Estimating Vitamin D threshold for the Indian population: Delving into the actual disease burden.

Background: Based on the current guidelines in practice, a vast majority of the healthy Indian population is vitamin D deficient. Since the serum 25 hydroxycholecalciferol (25HCC) levels are affected by race and skin pigmentation, the normal range of vitamin D may differ in the Indians compared to the Western population. This study attempted to determine a population-specific threshold for 25 HCC levels associated with adequate bone health and calcium and phosphate homeostasis in healthy Indians. Methods: Subjects aged 20-50 years were included in the study. The exclusion criteria were obesity, chronic renal disease, liver failure, diabetes mellitus, thyroid disorders, a recent history of fracture, constant joint pain, and postmenopausal status. In addition, participants on prescribed medication such as glucocorticoids, anticonvulsants, or antifungals, as well as vitamin D and calcium supplementation, were also excluded.Blood samples were analyzed for serum calcium, phosphate, alkaline phosphatase, 25HCC, 1,25dihydroxycholecalciferol, parathyroid hormone (PTH), procollagen type-I N propeptide, and C-terminal telopeptide of type 1 collagen.Locally estimated smoothing scatter plot (LOESS) curves and Spearman correlation were utilized to study the correlation of all the biochemical parameters with 25 HCC to achieve thresholds. Results: The study consisted of 270 healthy participants, out of which 97.8% were found to have vitamin D levels below 30 ng/ml. In addition, 8.8% had raised PTH, and 1.85% had hypocalcemia. Furthermore, 1.48% had raised serum alkaline phosphatase and hypophosphatemia, respectively. A weak inverse correlation was seen between 25 HCC and PTH (rs = -0.437, p < 0.001), as well as alkaline phosphatase (rs = -0.1475, p = 0.015), while a weak positive correlation was seen with serum phosphate (rs = 0.128, p = 0.047). Conclusion: For a healthy Indian population, the reference range of 25 HCC is much lower, and the lower limit of normal is approximately 13.5 ng/ml. This study indicates that vitamin D insufficiency in this population starts at 25 HCC values of 13.5 ng/ml and deficiency at 7 ng/ml.

Recovery after Critical Illness and Acute Kidney Injury.

AKI is a common complication in hospitalized and critically ill patients. Its incidence has steadily increased over the past decade. Whether transient or prolonged, AKI is an independent risk factor associated with poor short- and long-term outcomes, even if patients do not require KRT. Most patients with early AKI improve with conservative management; however, some will require dialysis for a few days, a few weeks, or even months. Approximately 10%-30% of AKI survivors may still need dialysis after hospital discharge. These patients have a higher associated risk of death, rehospitalization, recurrent AKI, and CKD, and a lower quality of life. Survivors of critical illness may also suffer from cognitive dysfunction, muscle weakness, prolonged ventilator dependence, malnutrition, infections, chronic pain, and poor wound healing. Collaboration and communication among nephrologists, primary care physicians, rehabilitation providers, physical therapists, nutritionists, nurses, pharmacists, and other members of the health care team are essential to create a holistic and patient-centric care plan for overall recovery. Integration of the patient and family members in health care decisions, and ongoing education throughout the process, are vital to improve patient well-being. From the nephrologist standpoint, assessing and promoting recovery of kidney function, and providing appropriate short- and long-term follow-up, are crucial to prevent rehospitalizations and to reduce complications. Return to baseline functional status is the ultimate goal for most patients, and dialysis independence is an important part of that goal. In this review, we seek to highlight the varying aspects and stages of recovery from AKI complicating critical illness, and propose viable strategies to promote recovery of kidney function and dialysis independence. We also emphasize the need for ongoing research and multidisciplinary collaboration to improve outcomes in this vulnerable population.

Zinc Inhibits HIF-Prolyl Hydroxylase Inhibitor-Aggravated VSMC Calcification Induced by High Phosphate.

