Congenital tuberculosis in an extremely preterm infant and prevention of nosocomial infection

Congenital tuberculosis is a rare disease, especially in non-endemic countries. We present a preterm infant who developed congenital tuberculosis in a neonatal intensive care unit (NICU). The male patient, weighing 1140 g was born by cesarean section at 26 weeks gestation. The baby's respiratory condition suddenly deteriorated at 18 days old, and he was diagnosed with congenital tuberculosis after Gram stain revealed “ghost bacilli” in his tracheal aspirate. The mother, who was born in an endemic country, had fever with unknown cause during labor and was diagnosed with miliary tuberculosis after the infant was diagnosed. Both were successfully treated for tuberculosis with a four-drug regimen. The genotyping profiles of Mycobacterium tuberculosis were identical in both mother and baby based on variable number of tandem repeat (VNTR) analysis. The lineage was considered to be East-African Indian. To prevent nosocomial infection in the NICU, 23 potentially exposed infants received isoniazid for 2 months. Two infants showed a transient liver enzyme elevation that seemed to be due to isoniazid. For 10 months after the incident, there were no infants and medical staff who developed tuberculosis. Although the incidence of tuberculosis has steadily decreased in Japan, the percentage of foreign-born individuals has increased yearly, especially those of reproductive age. The evaluation of active tuberculosis should be considered in pregnant women with unexplained fever, history of tuberculosis, or emigration from high-burden areas.     

Designing the epitope flanking regions for optimal generation of CTL epitopes

The flanking amino acids that surround epitopes are critical for effective antigen processing and maintenance of epitope integrity. In the present study, the frequency and characteristics of each amino acid that flanked the peptides generated from the proteasomal degradation of three different subtypes of HIV-1 Gag-p24 were determined. Synthetic flanking regions were designed based on the highest and the lowest frequencies of amino acid with the ideal characteristics at positions upstream and downstream of the proteasomal cleavage site. Peptides were synthesized that contained known CD8+ CTL-epitopes from HIV-1 Gag, CMV pp65, and vaccinia proteins HRP-2, and C16, flanked by amino acid sequences specifically designed to either generate or inhibit the known CD8+ CTL-epitopes. As predicted, the known CD8+ CTL-epitopes were effectively generated from the peptides with synthetic flanking regions specifically designed to promote epitope generation in a proteasome-dependent manner. The majority of the proteasome-generated epitopes were cleaved immediately after the C-terminal amino acid of the specific CTL-epitope. The synthetic peptide sequences containing known CD8+ CTL-epitopes with the flanking regions that promote epitope generation were effectively processed and presented to epitope specific CD8+ T-cells resulting in the production of IFN-γ. These results highlight the importance of flanking regions in promoting efficient antigen processing and presentation. This concept can have important implications in vaccine design and development strategies.     

小干扰RNA抑制成熟树突细胞表面抗原CD80/CD86的表达

背景：成熟树突细胞可通过其表面抗原CD80/CD86来启动Th细胞活化,促使Th细胞向Th1细胞分化减少、向Th2细胞方向分化增多。〈br〉 目的：探讨小干扰RNA抑制哮喘小鼠成熟树突细胞表面抗原CD80/CD86表达后对Th1及Th2型细胞因子干扰素γ、白细胞介素4分泌的影响。方法：建立哮喘小鼠模型,分离哮喘小鼠骨髓成熟树突细胞,流式细胞术检测表面标记物 CD11c、CD80、CD86的阳性表达率;设计合成CD80/CD86相关小干扰RNA转染哮喘小鼠成熟树突细胞,荧光定量PCR、流式细胞术检测干扰前后成熟树突细胞中CD80/CD86 mRNA和相应蛋白的表达,将干扰组、未干扰组、转染试剂对照组的成熟树突细胞分别与小鼠T淋巴细胞共培养,ELISA检测上清液中Th1及Th2型细胞因子干扰素γ、白细胞介素4分泌水平。结果与结论：①正常组成熟树突细胞的CD80/CD86的表达与哮喘组相比均明显降低（均P＜0.05）。②小干扰RNA转染哮喘小鼠成熟树突细胞后,干扰组CD80/CD86 mRNA及其蛋白表达水平较其他组均明显降低（均P＜0.05）。③小干扰RNA转染后干扰组共培养体系中干扰素γ水平明显高于其他组（均P＜0.05）,白细胞介素4水平则明显低于其他组（均P ＜0.05）。提示哮喘小鼠成熟树突细胞高表达CD80/CD86,小干扰RNA特异性抑制哮喘小鼠成熟树突细胞中CD80/CD86的表达,能增加干扰素γ并减少白细胞介素4的分泌,从而纠正Th1/Th2失衡。     

