Activation of renal profibrotic TGFβ controlled signaling cascades by calcineurin and mTOR inhibitors

Peritoneal transformation shortly after kidney transplantation in pediatric patients with preceding chronic peritoneal dialysis

BACKGROUND

The unphysiological composition of peritoneal dialysis (PD) fluids induces progressive peritoneal fibrosis, hypervascularization and vasculopathy. Information on these alterations after kidney transplantation (KTx) is scant.

METHODS

Parietal peritoneal tissues were obtained from 81 pediatric patients with chronic kidney disease stage 5 (CKD5), 72 children on PD with low glucose degradation product (GDP) PD fluids, and from 20 children 4-8 weeks after KTx and preceding low-GDP PD. Tissues were analyzed by digital histomorphometry and quantitative immunohistochemistry.

RESULTS

While chronic PD was associated with peritoneal hypervascularization, after KTx vascularization was comparable to CKD5 level. Submesothelial CD45 counts were 40% lower compared with PD, and in multivariable analyses independently associated with microvessel density. In contrast, peritoneal mesothelial denudation, submesothelial thickness and fibrin abundance, number of activated, submesothelial fibroblasts and of mesothelial-mesenchymal transitioned cells were similar after KTx. Diffuse peritoneal podoplanin positivity was present in 40% of the transplanted patients. In subgroups matched for age, PD vintage, dialytic glucose exposure and peritonitis incidence, submesothelial hypoxia-inducible factor 1-alpha abundance and angiopoietin 1/2 ratio were lower after KTx, reflecting vessel maturation, while arteriolar and microvessel p16 and cleaved Casp3 were higher. Submesothelial mast cell count and interleukin-6 were lower, whereas transforming growth factor-beta induced pSMAD2/3 was similar as compared with children on PD.

CONCLUSIONS

Peritoneal membrane damage induced with chronic administration of low-GDP PD fluids was less severe after KTx. While peritoneal microvessel density, primarily defining PD transport and ultrafiltration capacity, was normal after KTx and peritoneal inflammation less pronounced, diffuse podoplanin positivity and profibrotic activity were prevalent.

Managing immunosuppressive therapy in potentially cured post-kidney transplant cancer (excluding non-melanoma skin cancer): overview of the available evidence and guidance for shared decision making

Kidney transplant recipients (KTRs) have increased incidence of de novo cancers. After having undergone treatment for cancer with curative intent, reducing the overall immunosuppressive load and/or switching to an alternative drug regimen may potentially be of great benefit to avoid cancer recurrence, but should be balanced against the risks of rejection and/or severe adverse events. The TLJ (Transplant Learning Journey) project is an initiative from the European Society for Organ Transplantation (ESOT). This article reports a systematic literature search undertaken by TLJ Workstream 3 to answer the questions: (1) Should we decrease the overall anti‐rejection therapy in potentially cured post‐kidney transplant cancer (excluding non‐melanoma skin cancer)? (2) Should we switch to mammalian target of rapamycin inhibitors (mTORi) in potentially cured post‐kidney transplant cancer (excluding non‐melanoma skin cancer)? The literature search revealed insufficient solid data on which to base recommendations, so this review additionally presents an extensive overview of the indirect evidence on the benefits versus risks of alterations in immunosuppressive medication. We hope this summary will help transplant physicians advise KTRs on how best to continue with anti‐rejection therapy after receiving cancer treatment with curative intent, and aid shared decision‐making, ensuring that patient preferences are taken into account.

Hydrogen-rich water alleviates cyclosporine A-induced nephrotoxicity via the Keap1/Nrf2 signaling pathway

