Effect of mycobacterial infection in the lupus-prone MRL/lpr mice: enhancement of life span of autoimmune mice, amelioration of kidney disease and transient decrease in host resistance.
We have used the MRL/lpr murine model of spontaneous lupus to investigate three questions in infection immunity: (1) does mycobacterial infection have any effect on the mortality of the autoimmunity-prone lpr mice?; (2) does the infection modify the progression of kidney disease of lpr lupus?; and (3) does the lpr gene change the resistance of mice to mycobacteria? Experimental infections were induced by intraperitoneal inoculation of 10(7) viable bacilli of Mycobacterium avium in 3 months old MRL/lpr mice and also in congeneic MRL/+ mice (lacking the lpr gene). MRL mice were sacrificed 1, 2.5 and 4 months after the M. avium injection. We found that infection caused lowering of urine protein concentration in lpr mice as compared with age-matched lpr controls. Mycobacteriosis also induced a marked decrease in the mortality of lpr animals, e.g. 85% of infected lpr mice reached the age of 7 months whereas only 10% of control lpr mice reached the same age. MRL/lpr mice showed, after 1 and 2.5 months of infection, higher mycobacterial loads than the congeneic non-lpr MRL mice; after 4 months of infection, however, differences in M. avium loads between the two groups of MRL mice became not statistically significant. We conclude that: (1) mycobacterial infection increases the life span of lpr mice; (2) the infection slows down the progression of kidney disease in the lupus-prone lpr animals; (3) the autoimmunity gene lpr is associated with a transient decrease in host resistance to mycobacteria.
Castro
A P
AP
Center for Experimental Cytology, Abel Salazar Institute for the Biomedical Sciences, University of Porto, Portugal.
Esaguy
N
N
Aguas
A P
AP
D000818:Animals; D001327:Autoimmune Diseases / Q000150:complications / Q000276:immunology* / Q000401:mortality; D005260:Female; D007113:Immunity, Innate / Q000502:physiology; D008181:Lupus Nephritis / Q000150:complications / Q000276:immunology* / Q000401:mortality; D051379:Mice; D008815:Mice, Inbred Strains; D009164:Mycobacterium Infections / Q000150:complications / Q000276:immunology*; D009162:Mycobacterium avium