Sequence of four new HLA-Cw alleles: a possible role of interallelic recombination

Abstract: In order to extend our current understanding of HLA-C polymorphism, four new alleles have been cloned and sequenced: Cw*1801 in a donor of mixed origin, Cw*02024 in a Senegalese individual, Cw*1205 and Cw*1604 in European Caucasoid blood donors. HLA-Cw*1801, which most likely results from an interallelic recombination between Cw*0704 and 0401 alleles, was not associated with B*8101, but with either B*4403 or B18. The Cw*02024 allele differs from Cw*02022 by a silent mutation in exon 3. Both Cw*1801 and Cw*02024 appear to be rather frequent in populations of African origin but have not yet been detected in Caucasoids. HLA-Cw*1604 differs from Cw*1601 by two nucleotides at codon 156 leading to a Gln to Trp substitution. This new Cw16 subtype was subsequently identified in three additional unrelated families, all of South-European origin, and presented an unusual association with B*4402 in all cases. HLA-Cw*1205 is a composite allele with the α1 domain of Cw*1602 and the α2 domain of Cw*1203. It appears to be rare, at least in European Caucasoids. Three of these four alleles may have resulted from gene conversion-like or interallelic recombination events.     

The role of pyruvate carboxylase in insulin secretion and proliferation in rat pancreatic beta cells

Aims/hypothesis  Pyruvate carboxylase (PC) or pyruvate dehydrogenase (PDH) is required to transfer carbons from pyruvate into the Krebs cycle. PC activity is preserved in the islets of obese animals, but it is reduced in the islets of animal models of type 2 diabetes, suggesting that PC is important in beta cell adaptation to insulin resistance and that PC reduction may lead to beta cell failure. Methods  To confirm the significance of PC, we first lowered activity using Pc (now known as Pcx) small interfering RNA (siRNA) in INS-1 cells and in dispersed rat islet cells. Second, we overexpressed PC in INS-1 cells, and third, we inhibited PDH by overexpressing the gene encoding pyruvate dehydrogenase kinase 4 (Pdk4) in INS-1 cells. Results  Treatment of INS-1 cells or dispersed rat islet cells with Pc siRNA resulted in a significant reduction in insulin secretion in both cell types and reduced proliferation in INS-1 cells. This treatment also reduced the content of oxaloacetate, malate and ATP, as well as the NADPH:NADP⁺ ratio and activity of the pyruvate–malate shuttle. Overexpression of PC in INS-1 cells led to an elevation of insulin secretion and cell proliferation, whereas inhibition of PDH activity by overexpressing Pdk4 in INS-1 cells did not reduce insulin secretion. Conclusions/interpretation  Our findings indicate that the PC pathway in beta cells might play a key role in pyruvate metabolism, insulin secretion and cell proliferation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorised users. J. Xu and J. Han contributed equally to this study.     

Prevalence and characteristics of psoriatic arthritis in Chinese patients with psoriasis

Background The prevalence and clinical characteristics of psoriatic arthritis (PsA) in patients with psoriasis vary widely in different countries and studies on Chinese population are rarely reported. Objective The aim of this study was to evaluate the prevalence and clinical characteristics of PsA in a Chinese population of patients with psoriasis. Methods A large cross‐sectional observational study was conducted in our outpatient dermatology department and consecutive psoriatic patients were evaluated for PsA according to Classification of Psoriatic arthritis (CASPAR) criteria. Demographic and medical parameters were recorded. Results Among 1928 patients with psoriasis, 112 patients (5.8%) had PsA, of which 92% was newly diagnosed. Oligoarthritis (48.2%) was the most common manifestation pattern, followed by spondylitis (26.8%), polyarthritis (19.6%) and classic distal interphalangeal (DIP) arthritis (5.4%). Enthesitis was present in 26.8% and dactylitis in 13.4% of the patients. Compared with patients without PsA, patients with PsA had more severe skin disease (mean PASI 9.7 vs. 6.0), higher frequency of nail changes (46.4% vs. 21.0%) and scalp involvement (90.2% vs. 76.4%). Conclusion The findings are consistent with a low prevalence of PsA among patients with psoriasis in Asia and confirm a high percentage of undiagnosed cases with active arthritis among PsA patients in dermatologist’s office. Dermatologists should screen for PsA in their patients, especially those with risk characteristics and early signs.     

