| dc.description.abstract | A person’s social network size and quality of life can affect the body at three levels:
behavioural, psychological and physiological. A socially isolated person is more likely
to have a poor diet, suffer from depression and have increased blood pressure, all of
which are risk factors for chronic inflammatory diseases. This thesis aimed to understand
how social isolation affects the immune system in the acute inflammatory setting, sepsis,
and in the chronic inflammatory setting, atherosclerosis.
CD-1 mice subjected to 2 weeks of social isolation had increased food intake without
increased weight gain, a finding that was accompanied by an increased number of smaller
adipocytes suggesting socially isolated mice have increased thermogenesis to maintain
body temperature. Social isolation profoundly altered the microbiota to one that is proinflammatory.
Microarray analysis of whole blood revealed a unique transcriptional
fingerprint for social isolation.
After 2 weeks of social isolation, mice were given E.coli induced sepsis and found to
have enhanced bacterial clearance. Toll-like receptor signalling pathways in peritoneal
macrophages revealed that genes involved in fighting bacterial infections were
upregulated. Social isolation was neither beneficial nor detrimental during viral sepsis.
ApoE-/- mice underwent social isolation for a 4-week period. Mice subjected to social
isolation maintained a consistent calorie intake both on the Western diet and standard
diet whilst socially housed mice increased their calorie intake on the Western diet
probably as a result of leptin resistance. Social isolation did not increase atherosclerotic
burden but increased necrosis in the atherosclerotic plaque suggesting that social
isolation might increase risk of plaque rupture.
This thesis demonstrated for the first time that just 2-4 weeks of social isolation causes
profound immunological and metabolic changes in the body which might account in part
for the increased risk of chronic inflammatory diseases seen in socially isolated people. | en_US |
