-
[show abstract]
[hide abstract]
ABSTRACT: Costimulation of murine macrophages with immune complexes (ICs) and TLR ligands leads to alternative activation. Studies on human myeloid cells, however, indicate that ICs induce an increased pro-inflammatory cytokine production. This study aimed to clarify the effect of ICs on the pro- versus anti-inflammatory profile of human polarized macrophages.
Monocytes isolated from peripheral blood of healthy donors were polarized for four days with IFN-γ, IL-4, IL-10, GM-CSF, M-CSF, or LPS, in the presence or absence of heat aggregated gamma-globulins (HAGGs). Phenotypic polarization markers were measured by flow cytometry. Polarized macrophages were stimulated with HAGGs or immobilized IgG alone or in combination with TLR ligands. TNF, IL-6, IL-10, IL-12, and IL-23 were measured by Luminex and/or RT-qPCR.
HAGGs did not modulate the phenotypic polarization and the cytokine production of macrophages. However, HAGGs significantly altered the TLR-induced cytokine production of all polarized macrophage subsets, with the exception of MΦ(IL-4). In particular, HAGGs consistently enhanced the TLR-induced IL-10 production in both classically and alternatively polarized macrophages (M1 and M2). The effect of HAGGs on TNF and IL-6 production was less pronounced and depended on the polarization status, while IL-23p19 and IL-12p35 expression was not affected. In contrast with HAGGs, immobilized IgG induced a strong upregulation of not only IL-10, but also TNF and IL-6.
HAGGs alone do not alter the phenotype and cytokine production of in vitro polarized human macrophages. In combination with TLR-ligands, however, HAGGs but not immobilized IgG shift the cytokine production of distinct macrophage subsets toward IL-10.
PLoS ONE 01/2012; 7(4):e35994. · 4.09 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The pathogenesis of psoriatic arthritis (PsA) remains poorly understood. The underlying chronic inflammatory immune response is thought to be triggered by unknown environmental factors potentially arising from a defective immune function. We undertook this study to determine whether an impaired acute inflammatory response by dendritic cells (DCs) might compromise the clearance of bacteria and predispose to chronic inflammation.
We determined cytokine production by DCs from healthy controls and from patients with rheumatoid arthritis, PsA, and psoriasis in response to Mycobacterium tuberculosis, Mycobacterium avium paratuberculosis, and a range of other bacteria and Toll-like receptor (TLR) ligands. Phenotypic differences involved in cellular responses against (myco)bacteria were determined by quantitative polymerase chain reaction and flow cytometry.
The secretion of proinflammatory cytokines by PsA DCs was impaired upon in vitro challenge with mycobacteria and TLR-2 ligands. This impairment was associated with elevated serum levels of C-reactive protein. The expression of TLR-2 and other receptors known to mediate mycobacterial recognition was unaltered. In contrast, the intracellular TLR inhibitors suppressor of cytokine signaling 3 and A20 were more highly expressed in DCs from PsA patients. PsA DCs further demonstrated up-regulated levels of ATG16L1, NADPH oxidase 2, and LL37, which are molecules implicated in the immune response against intracellular bacteria.
Our findings indicate that DCs from PsA patients have a disordered immune response toward some species of (myco)bacteria. This might predispose to impaired immune responses to, and in turn impaired clearance of, these bacteria, setting the stage for the chronic inflammation of joints, entheses, skin, and the gut.
Arthritis & Rheumatism 08/2011; 63(11):3313-22. · 7.87 Impact Factor
-
Mark H Wenink,
Kim C M Santegoets,
Jacobus C A Broen, Lenny van Bon,
Shahla Abdollahi-Roodsaz,
Calin Popa,
Richard Huijbens,
Thijs Remijn,
Erik Lubberts,
Piet L C M van Riel,
Wim B van den Berg,
Timothy R D J Radstake
[show abstract]
[hide abstract]
ABSTRACT: TLR2 plays an important role in the removal of Gram-positive bacteria; contrastingly, it also appears to have important protective effects against unrestrained inflammation and subsequent organ injury during infection and autoimmunity. We hypothesized that TLR2 tunes the phenotype of dendritic cells (DCs) activated through other TLRs, thereby fulfilling a crucial role in the modulation of the immune response. TLR2 potently inhibited TLR4- and TLR7/8-induced cytokine production by human DCs. The inhibitory effect of TLR2 on the release of TNF-alpha but not of IL-12p70 was mediated by PI3K. TLR2 inhibits the production of IL-12p70 by dampening the type 1 IFN amplification loop. When DCs were triggered with the potent synergistic combination of LPS (TLR4) and R848 (TLR7/8) in conjunction with a TLR2 ligand, a clear shift to more Th2- and Th17-prone responses in the naive and memory T cell subpopulations was observed. This shift in T cell responses was inherent to the inability of TLR2-stimulated DCs to produce IL-12p70 and was dependent on the production of IL-1 and IL-6.
