Hematopoietic growth factor inducible neurokinin-1 (Gpnmb/Osteoactivin) is a biomarker of progressive renal injury across species.

We sought to find a urinary biomarker for chronic kidney disease and tested hematopoietic growth factor inducible neurokinin-1 (HGFIN, also known as Gpnmb/Osteoactivin) as it was found to be a kidney injury biomarker in microarray studies. Here, we studied whether HGFIN is a marker of kidney disease progression. Its increase in kidney disease was confirmed by real-time PCR after 5/6 nephrectomy, in streptozotocin-induced diabetes, and in patients with chronic kidney disease. In the remnant kidney, HGFIN mRNA increased over time reflecting lesion chronicity. HGFIN was identified in the infarct portion of the remnant kidney in infiltrating hematopoietic interstitial cells, and in distal nephron tubules of the viable remnant kidney expressed de novo with increasing time. In vitro, it localized to cytoplasmic vesicles and cell membranes. Epithelial cells lining distal tubules and sloughed luminal tubule cells of patients expressed HGFIN protein. The urine HGFIN-to-creatinine ratio increased over time after 5/6 nephrectomy; increased in patients with proteinuric and polycystic kidney disease; and remained detectable in urine after prolonged freezer storage. The urine HGFIN-to-creatinine ratio compared favorably with the urine neutrophil gelatinase-associated lipocalin (NGAL)-to-creatinine ratio (both measured by commercial enzyme-linked immunosorbent assays (ELISAs)), and correlated strongly with proteinuria, but weakly with estimated glomerular filtration rate and serum creatinine. Thus, HGFIN may be a biomarker of progressive kidney disease.

Polymorphisms of the dopamine D2 receptor, serotonin transporter, and GABA(A) receptor beta(3) subunit genes and alcoholism in Mexican-Americans.

The etiology of alcohol dependence is a complex interaction of psychosocial and biologic factors. To study the impact of genetic factors that play an important role in an individual's vulnerability to alcohol abuse and dependence, we examined the genetic variations of the major neurotransmitter genes, including the dopamine D2 receptor (DRD2) TaqI A, B, and -141C insertion/deletion (Ins/Del) polymorphisms, the serotonin transporter-linked polymorphic region (5-HTTLPR), and the gamma-aminobutyric acid A (GABA(A)) receptor beta(3) subunit gene (GABRbeta3), for 130 Mexican-American alcoholic men and 251 nonalcoholic control subjects (105 men and 146 women). The genotype frequency for the DRD2 -141C Ins/Del allele was significantly different between alcoholic and control subjects (P=.007). The frequency of the 5-HTTLPR short (S) allele was significantly higher in alcoholic individuals (61.5%) than in nonalcoholic control subjects (52.8%; P=.021). When smokers were excluded from both control and alcoholic groups, the association between the DRD2 -141C Ins allele, as well as between the 5-HTTLPR S allele, and alcoholism became significant at both genotypic and allelic levels. No positive association was found between alcoholism and the DRD2 TaqI A or B, or the GABRbeta3, genotype. Our findings indicate that the DRD2 -141C Ins allele and the 5-HTTLPR S allele are genetic risk factors for alcoholism in Mexican-Americans, and that smoking modulates the association between genetic risk factors and alcoholism.

RXRalpha-regulated liver SAMe and GSH levels influence susceptibility to alcohol-induced hepatotoxicity.

Retinoids influence the pathogenesis of alcohol liver disease (ALD). To analyze the impact of retinoid X receptor alpha (RXRalpha) on ALD, alcohol-induced hepatotoxicity was studied using mice fed ethanol intragastrically for 25 days. Alcohol-induced microvesicular fat around the central vein and drug-induced morphological changes (loss of rough endoplasmic reticulum, pinkish cytoplasm, and enlarged hepatocyte) in the pericentral area were observed in the liver of wild-type mice. In the hepatocyte RXRalpha-deficient mouse liver, alcohol induced fat accumulation, mitosis, acute inflammation, and necrosis. The histology score after alcohol treatment was significantly higher in mutant mice than in wild-type mice. However, drug-induced morphological changes were not apparent in alcohol-treated hepatocyte RXRalpha-deficient mice. Northern analysis showed that the basal and alcohol-induced CYP2B, CYP2A, and CYP3A mRNA levels were lower in hepatocyte RXRalpha-deficient mice than in wild-type mice, which in turn may protect mutant mice from morphological changes. Compared with wild-type mice, hepatocyte RXRalpha-deficient mice have significant lower levels of S-adenosylmethionine and glutathione, which is further reduced after alcohol treatment, and that may account for severe liver injury induced by alcohol. The overall result suggests an important role of RXRalpha in preventing alcohol-induced liver injury.

