The β2-adrenoceptor agonist clenbuterol reduces the neuroinflammatory response,neutrophil infiltration and apoptosis following intra-striatal IL-1β administration to rats

Objectives: Clenbuterol is a brain penetrant β₂-adrenoceptor agonist with anti-inflammatory and putative neuroprotective properties. In the present investigation, the effect of clenbuterol was assessed in a rat model of acute brain injury induced by intra-striatal administration of the pro-inflammatory cytokine IL-1β.

Methods: Clenbuterol (0.5?mg/kg; i.p.) was administered one hour prior to stereotactically delivered IL-1β (100?ng) into the striatum. Four hours postinjection, rats were anesthetized, blood samples were collected for circulating cytokine and chemokine analysis, and the ipsilateral striatum and liver tissue were harvested for mRNA expression analysis of target genes.

Results: Intrastriatal IL-1β provoked an inflammatory response with increased expression of IL-1β and the pro-inflammatory cytokine TNF-α. TNF-α expression was also increased in the liver and circulating concentrations of the chemokine cytokine-induced neutrophil chemoattractant 1 (CINC-1) were raised in response to intrastriatal IL-1β administration. The striatal response was accompanied by NFκB activation and 24?hours postinjection, increased immunoreactivity of the neutrophil marker MBS-2, indicative of cell infiltration and increased TUNEL staining, a cell marker of apoptosis. Treatment with clenbuterol attenuated all IL-1β-induced changes in the striatum including MBS-2 immunoreactivity and TUNEL?+?staining. Clenbuterol also attenuated IL-1β-induced expression of TNF-α in the liver and the increase in circulating CINC-1 concentrations.

Conclusions: The results provide evidence that clenbuterol elicits anti-inflammatory effects, suppresses the peripheral acute phase response and reduces the infiltration of neutrophils and apoptotic response to acute IL-1β–induced brain injury. Suppression of both the central and peripheral response following clenbuterol administration may contribute to its protective properties following brain injury.     

Antigen recognition by MHC-incompatible cells of a human mismatched chimera

Tetanus toxin (TT)-specific T cell clones of donor origin were obtained from a patient with severe combined immunodeficiency (SCID) successfully reconstituted by transplantation of allogeneic fetal liver and thymus cells from two different donors performed 10 yr ago. A series of these clones recognized TT in the context of "allo" class II HLA determinants expressed by recipient APC. The restriction element of two T cell clones with the HLA phenotype of the first donor (HLA-DR1,8) and one T cell clone with the HLA phenotype of the second transplant (HLA-DR3,9) was HLA-DR4 of the recipient, whereas other T cell clones derived from the second transplant recognized TT in the context of HLA-DR5 of the recipient's APC. These latter T cell clones were not able to proliferate in response to TT when autologous APC were used. These data demonstrate that recipient and donor cells having different HLA phenotypes could cooperate across the allogeneic barrier and that MHC restriction of antigen (Ag) recognition is independent from the MHC genotype of the T cells but is influenced by the environment in which the T cells mature. We also isolated T cell clones that were able to recognize processed TT presented by all allogeneic EBV cell lines tested, indicating that the Ag specificity of these clones was not restricted by a particular class II MHC molecule. The Ag-specific proliferative response of one of these clones could be blocked by anti-class II MHC mAbs. These results demonstrate that in addition to Ag recognition in the context of specific class II MHC Ags, other types of Ag-specific responses may occur in this human chimera. It is not clear whether this "allo" plus Ag recognition is the result of education of transplanted fetal cells in the host thymus. Taking into consideration our previous findings indicating that alloreactive T cell clones specific for the recipient cells could be isolated in vitro from the PBL of the same patient, our data suggest that the mechanism for deletion of self-reactive clones and the generation of MHC-restricted responses are different.     

Autoreactive T cell clones specific for class I and class II HLA antigens isolated from a human chimera

T cell clones of donor origin that specifically react with recipient cells were obtained from a SCID patient successfully reconstituted by allogeneic fetal liver and thymus transplantation performed 10 yr ago. The majority of these clones displayed both cytotoxic and proliferative responses towards PBL and an EBV-transformed B cell line derived from the patient. In addition, these T cell clones had proliferative and cytotoxic responses towards the parental PBL, EBV cell lines, and PHA blasts. Blocking studies with anti-class I and anti-class II HLA mAbs indicated that the activity of the CD4+ T cell clones was specifically directed against class II HLA antigens of the recipient. On the other hand, the cytotoxic and proliferative responses of the CD8+ T cell clones were specific for class I HLA antigens which are ubiquitously expressed on the recipient cells. Thus, the establishment of transplantation tolerance observed in this stable human chimera is not due to the elimination of host-reactive T cells from the repertoire and suggests the presence of a peripheral autoregulatory suppressor mechanism.     

