Exacerbation of chronic inflammatory diseases by infectious agents: Fact or fiction?

Table 1 Pathogens associated with obesity

Pathogen	Effect	Mechanisms	Ref
CDV	Increased body weight in Swiss albino mice	Altered hypothalamic integrity; increased cytokine production, hyperinsulinemia and decreased leptin and neuropeptides	[15-17,21,22]
RAV-7	Stunting, anemia and increased visceral fat in white leghorn chickens	Decreased thyroxine, hyperlipidemia and hyperinsulinemia	[23,24]
BDV	Obesity with increased visceral fat in Lewis rats	Inflammatory lesions in hypothalamus, increased triglyceride and blood glucose	[35,36]
SMAM-1	Stunting and increased visceral fat in white leghorn chickens	Impaired liver function and lipogenesis and glucagon deficiency	[49,50]
Scrapie agent	Increased body weight and fat accumulation in mice	Altered brain function and reduced GLUT-1	[43,44]
Adenovirus	Increased body weight in chickens, mice, rats and monkeys; seropositive subjects were heavier than seronegative counterparts	Increased replication, differentiation and lipid accumulation of preadipocytes	[51-60]

CDV: Canine distemper virus; RAV-7: Rous-associated virus-7; BDV: Borna disease virus; Ref: Reference.

Table 2 Pathogens associated with increased chronic inflammatory diseases in humans

Pathogen	Effect	Mechanisms	Ref
H. pylori	Affected subjects showed increased insulin resistance	Increased concentrations of plasma glucose and lipids	[64-67]
C. pneumoniae	Increased metabolic syndrome, insulin resistance and cardiovascular disease	Increased production of proinflammatory and circulating cytokines	[68-72]
P. gingivalis	Adults with dental infections demonstrated higher chance of insulin resistance and diabetes	Increased oxidative stress, advanced glycation end-products and altered immune function	[86-90]
HCV	Infected patients showed increased chance to develop insulin resistance and diabetes	Increased production of TNF and IL-6	[92-95]
HIV	HIV patients showed higher insulin resistance (35%) compared to normal subjects (5%)	Impaired glucose tolerance and significant hyperinsulinaemia	[96,97]

H. pylori: Helicobacter pylori; C. pneumoniae: Chlamydia pneumoniae; P. gingivalis: Porphyromonas gingivalis; HCV: Hepatitis C virus; HIV: human immunodeficiency virus; Ref: Reference.