Reduced ratio of protective versus proinflammatory cytokine responses to commensal bacteria in HLA-B27 transgenic rats

Germ-free HLA-B27 transgenic (TG) rats do not develop colitis, but colonization with specific pathogen-free (SPF) bacteria induces colitis accompanied by immune activation. To study host-dependent immune responses to commensal caecal bacteria we investigated cytokine profiles in mesenteric lymph node (MLN) cells from HLA-B27 TG versus nontransgenic (non-TG) littermates after in vitro stimulation with caecal bacterial lysates (CBL). Supernatants from CBL-stimulated unseparated T- or B- cell-depleted MLN cells from HLA-B27 TG and non-TG littermates were analysed for IFN-gamma, IL-12, TNF, IL-10 and TGF-beta production. Our results show that unfractionated TG MLN cells stimulated with CBL produced more IFN-gamma, IL-12 and TNF than did non-TG MLN cells. In contrast, CBL-stimulated non-TG MLN cells produced more IL-10 and TGF-beta. T cell depletion abolished IFN-gamma and decreased IL-12 production, but did not affect IL-10 and TGF-beta production. Conversely, neither IL-10 nor TGF-beta was produced in cultures of B cell-depleted MLN. In addition, CD4(+) T cells enriched from MLN of HLA-B27 TG but not from non-TG rats produced IFN-gamma when cocultured with CBL-pulsed antigen presenting cells from non-TG rats. Interestingly, IL-10 and TGF-beta, but not IFN-gamma, IL-12 and TNF were produced by MLN cells from germ-free TG rats. These results indicate that the colitis that develops in SPF HLA-B27 TG rats is accompanied by activation of IFN-gamma-producing CD4(+) T cells that respond to commensal bacteria. However, B cell cytokine production in response to components of commensal intestinal microorganisms occurs in the absence of intestinal inflammation.     

Determinants of CD4 Counts Among HIV-Negative Ethiopians: Role of Body Mass Index,Gender, Cigarette Smoking,Khat (<Emphasis Type="Italic">Catha Edulis</Emphasis>) Chewing,and Possibly Altitude?

To study the determinants of CD4% and CD4 counts among HIV-negative Ethiopians, and to identify factors susceptible to explain the low CD4 counts observed among Ethiopian subjects. Cohort studies among factory workers in Akaki and Wonji, Ethiopia. Clinical and laboratory examinations, including determination of HIV serological status and T-cell subsets, were performed during follow-up visits every six months. In addition, micronutrients (retinol, carotenoids, tocopherol, transferrin receptor, and selenium) plasma concentrations were determined in a subset of 38 HIV-positive and 121 HIV-negative participants. HIV-negative participants with at least one CD4 count measurement were 157 females in Akaki, 203 males in Akaki, and 712 males in Wonji. CD4 counts were independently and positively associated with body mass index (through an increase in lymphocyte counts), female gender (through an increase in CD4%), cigarette smoking (through an increase in CD4%), khat chewing (through an increase in both lymphocyte counts and CD4%), and Akaki study site (through a large increase in lymphocyte counts compensating a decrease in CD4%). Intestinal parasitic infections were not associated with CD4% or CD4 counts. Retinol, carotenoids, and -tocopherol plasma concentrations decreased with HIV infection and advancing immunosuppression, but were not associated with CD4 counts among HIV-negative subjects. Low body mass index among Ethiopians may have contributed to their overall low CD4 counts. Other factors remain to be elucidated.     

Ligand and cytokine dependence of the immunosuppressive pathway of tryptophan catabolism in plasmacytoid dendritic cells

