Lipoxin A(4) attenuates zymosan-induced arthritis by modulating endothelin-1 and its effects

BACKGROUND AND PURPOSE

Lipoxin A(4) (LXA(4)) is a lipid mediator involved in the resolution of inflammation. Increased levels of LXA(4) in synovial fluid and enhanced expression of the formyl peptide receptor 2/lipoxin A(4) receptor (FPR2/ALX) in the synovial tissues of rheumatoid arthritis patients have been reported. Endothelins (ETs) play a pivotal pro-inflammatory role in acute articular inflammatory responses. Here, we evaluated the anti-inflammatory role of LXA(4), during the acute phase of zymosan-induced arthritis, focusing on the modulation of ET-1 expression and its effects.

EXPERIMENTAL APPROACH

The anti-inflammatory effects of LXA(4), BML-111 (agonist of FPR2/ALX receptors) and acetylsalicylic acid (ASA) pre- and post-treatments were investigated in a murine model of zymosan-induced arthritis. Articular inflammation was assessed by examining knee joint oedema; neutrophil accumulation in synovial cavities; and levels of prepro-ET-1 mRNA, leukotriene (LT)B(4), tumour necrosis factor (TNF)-α and the chemokine KC/CXCL1, after stimulation. The direct effect of LXA(4) on ET-1-induced neutrophil activation and chemotaxis was evaluated by shape change and Boyden chamber assays respectively.

KEY RESULTS

LXA(4), BML-111 and ASA administered as pre- or post-treatment inhibited oedema and neutrophil influx induced by zymosan stimulation. Zymosan-induced preproET-1 mRNA, KC/CXCL1, LTB(4) and TNF-α levels were also decreased after LXA(4) pretreatment. In vitro, ET-1-induced neutrophil chemotaxis was inhibited by LXA(4) pretreatment. LXA(4) treatment also inhibited ET-1-induced oedema formation and neutrophil influx into mouse knee joints.

CONCLUSION AND IMPLICATION

LXA(4) exerted anti-inflammatory effects on articular inflammation through a mechanism that involved the inhibition of ET-1 expression and its effects.

Antiinflammatory effects of natural tetranortriterpenoids isolated from Carapa guianensis Aublet on zymosan-induced arthritis in mice

OBJECTIVE

We investigated the antiinflammatory properties of a derived fraction of tetranortriterpenoids (TNTP) obtained from the seeds of Carapa guianensis Aublet.

MATERIAL AND METHODS

Zymosan-induced arthritis and pleurisy in Swiss and C57/Bl6 mice (n = 10 per group). Western blot analysis was performed to analyze nuclear factor-kappaB (NFkappaB) translocation in mice peritoneal macrophages stimulated in vitro with zymosan (500 microg/ml). ELISA was performed to evaluate cytokine levels in knee joints. Values of p </= 0.05 were regarded as significant.

RESULTS

Zymosan intra-articular (i. a.) injection (500microg/ cavity) induced a significant increase in knee joint diameter within 6 h, peaked within 24 h and remained above control values for 20 days. Orally-given (p. o.) TNTP (100-200 mg/ kg) inhibited zymosan-induced increase in knee joint diameter and protein extravazation into synovial cavity within 6 h. TNTP (100-200 mg/kg, p. o.) also inhibited total leukocyte influx into the synovial space and tissue, as well as into the mice pleural cavity, due to neutrophil impairment 6 h after zymosan stimulation. The increase in TNF-alpha, IL-1beta and CXCL8/IL-8 levels that were detected in knee synovial extracts obtained from zymosan-stimulated mice was also inhibited by TNTP (100 mg/kg, p. o.). Moreover, the incubation of mice peritoneal macrophages with TNTP (100 mug/ml) inhibited zymosan (500 microg/ml)-induced NFkappaB translocation into the nucleus 6 h after stimulation.

CONCLUSION

Taken together, these results indicate that TNTP present an important antiinflammatory effect, inhibiting zymosan-induced arthritis in mice via the impairment of TNF-alpha, IL-1beta and CXCL8/IL-8 generation, as well as NFkappaB signaling pathway.

