ovalbumin and Diabetic-Nephropathies

The kidney tubulointerstitium has been reported to be protected from T-cell--mediated damage by sequestration from the T-cell compartment. We examined the ability of autoreactive T cells to infiltrate the kidney in a transgenic mouse model.. RIP-mOVA transgenic mice express the model autoantigen, membrane-bound ovalbumin (mOVA), in kidney proximal tubular cells and pancreatic beta cells. OVA-specific CD8(+) T cells (OT-I cells) were transferred into these recipient mice and their immune response against pancreas and kidney tissue was compared.. When OVA-specific CD8(+) T cells (OT-I cells) were injected into RIP-mOVA mice, they were activated in the renal and pancreatic lymph nodes by cross-presentation. These in vivo-activated OT-I cells caused the destruction of pancreatic islets leading to autoimmune diabetes, but did not infiltrate the kidney. Neither CD95--CD95 ligand interactions, which have been proposed to induce apoptosis in T cells infiltrating immunologically privileged sites, nor CD30 signaling was responsible for the lack of kidney infiltration. When OT-I cells were activated in vitro prior to injection, they could infiltrate the kidney and caused acute renal failure when injected in high numbers.. A mechanism distinct from previously described organ-specific protective mechanisms such as sequestration of antigen or CD95-mediated immunoprivilege contributes to the protection of the kidney tubulointerstitium from infiltration by autoreactive CD8(+) T cell.

Topics: Animals; Basement Membrane; CD8-Positive T-Lymphocytes; Diabetic Nephropathies; fas Receptor; Glycosuria; Homeodomain Proteins; Kidney Tubules, Proximal; Mice; Mice, Knockout; Nephritis, Interstitial; Ovalbumin; Receptors, Antigen, T-Cell; Signal Transduction

Endogenous advanced glycation endproducts (AGEs) include chemically crosslinking species (glycotoxins) that contribute to the vascular and renal complications of diabetes mellitus (DM). Renal excretion of the catabolic products of endogenous AGEs is impaired in patients with diabetic or nondiabetic kidney disease (KD). The aim of this study was to examine the oral absorption and renal clearance kinetics of food AGEs in DM with KD and whether circulating diet-derived AGEs contain active glycotoxins. Thirty-eight diabetics (DM) with or without KD and five healthy subjects (NL) received a single meal of egg white (56 g protein), cooked with (AGE-diet) or without fructose (100 g) (CL-diet). Serum and urine samples, collected for 48 hr, were monitored for AGE immunoreactivity by ELISA and for AGE-specific crosslinking reactivity, based on complex formation with 125I-labeled fibronectin. The AGE-diet, but not the CL-diet, produced distinct elevations in serum AGE levels in direct proportion to amount ingested (r = 0.8, P < 0.05): the area under the curve for serum ( approximately 10% of ingested AGE) correlated directly with severity of KD; renal excretion of dietary AGE, although normally incomplete (only approximately 30% of amount absorbed), in DM it correlated inversely with degree of albuminuria, and directly with creatinine clearance (r = 0.8, P < 0.05), reduced to <5% in DM with renal failure. Post-AGE-meal serum exhibited increased AGE-crosslinking activity (two times above baseline serum AGE, three times above negative control), which was inhibited by aminoguanidine. In conclusion, (i) the renal excretion of orally absorbed AGEs is markedly suppressed in diabetic nephropathy patients, (ii) daily influx of dietary AGEs includes glycotoxins that may constitute an added chronic risk for renal-vascular injury in DM, and (iii) dietary restriction of AGE food intake may greatly reduce the burden of AGEs in diabetic patients and possibly improve prognosis.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Albuminuria; Creatinine; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Diet, Diabetic; Female; Food Analysis; Fructose; Glycation End Products, Advanced; Humans; Intestinal Absorption; Male; Middle Aged; Ovalbumin; Reference Values; Risk Factors