A Comparative Study on Rat Intestinal Epithelial Cells and Resident Gut Bacteria: (I) Effect of Hexavalent Chromium

Abstract

Toxicants including heavy metals reaching the intestine following ingestion through food and water primarily interact with an ecosystem of eukaryotic and prokaryotic cells. Gut bacteria having a dynamic interrelationship with intestinal epithelial cells are known to play important and specific metabolic, trophic, and protective functions. The present study was undertaken to compare the effects of hexavalent chromium on rat intestinal epithelial cells and the resident gut bacteria following in vitro and in vivo exposures. The survival rate and viability pattern of two types of cells were comparable. Under in vitro conditions, the gut bacteria were quick to reduce Cr (VI) in early time periods, while, at 30 h time, both types of cells showed similar capacity for the reduction of Cr (VI). Chromium intoxication (10 ppm of Cr (VI) in drinking water for 10 weeks) caused significant decrease in membrane alkaline phosphatase and Ca(2 +)-Mg(2 +)-ATPase activities of intestinal epithelial cells as well as of three gut bacteria viz. Escherichia coli, Pseudomonas sp, and Lactobacillus sp. Major structural membrane constituents like carbohydrates and phospholipids also showed significant decline in both types of cells. These findings indicate that 10 ppm and higher Cr concentrations may cause toxic insult, resulting in impaired intestinal functional efficacy. It also implies that the gut bacteria can be used at least for preliminary screening of heavy metals gastrointestinal toxicity.

The colony count of <i>Escherichia coli</i> in the stool of palmar arsenical keratosis following probiotics supplementation

“…Growth and multiplication of bacteria is an important parameter to study the response to toxic insults as it reflects directly to the viability of the bacterial population. The study conducted by Upreti et al (2006) also revealed a concentration dependent inhibition on in vitro exposure of gut flora to arsenic. Here this study showed that in chronic exposure to arsenic, the colony count of E. coli was decreased in arsenic exposed controls and severely decreased in arsenicosis patients in relation to healthy volunteers.…”

“…Though a few studies have been carried out to see the interactions between gut flora and arsenic (Upreti et al, 2006), still then researchers findings showed that hepatic methylation of inorganic arsenic produce MMA III and DMA III which are considered to be more toxic (Stylbo et al, 2002;Vahter, 2002;Gamble et al, 2005). On the other hand, gut flora produce MMA V and DMA V (Bently and Chasteen, 2002) which are relatively non-toxic and finally TMA III in gaseous form (Qin et al, 2006) whose volatilization lowers arsenic concentration in the body.…”

“…There were only two studies showing the effect of arsenic on gut flora. Choudhry et al, (2009) conducted an in vivo study in rat where as Upreti et al, (2006) conducted an in vitro study on rat stool. Both studies showed inhibitory effect of arsenic on gut flora.…”

“…On the other hand, gut flora produce MMA V and DMA V (Bently and Chasteen, 2002) which are relatively non-toxic and finally TMA III in gaseous form (Qin et al, 2006) whose volatilization lowers arsenic concentration in the body. Moreover, some bacteria possess the ability to enzymatically oxidize arsenite to less toxic arsenate (Upreti et al, 2006).…”

Inhibitory effect of arsenic on aerobic gut flora in rat

“…Ingested arsenic must undergo detoxification, in order that it is removed from the body, a process brought about by the liver, gut flora also plays a role in arsenic detoxification 8 . Although little work have been carried out to see the interaction between gut flora and arsenic 9 . Recent data suggest that hepatic methylation of arsenic leads to the formation of DMA-III and MMA-III which increases toxicity 10 , so more and more stress is being given on bacterial detoxification of arsenic which is considered to be non-toxic 11 .…”