Sex Differences in Biopsy-Confirmed Diabetic Kidney Disease

Risk of End-Stage Renal Disease in Patients With Systemic Lupus Erythematosus and Diabetes Mellitus: A Danish Nationwide Cohort Study

OBJECTIVE

The risk of end-stage renal disease (ESRD) is increased in patients with systemic lupus erythematosus (SLE). This study was undertaken to determine whether diabetes mellitus (DM) increases ESRD risk in a large inception cohort of SLE patients.

METHODS

By means of the Danish National Patient Registry, we identified 3,178 adult patients diagnosed as having SLE between January 1, 1996, and July 31, 2018. DM was defined as the date of first hospital contact for DM or date of a first prescription of an antidiabetic drug. ESRD was defined as first registration of dialysis, renal transplant, or terminal renal insufficiency in the Danish National Patient Registry. ESRD incidence was compared between SLE patients with DM (SLE-DM) and those without DM (SLE-non-DM). Hazard ratios (HRs), adjusted for sex, age, educational level, and occupational status at baseline were calculated for sex, age, educational level, and hypertension (at baseline or during follow-up) strata. The overall hazard ratio (HR) was also adjusted for hypertension.

RESULTS

The SLE-DM group included 290 patients, of whom 77% were female, compared with 85% of the 2,859 patients in the SLE-non-DM group. SLE-DM patients had a 3 times higher risk of ESRD compared with SLE-non-DM patients (multivariable-adjusted HR 3.3 [95% confidence interval 1.8-6.1]). In stratified multivariable-adjusted analyses, DM increased the rate of ESRD in women and men, patients ≥50 years old at baseline, those with low educational level at baseline, and those with concomitant hypertension.

CONCLUSION

Our findings indicate that SLE patients with DM have a markedly higher risk of developing ESRD compared with SLE patients without DM.

Increased Renal Medullary NOX-4 in Female but Not Male Mice during the Early Phase of Type 1 Diabetes: Potential Role of ROS in Upregulation of TGF-β1 and Fibronectin in Collecting Duct Cells

Chronic diabetes mellitus (DM) can lead to kidney damage associated with increased reactive oxygen species (ROS), proteinuria, and tubular damage. Altered protein expression levels of transforming growth factor-beta 1 (TGF-β1), fibronectin, and renal NADPH oxidase (NOX-4) are associated with the profibrotic phenotype in renal tubular cells. NOX-4 is one of the primary sources of ROS in the diabetic kidney and responsible for the induction of profibrotic factors in collecting duct (CD) cells. The renal medulla is predominantly composed of CDs; in DM, these CD cells are exposed to high glucose (HG) load. Currently there is no published literature describing the expression of these markers in the renal medulla in male and female mice during the early phase of DM, or the role of NOX-4-induced ROS. Our aim was to evaluate changes in transcripts and protein abundances of TGF-β1, fibronectin, and NOX-4 along with ROS levels in renal medullary tissues from male and female mice during a short period of streptozotocin (STZ)-induced type 1 DM and the effect of HG in cultured CD cells. CF-1 mice were injected with or without a single dose of STZ (200 mg/kg) and euthanized at day 6. STZ females showed higher expression of fibronectin and TGF-β1 when compared to control mice of either gender. Interestingly, STZ female mice showed a >30-fold increase on mRNA levels and a 3-fold increase in protein levels of kidney medullary NOX-4. Both male and female STZ mice showed increased intrarenal ROS. In primary cultures of inner medullary CD cells exposed to HG over 48 h, the expression of TGF-β1, fibronectin, and NOX-4 were augmented. M-1 CD cells exposed to HG showed increased ROS, fibronectin, and TGF-β1; this effect was prevented by NOX-4 inhibition. Our data suggest that at as early as 6 days of STZ-induced DM, the expression of profibrotic markers TGF-β1 and fibronectin increases in renal medullary CD cells. Antioxidants mechanisms in male and female in renal medullary tissues seems to be differentially regulated by the actions of NOX-4.