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Psoriasis is a chronic inflammatory disease appearing as scaly erythematous cutaneous lesions, which are characterized by parakeratosis and acanthosis as well as the infiltration of immune cells, such as T helper-1 and T helper-17 cells. Here, we demonstrated that Kd PT, a tripeptide structurally related to the C-terminal amino acids of alpha-melanocyte-stimulating hormone, which was previously shown to exhibit anti-inflammatory effects in intestinal inflammation, ameliorated ongoing disease in the mouse model of imiquimod-induced psoriasis-like skin inflammation and in the small xenotransplant mouse model of psoriasis. We could show that systemic Kd PT treatment significantly reduced hyperkeratosis and acanthosis in murine as well as human skin. Moreover, Kd PT upregulated Foxp3 in CD4+ T cells from mice and from peripheral blood of individuals with psoriasis and decreased the expression of type 1 inflammatory cytokines, indicating that the beneficial effect of Kd PT was, at least in part, mediated by the induction of functional regulatory T cells that suppressed the activation of pathogenic CD4+ IFN-γ+ and CD4+ IL-17+ T cells. Thus, these data might suggest Kd PT as a potential novel therapeutic alternative for the treatment of psoriasis. [ABSTRACT FROM AUTHOR]

The article discusses a study on the effect of the Nle4-D-Phe7-melanocyte-stimulating hormone (NDP-MSH) on neuroinflammatory disease, such as multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE). The study used mouse models to show the effect of the drug on the progression of EAE. It also examined the role of the drug in the prevention of immune cell infiltration into the central nervous system (CNS).

Background: Different non-invasive real-time imaging techniques have been developed over the last decades to study bacterial pathogenic mechanisms in mouse models by following infections over a time course. In vivo investigations of bacterial infections previously relied mostly on bioluminescence imaging (BLI), which is able to localize metabolically active bacteria, but provides no data on the status of the involved organs in the infected host organism. In this study we established an in vivo imaging platform by magnetic resonance imaging (MRI) for tracking bacteria in mouse models of infection to study infection biology of clinically relevant bacteria. Results: We have developed a method to label Gram-positive and Gram-negative bacteria with iron oxide nano particles and detected and pursued these with MRI. The key step for successful labeling was to manipulate the bacterial surface charge by producing electro-competent cells enabling charge interactions between the iron particles and the cell wall. Different particle sizes and coatings were tested for their ability to attach to the cell wall and possible labeling mechanisms were elaborated by comparing Gram-positive and -negative bacterial characteristics. With 5-nm citrate-coated particles an iron load of 0.015 ± 0.002 pg Fe/bacterial cell was achieved for Staphylococcus aureus. In both a subcutaneous and a systemic infection model induced by iron-labeled S. aureus bacteria, high resolution MR images allowed for bacterial tracking and provided information on the morphology of organs and the inflammatory response. Conclusion: Labeled with iron oxide particles, in vivo detection of small S. aureus colonies in infection models is feasible by MRI and provides a versatile tool to follow bacterial infections in vivo. The established cell labeling strategy can easily be transferred to other bacterial species and thus provides a conceptual advance in the field of molecular MRI. [ABSTRACT FROM AUTHOR]

Mrp8 and Mrp14 are endogenous alarmins amplifying inflammation via Toll-like receptor-4 (TLR-4) activation. Due to their pro-inflammatory properties, alarmins are supposed to enhance adaptive immunity via activation of dendritic cells (DCs). In contrast, analysing a model of allergic contact dermatitis (ACD) we observed a more severe disease outcome in Mrp8/14-deficient compared to wild-type mice. This unexpected phenotype was associated with an enhanced T-cell response due to an accelerated maturation of DCs in Mrp8/14-deficient mice. Accordingly, Mrp8, the active component of the heterocomplex, inhibits early DC maturation and antigen presentation in a TLR-4-dependent manner. Transfer of DCs purified from the local lymph nodes of sensitized Mrp8/14-deficient to wild-type mice determined the outcome of ACD. Our results link a pro-inflammatory role of the endogenous TLR-4 ligand Mrp8/14 to a regulatory function in adaptive immunity, which shows some similarities with the 'hygiene hypothesis' regarding continuous TLR-4 stimulation and decreased risk of allergy. [ABSTRACT FROM AUTHOR]