The ADH3*2 and CYP2E1 c2 alleles increase the risk of alcoholism in Mexican American men.

To identify the association between the polymorphisms of genes encoding alcohol metabolizing enzymes and alcoholism, the alcohol dehydrogenase 2 (ADH2), alcohol dehydrogenase 3 (ADH3), aldehyde dehydrogenase 2 (ALDH2), and cytochrome P450 2E1 (CYP2E1) genes were studied in 101 male Mexican American alcoholics. One hundred and four Mexican American nonalcoholic males served as controls. The allele frequency of ADH2*2 (4.3%) and ALDH2*2 (0%), which are considered as protective alleles against alcohol drinking, is very low in Mexican Americans and no association is found between these alleles and alcohol dependence. A strong association was found between ADH3 genotype and alcoholism; the percentage of subjects who carry the ADH3*2 allele was significantly higher in alcoholics (64.4%) than controls (50%). Association was also found between the CYP2E1 RsaI c2 allele and alcohol dependence; the percentage of subjects who carry the RsaI c2 allele was significantly higher in alcoholics (34.7%) than in nonalcoholics (22.1%). The subjects whose alcohol drinking onset age is younger than 25 have much higher CYP2E1 c2 allele frequency than those whose alcohol drinking onset age is older than 25 (22.1% vs 15.7%). Among 101 alcoholics, only 18 subjects carry neither ADH3*2 nor CYP2E1 c2 alleles. For those subjects who have an ADH*1/*1 background, a strong association is found between CYP2E1 RsaI/DraI genotype and alcoholism; the CYP2E1 RsaI c2 and DraI C allele frequencies are much higher in alcoholics than in nonalcoholics (26.4% vs 9.6% for c2 and 27.8% vs 13.5% for C allele). Taken together, ADH3*2 and CYP2E1 c2/C alleles might independently contribute to the development of alcoholism in Mexican American men.

Hepatocyte retinoid X receptor-alpha-deficient mice have reduced food intake, increased body weight, and improved glucose tolerance.

Hepatocyte retinoid X receptor (RXR)alpha-deficient mice and wild-type mice were fed either a regular or a high-saturated-fat diet for 12 wk to study the functional role of hepatocyte RXRalpha in fatty acid and carbohydrate metabolism. Food intake was significantly reduced in hepatocyte RXRalpha-deficient mice when either diet was used. The amount of food intake was negatively associated with serum leptin level. Although mutant mice ate less, body weight and fat content were significantly higher in mutant than wild-type mice. Examination of the expression of peroxisome proliferator-activated receptor-alpha target genes indicated that the peroxisome proliferator-activated receptor-alpha-mediated pathway was compromised in the mutant mice, which, in turn, might affect fatty-acid metabolism and result in increased body weight and fat content. Although mutant mice were obese, they demonstrated the same degree of insulin sensitivity and the same level of serum insulin as the wild-type mice. However, these mutant mice have improved glucose tolerance. To explore a mechanism that may be responsible for the improved glucose tolerance, serum IGF-I level was examined. Serum IGF-1 level was significantly increased in mutant mice compared with wild-type mice. Taken together, hepatocyte RXRalpha deficiency increases leptin level and reduces food intake. Those mice also develop obesity, with an unexpected improvement of glucose tolerance. The result also suggests that an increase in serum IGF-I level might be one of the mechanisms leading to improved glucose tolerance in hepatocyte RXRalpha-deficient mice.