Adiponectin inhibits oxidization-induced differentiation of T helper cells through inhibiting costimulatory CD40 and CD80

Adiponectin is a multifunctional adipokine that has several oligomeric forms in the blood stream, which broadly regulates innate and acquired immunity. Therefore, in this study, we aimed to observe the differentiation of T helper (Th) cells and expression of costimulatory signaling molecules affected by adiponectin. The mRNA and protein expression levels of adiponectin and its receptors in oxidized low density lipoprotein cholesterol-treated endothelial cells were assayed by real time PCR and immunofluorescence. The endothelial cells were then treated with adiponectin with or without adipoR1 or adipoR2 siRNA and co-cultured with T lymphocytes. The distribution of Th1, Th2 and Th17 subsets were assayed by flow cytometry. The effects of adiponectin on costimulatory signaling molecules HLA-DR, CD80, CD86 and CD 40 was also assayed by flow cytometry. The results showed that endothelial cells expressed adiponectin and its receptor adipoR1 and adipoR2, but not T-cadherin. Adiponectin suppressed Th1 and Th17 differentiation through adipoR1 receptor, contributed to the inhibition of CD80 and CD40, and inhibited differentiation of Th1 and Th17 by inhibiting antigen presenting action.

Ligation of CD40 receptor in human B lymphocytes triggers the 5-lipoxygenase pathway to produce reactive oxygen species and activate p38 MAPK

Previously, we reported that CD40-induced production of reactive oxygen species (ROS) by NADPH oxidase requires the TNF receptor-associated factor (TRAF) 3, as well as the activities of phosphatidylinositol 3-kinase (PI3K) and Rac1. Here we investigated the possible mechanisms of the production of ROS after CD40 ligation in B cells. We describe an alternative ROS production pathway that is triggered by CD40 ligation, involves 5-lipoxygenase (5-LO), and results in activation of p38 MAPK. Our studies in Raji human B lymphomas revealed that CD40-induced ROS production by 5-LO also requires the activities of PI3K and Rac1. In contrast to the NADPH oxidase pathway, however, TRAF molecules are not required for the CD40-induced ROS production by 5-LO. The association of CD40 with 5-LO is dependent on CD40 ligation in Raji B cells, and co-immunoprecipitation experiments using epitope-tagged proteins transiently expressed in human embryonic kidney 293T cells revealed the role of the regulatory subunit of PI3K, p85, in this association. Collectively, these data suggest a separate pathway for the CD40-induced ROS production in B cells and demonstrate that this pathway requires 5-LO via direct association of p85 with both CD40 and 5-LO.

Defects in blood dendritic cell subsets in HIV-1 subtype C infected Indians.

Background & objective: DCs trigger both innate and adaptive immune responses to control HIV infection and represent a viral reservoir acting as target and HIV carriers for infection of permissive CD4+ T-cells. DCs thus form a very attractive study subject to further our existing knowledge of HIV induced immunopathogenesis due to its diverse and crucial role in HIV infection establishment, viral dissemination, immune evasion, viral persistence, etc. We aimed to characterize the effect of HIV infection on myeloid and plasmacytoid dendritic cell subsets in a group of HIV-1 subtype C infected treated or untreated Indian individuals. Methods: Blood DC subset numbers and immunophenotype were studied for 79 HIV infected subjects at various stages of disease and compared with 13 HIV-uninfected controls. Comparisons were also made between groups of subjects based on their CD4+ T cell counts and also experience of antiretrovirals. Results: Significant decreases were observed in blood DC counts and the two DC subsets in HIV infected individuals. Subjects with lowest CD4+ T cell counts also had a drastically reduced DC subset pool which correlated positively with plasma viraemia and negatively with CD4+ T cell counts. DC subsets from HIV infected subjects showed higher expression of co-stimulatory molecules CD40 and CD86, and HIV-1 co-receptors CXCR4 and CCR5 which correlated positively with HIV-1 plasma viraemia. The alterations in blood DCs were partly resolved in ART receiving study subjects. Interpretation & conclusions: Correlation between DC subset activation state and viraemia supports the role of DC activation on viral replication and CD4+ T cell depletion.

Impaired responses of leukemic dendritic cells derived from a human myeloid cell line to LPS stimulation

Several myeloid leukemia-derived cells have been reported to possess the ability to differentiate into dendritic cells (DC). MUTZ-3, a myeloid leukemia cell line, responds to GM-CSF, IL-4 and TNF-alpha, and acquires a phenotype similar to immature monocyte-derived DC (MoDC). In the present study, MUTZ-3-derived DC (MuDC) showed high level expression of HLA class II molecules, CD80 and CD86, and were able to function as potent antigen presenting cells as previously reported. Interestingly, MuDC maturation was induced by CD40-mediated stimulation, but not by LPS stimulation. We analyzed CCR1, CCR7 and Toll-like receptor (TLR) expressions in MuDC, and measured IL-10 and IL-12 production after maturation stimuli. Although MuDC expressed the mRNA for TLR4, a major component of the LPS receptor system, they did not show an enhanced level of CCR7 or cytokine production after LPS stimulation. In contrast, they responded to CD40 stimulation, which resulted in increased levels of CD83, CD86 and CCR7. Moreover, while LPSstimulated MoDC could potently stimulate NK cells in a DC-NK cell co-culture, LPS-stimulated MuDC failed to stimulate primary NK cells. Taken together, our findings suggest that, although MuDC express TLR4, unlike TNF-alpha and IL-1beta, LPS does not stimulate MuDC to acquire mature phenotypes, and they may have impaired activity to initiate innate immune response.

