Accelerated senescence in kidneys of low-birth-weight rats after catch-up growth.

Epidemiological studies show a strong association between low birth weight and hypertension, renal, and cardiovascular disease, especially after catch-up growth. Senescence is an important contributor to the progression of chronic disease. Developmentally programmed premature senescence may be a link among low birth weight, catch-up growth, and adult disease. Low birth weight was induced by feeding pregnant rats a low-protein diet from day 12 of gestation to 10 days postdelivery. Low- and normal-birth-weight male offspring were weaned onto regular or high-calorie diets to enhance catch-up growth. Kidneys and hearts of offspring were analyzed for RNA and protein markers of stress-induced senescence (p16, p21, p53, Rb). Markers of mitochondrial stress (p66Shc) and activation of endoplasmic reticulum protein secretion (Ero1alpha) were analyzed as regulators of reactive oxygen species generation. Reactive oxygen species are known to be associated with premature aging. Senescence markers were not different in low- or normal-birth-weight kidneys at birth. During rapid catch-up growth, p16 and p21 increased significantly in low-birth-weight kidneys and hearts (P < 0.01). Renal p16 levels increased progressively and were significantly higher in low-birth-weight kidneys at 3 and 6 mo (P < or = 0.02). Renal p66Shc and Ero1alpha were significantly higher in low- compared with normal- birth-weight kidneys at 6 mo, suggesting reactive oxygen species generation (P < or = 0.03). Low-birth-weight rats exhibit accelerated senescence in kidneys and hearts after rapid catch-up growth, a likely important link between early growth and subsequent hypertension, renal, and cardiovascular disease.

Oncostatin M pathway plays a major role in the renal acute phase response.

The acute phase response is traditionally characterized by hepatic synthesis of proteins as an inflammatory response to injury, with interleukin-6 (IL-6) being the key mediator. In contrast, microarray studies in human renal transplant implantation biopsies indicate a strong acute phase response in the deceased donor kidney, associated with a significant upregulation of oncostatin M receptor beta (OSMR). The aim of this study was to determine whether the kidney can generate a strong acute phase response, mediated by the OSM/OSMR gateway. Genes associated with the IL-6 cytokine family and acute phase reactants were analyzed by real-time RT-PCR in four groups of human biopsies spanning a spectrum of renal injury. OSM, OSMR, and fibrinogen beta (FGB) were progressively more highly expressed from prenephrectomy, living donor, deceased donor, to discarded donor kidneys, suggesting correlation with severity of injury and local renal synthesis. Acute phase response gene expression was analyzed in human proximal tubular cells in culture in response to OSM. OSM induced a significant increase in expression of FGB, OSMR, serpin peptidase inhibitor A1, IL-6, and lipopolysaccharide binding protein, and a decrease in IL-6R. These changes were largely attenuated by coincubation with an OSMR blocking antibody, indicating the OSM effect was mediated through OSMR. OSM also resulted in a significantly altered expression of acute phase genes compared with IL-6 or leukemia inhibitory factor, suggesting that OSM is the predominant cytokine mediating the renal tubular acute phase response. In conclusion, the renal parenchyma is capable of generating a strong acute phase response, likely mediated via OSM/OSMR.