Genetic heterogeneity of inflammatory response and skin tumorigenesis in phenotypically selected mouse lines

Non-inbred AIR (AIRmax, AIRmin) and Car (Car-S, Car-R) mouse lines were generated from the same eight inbred mice through bidirectional selective breeding for acute inflammatory response and for susceptibility to two-stage skin tumorigenesis, respectively. Because AIR lines also showed a differential predisposition to skin tumorigenesis and Car lines differed in the extent of inflammatory response, we carried out genome-wide association studies using SNP arrays to identify the genetic elements affecting skin tumor susceptibility and inflammatory response in AIR and Car lines. We found that the phenotypic outcome reflects a specific genetic profile in each mouse line, suggesting that distinct genetic elements, selected by differential genetic drifts, and exerting pleiotropic effects in each mouse population, control the skin tumor susceptibility and inflammatory response phenotypes. These findings point to the complex link between skin tumor susceptibility and inflammatory response in mice

Genetic control of IL-1 beta production and inflammatory response by the mouse Irm1 locus

Genome-wide linkage analysis using single nucleotide polymorphism arrays was carried out in pedigrees of mice differing in the extent of acute inflammatory response (AIRmax or AIRmin). The AIR phenotype was determined by quantifying the number of infiltrating cells in the 24-h exudate induced by Biogel P-100 s.c. injection and by ex vivo IL-1beta production by leukocytes stimulated with LPS and ATP. We mapped the major inflammatory response modulator 1 locus on chromosome 7, at the 1-logarithm of odds (LOD) confidence interval from 116.75 to 139.75 Mb, linked to the number of infiltrating cells (LOD = 3.61) through the production of IL-1beta (LOD = 9.35). Of several interesting candidate genes mapping to the inflammatory response modulator 1 locus, 28 of these were differentially expressed in the bone marrow of AIRmax and AIRmin mice. These findings represent a step toward the identification of the genes underlying this complex phenotype

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.