Long-term heat exposure prevents hypoxia-induced apoptosis in mouse fibroblast cells.

Long-term continuous exposure to high ambient temperatures induces complete heat acclimation in humans and animals. However, to date, the effects of long-term exposure to heat stress on cells have not been fully evaluated. In this study, we investigated an adaptive physiological process induced in culture cells by continuous exposure to mild heat stress for 60 days. The results of this investigation provide evidence that after long-term heat acclimation in cells, (1) heat shock protein levels are increased, (2) hypoxia inducible factor-1α (HIF-1α) expression is upregulated, and (3) heat shock-induced and hypoxia-induced apoptoses are attenuated. These results suggest that the hypoxia response pathway is an intrinsic part of the heat acclimation repertoire and that the HIF-1 pathway following long-term heat acclimation induces cells with cross tolerance against hypoxia.

Upregulation of aquaporin expression in the salivary glands of heat-acclimated rats.

It is known that aquaporin (AQP) 5 expression in the apical membrane of acinar cells in salivary glands is important for the secretion of saliva in rodents and humans. Although heat acclimation enhances saliva secretion in rodents, the molecular mechanism of how heat induces saliva secretion has not been determined. Here, we found that heat acclimation enhanced the expression of AQP5 and AQP1 in rat submandibular glands concomitant with the promotion of the HIF-1α pathway, leading to VEGF induction and CD31-positive angiogenesis. The apical membrane distribution of AQP5 in serous acinar cells enhanced after heat acclimation, while AQP1 expression was restricted to the endothelial cells in the submandibular glands. A network of AQPs may be involved in heat-acclimated regulation in saliva secretion. Because AQPs probably plays a crucial role in saliva secretion in humans, these findings may lead to a novel strategy for treating saliva hyposecretion.

Targeted activation of PKA and Epac promotes glioblastoma regression in vitro.

Ras-p44/42 mitogen-activated protein kinase (MAPK) and Akt signaling are the key pathways involved in the promotion of glioblastoma formation. Notably, phosphodiesterase 4 (PDE4) is widely expressed in brain tumors and promotes their growth. PDE4 inhibitors have been reported to suppress glioblastoma growth in vitro and in vivo. The mechanisms underlying these actions, however, have yet to be elucidated. The aim of this study was to investigate whether intracellular cyclic adenosine monophosphate (cAMP) was able to suppress the Ras-p44/42 MAPK signaling pathway via protein kinase A (PKA) and exchange protein directly activated by cAMP (Epac) in U87MG human malignant glioma cells. Forskolin, an activator of adenylate cyclase, inhibited cell growth and the phosphorylation of p44/42 MAPK in U87MG cells, whereas the non-hydrolyzable cAMP analog 8-bromoadenosine 3',5'-cAMP (8-Br-cAMP) considerably suppressed cell growth and phosphorylation of p44/42 MAPK. The inhibitory effects of forskolin were partially prevented by the PKA inhibitor H89. The Epac-selective agonist 8-(4-chlorophenylthio)-2'-O-methyladenosine cAMP (8-CPT-cAMP) inhibited phosphorylation of p44/42 MAPK. These findings suggest that PKA and Epac are involved in the effect of intracellular cAMP on the Ras-p44/42 MAPK signaling pathway.

Cellular heat acclimation regulates cell growth, cell morphology, mitogen-activated protein kinase activation, and expression of aquaporins in mouse fibroblast cells.

The heat shock response has been extensively studied by a number of investigators to understand the molecular mechanism underlying the cellular response to severe heat stress (higher than 42°C). But, body or tissue temperature increases by only a few degrees Celsius during physiological events. Therefore, the physiological cellular response to mild heat stress rather than severe heat stress is likely to be more important. Repeated exposure to hyperthermia for consecutive 5 days induces heat acclimation which is an adaptive physiological process in humans and animals. However, thus far, the effect of continuous exposure to heat stress on cells has not been fully evaluated. In this study, we investigated an adaptive physiological process that is induced in culture cells by continuous exposure to mild heat stress for 5 days. Exposure to heat activated p38-mitogen-activated protein kinase; inhibited cell growth without apoptosis; and increased the levels of HSPs and HSF-1 in mouse fibroblast cells. Interestingly, exposure to heat regulated the expression of aquaporins and induced morphological change. In a physiological sense, these results suggested that continuous exposure to mild heat stress for 5 days, in which heat acclimation is attained in humans and animals, might induce molecular adaptation to heat in cells.

