Nancy Starobinas

Innate resistance to infection by intracellular bacterial pathogens differs in mice selected for maximal or minimal acute inflammatory response

The intensity of nonspecific immune reaction and the host resistance to facultative intracellular pathogens are found to be associated in lines of mice selected for maximal (AIRmax) or minimal (AIRmin) acute inflammatory reactivity. AIRmax are more resistant than AIRmin mice to Salmonella typhimurium and Listeria monocytogenes infection, the differences between lines in LD50 being > 1000 and 100 times, respectively. This difference was shown to be related to the initial bacterial containment at the infectious focus, and to the control of bacterial multiplication in the spleen during the 1st week after s.  c. inoculation of the bacteria. Specific immune responses were not deeply affected by the selective process: antibody production and delayed‐type hypersensitivity were both of similar intensity in AIRmax and AIRmin mice. The differential susceptibility to infection seems independent of the Nramp‐1 locus polymorphism; therefore, these two lines represent a powerful model for investigating the role of other genetic loci regulating the nonspecific immunity effectors in the course of infectious diseases.

Pulmonary adenoma susceptibility 1 ( Pas1 ) locus affects inflammatory response

Two outbred mouse lines, phenotypically selected for differential subcutaneous (s.c.) acute inflammatory response (AIR), were analysed for urethane-induced lung inflammatory response and susceptibility to lung tumorigenesis. AIRmin mice, which show a low response to s.c. acute inflammation, developed a persistent subacute lung inflammatory response and a 40-fold higher lung tumor multiplicity than did AIRmax mice, which are selected for high response to s.c. acute inflammation and showed a transient lung inflammatory response. A highly significant linkage disequilibrium pattern was observed in AIRmax and AIRmin mice at marker alleles located within a 452-kb pulmonary adenoma susceptibility 1 (Pas1) locus region, thus defining the location of gene candidacy for inflammatory response and for the biological effects of Pas1 in this region. AIRmin and AIRmax mice segregated by descent the Pas1s and Pas1r alleles, respectively, providing evidence for the involvement of the Pas1 locus in the inflammatory response. The 452-kb region contains Kras2 and four additional genes, including the lymphoid-restricted membrane protein (Lrmp) gene, whose Pro→Leu nonconservative variation was linked with inflammatory response and Pas1 allelotype. These results provide a model to explore the mechanism underlying inherited predisposition to lung cancer in the context of a link to inflammation.

Local inflammatory reaction induced by Bothrops jararaca venom differs in mice selected for acute inflammatory response.

Bothrops jararaca venom (BjV) causes severe systemic and local reactions, characterized by an acute inflammatory reaction with accumulation of leukocytes and release of endogenous mediators. The systemic and local effects of BjV were compared in lines of mice genetically selected for maximal (AIR(max)) or minimal (AIR(min)) acute inflammatory reactivity (AIR). The systemic reaction was evaluated by LD(50) and the local reaction by edema formation, cellular influx, release of PGE(2), NO and H(2)O(2) and the production of the pro-inflammatory cytokines IL-6, Tumor necrosis factor-alpha (TNF-alpha) and IFN-gamma. Both mouse lines were equally susceptible to the lethal effects of the venom showing similar LD(50) but differed significantly in terms of the local inflammatory reaction. Footpad edema and leukocyte influx in the peritoneum after BjV inoculation was higher in AIR(max) compared to AIR(min), BALB/c or outbred Swiss mice. Coincidently, higher levels of the soluble mediators PGE(2), IFN-gamma and TNF-alpha were detected in the inflammatory exudate induced by BjV in AIR(max) mice. Cytokines levels were correlated to in vitro NO and H(2)O(2) production. The results demonstrate that the genetic factors selected in AIR(max) and AIR(min) lines of mice interfere in the control of the acute local reaction triggered by BjV venom.