Increased IL-2, IL-4 and interferon-gamma (IFN-gamma) in steroid-sensitive nephrotic syndrome.

We investigated the production of cytokines by peripheral blood mononuclear cells (PBMC) and serum cytokine concentrations in children with steroid-sensitive idiopathic nephrotic syndrome (SSNS). PBMC from patients off treatment were collected during remission and relapse and cultured in medium alone or stimulated with calcium ionophore plus phorbol myristate acetate. Control PBMC were taken from healthy age-matched children. IL-2 was measured by bioassay, IL-4 by immunoradiometric assay, and IL-8 and IFN-gamma by ELISA. After 24 h culture without stimulation, IL-2, IL-4 and IFN-gamma were not detectable in the supernatant in any of the children. After stimulation, the supernatant concentrations of IL-2 (median 172 U/ml at 24 h) and IL-4 (160 pg/ml at 24 h; 210 pg/ml at 72 h) were significantly increased in relapse compared with remission (IL-2 37 U/ml; IL-4 65 pg/ml and 60 pg/ml) and controls (IL-2 69 U/ml; IL-4 40 pg/ml and 40 pg/ml) (P < 0.05). The concentration of IFN-gamma was not significantly increased in relapse compared with remission and controls (600, 325, and 145 U/ml, respectively, at 72 h). IL-8 concentrations were similar in relapse, remission and controls with stimulation (median 32, 40 and 40 ng/ml, respectively) and without (30, 17 and 10 ng/ml). IL-2 was not detectable in serum, but IL-4, IL-8 and IFN-gamma were measurable in about half the patients, both in relapse and remission, though were virtually undetectable in controls. We conclude that relapse of SSNS in children is associated with T lymphocyte activation with release of IL-2, IL-4 and IFN-gamma.     

Modulation of the cellular immune response during Plasmodium falciparum infections in sickle cell trait individuals.

Plasma and peripheral blood mononuclear cells (PBMC) were obtained from P. falciparum-infected individuals with and without the sickle cell trait at diagnosis and 7 days after treatment. HbAA and HbAS patients were compared for levels of plasma soluble IL-2 receptors (IL-2R) and the in vitro cellular reactivity to affinity-purified soluble P. falciparum antigens (SPAg), PPD and phytohaemagglutinin (PHA). At diagnosis, HbAS patients with clinical disease had lower plasma-soluble IL-2R levels and parasite counts than the corresponding HbAA patients, whereas HbAS and HbAA patients with asymptomatic infections had comparable soluble IL-2R levels and parasite counts. PBMC from HbAS patients had higher proliferation and IFN-gamma production in response to SPAg than PBMC from HbAA patients. The difference in the lymphoproliferative responses to SPAg between the two groups was evident in patients with asymptomatic infections. In all patients, the clinical severity, the soluble IL-2R levels and the parasite counts were directly related. The former two were inversely related to the proliferative responses to SPAg. After treatment, all the studied parameters were comparable in the two groups. The study indicates that during P. falciparum infection, HbAS compared with HbAA patients had lower in vivo cellular activation and higher in vitro cellular reactivity in response to soluble malaria antigens.     

