Evaluation of frequency of autoimmune hepatitis autoantibodies in children with type 1 diabetes / Frecuencia de anticuerpos de hepatitis autoinmune en niños con diabetes tipo I

Background: Diabetes mellitus type 1 (T1DM) is one of the childhood diseases with growing prevalence. Various accompanying autoimmune diseases were seen with type 1 diabetes. The most common autoimmune diseases with T1DM are autoimmune thyroiditis and celiac disease. In some reports, autoimmune hepatitis has been reported in association with DM-1. Objectives: The aim of this study was to evaluate autoimmune hepatitis autoantibodies in children with T1DM. Materials and methods: In this crosssectional study, 202 children with T1DM were evaluated (47.5% were males and 52.5% were girls). Liver enzymes, autoimmune hepatitis related autoantibodies such as anti-nuclear antibodies (ANA), anti-smooth muscle (ASMA) and anti liver and kidney microsomal antibodies (LKM-1) were measured. Liver ultrasound was done for participants and biopsy of liver was taken for children with increased echogenicity of the liver, hepatomegaly or elevated liver enzymes. Results analyzed by statistical software spss-16, Descriptive statistics and chi-square test, paired T-TEST. Level of less than 5% was considered statistically significant. Results: In 6 patients ANA and in 4 patients (2%) ASMA was positive,1 patient was ASMA positive but ANA negative. None of the patients were Anti LKM-1 positive. 3 patients had positive ANA and ASMA, and increased liver echogenicity on ultrasound simultaneously. Histological evaluation was showed that 2 patients had findings in favor of autoimmune hepatitis. Conclusion: Auto antibodies were positive in 10 cases. ANA was positive in 6 (2.97%) of all cases. ASMA was positive in 4 (1.98%) cases. Increased echogenicity was found in 3 cases. Histological evaluation showed 2 patients had biopsy confirmed autoimmune hepatitis. AIH-2 was not seen among our cases.

Antecedentes: La diabetes mellitus tipo 1 (DM1) es una de las enfermedades infantiles con mayor prevalencia. Se observaron varias enfermedades autoinmunes acompañantes con diabetes tipo 1. Las enfermedades autoinmunes más comunes con DM1 son la tiroiditis autoinmune y la enfermedad celíaca. En algunos reportes, se ha encontrado hepatitis autoinmune en asociación con DM-1. Objetivos: El objetivo de este estudio fue evaluar los autoanticuerpos de hepatitis autoinmunes en niños con DM1. Materiales y métodos: En este estudio transversal, se evaluaron 202 niños con DM1 (47,5% eran hombres y 52,5% eran niñas). Se midieron las enzimas hepáticas, los autoanticuerpos autoinmunes relacionados con la hepatitis, como los anticuerpos antinucleares (ANA), el músculo liso (ASMA) y los anticuerpos microsomales hepáticos y renales (LKM-1). Se realizó una ecografía hepática para los participantes y se tomó una biopsia del hígado para niños con mayor ecogenicidad del hígado, hepatomegalia o enzimas hepáticas elevadas. Los resultados fueron analizados por el software estadístico spss-16 usando estadística descriptiva y prueba de chi-cuadrado, T-TEST pareado. Se consideró estadísticamente significativo un nivel menor del 5%. Resultados: En 6 pacientes con ANA y en 4 pacientes (2%) ASMA fue positiva, 1 paciente fue ASMA positiva pero ANA negativa. Ninguno de los pacientes fue anti LKM-1 positivo. 3 pacientes tuvieron ANA y ASMA positivas, y aumentaron la ecogenicidad hepática en la ecografía simultáneamente. La evaluación histológica mostró que 2 pacientes tenían hallazgos a favor de la hepatitis autoinmune. Conclusión: Los autoanticuerpos fueron positivos en 10 casos. ANA fue positivo en 6 (2,97%) de todos los casos. La ASMA fue positiva en 4 (1,98%) casos. Se encontró mayor ecogenicidad en 3 casos. La evaluación histológica mostró que 2 pacientes tenían biopsia confirmada de hepatitis autoinmune. AIH-2 no fue visto entre nuestros casos.

Characterization of human UGT2A3 expression using a prepared specific antibody against UGT2A3.

