Silvia Mercuri

Background: Ischemia/reperfusion injury (IRI) is considered one of the major risk factors involved in the development of delayed graft function that significantly impacts both the early and long-term function of allografts due to its harmful effects on cells. Purpose: This narrative review aims to explore the emerging aspects of IRI in organ transplantation, focusing on the still unclear relationships between IRI and the development of both T-cell-mediated and/or antibody-mediated rejections. Key findings: Recently, efforts aimed at increasing the knowledge of the mechanisms involved have revealed that IRI is connected to rejection processes through a complex of interconnected pathways. These pathways affect both the viability and the metabolism of immune cells, ultimately influencing graft outcomes. Therefore, these pathways demonstrate the complexity of immune responses after transplantation and play a role in both acute and chronic rejection processes. Conclusions: Improving graft outcomes requires an understanding of the multifaceted relationship between IRI and immune-mediated rejection, which is critical to improve graft outcomes. Further research is needed to clarify these mechanisms and develop targeted strategies to mitigate IRI and its impact on transplant rejection.

C3 glomerulopathy (C3G) is the predominant cause of complement-mediated membranoproliferative glomerulonephritis and is considered a rare disorder caused by genetic or acquired dysregulation of the alternative complement pathway. There are no established treatment guidelines for treating kidney-transplanted recipients with C3G recurrence, as they are already on immunosuppressive protocols. Furthermore, non-complement-specific immunosuppressive drugs appear to offer limited benefits for patients with C3G in native kidneys. Therefore, modulating the complement system appears to be the most effective strategy for this specific patient population. We describe the use of Iptacopan in a 38-year-old kidney-transplanted patient with C3G recurrence. Iptacopan was associated with a significant and striking improvement in the patient’s clinical and laboratories status. A follow-up kidney biopsy performed 5 months after the initiation of Iptacopan revealed a reduction in endocapillary, extracapillary and mesangial hypercellularity, along with a decreased extent of parietal proteinaceous deposits observed on light microscopy. The direct control of the complement dysregulation underlying the pathogenesis of C3G with Iptacopan was accompanied by improvements in clinical, laboratory and histological features, with demonstrated reduced disease activity and slowed disease progression. Therefore, the case report described is intended to shed light on the potential role of new AP complement blockers in the treatment of C3G.

Background: Anderson–Fabry disease (AFD) is a rare genetic disorder characterized by a deficiency of α-galactosidase A activity and the accumulation of glycosphingolipids in tissues, which leads to multiorgan damage. Cardiovascular magnetic resonance (CMR) and the T1 mapping technique are essential tools for the assessment of AFD cardiac involvement. Moreover, the T1 mapping technique has proved to be a successful non-invasive method for the early detection of patients most at risk for kidney disease. We evaluated the application of MRI in patients with AFD to assess renal involvement. Methods: We conducted a retrospective analysis of 19 patients (Group A) with histologically proven AFD who underwent routine CMR examinations for the evaluation of cardiac involvement, selecting specific sequences that also showed the left kidney, compared to a control population (Group B, 19 patients) without kidney disease. A Spearman’s rank-order correlation was run to assess the relationship between the T1 mapping values of the heart and kidney in Group A and between the kidneys of Groups A and B. Results: There was a positive correlation between the heart and kidney T1 values in Group A (rho = 0.32). More interestingly, we observed a negative correlation between the kidney values of both groups (Group A mean 1284 ± 137 ms, Group B mean 1073 ± 57 ms, rho = −0.38), which is probably related to the presence of microvascular damage and infiltrates in the kidneys of AFD patients. Conclusions: To our knowledge, these results are the first to highlight the key value of T1 mapping in assessing pathological changes and aiding in the non-invasive diagnosis of renal involvement in AFD.

The aging process contributes significantly to the onset of chronic diseases, which are the primary causes of global mortality, morbidity, and healthcare costs. Numerous studies have shown that the removal of senescent cells from tissues extends lifespan and reduces the occurrence of age-related diseases. Consequently, there is growing momentum in the development of drugs targeting these cells. Among them, mTOR and SGLT-2 inhibitors have garnered attention due to their diverse effects: mTOR inhibitors regulate cellular growth, metabolism, and immune responses, while SGLT-2 inhibitors regulate glucose reabsorption in the kidneys, resulting in various beneficial metabolic effects. Importantly, these drugs may act synergistically by influencing senescence processes and pathways. Although direct studies on the combined effects of mTOR inhibition and SGLT-2 inhibition on age-related processes are limited, this review aims to highlight the potential synergistic benefits of these drugs in targeting senescence.

Dendritic cells (DCs) are a heterogeneous group of antigen-presenting cells crucial for fostering allograft tolerance while simultaneously supporting host defense against infections and cancer. Within the tumor microenvironment, DCs can either mount an immune response against cancer cells or foster immunotolerance, presenting a dual role. In immunocompromised individuals, posttransplant malignancies pose a significant health concern, with DCs serving as vital players in immune responses against cancer cells. Both recipient- and donor-derived DCs play a critical role in the rejection process, infiltrating the transplanted organ and sustaining T-cell responses. The use of immunosuppressive drugs represents the predominant approach to control this immunological barrier in transplanted organs. Evidence has shed light on the immunopharmacology of these drugs and novel strategies for manipulating DCs to promote allograft survival. Therefore, comprehending the mechanisms underlying this intricate microenvironment and the effects of immunosuppressive therapy on DCs is crucial for developing targeted therapies to reduce graft failure rates. This review will delve into the fundamental immunobiology of DCs and provide a detailed exploration of their clinical significance concerning alloimmune responses and posttransplant malignancies.

The paracrine signaling pathways for the crosstalk between pericytes and endothelial cells are essential for the coordination of cell responses to challenges such as hypoxia in both healthy individuals and pathological conditions. Ischemia–reperfusion injury (IRI), one of the causes of cellular dysfunction and death, is associated with increased expression of genes involved in cellular adaptation to a hypoxic environment. Hypoxic inducible factors (HIFs) have a central role in the response to processes initiated by IRI not only linked to erythropoietin production but also because of their participation in inflammation, angiogenesis, metabolic adaptation, and fibrosis. While pericytes have an essential physiological function in erythropoietin production, a lesser-known role of HIF stabilization during IRI is that pericytes’ HIF expression could influence vascular remodeling, cell loss and organ fibrosis. Better knowledge of mechanisms that control functions and consequences of HIF stabilization in pericytes beyond erythropoietin production is advisable for the development of therapeutic strategies to influence disease progression and improve treatments. Thus, in this review, we discuss the dual roles—for good or bad—of HIF stabilization during IRI, focusing on pericytes, and consequences in particular for the kidneys.

Hypoxia activates hypoxia-related signaling pathways controlled by hypoxia-inducible factors (HIFs). HIFs represent a quick and effective detection system involved in the cellular response to insufficient oxygen concentration. Activation of HIF signaling pathways is involved in improving the oxygen supply, promoting cell survival through anaerobic ATP generation, and adapting energy metabolism to meet cell demands. Hypoxia can also contribute to the development of the aging process, leading to aging-related degenerative diseases; among these, the aging of the immune system under hypoxic conditions can play a role in many different immune-mediated diseases. Thus, in this review we aim to discuss the role of HIF signaling pathways following cellular hypoxia and their effects on the mechanisms driving immune system senescence.