Ordered mesoporous silicas for potential applications in solid vaccine formulations.

In an effort to develop efficient vaccine formulations, the use of ordered mesoporous silica (SBA-15) as an antigen carrier has been investigated. SBA-15 has required properties such as high surface area and pore volume, including narrow pore size distribution to protect antigens inside its matrix. This study aimed to examine the impact of solvent removal methods, specifically freeze-drying and evaporation on the intrinsic properties of an immunogenic complex. The immunogenic complexes, synthesized and incorporated with BSA, were characterized by various physicochemical techniques. Small Angle X-ray Scattering measurements revealed the characteristic reflections associated to pure SBA-15, indicating the preservation of the silica mesostructured following BSA incorporation and the formation of BSA aggregates within the macropore region. Nitrogen Adsorption Isotherm measurements demonstrated a decrease in surface area and pore volume for all samples, indicating that the BSA was incorporated into the SBA-15 matrix. Fluorescence spectroscopy evidenced that the tryptophan residues in BSA inside SBA-15 or in solution displayed similar spectra, showing the preservation of the aromatic residues' environment. The Circular Dichroism spectra of BSA in both conditions suggest the preservation of its native secondary structure after the encapsulation process. The immunogenic analysis with the detection of anti-BSA IgG did not give any significant difference between the non-dried, freeze-dried or evaporated groups. However, all groups containing BSA and SBA-15 showed results almost three times higher than the groups with pure BSA (control group). These facts indicate that none of the BSA incorporation methods interfered with the immunogenicity of the complex. In particular, the freeze-dried process is regularly used in the pharmaceutical industry, therefore its adequacy to produce immunogenic complexes was proved Furthermore, the results showed that SBA-15 increased the immunogenic activity of BSA.

Crotalphine Attenuates Pain and Neuroinflammation Induced by Experimental Autoimmune Encephalomyelitis in Mice.

Multiple sclerosis (MS) is a demyelinating disease of inflammatory and autoimmune origin, which induces sensory and progressive motor impairments, including pain. Cells of the immune system actively participate in the pathogenesis and progression of MS by inducing neuroinflammation, tissue damage, and demyelination. Crotalphine (CRO), a structural analogue to a peptide firstly identified in Crotalus durissus terrificus snake venom, induces analgesia by endogenous opioid release and type 2 cannabinoid receptor (CB2) activation. Since CB2 activation downregulates neuroinflammation and ameliorates symptoms in mice models of MS, it was presently investigated whether CRO has a beneficial effect in the experimental autoimmune encephalomyelitis (EAE). CRO was administered on the 5th day after immunization, in a single dose, or five doses starting at the peak of disease. CRO partially reverted EAE-induced mechanical hyperalgesia and decreased the severity of the clinical signs. In addition, CRO decreases the inflammatory infiltrate and glial cells activation followed by TNF-α and IL-17 downregulation in the spinal cord. Peripherally, CRO recovers the EAE-induced impairment in myelin thickness in the sciatic nerve. Therefore, CRO interferes with central and peripheral neuroinflammation, opening perspectives to MS control.

Pain and Cellular Migration Induced by Bothrops jararaca Venom in Mice Selected for an Acute Inflammatory Response: Involvement of Mast Cells.

Bothrops jararaca venom (BjV) can induce mast cell degranulation. In order to investigate the role of mast cells and the interference of the host genetic background in the inflammation induced by BjV, we have used mouse strains selected for maximal (AIRmax) or minimal (AIRmin) acute inflammatory response (AIR). Mice were pretreated with an inhibitor of mast cell degranulation, cromolyn (CROM), and injected in footpads or intraperitoneally (i.p.) with BjV. Pain was measured with von Frey hairs, cell migration in the peritoneum by flow cytometry, and reactive oxygen species (ROS) production by chemiluminescence assays. The nociceptive response to BjV was higher in AIRmax than AIRmin mice; however, this difference was abolished by pretreatment with CROM. BjV induced peritoneal neutrophil (CD11b+ GR-1+) infiltration and ROS secretion in AIRmax mice only, which were partially inhibited by CROM. Our findings evidence a role for mast cells in pain, neutrophil migration, and ROS production triggered by BjV in AIRmax mice that are more susceptible to the action of BjV.