UDP-Glucuronosyltransferase (UGT) 2A3 belongs to a UGT superfamily of phase II drug-metabolizing enzymes that catalyzes the glucuronidation of many endobiotics and xenobiotics. Previous studies have demonstrated that UGT2A3 is expressed in the human liver, small intestine, and kidney at the mRNA level; however, its protein expression has not been determined. Evaluation of the protein expression of UGT2A3 would be useful to determine its role at the tissue level. In this study, we prepared a specific antibody against human UGT2A3 and evaluated the relative expression of UGT2A3 in the human liver, small intestine, and kidney. Western blot analysis indicated that this antibody is specific to UGT2A3 because it did not cross-react with other human UGT isoforms or rodent UGTs. UGT2A3 expression in the human small intestine was higher than that in the liver and kidney. Via treatment with endoglycosidase, it was clearly demonstrated that UGT2A3 was N-glycosylated. UGT2A3 protein levels were significantly correlated with UGT2A3 mRNA levels in a panel of 28 human liver samples (r = 0.64, p < 0.001). In conclusion, we successfully prepared a specific antibody against UGT2A3. This antibody would be useful to evaluate the physiological, pharmacological, and toxicological roles of UGT2A3 in human tissues.

Evaluation of frequency of autoimmune hepatitis autoantibodies in children with type 1 diabetes.

BACKGROUND: Diabetes mellitus type 1 (T1DM) is one of the childhood diseases with growing prevalence. Various accompanying autoimmune diseases were seen with type 1 diabetes. The most common autoimmune diseases with T1DM are autoimmune thyroiditis and celiac disease. In some reports, autoimmune hepatitis has been reported in association with DM-1. OBJECTIVES: The aim of this study was to evaluate autoimmune hepatitis autoantibodies in children with T1DM. MATERIALS AND METHODS: In this crosssectional study, 202 children with T1DM were evaluated (47.5% were males and 52.5% were girls). Liver enzymes, autoimmune hepatitis related autoantibodies such as anti-nuclear antibodies (ANA), anti-smooth muscle (ASMA) and anti liver and kidney microsomal antibodies (LKM-1) were measured. Liver ultrasound was done for participants and biopsy of liver was taken for children with increased echogenicity of the liver, hepatomegaly or elevated liver enzymes. Results analyzed by statistical software spss-16, Descriptive statistics and chi-square test, paired T-TEST. Level of less than 5% was considered statistically significant. RESULTS: In 6 patients ANA and in 4 patients (2%) ASMA was positive,1 patient was ASMA positive but ANA negative. None of the patients were Anti LKM-1 positive. 3 patients had positive ANA and ASMA, and increased liver echogenicity on ultrasound simultaneously. Histological evaluation was showed that 2 patients had findings in favor of autoimmune hepatitis. CONCLUSION: Auto antibodies were positive in 10 cases. ANA was positive in 6 (2.97%) of all cases. ASMA was positive in 4 (1.98%) cases. Increased echogenicity was found in 3 cases. Histological evaluation showed 2 patients had biopsy confirmed autoimmune hepatitis. AIH-2 was not seen among our cases.

Autoimmune hepatitis in 847 childhood-onset systemic lupus erythematosus population: a multicentric cohort study.