Anti-allergic effects of natural tetranortriterpenoids isolated from Carapa guianensis Aublet on allergen-induced vascular permeability and hyperalgesia

OBJECTIVE

We investigated the anti-allergic and analgesic properties of an oil and a derived fraction of tetranortriterpenoids (TNTP) obtained from the seeds of Carapa guianensis Aublet.

MATERIALS AND METHODS

Pleurisy, paw and ear edema were induced in Swiss and C57/Bl10 mice mice, whereas thermal hyperalgesia was assessed in Wistar rats (n = 6-10 per group). Values of p < 0.05 were regarded as significant.

RESULTS

C. guianensis oil (100 to 400 mg/kg, p.o.) and TNTP (12.5 to 100 mg/kg, p.o.) inhibited pleural exudation, paw and ear edema induced by ovalbumin (OVA) in sensitized mice. TNTP (12.5 to 100 mg/kg, p.o.) also inhibited paw edema induced by histamine, PAF and bradykinin. TNTP (100 mg/kg, p.o.) inhibited prostaglandin E(2) generation in the pleural cavity in response to antigenic challenge. Moreover, C. guianensis oil (100 to 400 mg/kg) and TNTP (12.5 to 100 mg/kg) decreased OVA- and histamine-induced hyperalgesia.

CONCLUSION

Taken together, these findings demonstrate the anti-edematogenic and analgesic effects of C. guianensis oil, and points out TNTP as the responsible bioactive compounds.

Role of Monocyte Chemotactic Protein-1/CC Chemokine Ligand 2 on γδ T Lymphocyte Trafficking during Inflammation Induced by Lipopolysaccharide orMycobacterium bovisBacille Calmette-Guérin

Gammadelta T lymphocytes are involved in a great variety of inflammatory and infectious responses. However, the mechanisms by which gammadelta T lymphocytes migrate to inflamed sites are poorly understood. In this study we investigate the role of monocyte chemotactic protein (MCP)-1 in regulating gammadelta T cell migration after LPS or Mycobacterium bovis bacille Calmette-Guérin (BCG) challenge. LPS-induced gammadelta T cell influx was significantly inhibited by either pretreatment with dexamethasone or vaccinia virus Lister 35-kDa chemokine binding protein, vCKBP, a CC chemokine neutralizing protein, suggesting a role for CC chemokines in this phenomenon. LPS stimulation increased the expression of MCP-1 mRNA and protein at the inflammation site within 6 h. It is noteworthy that LPS was unable to increase MCP-1 production or gammadelta T cell recruitment in C3H/HeJ, indicative of the involvement of Toll-like receptor 4. Gammadelta T cells express MCP-1 receptor CCR2. Pretreatment with anti-MCP-1 mAb drastically inhibited LPS-induced in vivo gammadelta T cell mobilization. Indeed, MCP-1 knockout mice were unable to recruit gammadelta T cells to the pleural cavity after LPS stimulation, effect that could be restored by coadministration of MCP-1. In addition, BCG-induced gammadelta lymphocyte accumulation was significantly reduced in MCP-1 knockout mice when compared with wild-type mice. In conclusion, our results indicate that LPS-induced gammadelta T lymphocyte migration is dependent on Toll-like receptor 4 and sensitive to both dexamethasone and CC chemokine-binding protein inhibition. Moreover, by using MCP-1 neutralizing Abs and genetically deficient mice we show that LPS- and BCG-induced gammadelta T lymphocyte influx to the pleural cavity of mice is mainly orchestrated by the CC chemokine MCP-1.

Natural heat shock protein 90 inhibitors in cancer and inflammation

Heat shock protein (HSP)90 is the most abundant HSPs, which are chaperone molecules whose major roles are cell protection and maintenance by means of aiding the folding, the stabilization and the remodeling of a wide range of proteins. A few hundreds of proteins depend on HSP90 chaperone activity, including kinases and transcriptional factors that play essential roles in cancer and inflammation, so that HSP90-targeted therapies have been considered as a potential strategy for the treatment of cancer and inflammatory-associated diseases. HSP90 inhibition by natural, semi-synthetic and synthetic compounds have yield promising results in pre-clinical studies and clinical trials for different types of cancers and inflammation. Natural products are a huge source of biologically active compounds widely used in drug development due to the great diversity of their metabolites which are capable to modulate several protein functions. HSP90 inhibitors have been isolated from bacteria, fungi and vegetal species. These natural compounds have a noteworthy ability to modulate HSP90 activity as well as serve as scaffolds for the development of novel synthetic or semi-synthetic inhibitors. Over a hundred clinical trials have evaluated the effect of HSP90 inhibitors as adjuvant treatment against different types of tumors and, currently, new studies are being developed to gain sight on novel promising and more effective approaches for cancer treatment. In this review, we present the naturally occurring HSP90 inhibitors and analogues, discussing their anti-cancer and anti-inflammatory effects.