Slc11a1 (formerly NRAMP1 ) gene modulates both acute inflammatory reactions and pristane-induced arthritis in mice

Mice selected for the maximum acute inflammatory reaction (AIRmax) are highly susceptible to pristane-induced arthritis (PIA), whereas mice selected for the minimum response (AIRmin) are resistant. These lines show distinct patterns of leukocyte infiltration and R and S allele frequency disequilibrium of the solute carrier family 11a member 1 (Slc11a1) gene. In order to study the interactions of the Slc11a1 R and S alleles with the inflammation modulating Quantitative Trait Loci (QTL) during PIA development, homozygous AIRmaxRR, AIRmaxSS, AIRminRR and AIRminSS lines were produced by genotype-assisted breedings. These mice received two intraperitoneal injections of 0.5 ml pristane at 60-day intervals, and the subsequent development of arthritis was assessed for 210 days. Cytokine-secreting cell profiles were investigated using enzyme-linked immunospot. Arthritis incidence in AIRmaxRR mice reached 29%, whereas PIA incidence in AIRmaxSS mice was 70% by day 180. AIRminRR mice were resistant, whereas 13.3% of AIRminSS mice became arthritic. The presence of the defective S allele also increased arthritis severity, although acute inflammation was higher in mice bearing the R allele. A predominant Th0/Th2-type response in Slc11a1SS mice was observed. These results indicate that Slc11a1 is a strong candidate for the QTL modulating acute inflammation and for PIA.

Slc11a1 (Nramp1) alleles interact with acute inflammation loci to modulate wound-healing traits in mice

Lines of mice were obtained by selective breeding for maximum (AIRmax) or minimum (AIRmin) acute inflammation. They present distinct neutrophil influx and show frequency disequilibrium of the solute carrier family 11a member 1(Slc11a1) alleles. This gene is involved in ion transport at the endosomes within macrophages and neutrophils, interfering in their activation. Homozygous AIRmax and AIRmin sublines for the Slc11a1 gene were produced to examine the interaction of this gene with the acute inflammatory loci. The present work investigated wound-healing traits in AIRmax and AIRmin mice, in F1 and F2 intercrosses, and in Slc11a1 sublines. Two-millimeter ear punches were made in the mice and hole closure was measured during 40 days. AIRmax mice demonstrated significant tissue repair while AIRmin mice did not. Significant differences between the responses of male and female mice were also observed. Wound-healing traits demonstrated a correlation with neutrophil influx in F2 populations. AIRmaxSSshowed higher ear-wound closure than AIRmaxRR mice, suggesting that the Slc11a1S allele favored ear tissue repair. QTL analysis has detected two inflammatory loci modulating ear wound healing on chromosomes 1 and 14. These results suggest the involvement of the acute inflammation modifier QTL in the wound-healing phenotype.

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 IL1β, Tnf, Il6, Tgfβ1 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 (Ahrb1), segregated in AIRmin mice, whereas AIRmax mice carried the 375V, corresponding to the low‐affinity binding receptor (Ahrd), to DMBA. The differential segregation of Ahr functional Ahrdversus Ahrb1 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.

Genetic Selection For High Acute Inflammatory Response Confers Resistance To Lung Carcinogenesis In The Mouse

Mice selected for a high acute inflammatory response (AIRmax) are resistant to chemically induced lung tumorigenesis, whereas the low responders (AIRmin) are susceptible. In urethane-treated mice, anti-inflammatory drugs increased the tumor incidence in AIRmax but not AIRmin mice, and an inverse correlation (P<.001) between the degree of acute inflammatory response (AIR) and lung tumorigenesis was found in an F2 (AIRmax×AIRmin) intercross population. The results provide evidence for the involvement of lung tumor modifier loci in AIR regulation and implicate AIR quantitative trait loci in the inherited predisposition to lung cancer.

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 × 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.

Involvement of antibody production quantitative trait loci in the susceptibility to pristane-induced arthritis in the mouse

Mice obtained by bidirectional selective breeding for high (HIII) or low (LIII) antibody (Ab) production are resistant or extremely susceptible to pristane-induced arthritis (PIA), respectively. Several quantitative trait loci regulating Ab production (Ab QTL) have been mapped in these lines, which were used to investigate the influence of these Ab QTL in PIA. Parental HIII and LIII mice and their F1 and F2 intercrosses were injected twice with pristane, and arthritis was observed for 200 days. In LIII mice PIA was more severe and incidence was 100% at day 105, while F1 and F2 mice showed intermediate values. HIII mice were totally resistant. Microsatellite polymorphisms of Ab QTL were analysed and D3Mit100 alleles cosegregated significantly with PIA incidence, severity and onset in F2 intercross mice, while the other four markers showed suggestive values. Results indicate colocalization of QTL for Ab production and PIA susceptibility. Moreover, the different cytokine and IgG isotype profiles observed in HIII and LIII lines after PIA induction are useful to candidate genes endowed with the regulation of the Ab production and arthritis phenotypes.

Genetic Control of IL-1β 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-1β 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-1β (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.