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Inhibitors of serine peptidases (ISPs) expressed by Leishmania major enhance intracellular parasitism in macrophages by targeting neutrophil elastase (NE), a serine protease that couples phagocytosis to the prooxidative TLR4/PKR pathway. Here we investigated the functional interplay between ISP-expressing L. major and the kallikrein-kinin system (KKS). Enzymatic assays showed that NE inhibitor or recombinant ISP-2 inhibited KKS activation in human plasma activated by dextran sulfate. Intravital microscopy in the hamster cheek pouch showed that topically applied L. major promastigotes (WT and Δis2/3 mutants) potently induced plasma leakage through the activation of bradykinin B2 receptors (B2R).Next, usingmAbs against kininogen domains, we showed that these BK-precursor proteins are sequestered by L. major promastigotes, being expressed at higher % in the Δis2/3 mutant population. Strikingly, analysis of the role of kinin pathway in the phagocytic uptake of L. major revealed that antagonists of B2Ror B1R reversed the upregulated uptake of Δis2/3mutants without inhibiting macrophage internalization ofWT L. major. Collectively, our results suggest that L. major ISP-2 fine-tunes macrophage phagocytosis by inhibiting the pericellular release of proinflammatory kinins from surface bound kininogens. Ongoing studies should clarify whether L. major ISP-2 subvertsTLR4/PKR-dependent prooxidative responses of macrophages by preventing activation of G-protein coupled B2R/B1R. [ABSTRACT FROM AUTHOR]

Chronic chagasic myocarditis (CCM) dependson Trypanosoma cruzi persistence in the myocardium. Studies of the proteolytic mechanisms governing host/parasitebalance inperipheralsites of T. cruzi infection revealed that tissue culturetrypomastigotes (TCTs) elicit inflammatory edema and stimulateprotective type-1 effector T cells through the activation of the kallikrein-kininsystem. Molecular studies linked the proinflammatory phenotype of Dm28c TCTs to the synergisticactivities of tGPI, alipidanchor that functions as a Toll-like receptor 2(TLR2) ligand, and cruzipain, akinin-releas in gcysteineprotease. Analysis of the dynamics of inflammation revealed that TCTs activate in natesentinelcellsvia TLR2, releasing CXC chemokines, which in turnevokeneutrophil/CXCR2-dependent extravasation of plasmaproteins, including high molecular weight kininogen (HK), inparasiteaden tissues. Further downstream, TCTs process surface bound HK, liberatinglysyl-BK (LBK), which then propagates inflammatory edemavia signaling of endothelial G-protein-coupled bradykinin B2 receptors (BK2R). Dm28 TCTs take advantage of the transientavailability of infection-promoting peptides (e.g.,bradykinin and endothelins)in inflamed tissues to in vadecardiovascular cells viainter dependent signaling of BKRs and endothelin receptors (ETRs). Here in we present a space-filling model where by ceramide enrichedendocytic vesicles generated by the sphingomyelinase pathway might in corporate BK2R and ETRs, which then trigger Ca2+-driven responses that optimize the housekeeping mechanism of plasma membrane repair from cell wounding. The hypothesis predicts that the NF-κB-inducibleBKR(BK1R)may integrate the multimolecular signaling platforms forged by ceramiderafts, asthechronicmyocarditis progresses. Exploitedas gateways for parasiteinvasion, BK2R, BK1R,ETAR,ETBR, and other Gprotein-couple dreceptor partners may enable persistent myocardial parasitism in the edematous tissues at expense of adverse cardiac remodeling. [ABSTRACT FROM AUTHOR]

Chronic chagasic myocarditis (CCM) depends on Trypanosoma cruzi persistence in the myocardium. Studies of the proteolytic mechanisms governing host/parasite balance in peripheral sites of T. cruzi infection revealed that tissue culture trypomastigotes (TCTs) elicit inflammatory edema and stimulate protective type-1 effector T cells through the activation of the Kallikrein-Kinin System (KKS). Molecular studies linked the proinflammatory phenotype of Dm28c TCTs to the synergistic activities of tGPI, a lipid anchor that functions as a TLR2 ligand, and cruzipain, a kinin-releasing cysteine protease. Analysis of the dynamics of inflammation revealed that TCTs activate innate sentinel cells via TLR2, releasing CXC chemokines, which in turn evoke neutrophil/CXCR2-dependent extravasation of plasma proteins, including high molecular weight kininogen (HK), in parasite-laden tissues. Further downstream, TCTs process surface bound HK, liberating lysyl-BK (LBK), which then propagates inflammatory edema via signaling of endothelial Gprotein- coupled bradykinin B2 receptors (BK2R). Dm28 TCTs take advantage of the transient availability of infection-promoting peptides (e.g., bradykinin and endothelins) in inflamed tissues to invade cardiovascular cells via interdependent signaling of BKRs and endothelin receptors (ETRs). Herein we present a space-filling model whereby ceramideenriched endocytic vesicles generated by the shingomyelinase pathway might incorporate BK2R and ETRs, which then trigger Ca2+-driven responses that optimize the housekeeping mechanism of plasma membrane repair from cell wounding. The hypothesis predicts that the NFκB-inducible BKR (BK1R) may integrate the multimolecular signaling platforms forged by ceramide rafts, as the chronic myocarditis progresses. Exploited as gateways for parasite invasion, BK2R, BK1R, ETAR, ETBR and other GPCR partners may enable persistent myocardial parasitism in the edematous tissues at expense of adverse cardiac remodelling. [ABSTRACT FROM AUTHOR]