Endothelins modulate inflammatory reaction in zymosan-induced arthritis: participation of LTB4, TNF-alpha, and CXCL-1

Endothelins (ETs) are involved in inflammatory events, including pain, fever, edema, and cell migration. ET-1 levels are increased in plasma and synovial membrane of rheumatoid arthritis (RA) patients, but the evidence that ETs participate in RA physiopathology is limited. The present study investigated the involvement of ETs in neutrophil accumulation and edema formation in the murine model of zymosan-induced arthritis. Intra-articular (i.a.) administration of selective ET(A) or ET(B) receptor antagonists (BQ-123 and BQ-788, respectively; 15 pmol/cavity) prior to i.a. zymosan injection (500 microg/cavity) markedly reduced knee-joint edema formation and neutrophil influx to the synovial cavity 6 h and 24 h after stimulation. Histological analysis showed that ET(A) or ET(B) receptor blockade suppressed zymosan-induced neutrophil accumulation in articular tissue at 6 h. Likewise, dual blockade of ET(A)/ET(B) with bosentan (10 mg/kg, i.v.) also reduced edema formation and neutrophil counts 6 h after zymosan stimulation. Pretreatment with BQ-123 or BQ-788 (i.a.; 15 pmol/cavity) also decreased zymosan-induced TNF-alpha production within 6 h, keratinocyte-derived chemokine/CXCL1 production within 24 h, and leukotriene B(4) at both time-points. Consistent with the demonstration that ET receptor antagonists inhibit zymosan-induced inflammation, i.a. injection of ET-1 (1-30 pmol/cavity) or sarafotoxin S6c (0.1-30 pmol/cavity) also triggered edema formation and neutrophil accumulation within 6 h. Moreover, knee-joint synovial tissue expressed ET(A) and ET(B) receptors. These findings suggest that endogenous ETs contribute to knee-joint inflammation, acting through ET(A) and ET(B) receptors and modulating edema formation, neutrophil recruitment, and production of inflammatory mediators.

LPS induces eosinophil migration via CCR3 signaling through a mechanism independent of RANTES and Eotaxin

Mounting evidence suggests that lipopolysaccharide (LPS) modulates bronchoconstriction and eosinophil function in asthma. We have investigated the role of different chemokines in the eosinophil influx to the pleural cavity after LPS stimulation. Expression of mRNA for eotaxin, regulated on activation, normal T cells expressed and secreted (RANTES), macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, MIP-2, and monocyte chemotactic protein (MCP)-1 was increased in cells recovered from the mouse pleural cavity 6 h after LPS administration. Eotaxin and RANTES, but not MIP-1alpha, protein levels were also increased in cell-free pleural washes recovered 6 h after LPS stimulation (LPW). Antimurine eotaxin and antimurine RANTES antibodies (Abs) failed to inhibit LPS-induced eosinophil influx into mouse pleural cavity in vivo. Pertussis toxin inhibited LPW-induced eosinophil shape change in vitro, suggesting the involvement of G protein-coupled receptors in LPW signaling. Blockade of CCR3 receptors diminished eosinophil shape change induced by LPW fractions in vitro and LPS-induced eosinophil accumulation in vivo. To investigate further contribution of CC chemokines, we administered a 35-kD CC chemokine neutralizing protein (vCKBP) in vivo. vCKBP inhibited the eosinophil accumulation induced by eotaxin and ovalbumin, but did not block that induced by LPS or LPW. Our data suggest that LPS-induced eosinophil accumulation depends on G protein-coupled CCR3 receptor activation, through a mechanism independent of eotaxin, RANTES, or other vCKBP-inhibitable CC chemokines.