Phosphodiesterase inhibitors suppress Lactobacillus casei cell-wall-induced NF-κB and MAPK activations and cell proliferation through protein kinase A--or exchange protein activated by cAMP-dependent signal pathway.

Specific strains of Lactobacillus have been found to be beneficial in treating some types of diarrhea and vaginosis. However, a high mortality rate results from underlying immunosuppressive conditions in patients with Lactobacillus casei bacteremia. Cyclic AMP (cAMP) is a small second messenger molecule that mediates signal transduction. The onset and progression of inflammatory responses are sensitive to changes in steady-state cAMP levels. L. casei cell wall extract (LCWE) develops arteritis in mice through Toll-like receptor-2 signaling. The purpose of this study was to investigate whether intracellular cAMP affects LCWE-induced pathological signaling. LCWE was shown to induce phosphorylation of the nuclear factor κB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways and cell proliferation in mice fibroblast cells. Theophylline and phosphodiesterase inhibitor increased intracellular cAMP and inhibited LCWE-induced cell proliferation as well as phosphorylation of NF-κB and MAPK. Protein kinase A inhibitor H89 prevented cAMP-induced MAPK inhibition, but not cAMP-induced NF-κB inhibition. An exchange protein activated by cAMP (Epac) agonist inhibited NF-κB activation but not MAPK activation. These results indicate that an increase in intracellular cAMP prevents LCWE induction of pathological signaling pathways dependent on PKA and Epac signaling.

Activation of tumor suppressor protein PTEN and induction of apoptosis are involved in cAMP-mediated inhibition of cell number in B92 glial cells.

During brain development, cAMP induces morphological changes and inhibits growth effects in several cell types. However, the molecular mechanisms underlying the growth inhibition remain unknown. Tumor suppressor protein phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a lipid phosphatase that inhibits the phosphoinositide 3-kinase (PI3K) pathway. The phosphorylation of Akt, which is one of the key molecules downstream of PI3K, inhibits apoptosis. In this study, we investigated the role of PTEN in cAMP-mediated growth inhibition. B92 rat glial cells were treated with 2 different cAMP stimulatory agents, a phosphodiesterase (PDE) inhibitor and a ß-adrenoceptor agonist. Both cAMP stimulatory agents induced marked morphological changes in the cells, decreased cell number, decreased Akt phosphorylation, activated PTEN, cleaved caspase-3, and induced the condensation and fragmentation of nuclei. These results indicate that the cAMP stimulatory agents induced apoptosis. Protein phosphatase inhibitor prevented cAMP-induced dephosphorylation of PTEN and Akt. In addition, cAMP analogs and Epac-selective agonists affected PTEN and Akt activities. These results suggested that cAMP-induced apoptosis may be mediated by PTEN activation and Akt inhibition through protein phosphatase in B92 cells. Our results provide new insight into the role of PTEN in cAMP-induced apoptosis in glial cells.

Urinary heme oxygenase-1 as a sensitive indicator of tubulointerstitial inflammatory damage in various renal diseases.

BACKGROUND/AIMS: In oxidative stress, heme oxygenase-1 (HO-1) plays a pivotal role in maintaining renal function and protecting renal structure, especially in renal tubular epithelial cells. We examined urinary HO-1 (uHO-1) levels to assess whether uHO-1 acts as a sensitive biomarker for detecting tubulointerstitial inflammatory damage in renal diseases. METHODS: Immunohistochemical analyses and enzyme-linked immunosorbent assays for uHO-1 were performed using 61 urine samples (supernatants and sediment lysates) from healthy children and renal disease patients. RESULTS: Proximal and distal epithelial cells showed higher uHO-1 levels than squamous and urothelial cells. Inflammatory renal disease patients had higher uHO-1 levels than noninflammatory renal disease patients and controls. In IgA nephropathy, patients with interstitial cellular infiltration showed higher uHO-1 levels than those without it. Among patients with increased urinary ß(2)-microglobulin or N-acetyl-ß-D-glucosaminidase levels, uHO-1 levels increased only in those with renal disease and tubulointerstitial inflammatory damage. uHO-1 levels positively correlated with urinary interleukin-6 in inflammatory renal disease patients. CONCLUSIONS: These results indicate that uHO-1 is a potentially useful, novel, and noninvasive biomarker for evaluating the degree of tubulointerstitial inflammatory damage in renal disease.