The Crotoxin:SBA-15 Complex Down-Regulates the Incidence and Intensity of Experimental Autoimmune Encephalomyelitis Through Peripheral and Central Actions.

Crotoxin (CTX), the main neurotoxin from Crotalus durissus terrificus snake venom, has anti-inflammatory, immunomodulatory and antinociceptive activities. However, the CTX-induced toxicity may compromise its use. Under this scenario, the use of nanoparticle such as nanostructured mesoporous silica (SBA-15) as a carrier might become a feasible approach to improve CTX safety. Here, we determined the benefits of SBA-15 on CTX-related neuroinflammatory and immunomodulatory properties during experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis that replicates several histopathological and immunological features observed in humans. We showed that a single administration of CTX:SBA-15 (54 µg/kg) was more effective in reducing pain and ameliorated the clinical score (motor impairment) in EAE animals compared to the CTX-treated EAE group; therefore, improving the disease outcome. Of interest, CTX:SBA-15, but not unconjugated CTX, prevented EAE-induced atrophy and loss of muscle function. Further supporting an immune mechanism, CTX:SBA-15 treatment reduced both recruitment and proliferation of peripheral Th17 cells as well as diminished IL-17 expression and glial cells activation in the spinal cord in EAE animals when compared with CTX-treated EAE group. Finally, CTX:SBA-15, but not unconjugated CTX, prevented the EAE-induced cell infiltration in the CNS. These results provide evidence that SBA-15 maximizes the immunomodulatory and anti-inflammatory effects of CTX in an EAE model; therefore, suggesting that SBA-15 has the potential to improve CTX effectiveness in the treatment of MS.

Mice Selected for Acute Inflammation Present Altered Immune Response during Pristane-Induced Arthritis Progression.

Mouse lines selected for maximal (AIRmax) or minimal acute inflammatory reaction (AIRmin) were used to characterize the immune response and the influence of genetic background during pristane-induced arthritis (PIA). Susceptible AIRmax mice demonstrated exacerbated cellular profiles during PIA, with intense infiltration of lymphocytes, as well as monocytes/macrophages and neutrophils, producing higher levels of IL-1ß, IFN-γ, TNF-α, IL-10, total IgG3, and chemokines. Resistant AIRmin mice controlled cell activation more efficiently than the AIRmax during arthritis progression. The weight alterations of the spleen and thymus in the course of PIA were observed. Our data suggest that selected AIRmax cellular and genetic immune mechanisms contribute to cartilage damage and arthritis severity, evidencing many targets for therapeutic actions.

Germline control of somatic Kras mutations in mouse lung tumors.

Somatic KRAS mutations are common in human lung adenocarcinomas and are associated with worse prognosis. In mice, Kras is frequently mutated in both spontaneous and experimentally induced lung tumors, although the pattern of mutation varies among strains, suggesting that such mutations are not random events. We tested if the occurrence of Kras mutations is under genetic control in two mouse intercrosses. Codon 61 mutations were prevalent, but the patterns of nucleotide changes differed between the intercrosses. Whole genome analysis with SNPs in (A/J x C57BL/6)F4 mice revealed a significant linkage between a locus on chromosome 19 and 2 particular codon 61 variants (CTA and CGA). In (AIRmax × AIRmin) F2 mice, there was a significant linkage between SNPs located on distal chromosome 6 (around 135 Mbp) and the frequency of codon 61 mutation. These results reveal the presence of two loci, on chromosomes 6 and 19, that modulate Kras mutation frequency in different mouse intercrosses. These findings indicate that somatic mutation frequency and type are not simple random events, but are under genetic control.

