Genetic linkage analysis identifies Pas1 as the common locus modulating lung tumorigenesis and acute inflammatory response in mice.

Selective breeding for the acute inflammatory response (AIR) generated two mouse lines characterized by maximum (AIRmax) and minimum (AIRmin) responses, explained by the additive effect of alleles differentially fixed in quantitative trait loci (QTLs). These mice also differ in their susceptibility to lung tumorigenesis, raising the possibility that the same loci are involved in the control of both phenotypes. To map the QTLs responsible for the different phenotypes, we carried out a genome-wide linkage analysis using single-nucleotide polymorphism arrays in a pedigree consisting of 802 mice, including 693 (AIRmax × AIRmin)F2 intercross mice treated with urethane and phenotyped for AIR and lung tumor multiplicity. We mapped five loci on chromosomes 4, 6, 7, 11 and 13 linked to AIR (logarithm of odds (LOD)=3.56, 3.52, 15.74, 7.74 and 3.34, respectively) and two loci linked to lung tumor multiplicity, on chromosomes 6 and 18 (LOD=12.18 and 4.69, respectively). The known pulmonary adenoma susceptibility 1 (Pas1) locus on chromosome 6 was the only locus linked to both phenotypes, suggesting that alleles of this locus were differentially fixed during breeding and selection of AIR mice. These results represent a step toward understanding the link between inflammation and cancer.

Association study by genetic clustering detects multiple inflammatory response loci in non-inbred mice

We tested the possibility to map loci affecting the acute inflammatory response (AIR) in an (AIRmax AIRmin) F2 intercrossmouse population derived from non-inbred parents, by association analysis in the absence of pedigree information. Using 1064 autosomal single nucleotide polymorphisms (SNPs), we clustered the intercross population into 12 groups of genetically related individuals. Association analysis adjusted for genetic clusters allowed to identify two loci, inflammatory response modulator 1 (Irm1) on chromosome 7 previously detected by genetic linkage analysis in the F2 mice, and a new locus onchromosome 5 (Irm2), linked to the number of infiltrating cells in subcutaneous inflammatory exudates (Irm1: P»6.3 10 7; Irm2: P»8.2 10 5) and interleukin 1 beta (IL-1b) production (Irm1: P»1.9 10 16; Irm2: P»1.1 10 6). Use of a polygenic model based on additive effects of the rare alleles of 15 or 18 SNPs associated at suggestive genome-wide statistical threshold(Po3.4 10 3) with the number of infiltrating cells or IL-1b production, respectively, allowed prediction of the inflammatory response of progenitor AIR mice. Our findings suggest the usefulness of association analysis in combination with genetic clustering to map loci affecting complex phenotypes in non-inbred animal species.

Association study by genetic clustering detects multiple inflammatory response loci in non-inbred mice.

We tested the possibility to map loci affecting the acute inflammatory response (AIR) in an (AIRmax × AIRmin) F2 intercross mouse population derived from non-inbred parents, by association analysis in the absence of pedigree information. Using 1064 autosomal single nucleotide polymorphisms (SNPs), we clustered the intercross population into 12 groups of genetically related individuals. Association analysis adjusted for genetic clusters allowed to identify two loci, inflammatory response modulator 1 (Irm1) on chromosome 7 previously detected by genetic linkage analysis in the F2 mice, and a new locus on chromosome 5 (Irm2), linked to the number of infiltrating cells in subcutaneous inflammatory exudates (Irm1: P=6.3 × 10(-7); Irm2: P=8.2 × 10(-5)) and interleukin 1 beta (IL-1ß) production (Irm1: P=1.9 × 10(-16); Irm2: P=1.1 × 10(-6)). Use of a polygenic model based on additive effects of the rare alleles of 15 or 18 SNPs associated at suggestive genome-wide statistical threshold (P<3.4 × 10(-3)) with the number of infiltrating cells or IL-1ß production, respectively, allowed prediction of the inflammatory response of progenitor AIR mice. Our findings suggest the usefulness of association analysis in combination with genetic clustering to map loci affecting complex phenotypes in non-inbred animal species.

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.

Reduced humoral immunity in uremic mice genetically selected for high antibody response.

Biozzi's Selection IV-A mice, genetically selected for 25 generations for high and low antibody response to sheep red blood cells (SRBC), 2-3 months old, were made uremic by subtotal nephrectomy and characterized for antibody production against the selection antigen. T cell activity was evaluated in vitro by lymphocyte proliferation and interleukin 2 (IL 2) production in response to the super antigen staphylococcal enterotoxin B (SEB). Total and IgM antibody titers (log2) were similar in uremic and non-uremic low responder mice (total antibody: 4.0 +/- 0.6 vs 3.6 +/- 0.6; IgG: 3.0 +/- 0.7 vs 2.4 +/- 0.4), while uremic high responders presented with non-uremic animals (total antibody: 10.8 +/- 1.6 vs 13.0 +/- 0.2; IgG: 10.3 +/- 1.5 vs 11.7 +/- 0.3). T cell proliferation and IL 2 production were similar in uremic and non-uremic groups after SEB stimulation. The results indicate a genetic effect on sensitivity to humoral immune response modulation by uremic status, with deficient antibody production despite a normal T cell proliferative response to mitogen stimulation in short-duration renal failure in high responder mice.