Selective suppression of granuloma formation and delayed hypersensitivity in rabbits

The relationship between dermal delayed hypersensitivity (DH) and granulomatous hypersensitivity was studied in rabbits sensitized with killed mycobacteria. Specific antigen challenge of sensitized animals resulted in extensive pulmonary granulomatous inflammation and induced suppression of both dermal DH and dermal granuloma formation. Whereas suppression of DH was concomitant with pulmonary granuloma formation, as is the case in a number of granulomatous diseases, a causal relationship between the two did not exist. Both DH and dermal granulomatous hypersensitivity were significantly suppressed whether or not the antigen challenge was of a granulomagenic (particulate) or nongranulomagenic (soluble) form. The data presented indicate that granulomatous hypersensitivity and DH are selectively suppressed with regard to different anatomical sites.     

PTEN hypermethylation profiles of Chinese Kazakh patients with esophageal squamous cell carcinoma

Aberrant DNA methylation of promoter region CpG islands may serve as an alternative mechanism to genetic defects in the inactivation of tumor suppressor genes (TSGs) in human malignancies. The aim of this study was to examine the promoter methylation status of the PTEN TSG and its association with esophageal squamous cell carcinoma (ESCC) carcinogenesis in a Chinese Kazakh population, which is known to have a relatively high ESCC incidence and mortality. The methylation status of the PTEN promoter region was determined in patients with ESCC (n = 95) and healthy individuals (n = 65) using highly sensitive Sequenom Epityper assays. The methylation level of the PTEN gene was significantly higher in patients with ESCC than in healthy controls. The median methylation level was 10.0% (interquartile range [IQR]: 7.0–11.0%) in patients with ESCC and 6.0% in controls (IQR: 4.0–9.0%; P = 0.001). PTEN methylation levels were higher in male patients with ESCC than in male controls, whereas a trend toward significance was observed between female patients with ESCC and female controls (P = 0.005 and P = 0.086, respectively). The PTEN methylation level was associated with histopathological grade and lymph node metastasis in patients with ESCC (P = 0.002 and P = 0.009, respectively). To our knowledge, this is the first report to show the presence of PTEN promoter CpG hypermethylation in ESCC and its association with tumor metastasis.     

Expression and estrogen regulation of brain-derived neurotrophic factor gene and protein in the forebrain of female prairie voles

Brain-derived neurotrophic factor (BDNF) has been linked to the development, differentiation, and plasticity of the central nervous system. In the present study, we first used a highly specific affinity-purified antibody and a cRNA probe to generate a detailed mapping of BDNF immunoreactive (BDNF-ir) staining and mRNA labeling throughout the forebrain of female prairie voles. Our data revealed that (1) BDNF-ir cells were present essentially in the brain regions in which BDNF mRNA-labeled cells were found; (2) BDNF-ir fibers were distributed extensively throughout many forebrain regions; and (3) BDNF mRNA was also detected in some thalamic regions in which BDNF-ir fibers, but not immunostained cells, were present. With few exceptions, the distribution pattern of BDNF in the vole brain generally resembled the pattern found in rats. In a second experiment, we examined the effects of estrogen on BDNF expression. Ovariectomized prairie voles that were treated with estradiol benzoate had a higher level of BDNF mRNA labeling in the dentate gyrus and CA3 region of the hippocampus, as well as in the basolateral nucleus of the amygdala, than did ovariectomized voles that were treated with vehicle. In addition, estrogen treatment increased the density of BDNF-ir fibers in the lateral septum, dorsolateral area of the bed nucleus of the stria terminalis, and lateral habenular nucleus. These data suggest that estrogen may regulate BDNF at the level of gene and protein expression, and thus, BDNF may be in a position to mediate the effects of estrogen on the brain of the prairie vole.     

Expression of 5-HT2A receptor mRNA in rat spinal dorsal horn and some nuclei of brainstem after peripheral inflammation

The expression of 5-hydroxytryptamine 5-HT2A receptor mRNA was studied in the lumbar spinal dorsal horn, nucleus of raphe magnus (NRM), ventrolateral periaqueductal gray (vlPAG) and dorsal raphe nucleus (DRN) following carrageenan inflammation using in situ hybridization technique. The findings of this study demonstrated that 5-HT2A receptor mRNA was expressed with low to moderate levels in lumbar spinal dorsal horn, NRM, vlPAG and DRN. Following carrageenan inflammation, the expression of 5-HT2A receptor mRNA in ipsilateral dorsal horn, bilateral NRM, vlPAG and DRN was significantly increased. The peak occurred at 3 h and then there was a clear decrease but still a substantial number of labeled cells at 24 h after injection of carrageenan. This result suggested that the synthesis of 5-HT2A receptor is enhanced in spinal dorsal horn, NRM, vlPAG and DRN during inflammatory pain.     