Vascular calcification is a life-threatening clinical condition in chronic kidney disease (CKD) and is associated with reduced zinc serum levels. Anemia is another frequent complication of CKD. Hypoxia-inducible factor (HIF) stabilizers, also known as HIF prolyl hydroxylase inhibitors (PHI), are promising candidates to treat CKD-associated anemia by increasing erythropoietin synthesis. Recent evidence suggests that HIFs play a pivotal role in vascular calcification. Our study explored feasible impacts of HIF PHI on phosphate (Pi)-induced calcification of vascular smooth muscle cells (VSMCs) and tested whether zinc might inhibit this mineralization process. Treatment of VSMCs with PHI aggravated Pi-induced calcium deposition and Pi uptake. PHI promoted Pi-induced loss of smooth muscle cell markers (ACTA-2, MYH11, SM22α) and enhanced osteochondrogenic gene expression (Msx-2, BMP-2, Sp7) triggering osteochondrogenic phenotypic switch of VSMCs. These effects of PHI paralleled with increased pyruvate dehydrogenase kinase 4 (PDK4) expression, decreased Runx2 Ser451 phosphorylation, and reduced cell viability. Zinc inhibited Pi-induced mineralization of VSMCs in a dose-dependent manner and also attenuated the pro-calcification effect of PHI in Pi-induced mineralization. Zinc inhibited osteochondrogenic phenotypic switch of VSMCs reflected by lowering Pi uptake, decreasing the expressions of Msx-2, BMP-2, and Sp7 as well as the loss of smooth muscle cell-specific markers. Zinc preserved phosphorylation state of Runx2 Ser451, decreased PDK4 level, and restored cell viability. PHI alone reduced the expression of smooth muscle markers without inducing mineralization, which was also inhibited by zinc. In addition, we observed a significantly lower serum zinc level in CKD as well as in patients undergoing carotid endarterectomy compared to healthy individuals. Conclusion - PHI promoted the loss of smooth muscle markers and augmented Pi-induced osteochondrogenic phenotypic switch leading to VSMCs calcification. This mineralization process was attenuated by zinc. Enhanced vascular calcification is a potential risk factor during PHI therapy in CKD which necessitates the strict follow up of vascular calcification and zinc supplementation.

Heme oxygenase-1 mitigates ferroptosis in renal proximal tubule cells.

Ferroptosis is an iron-dependent form of regulated nonapoptotic cell death, which contributes to damage in models of acute kidney injury (AKI). Heme oxygenase-1 (HO-1) is a cytoprotective enzyme induced in response to cellular stress, and is protective against AKI because of its antiapoptotic and anti-inflammatory properties. However, the role of HO-1 in regulating ferroptosis is unclear. The purpose of this study was to elucidate the role of HO-1 in regulating ferroptotic cell death in renal proximal tubule cells (PTCs). Immortalized PTCs obtained from HO-1+/+ and HO-1-/- mice were treated with erastin or RSL3, ferroptosis inducers, in the presence or absence of antioxidants, an iron source, or an iron chelator. Cells were assessed for changes in morphology and metabolic activity as an indicator of cell viability. Treatment of HO-1+/+ PTCs with erastin resulted in a time- and dose-dependent increase in HO-1 gene expression and protein levels compared with vehicle-treated controls. HO-1-/- cells showed increased dose-dependent erastin- or RSL3-induced cell death in comparison to HO-1+/+ PTCs. Iron supplementation with ferric ammonium citrate in erastin-treated cells decreased cell viability further in HO-1-/- PTCs compared with HO-1+/+ cells. Cotreatment with ferrostatin-1 (ferroptosis inhibitor), deferoxamine (iron chelator), or N-acetyl-l-cysteine (glutathione replenisher) significantly increased cell viability and attenuated erastin-induced ferroptosis in both HO-1+/+ and HO-1-/- PTCs. These results demonstrate an important antiferroptotic role of HO-1 in renal epithelial cells.

Intravenous bilirubin provides incomplete protection against renal ischemia-reperfusion injury in vivo.