Specific T-cell response correlates with resistance of genetic heterogeneous mouse populations to mouse hepatitis virus 3 infection.

In a recently published study [Vassão RC, Mello IGC, Pereira CA (1994) Arch Virol 137: 277-288] we have shown that the genetically selected high antibody responder mice (HIII) are susceptible and the low antibody responder counterparts (LIII) are resistant to death induced by experimental infection with mouse hepatitis virus 3 (MHV3). This report shows that the MHV3 titers in the peritoneal exudate (PE) of HIII mice, 3 days after infection, were more than 2 log greater than in the resistant LIII mice, the interferon gamma (IFN gamma) titers in the PE of both mouse populations being not significantly different. The treatment with monoclonal antibodies (mAb) against CD4+ or CD8+ T cells induced susceptibility among LIII mice. The depletion of CD4+ T-cell subset in LIII mice was evidenced by, and led to a significant reduction in, the IFN gamma synthesis in their PEs with a 100 fold increase in MHV3 titers. When lymph node cells (LNC) were harvested from MHV3-infected mice and stimulated "in vitro" with MHV3 inactivated by ultraviolet radiation (uv-MHV3), only LNC from LIII mice were capable of proliferating and synthesizing significant amounts of interleukin 2 (IL-2). The LNC proliferation and IL-2 synthesis were inhibited by treatment with mAbs against CD4 or CD8 molecules. The MHV3 infection induced in both lines of mice a profound depression of the mitogenic response of LNC to phytohemaglutinin (PHA). A correlation between the specific T-cell response and the resistance to MHV3 infection is discussed.

Potentiation of immune complex injury in rats by pretreatment with subnephrotoxic doses of guinea pig anti-glomerular basement membrane IgG1.

1. Female Wistar rats received a single subnephrotoxic dose of guinea pig anti-glomerular basement membrane (GBM) IgG1, 2.5 mg, followed by infusion of preformed immune complexes (BSA, 5.0 mg/rabbit anti-BSA, 6 mg), 10 X antigen excess. Control groups received guinea-pig IgG1 anti-GBM, or preformed immune complexes alone, or isotonic saline. Systemic reactions were observed clinically during the first 24 h, and 24 h urine was collected for the measurement of proteinuria and hematuria. 2. Blood was collected before and 2 h after the above treatment for the determination of complement (50% hemolytic assay), kininogen (isolated guinea pig assay of released bradykinin-like spasmogenic activity) and activated partial thromboplastin time (APTT). Kidney and lung tissue was examined by light microscopy, immunofluorescence and electron microscopy. 3. Rats treated with guinea pig anti-GBM IgG1 followed by BSA immune complex presented a severe systemic picture, with macroscopic hematuria (9/14), several deaths (8/14), slight proteinuria (24.6 +/- 5.2 mg/day), marked complement consumption (delta = 49.4 +/- 2.4 UCH50/ml), intravascular coagulation and severe diffuse interstitial pneumonia, obliteration of glomerular capillary walls by edema of endothelial cells, without deposition of immune complexes in kidneys or lungs. The control groups showed no signs of systemic reaction (isotonic saline alone) or slight dyspnea (guinea pig anti-GBM IgG1 or immune complexes alone), without proteinuria or macroscopic hematuria, and with foci of interstitial pneumonia. 4. Complement consumption was significant in rats receiving immune complexes alone (delta = 31.1 +/- 1.3 UCH50/ml) and even higher when associated with infusion of guinea pig anti-GBM IgG1 (delta = 49.3 +/- 2.4 UCH50/ml). APTT was significantly lengthened only for the group treated with guinea pig anti-GBM IgG1 plus immune complexes (delta = 18.5 +/- 1.9 s), with no alterations in the other groups. Kininogen consumption was demonstrable for all groups except the saline control and was more extensive in rats which received immune complexes alone or preceded by guinea pig IgG1. 5. These data show that previous infusion of a subnephrotoxic dose of guinea pig IgG1 anti-GBM aggravated the pathological effects of preformed immune complexes by promoting marked complement consumption and activation of the coagulation system, rather than by enhancing tissue deposition.

Infeccao estreptococica em cobaias (Cavia cobaya). / Streptococcal infection in guinea pigs (Cavia cobaya)

Dois surtos de adenite cervical em cobaias (Cavia cobaya) ocorreram de forma simultanea nos bioterios do Centro Panamericano de Febre Aftosa, Rio de Janeiro e na Secao de Imunologia do Instituto Biologico de Sao Paulo. Alem do comprometimento dos linfonodos cervicais, varias cobaias tambem apresentaram lesoes oculares com variavel grau de intensidade. De ambas epizootias, isolou-se o S. zooepidemicus, conforme constatado atraves de provas bioquimicas e sorologicas. A partir do agente isolado, foi possivel a reproducao da doenca. A histopatologia permitiu evidenciar processos inflamatorios, comprometendo diversas estruturas do globo ocular com tecido de granulacao, infiltracao linfo-histiocitaria e vasos de neoformacao. Medidas profilaticas e administracao diaria de quimioterapico, 5% (p/p) de sulfamilamida na racao, foram eficazes para o controle da enfermidade