Risk predictors in patients with diabetic nephropathy

Inflammation and Kidney Injury in Diabetic African American Men

African Americans are disproportionately burdened by diabetic kidney disease (DKD). However, little is known about the cellular and molecular mechanisms underlying the onset and progression of DKD in this population. The goal of the current study was to determine the association between specific inflammation markers and kidney injury in diabetic African American men. To this end, we recruited diabetic patients either with (n = 20) or without (n = 87) diagnosed kidney disease along with age-matched nondiabetic controls (n = 81). Urinary albumin-to-creatinine ratios (UACRs) and estimated glomerular filtration rates (eGFR) were used for biochemical assessment of kidney function. We then measured plasma and urinary levels of seven inflammatory markers, including adiponectin, C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), TNF receptor 1 (TNFR1), TNF receptor 2 (TNFR2), interleukin-6 (IL-6), and intercellular cell adhesion molecule-1 (ICAM-1). Plasma levels of TNF-α, TNFR1, and TNFR2 were significantly higher in diabetics with macroalbuminuria compared to nondiabetic controls and diabetics with normoalbuminuria or microalbuminuria. Likewise, urinary levels of ICAM-1 were higher in diabetics with macroalbuminuria compared to the other groups. Indeed, urinary ICAM-1, plasma TNF-α, and adiponectin had moderate positive correlations with UACR while plasma TNFR1 and TNFR2 levels were strongly correlated with kidney injury, indicated by multiple biomarkers of kidney injury. In contrast, though plasma CRP was elevated in diabetic subjects relative to nondiabetic controls, its levels did not correlate with kidney injury. Together, these data suggest that inflammation, particularly that mediated by the TNF-α/NF-κB signaling axis, may play a role in the pathogenesis of DKD in African American men.

Meprin Metalloprotease Deficiency Associated with Higher Mortality Rates and More Severe Diabetic Kidney Injury in Mice with STZ-Induced Type 1 Diabetes

Meprins are membrane-bound and secreted metalloproteinases consisting of α and/or β subunits that are highly expressed in kidney epithelial cells and are differentially expressed in podocytes and leukocytes (macrophages and monocytes). Several studies have implicated meprins in the progression of diabetic nephropathy (DN) and fibrosis-associated kidney disease. However, the mechanisms by which meprins modulate DN are not understood. To delineate the role of meprins in DN, we subjected meprin αβ knockout (αβKO) mice and their wild-type (WT) counterparts to streptozotocin-induced type 1 diabetes. The 18-week survival rates were significantly lower for diabetic meprin αβKO mice when compared to those for their WT counterparts. There were significant decreases in mRNA and protein levels for both meprin α and β in diabetic WT kidneys. Furthermore, the blood urea nitrogen levels and urine albumin/creatinine ratios increased in diabetic meprin αβKO but not in diabetic WT mice, indicating that meprins may be protective against diabetic kidney injury. The brush border membrane levels of villin, a meprin target, significantly decreased in diabetic WT but not in diabetic meprin αβKO kidneys. In contrast, isoform-specific increases in cytosolic levels of the catalytic subunit of PKA, another meprin target, were demonstrated for both WT and meprin αβKO kidneys.

Investigation of the induction of antibodies against Crandell-Rees feline kidney cell lysates and feline renal cell lysates after parenteral administration of vaccines against feline viral rhinotracheitis, calicivirus, and panleukopenia in cats

OBJECTIVE

To determine whether administration of Crandell-Rees feline kidney (CRFK) cell lysates or vaccines against feline viral rhinotracheitis, calicivirus, and panleukopenia (FVRCP vaccines) that likely contain CRFK cell proteins induces antibodies against CRFK cell or feline renal cell (FRC) lysates in cats.

ANIMALS

14 eight-week-old cats.

PROCEDURE

Before and after the study, renal biopsy specimens were obtained from each cat for histologic evaluation. Each of 4 FVRCP vaccines was administered to 2 cats at weeks 0, 3, 6, and 50. Between weeks 0 and 50, another 3 pairs of cats received 11 CRFK cell lysate inoculations SC (10, 50, or 50 microg mixed with alum). Clinicopathologic evaluations and ELISAs to detect serum antibodies against CRFK cell or FRC lysates were performed at intervals.

RESULTS

Cats had no antibodies against CRFK cell or FRC lysates initially. All cats administered CRFK cell lysate had detectable antibodies against CRFK cell or FRC lysates on multiple occasions. Of 6 cats vaccinated parenterally, 5 had detectable antibodies against CRFK cell lysate at least once, but all 6 had detectable antibodies against FRC lysate on multiple occasions. Cats administered an intranasal-intraocular vaccine did not develop detectable antibodies against either lysate. Important clinicopathologic or histologic abnormalities were not detected during the study.

CONCLUSIONS AND CLINICAL RELEVANCE

Parenteral administration of vaccines containing viruses likely grown on CRFK cells induced antibodies against CRFK cell and FRC lysates in cats. Hypersensitization with CRFK cell proteins did not result in renal disease in cats during the 56-week study.