No evidence of pathogenic involvement of cathelicidins in patient cohorts and mouse models of lupus and arthritis.

Apart from their role in the immune defence against pathogens evidence of a role of antimicrobial peptides (AMPs) in autoimmune diseases has accumulated in the past years. The aim of this project was to examine the functional impact of the human cathelicidin LL-37 and the mouse cathelicidin-related AMP (CRAMP) on the pathogenesis of lupus and arthritis. Serum LL-37 and anti-LL-37 levels were measured by ELISA in healthy donors and patients with Systemic Lupus Erythematosus (SLE) and Rheumatoid arthritis (RA). Pristane-induced lupus was induced in female wild type (WT) and cathelicidin-deficient (CRAMP-/-) mice. Serum levels of anti-Sm/RNP, anti-dsDNA, and anti-histone were determined via ELISA, cytokines in sera and peritoneal lavages were measured via Multiplex. Expression of Interferon I stimulated genes (ISG) was determined by real-time PCR. Collagen-induced arthritis (CIA) was induced in male WT and CRAMP-/- mice and arthritis severity was visually scored and analysed histomorphometrically by OsteoMeasure software. Serum levels of anti-LL-37 were higher in SLE-patients compared to healthy donors or patients with RA. However, no correlation to markers of disease activity or organ involvement was observed. No significant differences of autoantibody or cytokine/chemokine levels, or of expression of ISGs were observed between WT and CRAMP-/- mice after pristane-injection. Furthermore, lung and kidney pathology did not differ in the absence of CRAMP. Incidence and severity of CIA and histological parameters (inflammation, cartilage degradation, and bone erosion) were not different in WT and CRAMP-/- mice. Although cathelicidins are upregulated in mouse models of lupus and arthritis, cathelicidin-deficiency did not persistently affect the diseases. Also in patients with SLE, autoantibodies against cathelicidins did not correlate with disease manifestation. Reactivity against cathelicidins in lupus and arthritis could thus be an epiphenomenon caused by extensive overexpression in blood and affected tissues. In addition, other cationic AMPs could functionally compensate for the deficiency of cathelicidins.

Are T cells from healthy heart really only passengers? Characterization of cardiac tissue T cells.

Numerous studies have dealt with occurrence of dendritic cells in various nonlymphoid organs such as kidney, liver or heart, whereas lymphocyte patterns in these organs have not been analyzed in detail. In the present study, leukocytes were quantified as cells/mm2 in the perivascular, interstitial and parenchymal tissue sections of normal heart. We measured an overall mean leukocyte count in normal heart tissue of 17.0 +/- 2.7 CD45+ leukocytes/mm2, 9.1 +/- 1.8 thereof being CD4+ T-helper cells (Th). By comparison, CD8+ T-cytotoxic/suppressor cells (Ts) and CD14+ macrophages each accounted for only approximately 2.5 cells/mm2, and CD20+ B cells for only 1.3 cells/mm2. These T cells were further characterized as either CD45RA+ naive T cells or as CD45RO+ memory T cells. Segmentation of the tissue as defined in Section 2 yielded an ascending number of CD45RO+ memory T cells from perivascular (0.4 +/- 0.2 cells/mm2) through parenchymal (12.8 +/- 3.0 cells/mm2) to interstitial (21.0 +/- 5.3/mm2). By contrast, the number of CD45RA+ and Leu-8+ cells decreased from perivascular to parenchymal. Peripheral T cells showed a reverse pattern of CD45RA/CD45RO antigen expression. Only approximately 3% of T cells expressed activation markers IL-2R and IL7R. Our data demonstrate that the majority of T cells in normal heart tissue are resting memory tissue T cells and are not contaminating T cells from the peripheral blood. The increase in CD45RO+ cells from perivascular to parenchymal with a corresponding decrease in CD45RO+ and Leu-8+ heart-tissue T cells argues in favor of T-cell traffic in normal heart tissue.

Phenotypic patterns of mononuclear cells in dilated cardiomyopathy.

BACKGROUND: Immunological factors in the pathogenesis of idiopathic dilated cardiomyopathy (IDC) were suggested previously on the basis of the demonstration of mononuclear cell infiltrates and autoantibodies against the myocardium. The present study investigated whether tissue leukocyte subpopulations isolated from hearts with IDC (n = 6) differ in phenotype from those of tissues without IDC (n = 7). METHODS AND RESULTS: Leukocytes were quantified as reactive cells per square millimeter in perivascular, interstitial, and parenchymal tissue sections. Freshly isolated heart-tissue T cells and peripheral-blood T cells from the same patients were analyzed by triple staining and flow cytometry to identify T-cell subpopulations as well as their states of differentiation (expression of CD45RA and Leu-8 versus CD45RO) and activation (IL-2R, IL-7R, very late antigen-1, HLA-DR). All types of infiltrating cells (T cells, B cells, macrophages, granulocytes) are increased in hearts with IDC compared with normal hearts, but only CD8+ T cells and macrophages are increased relative to the other leukocyte subpopulations. CD45RO+/CD45RA-/Leu-8- cells constitute the majority of heart-tissue T cells in both normal hearts and hearts with IDC. Strikingly, hearts with IDC are infiltrated by eightfold greater numbers of perivascularly located IL-2R(+)- (26% of all T cells) and CD45RO(+)-activated memory T cells; moreover, in contrast to normal heart, approximately 40% of both CD4+ and CD8+ heart-tissue T cells express activation markers. CONCLUSIONS: Both normal hearts and hearts with IDC are populated by leukocytes. The quantitative increase in IDC, associated with a dramatically altered activation status of heart-tissue T cells, suggests a direct role of infiltrating leukocytes in the pathogenesis of IDC.