CD19, a response regulator of B lymphocytes, regulates wound healing through hyaluronan-induced TLR4 signaling.

Immune cells are critical to the wound-healing process, through both cytokine and growth factor secretion. Although previous studies have revealed that B cells are present within wound tissue, little is known about the role of B cells in wound healing. To clarify this, we investigated cutaneous wound healing in mice either lacking or overexpressing CD19, a critical positive-response regulator of B cells. CD19 deficiency inhibited wound healing, infiltration of neutrophils and macrophages, and cytokine expression, including basic and acidic fibroblast growth factor, interleukin-6, platelet-derived growth factor, and transforming growth factor-beta. By contrast, CD19 overexpression enhanced wound healing and cytokine expression. Hyaluronan (HA), an endogenous ligand for toll-like receptor (TLR)-4, stimulated B cells, which infiltrates into wounds to produce interleukin-6 and transforming growth factor-beta through TLR4 in a CD19-dependent manner. CD19 expression regulated TLR4 signaling through p38 activation. HA accumulation was increased in injured skin tissue relative to normal skin, and exogenous application of HA promoted wound repair in wild-type but not CD19-deficient mice, suggesting that the beneficial effects of HA to the wound-healing process are CD19-dependent. Collectively, these results suggest that increased HA accumulation in injured skin induces cytokine production by stimulating B cells through TLR4 in a CD19-dependent manner. Thus, this study is the first to reveal a critical role of B cells and novel mechanisms in wound healing.

Endothelial selectins regulate skin wound healing in cooperation with L-selectin and ICAM-1.

Skin wound healing is mediated by inflammatory cell infiltration that is highly regulated by various adhesion molecules. Mice lacking intercellular adhesion molecule-1 (ICAM-1) delayed skin wound healing and mice lacking both L-selectin and ICAM-1 (L-selectin/ICAM-1(-/-)) show more delayed wound healing. Deficiency of both endothelial selectins (E-selectin or P-selectin) also delays wound healing. However, the relative contribution and interaction of selectins and ICAM-1 to the wound healing remain unknown. To clarify them, repair of excisional wounds was examined in L-selectin/ICAM-1(-/-) mice, wild-type mice with both E- and P-selectin blockade, and L-selectin/ICAM-1(-/-) mice with both E- and P-selectin blockade. Wild-type mice with both E- and P-selectin blockade showed delayed wound healing that was comparable with that in L-selectin/ICAM-1(-/-) mice. Combined E- and P-selectin blockade in L-selectin/ICAM-1(-/-) mice resulted in more significant delay. Mice lacking or blocked for adhesion molecules also showed suppressed keratinocyte migration, angiogenesis, granulation tissue formation, leukocyte infiltration, and cytokine expression, including transforming growth factor-beta and interleukin-6. Application of basic fibroblast growth factor (bFGF) but not platelet-derived growth factor to the wounds significantly improved wound healing in L-selectin/ICAM-1(-/-) mice with both E- and P-selectin blockade. bFGF significantly increased the leukocyte infiltration and subsequent fibrogenic cytokine production, as well as keratinocyte migration, angiogenesis, and collagen synthesis despite the loss of four kinds of adhesion molecules. These results indicate that skin wound healing is regulated cooperatively by all selectins and ICAM-1 and may provide critical information for the therapy of skin wounds.

Drug-induced hypersensitivity syndrome associated with human herpesvirus 6 and cytomegalovirus reactivation.

We describe a patient with drug-induced hypersensitivity syndrome (DIHS) associated with human herpesvirus 6 (HHV-6) and cytomegalovirus (CMV) infection induced by sulfasalazine. Two weeks after starting sulfasalazine to treat a rectal ulcer, the patient developed disseminated macular erythema accompanied by fever, liver injury, and lymphadenopathy. Seroconversion of antibodies to HHV-6 was observed. Systemic steroid treatment was not effective against the eruptions. Five months after the onset, he presented with an acute febrile disease. The detection of CMV antigen on peripheral blood leukocytes and positive staining for CMV on cutaneous endothelium indicated active CMV infection. Furthermore, he developed a bacteremia of methicillin resistant Staphylococcus aureus. An association the CMV reactivation with DIHS was suggested, although there remains the possibility that the systemic steroid treatment precipitated CMV reactivation. Recently, HHV-6 has been documented to have immunomodulating effects and to be associated with CMV reactivation. Therefore, we should pay attention to the possibility of CMV reactivation in patients with DIHS in whom the immunomodulating virus of HHV-6 has been reactivated.

Increased serum soluble OX40 in patients with systemic sclerosis.

OBJECTIVE: To determine levels of serum soluble OX40 (also termed CD134, a member of the tumor necrosis factor receptor superfamily) and their clinical associations in patients with systemic sclerosis (SSc). METHODS: Serum soluble OX40 levels were examined by ELISA in 53 patients with SSc, 15 patients with systemic lupus erythematosus (SLE), and 32 healthy individuals. RESULTS: OX40 levels were significantly elevated in SSc patients (125.7 +/- 5.7 pg/ml) compared to patients with SLE (80.7 +/- 1.7 pg/ml; p < 0.005) and controls (88.2 +/- 3.0 pg/ml; p < 0.0001). Elevated OX40 levels were found to be associated with disease duration of less than 2 years (p < 0.05). CONCLUSION: Our results suggest that serum soluble OX40 levels correlate with the early-onset of SSc disease.