Sodium/calcium exchange modulates intracellular calcium overload during posthypoxic reoxygenation in mammalian working myocardium. Evidence from aequorin-loaded ferret ventricular muscles.

We tested the hypothesis that the intracellular Ca2+ overload of ventricular myocardium during the period of posthypoxic reoxygenation is mediated by transsarcolemmal Ca2+ influx via Na+/Ca2+ exchange. In aequorin-loaded, ferret right ventricular papillary muscles, blockers of the sarcolemmal and the sarcoplasmic reticulum Ca2+ channels, slowed the Cai2+ transient, producing a convex ascent during membrane depolarization, followed by a concave descent during repolarization. The magnitude of the Cai2+ transient was affected by changes in the membrane potential, Nai+, Nao+, and Cao2+, and was blocked by Ni2+, or dichlorbenzamil. The calculated Na+/Ca2+ exchange current was in the reverse mode (Ca2+ influx) during the ascending phase of the Cai2+ transient, and was abruptly switched to the forward mode (Ca2+ efflux) at repolarization, matching the time course of the Cai2+ transient. During hypoxic superfusion, the Cai2+ transient was abbreviated, which was associated with a shorter action potential duration. In contrast, immediately after reoxygenation, the Cai2+ transient increased to a level greater than that of the control, even though the action potential remained abbreviated. This is the first demonstration on a beat-to-beat basis that, during reoxygenation, Ca2+ influx via Na+/Ca2+ exchange is augmented and transports a significant amount of Ca2+ into the ventricular myocardial cell. The activation of the exchanger at the time of reoxygenation appears to be mediated by Nai+ accumulation, which occurs during hypoxia.     

Successful allogeneic bone marrow transplantation for acute myelogenous leukemia after drug-induced cardiomyopathy

Anthracycline derivatives often induce cardiomyopathy. Patients with seriously decreased cardiac function due to chemotherapeutic drugs cannot usually receive allogeneic hematopoietic stem cell transplantation (SCT) for hematologic disorders. We successfully performed allogeneic bone marrow transplantation (BMT) in a patient with severe cardiomyopathy. An 18-year-old woman with relapsed acute myelogenous leukemia had cardiomyopathy due to previous anthracycline administration. She underwent allogeneic BMT from her HLA-identical brother. Her preconditioning regimen was cytosine arabinoside, etoposide, total body irradiation, and high-dose cyclophosphamide. Congestive heart failure (CHF) was not present before BMT. Right heart pressures were monitored by a pulmonary arterial balloon catheter system (Swan-Ganz catheter). After BMT, she had severe CHF, which was controlled using pimobendan and amrinone. Patients with cardiomyopathy can receive allogeneic SCT under strict hemodynamic management.     

HLA typing and transplantation

Clinical trial of organ transplantation was renal transplantation by Voronoy at 1936. The discovery of HLA in the 1950s was one of the most important new findings in the area of transplantation. Nowadays, developing HLA genotyping methods, the serum analysis does not use for donor and recipient HLA typing but for cross-matching test. Because each of HLA genotyping methods has its merits and demerits, it is important to choice right methods for avoiding type error. PCR-Luminex method using fluorescence microsphere was developed for high-resolution HLA-A, HLA-B and HLA-DRB1 genotyping in the Japanese population. This genotyping method allows to define all the possible combinations of alleles at each loci existing in Japanese at the four-digital level. In hematopoietic stem cell transplantation, to match high resolution level of HLA between donor and recipient lead an improvement of recipient's survival. In organ transplantation, removed organ has to be so immediately transplanted into recipient that no time is left for HLA genotyping. In order to have good survival of transplanted organ, HLA, cytokine promoter lesion and immunoglobulin like receptor genotyping might be helpful. We focused on this review at HLA genotyping, especially new SSO methods.     

