Guo-Min Deng

Cholera Toxin B Accelerates Disease Progression in Lupus-Prone Mice by Promoting Lipid Raft Aggregation

Infectious agents, including bacteria and viruses, are thought to provide triggers for the development or exacerbation of autoimmune diseases such as systemic lupus erythematosus in the genetically predisposed individual. Molecular mimicry and engagement of TLRs have been assigned limited roles that link infection to autoimmunity, but additional mechanisms are suspected to be involved. In this study we show that T cells from lupus-prone mice display aggregated lipid rafts that harbor signaling, costimulatory, inflammatory, adhesion, and TLR molecules. The percentage of T cells with clustered lipid rafts increases with age and peaks before the development of lupus pathology. We show that cholera toxin B, a component of Vibrio cholerae, promotes autoantibody production and glomerulonephritis in lupus-prone mice by enhancing lipid raft aggregation in T cells. In contrast, disruption of lipid raft aggregation results in delay of disease pathology. Our results demonstrate that lipid rafts contribute significantly to the pathogenesis of lupus and provide a novel mechanism whereby aggregated lipid rafts represent a potential link between infection and autoimmunity.

Targeted Tumor Necrosis Factor Receptor I Preligand Assembly Domain Improves Skin Lesions in MRL/lpr Mice

OBJECTIVE Skin disease is the second most common manifestation in patients with systemic lupus erythematosus (SLE). Tumor necrosis factor receptor (TNFR) preligand assembly domain (PLAD) has been found to block the effect of TNFalpha, and TNFRI PLAD (p60 PLAD) inhibits inflammatory arthritis. This study was undertaken to investigate whether TNFR PLAD limits inflammatory skin injury in a mouse model of SLE. METHODS Female MRL/lpr mice received p60 PLAD (100 microg/mouse intraperitoneally), p80 PLAD (100 microg/mouse intraperitoneally), or phosphate buffered saline (100 microl/mouse intraperitoneally) 3 times a week for 26 weeks, starting at age 6 weeks. RESULTS Immunohistochemistry studies demonstrated that TNFRI but not TNFRII was dominantly expressed in skin lesions in MRL/lpr mice. We found that TNFRI PLAD (p60 PLAD) but not TNFRII PLAD (p80 PLAD) protein significantly inhibited skin injury in the MRL/lpr mouse model of lupus. NF-kappaB, monocyte chemotactic protein 1, and inducible nitric oxide synthase expression in skin lesions were significantly inhibited by p60 PLAD. Lupus serum-induced monocyte differentiation into dendritic cells was reduced by p60 PLAD, but p60 PLAD did not reduce IgG deposition in the skin or improve the progression of kidney damage in MRL/lpr mice. CONCLUSION Our results indicate that TNFRI is involved in the expression of skin injury in MRL/lpr mice with lupus and that p60 PLAD or similar biologics may be of clinical value if applied locally.

Lupus Serum IgG Induces Skin Inflammation through the TNFR1 Signaling Pathway

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by high autoantibody levels and multiorgan tissue damage, including kidney and skin. Cutaneous manifestations are frequent in patients with SLE, yet the etiology and pathogenesis of skin injury in SLE remains unclear. We reasoned that lupus serum containing high levels of autoreactive Ig contributes to skin injury. In this article, we report that serum from SLE patients and lupus-prone mice induces skin inflammation following intradermal injection into normal mice. Lupus serum depleted of IgG failed to cause skin inflammation. Monocytes, but not lymphocytes, were found to be crucial in the development of lupus serum-induced skin inflammation, and lupus serum IgG induced monocyte differentiation into dendritic cells (DCs). TNF-α and TNFR1, but not TNFR2, were required for the development of lupus serum-induced skin inflammation. TNFR1, not TNFR2, represented the main molecule expressed in the skin lesions caused by injected lupus serum. Our studies demonstrated that lupus serum IgG causes skin injury by involving the TNFR1 signaling pathway and monocyte differentiation to DCs. Accordingly, disruption of the TNFR1-mediated signaling pathway and blockade of DC generation may prove to be of therapeutic value in patients with cutaneous lupus erythematosus.

Pathogenesis and targeted treatment of skin injury in SLE

Skin is the second most common organ (after the kidney) to be affected in patients with systemic lupus erythematosus (SLE), yet the aetiology of skin injury and the mechanisms involved in the development of dermal manifestations of SLE remain unclear. Ultraviolet light (UV), immune cells, cytokines and deposition of immunoglobulins all seem to have a role in the development of skin inflammation and damage in SLE. UV represents the most important environmental factor, and exposure to UV triggers the development of skin lesions in areas where immunoglobulin has been deposited and various other components of the immune system have accumulated. In addition, a number of intracellular kinases and transcription factors have also been demonstrated to be involved in the generation of skin lesions in lupus-prone mice. These molecules can be targeted by small-molecule inhibitors, leading to the prospect that treatments suitable for topical application, and with limited adverse effects, could be developed. Further studies to eliminate the burden of skin inflammation in patients with SLE are clearly required.

Ischemia-mediated aggregation of the actin cytoskeleton is one of the major initial events resulting in ischemia-reperfusion injury

Ischemia-reperfusion (IR) injury represents a major clinical challenge, which contributes to morbidity and mortality during surgery. The critical role of natural immunoglobulin M (IgM) and complement in tissue injury has been demonstrated. However, cellular mechanisms that result in the deposition of natural IgM and the activation of complement are still unclear. In this report, using a murine intestinal IR injury model, we demonstrated that the beta-actin protein in the small intestine was cleaved and actin filaments in the columnar epithelial cells were aggregated after a transient disruption during 30 min of ischemia. Ischemia also led to deposition of natural IgM and complement 3 (C3). A low dose of cytochalasin D, a depolymerization reagent of the actin cytoskeleton, attenuated this deposition and also attenuated intestinal tissue injury in a dose-dependent manner. In contrast, high doses of cytochalasin D failed to worsen the injury. These data indicate that ischemia-mediated aggregation of the actin cytoskeleton, rather than its disruption, results directly in the deposition of natural IgM and C3. We conclude that ischemia-mediated aggregation of the actin cytoskeleton leads to the deposition of natural IgM and the activation of complement, as well as tissue injury.

