ABSTRACT
Systemic sclerosis (SSc) is an intractable autoimmune disease characterized by vasculopathy and organ fibrosis. Autologous hematopoietic stem cell transplantation (AHSCT) should be considered for the treatment of selected patients with rapid progressive SSc at high risk of organ failure. It, however, remains elusive whether immunosuppressive therapies such as rituximab (RTX) are still necessary for such patients after AHSCT, especially in those with bad outcomes. In the present report, a 43-year-old man with diffuse cutaneous SSc received AHSCT. Despite AHSCT, SSc further progressed with progressive symptomatic heart failure with newly developed concomitant mitral and tricuspid valve insufficiency, thus the patient started on RTX 8 months after AHSCT. Shortly after initiation of RTX, clinical symptoms and organ functions ameliorated subsequently. Heart valve regurgitations were reversible after initiation of RTX treatment. Currently, the patient remains in a stable condition with significant improvement of clinical symptoms and organ functions. Reporting about therapies after AHSCT in SSc is a very important issue, as randomized controlled trials are lacking, and therefore this report adds to evidence that RTX can be considered as a treatment option in patients with SSc that do not respond to AHSCT.
ABSTRACT
OBJECTIVE: The lipid mediator sphingosine 1-phosphate (S1P) is found in the synovial fluid of osteoarthritis (OA) patients. S1P protects bovine cartilage by counteracting the effects of interleukin-1ß (IL-1ß). This study was undertaken to examine the interaction of S1P and IL-1ß in human OA chondrocytes. METHODS: Human cartilage was obtained from patients undergoing total knee joint replacement. Chondrocytes were cultured in monolayer and treated with IL-1ß and S1P. Expression of S1P receptor subtypes and genes involved in cartilage degradation was evaluated using real-time polymerase chain reaction, immunohistochemistry, and Western blotting. S1P signaling was evaluated using inhibitors of S1P receptors and small interfering RNA (siRNA) knockdown of the S1P2 receptor. Phosphorylation of MAP kinases and NF-κB in response to IL-1ß and S1P was detected by Western blotting. RESULTS: S1P2 was identified as the most prevalent S1P receptor subtype in human OA cartilage and chondrocytes in vitro. S1P reduced expression of inducible nitric oxide synthase (iNOS) in IL-1ß-treated chondrocytes. Reduction of ADAMTS-4 and matrix metalloproteinase 13 expression by S1P correlated with S1P2 expression. Pharmacologic inhibition of the S1P2 receptor, but not the S1P1 and S1P3 receptors, abrogated the inhibition of iNOS expression. Similar results were observed using siRNA knockdown. S1P signaling inhibited IL-1ß-induced phosphorylation of p38 MAPK. CONCLUSION: In human chondrocytes, S1P reduces the induction of catabolic genes in the presence of IL-1ß. Activation of the S1P2 receptor counteracts the detrimental phosphorylation of p38 MAPK by IL-1ß.