Murine plasmacytoid dendritic cells (pDCs) have been credited with a unique ability to express indoleamine 2,3-dioxygenase (IDO) function and mediate immunosuppression in specific settings; yet, the conditions of spontaneous versus induced activity have remained unclear. We have used maneuvers known to up-regulate IDO in different cell types and have examined the relative efficacy and mechanisms of the induced activity in splenic pDCs, namely, after specific receptor engagement by CTLA-4-Ig, CD200-Ig or CD28-Ig, the latter in combination with silenced expression of the suppressor of cytokine signaling 3 (SOCS3) gene. We found that pDCs (CD11c+ mPDCA-1+ 120G8+) do not express IDO and are not tolerogenic under basal conditions. B7-1 engagement by CTLA-4-Ig, CD200R1 engagement by CD200-Ig and B7-1/B7-2 engagement by CD28-Ig in SOCS3-deficient pDCs were each capable of initiating IDO-dependent tolerance via different mechanisms. IFN-gamma was the major cytokine responsible for CTLA-4-Ig effects, and type I IFNs for those of CD200-Ig. Immunosuppression by CD28-Ig in the absence of SOCS3 required IFN-gamma induction and IFN-like actions of IL-6. Therefore, although pDCs do not mediate IDO-dependent tolerance constitutively, multiple ligands and cytokines will contribute to the expression of a tolerogenic phenotype by pDCs in the mouse.     

CD1d deficiency exacerbates inflammatory dermatitis in MRL-lpr/lpr mice

Mechanisms responsible for the development of autoimmune skin disease in humans and animal models with lupus remain poorly understood. In this study, we have investigated the role of CD1d, an antigen-presenting molecule known to activate natural killer T cells, in the development of inflammatory dermatitis in lupus-susceptible MRL-lpr/lpr mice. In particular, we have established MRL-lpr/lpr mice carrying a germ-line deletion of the CD1d genes. We demonstrate that CD1d-deficient MRL-lpr/lpr mice, as compared with wild-type littermates, have more frequent and more severe skin disease, with increased local infiltration with mast cells, lymphocytes and dendritic cells, including Langerhans cells. CD1d-deficient MRL-lpr/lpr mice had increased prevalence of CD4(+) T cells in the spleen and liver and of TCR alpha beta (+)B220(+) cells in lymph nodes. Furthermore, CD1d deficiency was associated with decreased T cell production of type 2 cytokines and increased or unchanged type 1 cytokines. These findings indicate a regulatory role of CD1d in inflammatory dermatitis. Understanding the mechanisms by which CD1d deficiency results in splenic T cell expansion and cytokine alterations, with increased dermal infiltration of dendritic cells and lymphocytes in MRL-lpr/lpr mice, will have implications for the pathogenesis of inflammatory skin diseases.     

The common heat shock protein receptor CD91 is up-regulated on monocytes of advanced melanoma slow progressors

Despite advances in our understanding of tumour immunology there is no therapy of proven survival benefit for advanced melanoma. Nevertheless, disease progression is slow in a small proportion of patients with metastatic melanoma, suggesting a contribution to outcome from host factors. Recent data have indicated the importance of the heat shock protein receptor CD91 in immune responses to, and progression of, infectious disease. Here we investigate the relationship between CD91 expression and outcome in malignancy. Rare melanoma patients were recruited with advanced disease that was progressing unusually slowly. CD91 expression on their monocytes was compared with control patients with more typical rapidly advancing metastatic disease. Th1 and Th2 cytokines, as well as innate and adaptive immune subsets, were also measured in the two groups. A significant increase in median CD91 expression levels was observed in slow progressors (P = 0.006). There were no differences in other immune subset markers or inflammatory cytokines. The ability of CD91 to internalize and cross-present tumour antigens through the major histocompatibility complex class I pathway may maintain CD8-positive cytotoxic T cell responses and contribute to slow progression of advanced melanoma.     

Dissecting the complexity of the memory T cell response

Memory immune responses are classically attributed to the reactivation of long-lived, antigen-specific T lymphocytes that persist in a quiescent state. Determining mechanisms for the generation of memory T cells and dissecting the functional nature of the memory T cell pool has been encumbered by an inability to distinguish recently activated effector T cells from memory T cells. We have established new activation and biochemical criteria that distinguish effector and memory T cells and have applied these criteria to follow memory generation from activated cells in vivo. We found that the resultant memory T cell pool is heterogeneous and consists of effector-like and resting memory-like subsets that differ in expression of the homing receptor, CD62L. We discuss these findings in the context of memory T cell heterogeneity identified in human and mouse systems. These results suggest that more than one type of previously activated T cell can mediate recall or memory immune responses and that elucidating the fundamental phenotypic and functional features of memory T cell subsets is therefore critical to deciphering the complex nature of the memory immune response.     

