On the Relationship between Sialomucin and Sulfomucin Expression and Hydrogenotrophic Microbes in the Human Colonic Mucosa

Abstract

The colonic mucus layer is comprised primarily of acidomucins, which provide viscous properties and can be broadly classified into sialomucins or sulfomucins based on the presence of terminating sialic acid or sulfate groups. Differences in acidomucin chemotypes have been observed in diseases such as colorectal cancer and inflammatory bowel disease, and variation in sialo- and sulfomucin content may influence microbial colonization. For example, sulfate derived from sulfomucin degradation may promote the colonization of sulfate-reducing bacteria (SRB), which through sulfate respiration generate the genotoxic gas hydrogen sulfide. Here, paired biopsies from right colon, left colon, and rectum of 20 subjects undergoing routine screening colonoscopies were collected to enable parallel histochemical and microbiological studies. Goblet cell sialo- and sulfomucins in each biopsy were distinguished histochemically and quantified. Quantitative PCR and multivariate analyses were used to examine the abundance of hydrogenotrophic microbial groups and SRB genera relative to acidomucin profiles. Regional variation was observed in sialomucins and sulfomucins with the greatest abundance of each found in the rectum. Mucin composition did not appear to influence the abundance of SRB or other hydrogenotrophic microbiota but correlated with the composition of different SRB genera. A higher sulfomucin proportion correlated with higher quantities of Desulfobacter, Desulfobulbus and Desulfotomaculum, relative to the predominant Desulfovibrio genus. Thus, acidomucin composition may influence bacterial sulfate respiration in the human colon, which may in turn impact mucosal homeostasis. These results stress the need to consider mucus characteristics in the context of studies of the microbiome that target intestinal diseases.

Mucin expression patterns in histological grades of colonic cancers in a Ghanaian population

“…In order to achieve this, 25 colonic tissues consisting of 3 normal and 22 different graded colonic cancers, were histocemically stained to assess the types of mucins. Following histochemical staining (diastase-AB/PAS), it was observed that the normal colonic tissue demonstrated predominance of acidic mucin (80%) and scanty neutral mucin (20%), confirming what have been made already [15,20] that acidic mucin is copiously present in the colon for the primary role of viscosity. A striking pattern, contrary to the amount of mucins in normal colon, was observed in low graded well-differentiated adenocarcinomas of the colon-a decrease in acid mucin (73.7%) and an increase in the neutral mucin expression (26.3%) as compared to the normal colon mucin variant expression (Table 2).…”

The distribution of mucous secreting cells in the gastrointestinal tracts of three small rodents from Saudi Arabia: Acomys dimidiatus , Meriones rex and Meriones libycus

“…Sulfomucins are a crucial source of sulfate for sulfate-reducing bacteria and play a prominent protective role by increasing mucus viscosity (Croix et al, 2011). It is suggested that sulfomucins are able to reduce the rate at which microflora degrade mucins (Robertson and Wright, 1997) as the high sulfate content of sulfomucins decrease its susceptibility to bacterial glycosidases, limiting the rate and extent of mucin degradation (Hino et al, 2012).…”

An Adhesin-Like Protein, Lam29, fromLactobacillus mucosaeME-340 Binds to Histone H3 and Blood Group Antigens in Human Colonic Mucus

“…24) The mucosal surfaces of the human intestine contain negatively charged molecules, including sialic acid and sulfate groups. 25,26) Hence, it was suggested that extracellular histones released from the cells by apoptosis bind to the negatively charged surfaces of adjacent viable cells. 27) We detected histone H3 in human colonic mucus, indicating highly basic histones other than histone H1 would also be released into the lumen from intestinal epithelial cells and localized on the mucosal surfaces by electrostatic interaction.…”