OBJECTIVE: To evaluate autoimmune hepatitis (AIH) in a multicenter cohort of childhood-onset systemic lupus erythematosus (cSLE) patients. METHODS: This retrospective multicenter study included 847 patients with cSLE, performed in 10 Pediatric Rheumatology services of São Paulo state, Brazil. AIH was defined according to the International Autoimmune Hepatitis Group criteria (IAHGC). The statistical analysis was performed using the Bonferroni's correction (p < 0.0033). RESULTS: AIH in cSLE patients confirmed by biopsy was observed in 7/847 (0.8%) and all were diagnosed during adolescence. The majority occurred before or at cSLE diagnosis [5/7 (71%)]. Antinuclear antibodies were a universal finding, 43% had concomitantly anti-smooth muscle antibodies and all were seronegative for anti-liver kidney microsomal antibodies. All patients with follow-up ≥18 months (4/7) had complete response to therapy according to IAHGC. None had severe hepatic manifestations such as hepatic failure, portal hypertension and cirrhosis at presentation or follow-up. Further comparison of 7 cSLE patients with AIH and 28 without this complication with same disease duration [0 (0-8.5) vs. 0.12 (0-8.5) years, p = 0.06] revealed that the frequency of hepatomegaly was significantly higher in cSLE patients in the former group (71% vs. 11%, p = 0.003) with a similar median SLEDAI-2 K score [6 (0-26) vs. 7 (0-41), p = 0.755]. No differences were evidenced regarding constitutional involvement, splenomegaly, serositis, musculoskeletal, neuropsychiatric and renal involvements, and treatments in cSLE patients with and without AIH (p > 0.0033). CONCLUSIONS: Overlap of AIH and cSLE was rarely observed in this large multicenter study and hepatomegaly was the distinctive clinical feature of these patients. AIH occurred during adolescence, mainly at the first years of lupus and it was associated with mild liver manifestations.

Microsomal glutathione transferase 2 modulates LTC4 synthesis and ROS production in Apostichopus japonicus.

Microsomal glutathione transferase 2 (mGST2) is an integral membrane protein involved in detoxication of xenobiotics, and has also been suggested to catalyze the biosynthesis of pro-inflammatory mediator leukotriene C4 (LTC4) as homologous to LTC4 synthase (LTC4S) in mammals. In the present study, a novel mGST2 homology was identified from Apostichopus japonicus (designated as AjmGST2) by RACE approaches. The full-length cDNA of AjmGST2 was of 1917bp encoding a polypeptide of 161 amino acids residues. Multiple sequences alignment and phylogenetic analysis together supported that AjmGST2 belonged to a new member in invertebrate mGSTs family and close to mammalian LTC4S. Spatial expression analysis revealed that AjmGST2 was ubiquitously expressed in all examined tissues with the larger magnitude in intestine. AjmGST2 transcripts in coelomocytes were slightly induced post 6h challenge of pathogenic Vibrio splendidus and reached the peak expression at 48h. The increased expression profiles of AjmGST2 were also detected in lipopolysaccharide (LPS) exposed primary coelomocytes. Consistently, LTC4 contents were also induced by a 1.56-fold increase in the same condition. Functional assay further revealed that AjmGST2 might be functioned as LTC4S to promote LTC4 synthesis. AjmGST2 knock-down by specific siRNA significantly depressed LTC4 contents with 27.0% decrease at 24h. Meantime, ROS levels were elevated by 40.1% in vitro. All of these results indicated that AjmGST2 performed dual functions roles as LTC4S and ROS eliminator in sea cucumber immune response.

Pituitary Microsomal Autoantibodies in Patients with Childhood-Onset Combined Pituitary Hormone Deficiency: an Antigen Identification Attempt.

The role of autoimmunization in the pathogenesis of pituitary disorders is poorly understood. The presence of pituitary autoantibodies (APA) has been detected in various pituitary disorders. Their role, however, remains elusive. Childhood-onset combined pituitary hormone deficiency (CPHD) may be caused by environmental or genetic factors. In some of patients, causes of the disease remain unclear and contributions of autoimmune processes have been postulated. The aim of this study was to identify the microsomes-derived pituitary antigens (MPA) as potential immunogenic autoantigens in patients with hypopituitarism, therefore 62 CPHD patients, 100 healthy controls and five autoimmune polyglandular syndrome type II (APS II) patients were included in the study. The clinical evaluation included hormonal tests and magnetic resonance imaging of the pituitary. The sources of MPA were pituitary glands taken from autopsies. Isolated MPA were then separated on SDS-PAGE gel and incubated with sera obtained from patients and controls. Microsomal APA were detected using Western blot and radioimmunological method. In all CPHD and APS II patients and in 9 % individuals from control group marked immunoreactivity was detected against MPA. Antibodies showed high affinity to 67, 60, 50 and 36 kDa MPAs. Since the identified autoantigens were of unknown nature, an in silico exploration of UniProt database was applied and indicated their possible relationship with chaperones, golgins and already known autoantigens like GAD67. Reactivity against MPA indicates that these proteins certainly play a role in the processes undergoing within pituitary of CPHD patients. The identification and further detailed studies on their role in the pathogenesis of CPHD should be continued.

