RESUMEN
Discoid lupus erythematous (DLE) is a common autoimmune skin disorder of dogs where keratinocytes play a pivotal role both in the innate and adaptive immune responses. As for the innate response, pattern recognition receptors (PRR), including Toll-like receptors (TLRs), can activate macrophages and immune tissue cells allowing for transmission and transduction of signals through cytokine and chemokine release to improve host defenses. In particular, TLR4 can also recognize endogenous molecules such as heat shock proteins produced during reactions to tissue damage. The aim of this study was to evaluate the expression of TLR4, a bacterial lipopolysaccharide sensor, in the skin of dogs with DLE and in normal skin to evaluate a possible involvement of this receptor in the disease pathogenesis. Skin samples of affected dogs had a diffuse and intense expression of TLR4 in the epidermis. Also, the inflammatory infiltrates were immunolabelled. The expression was significantly higher in DLE skin compared to normal skin (**** p < 0.0001). In conclusion, dogs with DLE showed an altered expression of TLR4, which might play an important pathogenic role in the ongoing immunopathologic process, thus being considered a valuable therapeutic potential target for DLE.
RESUMEN
Bortezomib, a proteasome inhibitor with efficacy in multiple myeloma, is associated with thrombocytopenia, the cause and kinetics of which are different from those of standard cytotoxic agents. We assessed the frequency, kinetics, and mechanism of thrombocytopenia following treatment with bortezomib 1.3 mg/m2 in 228 patients with relapsed and/or refractory myeloma in 2 phase 2 trials. The mean platelet count decreased by approximately 60% during treatment but recovered rapidly between treatments in a cyclic fashion. Among responders, the pretreatment platelet count increased significantly during subsequent cycles of therapy. The mean percent reduction in platelets was independent of baseline platelet count, M-protein concentration, and marrow plasmacytosis. Plasma thrombopoietin levels inversely correlated with platelet count. Murine studies demonstrated a reduction in peripheral platelet count following a single bortezomib dose without negative effects on megakaryocytic cellularity, ploidy, or morphology. These data suggest that bortezomib-induced thrombocytopenia is due to a reversible effect on megakaryocytic function rather than a direct cytotoxic effect on megakaryocytes or their progenitors. The exact mechanism underlying bortezomib-induced thrombocytopenia remains unknown but it is unlikely to be related to marrow injury or decreased thrombopoietin production.