The Journal of Immunology 11/2009; 183(11):6960-70. · 5.79 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Systemic sclerosis (SSc) is an autoimmune disease where controversy on Th1/Th2 balance dominates. We investigated whether the recently discovered Th17 pattern was present in SSc.
Patients were subdivided as having limited cutaneous SSc (lcSSc, n = 12) or diffuse cutaneous SSc (dcSSc, n = 24). A further arbitrary subdivision was made between early dcSSc (n = 11) and late dcSSc (n = 13) based upon the duration of disease. As a comparator group 14 healthy controls were studied. CD3+ cells were isolated using FACS and subsequently studied for the expression of CD4, CD8, CD25, CD45Ro, CD45Ra, IL-23, GITR, CD69 and intracellular expression of IL-17, TGFbeta and IFNgamma using flow cytometry. Levels of IL-17, IL-6, IL-1alpha and IL-23 were measured using Bioplex assays. SSc patients had more and more activated CD4+ cells. In addition, CD4, CD45Ro and CD45Ra cells from all SSc patients highly expressed the IL23R, which was associated with a higher IL-17 expression as well. In contrast, IFNgamma and TGFbeta were selectively up regulated in SSc subsets. In line with these observation, circulating levels of IL-17 inducing cytokines IL-6, IL-23 and IL-1alpha were increased in all or subsets of SSc patients.
The combination of IL-17, IFNgamma and TGFbeta levels in CD45Ro and CD45Ra cells from SSc patients is useful to distinguish between lSSc, ldSSc or edSSc. Blocking Th17 inducing cytokines such as IL-6 and IL-23 may provide a useful tool to intervene in the progression of SSc.
PLoS ONE 02/2009; 4(6):e5903. · 4.09 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Regulatory T cells (Tregs) are essential in the control of tolerance. Evidence implicates Tregs in human autoimmune conditions. Here we investigated their role in systemic sclerosis (SSc).
Patients were subdivided as having limited cutaneous SSc (lcSSc, n = 20) or diffuse cutaneous SSc (dcSSc, n = 48). Further subdivision was made between early dcSSc (n = 24) and late dcSSc (n = 24) based upon the duration of disease. 26 controls were studied for comparison. CD3+ cells were isolated using FACS and subsequently studied for the expression of CD4, CD8, CD25, FoxP3, CD127, CD62L, GITR, CD69 using flow cytometry. T cell suppression assays were performed using sorted CD4CD25(high)CD127(-) and CD4CD25(low)CD127(high) and CD3(+) cells. Suppressive function was correlated with CD69 surface expression and TGFbeta secretion/expression. The frequency of CD4(+)CD25(+) and CD25(high)FoxP3(high)CD127(neg) T cells was highly increased in all SSc subgroups. Although the expression of CD25 and GITR was comparable between groups, expression of CD62L and CD69 was dramatically lower in SSc patients, which correlated with a diminished suppressive function. Co-incubation of Tregs from healthy donors with plasma from SSc patients fully abrogated suppressive activity. Activation of Tregs from healthy donors or SSc patients with PHA significantly up regulated CD69 expression that could be inhibited by SSc plasma.
These results indicate that soluble factors in SSc plasma inhibit Treg function specifically that is associated with altered Treg CD69 and TGFbeta expression. These data suggest that a defective Treg function may underlie the immune dysfunction in systemic sclerosis.
PLoS ONE 02/2009; 4(6):e5981. · 4.09 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Antigen-presenting cells (APCs) play an important role in the development of autoimmune diseases. These cells recognize pathogen associated molecular patterns but also endogenously produced ligands through toll-like receptors (TLRs). Aberrant activation of these receptors and the following intracellular signaling pathways can induce the deleteri-ous production of pro-inflammatory cytokines. In genetically predisposed individuals this might lead to a breach in toler-ance and eventually autoimmunity. IgG and IgG immune complexes (ICs), which are abundantly present in autoimmune diseases like systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and systemic sclerosis (SSc) are recognized by APCs via Fc gamma receptors (FcRs) and can also modulate their activation state. Upon their uptake specific antigens present in ICs are capable of stimulating APCs via their intracellular TLRs, increasing their capability to induce (autoreac-tive) T and B cell responses. This underscores their likely role in the generation and maintenance of autoimmunity. By fo-cusing on three autoimmune diseases, SLE, RA and SSc, we will illustrate the importance of TLRs and FcRs in the pathogenesis of autoimmune diseases.