Diffuse thyroid uptake incidentally found on 18F-fluorodeoxyglucose positron emission tomography in subjects without cancer history.

OBJECTIVE: We investigated the clinical significance of incidental diffuse thyroid uptake (DTU) on (18)F-FDG PET in subjects without a history of cancer. MATERIALS AND METHODS: This study included 2062 studies from adults who underwent (18)F-FDG PET as a cancer screening program. Subjects were divided into the following two groups: with (group I) or without (group II) DTU. The presence of DTU and the thyroid visual grading score were compared with thyroid function tests, serum anti-microsomal antibody (AMA) levels, and the presence of diffuse parenchymal change (DPC) on ultrasonography (USG). RESULTS: DTU was found in 6.6% of the scans (137/2062). Serum thyroid stimulating hormone (TSH) and AMA levels were significantly higher in group I than in group II. Increased AMA level (55.1%) and DPC (48.7%) were more frequently found in group I (p < 0.001). The proportion of subjects with any abnormal results in serum free thyroxine, triiodothyronine, TSH, or AMA levels or DPC on USG was significantly higher in group I than in group II (71.5% vs. 10.6%, p < 0.001), and was significantly and gradually increased according to the visual grading score group (0 vs. 1-2 vs. 3-4 = 10.6% vs. 58.5% vs. 90.9%, p < 0.001). TSH and is AMA levels were significantly increased according to the visual grading score. CONCLUSION: The presence or degree of incidental DTU on (18)F-FDG PET is closely correlated with increased serum AMA and TSH levels, and the presence of DPC on USG. Therefore, the most plausible pathological cause of DTU may be cell damage by an autoimmune mechanism.

Mechanisms of induction of cytosolic and microsomal glutathione transferase (GST) genes by xenobiotics and pro-inflammatory agents.

Glutathione transferase (GST) isoezymes are encoded by three separate families of genes (designated cytosolic, microsomal and mitochondrial transferases), with distinct evolutionary origins, that provide mammalian species with protection against electrophiles and oxidative stressors in the environment. Members of the cytosolic class Alpha, Mu, Pi and Theta GST, and also certain microsomal transferases (MGST2 and MGST3), are up-regulated by a diverse spectrum of foreign compounds typified by phenobarbital, 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene, pregnenolone-16α-carbonitrile, 3-methylcholanthrene, 2,3,7,8-tetrachloro-dibenzo-p-dioxin, ß-naphthoflavone, butylated hydroxyanisole, ethoxyquin, oltipraz, fumaric acid, sulforaphane, coumarin, 1-[2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oyl]imidazole, 12-O-tetradecanoylphorbol-13-acetate, dexamethasone and thiazolidinediones. Collectively, these compounds induce gene expression through the constitutive androstane receptor (CAR), the pregnane X receptor (PXR), the aryl hydrocarbon receptor (AhR), NF-E2-related factor 2 (Nrf2), peroxisome proliferator-activated receptor-γ (PPARγ) and CAATT/enhancer binding protein (C/EBP) ß. The microsomal T family includes 5-lipoxygenase activating protein (FLAP), leukotriene C(4) synthase (LTC4S) and prostaglandin E(2) synthase (PGES-1), and these are up-regulated by tumour necrosis factor-α, lipopolysaccharide and transforming growth factor-ß. Induction of genes encoding FLAP, LTC4S and PGES-1 is mediated by the transcription factors C/EBPα, C/EBPδ, C/EBPϵ, nuclear factor-κB and early growth response-1. In this article we have reviewed the literature describing the mechanisms by which cytosolic and microsomal GST are up-regulated by xenobiotics, drugs, cytokines and endotoxin. We discuss cross-talk between the different induction mechanisms, and have employed bioinformatics to identify cis-elements in the upstream regions of GST genes to which the various transcription factors mentioned above may be recruited.

Clinical and pathological features of Riedel's thyroiditis.

