The role of B cells in systemic sclerosis

Systemic sclerosis (SSc) is a connective disease characterized by features of autoimmunity, vasculopathy, inflammation, and fibrosis. The disease typically starts with Raynaud’s phenomenon, followed by skin thickening in the extremities due to inflammation and fibrosis. Fibrosis results from excessive collagen production by fibroblasts, which constitutes the final common pathway of complex cellular interactions including B cells. Several studies have indicated that B cells may play a role in SSc. Lesional skin infiltrates from SSc patients consist of a variety of cells, including eosinophils, neutrophils, lymphocytes, plasma cells, and macrophages. Autoantibodies of several specificities are present in the serum of SSc patients of which antitopoisomerase 1 is the most common, and evidence has been gathered for a potential pathogenic role of some autoantibodies, eg, anti-PDGF antibodies. The blood of SSc patients contains an increased proportion of naïve B cells but a decreased proportion of memory B cells. Furthermore, serum levels of interleukin-6, an important pro-inflammatory cytokine, have been shown to correlate with skin fibrosis. Animal models of SSc have provided more in-depth information on the role of B lymphocytes, eg, through disruption of B cell function. In this review we will discuss the evidence that B cells are involved in the pathogenesis of SSc

CATH-2 and LL-37 increase mannose receptor expression, antigen presentation and the endocytic capacity of chicken mononuclear phagocytes

Cathelicidins display in vitro and in vivo immunomodulatory activities and are part of the innate immune system. Previously, we found that in ovo treatment with chicken cathelicidin CATH-2 partially protects young broilers against respiratory E. coli infection. To determine the cellular aspects of this protection, we investigated immunomodulatory effects of CATH-2 and the human cathelicidin LL-37 on primary chicken peripheral blood mononuclear cells (PBMCs). Treatment of chicken PBMCs with L-CATH-2, D-CATH-2 or LL-37 increased the percentage of mononuclear phagocytes, but decreased that of B cells. L-CATH-2, D-CATH-2 and LL-37 treatment of chicken PBMCs also enhanced the expression levels of mannose receptor MRC1 and antigen presentation markers MHCII, CD40 and CD86 on mononuclear phagocytes, indicating increased antigen presentation capacity. Concomitantly, L-CATH-2, D-CATH-2 and LL-37 neutralized LPS-induced cytokine production, while increasing the endocytic capacity. We conclude that L-CATH-2, D-CATH-2 and LL-37 can modulate the immune response of primary chicken immune cells by increasing mannose receptor expression, antigen presentation, endocytosis and neutralizing LPS-induced cytokine production and as a result augment activation of the adaptive immune system

CATH-2 and LL-37 increase mannose receptor expression, antigen presentation and the endocytic capacity of chicken mononuclear phagocytes

Cathelicidins display in vitro and in vivo immunomodulatory activities and are part of the innate immune system. Previously, we found that in ovo treatment with chicken cathelicidin CATH-2 partially protects young broilers against respiratory E. coli infection. To determine the cellular aspects of this protection, we investigated immunomodulatory effects of CATH-2 and the human cathelicidin LL-37 on primary chicken peripheral blood mononuclear cells (PBMCs). Treatment of chicken PBMCs with L-CATH-2, D-CATH-2 or LL-37 increased the percentage of mononuclear phagocytes, but decreased that of B cells. L-CATH-2, D-CATH-2 and LL-37 treatment of chicken PBMCs also enhanced the expression levels of mannose receptor MRC1 and antigen presentation markers MHCII, CD40 and CD86 on mononuclear phagocytes, indicating increased antigen presentation capacity. Concomitantly, L-CATH-2, D-CATH-2 and LL-37 neutralized LPS-induced cytokine production, while increasing the endocytic capacity. We conclude that L-CATH-2, D-CATH-2 and LL-37 can modulate the immune response of primary chicken immune cells by increasing mannose receptor expression, antigen presentation, endocytosis and neutralizing LPS-induced cytokine production and as a result augment activation of the adaptive immune system

Immunomodulation and effects on microbiota after in ovo administration of chicken cathelicidin-2

Host Defense Peptides (HDPs) such as cathelicidins are multifunctional effectors of the innate immune system with both antimicrobial and pleiotropic immunomodulatory functions. Chicken cathelicidin-2 (CATH-2) has multiple immunomodulatory effects in vitro and the D-amino acid analog of this peptide has been shown to partially protect young chicks from a bacterial infection. However, the mechanisms responsible for CATH-2 mediated in vivo protection have not been investigated so far. In this study, D-CATH-2 was administered in ovo and the immune status and microbiota of the chicks were investigated at 7 days posthatch to elucidate the in vivo mechanisms of the peptide. In three consecutive studies, no effects on numbers and functions of immune cells were found and only small changes were seen in gene expression of Peripheral Blood Mononuclear Cells (PBMCs). In two studies, intestinal microbiota composition was determined which was highly variable, suggesting that it was strongly influenced by environmental factors. In both studies, in ovo D-CATH-2 treatment caused significant reduction of Ruminococcaceae and Butyricicoccus in the cecum and Escherichia/Shigella in both ileum and cecum. In conclusion, this study shows that, in the absence of an infectious stimulus, in ovo administration of a CATH-2 analog alters the microbiota composition but does not affect the chicks' immune system posthatch