MS患者CD94/NKG2A-bright和CD94/NKG2A-dim NK细胞亚群对IFN-β的差异性反应

目的： 分析多发性硬化（MS）进展型患者不同表型NK细胞亚群对临床主要治疗方法的反应性差异.方法： 分离患者外周血中的NK细胞, 以流式细胞术根据表面抑制性受体CD94/NKG2A表达情况分为两个亚群CD94/NKG2A-bright和CD94/NKG2A-dim.分别加入IFN-β, 测定两个亚群表面CD94/NKG2A变化及细胞增殖, 同时检测两种亚群分泌IL-10和TGF-β情况.结果： CD94/NKG2A阳性表达的NK细胞占25.5%, 其中CD94/NKG2A-bright和CD94/NKG2A-dim分别占其中的23.6%和76.4%.加入IFN-β, CD94/NKG2A-bright组增殖率明显低于CD94/NKG2A-dim组, CD94/NKG2A表达峰度变化不大.CD94/NKG2A-dim组中CD94/NKG2A表达显著增加.两个亚群分泌的IL-10和TGF-β与未刺激组相比, 均有明显差异.CD94/NKG2A-bright和CD94/NKG2A-dim组间亦有明显差异.结论： IFN-β通过诱导NK细胞CD94/NKG2A表达在非特异免疫系统中抑制NK细胞; 同时刺激IL-10 和TGF-β分泌进一步发挥对免疫系统的抑制.CD94/NKG2A-bright和CD94/NKG2A-dim对IFN-β反应有差异性.     

小鼠脑微血管内皮细胞株bEnd.3的细胞特征及基因表达谱分析

目的:对一种小鼠脑组织来源的血管内皮细胞株bEnd.3的主要细胞特征进行研究并做血管内皮细胞生物学功能基因芯片分析。方法:利用倒置显微镜、扫描和透射电子显微镜观察细胞形态特征;免疫细胞化学法显示血管内皮细胞特异性表面标志;ELISA定量检测PGE₂;流式细胞术、MTT法研究增殖和凋亡、血管内皮细胞基因芯片研究正常培养bEnd.3基因表达谱。结果:bEnd.3具备多种典型的微血管内皮细胞(MVEC)特征:细胞呈多边形或梭型、呈铺路石样生长;存在管腔样结构(TLS)和毛细血管样网络,细胞表面有丰富的微绒毛;vW因子、CD34阳性;CD31、CD36、CD105等也有不同程度的表达;细胞高水平分泌前列腺素E₂(PGE₂);多种与正常血管功能密切相关的基因也有不同程度的表达。结论:bEnd.3保留了MVEC的基本特性,可用于心脑血管疾病、肿瘤等重大疾病的发病机制的基础与临床研究。     

宫颈鳞癌PCNA及间质内CD34表达的临床意义

宫颈鳞状细胞癌是女性常见的恶性肿瘤，研究其发生过程、发病机制有着重要意义。宫颈鳞癌细胞的增殖活性及其对间质内微血管的依赖情况，可通过测定PCNA及CD34来了解。笔者应用免疫组织化学方法对139例子宫颈鳞癌进行PCNA、CD34检测，观察其在不同临床分期、不同病理分级的表达并探讨其临床意义。     

Evaluation of the Effect of β-Endorphin on IL-4 and γ-IFN Production by CD4<Superscript>+</Superscript> Lymphocytes

β-Endorphin stimulates phytohemagglutinin-induced production of IL-4 and does not modify the production of γ-IFN in nonfractionated leukocyte suspension. In a culture of purified CD4⁺ T-cells, β-endorphin does not modify the levels of IL-4 and γ-IFN, but stimulates the production of IL-4 and inhibits γ-IFN production after addition of monocytes to CD4⁺ lymphocytes. Stimulation of IL-4 synthesis by β-endorphin is mediated by the cycloxygenase cycle products. Hence, β-endorphin shifts T-helper polarization towards Th2 cells with subsequent predominance of the humoral form of the immune response. Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 146, No. 10, pp. 427-430, October, 2008