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.

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.

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-?, TNF-a, 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.

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-?, TNF-a, 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.

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. (AU)

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.

Distinct gene expression profiles provoked by polyacrylamide beads (Biogel) during chronic and acute inflammation in mice selected for maximal and minimal inflammatory responses.

OBJECTIVE AND DESIGN: AIRmax and AIRmin mice differ in their local acute inflammatory reactions to polyacrylamide beads (Biogel). These lines were developed to identify genes that affect the intensity of the acute inflammatory response (AIR) and to investigate the cellular and molecular mechanisms of acute inflammation. Although these lines are well established, differences in their responses to chronic inflammatory Biogel exposure have not yet been described. We investigated whether the selective process that modified the acute inflammatory responses in these animals also affected the development of their chronic inflammatory responses. RESULTS: Inflammatory exudate cell infiltration was more intense in AIRmax than AIRmin mice at both 48 h and 30 days. Genes involved in signal transduction and immune/inflammatory responses were differentially expressed in the treated skin of AIRmax and AIRmin mice, and divergent expression of some acute inflammatory response genes was detected up to 30 days post-Biogel. However, distinct expression of several pro and anti-inflammatory response genes in both periods was observed. CONCLUSION: These results indicate that the selective process for acute inflammation affected the development of chronic inflammatory responses to Biogel, suggesting common genetic control.

Distinct gene expression profiles provoked by polyacrylamide beads (Biogel) during chronic and acute inflammation in mice selected for maximal and minimal inflammatory responses

AIRmax and AIRmin mice differ in their local acute inflammatory reactions to polyacrylamide beads (Biogel). These lines were developed to identify genes that affect the intensity of the acute inflammatory response (AIR) and to investigate the cellular and molecular mechanisms of acute inflammation. Although these lines are well established, differences in their responses to chronic inflammatory Biogel exposure have not yet been described. We investigated whether the selective process that modified the acute inflammatory responses in these animals also affected the development of their chronic inflammatory responses. Inflammatory exudate cell infiltration was more intense in AIRmax than AIRmin mice at both 48 h and 30 days. Genes involved in signal transduction and immune/inflammatory responses were differentially expressed in the treated skin of AIRmax and AIRmin mice, and divergent expression of some acute inflammatory response genes was detected up to 30 days post-Biogel. However, distinct expression of several pro and anti-inflammatory response genes in both periods was observed. These results indicate that the selective process for acute inflammation affected the development of chronic inflammatory responses to Biogel, suggesting common genetic control

Acute Inflammation Loci Are Involved in Wound Healing in the Mouse Ear Punch Model.

Significance: Molecular biology techniques are being used to aid in determining the mechanisms responsible for tissue repair without scar formation. Wound healing is genetically determined, but there have been few studies that examine the genes responsible for tissue regeneration in mammals. Research using genetic mapping is extremely important for understanding the molecular mechanisms involved in the different phases of tissue regeneration. This process is complex, but an early inflammatory phase appears to influence lesion closure, and the present study demonstrates that acute inflammation loci influence tissue regeneration in mice in a positive manner. Recent Advances: Mapping studies of quantitative trait loci (QTL) have been undertaken in recent years to examine candidate genes that participate in the regeneration phenotype. Our laboratory has identified inflammation modifier QTL for wound healing. Mouse lines selected for the maximum (AIRmax) or minimum (AIRmin) acute inflammatory reactivity (AIR) have been used to study not only the tissue repair but also the impact of the genetic control of inflammation on susceptibility to autoimmune, neoplasic, and infectious diseases. Murphy Roths Large and AIRmax mice are exclusive in their complete epimorphic regeneration, although middle-aged inbred mice may also be capable of healing. Critical Issues: Inflammatory reactions have traditionally been described in the literature as negative factors in the process of skin injury closure. Inflammation is exacerbated due to the early release of mediators or the intense release of factors that cause cell proliferation after injury. The initial release of these factors as well as the clean-up of the lesion microenvironment are both crucial for following events. In addition, the activation and repression of some genes related to the regeneration phenotype may modulate lesion closure, demonstrating the significance of genetic studies to better understand the mechanisms involved in the initiation of wound repair processes. Future Directions: The pleiotropic effects of the QTL are important in the identification of the genes responsible for tissue repair processes, especially when combined with global gene expression research. Microarray analysis complements the biological information obtained in QTL mapping, making this tool essential for gene identification. This approach will allow the investigation of future targets for therapeutic wound healing treatments.

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.

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.