OBJECTIVE: To evaluate the clinical and pathological features of Riedel's thyroiditis (RT), and current diagnostic and treatment methods for that disease. METHODS: Five RT cases identified by surgery and pathological examinations at Peking Union Medical College Hospital from 1985 to 2009 were analyzed and compared with the cases reported in the literature in terms of clinical and pathological features. Immunohistochemical staining of kappa and lambda light chains was carried out for RT tissues from all the five patients. RESULTS: All the five cases were females, aged 45-55 years. Elevation of serum thyroid autoantibodies was found in only one patient, who had longer disease duration than the others. Pathological examination revealed invasive fibrosclerosis of the thyroid follicles, thyroid capsule, and the surrounding tissues. In RT tissues, the number of cells containing lambda chains was a little higher than those containing kappa chains. CONCLUSIONS: RT is a rare disease which might be more common in middle-aged females than in other populations. Pathological features include the destruction of thyroid follicle, extension into surrounding tissues by inflammatory cells and fibrous tissues. Immunohistochemical staining of kappa and lambda chains could help diagnose RT.

Features of papillary thyroid microcarcinoma in the presence and absence of lymphocytic thyroiditis.

It is known that the prevalence of lymphocytic thyroiditis (LT) is higher in patients with papillary thyroid carcinoma (PTC), that gender influences this association, and that certain features of PTC occur more frequently in patients who also have LT. These relationships have not been studied in patients with papillary thyroid microcarcinomas (PTMC), however. Therefore, we performed a study to compare the clinical and pathological features of patients with PTMC who did and did not have LT. We collected the 323 consecutive patients following excision of PTMC diagnosed as papillary carcinoma on preoperative needle aspiration cytology. We analyzed the demographic, serologic, and pathologic data of those cases with categorization into four groups based on presence of LT and neck lymph node metastasis. In all PTMC, the presence of LT did not influence the frequency of lymph node metastasis (27 of 105 [25.7%] vs. 48 of 218 [22.0%]). Among the patients with metastatic PTMC, LT was noted significantly more often in female than male patients (95.2% vs. 79.8%). In metastatic PTMC, multifocality and bilaterality was more frequent in with LT than without LT (44.4% vs. 29.2%; 29.6% vs. 14.6%). Both the presence of serum thyroglobulin antibody (TgAb; p = 0.016) and serum microsomal antibody (p = 0.013) were highly correlated with the presence of LT. Twenty-seven of 105 patients (25.7%) with PTMC with LT had nodal metastasis. Co-existing LT was noted predominantly in women, influenced more often multifocality and bilaterality of tumors, and higher frequency of metastasis to lateral compartment lymph nodes.

Prevalência de anticorpos antimicrossomais em pacientes com esclerose múltipla / Prevalence of antimicrosomal antibodies in patients with multiple sclerosis

O objetivo deste estudo consiste em avaliar a prevalência de anticorpos antimicrossomais (AAM), a função tireóidea e a ocorrência de sintomas relacionados ao hipotireoidismo em pacientes com esclerose multipla (EM). Em um grupo de 21 pacientes com EM, foi realizado exameclínico, foram dosados o TSH, T4 e T4 livre e pesquisados AAM. A média de idade foi 41,05 anos e a média de tempo de doença foi 85,9 meses. Os sintomas relacionados ao hipotireoidismo foram fadiga, fraqueza, letargia e parestesias. Os AAM foram encontrados em 4 pacientes (19 por cento). O tempo de doença foi dividido em três períodos: <60 meses (3 pacientes AAM+/7AAM-), 60-120 meses (8 pacientes AAM-) e >120 meses (1 paciente AAM+/2 AAM-). Dois pacientes apresentaram níveis de T4 livre diminuídos, porém com T4 e TSH normais. Em 1 paciente, constatou-se hipotireoidismo subclínico, e em outro, hipotireoidismo clássico. Conclui-se que na avaliação dos pacientes com EM, em vista da falta de precisão na avaliação clínica do hipotireoidismo ocasionada pela sobreposição de sintomas referentes à EM, devam ser incorporadas as dosagens das provas de função tireóidea (PFT) e dos AAM.

[Prevalence of antimicrosomal antibodies in patients with multiple sclerosis]. / Prevalência de anticorpos antimicrossomais em pacientes com esclerose múltipla.