HLA and hepatitis C virus positive cardiomyopathy

The relationship between HCV (hepatitis C virus) and the susceptibility of cardiomyopathy has been indicated, but the detailed mechanism for close association is still unknown. It is well known that the human leukocyte antigen (HLA) may regulate the development of chronic hepatitis in HCV positive patients. We have analyzed the distribution of HLA class II alleles in Japanese patients with HCV antibody positive dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM), and HLA-DPB1*0901 was significantly increased in HCV Ab positive DCM, and the HLA-DRB1*0901-DQB1*0303 haplotype was in HCV Ab positive HCM. These results suggested that molecular mechanism for the development of cardiomyopathy mediated by HCV is different between DCM and HCM.     

Uptake of triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid) and dicamba (3,6-dichloro-2-methoxybenzoic acid) from the apical membranes of the human intestinal Caco-2 cells

We investigated whether the uptake of triclopyr (3, 5, 6-trichloro-2-pyridinyloxyacetic acid) and dicamba (3,6-dichloro-2-methoxybenzoic acid) across the apical membrane of Caco-2 cells was mediated via proton-linked monocarboxylic acid transporters (MCTs). The uptake of triclopyr from the apical membranes was fast, pH-, temperature-, and concentration dependent, required metabolic energy to proceed, and was competitively inhibited by monocarboxylic acids such as benzoic acid and ferulic acid (substrates of l-lactic acid-insensitive MCTs), but not by l-lactic acid. Thus, the uptake of triclopyr in Caco-2 cells appears to be mediated mainly via l-lactic acid-insensitive MCTs. In contrast, the uptake of dicamba (a benzoic acid derivative) was slow, and it was both pH- and temperature dependent. Coincubation with ferulic acid did not decrease the uptake of dicamba, although coincubation with benzoic acid moderately decreased it. The uptake of dicamba appears to be mediated mainly via passive diffusion, which is in contrast to the uptake of benzoic acid via MCTs. We speculate that the substituted groups in dicamba may inhibit uptake via MCTs.     

NFKBIL1 confers resistance to experimental autoimmune arthritis through the regulation of dendritic cell functions

We and others have reported that human NF-κB inhibitor-like-1 (NFKBIL1) was a putative susceptible gene for autoimmune diseases such as rheumatoid arthritis (RA). However, its precise role in the pathogenesis of RA is still largely unknown. In this study, we generated transgenic mice expressing human NFKBIL1 (NFKBIL1-Tg) and examined whether NFKBIL1 plays some role(s) in the development of autoimmune arthritis. In both a collagen-induced arthritis model and a collagen antibody-induced arthritis model, NFKBIL1-Tg mice showed resistance to arthritis compared to control mice, indicating that the gene product of NFKBIL1 was involved in the control of thusly induced arthritis. Total spleen cells of NFKBIL1-Tg mouse showed decreased proliferation to mitogenic stimuli, consistent with its resistance to arthritis. Unexpectedly, purified T cells of NFKBIL1-Tg mouse showed increased proliferation and cytokine production. This apparent discrepancy was accounted for by the impaired functions of antigen-presenting cells of NFKBIL1-Tg mouse; both T/B cell-depleted spleen cells and bone marrow-derived dendritic cells of the Tg mouse induced less prominent proliferation and IL-2 production of T cells. Furthermore, dendritic cells (DCs) derived from NFKBIL1-Tg mouse showed lower expression of co-stimulatory molecules and decreased production of inflammatory cytokines when they were activated by lipopolysaccharide. Taken together, these results indicated that NFKBIL1 affected the pathogenesis of RA at least in part through the regulation of DC functions.     

