A proteomic approach to investigate enhanced responsiveness in rechallenged adult rats prenatally exposed to lindane.

Proteomic analysis was carried out in substantia nigra (SNi) and hippocampus (Hi) isolated from rat offspring born to mothers exposed to lindane (orally; 0.25 mg/kg) from gestation day 5 (GD5) to GD 21 and subsequently rechallenged (orally; 2.5 mg/kg X 21 days) at adulthood (12 weeks). 2D gel electrophoresis revealed no significant differences in the expression of proteins in brain regions isolated from prenatally exposed offspring at adulthood. Significantly greater magnitude of alterations was observed in the expression of proteins related to mitochondrial and energy metabolism, ubiquitin-proteasome pathway, structural and axonal growth leading to increased oxidative stress in Hi and SNi isolated from rechallenged offspring when compared to control offspring treated postnatally with lindane. Western blotting and DNA laddering showed a greater magnitude of increase in apoptosis in the Hi and SNi of rechallenged offspring. Ultrastructural analysis demonstrated disrupted mitochondrial integrity, synaptic disruption and necrotic structures in the brain region of rechallenged offspring. Neurobehavioral studies also demonstrated a greater magnitude of alterations in cognitive and motor functions in rechallenged rats. The data suggest that prenatal exposure of lindane induces persistent molecular changes in the nervous system of offspring which are unmasked leading to neurodegeneration following rechallenge at adulthood.

Overexpression of cerebral cytochrome P450s in prenatally exposed offspring modify the toxicity of lindane in rechallenged offspring.

Prenatal exposure to low doses of lindane, an organochlorine insecticide used in public health and agriculture, induced a persistent increase in the expression of cerebral cytochrome P450s (CYPs) in rat offspring and modify the adult response to a later exposure of xenobiotics. To understand the mechanism involved in the modification of adult response, rat offspring exposed prenatally to lindane (p.o.; 0.25 mg/kg b.wt. from gestation day 5-21) were rechallenged with lindane (p.o.; 5 mg/kg X 5 days) postnatally at 9- or 18- or 27 weeks. The greater magnitude of increase in the expression of cerebral CYPs in rechallenged offspring and decline in the magnitude of increase in CYPs with increasing age correlated with the amount of lindane accumulating in the brain. Significant alterations in the circulatory levels of hormones in the rechallenged offspring suggest that these alterations may partly account for the persistence in the increase in the cerebral CYPs during development. Epigenetic data further revealed alterations in histone H3 acetylation and DNA methylation in promoter regions of cerebral CYPs isolated from rechallenged offspring at 9- or 18- or 27 weeks. Bisulphite sequencing revealing critical CpG methylation changes in the promoter regions in rechallenged offspring at 9 weeks demonstrated imprinting of the cerebral CYPs. Further, a greater magnitude of increase in apoptosis in the brain of rechallenged offspring has suggested that enhanced responsiveness of cerebral CYPs, which may result due to alterations in circulatory hormones, increased accumulation of lindane in the brain and epigenetic regulation of CYPs, is of toxicological relevance.

Imprinting of cerebral cytochrome P450s in offsprings prenatally exposed to cypermethrin augments toxicity on rechallenge.

Epigenetic studies were carried in the rat offsprings, born to dams treated with cypermethrin (orally; 5.0 mg/kg) from gestation day (GD) 5 to 21 and rechallenged with cypermethrin (orally; 10 mg/kg for 6 days), at adulthood (12 weeks) to understand the mechanism underlying the overexpression of cerebral cytochrome P450s (CYPs) in exposed offsprings. The data revealed alterations in histone H3 acetylation and DNA methylation in promoter regions of CYP1A- and 2B- isoenzymes in the brain isolated from rechallenged animals. Further, bisulphite sequencing revealed critical CpG methylation changes in BARBIE BOX (Barbiturate response element) and BTE (Basal transcription element) in promoter of CYP2B1 in the brain isolated from rechallenged animals. Western blotting and DNA laddering/fragmentation studies revealed a greater magnitude of increase in the signalling pathways associated with apoptosis in the rechallenged animals. The data have indicated that overexpression of cerebral CYPs could be due to the imprinting of CYPs. Further, increased apoptosis observed in the rechallenged offsprings has suggested that these epigenetic changes in CYPs may predispose the prenatally exposed offsprings to the neurotoxic effects of other centrally acting drugs and chemicals when subsequently rechallenged later at life.

Cytokine gene polymorphisms are associated with risk of urinary bladder cancer and recurrence after BCG immunotherapy.

The association of interleukin-1beta (IL-1B) -511C > T and IL-1 receptor antagonist (IL-1RN) VNTR, transforming growth factor-beta (TGF-B1) +28C > T and interferon-gamma (IFN-G) + 874T>A polymorphisms with bladder cancer (CaB) susceptibility and risk of recurrence in Bacillus Calmette-Guérin (BCG)-treated patients was analyzed in 287 controls and 213 CaB patients (73 BCG treated). Increased risk was observed with the IL-1RN*2 allele (odds ratio (OR) 5.01) and the IFN-G +874 A allele (OR 1.78). TGF-B TT and IFN-G +874 A carriers were associated with reduced (hazard ratio (HR) 0.37) and enhanced (HR 2.24) risk of recurrence after BCG immunotherapy, respectively. The study suggests that cytokine gene variants may modulate CaB susceptibility and risk of recurrence after BCG immunotherapy.