Increased levels of interferon-gamma (IFN-gamma), IL-4 and transforming growth factor-beta (TGF-beta) mRNA expressing blood mononuclear cells in human HIV infection.

Evidence has been presented for the involvement of IFN-gamma, IL-4 and TGF-beta in AIDS. Measured plasma levels may, however, poorly reflect in vivo production, since cytokines act auto- and paracrinally and have very short half life in plasma. In situ hybridization with complementary DNA oligonucleotide probes was used to enumerate blood mononuclear cells expressing cytokine messenger RNA (mRNA). HIV-infected patients had elevated blood levels of cells expressing each of the cytokines, with predominance for cells expressing TGF-beta mRNA. All AIDS patients included had elevated numbers of IL-4 mRNA-expressing cells, and levels of cells expressing this cytokine correlated inversely with counts of CD4+ cells in blood, reflecting the involvement of Th2-like cells in later stages of HIV infection. The described approach should be useful in further studies of cytokines in HIV infection and other diseases.     

Regulation of C3 and factor H synthesis of human glomerular mesangial cells by IL-1 and interferon-gamma.

Previous reports have shown production of complement components C4, C2 and factor B by renal tissue. We have shown recently that human proximal tubular epithelial cells (PTEC) synthesize C3 in vitro, and that IL-2 enhances this production. In the present study we demonstrate that human mesangial cells (MC) in culture produce factor H and that supernatants of activated peripheral blood mononuclear cells (T cell growth factor (TCGF)) induce C3 production and enhance factor H synthesis in both a time- and dose-dependent manner. To investigate whether certain defined cytokines from TCGF were responsible for the observed effect, we tested various cytokines for their effect on complement production by MC. It is shown that IL-1 induces C3 synthesis whereas factor H production is up-regulated by IFN-gamma, in both a dose- and time-dependent manner. Antibody blocking experiments revealed that C3 synthesis induced by both TCGF and IL-1 could be blocked with antibodies specific for IL-1, and also that TCGF and IFN-gamma enhanced factor H synthesis could both be blocked with antibodies specific for IFN-gamma. Cycloheximide was able to inhibit C3 and factor H production, suggesting de novo synthesis of the proteins. mRNA-polymerase chain reaction (PCR) analysis revealed mRNA encoding for C3 after stimulation with TCGF and IL-1. Factor H genes are constitutively expressed in cultured mesangial cells and its expression is up-regulated by TCGF and IFN-gamma. Northern blot analysis with specific probes for C3 and factor H revealed bands which support the results obtained by PCR analysis.     

Apoptosis of colorectal adenocarcinoma (COLO 201) by tumour necrosis factor-alpha (TNF-α) and/or interferon-gamma (IFN-γ), resulting from down-modulation of Bcl-2 expression

Fas antigen is constitutively expressed in the normal colon epithelium, but considerably diminished in most colorectal carcinomas. In the present study, we examine the relationship between Fas antigen expression and apoptosis using the colorectal carcinoma cell line COLO 201, on which a low grade of Fas antigen is expressed. Anti-Fas antibody had no effect on the induction of apoptosis of COLO 201. However, TNF-α and/or IFN-γ, independently and additively, up-regulated Fas antigen expression on COLO 201 and induced apoptosis in a dose-dependent manner. Both cytokines also increased the COLO 201 sensitivity to anti-Fas antibody, resulting from the down-modulation of Bcl-2 and the up-regulation of Bax. These findings indicate that cytokine(s) plus anti-Fas antibody (which mimics natural Fas ligand) are more effective in inducing apoptosis of COLO 201 than cytokine(s) alone. These findings suggest that immunotherapy in combination with cytokine(s) and lymphokine-activated killer (LAK) cells will become a more effective therapy for cancer than cytokine(s) or LAK cells alone, since the Fas ligand is expressed on activated T cells, natural killer cells and macrophages.