Maria Ignez Gaspar-Elsas

Macrophage migration inhibitory factor is critical to interleukin-5-driven eosinophilopoiesis and tissue eosinophilia triggered by Schistosoma mansoni infection

Macrophage migration inhibitory factor (MIF) participates in the pathogenesis of inflammatory diseases, including asthma, in which it enhances airway hypersensitivity and tissue eosinophilia. Herein, we investigated the role of MIF in eosinophilopoiesis and tissue eosinophilia using Schistosoma mansoni infection. MIF‐deficient (Mif−/−) mice had similar numbers of adult worms, eggs, and granulomas compared to wildtype mice, but the size of granulomas was strikingly reduced due to smaller numbers of eosinophils. MIF did not affect the acquired response to infection, as Mif−/− mice produced normal amounts of Th2 cytokines and IgE. Nevertheless, recombinant MIF (rMIF) behaved as a chemoattractant for eosinophils, what could partially explain the reduced eosinophilia in infected Mif−/− mice. Moreover, the percentage of eosinophils was reduced in bone marrows of Mif−/− mice chronically infected with S. mansoni compared to wild type. Mif−/− had impaired eosinophilopoiesis in response to interleukin (IL)‐5 and addition of rMIF to bone marrow cultures from IL‐5 transgenic mice enhanced the generation of eosinophils. In the absence of MIF, eosinophil precursors were unable to survive the IL‐5‐supplemented cell culture, and were ingested by macrophages. Treatment with pancaspase inhibitor z‐VAD or rMIF promoted the survival of eosinophil progenitors. Together, these results indicate that MIF participates in IL‐5‐driven maturation of eosinophils and in tissue eosinophilia associated with S. mansoni infection.—Magalhaes, E. S., Paiva, C. N., Souza, H. S. P., Pyrrho, A. S., Mourao‐Sa, D., Figueiredo, R. T., Vieira‐de‐Abreu, A., Dutra, H. S., Silveira, M. S., Gaspar‐Elsas, M. I. C., Xavier‐Elsas, P., Bozza, P. T., Bozza, M. T. Macrophage migration inhibitory factor is critical to interleukin‐5‐driven eosinophilopoiesis and tissue eosinophilia triggered by Schistosoma mansoni infection. FASEB J. 23, 1262–1271 (2009)

Inducible Nitric Oxide Synthase/CD95L-dependent Suppression of Pulmonary and Bone Marrow Eosinophilia by Diethylcarbamazine

RATIONALE The mechanism of action of diethylcarbamazine (DEC), an antifilarial drug effective against tropical pulmonary eosinophilia, remains controversial. DEC effects on microfilariae depend on inducible NO synthase (iNOS). In eosinophilic pulmonary inflammation, its therapeutic mechanism has not been established. We previously described the rapid up-regulation of bone marrow eosinophilopoiesis in ovalbumin (OVA)-sensitized mice by airway allergen challenge, and further evidenced the down-regulation of eosinophilopoiesis by iNOS- and CD95L-dependent mechanisms. OBJECTIVES We investigated whether: (1) DEC can prevent the effects of airway challenge of sensitized mice on lungs and bone marrow, and (2) its effectiveness depends on iNOS/CD95L. METHODS OVA-sensitized BALB/c mice were intranasally challenged for 3 consecutive days, with DEC administered over a 12-, 3-, or 2-day period, ending at the day of the last challenge. We evaluated: (1) airway resistance, cytokine (IFN-gamma, IL-4, IL-5, and eotaxin) production, and pulmonary eosinophil accumulation; and (2) bone marrow eosinophil numbers in vivo and eosinophil differentiation ex vivo. MEASUREMENTS AND MAIN RESULTS DEC effectively prevented the effects of subsequent challenges on: (1) airway resistance, Th1/Th2 cytokine production, and pulmonary eosinophil accumulation; and (2) eosinophilopoiesis in vivo and ex vivo. Recovery from unprotected challenges included full responses to DEC during renewed challenges. DEC directly suppressed IL-5-dependent eosinophilopoiesis in naive bone marrow. DEC was ineffective in CD95L-deficient gld mice and in mice lacking iNOS activity because of gene targeting or pharmacological blockade. CONCLUSIONS DEC has a strong impact on pulmonary eosinophilic inflammation in allergic mice, as well as on the underlying hemopoietic response, suppressing the eosinophil lineage by an iNOS/CD95L-dependent mechanism.