Partial and generalized epilepsy with febrile seizures plus and a novel SCN1A mutation.

BACKGROUND: Generalized epilepsy with febrile seizures plus (GEFS+) is an autosomal dominant syndrome characterized by febrile seizures (FS) and a variety of afebrile generalized seizure types. GEFS+ has previously been linked to mutations in two genes encoding the voltage-gated sodium channel alpha-subunit (SCN1A) and beta1-subunit (SCN1B). We studied a large family with FS and partial as well as generalized seizure types. METHODS: All but two living affected family members were interviewed and examined. Information on deceased affected family members was sought. EEG for 11 affected family members and one unaffected family member were obtained. Genetic linkage analysis and mutation screening of SCN1A were performed on blood samples from 16 affected individuals and their first-degree relatives. RESULTS: There were 27 affected family members; 18 were alive at the time of the study. All affected family members had FS; seven had FS only, and 19 also had afebrile seizures. Eleven individuals continued to have FS beyond 6 years of age. FS were complex in 12 family members, usually with prolonged duration. The index patient had right temporal lobe epilepsy and hippocampal sclerosis. Four other patients had strong historical evidence of temporal lobe epilepsy, and three others had nonlocalizing evidence of partial epilepsy. Pedigree analysis indicated autosomal dominant transmission. All affected individuals who were tested and one asymptomatic individual had a sodium channel mutation of SCN1A, an A-->C transversion at nucleotide 3809 resulting in the substitution of lysine 1270 by threonine in the D3/S2 segment (designated as K1270T). CONCLUSIONS: Our findings indicate that partial epilepsy preceded by FS can be associated with sodium channel mutations and may represent a variant of GEFS+.     

A serum factor enhances production of nitric oxide and tumor necrosis factor-alpha from cultured microglia

The pathological activation of microglia has been implicated in ischemic neuronal damage and some neurodegenerative diseases; however, the mechanism of microglial activation is not well understood. Previously, we showed that a serum factor, albumin, increased O(2)(-) production by cultured microglia (Si et al., 1997, Glia 21: 413-418). In the present study, we found that serum also enhanced lipopolysaccharide (LPS)-induced production of nitric oxide and tumor necrosis factor-alpha, which are other important neurotoxins released by activated microglia. In the presence of 0.1% normal rat serum, the half-effective concentration for LPS decreased from 300 to 1 ng/ml. The factor seemed to be a relatively high-molecular-weight protein because the factor was retained after a molecular sieve (50 kDa) membrane separation. The factor was labile to trypsinization and heat treatment at 72 degrees C for 5 min but was stable at 56 degrees C for 60 min. Several purified serum proteins including albumin could not mimic the enhancing effect of serum. Acute-phase serum showed a potent enhancing effect at a 10 times lower concentration than the normal serum. By gel filtration chromatography, the enhancing effect observed was a single peak at about 60 kDa. These results suggest that some serum protein infiltrates into brain parenchyma after blood-brain barrier disruption and such protein may result in neuronal damage by activating microglia to release neurotoxins in some central nervous system diseases.     

Low brain glutathione and ascorbic acid associated with dopamine uptake inhibition during rat's development induce long-term cognitive deficit: relevance to schizophrenia

Schizophrenia is associated with a cerebral glutathione deficit, which may leave the brain susceptible to oxidants. To study the consequences of a glutathione deficit, we treated developing rats with L-buthionine-(S,R)-sulfoximine (BSO), an inhibitor of glutathione synthesis, and later investigated their behaviour until adulthood. Since rodents may in some occasions compensate for a glutathione deficit by ascorbic acid (AA), we used Osteogenic Disorder Shionogi (ODS) mutant rats, which like humans, cannot synthetize ascorbic acid. Moreover, as hyperactivity of the dopaminergic system may be associated with schizophrenia, some rats were treated with the dopamine uptake inhibitor GBR 12909. Whereas ODS rats treated with either BSO or GBR 12909 alone had normal behaviour, rats treated with both BSO and GBR 12909 failed to discriminate between familiar and novel objects although other behaviours proved to be normal. In contrast, nonmutant rats were not affected by treatment with BSO and GBR 12909. Our results suggest that low brain glutathione and ascorbic acid levels associated with a perturbation of the dopaminergic system actively participate in the development of some cognitive deficits affecting schizophrenic patients.