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Th2 immune responses and alternatively activated macrophages (AAMacs) in helminth infection in aged mice
Yasuhiro Sugawara1, Noritsugu Azuma, Sachi Onodera
1School of Food, Agricultural and Environmental Sciences, Miyagi University, Miyagi, Japan.
Abstract:
This study aims to understand Th2 immune responses and alternative macrophage activation against nematode parasites in aged mice. Eighteen-month (18 M) and three-month (3 M) old C3H/HeN mice were inoculated with Heligmosomoides polygyrus (Hp) larvae. Real-time PCR analysis indicated that interleukin (IL)-4 and IL-13 gene expression was elevated in both groups after infection, but the expression level was significantly low in 18 M mice. Macrophage phenotype was monitored by measuring arginase-1 gene expression and immunofluorescence staining in small intestine, showing a decrease in the number of alternatively activated macrophages (AAMacs) around worm cysts in 18 M mice. These results suggest that the Th2 immune response in aged mice against a nematode parasite was not sufficiently induced to promote AAMacs.
Insights
Aging impairs immune responses to nematode parasites. Aged mice showed reduced Th2 immune responses and fewer alternatively activated macrophages (AAMacs), indicating a weaker defense against parasitic infections.
Area of Science:
- Immunology
- Parasitology
- Gerontology
Background:
- Aging is associated with altered immune function, potentially impacting host defense against pathogens.
- Helminth infections are common and elicit Th2 immune responses, involving alternatively activated macrophages (AAMacs).
Purpose of the Study:
- To investigate Th2 immune responses and alternative macrophage activation in aged mice infected with the nematode parasite Heligmosomoides polygyrus (Hp).
Main Methods:
- Comparison of immune responses in 18-month-old (aged) and 3-month-old (young) C3H/HeN mice infected with Hp larvae.
- Quantitative real-time PCR to measure interleukin (IL)-4 and IL-13 gene expression.
- Arginase-1 gene expression and immunofluorescence staining to assess macrophage phenotype in the small intestine.
Main Results:
- Both young and aged mice showed elevated IL-4 and IL-13 gene expression post-infection, but levels were significantly lower in aged mice.
- Aged mice exhibited a reduced number of alternatively activated macrophages (AAMacs) around worm cysts compared to young mice.
- These findings suggest an impaired ability to induce AAMacs in aged mice during nematode infection.
Conclusions:
- The Th2 immune response against nematode parasites is diminished in aged mice.
- Aging compromises the induction of alternatively activated macrophages, potentially leading to reduced parasite clearance.
