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Crohn’s disease (CD) is a chronic inflammatory disease of the gastrointestinal tract. Its pathogenesis is not completely understood, though the prevailing model is that the intestinal flora drives a strong intestinal T helper 1 (Th1)/Th17 type immune response and inflammation in the genetically susceptible host. This leads to overly aggressive T-cell responses to normal bacteria causing tissue damage. Intestinal homeostasis and maintenance of tolerance to harmless antigens in the intestine has been shown to be maintained by CD4+ CD25+ T regulatory cells (Treg) in animal models of inflammatory bowel diseases. Here we investigated whether Infliximab, a chimeric monoclonal antibody directed against tumour necrosis factor (TNF)-α shown to be highly effective in the treatment of CD, has any effect on mucosal CD4+ CD25+ (FOXP3+) Tregs. Colonic mucosal biopsies from children with active Crohn’s disease treated in vivo with Infliximab and controls were analysed to determine FOXP3 expression by immunofluorescence and reverse transcription–polymerase chain reaction. We observed that FOXP3+ T cells were significantly reduced in mucosa of CD patients with active disease compared with controls and restored to normal following Infliximab treatment. The frequency of FOXP3+ cells and mRNA expression was significantly increased in CD mucosa from patients treated in vivo with Infliximab compared with CD patients treated with conventional therapies. In conclusion, we show that Infliximab treatment does not solely neutralize soluble TNF-α, but also affects activation and possibly expansion of mucosal regulatory T cells. We suggest that anti TNF-α immunotherapy can also restore mucosal homeostasis in Crohn’s disease. [ABSTRACT FROM AUTHOR]

Background Recent studies in animal models indicate a role for natural killer (NK) cells in the protection against type 1 diabetes. In humans, a reduction of NK cell numbers has been reported in identical twins discordant for type 1 diabetes, irrespective of whether they have the disease. Here we have tested whether the activation and expansion of human NK cells with lipopolysaccharide (LPS) reveals differences between these twins. Methods Proportions of CD56+ NK cells and T-cells and Va24Vb11+ NK-T cells from diabetic and non-diabetic twins was assessed before and after activation using flow cytometry. NK receptor usage was monitored by PCR and flow cytometry. Results The profile of the expressed Killer Cell immunoglobulin-like receptor (KIR) repertoire (using mRNA) in freshly isolated NK cells was identical in pairs of identical twins, despite marked variation among individual twins as well as controls. Basal numbers of CD56+ and CD94+ (CD3− and CD3+) cells and Vα24+Vβ11+ NK-T cells were similarly strongly correlated between identical twins ( p < 0.006 for all correlations). Following LPS stimulation, the pattern of KIR mRNA expression remained unaltered in twins and the proportion of NK cells and Vα24+Vβ11+ NK-T cells remained correlated between pairs of twins. However, there was a significant reduction in the proportion of CD56+ cells and CD94+ cells (whether defined as CD3− or CD3+) responding to LPS in the diabetic compared to the non-diabetic twin ( p = 0.031 and 0.025, respectively). Conclusion: This reduction in NK cell expansion in response to LPS in patients with type 1 diabetes is consistent with a non-genetically determined alteration in the innate immune response either predisposing to or resulting from the disease. Copyright © 2006 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Summary We have shown previously that interleukin-10 (IL-10) blocks the development and T-cell stimulatory capacity of human monocyte-derived dendritic cells, without apparently down-regulating the surface expression of co-stimulatory molecules or human leucocyte antigen (HLA) molecules. In the majority of donors (60%), the cell surface levels of HLA-DR actually increased upon IL-10 treatment. Here we have shown that IL-10 does not regulate HLA-DR transcription as assessed by polymerase chain reation. Epifluorescence microscopy analysis showed that IL-10 primarily increased the intracellular pool of HLA-DR. In fact, IL-10 directly increased HLA-DR protein synthesis. However, IL-10 did not significantly alter the synthesis of invariant chain (Ii), which plays a crucial role in the assembly, transport and loading of newly formed HLA class II molecules, nor the amount of Ii reaching the cell-surface. In contrast, IL-10 increased the amount of HLA-DR-bound Iip33 shortly after the HLA-DR complex assembly. We postulate that, upon IL-10 treatment, immature Ii-associated HLA II molecules can still transit to the cell surface as they do in immature dendritic cells and recycle to the intracellular space, where they accumulate. A higher proportion of Ii-associated HLA-DR, coupled to increased membrane recycling, may contribute to the lower T-cell stimulatory capacity of IL-10-treated dendritic cells. [ABSTRACT FROM AUTHOR]

Summary Dendritic cells (DCs) have an essential role in the initiation of immune responses as they deliver antigen/epitope and the appropriate signals to activate naïve T cells and thus start an immune response. In order to fulfil their function, DCs have to patrol different part of the body, thus migrating through the extracellular matrix to sample the local ‘antigenic’ environment. In the present study, we have investigated which enzymes might be involved in this process using the Matrigel trans-well migration assay, an in vitro model of extracellular matrix migration. In this assay we analysed the migratory ability of interleukin-4 (IL-4)/granulocyte macrophage–colony-stimulating factor (GM-CSF)-derived immature DCs as well as mature DCs, induced by tumour necrosis factor-α (TNF-α) and modified vaccinia virus Ankara (MVA). The ‘mature’ DCs showed an increased migration through Matrigel, which was significantly inhibited by inhibitors of matrix metalloproteinases (MMP). We also observed that the dominant MMP involved in this process was MMP-9, and a concomitant decrease of the endogenous tissue inhibitors of metalloproteinases (TIMP)-1 and TIMP-2 was also observed. Collectively these data suggest that the balance between MMP/TIMP determines the net migratory capacity of human DCs. Surprisingly, TIMP-3 was significantly increased in mature DC. Our data thus indicate that MMP and TIMP play a role in the migratory ability of human DCs. Our results also suggest that TIMP-3 expression might represent a new marker of maturation of human DCs. [ABSTRACT FROM AUTHOR]

Background: Recent studies in animal models indicate a role for natural killer (NK) cells in the protection against type 1 diabetes. In humans, a reduction of NK cell numbers has been reported in identical twins discordant for type 1 diabetes, irrespective of whether they have the disease. Here we have tested whether the activation and expansion of human NK cells with lipopolysaccharide (LPS) reveals differences between these twins., Methods: Proportions of CD56(+) NK cells and T-cells and Va24Vb11(+) NK-T cells from diabetic and non-diabetic twins was assessed before and after activation using flow cytometry. NK receptor usage was monitored by PCR and flow cytometry., Results: The profile of the expressed Killer Cell immunoglobulin-like receptor (KIR) repertoire (using mRNA) in freshly isolated NK cells was identical in pairs of identical twins, despite marked variation among individual twins as well as controls. Basal numbers of CD56(+) and CD94(+) (CD3(-) and CD3(+)) cells and Valpha24(+)Vbeta11(+) NK-T cells were similarly strongly correlated between identical twins (p < 0.006 for all correlations). Following LPS stimulation, the pattern of KIR mRNA expression remained unaltered in twins and the proportion of NK cells and Valpha24(+)Vbeta11(+) NK-T cells remained correlated between pairs of twins. However, there was a significant reduction in the proportion of CD56(+) cells and CD94(+) cells (whether defined as CD3(-) or CD3(+)) responding to LPS in the diabetic compared to the non-diabetic twin (p = 0.031 and 0.025, respectively)., Conclusion: This reduction in NK cell expansion in response to LPS in patients with type 1 diabetes is consistent with a non-genetically determined alteration in the innate immune response either predisposing to or resulting from the disease.