Involvement of CC chemokines in gammadelta T lymphocyte trafficking during allergic inflammation: the role of CCL2/CCR2 pathway

In the present study, we show that the intra-thoracic injection of ovalbumin (OVA, 12.5 microg per cavity) into C57BL/10 mice induced a significant increase in gammadelta T lymphocyte numbers in the pleural cavity, blood and thoracic lymph node of challenged mice. Such increase was significant within 12 h, peaked within 48 h and returned to basal counts within 120 h. Levels of CC chemokine ligand (CCL)-2/monocyte chemotactic protein-1, CCL5/regulated upon activation, normal T cell expressed and secreted, CCL3/macrophage inflammatory protein-1 alpha and CCL25/thymus-expressed chemokine were above control values in pleural washes recovered 24 h after OVA challenge (OPW) and were likely produced by pleural macrophages and mesothelial cells. Antigenic challenge also induced an up-regulation in CC chemokine receptor (CCR)-2, CCR5 and CCR9 on gammadelta T cells from pleural cavities, blood and lymph nodes, suggesting that cells found in mice pleural cavity migrate from secondary lymphoid organs into the inflammatory site via blood stream. The in vitro neutralization of CCL2 (but not of CCL3, CCL5 or CCL25) abrogated OPW-induced gammadelta T lymphocyte transmigration. Confirming such results, the in vivo administration of alpha-CCL2 mAb inhibited gammadelta T lymphocyte accumulation in the pleural cavity of challenged mice, whereas the blockade of CCL3, CCL5 or CCL25 showed no effect on gammadelta T cell mobilization. In addition, OVA challenge failed to induce gammadelta T lymphocyte accumulation in the pleural cavity of C57BL/6 CCR2 knockout mice, which also showed decreased numbers of these cells in blood and lymph nodes when compared with wild-type mice. Overall, such results demonstrate that CCR2/CCL2 pathway is crucial for gammadelta T lymphocyte mobilization during the allergic response.

Inhibition of allergen-induced eosinophil recruitment by natural tetranortriterpenoids is mediated by the suppression of IL-5, CCL11/eotaxin and NFkappaB activation

The present study reports the anti-allergic activity of a group of six different tetranortriterpenoids (TNTP) isolated from the seeds of Carapa guianensis Aublet: 6a-acetoxygedunin, 7-deacetoxy-7-oxogedunin, andirobin, methyl angolensate, 6a-acetoxyepoxyazadiradione and gedunin. Oral pretreatment with TNTP significantly inhibited total leukocyte and eosinophil accumulation in C57BL/10 mice pleural cavities 24 h after the intrathoracic (i.t.) injection of ovalbumin (OVA), but had no effect on CD4, CD8 or gammadelta T lymphocyte accumulation. Pleural washes recovered from 6 h OVA-stimulated mice (OPW) pretreated with TNTP failed to induce shape change in eosinophil in vitro, indicating the inhibition of eosinophilotactic chemokines by TNTP. In accordance with such results, ELISA assays showed decreased levels of CCL11/eotaxin and IL-5 in OPW recovered from TNTP pretreated mice within 6 h. TNTP oral pretreatment inhibited nuclear factor-kappaB (NFkappaB) translocation into the nucleus in pleural leukocytes recovered from previously sensitized mice after antigenic challenge. In addition, the incubation of splenocytes recovered from previously sensitized mice with TNTP also inhibited NFkappaB activation after OVA stimulation. Taken together, these results indicate that the inhibition of allergic eosinophilia by TNTP is correlated with the inhibition of CCL11/eotaxin and IL-5 generation through NFkappaB signaling pathway impairment in mice.

Leukotriene B4 mediates gammadelta T lymphocyte migration in response to diverse stimuli