Aplastic anemia successfully treated with rituximab: the possible role of aplastic anemia-associated autoantibodies as a marker for response.

A 1-yr-old Japanese male infant developed hepatitis-associated aplastic anemia (AA), and anti-thymocyte globulin (ATG) plus cyclosporine A (CsA) was administered without any appreciable effects. Laboratory examination of the patient's serum obtained before therapy revealed various autoantibodies, such as PA-IgG, anti-platelets, anti-single-stranded DNA (ssDNA), and anti-double-stranded DNA (dsDNA) antibodies (Abs) in addition to anti-DRS-1 Abs and anti-moesin Abs, both of which are known to be detectable in approximately 40% of all patients presenting with AA. He was therefore treated with 17.5 mg/kg/d rituximab 5.5 months after ATG/CsA therapy. The same rituximab therapy was repeated three times once a month thereafter. His neutrophil counts started to increase 50 d after the first rituximab therapy and he achieved a complete remission at 16 months after the last rituximab administration. All of the autoantibodies including anti-ssDNA, dsDNA, DRS-1, and moesin became undetectable when he attained the remission. Anti-CD20 monoclonal antibody therapy may be effective in a subset of patients with AA characterized by the presence of autoantibodies.

Dense methylation of types 1 and 2 regulatory regions of the CD10 gene promoter in infant acute lymphoblastic leukemia with MLL/AF4 fusion gene.

SUMMARY: Infant acute lymphoblastic leukemia (ALL) displays distinct biologic and clinical features with a poor prognosis. The CD10-negative immunophenotype of infant ALL is a hallmark and provides a predictable signature of mixed-lineage leukemia (MLL) rearrangement. Although CD10 negativity reflects an earlier stage of B-cell development, complete IgH gene rearrangements (VDJH), found in almost half of the patients, show more mature IgH status. Discordance between immunophenotype and genotype of infant ALL suggests an aberrant process in immunophenotypic steps of differentiation or a secondary down-regulation of CD10 expression. In this study, CD10-negative infant ALL with MLL/AF4, CD10-positive infant ALL with germline MLL, CD10-positive pre-B ALL cell line, infant acute myeloid leukemia (AML; M5) with MLL/AF9 and pediatric AML (M2) with AML1/ETO were analyzed for VDJH status and methylation of CD10 gene promoters. Three of the 4 infant ALL samples showed complete rearrangements of the VDJH gene with productive joints. Bisulfite sequencing of CD10 type 1 and 2 promoters showed that more than 84% of the cytosine-phosphate-guanine (CpG) dinucleotides identified were methylated in all 3 CD10-negative infant ALL samples with MLL/AF4. The CpG dinucleotides distributed in the clusters of putative Sp1-binding sites and functionally active regulatory regions of the promoters were fully methylated. In contrast, none of the CpG dinucleotides were methylated in the CD10-positive ALL samples. Structural evidence of dense methylation in the CD10 gene promoter suggested that methylated transcription factor binding sites contribute to CD10 silencing as an epigenetic mechanism.

Detection of T lymphocytes with a second-site mutation in skin lesions of atypical X-linked severe combined immunodeficiency mimicking Omenn syndrome.

X-linked severe combined immunodeficiency (XSCID) is caused by mutations of the common gamma chain (gammac) and usually characterized by the absence of T and natural killer (NK) cells. Here, we report an atypical case of XSCID presenting with autologous T and NK cells and Omenn syndrome-like manifestations. The patient carried a splice-site mutation (IVS1+5G>A) that caused most of the mRNA to be incorrectly spliced but produced normally spliced transcript in lesser amount, leading to residual gammac expression and development of T and NK cells. The skin biopsy specimen showed massive infiltration of revertant T cells. Those T cells were found to have a second-site mutation and result in complete restoration of correct splicing. These findings suggest that the clinical spectrum of XSCID is quite broad and includes atypical cases mimicking Omenn syndrome, and highlight the importance of revertant mosaicism as a possible cause for variable phenotypic expression.

Study of nasopharyngeal bacterial flora. Variations in nasopharyngeal bacterial flora in schoolchildren and adults when administered antimicrobial agents.

