Environmental factors associated with Crohn's disease in India-there's more to it than meets the eye

Role of STAT3 and PPAR-γ in pathogenesis of UC: Implications for therapeutic effect of curcumin

AIM: To investigate the role of signal transducer and activator of transcription 3 (STAT3) and peroxisome proliferator-activated receptor-γ (PPAR-γ) in the pathogenesis of ulcerative colitis (UC) in mice, and the effect of curcumin on STAT3 pathway, cyclooxygenase-2 (COX-2), and peroxisome proliferator-activated receptor γ (PPAR-γ) in UC.

METHODS: Sixty female BALB/c mice were randomly and equally divided into six groups: A (normal group), B (model group), C [dexamethasone intervention group, 1.5 mg/(kg•d)], L [low dose curcumin group, 25 mg/(kg•d)], M [medium dose curcumin group, 50 mg/(kg•d)], and H (high dose curcumin group, 100 mg/(kg•d)]. UC was induced in mice with dextran sodium sulfate. Disease activity index (DAI) scores were calculated in UC mice. HE staining was performed for observing colonic histological changes. PPAR-γ and STAT3 expression was detected by immunohistochemistry. The expression of COX-2 was detected by ELISA, the expression of p-STAT3 was detected by Western blot, and the expression of STAT3 mRNA was detected by RT-PCR.

RESULTS: Mice in group B showed symptoms and histological changes consistent with UC standards. DAI and histological scores in group B were higher than those in group A, but compared with group B, DAI and histological scores in groups C, L, M and H showed varying degrees of decrease. Immunohistochemical results showed that the expression of PPAR-γ in mouse colon in group B was lower than that in group A (23.15 ± 2.33 vs 42.07 ± 3.82, P < 0.01). The expression of STAT3 in mouse colon in group B was significantly higher than that in groups A, C, L, M and H (66.36 ± 6.08 vs 28.25 ± 2.84, 29.84 ± 3.32, 45.26 ± 5.42, 29.02 ± 3.28, 21.22 ± 3.30, P < 0.01). The expression of COX-2 in mouse colon in groups C, L, M and H was lower than that in group B (P < 0.01). The expression of p-STAT3 in mouse colon in group B was significantly higher than that in group A, but lower than that in groups C, L, M and H (P < 0.05). The expression of STAT3 mRNA in mouse colon in group B was significantly higher than that in group A, but lower than that in groups C, L, M and H (P < 0.05).

CONCLUSION: STAT3 and PPAR-γ may participate in the pathogenesis of UC. The mechanism of curcumin for treating UC may be through increasing the expression of PPAR-γ, inhibiting STAT3 signaling pathway, reducing the release of COX-2, decreasing neutrophil infiltration and thus attenuating colonic mucosa damage.

A multimodal Darwinian strategy for alleviating the atherosclerosis pandemic

The conflict between our 'primitive' genes and 'modern' lifestyle probably lies at the root of several disorders that afflict modern man. Atherosclerosis, which is relatively unknown among contemporary hunter-gatherer populations, has reached pandemic proportions in recent times. Being an evolutionary problem with several inter-related pathologies, current therapeutic strategy for treating atherosclerosis has inherent limitations. Reviewing evolution-linked risk factors suggests that there are four aspects to the etiology of atherosclerosis namely, decreased intestinal parasitism, oversensitivity of evolutionarily redundant mast cells, chronic underactivation of AMPK (cellular energy sensor) and a deficiency of vitamin D. A combination of these four causes appear to have precipitated the atherosclerosis pandemic in modern times. Man and worms co-existed symbiotically in the past. Massive de-worming campaigns could have disrupted this symbiosis, increasing nutritional availability to man (pro-obesity) at the cost of decreased immunotolerance (pro-atherogenicity). A reduction in helminth-induced chronic TH2 activation could also have enhanced TH1 polarization, eventually disrupting the reciprocal regulation of TH1/TH2 balance and resulting in atherosclerosis. The riddance of helminth infestations may have rendered mast cells immunologically redundant, making them oversensitive to inflammatory stimuli, thereby playing a pro-atherogenic role. AMPK activation exerts pleiotropic anti-atherogenic effects, such as suppression of fatty acid, cholesterol, protein synthesis, reduction of vascular smooth muscle proliferation, etc. As energy deficit is the chief stimulus for AMPK activation, the over-nourished modern man appears to be suffering from chronic underactivation of AMPK, legitimising the unrivalled supremacy of metformin, the oldest prescribed antidiabetic drug. The fact that humans evolved in the sunny tropics suggests that humans are selected for high vitamin D levels. Vitamin D deficiency is now linked to several conditions including increased risk of CV disorders, diabetes, etc. The manifold decrease in vitamin D levels in modern man justifies a need for supplementation. We therefore hypothesize that a judicious combination of mast cell stabilization, AMPK activation, vitamin D supplementation, and moderation in hygiene practices could be an evolution-based multimodal strategy for both preventing and mitigating the pandemic of atherosclerosis.