The aim of this study was to assess the prevalence of Antimicrosomal Antibodies AMA, thyroid function and the occurrence of hypothyroidism symptoms in patients with Multiple Sclerosis (MS). Clinical examination was carried out in 21 MS patients; thyroid-stimulating hormone (TSH), thyroxine (T4), free T4 and AMA were measured. Mean age was 41.05 years. Hypothyroidism symptoms included fatigue, weakness, lethargy and paresthesia. AMA were found in four patients (19%). Three categories of disease duration were considered: <60 months (3 patients AMA+; 7 AMA-), 60-120 months (8 patients AMA-), and >120 months (1 patient AMA+; 2 AMA-). Two patients presented decreased free T4 levels, but there was no associated decrease in T4 and TSH levels. In two patients, a mild increase in TSH levels was observed: one presented normal T4 levels (subclinical hypothyroidism) and the other one had low free T4 levels (classical hypothyroidism). We conclude that AMA measurement and thyroid function tests should become part of the routine assessment of MS patients, in view of the inaccuracy currently observed in the assessment of clinical hypothyroidism as a result of the superposition of hypothyroidism and MS signs and symptoms.

Production of monoclonal antibodies against peripheral-vesicle proteins in zoospores of Phytophthora nicotianae.

A coimmunisation protocol using microsomal fractions from Phytophthora nicotianae cells has enhanced the production of monoclonal antibodies directed towards proteins produced during asexual sporulation. Over 40% of the antibodies targeted three categories of zoospore peripheral vesicles. Five antibodies label the contents of dorsal vesicles, with three of these reacting with two P. nicotianae polypeptides with a relative molecular mass of approximately 100 kDa. Two antibodies label the contents of large peripheral vesicles and react with two very high-molecular-weight polypeptides in extracts of P. nicotianae cells. These antibodies cross-react with the contents of large peripheral vesicles in P. cinnamomi zoospores. Ten antibodies label the contents of P. nicotianae zoospore ventral vesicles and react with a single polypeptide with a relative molecular mass of 230 kDa. A number of these antibodies against the contents of ventral vesicles in P. nicotianae zoospores cross-react with ventral-vesicle proteins in P. cinnamomi cells in immunofluorescence and immunoblot assays. The study illustrates the value of the coimmunisation protocol and has produced antibodies that could be instrumental in the cloning of genes encoding peripheral-vesicle proteins.

Retrotranslocation of MHC class I heavy chain from the endoplasmic reticulum to the cytosol is dependent on ATP supply to the ER lumen.

MHC class I heavy chains (HC) that fail to acquire a mature conformation in the endoplasmic reticulum (ER) as a result of defective folding or assembly with beta2-microglobulin, or lack of appropriate peptide cargo are retrotranslocated through the Sec61 channel to the cytosol for degradation by proteasomes. The mechanisms involved in ER retrotranslocation of HC are as yet incompletely understood. Using a microsomal system, we characterized the molecular requirements for the release of HC into the soluble fraction. Extraction of ubiquitinated HC was facilitated by cytosol, or by addition of proteins that stabilized the membrane association of the cytoplasmic ATPase p97. Functional proteasomes were not needed for HC mobilization. ATP supply to the ER lumen was found to be an essential factor since an inhibitor of the ATP importing pump in the ER membrane blocked HC release. Also non-hydrolyzable ATP analogs delivered to the ER lumen facilitated HC export suggesting that ATP binding by ER chaperones rather than ATP hydrolysis is involved.

Long-term follow-up of myasthenia gravis patients with hyperthyroidism.

OBJECTIVE: To access clinical characteristics and treatment outcome of myasthenia gravis (MG) patients with hyperthyroidism (HT). MATERIALS AND METHODS: The clinical characteristics of 51 MG patients with HT were studied. The treatment outcome was analysed in 34 patients, comparing high-dosage prednisolone (HDP) (group IS), HDP and/or immunosuppressants with antithyroid drugs (group IS + antiHThyr), antithyroid drugs (group antiHThyr), and thymectomy. RESULTS: The prevalence of HT in MG was 17.5%. Group IS showed higher remission of both diseases compared with group antiHThyr, but not with group IS + antiHThyr. Remission of HT and relapse of both diseases showed no difference among the three groups. Ten patients who had thymectomies had a lower relapse of MG but not of HT, whilst remission of both diseases was no different to 24 non-thymectomy patients. CONCLUSION: This study showed a high prevalence of HT in Thai MG. HDP alone can induce remission of both diseases without difference in relapse. Thymectomy lowers MG relapse further but has no influence on HT.