Changes in nasopharyngeal bacterial flora in adults with acute upper respiratory tract infection on administration of antimicrobial agents were investigated, and how these changes contrasted with those in children. Many patients with acute sinusitis due to allergies, and patients with malignancy and diabetes mellitus were included in the investigation. The detection rates of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis, the major bacteria of acute otitis media (AOM), were 22%, 10%, and 7% respectively, which were significantly lower than those for children. Gram stain examination of nasopharyngeal swab samples showed a significant relation between leukocyte infiltration and the detection amount of S. pneumoniae (P = 0.0086). A significant relation (P = 0.0134) was also observed when H. influenzae was simultaneously detected. No significant change in the three major AOM bacteria present in nasopharyngeal bacterial flora after administration of antimicrobial agents was observed. However, all S. pneumoniae and H. influenzae detected after antimicrobial agent administration had the beta-lactam-resistance gene. It was observed that a significant improvement in leukocyte infiltration occurred 6 to 10 days after antimicrobial agent administration. In contrast, a significant improvement in children was observed at 2 to 5 days. In the adult subjects, this improvement was probably due to spontaneous remission rather than the effect of the antimicrobial agents. Although investigation of the long-term administration of antimicrobial agents was also conducted, its benefits for the patients were not elucidated.

Skin infiltration of CD56(bright) CD16(-) natural killer cells in a case of X-SCID with Omenn syndrome-like manifestations.

We observed a patient with X-linked severe combined immunodeficiency (X-SCID) with Omenn syndrome-like manifestations. X-linked inheritance, absence of CD132 expression and impaired response to interleukin-2 (IL-2) indicated that the case is typical of X-SCID due to gamma(c) defect. However, this case was unusual in that circulating natural killer (NK) cells were increased and nearly half of these NK cells exhibited the CD56(bright) CD16(-) phenotype. A missense mutation was found within exon 5 of the IL2RG gene. The identical mutation was detected within NK, CD4(+) T and B cells. Engraftment of maternally derived NK cells or gene reversion was ruled out. The erythroderma-like skin lesion was characterized by infiltration of the dermis by CD56(bright) NK cells admixed with CD1a(+) dendritic cells (DC). Expression of mRNA for inflammatory cytokines was significantly enhanced within the skin. This may be the first human case to demonstrate that close cell-to-cell contact between DC and NK cells provides an effective alternative pathway for NK cell differentiation/activation in vivo.

Corticosteroid enhances heme oxygenase-1 production by circulating monocytes by up-regulating hemoglobin scavenger receptor and amplifying the receptor-mediated uptake of hemoglobin-haptoglobin complex.

This study examined the relationship between steroid treatment and CD163-mediated downstream pathways linked to inflammatory resolution. Twelve patients referred for congenital heart disease surgery were divided into two groups based on the severity of intravascular hemolysis during cardiopulmonary bypass surgery. Patients with severe intravascular hemolysis were administered haptoglobin during the procedure. Flow cytometry indicated a peak in monocyte CD163 expression on post-operative day 1 in both groups. Enhanced and prolonged heme oxygenase-1 (HO-1) mRNA expression levels were observed in patients who received haptoglobin. Binding of hemoglobin-haptoglobin complex (Hb/Hp) to CD163 resulted in significant induction of HO-1 by peripheral blood mononuclear cells after exposure to dexamethasone prior to culture. This effect was significantly inhibited by anti-CD163 antibody. Our results demonstrated up-regulation of CD163 expression on the monocyte surface by steroid treatment. Steroid treatment was suggested to facilitate CD163-mediated endocytosis of hemoglobin to monocytes/macrophages and thereby induce acceleration of HO-1 synthesis.

Reactive peripheral blood plasmacytosis in a patient with acute hepatitis A.

Reactive plasmacytosis is a transient expansion of plasma cell progenitors and precursors. This rare condition has been reported to occur mainly in infections and tumors. We describe a case of acute hepatitis A presenting with marked peripheral blood plasmacytosis. Plasma cells made up 27.5% of the mononuclear cells and had the immunophenotype CD10-CD19+CD20-CD21-CD23-CD34-CD38++HLA-DR+. Although the level of interleukin 6 was not increased, the presence of activated T-cells with an inverted CD4/CD8 ratio and high levels of soluble interleukin 2 receptor and neopterin indicated a marked immune response to acute hepatitis A. The patient's plasma cells had almost disappeared from the blood by hospital day 16. This report may represent the first described case of reactive peripheral blood plasmacytosis in acute hepatitis A.