cells and Acute Kidney Injury: A Two-Way Relationship

Acute Kidney Injury (AKI) complicates up to 10% of hospital admissions substantially increasing patient morbidity and mortality. Experimental evidence supports that AKI initiation and maintenance results from immune-mediated damage. Exogenous injury sources directly damage renal cells which produce pro-inflammatory mediators recruiting immune cells and furthering kidney injury. Many AKI studies focus on activation of innate immunity; major components include complement pathways, neutrophils, and monocytes. Recently, growing evidence emphasizes T lymphocytes role in affecting AKI pathogenesis and magnitude. In particular, T helper 17 lymphocytes enhance tissue injury by recruiting neutrophils and other inflammatory cells, while regulatory T cells conversely reduce renal injury and facilitate repair. Intriguingly, evidence supports local parenchymal-T cell interactions as essential to producing T cell phenotypic changes affecting long-term kidney and patient survival. Herein, we review T cells effects on AKI and patient outcomes and discuss related new therapeutic approaches to improve outcomes of affected individuals.

Urinary [TIMP-2] × [IGFBP7] and serum procalcitonin to predict and assess the risk for short-term outcomes in septic and non-septic critically ill patients

BACKGROUND

Biomarkers can play a critical role by facilitating diagnosis and stratification of disease, as well as assessment or prediction of disease severity. Urinary tissue inhibitor of metalloproteinase-2 and insulin-like growth factor binding protein 7 product ([TIMP-2] × [IGFBP7]) predict the development and progression of AKI and recently procalcitonin (PCT), a widely used biomarker for sepsis diagnosis and management, has been associated with AKI occurrence in ICU patients. To assess combinations of [TIMP-2] × [IGFBP7] and PCT results for prediction and risk stratification of short-term outcomes in septic and non-septic patients, a retrospective cohort analysis of critically ill patients was performed in a multidisciplinary ICU. ROC curve analysis was used in order to evaluate predictive performance of combined results of [TIMP-2] × [IGFBP7] and PCT at the time of admission for AKI development. To verify the utility of adding [TIMP-2] × [IGFBP7] and PCT results for risk assessment, we evaluated the predictive value of having a single-marker positivity compared to a double-marker positivity using the widely used cut-off of 0.3 (ng/mL)²/1000 for [TIMP-2] × [IGFBP7] and 0.5 μg/L for PCT. Risk assessment for AKI occurrence within 48 h, acute kidney disease (AKD) and mortality at 7 days was performed by logistic/Cox regression analysis.

RESULTS

433 patients were analysed, of whom 168 had AKI within 48 h (93 septic and 65 non-septic patients). Combination of [TIMP-2] × [IGFBP7] and PCT showed a good predictive ability for AKI occurrence (AUC 0.81, 95% CI 0.77-0.86, p < 0.001, Sens 78%, Spec 73%). Combinations of biomarkers increased the odd ratios (OR) considerably. A single-marker positivity showed a fourfold risk increase, while the double-marker positivity a 26-fold risk increase for AKI occurrence. Moreover, the double-marker positivity showed an elevated risk for AKD at 7 days in non-septic patients (OR 15.9, 95% CI 3,21-73,57, p < 0.001) and for mortality within 7 days in septic patients (HR 4.1, 95% CI 1.4-11.8, p = 0.001).

CONCLUSIONS

Although combining the results of [TIMP-2] × [IGFBP7] and PCT may be a useful tool to identify and stratify ICU patients at high risk for septic AKI and short-term adverse outcomes, data should be confirmed in a large prospective study.

T Lymphocytes in Acute Kidney Injury and Repair

Innate and adaptive immune systems participate in the pathogenesis of acute kidney injury (AKI). Considerable data from different research teams have shown the importance of T lymphocytes in the pathophysiology of AKI and, more recently, prevention and repair. T cells can generate or resolve inflammation by secreting specific cytokines and growth factors as well as interact with other immune and stromal cells to induce kidney injury or promote tissue repair. There also are emerging data on the role of T cells in the progression of AKI to chronic kidney disease and organ cross-talk in AKI. These data set the stage for immunomodulatory therapies for AKI. This review focuses on the major populations of T lymphocytes and their roles as mediators for AKI and repair.