Association of autoimmune disease-related gene polymorphisms with chronic graft-versus-host disease

Chronic graft-versus-host disease (GVHD) is the most common cause of poor outcomes after haematopoietic stem cell transplantation (HSCT), while the pathophysiology of chronic GVHD remains poorly understood. As both chronic GVHD and autoimmune disease share clinical features, we speculated that autoimmune disease-related genes might be candidate chronic GVHD-related genes. Recent large-scale cohort studies showed that Fc receptor-like 3 gene (FCRL3) single nucleotide polymorphism (SNP) and peptidylarginine deiminases citrullinating enzymes 4 gene (PADI4) haplotype were associated with autoimmune disease. The present study investigated the association between polymorphisms of these two genes and the incidence of chronic GVHD. We analysed 123 cases of Japanese human leucocyte antigen-matched sibling recipients and their donors who underwent HSCT. Although PADI4, which is the rheumatoid arthritis-specific related gene, was not associated with the occurrence of chronic GVHD, the recipient FCRL3-169C/C genotype was significantly less frequent in chronic GVHD patients than in those without chronic GVHD (P = 0.0086). There was no relationship between FCRL3 polymorphism and acute GVHD. As FCRL3 is expressed by B cells and might have an important role in immunoregulation, this significant protective genetic effect raises the question of whether FCRL3 might also be involved in the pathogenesis of chronic GVHD.     

Genetic polymorphisms of the major histocompatibility complex-encoded antigen-processing genes TAP and LMP in sarcoidosis

Sarcoidosis is a granulomatous disease showing a significant increase in the HLA-DR5, -DR6, and -DR8 associated alleles in Japanese. To investigate whether the class I antigen-processing genes, encoded within the MHC class II region between the HLA-DP and -DQ loci, are involved in determining the susceptibility to Sarcoidosis, TAP1, TAP2, and LMP2 alleles were analyzed by the PCR-RFLP method in 85 Japanese patients with Sarcoidosis and 91 healthy controls.

There were no significant differences in the distribution of TAP1 and LMP2 alleles between the subgroups of the patients and controls positive or negative for DR5, DR6, and DR8. A significant decrease in the frequency of TAP2*0201 was found among the patients negative for DR5, DR6, and DR8 as compared to the DR-matched controls (p < 0.05), but this could be explained by its linkage disequilibrium to the negatively associated allele DR1. These findings suggest that the TAP or LMP2 gene is not primarily involved in the susceptibility to Sarcoidosis. In the course of this study, a linkage disequilibrium was observed in the Japanese population between TAP1 and TAP2 alleles, TAP1*0201 and TAP2*0102.     

Autoreactive CD8+ cytotoxic T lymphocytes to major histocompatibility complex class I chain-related gene A in patients with Behçet's disease

OBJECTIVE: To detect and characterize the autoreactive CD8+ T cells to major histocompatibility complex class I chain-related gene A (MICA), a stress-inducible antigen preferentially expressed on the epithelium and endothelium, in patients with Behcet's disease (BD). METHODS: A candidate for the antigenic MICA peptide was selected based on its predicted binding affinity for HLA-B51 and proteasomal cleavage sites. Peripheral blood T cells from 14 patients with BD and 15 healthy controls were repeatedly stimulated with the MICA peptide, and the specific T cell response was measured by peptide-induced interferon-gamma. Cytotoxic T lymphocyte activity was examined by chromium-51 release from an HLA-B51-transfected B cell line in the presence of the MICA peptide. RESULTS: A 9-mer peptide AAAAAIFVI (termed MICA transmembrane [MICA-TM]) was selected as a candidate for the antigenic peptide presented by HLA-B51. A specific T cell response to MICA-TM was detected in 4 patients with BD (29%) but in none of the 15 healthy donors. All 4 responders had HLA-B51 and active disease, and the specific T cell response was lost after the BD-related symptoms disappeared. The MICA-induced T cell response was specifically inhibited by anti-HLA class I antibody or by CD8+ cell depletion. MICA-reactive T cells recognized an HLA-B51-transfected B cell line pulsed with MICA-TM or a B cell line transfected with both HLA-B51 and MICA in the absence of exogenous peptides. Finally, MICA-stimulated T cell lines lysed the HLA-B51-expressing B cell line in the presence of MICA-TM. CONCLUSION: HLA-B51-restricted cytotoxic T lymphocytes autoreactive to MICA may be involved in the pathogenesis of BD.