Membrane-specific, host-derived factors are required for US2- and US11-mediated degradation of major histocompatibility complex class I molecules.

Human cytomegalovirus encodes two glycoproteins, US2 and US11, that target major histocompatibility complex (MHC) class I heavy chains for proteasomal degradation. We have developed a mRNA-dependent cell-free system that recapitulates US2- and US11-mediated degradation of MHC class I heavy chains. Microsomes support the degradation of MHC class I heavy chains in the presence of US2 or US11 in a cytosol-dependent manner. In vitro, the glycosylated heavy chain is exported from the microsomes. A deglycosylated breakdown intermediate of the heavy chain identical to that generated in intact cells accumulates in soluble form in the presence of proteasome inhibitors. Microsomes derived from the U373 astrocytoma cell line are far more effective than canine-derived membranes in supporting this US2- or US11-dependent reaction. In contrast, the HIV-encoded Vpu membrane protein can cause the destruction of CD4 from either human- or canine-derived membranes. Using the in vitro system, we show that a truncation mutant of US2 that lacks the cytosolic domain is unable to catalyze degradation, whereas a similar truncation of US11 continues to catalyze degradation of class I heavy chains. Therefore, US2 requires both transmembrane and cytosolic interactions to trigger dislocation of heavy chains, whereas US11 relies on the transmembrane domain to target heavy chains. US2 and US11 thus utilize different targeting mechanisms for class I degradation.

Identification and characterization of nuclear CD38 in the rat spleen.

CD38 is an ectoenzyme, which can produce metabolites with intracellular Ca(2+) mobilizing properties and has multiple immunological functions. However, we have recently shown that CD38 is also localized to the nucleus of rat hepatocyte whereby its metabolite cADPR, is able to mobilize nuclear Ca(2+) stores. In this study, we further characterize the localization of nuclear CD38 in the spleen, an important immune organ. We managed to detect the presence of ADP-ribosyl cyclase activity in the nuclear fraction. With Western blotting, we managed to characterize a 42-45 kDa protein band that is typical of CD38 under reducing and non-reducing conditions. However, as a comparison, other nuclear fractions from tissues like thymus, cardiac muscle and cerebellum yielded an additional 85 kDa protein band under non-reducing conditions. Both protein bands could be blocked with a CD38 blocking peptide. Immunohistochemical studies revealed the expression of CD38 in the marginal zone and in the red pulp. In contrast, the germinal center remained largely immunonegative for CD38. This is the first report of a functionally active ADP-ribosyl cyclase/CD38 in the spleen nuclear fraction. The results here suggest that the presence of CD38 in the nuclear environment might have a corollary to functional and regulatory roles in the nucleus.

Effect of treatment of hypothyroidism on the plasma concentrations of neuroactive steroids and homocysteine.

Autoimmune thyroiditis with hypothyroidism is frequently accompanied by symptoms of psychiatric disorders and atherogenic changes in lipid metabolism. Recent studies suggest that some neuroactive steroids and homocysteine are involved in the pathophysiology of both disorders. Homocysteine metabolism may be affected by some steroids. We were interested if the treatment of hypothyroidism would affect the above factors. We studied plasma concentrations of allopregnanolone, pregnenolone sulfate, dehydroepiandosterone and its sulfate, progesterone, estradiol and homocysteine in 14 patients (12 women, 2 men) during the 3-month treatment with levothyroxine. Steroids and thyroid function were monitored by measuring thyrotropin, free triiodothyronine, free thyroxine and levels of thyroid antimicrosomal antibodies and antibodies to thyroglobulin. We have found that with the restoration of the thyrotropin level, free triiodothyronine, free thyroxine and homocysteine levels decreased, but the levels of steroids were not significantly altered. Steroid concentrations correlated negatively with the level of thyroid antimicrosomal antibodies.