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Clinical and serologic manifestations of autoimmune disease in MRL-lpr/lpr mice lacking nitric oxide synthase type 2.

Gilkeson GS, Mudgett JS, Seldin MF, Ruiz P, Alexander AA, Misukonis MA, Pisetsky DS, Weinberg JB - J. Exp. Med. (1997)

Bottom Line: In previous studies, we showed that inhibiting NO production with the nonselective nitric oxide synthase (NOS) inhibitor NG-monomethyl-arginine reduced glomerulonephritis, arthritis, and vasculitis in MRL-lpr/lpr mice.MRL-lpr/lpr littermates homozygous for disrupted NOS2 (-/-), heterozygous for disrupted NOS2 (+/-), or wildtype (+/+) were derived for this study.There was no detectable NOS2 protein by immunoblot analysis of the spleen, liver, kidney, and peritoneal macrophages of the (-/-) animals, whereas that of (+/+) was high and (+/-) intermediate.

View Article: PubMed Central - PubMed

Affiliation: Ralph H. Johnson Veterans Affairs Medical Center, Medical University of South Carolina, Charleston 29425, USA.

ABSTRACT
Nitric oxide (NO) is an important mediator of the inflammatory response. MRL-lpr/lpr mice overexpress inducible nitric oxide synthase (NOS2) and overproduce NO in parallel with the development of an autoimmune syndrome with a variety of inflammatory manifestations. In previous studies, we showed that inhibiting NO production with the nonselective nitric oxide synthase (NOS) inhibitor NG-monomethyl-arginine reduced glomerulonephritis, arthritis, and vasculitis in MRL-lpr/lpr mice. To define further the role of NO and NOS2 in disease in MRL-lpr/lpr mice, mice with targeted disruption of NOS2 were produced by homologous recombination and bred to MRL-lpr/lpr mice to the N4 generation. MRL-lpr/lpr littermates homozygous for disrupted NOS2 (-/-), heterozygous for disrupted NOS2 (+/-), or wildtype (+/+) were derived for this study. Measures of NO production were markedly decreased in the MRL-lpr/lpr (-/-) mice compared with MRL-lpr/lpr (+/+) mice, with intermediate production by the MRL-lpr/lpr (+/-) mice. There was no detectable NOS2 protein by immunoblot analysis of the spleen, liver, kidney, and peritoneal macrophages of the (-/-) animals, whereas that of (+/+) was high and (+/-) intermediate. The (-/-) mice developed glomerular and synovial pathology similar to that of the (+/-) and (+/+) mice. However, (-/-) mice and (+/-) mice had significantly less vasculitis of medium-sized renal vessels than (+/+) mice. IgG rheumatoid factor levels were significantly lower in the (-/-) mice as compared with (+/+) mice, but levels of anti-DNA antibodies were comparable in all groups. Our findings show that NO derived from NOS2 has a variable impact on disease manifestations in MRL-lpr/lpr mice, suggesting heterogeneity in disease mechanisms.

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(A and B) Pathologic features of NOS2-modified MRL–lpr/lpr mice. 20-wk-old mice were examined. The bars show the mean and one standard deviation for the designated groups for renal and joint scores (A), and vessel scores (B).
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Figure 3: (A and B) Pathologic features of NOS2-modified MRL–lpr/lpr mice. 20-wk-old mice were examined. The bars show the mean and one standard deviation for the designated groups for renal and joint scores (A), and vessel scores (B).

Mentions: Based on the effect of in vivo administration of NG-monomethyl-l-arginine on renal disease and arthritis in MRL–lpr/lpr mice (7), we predicted that (−/−) mice would develop less renal disease and arthritis than mice of the other two groups. However, pathologic examination indicated that glomerulonephritis in the (−/−) mice was similar in severity to that of the other two groups. Proliferative glomerulonephritis was present in all mice regardless of NOS2 genotype, with overall glomerular scores similar between the groups (Figs. 3 A and 4 A). Crescentic glomerulonephritis and interstitial disease were present in a small number of mice in each group. 24-h urinary protein excretion at 20 wk of age was less in the (−/−) mice than in the other two groups (4.5 ± 2.8 [mean ± SD] mg/day for [+/+], 2.6 ± 3.0 for [+/−], and 1.9 ± 0.5 for [−/−]), but these were not statistically different. Synovitis was present in the majority of the mice with overall synovial scores similar in the three groups. Synovial hypertrophy, synovial inflammation, and erosive disease were present to a similar degree in the MRL–lpr/lpr mice regardless of NOS2 genotype (Figs. 3 A and 4 B).