Impaired expression of CXCL5 and matrix metalloproteinases in the lungs of mice with high susceptibility to Streptococcus pneumoniae infection.

INTRODUCTION: Streptococcus pneumoniae colonizes the nasopharynx of healthy individuals establishing a commensal relationship with the host. In some conditions, bacteria invade the lower respiratory tract and innate immune responses are crucial to avoid diseases such as pneumonia, sepsis, or meningitis. METHODS: Here, we compared the susceptibility to pneumococcal respiratory infection of two outbred mouse lines, AIRmin and AIRmax, selected for low or high acute inflammatory responses, respectively. RESULTS: AIRmin mice showed increased susceptibility to infection with different pneumococcal serotypes, when compared to AIRmax. Significant higher numbers of alveolar macrophages expressing the CD206 mannose receptor were observed in AIRmin mice when compared to AIRmax mice. Despite this difference, secretion of several cytokines and chemokines in the respiratory tract of AIRmin and AIRmax mice, after infection, was similar. The only exception was CXCL5, which was highly induced after pneumococcal infection in AIRmax mice but not in AIRmin mice. Reduced expression of the matrix metalloproteinases (MMP) 2, 3, 8, and 9, as well as reduced activities of MMPs were also observed in the lungs of AIRmin mice, after infection. Such impaired responses may have contributed to the low influx of neutrophils observed in the airways of these mice. Finally, high percentages of macrophages and neutrophils in apoptosis or necrosis, at the site of infection, were also observed in AIRmin mice, suggesting that leukocyte functionality is also compromised. CONCLUSIONS: Our results indicate that CXCL5 and MMPs contribute to the resistance to pneumococcal infection in mice.

Slc11a1 (Nramp-1) gene modulates immune-inflammation genes in macrophages during pristane-induced arthritis in mice.

OBJECTIVE AND DESIGN: Pristane-induced arthritis (PIA) in AIRmax mice homozygous for Slc11a1 R and S alleles was used to characterize the influence of Slc11a1 gene polymorphism on immune responses during disease manifestation. Previous reports demonstrated that the presence of the Slc11a1 S allele increased the incidence and severity of PIA in AIRmax SS , suggesting that this gene could interact with inflammatory loci to modulate PIA. We investigated the effects of Slc11a1 alleles on the activation of phagocytes during PIA. TREATMENT: Mice were injected intraperitoneally with two doses of 0.5 mL of mineral oil pristane at 60-day intervals. Arthritis development was accompanied for 180 days. RESULTS: AIRmax SS mice showed differential peritoneal macrophage gene expression profiles during PIA, with higher expression and production of H2O2, NO, IL-1ß, IL-6, TNF-α, and several chemokines. The presence of the Slc11a1 R allele, on the other hand, diminished the intensity of macrophage activation, restricting arthritis development. CONCLUSION: Our data demonstrated the fine-tuning roles of Slc11a1 alleles modulating macrophage activation, and consequent PIA susceptibility, in those mouse lines.

Trypanosoma cruzi infection in genetically selected mouse lines: genetic linkage with quantitative trait locus controlling antibody response.

Trypanosoma cruzi infection was studied in mouse lines selected for maximal (AIRmax) or minimal (AIRmin) acute inflammatory reaction and for high (HIII) or low (LIII) antibody (Ab) responses to complex antigens. Resistance was associated with gender (females) and strain-the high responder lines AIRmax and HIII were resistant. The higher resistance of HIII as compared to LIII mice extended to higher infective doses and was correlated with enhanced production of IFN-γ and nitric oxide production by peritoneal and lymph node cells, in HIII males and females. We also analyzed the involvement of previously mapped Ab and T. cruzi response QTL with the survival of Selection III mice to T. cruzi infections in a segregating backcross [F1(HIII×LIII) ×LIII] population. An Ab production QTL marker mapping to mouse chromosome 1 (34.8 cM) significantly cosegregated with survival after acute T. cruzi infections, indicating that this region also harbors genes whose alleles modulate resistance to acute T. cruzi infection.