Exogenous bilirubin (BR) substitutes for the protective effects of heme oxygenase (HO) in several organ systems. Our objective was to investigate the effects of exogenous BR in an in vivo model of ischemia-reperfusion injury (IRI) in the rat kidney. Four groups of male Sprague-Dawley rats were anesthetized using isoflurane in oxygen and treated with 1) 5 mg/kg intravenous (iv) BR, 1 h before ischemia and 6-h reperfusion; 2) vehicle 1 h before ischemia and 6-h reperfusion; 3) 20 mg/kg iv BR, 1 h before and during ischemia; and 4) vehicle 1 h before and during ischemia. Bilateral renal clamping (30 min) was followed by 6-h reperfusion. Infusion of 5 mg/kg iv BR achieved target levels in the serum at 6 h postischemia (31 +/- 9 micromol/l). Infusion of 20 mg/kg BR reached 50 +/- 22 micromol/l at the end of ischemia, and a significant improvement was seen in serum creatinine at 6 h (1.07 +/- 28 vs. 1.38 +/- 0.18 mg/dl, P = 0.043). Glomerular filtration rate, estimated renal plasma flow, fractional excretion of electrolytes, and renal vascular resistance were not significantly improved in BR-treated groups. Histological grading demonstrated a trend toward preservation of cortical proximal tubules in rats receiving 20 mg/kg iv BR compared with control; however, neither BR dose provided protection against injury to the renal medulla. At the doses administered, iv BR did not provide complete protection against IRI in vivo. Combined supplementation of both BR and carbon monoxide may be required to preserve renal blood flow and adequately substitute for the protective effects of HO in vivo.

Potent anti-tumor effects of an active site mutant of human manganese-superoxide dismutase. Evolutionary conservation of product inhibition.

Mn-SOD serves as the primary cellular defense against oxidative damage by converting superoxide radicals (O(2)(-)) to O(2) and H(2)O(2). A unique characteristic of this mitochondrial anti-oxidant enzyme is the conservation from bacteria to man of a rapidly formed product inhibited state. Using site-directed mutagenesis, we have generated an active site mutant (H30N) of human Mn-SOD, which exhibits significantly reduced product inhibition and increased enzymatic efficiency. Overexpression of the H30N enzyme causes anti-proliferative effects in vitro and anti-tumor effects in vivo. Our results provide a teleological basis for the phylogenetically invariant nature of position His-30 and the evolutionary conservation of product inhibition. These data also provide more direct intracellular evidence for the signaling role associated with H(2)O(2).

Adeno-associated virus-mediated IL-10 gene therapy inhibits diabetes recurrence in syngeneic islet cell transplantation of NOD mice.

Islet transplantation represents a potential cure for type 1 diabetes, yet persistent autoimmune and allogeneic immunities currently limit its clinical efficacy. For alleviating the autoimmune destruction of transplanted islets, newly diagnosed NOD mice were provided a single intramuscular injection of recombinant adeno-associated viral vector encoding murine IL-10 (rAAV-IL-10) 4 weeks before renal capsule delivery of 650 syngeneic islets. A dose-dependent protection of islet grafts was observed. Sixty percent (3 of 5) of NOD mice that received a transduction of a high-dose (4 x 10(9) infectious units) rAAV-IL-10 remained normoglycemic for at least 117 days, whereas diabetes recurred within 17 days in mice that received a low-dose rAAV-IL-10 (4 x 10(8) infectious units; 5 of 5) as well as in all of the control mice (5 of 5 untreated and 4 of 4 rAAV-green fluorescent protein-transduced). Serum IL-10 levels positively correlated with prolonged graft survival and were negatively associated with the intensity of autoimmunity. The mechanism of rAAV-IL-10 protection involved a reduction of lymphocytic infiltration as well as induction of antioxidant enzymes manganese superoxide dismutase and heme oxygenase 1 in islet grafts. These studies support the utility of immunoregulatory cytokine gene therapy delivered by rAAV for preventing autoimmune disease recurrence in transplant-based therapies for type 1 diabetes.