Chronic chagasic myocarditis (CCM) depends on Trypanosoma cruzi persistence in the myocardium. Studies of the proteolytic mechanisms governing host/parasite balance in peripheral sites of T. cruzi infection revealed that tissue culture trypomastigotes (TCTs) elicit inflammatory edema and stimulate protective type-1 effector T cells through the activation of the kallikrein-kinin system. Molecular studies linked the proinflammatory phenotype of Dm28c TCTs to the synergistic activities of tGPI, a lipid anchor that functions as a Toll-like receptor 2 (TLR2) ligand, and cruzipain, a kinin-releasing cysteine protease. Analysis of the dynamics of inflammation revealed that TCTs activate innate sentinel cells via TLR2, releasing CXC chemokines, which in turn evoke neutrophil/CXCR2-dependent extravasation of plasma proteins, including high molecular weight kininogen (HK), in parasite-laden tissues. Further downstream, TCTs process surface bound HK, liberating lysyl-BK (LBK), which then propagates inflammatory edema via signaling of endothelial G-protein-coupled bradykinin B(2) receptors (BK(2)R). Dm28 TCTs take advantage of the transient availability of infection-promoting peptides (e.g., bradykinin and endothelins) in inflamed tissues to invade cardiovascular cells via interdependent signaling of BKRs and endothelin receptors (ETRs). Herein we present a space-filling model whereby ceramide-enriched endocytic vesicles generated by the sphingomyelinase pathway might incorporate BK(2)R and ETRs, which then trigger Ca(2+)-driven responses that optimize the housekeeping mechanism of plasma membrane repair from cell wounding. The hypothesis predicts that the NF-κB-inducible BKR (BK(1)R) may integrate the multimolecular signaling platforms forged by ceramide rafts, as the chronic myocarditis progresses. Exploited as gateways for parasite invasion, BK(2)R, BK(1)R, ET(A)R, ET(B)R, and other G protein-coupled receptor partners may enable persistent myocardial parasitism in the edematous tissues at expense of adverse cardiac remodeling.

Objective: Ischemic preconditioning and some drugs can protect tissues from injury by preserving microcirculation. This study evaluated vascular permeability in a hamster cheek pouch preparation using either short ischemic periods or bradykinin as preconditioning stimuli followed by 30 min of ischemia/reperfusion., Method: Sixty-six male hamsters were divided into 11 groups: five combinations of different ischemic frequencies and durations (one, three or five shorts periods of ischemia, separated by one or five minutes) with 10 min intervals between the ischemic periods, followed by 30 min ischemia/reperfusion; three or five 1 min ischemic periods with 10 min intervals between them followed by the topical application of histamine (2 µM); bradykinin (400 nM) followed by 30 min of ischemia/reperfusion; and three control groups (30 min of ischemia/reperfusion or histamine or bradykinin by themselves). Macromolecular permeability was assessed by injection of fluorescein-labeled dextran (FITC-dextran, MW= 150 kDa; 250 mg/Kg body weight), and the number of leaks/cm2 was counted using an intravital microscope and fluorescent light in the cheek pouch., Results: Plasma leakage (number of leaks/cm²) was significantly reduced by preconditioning with three and five 1 min ischemic periods, one and three 5 min ischemic periods and by bradykinin. Histamine-induced macromolecular permeability was also reduced after three periods of 5 min of ischemia., Conclusion: Short ischemic periods and bradykinin can function as preconditioning stimuli of the ischemia/reperfusion response in the hamster cheek pouch microcirculation. Short ischemic periods also reduced histamineinduced macromolecular permeability.

Porphyromonas gingivalis, a Gram-negative bacterium that causes periodontitis, activates the kinin system via the cysteine protease R-gingipain. Using a model of buccal infection based on P. gingivalis inoculation in the anterior mandibular vestibule, we studied whether kinins released by gingipain may link mucosal inflammation to T cell-dependent immunity through the activation of bradykinin B(2) receptors (B(2)R). Our data show that P. gingivalis W83 (wild type), but not gingipain-deficient mutant or wild-type bacteria pretreated with gingipain inhibitors, elicited buccal edema and gingivitis in BALB/c or C57BL/6 mice. Studies in TLR2(-/-), B(2)R(-/-), and neutrophil-depleted C57BL/6 mice revealed that P. gingivalis induced edema through the sequential activation of TLR2/neutrophils, with the initial plasma leakage being amplified by gingipain-dependent release of vasoactive kinins from plasma-borne kininogens. We then used fimbriae (Fim) Ag as a readout to verify whether activation of the TLR2-->PMN-->B(2)R axis (where PMN is polymorphonuclear neutrophil) at early stages of mucosal infection had impact on adaptive immunity. Analyzes of T cell recall responses indicated that gingipain drives B(2)R-dependent generation of IFN-gamma-producing Fim T cells in submandibular draining lymph nodes of BALB/c and C57BL/6 mice, whereas IL-17-producing Fim T cells were generated only in BALB/c mice. In summary, our studies suggest that two virulence factors, LPS (an atypical TLR2 ligand) and gingipain, forge a trans-cellular cross-talk between TLR2 and B(2)R, thus forming an innate axis that guides the development of Fim-specific T cells in mice challenged intrabuccally by P. gingivalis. Ongoing research may clarify whether kinin-driven modulation of T cell responses may also influence the severity of chronic periodontitis.