Cysteinyl-leukotriene type 1 receptors transduce a critical signal for the up-regulation of eosinophilopoiesis by interleukin-13 and eotaxin in murine bone marrow

IL‐13 and eotaxin play important, inter‐related roles in asthma models. In the lungs, CysLT, produced by the 5‐LO‐LTC4S pathway, mediate some local responses to IL‐13 and eotaxin; in bone marrow, CysLT enhance IL‐5‐dependent eosinophil differentiation. We examined the effects of IL‐13 and eotaxin on eosinophil differentiation. Semi‐solid or liquid cultures were established from murine bone marrow with GM‐CSF or IL‐5, respectively, and the effects of IL‐13, eotaxin, or CysLT on eosinophil colony formation and on eosinophil differentiation in liquid culture were evaluated, in the absence or presence of: a) the 5‐LO inhibitor zileuton, the FLAP inhibitor MK886, or the CysLT1R antagonists, montelukast and MK571; b) mutations that inactivate 5‐LO, LTC4S, or CysLT1R; and c) neutralizing mAb against eotaxin and its CCR3 receptor. Both cytokines enhanced GM‐CSF‐dependent eosinophil colony formation and IL‐5‐stimulated eosinophil differentiation. Although IL‐13 did not induce eotaxin production, its effects were abolished by anti‐eotaxin and anti‐CCR3 antibodies, suggesting up‐regulation by IL‐13 of responses to endogenous eotaxin. Anti‐CCR3 blocked eotaxin completely. The effects of both cytokines were prevented by zileuton, MK886, montelukast, and MK571, as well as by inactivation of the genes coding for 5‐LO, LTC4S, and CysLT1R. In the absence of either cytokine, these treatments or mutations had no effect. These findings provide evidence for: a) a novel role of eotaxin and IL‐13 in regulating eosinophilopoiesis; and b) a role for CysLTRs in bone marrow cells in transducing cytokine regulatory signals.

Leukotriene B4 is essential for selective eosinophil recruitment following allergen challenge of CD4 cells in a model of chronic eosinophilic inflammation

Subcutaneous heat-coagulated egg white implants (EWI) induce chronic, intense local eosinophilia in mice, followed by asthma-like responses to airway ovalbumin challenge. Our goal was to define the mechanisms of selective eosinophil accumulation in the EWI model. EWI carriers were challenged i.p. with ovalbumin and the contributions of cellular immunity and inflammatory mediators to the resulting leukocyte accumulation were defined through cell transfer and pharmacological inhibition protocols. Eosinophil recruitment required Major Histocompatibility Complex Class II expression, and was abolished by the leukotriene B4 (LTB4) receptor antagonist CP 105.696, the 5-lipoxygenase inhibitor BWA4C and the 5-lipoxygenase activating protein inhibitor MK886. Eosinophil recruitment in EWI carriers followed transfer of: a) CD4+ (but not CD4-) cells, harvested from EWI donors and restimulated ex vivo; b) their cell-free supernatants, containing LTB4. Restimulation in the presence of MK886 was ineffective. CC chemokine receptor ligand (CCL)5 and CCL2 were induced by ovalbumin challenge in vivo. mRNA for CCL17 and CCL11 was induced in ovalbumin-restimulated CD4+ cells ex vivo. MK886 blocked induction of CCL17. Pretreatment of EWI carriers with MK886 eliminated the effectiveness of exogenously administered CCL11, CCL2 and CCL5. In conclusion, chemokine-producing, ovalbumin-restimulated CD4+ cells initiate eosinophil recruitment which is strictly dependent on LTB4 production.

Evidence for a regulatory role of α4 – integrins in the maturation of eosinophils generated from the bone marrow in the presence of dexamethasone

Background Although eosinophils co‐express multiple integrin receptors, the contributions of integrins to eosinophil development have not been explored. We previously described extensive aggregation and cytological immaturity in eosinophils developing in bone‐marrow (BM) cultures exposed to dexamethasone. Here we examined the relationship of α4 integrins with these effects of dexamethasone.

5-lipoxygenase-dependent recruitment of neutrophils and macrophages by eotaxin-stimulated murine eosinophils.