The T-cell receptor gamma chain-CD3 complex: implication in the cytotoxic activity of a CD3+ CD4- CD8- human natural killer clone

A subset of human T cells has recently been described. These cells express the CD3 complex but they do not carry the classical T-cell receptor (TCR)-alpha/-beta heterodimer on their surface (WT31- CD3+). Instead, they express a TCR-gamma chain associated with another type of polypeptide termed TCR-delta. We report here that a T-cell clone with natural killer (NK)-like activity, WM-14, had a disulfide bridged TCR-gamma homodimer associated with CD3 on its surface. The TCR-gamma chains of WM-14 cells were present in three different glycosylation forms of 43, 40, and 38 kDa, but they appeared to contain the same polypeptide backbone. Since cytotoxicity by WM-14 could be inhibited by anti-CD3 antibodies, we concluded that the TCR-gamma-CD3 complex was involved in the NK-like unrestricted killer activity. Although normal CD3-gamma, CD3-delta, and CD3-epsilon chains were present in this clone, the association with the TCR-gamma homodimer may be the cause of a complete processing of the N-linked oligosaccharides attached to the CD3-delta chain.     

Geographical-level contributions of risk factors for HIV infections using generalized additive models: results from a cohort of South African women

South Africa has the highest burden of human immunodeficiency virus (HIV) infections in the world with significant geographical variations. We identified the predictors of HIV infections and their sub-geographical-level contributions to the epidemic using a decade long data (2002–2012) from 6484 South African women. Generalized additive models were used to uncover the most significant features of these estimates across the region. In the overall analysis, younger age, not married or cohabiting with a partner, partner has another partner(s) and null/prim parity, using injectable contraceptives and presence of other sexually transmitted infections (STIs) were identified as independent predictors of HIV seroconversions. Overall, the top three highest contributors to infections were women’s marital status (PAR%?=?73%, 95% CI: 68%, 77%), parity (PAR%?=?47%, 95% CI: 42%, 53%) and partnership factors (PAR%?=?37%, 95% CI: 30%, 44%). However, their contributions varied remarkably at sub-geographical level. This was mainly due to the substantial localized variations in their prevalence and hazard ratios across the region. Our results will guide policy makers to develop tailored prevention strategies in order to allocate scarce resources by targeting the most significant contributors of HIV infection at sub-geographical level.     

Reactivity of cloned, expressed human Fc gamma RIII isoforms with monoclonal antibodies which distinguish cell-type-specific and allelic forms of Fc gamma RIII.

We have isolated and expressed a cDNA encoding human NK cell Fc gamma RIII. The NK cell cDNA differs from the neutrophil Fc gamma RIII cDNA by a number of point mutations and encodes an additional 21 amino acids at its C-terminus. When transiently expressed neutrophil and NK cell Fc gamma RIII were digested with N-glycanase, deglycosylated neutrophil Fc gamma RIII had a more rapid electrophoretic mobility than NK cell Fc gamma RIII, as is observed for the human Fc gamma RIII isoforms on normal cells. The neutrophil and NK cell Fc gamma RIII isoforms apparently result from cell-type specific expression of different forms of Fc gamma RIII mRNA. A TaqI RFLP was also found for human Fc gamma RIII. Monoclonal antibodies which have been used to distinguish the neutrophil and NK cell Fc gamma RIII isoforms and the NA1 and NA2 alleles of human neutrophil Fc gamma RIII were employed to study the expression of two Fc gamma RIII cDNA clones derived from neutrophils and NK cells. Fc gamma RIII encoded by the neutrophil-derived cDNA reacts with the monoclonal antibody CLBgran11, while the NK-cell Fc gamma RIII cDNA expresses the Fc receptor which carries an antigenic determinant recognized by the antibody GRM1. Characterization of hybrid Fc gamma RIII constructed by interchange of restriction fragments between the neutrophil and NK cell cDNAs allowed localization of antigenic determinants recognized by the monoclonal antibodies.     

A single sub-erythematous exposure of solar-simulated radiation on the elicitation phase of contact hypersensitivity induces IL-10-producing T-regulatory cells in human skin

Solar ultraviolet (UV) radiation has hazardous effects on human health that are, in part, associated with its immunosuppressive effects via the induction of interleukin (IL)-10 production. Although IL-10 is produced by both T helper type 2 (Th2) cells and T-regulatory type 1 (Tr1) cells, the relative contribution of either subset in UV radiation-induced immunosuppression has not been established. Here, we show that T cells isolated from non-treated allergic contact dermatitis (ACD) reactions, 48 h following nickel challenge and propagated for 7-10 days in the presence of IL-2, were mainly CD4(+) and produced IL-10, but little interferon-gamma. A single sub-erythematous solar-simulated radiation (SSR) prior to antigen challenge exposure resulted in a clinical attenuation of the intensity of ACD reactions which was associated with a significant increase in both the magnitude of IL-10 production by skin-infiltrating T cells and the frequency of IL-10-producing Tr1 cells. Skin-infiltrating T cells in SSR-exposed, as well as non-exposed, ACD reactions showed a perturbed T-cell receptor (TCR)-Vbeta repertoire, without overexpression of a particular TCR-Vbeta gene product, indicating the presence of high frequencies of nickel non-specific T cells in ACD reactions. These results show that a single sub-erythematous SSR induces immunosuppression via the cutaneous infiltration of IL-10-producing Tr1, and to a lesser extent, Th2 cells.