NLRP3 inflammasome: a novel link between lipoproteins and atherosclerosis.

INTRODUCTION: Pattern recognition receptor-mediated signaling pathways have recently been elucidated to bridge the innate immune system and atherosclerosis. NLRP3 is a member of the NLR family. Upon activation, it initiates IL-1ß and IL-18 processing, a key step in the inflammatory process of atherosclerosis. MATERIAL AND METHODS: We used three different types of lipoproteins, ox-LDL, ox-HDL, and HDL, in Thp-1 at the concentration of 50 mg/l, 100 mg/l, and 150 mg/l respectively. Using real-time polymerase chain reaction and western blot, ELISA detected the expression of NLRP3 and downstream cytokines. NLRP3 siRNA was constructed to down-regulate expression of the NLRP3 gene via the RNA interference technique. 150 mg/l of ox-LDL, ox-HDL and HDL was added to the Thp-1 cell line respectively. We observed the changes in the expression of caspase-1, IL-1ß and IL-18 when the NLRP3 gene was down-regulated. RESULTS: Ox-LDL and ox-HDL addition not only increases the expression of NLRP3, but also activates the NLRP3 downstream cytokines and caspase-1 and induces IL-1ß and IL-18 secretion. Moreover, the effects of activation and induction are shown to have a dose-dependent manner. Expression of NLRP3 and its downstream inflammatory cytokines is reduced in the presence of HDL (p < 0.05). Furthermore, our data demonstrated that NLRP3 siRNA downregulates NLRP3 expression in mononuclear cells, thus leading to a dramatic reduction in the expression of caspase-1, IL-1ß and IL-18 (p < 0.05). CONCLUSIONS: The data suggest that activation of the NLRP3 inflammasome is a critical step in caspase-1 activation and IL-1ß and IL-18 secretion. Interference with the NLRP3 inflammasome can significantly inhibit the generation of cytokines, thus impeding the pathogenesis of inflammation.

Lornoxicam suppresses recurrent herpetic stromal keratitis through down-regulation of nuclear factor-kappaB: an experimental study in mice.

PURPOSE: We designed the current study to determine the protective effects of lornoxicam, a cyclooxygenase (COX) inhibitor, on recurrent herpetic stromal keratitis (HSK) and the nuclear factor-kappaB (NF-kappaB)-mediated mechanism in mice. METHODS: A corneal latent herpes simplex virus-1 (HSV-1) infected mouse model was established. Six weeks later, Ultraviolet B (UVB) irradiation induced the recurrence. Corneal swabs were obtained and cultured with indicator cells to determine shedding of the virus. Lornoxicam was administered intraperitoneally daily, beginning one day before irradiation and lasting for seven days. Saline-treated and mock-infected control groups were also studied at the same time. Development of corneal inflammation and opacity was scored. Immunohistochemical staining and an electrophoretic mobility shift assay were performed to evaluate the effect of lornoxicam on NF-kappaB activation in the corneal tissues. The levels of tumor necrosis factor-alpha (TNF-alpha) in the cornea were determined by an enzyme-linked immunosorbent assay (ELISA). RESULTS: HSV-1 reactivation induced stromal edema and opacification concomitantly with elevated activation of NF-kappaB and elevated production of TNF-alpha. Lornoxicam treatment significantly decreased the incidence of recurrent HSK, attenuated the corneal opacity scores, and also effectively suppressed both NF-kappaB activation and TNF-alpha expression in biological analysis. Histopathology examination revealed a reduced immunostaining positive cell density for NF-kappaB in the cornea from lornoxicam-treated mice as well as a diminished inflammatory response. CONCLUSIONS: Lornoxicam exerts protective effects against HSK, presumably through the down-regulation of NF-kappaB activation.