Targeting Syk in Autoimmune Rheumatic Diseases

Spleen tyrosine kinase (Syk) is a member of the Src family of non-receptor tyrosine kinases, which associates directly with surface receptors, including B-cell receptor and Fcγ receptor, and is involved in a variety of signal transduction pathways. Rheumatoid arthritis (RA) and systemic lupus erythematosus are autoimmune diseases in which autoantibodies, immune complexes, and autoreactive T cells account for the expression of tissue inflammation and damage. Syk inhibitors efficiently suppress RA in patients albeit in the expression of unwanted side effects, including gastrointestinal effects, hypertension, and neutropenia. Syk inhibitors also inhibit clinical manifestations in lupus-prone mice. Here, we review the evidence that supports the use of Syk inhibitors to treat rheumatic and other autoimmune diseases.

T Cell CD3ζ Deficiency Enables Multiorgan Tissue Inflammation

Although a population of T cells with CD3ζ chain deficiency has been found in patients with systemic lupus erythematosus, rheumatoid arthritis, cancer, and infectious disease, the role of CD3ζ chain in the disease pathogenesis remains unknown. To understand the contribution of CD3ζ deficiency to the expression of organ injury, we have performed the following studies. We used CD3ζ-deficient mice to investigate the role of CD3ζ in the pathogenesis of organ tissue inflammation. We found that the CD3ζ−/− mice can spontaneously develop significant organ inflammation that can be accelerated following the administration of polyinosinic:polycytidylic acid or allogeneic cells (graft versus host). T cells from CD3ζ−/− mice display increased expression of the adhesion molecules CD44 and CCR2 and produce increased amounts of IFN-γ blockade, which mitigates tissue inflammation. Our results demonstrate that CD3ζ deficiency bestows T cells with the ability to infiltrate various tissues and instigate inflammation. Decreased CD3ζ expression noted in T cells from various diseases contributes independently to tissue inflammation and organ damage. Approaches to restore CD3ζ expression of the surface of T cells should be expected to mitigate tissue inflammation.

Skin inflammation induced by lupus serum was inhibited in IL-1R deficient mice

Skin inflammation induced by lupus serum is a useful tool to investigate the pathogenesis of lupus skin injury. IL-1 is a proinflammatory cytokine, and its role in lupus skin lesion is still unclear. We determined the role of IL-1 in lupus skin injury by using gene deficient mice. We found that skin inflammation induced by lupus serum was significantly reduced in IL-1R deficient mice and caspase-1 deficient mice. IL-1R deficiency did not affect the expression of FcγRI (CD64), FcγRII (CD32) and MHC class II (CD74) induced by lupus serum. IL-1R deficiency reduced the lipid raft clustering, and decreased expression of MCP-1 and TNFα in monocytes. Keratinocyte proliferation induced by lupus serum was significantly decreased in TNFα deficient mice. Our findings indicate that IL-1 plays an important role in skin lesions of SLE. This study suggests that IL-1 is a therapeutic target in skin lesions of SLE.

339 The role of neutrophils in organ tissue damage in sle

Background and aims Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterised by high levels of autoantibodies and multi-organ damage. Neutrophils are the most abundant leukocytes in Human blood, but it is not clear whether neutrophils exert an important role in the pathogenesis of organ tissue damage in SLE. Methods We used lupus-prone mouse model and model of lupus serum-induced tissue inflammation in mouse to investigate the role of neutrophils in the organ damage of SLE. Results We found that there was a little neutrophil infiltration in the inflammatory sites of skin, liver, brain and joint in lupus-prone mice. We also found that there was also little neutrophil infiltration in the site of skin inflammation induced by lupus serum in normal mouse. The severity of skin inflammation induced by lupus serum was not significantly decreased in mice with neutrophil depletion compared to ones without neutrophil depletion. But we found that neutrophils were actually involved in tissue injury induced by lupus IgG. Further studies showed that lupus IgG stimulated and activated neutrophils, and cause the death of neutrophils. Studies also confirmed that Fas plays an important role in neutrophils apoptosis. Conclusions Our study indicates that neutrophils participate in the early stage of lupus organ damage, and then they died through activation-mediated apoptosis. These findings promote the understanding of the role of neutrophils in the tissue injury with SLE.

210 Oestrogen promotes sle serum igg-induced skin inflammation via the oestrogen membrane receptor gper1

Background and aims Skin injury is the second most common clinical manifestation in patients with systemic lupus erythematosus (SLE). Oestrogen may affect the onset and development of SLE. This study was undertaken to elucidate the role of oestrogen in the development of SLE skin injury. Methods We investigated the role of oestrogen and its membrane receptor GPER1 in SLE-related skin injury in mice treated with SLE serum in vivo, and monocytes from mouse spleen in vitro. Results We found that skin injury induced by SLE serum was more severe in female mice and required monocytes. E2 promoted these effects through the membrane receptor GPER1 located in lipid rafts and that inhibition of lipid rafts and GPER1 suppressed SLE serum-induced skin inflammation and expression of inflammatory molecules. Conclusions We conclude that oestrogen promotes the development of skin injury induced by SLE serum through the membrane receptor GPER1 and that lipid rafts play an important role in the regulatory effect of GPER1 in SLE skin inflammation.