The roles of eosinophils in antimicrobial defense remain incompletely understood. In ovalbumin-sensitized mice, eosinophils are selectively recruited to the peritoneal cavity by antigen, eotaxin, or leukotriene(LT)B4, a 5-lipoxygenase (5-LO) metabolite. 5-LO blockade prevents responses to both antigen and eotaxin. We examined responses to eotaxin in the absence of sensitization and their dependence on 5-LO. BALB/c or PAS mice and their mutants (5-LO-deficient ALOX; eosinophil-deficient GATA-1) were injected i.p. with eotaxin, eosinophils, or both, and leukocyte accumulation was quantified up to 24 h. Significant recruitment of eosinophils by eotaxin in BALB/c, up to 24 h, was accompanied by much larger numbers of recruited neutrophils and monocytes/macrophages. These effects were abolished by eotaxin neutralization and 5-LO-activating protein inhibitor MK886. In ALOX (but not PAS) mice, eotaxin recruitment was abolished for eosinophils and halved for neutrophils. In GATA-1 mutants, eotaxin recruited neither neutrophils nor macrophages. Transfer of eosinophils cultured from bone-marrow of BALB/c donors, or from ALOX donors, into GATA-1 mutant recipients, i.p., restored eotaxin recruitment of neutrophils and showed that the critical step dependent on 5-LO is the initial recruitment of eosinophils by eotaxin, not the secondary neutrophil accumulation. Eosinophil-dependent recruitment of neutrophils in naive BALB/c mice was associated with increased binding of bacteria.

G-CSF suppresses allergic pulmonary inflammation, downmodulating cytokine, chemokine and eosinophil production

AIMS Granulocyte Colony-Stimulating Factor (G-CSF), which mobilizes hemopoietic stem cells (HSC), is believed to protect HSC graft recipients from graft-versus-host disease by enhancing Th2 cytokine secretion. Accordingly, G-CSF should aggravate Th2-dependent allergic pulmonary inflammation and the associated eosinophilia. We evaluated the effects of G-CSF in a model of allergic pulmonary inflammation. MAIN METHODS Allergic pulmonary inflammation was induced by repeated aerosol allergen challenge in ovalbumin-sensitized C57BL/6J mice. The effects of allergen challenge and of G-CSF pretreatment were evaluated by monitoring: a) eosinophilia and cytokine/chemokine content of bronchoalveolar lavage fluid, pulmonary interstitium, and blood; b) changes in airway resistance; and c) changes in bone-marrow eosinophil production. KEY FINDINGS Contrary to expectations, G-CSF pretreatment neither induced nor enhanced allergic pulmonary inflammation. Instead, G-CSF: a) suppressed accumulation of infiltrating eosinophils in bronchoalveolar, peribronchial and perivascular spaces of challenged lungs; and b) prevented ovalbumin challenge-induced rises in airway resistance. G-CSF had multiple regulatory effects on cytokine and chemokine production: in bronchoalveolar lavage fluid, levels of IL-1 and IL-12 (p40), eotaxin and MIP-1a were decreased; in plasma, KC, a neutrophil chemoattractant, was increased, while IL-5 was decreased and eotaxin was unaffected. In bone-marrow, G-CSF: a) prevented the increase in bone-marrow eosinophil production induced by ovalbumin challenge of sensitized mice; and b) selectively stimulated neutrophil colony formation. SIGNIFICANCE These observations challenge the view that G-CSF deviates cytokine production towards a Th2 profile in vivo, and suggest that this neutrophil-selective hemopoietin affects eosinophilic inflammation by a combination of effects on lung cytokine production and bone-marrow hemopoiesis.

Prediction of sepsis-related outcomes in neonates through systematic genotyping of polymorphisms in genes for innate immunity and inflammation: a narrative review and critical perspective