Herein, we investigated the involvement of the 5-LO-derived lipid mediator LTB(4) in gammadelta T cell migration. When injected into the i.pl. space of C57BL/6 mice, LTB(4) triggered gammadelta T lymphocyte mobilization in vivo, a phenomenon also observed in in vitro chemotaxis assays. The i.pl. injection of Escherichia coli endotoxin (LPS) triggered increased levels of LTB(4) in pleural cavities. The in vivo inhibition of LTB(4) biosynthesis by the 5-LO inhibitor zileuton or the FLAP inhibitor MK886 attenuated LPS-induced gammadelta T cell accumulation into pleural cavities. Accordingly, 5-LO KO mice failed to recruit gammadelta T cells into the inflammatory site after i.pl. LPS. Antagonists of the high-affinity LTB(4) receptor BLT1, CP105,696, and LY292476 also attenuated LPS-induced gammadelta T cell accumulation in pleural cavities as well as in vitro chemotaxis toward pleural washes obtained from LPS-simulated mice. LTB(4)/BLT1 also accounted for gammadelta T cell migration induced by i.pl. administration of Mycobacterium bovis BCG or antigen in sensitized mice. BLT1 was expressed on naïve, resident as well as LPS-recruited gammadelta T cells. Isolated gammadelta T cells were found to undergo F-actin cytoskeleton reorganization when incubated with LTB(4) in vitro, confirming that gammadelta T lymphocytes can respond directly to LTB(4). In addition to its direct effect on gammadelta T cells, LTB(4) triggered their accumulation indirectly, via modulation of CCL2 production in mouse pleural cavities. These data show that gammadelta T cell migration into the pleural cavity of mice during diverse inflammatory responses is dependent on LTB(4)/BLT1.

Role of Chemokine Receptor CCR4 and Regulatory T Cells in Wound Healing of Diabetic Mice

Wound healing is a well-coordinated process that involves inflammatory mediators and cellular responses; however, if any disturbances are present during this process, tissue repair is impaired. Chronic wounds are one of the serious long-term complications associated with diabetes mellitus. The chemokine receptor CCR4 and its respective ligands, CCL17 and CCL22, are involved in regulatory T cell recruitment and activation in inflamed skin; however, the role of regulatory T cells in wounds is still not clear. Our aim was to investigate the role of CCR4 and regulatory T cells in cutaneous wound healing in diabetic mice. Alloxan-induced diabetic wild- type mice (diabetic) developed wounds that were difficult to heal, differently from CCR4^-/- diabetic mice (CCR4^-/- diabetic), and also from anti-CCL17/22 or anti-CD25-injected diabetic mice that presented with accelerated wound healing and fewer regulatory T cells in the wound bed. Consequently, CCR4^-/- diabetic mice also presented with alteration on T cells population in the wound and draining lymph nodes; on day 14, these mice also displayed an increase of collagen fiber deposition. Still, cytokine levels were decreased in the wounds of CCR4^-/- diabetic mice on day 2. Our data suggest that the receptor CCR4 and regulatory T cells negatively affect wound healing in diabetic mice.

CCL25 induces α₄β₇ integrin-dependent migration of IL-17⁺ γδ T lymphocytes during an allergic reaction

Herein, we provide evidence that during allergic inflammation, CCL25 induces the selective migration of IL-17(+) γδ T cells mediated by α(4) β(7) integrin. Intrapleural injection of CCL25 into ovalbumin (OVA)-immunized C57BL/6 mice triggered the accumulation of γδ T lymphocytes expressing CCR9 (CCL25 receptor) and α(4) β(7) integrin in the pleura, but failed to attract αβ T lymphocytes. CCL25 attracted CCR6(+) γδ T cells producing IL-17 (but not IFN-γ or IL-4). OVA challenge triggered increased production of CCL25 followed by the accumulation of CCR9(+) , α(4) β(7) (+) , and CCR6(+) /IL-17(+) γδ T cells into the pleural cavities of OVA-immunized mice, which was inhibited by the in vivo neutralization of CCL25. The in vivo blockade of α(4) β(7) integrin also inhibited the migration of IL-17(+) γδ T lymphocytes (but not of αβ T lymphocytes) into mouse pleura after OVA challenge, suggesting that the CCL25/α(4) β(7) integrin pathway is selective for γδ T cells. In addition, α(4) β(7) integrin blockade impaired the in vitro transmigration of γδ T cells across endothelium (which expresses α(4) β(7) ligands VCAM-1 and MadCAM-1), which was induced by CCL25 and by cell-free pleural washes recovered from OVA-challenged mice. Our results reveal that during an allergic reaction, CCL25 drives IL-17(+) γδ T-cell mobilization to inflamed tissue via α(4) β(7) integrin and modulates IL-17 levels.

