A murine model of acute liver injury induced by human monoclonal autoantibody

We have previously reported an immunoglobulin (Ig) M autoantibody to hepatocyte-related 190-kd molecules in patients with type 1 autoimmune hepatitis (AIH). This molecule was first isolated by hepatocyte-specific human monoclonal antibody (MoAb). To elucidate the role of this IgM autoantibody in hepatocyte injury, we examined the reactivity of this MoAb to murine hepatocytes and then questioned whether acute hepatic injury could be induced in mice via injection of this MoAb. The reactivity of MoAb was examined via both FACS analysis using murine hepatocytes and immunostaining of liver tissues. We then identified the murine hepatocyte membrane molecule recognized by this MoAb. The role of this MoAb in the immunopathogenesis of AIH was assessed by testing whether its injection into mice could increase serum aminotransferase levels as well as cause changes in liver histology. The present results demonstrate that this MoAb cross-reacted with murine hepatocytes and recognized a 190-kd molecule on the murine hepatocyte membrane just as in human hepatocytes. One hour after the injection of MoAb, the deposition of both IgM and complement component 3 was found in liver tissues. At 8 hours after the injection, serum aminotransferase levels were significantly increased in MoAb-injected mice compared with controls. Histological study revealed massive hepatocyte necrosis in MoAb-injected mice. In conclusion, human MoAb recognized a 190-kd molecule of both human and murine hepatocytes, and the injection of this MoAb to mice resulted in acute liver injury, indicating that this type of autoantibody may play an important role in the immunopathogenesis of AIH.     

Urinary vanin‐1 associated with chronic kidney disease in hypertensive patients: A pilot study

Hypertension and chronic kidney disease (CKD) are serious interrelated public health problems. Despite the monitoring and control of high blood pressure, symptoms of CKD are not usually apparent in its early stages. Previously, we reported the utility of urinary vanin‐1 as an early biomarker of kidney injury in spontaneously hypertensive rats, but it remains unknown whether urinary vanin‐1 is associated with CKD in humans. In this study, we estimated associations between urinary vanin‐1 and parameters of kidney function in a cross‐sectional study of hypertensive patients. We measured concentrations of vanin‐1 using spot urine from 147 adult hypertensive patients (mean age, 72.8 years; 39.5% women). Patients were divided into 2 groups based on the median of the estimated glomerular filtration rate (eGFR). The group with eGFR < 60 mL/min per 1.73 m² showed significantly higher levels of urinary vanin‐1 than those with eGFR ≥ 60 mL/min per 1.73 m². On univariate analysis, urinary vanin‐1 as well as neutrophil gelatinase‐associated lipocalin (NGAL) showed significant negative correlations with eGFR; however, multivariate analysis revealed that urinary vanin‐1, but not NGAL, significantly correlated with eGFR. In addition, urinary vanin‐1 had a significant positive correlation with the urinary protein‐to‐creatinine ratio (UPCR) (r = 0.21; P = .021) and albumin‐to‐creatinine ratio (UACR) (r = 0.61; P < .01). In conclusion, urinary vanin‐1 is associated with lower eGFR and higher UPCR and UACR, and might be a potential marker of decreased kidney function in hypertensive patients. Further studies are needed to confirm these findings.     

Development and characterization of new microsatellite loci in the Otton frog (Babina subaspera) and cross-amplification in a congeneric species, Holst’s frog (B. holsti)

The Otton frog (Babina subaspera) and Holst’s frog (Babina holsti) are both endangered sister species belonging to family Ranidae. For extensive genetic and ecological research of these species, we isolated and characterized 8 new microsatellite loci of the Otton frog and validated cross-amplification in Holst’s frog along with 8 previously reported loci. The total number of alleles and the expected heterozygosity of newly isolated loci in the Otton frog population ranged from 5 to 12 and from 0.620 to 0.905, respectively. We also confirmed cross-amplification in 4 of the new loci and in all previously reported loci in Holst’s frog with the same level of polymorphism as the Otton frog. Our findings suggest that these novel loci will be applicable for conservation genetic studies across varying scales.     

Mechanisms underlying the modulation of L-type Ca2+ channel by hydrogen peroxide in guinea pig ventricular myocytes

Although Cav1.2 Ca²⁺ channels are modulated by reactive oxygen species (ROS), the underlying mechanisms are not fully understood. In this study, we investigated effects of hydrogen peroxide (H₂O₂) on the Ca²⁺ channel using a patch-clamp technique in guinea pig ventricular myocytes. Externally applied H₂O₂ (1 mM) increased Ca²⁺ channel activity in the cell-attached mode. A specific inhibitor of Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) KN-93 (10 μM) partially attenuated the H₂O₂-mediated facilitation of the channel, suggesting both CaMKII-dependent and -independent pathways. However, in the inside-out mode, 1 mM H₂O₂ increased channel activity in a KN-93-resistant manner. Since H₂O₂-pretreated calmodulin did not reproduce the H₂O₂ effect, the target of H₂O₂ was presumably assigned to the Ca²⁺ channel itself. A thiol-specific oxidizing agent mimicked and occluded the H₂O₂ effect. These results suggest that H₂O₂ facilitates the Ca²⁺ channel through oxidation of cysteine residue(s) in the channel as well as the CaMKII-dependent pathway.