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Abstract: Quinoline-3-carboxamides (Q-compounds) are currently in clinical development for both autoimmune disease and cancer. We have previously shown that the Q-compound paquinimod (ABR-215757) significantly ameliorates disease symptoms in several mouse models of human inflammatory disease. Considering that recruitment of inflammatory cells into tissue is a common denominator of these models, we have in this report investigated whether paquinimod would interfere with cell accumulation during sterile peritoneal inflammation. To mimic the cell recruitment elicited by tissue injury, we used necrotic cells to induce the acute inflammatory response. We show that per oral treatment with paquinimod significantly reduced the accumulation of Ly6Chi inflammatory monocytes and eosinophils, but not neutrophils, in this model, and that this correlated with reduced number of such cells also in the omentum. Treatment also reduced the accumulation of these cell populations at a subcutaneous site of inflammation. In alum-induced inflammation, however, neutrophils were the dominant cell population and paquinimod failed to reduce the accumulation of inflammatory cells. Taken together, our results indicate that paquinimod selectively inhibits cell recruitment during acute sterile inflammation, but that this effect is context-dependent. These data have important implications for the understanding of the mechanism of action of Q-compounds in both pre-clinical and clinical settings. [Copyright &y& Elsevier]

Abstract: Quinoline-3-carboxamides are currently in clinical development for treatment of both autoimmune disease and cancer. Carboxamides such as ABR-215757 (5757) have shown efficacy in several in vivo mouse models of human inflammatory autoimmune disease. Some microbial infections in mice cause GM-CSF dependent accumulation of dendritic cells expressing TNFα and inducible nitric oxide synthase (iNOS; Tip-DCs) in lymphoid organs. Functionally similar DCs develop in GM-CSF stimulated bone marrow (BM) cell cultures and offered an in vitro model that allowed us to study the impact of 5757 on cellular development of relevance for in vivo inflammatory conditions. We show in here that addition of 5757 to such cultures, in a dose-dependent way increased the frequency of DCs, while it reduced the frequency of Gr-1+ cells by inhibiting their proliferation. This effect was specific as the compound neither influenced DC development from myeloid progenitors, nor the development of granulocytes in G-CSF stimulated BM cell cultures. Importantly, we also show that 5757 treatment reduced the accumulation of Gr-1+ cells during inflammation in vivo. We therefore propose that this compound may ameliorate autoimmune disease by blocking proliferation of Gr-1+ cells during inflammation-induced mobilization of myeloid cells. [Copyright &y& Elsevier]

Abstract: The quinoline-3-carboxamide ABR-215757 (5757) is in clinical development for the treatment of human SLE and has shown efficacy in several mouse models of T cell-mediated inflammatory autoimmune disease. The goal of this study was to determine the impact of 5757 on steady state immune cells. We show that the number of splenic CD4 dendritic cells (DCs) was reduced in 5757-treated mice, while there was no effect on other splenic DC populations, on DCs in lymph nodes or on lymphocytes. This reduction was fully reversible and the kinetics of CD4 DC loss during exposure and recovery after withdrawal of treatment was identical. The loss of CD4 DCs was neither caused by reduced proliferation nor by increased apoptosis. CD4 DCs reside in the splenic marginal zone, but the loss of these cells did not influence other cell populations at this site. The similar kinetics of the decay and repopulation of the splenic CD4 DC compartment suggests that the reduced number of CD4 DC in 5757 treated mice may be a result of blockade of CD4 DC precursor development in the spleen and not of toxicity. Alternatively, induced emigration of CD4 DC to the periphery, or an interference with adherence of these cells in the spleen marginal zone, may also explain our data. [Copyright &y& Elsevier]

Abstract: We have previously reported that the C-Med 100® extract of the plant Uncaria tomentosa induces prolonged lymphocyte half life and hence increased spleen cell number in mice receiving the extract in their drinking water. Further, the extract induces cell proliferation arrest and inhibits activation of the transcriptional regulator nuclear factor κB (NF-κB) in vitro. We now report that mice exposed to quinic acid (QA), a component of this extract, had significantly increased number of spleen cells, thus recapitulating the in vivo biological effect of C-Med 100® exposure. Commercially supplied QA (H+ form) did not, however, inhibit cell proliferation in vitro, while the ammonia-treated QA (QAA) was a potent inhibitor. Both QA and QAA inhibited NF-κB activity in exposed cells at similar concentrations. Thus, our present data identify QA as a candidate component for both in vivo and in vitro biological effects of the C-Med 100® extract. [Copyright &y& Elsevier]

Previous reports have demonstrated that extracts of the plant Uncaria tomentosa inhibit tumor cell proliferation and inflammatory responses. We have confirmed that C-Med 100®, a hot water extract of this plant, inhibits tumor cell proliferation albeit with variable efficiency. We extend these findings by showing that this extract also inhibits proliferation of normal mouse T and B lymphocytes and that the inhibition is not caused by toxicity or by induction of apoptosis. Further, the extract did not interfere with IL-2 production nor IL-2 receptor signaling. Since there was no discrete cell cycle block in C-Med 100®-treated cells, we propose that retarded cell cycle progression caused the inhibition of proliferation. Collectively, these data suggested interference with a common pathway controlling cell growth and cell cycle progression. Indeed, we provide direct evidence that C-Med 100® inhibits nuclear factor κB (NF-κB) activity and propose that this at least partially causes the inhibition of proliferation. [Copyright &y& Elsevier]