Murine IL-17+ Vγ4 T lymphocytes accumulate in the lungs and play a protective role during severe sepsis

Background

Lung inflammation is a major consequence of the systemic inflammatory response caused by severe sepsis. Increased migration of γδ T lymphocytes into the lungs has been previously demonstrated during experimental sepsis; however, the involvement of the γδ T cell subtype Vγ4 has not been previously described.

Methods

Severe sepsis was induced by cecal ligation and puncture (CLP; 9 punctures, 21G needle) in male C57BL/6 mice. γδ and Vγ4 T lymphocyte depletion was performed by 3A10 and UC3-10A6 mAb i.p. administration, respectively. Lung infiltrating T lymphocytes, IL-17 production and mortality rate were evaluated.

Results

Severe sepsis induced by CLP in C57BL/6 mice led to an intense lung inflammatory response, marked by the accumulation of γδ T lymphocytes (comprising the Vγ4 subtype). γδ T lymphocytes present in the lungs of CLP mice were likely to be originated from peripheral lymphoid organs and migrated towards CCL2, CCL3 and CCL5, which were highly produced in response to CLP-induced sepsis. Increased expression of CD25 by Vγ4 T lymphocytes was observed in spleen earlier than that by αβ T cells, suggesting the early activation of Vγ4 T cells. The Vγ4 T lymphocyte subset predominated among the IL-17⁺ cell populations present in the lungs of CLP mice (unlike Vγ1 and αβ T lymphocytes) and was strongly biased toward IL-17 rather than toward IFN-γ production. Accordingly, the in vivo administration of anti-Vγ4 mAb abrogated CLP-induced IL-17 production in mouse lungs. Furthermore, anti-Vγ4 mAb treatment accelerated mortality rate in severe septic mice, demonstrating that Vγ4 T lymphocyte play a beneficial role in host defense.

Conclusions

Overall, our findings provide evidence that early-activated Vγ4 T lymphocytes are the main responsible cells for IL-17 production in inflamed lungs during the course of sepsis and delay mortality of septic mice.

Electronic supplementary material

The online version of this article (doi:10.1186/s12865-015-0098-8) contains supplementary material, which is available to authorized users.

IL-5 accounts for the mouse pleural eosinophil accumulation triggered by antigen but not by LPS

The involvement of interleukin-5 (IL-5) in the pleural eosinophilia induced by LPS or allergen was investigated. The number of pleural eosinophils in actively sensitized mice increased 24 h after the intrathoracic (i.t.) injection of ovalbumin (12 mg/cavity), peaked within 72 h, and persisted significantly increased for at least 120 h. Despite being less intense, the i.t. injection of LPS (250 ng/cavity) also increased the number of pleural eosinophils at 24 h, returning to basal levels within 72 h. Intraperitoneal pretreatment with monoclonal antibody to IL-5 (TRFK-4 and TRFK-5, 500 mg/kg) suppressed the eosinophil accumulation induced by IL-5 (200 units/cavity) or ovalbumin, but had no effect on the LPS-induced eosinophilia. Transfer of the cell-free pleural washing from LPS-treated donor mice to naive recipient animals led to a selective increase in the eosinophil counts. The co-incubation of the pleural washing from LPS-treated animals with monoclonal antibody to IL-5 failed to modify the phenomenon. The results indicate that IL-5 plays an important role in the antigen-induced accumulation of eosinophils in vivo, but not in the eosinophilia triggered by LPS.

