Escher, G. | bioRxiv Science

bioRxiv2021

Nephrotoxicity of Calcineurin Inhibitors in kidney epithelial cells is independent of Calcineurin and NFAT signaling.

BackgroundCalcineurin inhibitors (CNI) such as Cyclosporine A (CsA) and Tacrolimus (FK506) are commonly used after renal transplantation in order to suppress the immune system. In lymphoid cells, CsA acts via the Calcineurin-NFAT axis, whereas in non-lymphoid cells, such as kidney epithelial cells, CsA induces Calcineurin inhibitor toxicity (CNT). Up to date, it is unknown via which off-targets CsA induces CNT in kidney epithelial cells. MethodsIn vitro experiments using a surrogate marker to measure CNT induction as well as in vivo studies with acute CNT, were used in order to elucidate the underlying molecular mechanism. ResultsInhibition of the NFAT axis does not show any nephrotoxicity. However, inhibition of p38 and PI3K/Akt Kinases showed induction of nephrotoxicity. ConclusionsThese findings show that CsA acts NFAT independent on kidney epithelial cells. Moreover, inhibition of certain protein kinases mimic CsA activity on kidney epithelial cells indicating that p38 and PI3K/Akt kinase pathways might be involved in CNT progression on kidney epithelial cells.

pharmacology and toxicology↗

bioRxiv2019

Associations of ‘Relative corticosterone deficiency’ with genetic variation in CYP17A1 and metabolic syndrome features

Context and objectiveCommon genetic variants in CYP17A1 associate with higher blood pressure, putatively from impaired 17-hydroxylase activity and mineralocorticoid excess. However, the same variants protect against obesity and insulin resistance. We tested whether CYP17A1 variants that enhance 17-hydroxylase activity cause relative corticosterone deficiency. Since corticosterone is thought to contribute disproportionately to negative feedback in the hypothalamic-pituitary-adrenal axis, we also tested whether lower corticosterone associates with higher cortisol and hence with metabolic syndrome.\n\nDesignCross-sectional studies within the population-based Orkney Complex Disease Study (ORCADES; n=2018), VIKING Health Study Shetland (VIKING; n=2098), East Hertfordshire study (EHERTS; n=279), Edinburgh Type 2 Diabetes Study (ET2DS; n=903), and the Swiss Kidney Project on Genes in Hypertension (SKIPOGH; n=888).\n\nOutcome measuresCortisol and corticosterone in morning plasma samples in ORCADES, VIKING and ET2DS, and in EHERTS in plasma following overnight dexamethasone suppression (0.25mg) and 30 mins after ACTH1-24 (1{micro}g); cortisol and corticosterone metabolites in day and night urine samples in SKIPOGH. Features of the metabolic syndrome including body mass index, systolic blood pressure, lipid profile, fasting glucose, fasting insulin and HOMA-IR.\n\nResultsIn ORCADES, ET2DS and SKIPOGH, CYP17A1 variants were associated with corticosterone:cortisol ratio. In ORCADES, VIKING and ET2DS there were consistent associations of morning plasma cortisol and corticosterone with BMI, blood pressure, lipid profile, fasting glucose and HOMA-IR. In EHERTS, however, after dexamethasone suppression and ACTH1-24 stimulation, impaired glucose tolerance and insulin sensitivity were associated with higher cortisol but lower corticosterone. Similarly, in SKIPOGH, low corticosterone:cortisol metabolite ratios were associated with high BMI and dyslipidemia.\n\nConclusions Relative corticosterone deficiency, due to a primary alteration in adrenal steroidogenesis favouring cortisol over corticosterone, may mediate the associations of genetic variation in CYP17A1 with metabolic syndrome. However, additional determinants of variation in plasma corticosterone are likely to explain its generally positive associations with features of metabolic syndrome.

epidemiology↗