Distinct immunologic properties of Penicillium marneffei yeasts obtained from different in vitro growth conditions.

A dimorphic fungus Penicillium marneffei is a causative agent of penicilliosis, a life-threatening disseminated disease in immunocompromised hosts predominantly found in southeast Asia and southern China. P. marneffei is the only known Penicillium that possesses a dimorphic characteristic. Since it is difficult to produce large amount of P. marneffei yeasts in vivo for experimentation purpose, yeast cells were produced in different in vitro conditions as alternatives. We interested in investigating the immunologic properties of yeast cells from different culture preparations. It was found that yeast cells obtained from brain heart infusion broth and Sabouraud dextrose broth did not resemble those resided in clinical specimens. A solution of 1% peptone, on the other hand, could induce a direct conidial transition into fission yeasts. Ability of yeast cells in each preparation to activate macrophages was determined by analyzing surface expression of CD40 and CD86 co-stimulatory molecules after two days of co-cultivation. Every P. marneffei yeast cell preparation demonstrated such ability. However, the ones from Sabouraud dextrose broth seemed to induce less phagocytosis. Additionally, although distinct antigenic profiles and lack of conformity in antigenic expression were observed among yeast cells from different culture conditions, most major immunogenic bands were present when Western analysis was performed using polyclonal antisera from penicilliosis patients. The results of the study raise attention on immunological and biochemical characteristics of P. marneffei yeasts if such preparations are to be used in future laboratory investigations.

Expression of CD40 and Fas Ligand in Bowen's Disease, Squamous Cell Carcinoma and Basal Cell Carcinoma

Impaired regulation of apoptosis is known to be associated with the development of various cancers, and Fas/Fas-ligand (FasL) is known to play an important role in apoptosis. CD40 is a cell surface receptor, which when ligated modulates apoptosis in some cell types. The expressions of CD40 and FasL were examined in 10 normal skins, 7 Bowen's disease skins, 10 squamous cell carcinomas (SCCs) and 12 basal cell carcinomas (BCCs) immunohistochemically. In the normal epidermis, CD40 was more highly expressed in the keratinocytes of the squamous cell and granular layers than in those of the basal layer, and FasL expression was observed in the cell membrane of keratinocytes at the basal and squamous cell layers. CD40 expression was significantly higher in SCCs than in normal or Bowen's disease skin, while FasL expression was significantly higher in Bowen's disease than in SCCs. BCCs expressed the lowest levels of CD40 and FasL. These results suggest that altered CD40 and FasL expression may be related with the progression of SCC, and the marked reduced expression of CD40 and FasL may explain the biologic behavior of BCCs.

Preliminary results on the effects of CD40/CD40L interactions and SAC-induction on IFN-gamma expression in human schistosomiasis

In this communication the authors analyzed the pattern of expression of IFN-gamma as a surrogate type 1 response in different clinical forms of schistosomiasis in response to stimulation involving T-cell dependent and T-cell independent pathways, to investigate which pathways were functional in human schistosomiasis, and to further characterize the nature of Th1 response impairment in this parasitic disease

Expression of CD40 and Apoptosis Related Molecules in Autoimmune Thyroid Diseases

Apoptosis is responsible for the loss of thyrocytes in autoimmune thyroiditis. Recent investigations into the pathogenesis of apoptosis have revealed that the important roles of suicide molecules expression on both thyrocytes and cytotoxic T-lymphocytes. To study the mechanism of thyrocyte loss in various forms of thyroiditis, we evaluated in situ expression patterns of CD40, Fas, and Fas-L on thyrocytes and infiltrating inflammatory cells by immunohistochemical staining of thyroid samples obtained from 49 patients (Graves' disease, n=10 : Hashimoto's thyroiditis, n=14; nonspecific lymphocytic thyroiditis, n=11; subacute granulomatous thyroiditis, n=11; normal, n=3). The role of cytotoxic T-lymphocytes was also evaluated by analyzing the expression of granzyme B along with their phenotypic characteristics. CD40 was not expressed on thyrocytes of normal controls while they showed a diffuse expression of Fas and a scattered focal expression of Fas-L. The plump thyrocytes proximal to the inflammatory infiltrates showed more intense expressions of these three molecules in various forms of thyroiditis and a close correlation was found between CD40 and Fas-L expression on thyrocytes. Unlike Fas, which was expressed on infiltrating lymphocytes in all groups, Fas-L was not expressed on infiltrating lymphocytes, except those in subacute granulomatous thyroiditis. Granzyme B expressing activated cytotoxic T-lymphocytes occupied a negligible proportion of CD8+ T-lymphocytes in various forms of thyroiditis, and no difference was found in terms of their proportions according to the type of thyroiditis. These results show the acquisition of CD40, Fas and Fas-L molecules on thyrocytes proximal to inflammatory cell aggregates and the negligible expression of granzyme B and Fas-L on the infiltrating lymphocytes, and suggest that Fas and Fas-L mediated apoptosis of thyrocytes (fratricide) may be more important than T cell-mediated cytotoxicity in various forms of thyroiditis.