γδ T Lymphocytes Coordinate Eosinophil Influx during Allergic Responses

Tissue eosinophil infiltration, which is a hallmark of allergic and helminthic diseases, is mainly coordinated by T lymphocytes, via the production of eosinophilotactic chemokines. Among T lymphocyte subsets, lymphocytes expressing γδ T cell receptor have been determined as a key factor for eosinophil accumulation via direct and indirect mechanisms. This knowledge is strongly supported by the fact that, in different experimental models of eosinophilic airway inflammation and helminth-induced Th2 lung inflammation, an evident tissue accumulation of γδ T lymphocytes is observed. In addition, the depletion of γδ T lymphocytes is correlated with the impairment of eosinophil accumulation in inflamed tissue. γδ T lymphocytes are non-conventional T lymphocytes, which comprise a minor T lymphocyte subset, mainly distributed in the tissue, and present crucial roles in innate and acquired immune responses. γδ T lymphocytes recognize several danger- and pathogen-associated molecular pattern molecules and stress antigens in a MHC-independent fashion and can provide rapid tissue-specific responses, via the production of a wide range of chemical mediators capable to modulate other cell populations. These mediators include chemoattractant cytokines and chemokines that attract eosinophils into the tissue by either direct recognition (such as IL-5, CCL11/eotaxin), or indirect mechanisms via the modulation of αβ T lymphocytes and macrophages (through the production of interferon-γ, IL-4, and CCL2/Monocyte chemoattractant protein-1, MCP-1, for example). The present review presents an overview of how γδ T lymphocytes coordinate eosinophil accumulation in allergy, by focusing on their role in airway inflammation and by discussing the involvement of cytokines and chemokines in this phenomenon.

Lipoxin A4 attenuates endothelial dysfunction during experimental cerebral malaria

A breakdown of the brain-blood barrier (BBB) due to endothelial dysfunction is a primary feature of cerebral malaria (CM). Lipoxins (LX) are specialized pro-resolving mediators that attenuate endothelial dysfunction in different vascular beds. It has already been shown that LXA4 prolonged Plasmodium berghei-infected mice survival by a mechanism that depends on inhibiting IL-12 production and CD8(+)IFN-γ(+) T cells in brain tissue; however, the effects of this treatment on endothelial dysfunction induced during experimental cerebral malaria (ECM) remains to be elucidated. Herein, we investigate the role of LXA4 on endothelial dysfunction during ECM. The treatment of P. berghei-infected mice with LXA4 prevented BBB breakdown and ameliorated behavioral symptoms but did not modulate TNF-α production. In addition, microcirculation analysis showed that treatment with LXA4 significantly increased functional capillary density in brains of P. berghei-infected C57BL/6 mice. Furthermore, histological analyses of brain sections demonstrated that exogenous LXA4 reduced capillary congestion that was accompanied by reduced ICAM-1 expression in the brain tissue. In agreement, LXA4 treatment of endothelial cells stimulated by Plasmodium berghei (Pb)- or Plasmodium falciparum (Pf)-parasitized red blood cells (RBCs) inhibited ICAM-1 expression. Additionally, LXA4 treatment restored the expression of HO-1 that is reduced during ECM. As well, LXA4 treatment inhibits PbRBC and PfRBC adhesion to endothelial cells that was reversed by the use of an HO-1 inhibitor (ZnPPIX). Our results demonstrate for the first time that LXA4 ameliorates endothelial dysfunction during ECM by modulating ICAM-1 and HO-1 expression in brain tissue.

Anti-inflammatory and anti-ulcerogenic properties of Stachytarpheta cayennensis (L.C. Rich) Vahl

In the present work, the anti-inflammatory and gastroprotective properties of ethanolic extracts of Stachytarpheta cayennesis (L.C. Rich) Vahl (Verbenaceae) were assessed. Chromatographic analysis of the crude ethanolic extract, SC01, revealed high concentrations of the iridoid ipolamiide, whereas the SC02, the second ethanolic extract, presented the arylpropanoid verbacoside as a major constituent. The oral administration of SC01 (100 mg/kg) into Swiss mice failed to inhibit paw oedema and pleural exudation induced by carrageenan and zymosan, whereas SC02 (100 mg/kg, p.o.) inhibited oedema and protein extravasation in all instances. Both extracts inhibited total leukocyte accumulation into the pleural cavity 4 and 24h after the intrathoracic (i.t.) injection of carrageenan, due to the inhibition of neutrophil and mononuclear cell influx, whereas only SC02 was able to inhibit leukocyte mobilization induced by zymosan (100 microg/cavity, i.t.). SC02 inhibited LPS (250 ng/cavity)-induced total leukocyte, neutrophil and eosinophil accumulation in the pleural cavity, whereas SC01 selectively inhibited neutrophil influx. In addition, our data indicates that the extract SC02 presents an important anti-ulcerogenic activity, since it inhibited diclofenac-induced (100 mg/kg, p.o.) gastric ulcera. Overall, these data provide evidence for the anti-inflammatory and gastroprotective properties of Stachytarpheta cayennensis, supporting its use in folk medicine for such purposes.