CONTEXT AND OBJECTIVE Neonatal sepsis is associated with premature birth and maternal infection. Large-scale studies seek to define markers that identify neonates at risk of developing sepsis. Here, we examine whether the scientific evidence supports systematic use of polymorphism genotyping in cytokine and innate immunity genes, to identify neonates at increased risk of sepsis. DESIGN AND SETTING Narrative literature review conducted at Fernandes Figueira Institute, Brazil. METHODS The literature was searched in PubMed, Embase (Excerpta Medica Database), Lilacs (Literatura Latino-Americana e do Caribe em Ciências da Saúde), SciELO (Scientific Electronic Library Online) and Cochrane Library. From > 400,000 references, 548 were retrieved based on inclusion/exclusion criteria; 22 were selected for detailed analysis after quality assessment. RESULTS The studies retrieved addressed the impact of gene polymorphisms relating to immune mechanisms (most often TNF-a, LT-a, IL-6, IL-1β, IL-1ra, L-selectin, CD14 and MBL) or inflammatory mechanisms (ACE and angiotensin II receptors; secretory PLA2; and hemostatic factors). Despite initial reports suggesting positive associations between specific polymorphisms and increased risk of sepsis, the accumulated evidence has not confirmed that any of them have predictive power to justify systematic genotyping. CONCLUSIONS Sepsis prediction through systematic genotyping needs to be reevaluated, based on studies that demonstrate the functional impact of gene polymorphisms and epidemiological differences among ethnically distinct populations.

Lack of signaling by IL-4 or by IL-4/IL-13 has more attenuating effects on Leishmania amazonensis dorsal skin--than on footpad-infected mice.

Lesion development in tegumentary leishmaniasis is markedly influenced by the inoculation site and the type and number of injected infective forms. This and the yet unclear contribution of Th2 cytokines as susceptibility factors to Leishmania amazonensis infection prompted us to investigate the roles of IL-4, IL-13 and IL-10 on C57BL/6 and BALB/c mice infected in the footpad (paw) or rump with low-dose L. amazonensis purified-metacyclics. Wild-type (WT) mice of either strain developed, in the rump, a single large ulcerated lesion whereas paw lesions never ulcerated and were much smaller in C57BL/6 than in BALB/c mice. However, rump-inoculated IL-4-deficient (IL-4(-/-)) C57BL/6 mice did not develop any visible lesions although parasites remained in the dermis and lymph nodes, even after systemic IL-10-receptor blocking. By comparison, all IL-4(-/-) BALB/c mice developed rump ulcers. Strikingly, only 30% of rump-infected IL-4Rα(-/-) BALB/c mice developed lesions. IL-4(-/-) mice had higher IFN-γ and lower IL-10 and IL-13 levels than WT mice. Paw-infected IL-4Rα(-/-) BALB/c mice developed minimal paw lesions. While other factors contributing to L. amazonensis susceptibility cannot be discounted, our results indicate that absent signalling by IL-4 or by IL-4/IL-13 have more intense attenuating effects on rump than on paw lesions but do not eradicate parasitism.

Essential roles of endogenous glucocorticoids and TNF/TNFR1 in promoting bone-marrow eosinopoiesis in ovalbumin-sensitized, airway-challenged mice

AIMS Stress mechanisms paradoxically contribute to allergic episodes in humans and mice. Glucocorticoids (GC) and interleukin (IL)-5 synergically upregulate murine bone-marrow eosinophil production. Here we explored the role of endogenous GC in allergen-stimulated bone-marrow eosinophil production in ovalbumin-sensitized/challenged mice. MAIN METHODS In BALB/c or C57BL/6 mice, sensitized and intranasally challenged with ovalbumin, we monitored eosinophil numbers in freshly harvested or cultured bone-marrow, and plasma corticosterone levels. Metyrapone (MET) was used to inhibit GC synthesis, and RU486 to block GC actions. In sensitized mice challenged intraperitoneally, we examined the relationship between eosinophilia of bone-marrow and peritoneal cavity, in the absence or presence of RU486. In experiments involving in vivo neutralization of tumor necrosis factor-α (TNF) by specific antibodies, or using mice which lack functional type I TNF receptors (TNFRI), we evaluated the relationship between TNF blockade, corticosterone levels, RU486 or MET treatment and challenge-induced bone-marrow eosinophilia. KEY FINDINGS RU486 or MET pretreatments abolished challenge-induced increases in eosinophil numbers in bone-marrow (in vivo and ex vivo), and in the peritoneal cavity. MET, but not RU486, prevented the challenge-induced increase in corticosterone levels. Challenge-induced bone-marrow eosinophilia and corticosterone surge were abolished in TNFRI-deficient mice. Anti-TNF-treatment very effectively prevented challenge-induced bone-marrow eosinophilia, in the absence of RU486 or MET, but had no independent effect in the presence of either drug. SIGNIFICANCE Endogenous GC was essential for allergen challenge-induced increases in eosinophil numbers inside bone-marrow. This effect required TNF and TNFRI, which suggests an immunoendocrine mechanism.