Pristane-induced arthritis loci interact with the Slc11a1 gene to determine susceptibility in mice selected for high inflammation.

AIRmax (maximal inflammation) and AIRmin (minimal inflammation) mice show distinct susceptibilities to pristane-induced arthritis (PIA). The Slc11a1 gene, which regulates macrophage and neutrophil activity, is involved in this infirmity. AIRmax (SS) mice homozygous for the non-functional Slc11a1 S (gly169asp) allele obtained by genotype-assisted crosses from AIRmax and AIRmin mice are more susceptible than mice homozygous for the Slc11a1 resistant (R) allele. The present work sought to identify the quantitative trait loci (QTL) regulating PIA and to examine the interactions of these QTL with Slc11a1 alleles in modulating PIA. Mice were given two ip injections of 0.5 mL pristane at 60 day intervals, and the incidence and severity of PIA was scored up to 160 days. Genome-wide linkage studies were performed to search for arthritis QTL in an F2 (AIRmax × AIRmin, n = 290) population. Significant arthritis QTL (LODscore>4) were detected on chromosomes 5 and 8, and suggestive QTL on chromosomes 7, 17 and 19. Global gene expression analyses performed on Affymetrix mouse 1.0 ST bioarrays (27k genes) using RNA from arthritic or control mice paws showed 419 differentially expressed genes between AIRmax and AIRmin mice and demonstrated significantly (P<0.001) over-represented genes related to inflammatory responses and chemotaxis. Up-regulation of the chemokine genes Cxcl1, Cxcl9, Cxcl5, Cxcl13 on chromosome 5 was higher in AIRmax(SS) than in the other lines. Macrophage scavenger receptor 1 and hemeoxigenase (decycling) 1 genes on chromosome 8 were also expressed at higher levels in AIRmax(SS) mice. Our results show that the gene expression profiles of the two arthritis QTL (on chromosomes 5 and 8) correlate with Slc11a1 alleles, resulting in enhanced AIRmax(SS) mice susceptibility to PIA.

The role of leukotriene B4 in early stages of experimental paracoccidioidomycosis induced in phenotypically selected mouse strains.

Paracoccidioidomycosis is a human systemic mycosis caused by the fungus Paracoccidioides brasiliensis. The mechanisms involved in innate immune response to this fungus are not fully elucidated. Leukotrienes are known to be critical for the clearance of various microorganisms, mainly by mediating the microbicidal function of phagocytes. We investigated the involvement of leukotriene B4 in the early stages of experimental paracoccidioidomycosis, which was induced by intratracheal inoculation of the fungus in selected mouse lines. The mouse lines utilized were produced through bi-directional phenotypic selection, endowed with maximal or minimal acute inflammatory reactivity, and designated AIRmax and AIRmin, respectively. AIRmax mice were more resistant to the infection, which was demonstrated by reduced lung fungal loads. However, the two lines produced similar amounts of leukotriene B4, and pharmacological inhibition of this mediator provoked similar fungal load increases in the two lines. The lower fungal load in the AIRmax mice was associated with a more effective inflammatory response, which was characterized by enhanced recruitment and activation of phagocytic cells and an increased production of activator cytokines. This process resulted in an increased release of fungicidal molecules and a diminution of fungal load. In both lines, leukotriene production was associated with a protective response in the lung that was consequent to the effect of this eicosanoid on the influx and activation of phagocytes.

