Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenase-1 (COX-1) and COX-2 enzymes. The NLRP3 inflammasome is a multi-protein complex responsible for the processing of the proinflammatory cytokine interleukin-1β and is implicated in many inflammatory diseases. Here we show that several clinically approved and widely used NSAIDs of the fenamate class are effective and selective inhibitors of the NLRP3 inflammasome via inhibition of the volume-regulated anion channel in macrophages, independently of COX enzymes. Flufenamic acid and mefenamic acid are efficacious in NLRP3-dependent rodent models of inflammation in air pouch and peritoneum. We also show therapeutic effects of fenamates using a model of amyloid beta induced memory loss and a transgenic mouse model of Alzheimer's disease. These data suggest that fenamate NSAIDs could be repurposed as NLRP3 inflammasome inhibitors and Alzheimer's disease therapeutics.

Migration of microglial cells towards damaged tissue plays a key role in central nervous system regeneration under pathological conditions. Using time lapse video microscopy we show that lysophosphatidic acid (LPA) enhances chemokinetic migration of murine microglial cells. In the presence of 1 micro m LPA, the mean migration rate of microglial cells was increased 3.8-fold. In patch-clamp studies we demonstrate that LPA induces activation of a Ca(2+)-activated K(+) current. Microglial Ca(2+)-activated K(+) currents were abolished by either 50 nm charybdotoxin or 10 micro m clotrimazole. In contrast, 5 micro m paxilline did not have any significant effects on Ca(2+)-activated K(+) currents. The LPA-stimulated migration of microglial cells was inhibited by blockers of IKCa1 Ca(2+)-activated K(+) channels. The mean migration rate of LPA-stimulated cells was decreased by 61% in the presence of 50 nm charybdotoxin or by 51% during exposure to 10 micro m clotrimazole. Microglial migration was not inhibited by 5 micro m paxilline. It is concluded that IKCa1 Ca(2+)-activated K(+) channels are required for LPA-stimulated migration of microglial cells.

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Journal of PhysiologyJurkat cells (Benichou et al. 1989;Gulbins et al. 1996), but sparingly expressed in T lymphocytes which lack this capability (van Reyk et al. 2001). We show here that the levels of H + channel expression in human B lymphocytes and in Jurkat cells are quantitatively more than adequate to sustain NADPH oxidase activity in these cells. METHODS CellsJurkat T cells. The human T leukaemia cell line Jurkat E6-1 was obtained from DSMZ (Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Braunschweig, Germany). Jurkat T cells were grown in RPMI 1640 medium (GibcoBRL, Eggenstein, Germany) supplemented with 10 % fetal bovine serum and 2 mM glutamine at densities of 1-9 w 10 5 in a 37°C humidified incubator with 5 % CO 2 , and split three times weekly.Human lymphocytes. Venous blood was drawn from healthy adult volunteers after informed written consent was obtained according to procedures approved by the local Institutional Review Board and in accordance with Federal regulations. Lymphocytes were obtained from the whole blood of the donors. The suspension was layered on top of ficoll-hypaque (AmershamPharmarcia, Freiburg, Germany) after dilution with an equal volume of RPMI 1640 (GibcoBRL, Eggenstein, Germany). After centrifugation (30 min, 500 g, room temperature), mononuclear cells were harvested from the interphase, washed twice with lowspeed centrifugation (200 g, 10 min, 20°C) to remove platelets, and resuspended at 1.5 w 10 8 ml _1 in degassed RPMI1640 containing 0.5 % bovine serum albumin and 2 mM EDTA. B cells were separated by negative depletion using the MACS B cell isolation kit (Miltenyi Biotec, Bergisch Gladbach, Germany) following the manufacturer's instructions. Briefly, after blocking Fc receptors with aggregated human immunoglobulin, cells were incubated with murine hapten-conjugated monoclonal antibodies directed against human CD2, CD4, CD11b, CD16, CD36 and anti-IgE at 10°C for 10 min, washed twice, and then incubated with anti-hapten microbeads at 10°C for 15 min. The washed cell suspension was then placed on a LS+/VS+ column (Miltenyi), and the unlabelled cells passing through were collected from the effluent. This fraction consisted of 97 % CD19+ cells, as judged by flow cytometry after staining with fluoresceinisothiocyanate-conjugated Leu-12 monoclonal antibody (Becton Dickinson, Heidelberg, Germany). Subsequently, the LS+/VS+ column was placed outside the magnetic field, and the retained cells were eluted. This B cell-depleted fraction contained 80-90 % of CD3+ cells as judged by flow cytometry after staining with fluoresceinisothiocyanate-conjugated anti-CD3 monoclonal antibody (Dako, Hamburg, Germany).

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