Oxidative stress induced by long-term cyclosporine A (CsA) administration is a major cause of chronic nephrotoxicity, which is characterized by tubular atrophy, tubular cell apoptosis, and interstitial fibrosis in the progression of organ transplantation. Although hydrogen-rich water (HRW) has been used to prevent various oxidative stress-related diseases, its underlying mechanisms remain unclear. This study investigated the effects of HRW on CsA-induced nephrotoxicity and its potential mechanisms. After administration of CsA (25 mg/kg/day), rats were treated with or without HRW (12 mL/kg) for 4 weeks. Renal function and vascular activity were investigated. Histological changes in kidney tissues were analyzed using Masson's trichrome and terminal deoxynucleotidyl transferase dUTP nick-end labeling stains. Oxidative stress markers and the activation of the Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway were also measured. We found that CsA increased the levels of reactive oxygen species (ROS) and malonaldehyde (MDA), but it reduced glutathione (GSH) and superoxide dismutase (SOD) levels. Such alterations induced vascular dysfunction, tubular atrophy, interstitial fibrosis, and tubular apoptosis. This was evident secondary to an increase in urinary protein, serum creatinine, and blood urea nitrogen, ultimately leading to renal dysfunction. Conversely, HRW decreased levels of ROS and MDA while increasing the activity of GSH and SOD. This was accompanied by an improvement in vascular and renal function. Moreover, HRW significantly decreased the level of Keap1 and increased the expression of Nrf2, NADPH dehydrogenase quinone 1, and heme oxygenase 1. In conclusion, HRW restored the balance of redox status, suppressed oxidative stress damage, and improved kidney function induced by CsA via activation of the Keap1/Nrf2 signaling pathway.

Decreased Expression of Urinary Mammalian Target of Rapamycin mRNA Is Related to Chronic Renal Fibrosis in IgAN

Background

Renal fibrosis is a common outcome of all pathological types of chronic kidney disease (CKD). However, the noninvasive detection of renal fibrosis remains a challenge.

Methods

We collected urine samples from 154 biopsy-proven IgA nephropathy (IgAN) patients and 61 healthy controls. The expression of mTOR was measured and the correlation with renal function parameter and pathological indicators. The receiver operating characteristic (ROC) curve for the diagnosis of IgAN and renal fibrosis was calculated.

Results

The urinary mammalian target of rapamycin (mTOR) expression was decreased in IgAN patients. The expression of mTOR was correlated with serum creatinine, blood urea nitrogen, estimated glomerular filtration rate, 24 h proteinuria, and cystatin C. Further, the urinary mTOR expression was significantly decreased in severe renal fibrosis patients compared with mild or moderate renal fibrosis patients. Urinary mTOR expression was correlated with score of tubulointerstitial fibrosis (TIF) and score of glomerular sclerosis. The ROC curve showed that mTOR can diagnose IgAN at a cut-off value of 0.930 with the sensitivity of 90.2% and specificity of 73.8% and renal fibrosis at a cut-off value of 0.301 with the sensitivity of 71.7% and specificity of 64.8%.

Conclusion

Urinary mTOR mRNA expression was a potential biomarker for diagnosis of IgAN and renal fibrosis in IgAN patients.

Fetal Toxicity of Immunosuppressive Drugs in Pregnancy

Women affected by autoimmune diseases, organ transplantation, or neoplasia need to continue immunosuppressive treatment during pregnancy. In this setting, not only a careful planning of pregnancy, but also the choice of drugs is critical to preventing maternal complications and minimizing the fetal risks. Some immunosuppressive drugs are teratogenic and should be replaced even before the pregnancy, while other drugs need to be managed with caution to prevent fetal risks, including miscarriage, intrauterine growth restriction, prematurity, and low birth weight. In particular, the increasing use of biologic agents raises the question of their compatibility with reproduction. In this review we present data on the indication and safety in pregnancy of the most frequently used immunosuppressive drugs.

TRP channels in cardiac and intestinal fibrosis

It is now widely accepted that advanced fibrosis underlies many chronic inflammatory disorders and is the main cause of morbidity and mortality of the modern world. The pathogenic mechanism of advanced fibrosis involves diverse and intricate interplays between numerous extracellular and intracellular signaling molecules, among which the non-trivial roles of a stress-responsive Ca²⁺/Na⁺-permeable cation channel superfamily, the transient receptor potential (TRP) protein, are receiving growing attention. Available evidence suggests that several TRP channels such as TRPC3, TRPC6, TRPV1, TRPV3, TRPV4, TRPA1, TRPM6 and TRPM7 may play central roles in the progression and/or prevention of fibroproliferative disorders in vital visceral organs such as lung, heart, liver, kidney, and bowel as well as brain, blood vessels and skin, and may contribute to both acute and chronic inflammatory processes involved therein. This short paper overviews the current knowledge accumulated in this rapidly growing field, with particular focus on cardiac and intestinal fibrosis, which are tightly associated with the pathogenesis of atrial fibrillation and inflammatory bowel diseases such as Crohn's disease.