Distinct early inflammatory events during ear tissue regeneration in mice selected for high inflammation bearing Slc11a1 R and S alleles

High inflammatory AIRmax mice homozygous for Slc11a1 R and S alleles were produced. AIRmaxSS mice showed faster ear tissue regeneration than AIRmaxRR mice, suggesting that the Sallele favored tissue restoration. Here, we investigated the gene expression profiles and the inflammatory reactions of AIRmaxRR and AIRmaxSS mice during the initial phase of ear tissue regeneration. We observed superior levels of analysis of wound myeloperoxidase and edema inAIRmaxSS mice, although similar cell influx was verified in both lines. Of the genes, 794 were up- and 674 down-regulated in AIRmaxRR, while 735 genes were found to be up- and 1616 down-regulated in AIRmaxSS mice 48 h after punch. Both mouse lines showed significant over-represented genes related to cell proliferation; however AIRmaxSS displayed up-regulation of inflammatory response genes. Quantitative PCR experiments showed higher expressions of Tgfb1, Dap12 and Trem1 genes in AIRmaxSS mice. These results indicate that Slc11a1 gene modulated the early inflammatory events of ear tissue regeneration.

Distinct early inflammatory events during ear tissue regeneration in mice selected for high inflammation bearing Slc11a1 R and S alleles.

High inflammatory AIRmax mice homozygous for Slc11a1 R and S alleles were produced. AIRmax(SS) mice showed faster ear tissue regeneration than AIRmax(RR) mice, suggesting that the S allele favored tissue restoration. Here, we investigated the gene expression profiles and the inflammatory reactions of AIRmax(RR) and AIRmax(SS) mice during the initial phase of ear tissue regeneration. We observed superior levels of analysis of wound myeloperoxidase and edema in AIRmax(SS) mice, although similar cell influx was verified in both lines. Of the genes, 794 were up- and 674 down-regulated in AIRmax(RR), while 735 genes were found to be up- and 1616 down-regulated in AIRmax(SS) mice 48 h after punch. Both mouse lines showed significant over-represented genes related to cell proliferation; however AIRmax(SS) displayed up-regulation of inflammatory response genes. Quantitative PCR experiments showed higher expressions of Tgfb1, Dap12 and Trem1 genes in AIRmax(SS) mice. These results indicate that Slc11a1 gene modulated the early inflammatory events of ear tissue regeneration.

Gene expression profiles of bone marrow cells from mice phenotype-selected for maximal or minimal acute inflammations: searching for genes in acute inflammation modifier loci.

Two mouse lines were phenotype-selected for maximum (AIRmax) or minimum (AIRmin) acute inflammation responses to polyacrylamide bead (Biogel) injection. These lines differ in terms of bone marrow granulopoiesis, neutrophil resistance to apoptosis, and inflammatory cytokine production during acute inflammation responses. We compared gene expression profiles in bone marrow cells (BMC) of AIRmax and AIRmin mice during acute inflammatory reactions. The BMC from femurs were recovered 24 hr after subcutaneous injections of Biogel. Global gene expression analysis was performed on CodeLink Bioarrays (36K genes) using RNA pools of BMC from both control and treated AIRmax and AIRmin mice. Differentially expressed genes were statistically established and the over-represented gene ontology biological process categories were identified. Upregulations of about 136 and 198 genes were observed in the BMC of Biogel-treated AIRmax and AIRmin mice, respectively, but 740 genes were found to be downregulated in AIRmin mice compared with 94 genes in AIRmax mice. The over-represented biological themes of the differently expressed genes among AIRmax and AIRmin mice represent inflammatory response, signal transduction, cell proliferation and immune cell chemotaxis. We were able to demonstrate a broad downmodulation of gene transcripts in BMC from AIRmin mice during acute inflammation, and significant differentially expressed genes colocalized with previously mapped regions for inflammation-related phenotypes in chromosomes 1, 3, 6 and 11.

Aryl hydrocarbon receptor polymorphism modulates DMBA-induced inflammation and carcinogenesis in phenotypically selected mice.