Specific inhibition of the entry of encephalitogenic T lymphocytes into the central nervous system in multiple sclerosis would provide a means of inhibiting disease without compromising innate immune responses. We show here that targeting lymphocyte interactions with endothelial basement membrane laminins provides such a possibility. In mouse experimental autoimmune encephalomyelitis, T lymphocyte extravasation correlates with sites expressing laminin α4 and small amounts of laminin α5. In mice lacking laminin α4, laminin α5 is ubiquitously expressed along the vascular tree, resulting in marked and selective reduction of T lymphocyte infiltration into the brain and reduced disease susceptibility and severity. Vessel phenotype and immune response were not affected in these mice. Rather, laminin α5 directly inhibited integrin α6β1–mediated migration of T lymphocytes through laminin α4. The data indicate that T lymphocytes use mechanisms distinct from other immune cells to penetrate the endothelial basement membrane barrier, permitting specific targeting of this immune cell population. [ABSTRACT FROM AUTHOR]

Autoimmunity results from loss of mechanisms controlling self-reactivity. Autoimmune disorders play an increasingly important role and CD40–CD40 ligand (CD40L) interaction on immunocompentent cells is able to break established immunotolerance. To study the effects of the calcineurin-inhibitor FK506 on CD40L-induced systemic autoimmunity, CD40L transgenic (tg) mice, which spontaneously develop a mixed connective tissue-like disease, were treated with FK506 after onset of overt autoimmunity. Interestingly, FK506-treated CD40L tg mice showed significantly reduced autoimmune dermatitis scores and markedly decreased numbers of lesional infiltrating leukocytes. This finding was associated with diminished lymphadenopathy induced by FK506 treatment. Furthermore, FK506 suppressed the development of cytotoxic/autoreactive CD8+ T cells as evidenced by the reduced expression of T cell activation markers in treated CD40L tg mice. Importantly, FK506 induced a significant reduction in autoantibody titers in the serum of CD40L tg animals. As CD40L tg mice develop nephritis leading to loss of renal function proteinuria was determined after FK506 injections. Notably, FK506 treatment re-established renal function as indicated by significantly reduced uric protein concentrations of treated CD40L tg mice. Together, these findings show the beneficial therapeutic effects of FK506 for the treatment of CD40L-induced autoimmunity. Additionally, these results demonstrate that FK506 is able to suppress ongoing severe autoimmune responses.Journal of Investigative Dermatology (2006) 126, 1307–1315. doi:10.1038/sj.jid.5700185; published online 9 February 2006 [ABSTRACT FROM AUTHOR]

The neuropeptide α-melanocyte-stimulating hormone (α-MSH) is a well-known mediator of skin pigmentation. More recently, it has been shown that α-MSH also exerts a strong anti-inflammatory and immunosuppressive activity. To elucidate the mechanisms underlying α-MSH-induced immunosuppression, we investigated whether α-MSH affects dendritic cell/T cell communication, as especially this interaction has an important role in the regulation of immune responses. Here, we show that α-MSH, by binding to MC-1R, induced tolerogenic dendritic cells, which were capable of expanding CD4+CD25+Foxp3+ regulatory T cells (Tregs) in vitro, as well as in vivo. Notably, those α-MSH-induced Tregs were functional as they efficiently inhibited cutaneous contact allergy and ongoing psoriasis-like skin inflammation in mice. Furthermore, α-MSH induced tolerogenic dendritic cells capable of generating functional Tregs in human blood. Interestingly, human Tregs expanded via α-MSH-stimulated dendritic cells suppressed the proliferation and cytokine secretion of pathogenic T-helper-17 (Th17) cells from individuals with psoriasis. Taken together, these data indicate that α-MSH induced immunosuppressive Tregs in vitro and in vivo, which inhibited disease progression in a mouse model of psoriasis-like skin inflammation and suppressed the activation and proliferation of effector T cells from subjects with psoriasis. [ABSTRACT FROM AUTHOR]