Clinical and serologic manifestations of autoimmune disease in MRL-lpr/lpr mice lacking nitric oxide synthase type 2.

Gilkeson GS, Mudgett JS, Seldin MF, Ruiz P, Alexander AA, Misukonis MA, Pisetsky DS, Weinberg JB - J. Exp. Med. (1997)

(A and B) Pathologic features of NOS2-modified MRL–lpr/lpr mice. 20-wk-old mice were examined. The bars show the mean and one standard deviation for the designated groups for renal and joint scores (A), and vessel scores (B).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2199001&req=5

Figure 3: (A and B) Pathologic features of NOS2-modified MRL–lpr/lpr mice. 20-wk-old mice were examined. The bars show the mean and one standard deviation for the designated groups for renal and joint scores (A), and vessel scores (B).
Mentions: Based on the effect of in vivo administration of NG-monomethyl-l-arginine on renal disease and arthritis in MRL–lpr/lpr mice (7), we predicted that (−/−) mice would develop less renal disease and arthritis than mice of the other two groups. However, pathologic examination indicated that glomerulonephritis in the (−/−) mice was similar in severity to that of the other two groups. Proliferative glomerulonephritis was present in all mice regardless of NOS2 genotype, with overall glomerular scores similar between the groups (Figs. 3 A and 4 A). Crescentic glomerulonephritis and interstitial disease were present in a small number of mice in each group. 24-h urinary protein excretion at 20 wk of age was less in the (−/−) mice than in the other two groups (4.5 ± 2.8 [mean ± SD] mg/day for [+/+], 2.6 ± 3.0 for [+/−], and 1.9 ± 0.5 for [−/−]), but these were not statistically different. Synovitis was present in the majority of the mice with overall synovial scores similar in the three groups. Synovial hypertrophy, synovial inflammation, and erosive disease were present to a similar degree in the MRL–lpr/lpr mice regardless of NOS2 genotype (Figs. 3 A and 4 B).

Bottom Line: In previous studies, we showed that inhibiting NO production with the nonselective nitric oxide synthase (NOS) inhibitor NG-monomethyl-arginine reduced glomerulonephritis, arthritis, and vasculitis in MRL-lpr/lpr mice.MRL-lpr/lpr littermates homozygous for disrupted NOS2 (-/-), heterozygous for disrupted NOS2 (+/-), or wildtype (+/+) were derived for this study.There was no detectable NOS2 protein by immunoblot analysis of the spleen, liver, kidney, and peritoneal macrophages of the (-/-) animals, whereas that of (+/+) was high and (+/-) intermediate.

View Article: PubMed Central - PubMed

Affiliation: Ralph H. Johnson Veterans Affairs Medical Center, Medical University of South Carolina, Charleston 29425, USA.

ABSTRACT
Nitric oxide (NO) is an important mediator of the inflammatory response. MRL-lpr/lpr mice overexpress inducible nitric oxide synthase (NOS2) and overproduce NO in parallel with the development of an autoimmune syndrome with a variety of inflammatory manifestations. In previous studies, we showed that inhibiting NO production with the nonselective nitric oxide synthase (NOS) inhibitor NG-monomethyl-arginine reduced glomerulonephritis, arthritis, and vasculitis in MRL-lpr/lpr mice. To define further the role of NO and NOS2 in disease in MRL-lpr/lpr mice, mice with targeted disruption of NOS2 were produced by homologous recombination and bred to MRL-lpr/lpr mice to the N4 generation. MRL-lpr/lpr littermates homozygous for disrupted NOS2 (-/-), heterozygous for disrupted NOS2 (+/-), or wildtype (+/+) were derived for this study. Measures of NO production were markedly decreased in the MRL-lpr/lpr (-/-) mice compared with MRL-lpr/lpr (+/+) mice, with intermediate production by the MRL-lpr/lpr (+/-) mice. There was no detectable NOS2 protein by immunoblot analysis of the spleen, liver, kidney, and peritoneal macrophages of the (-/-) animals, whereas that of (+/+) was high and (+/-) intermediate. The (-/-) mice developed glomerular and synovial pathology similar to that of the (+/-) and (+/+) mice. However, (-/-) mice and (+/-) mice had significantly less vasculitis of medium-sized renal vessels than (+/+) mice. IgG rheumatoid factor levels were significantly lower in the (-/-) mice as compared with (+/+) mice, but levels of anti-DNA antibodies were comparable in all groups. Our findings show that NO derived from NOS2 has a variable impact on disease manifestations in MRL-lpr/lpr mice, suggesting heterogeneity in disease mechanisms.

Show MeSH
Related in: MedlinePlus