We tested the role of aryl hydrocarbon receptor (Ahr) gene polymorphism in the inflammatory response and in skin and lung tumorigenesis in 2 lines of mice phenotypically selected for maximum or minimum acute inflammatory reaction (AIRmax and AIRmin, respectively). Following 7,12-dimethylbenz[a]anthracene (DMBA) treatment, AIRmin but not AIRmax mice showed early skin reactions and eventually developed malignant skin tumors and lung adenocarcinomas. In skin tissue, transcript levels of IL1beta, Tnf, Il6, Tgfbeta1 and Cyp1b1 genes were upregulated in AIRmin but not AIRmax mice, consistent with the inflammatory responses to the carcinogen. These findings appeared to be related to the homozygosity status of the Ahr functional A375V polymorphism, which influences the binding capability of the receptor for DMBA: the 375A allele, encoding the high-affinity ligand-binding receptor (Ahr(b1)), segregated in AIRmin mice, whereas AIRmax mice carried the 375V, corresponding to the low-affinity binding receptor (Ahr(d)), to DMBA. The differential segregation of Ahr functional Ahr(d)versus Ahr(b1) alleles in AIRmax and AIRmin suggests a role for the Ahr gene in the control of inflammatory responsiveness and tumor development of these mouse lines.

Bothrops jararaca venom (BjV) induces differential leukocyte accumulation in mice genetically selected for acute inflammatory reaction: the role of host genetic background on expression of adhesion molecules and release of endogenous mediators.

The dynamics of the local inflammatory events induced by Bothrops jararaca venom (BjV) inoculation in footpad of mice genetically selected for maximal (AIRmax) and minimal (AIRmin) acute inflammatory reactivity (AIR) was investigated. The BjV injection induced a marked inflammatory cell infiltrate with predominance of neutrophils, with increased blood cell numbers before its accumulation, suggesting a stimulatory action of BjV on mechanisms of cell mobilization from bone marrow. The process of cell migration is regulated by different cell-adhesion molecules (CAM). Our results showed that neutrophil cells from both lines had the same pattern of response concerning CAMs expression, presenting the involvement of l-selectin, Mac-1 and PECAM-1 adhesion molecules in BjV-induced neutrophil accumulation. The effect of BjV on the release of pro-inflammatory cytokines and chemokines related with cellular migration was also studied and IL-1beta, IL-6, TNF-alpha and MIP-2 levels could be detected after venom injection. The AIRmax mice were shown to be more responsive than AIRmin with respect to leukocyte influx, expression of MIP-2 and release of IL-1beta and IL-6. These results demonstrate the importance of host genetic background in the local response and the involvement of alleles accumulated in AIRmax mice in the inflammatory events induced by BjV.

Bothrops jararaca venom (BjV) induces differential leukocyte accumulation in mice genetically selected for acute inflammatory reaction: The role of host genetic background on expression of adhesion molecules and release of endogenous mediators

The dynamics of the local inflammatory events induced by Bothrops jararaca venom (BjV) inoculation in footpad of mice genetically selected for maximal (AIRmax) and minimal (AIRmin) acute inflammatory reactivity (AIR) was investigated. The BjV injection induced a marked inflammatory cell infiltrate with predominance of neutrophils, with increased blood cell numbers before its accumulation, suggesting a stimulatory action of BjV on mechanisms of cell mobilization from bone marrow. The process of cell migration is regulated by different cell-adhesion molecules (CAM). Our results showed that neutrophil cells from both lines had the same pattern of response concerning CAMs expression, presenting the involvement of l-selectin, Mac-1 and PECAM-1 adhesion molecules in BjV-induced neutrophil accumulation. The effect of BjV on the release of pro-inflammatory cytokines and chemokines related with cellular migration was also studied and IL-1â, IL-6, TNF-á and MIP-2 levels could be detected after venom injection. The AIRmax mice were shown to be more responsive than AIRmin with respect to leukocyte influx, expression of MIP-2 and release of IL-1â and IL-6. These results demonstrate the importance of host genetic background in the local response and the involvement of alleles accumulated in AIRmax mice in the inflammatory events induced by BjV.