Immunomodulation and effects on microbiota after <i>in ovo</i> administration of chicken cathelicidin-2

<div><p>Host Defense Peptides (HDPs) such as cathelicidins are multifunctional effectors of the innate immune system with both antimicrobial and pleiotropic immunomodulatory functions. Chicken cathelicidin-2 (CATH-2) has multiple immunomodulatory effects <i>in vitro</i> and the D-amino acid analog of this peptide has been shown to partially protect young chicks from a bacterial infection. However, the mechanisms responsible for CATH-2 mediated <i>in vivo</i> protection have not been investigated so far. In this study, D-CATH-2 was administered <i>in ovo</i> and the immune status and microbiota of the chicks were investigated at 7 days posthatch to elucidate the <i>in vivo</i> mechanisms of the peptide. In three consecutive studies, no effects on numbers and functions of immune cells were found and only small changes were seen in gene expression of Peripheral Blood Mononuclear Cells (PBMCs). In two studies, intestinal microbiota composition was determined which was highly variable, suggesting that it was strongly influenced by environmental factors. In both studies, <i>in ovo</i> D-CATH-2 treatment caused significant reduction of Ruminococcaceae and <i>Butyricicoccus</i> in the cecum and <i>Escherichia/Shigella</i> in both ileum and cecum. In conclusion, this study shows that, in the absence of an infectious stimulus, <i>in ovo</i> administration of a CATH-2 analog alters the microbiota composition but does not affect the chicks’ immune system posthatch.</p></div

Chicken CATH-2 increases antigen presentation markers on chicken monocytes and macrophages

BACKGROUND: Cathelicidins are a family of Host Defense Peptides (HDPs), that play an important role in the innate immune response. They exert both broad-spectrum antimicrobial activity against pathogens, and strong immunomodulatory functions that affect the response of innate and adaptive immune cells Objective: The aim of this study was to investigate immunomodulation by the chicken cathelicidin CATH-2 and compare its activities to those of the human cathelicidin LL-37. METHOD: Chicken macrophages and chicken monocytes were incubated with cathelicidins. Activation of immune cells was determined by measuring surface markers Mannose Receptor C-type 1(MRC1) and MHCII. Cytokine production was measured by qPCR and nitric oxide production was determined using the Griess assay. Finally the effect of cathelicidins on phagocytosis was measured using carboxylate- modified polystyrene latex beads Results: CATH-2 and its all-D enantiomer D-CATH-2 increased MRC1 and MHC-II expression, markers for antigen presentation, on primary chicken monocytes, whereas LL-37 did not. D-CATH-2 also increased the MRC1 and MHC-II expression if a chicken macrophage cell line (HD11 cells) was used. In addition, LPS-induced NO production by HD11 cells was inhibited by CATH-2 and D-CATH-2 Conclusion: These results are a clear indication that CATH-2 (and D-CATH-2) affect the activation state of monocytes and macrophages, which leads to optimization of the innate immune response and enhancement of the adaptive immune response

Leukocyte populations in peripheral blood.

<p>Data from three repeated experiments. (a)-(b) total leukocytes (CD45), (c)-(d) mononuclear phagocytes (KUL01), (e)-(f) T-cells (CD3), (g) B-cells (Bu-1), (h) thrombocytes (CD41/CD6). Depicted are mean percentages of total cells (a,c,e,g,h) or mean absolute cell numbers (b,d,f) ± s.d., n = 6-8/group. Data of independent experiments were analyzed by an unpaired <i>t</i>-test, while combined data were analyzed using a General Linear Model.</p

PBMC functions measured by <i>ex vivo</i> assays.

<p>(a) Phagocytosis measured by uptake of pHrodo Green labelled <i>E</i>. <i>coli</i>. Increase in fluorescence from 1–6 hours of incubation. Data from three repeated experiments, (b) Oxidative burst measured by conversion of DCFH-DA to fluorescent DCF. Increase in fluorescence in 3 hours of incubation. Data from three repeated experiments, (c) Proliferation of responder PBMCs measured by MLR, Samples from Exp I, R = responder cells alone. Depicted are mean ± s.d., n = 5-8/group, ** = p<0.01. Data from independent experiments were analyzed by an unpaired <i>t</i>-test, combined phagocytosis and oxidative burst data were analyzed by a General Linear Model.</p