Impact of nocturnal hypoxia on glycaemic control, appetite, gut microbiota and inflammation in adults with type 2 diabetes mellitus: A single-blind cross-over trial.

High altitude residents have a lower incidence of type 2 diabetes mellitus (T2DM). Therefore, we examined the effect of repeated overnight normobaric hypoxic exposure on glycaemic control, appetite, gut microbiota and inflammation in adults with T2DM. Thirteen adults with T2DM [glycated haemoglobin (HbA1c): 61.1 ± 14.1 mmol mol-1; aged 64.2 ± 9.4 years; four female] completed a single-blind, randomised, sham-controlled, cross-over study for 10 nights, sleeping when exposed to hypoxia (fractional inspired O2 [ F I O 2 ${{F}_{{\mathrm{I}}{{{\mathrm{O}}}_{\mathrm{2}}}}}$ ] = 0.155; ∼2500 m simulated altitude) or normoxic conditions ( F I O 2 ${{F}_{{\mathrm{I}}{{{\mathrm{O}}}_{\mathrm{2}}}}}$  = 0.209) in a randomised order. Outcome measures included: fasted plasma [glucose]; [hypoxia inducible factor-1α]; [interleukin-6]; [tumour necrosis factor-α]; [interleukin-10]; [heat shock protein 70]; [butyric acid]; peak plasma [glucose] and insulin sensitivity following a 2 h oral glucose tolerance test; body composition; appetite indices ([leptin], [acyl ghrelin], [peptide YY], [glucagon-like peptide-1]); and gut microbiota diversity and abundance [16S rRNA amplicon sequencing]. During intervention periods, accelerometers measured physical activity, sleep duration and efficiency, whereas continuous glucose monitors were used to assess estimated HbA1c and glucose management indicator and time in target range. Overnight hypoxia was not associated with changes in any outcome measure (P > 0.05 with small effect sizes) except fasting insulin sensitivity and gut microbiota alpha diversity, which exhibited trends (P = 0.10; P = 0.08 respectively) for a medium beneficial effect (d = 0.49; d = 0.59 respectively). Ten nights of overnight moderate hypoxic exposure did not significantly affect glycaemic control, gut microbiome, appetite, or inflammation in adults with T2DM. However, the intervention was well tolerated and a medium effect-size for improved insulin sensitivity and reduced alpha diversity warrants further investigation. KEY POINTS: Living at altitude lowers the incidence of type 2 diabetes mellitus (T2DM). Animal studies suggest that exposure to hypoxia may lead to weight loss and suppressed appetite. In a single-blind, randomised sham-controlled, cross-over trial, we assessed the effects of 10 nights of hypoxia (fractional inspired O2 ∼0.155) on glucose homeostasis, appetite, gut microbiota, inflammatory stress ([interleukin-6]; [tumour necrosis factor-α]; [interleukin-10]) and hypoxic stress ([hypoxia inducible factor 1α]; heat shock protein 70]) in 13 adults with T2DM. Appetite and inflammatory markers were unchanged following hypoxic exposure, but an increased insulin sensitivity and reduced gut microbiota alpha diversity were associated with a medium effect-size and statistical trends, which warrant further investigation using a definitive large randomised controlled trial. Hypoxic exposure may represent a viable therapeutic intervention in people with T2DM and particularly those unable or unwilling to exercise because barriers to uptake and adherence may be lower than for other lifestyle interventions (e.g. diet and exercise).

Donor human leukocyte antigen specific antibodies predict development and define prognosis in transplant glomerulopathy.

The pathogenesis of transplant glomerulopathy (TG) remains unclear, with evidence of human leukocyte antigen (HLA) antibodies as important contributors to the disease. We studied the risk factors and the associations of HLA antibodies in the development of TG. Sixty-one cases with morphologic features of TG were identified and compared with contemporaneous matched patients (without TG) from a 17-year period, all undergoing renal biopsy in a single center. Univariate risk factors for TG were previous glomerulitis [odds ratio (OR) 3.3, 95% confidence interval (95% CI) [1.2-9.4], p = 0.025), delayed graft function (OR 2.3 [1.0-5.1], p = 0.042), HLA class I presensitization defined by Luminex solid-phase immunoassays (OR 5.0 [2.3-11.0]. p < 0.001), and de novo posttransplant development of donor HLA specific antibody (DSA) (OR 4.7 [1.7-13.2], p = 0.002). Only DSA remained significantly associated with TG after adjustment (OR 3.8 [1.1-12.9], p = 0.032). DSA was detected in >50% of TG patients, suggesting HLA antibodies play a critical role in TG pathogenesis. TG patients with DSA had increased risk of graft loss (median graft survival 4.4-5.2 years), whereas patients with morphologic features of TG without DSA had similar graft survival compared with the non-TG group (median graft survival 15 years). Thus, DSA is a useful predictor for graft failure in TG patients.

Effect of interleukin-2 receptor antibody therapy on acute rejection risk and severity, long-term renal function, infection and malignancy-related mortality in renal transplant recipients.

In renal transplantation, the use of interleukin-2 receptor antibody (IL-2Ra) has been associated with reduced rejection rates, but the effect of this agent on rejection severity and type, long-term graft function and risk of infection and malignancy-related mortality remains unclear. Using Australia and New Zealand Dialysis and Transplant Registry, all live- and deceased-donor renal transplant recipients in Australia between 2000 and 2006 were included. Of the 3344 renal transplant recipients, 1874 (56.0%) received no induction and 1470 (44.0%) had received IL-2Ra. Compared with no induction, IL-2Ra was associated with reduced rejection risk (relative risk 0.70, 95% CI 0.60, 0.81) and higher estimated glomerular filtration rate at 5 years (difference in means 3.51, 95% CI 0.83, 6.19). Severity and type of rejection were similar in both the groups. The adjusted rate of death attributed to malignancy for no induction and IL-2Ra per 1000 patient-years was 1.48 and 1.63, respectively, whereas death attributed to infection was 2.42 and 2.16 respectively. This registry analysis demonstrates that IL-2Ra induction in kidney transplantation is associated with substantial clinical benefits of reduced risk of acute rejection and improved long-term graft function without an increase in adverse events.

Reduction in cardiovascular death after kidney transplantation.

BACKGROUND: Cardiovascular (CVS) disease is the commonest cause of death after kidney transplantation. In the general population, CVS mortality has reduced significantly over the last two decades; however, this trend has not been specifically examined in the kidney transplant population. METHODS: We studied all patients in Australia and New Zealand with a functioning kidney transplant between 1980 and 2007 and examined trends in the cause and timing of all 2195 deaths recorded after kidney transplantation in the Australia and New Zealand Dialysis and Transplant registry. Poisson regression was used to compare death rates over the time periods. RESULTS: CVS events were the commonest cause of death throughout all the time points examined; however, CVS death rates significantly decreased with an adjusted risk ratio of 0.61 (95% confidence interval, 0.38-0.96; P=0.034) for 2005 to 2007 era. In comparison, death rates due to malignancy have increased significantly over this period. Decreased CVS death rates have occurred despite increasing comorbidity at the time of transplantation. Factors associated with CVS death were older recipient age, preexisting CVS disease, and diabetes mellitus. There was a significantly lower CVS death rate in patients with a glomerular filtration rate >48 mL/min compared with those with poor renal function (risk ratio, 0.66; 95% confidence interval, 0.45-0.95; P=0.024). CONCLUSIONS: These trends suggest improvements in CVS risk management and outcomes in the kidney transplant population in Australia and New Zealand.