Rabies virus glycoprotein expression in Drosophila S2 cells. I. Functional recombinant protein in stable co-transfected cell line.

Recombinant rabies virus glycoprotein (rRVGP) was expressed in Drosophila melanogaster Schneider 2 (S2) cells. The cDNA encoding the entire RVGP gene was cloned in an expression plasmid under the control of the constitutive actin promoter (Ac), which was co-transfected into S2 cells together with a hygromycin selection plasmid. Selected S2 cell populations (S2AcRVGP) had a decreased ability to grow and consume substrates, when compared to the non-transfected cells (S2). They were shown, by PCR, to express the RVGP gene and mRNA and, by immunoblotting, to synthesize the rRVGP in its expected molecular mass of 65 kDa. ELISA kinetic studies showed the rRVGP expression in cell lysates and supernatants attaining concentrations of 300 microg/L. By flow cytometry analysis, about 30% of the cells in the co-transfected populations were shown to express the rRVGP. Cell populations selected by limiting dilution expressed higher rRVGP yields. Mice immunized with rRVGP were shown to synthesize antibodies against rabies virus and be protected against experimental infection with rabies virus. The data presented here show that S2 cells can be suitable hosts for the rRVGP expression, allowing its synthesis in a high degree of physical and biological integrity.

Quantitative trait loci in Chromosomes 3, 8, and 9 regulate antibody production against Salmonella flagellar antigens in the mouse.

Two mouse lines were produced by bidirectional selection according to the high (HIII) or low (LIII) antibody responsiveness against Salmonella flagellar antigens (Selection III). In the present work we conducted a genomewide scan to map the quantitative trait loci (QTL) involved in the antibody response regulation in these selected mice. HIII and LIII genomes were screened with microsatellite markers and those found polymorphic between the lines (146) were used for linkage analysis in F2 (HIII x LIII) intercross. Simple interval mapping analysis was performed using Mapmanager QTX software. Three highly significant QTL linked to antibody production against Salmonella flagellar antigens have been demonstrated in Chromosomes 3, 8, and 9. HIII and LIII lines differ in the resistance to several diseases, therefore, the relevance of these QTL with the genetic factors involved in infections, autoimmunity, and neoplastic disease progression is discussed.

Convergent alteration of granulopoiesis, chemotactic activity, and neutrophil apoptosis during mouse selection for high acute inflammatory response.

Neutrophil homeostasis was investigated in two mouse lines, AIRmax and AIRmin, genetically selected for high or low acute inflammatory response (AIR) and compared with unselected BALB/c mice. Mature neutrophil phenotype and functions appeared similar in the three mouse lines. However, an unprecedented phenotype was revealed in AIRmax animals characterized by a high neutrophil production in bone marrow (BM), a high number of neutrophils in blood, a high concentration of chemotactic agents in acrylamide-induced inflammatory exudates, and an increased resistance of locally infiltrated neutrophils to spontaneous apoptosis. In vitro, BM production of neutrophils and eosinophils was accompanied by an unusual high up-regulation of cytokine receptors as assessed by antibodies to CD131, which bind the common beta chain of receptors to interleukin (IL)-3, IL-5, and granulocyte macrophage-colony stimulating factor. An accelerated neutrophil maturation was also observed in response to all-trans retinoic acid. Several candidate genes can be proposed to explain this phenotype. Yet, more importantly, the results underline that genetic selection, based on the degree of AIR and starting from a founding population resulting from the intercross of eight inbred mouse lines, which display a continuous range of inflammatory responses, can lead to the convergent selection of alleles affecting neutrophil homeostasis. Similar gene combinations may occur in the human with important consequences in the susceptibility to inflammatory or infectious diseases and cancer.