Vitamin D and COVID-19-Revisited.

Vitamin D, when activated to 1,25-dihydroxyvitamin D, is a steroid hormone that induces responses in several hundred genes, including many involved in immune responses to infection. Without supplementation, people living in temperate zones commonly become deficient in the precursor form of vitamin D, 25-hydroxyvitamin D, during winter, as do people who receive less sunlight exposure or those with darker skin pigmentation. Studies performed pre-COVID-19 have shown significant but modest reduction in upper respiratory infections in people receiving regular daily vitamin D supplementation. Vitamin D deficiency, like the risk of severe COVID-19, is linked with darker skin colour and also with obesity. Greater risk from COVID-19 has been associated with reduced ultraviolet exposure. Various studies have examined serum 25-hydroxyvitamin D levels, either historical or current, in patients with COVID-19. The results of these studies have varied but the majority have shown an association between vitamin D deficiency and increased risk of COVID-19 illness or severity. Interventional studies of vitamin D supplementation have so far been inconclusive. Trial protocols commonly allow control groups to receive low-dose supplementation that may be adequate for many. The effects of vitamin D supplementation on disease severity in patients with existing COVID-19 are further complicated by the frequent use of large bolus dose vitamin D to achieve rapid effects, even though this approach has been shown to be ineffective in other settings. As the pandemic passes into its third year, a substantial role of vitamin D deficiency in determining the risk from COVID-19 remains possible but unproven.

Appearance of peanut agglutinin in the blood circulation after peanut ingestion promotes endothelial secretion of metastasis-promoting cytokines.

Peanut agglutinin (PNA) is a carbohydrate-binding protein in peanuts that accounts for ~0.15% peanut weight. PNA is highly resistant to cooking and digestion and is rapidly detectable in the blood after peanut consumption. Our previous studies have shown that circulating PNA mimics the actions of endogenous galactoside-binding protein galectin-3 by interaction with tumour cell-associated MUC1 and promotes circulating tumour cell metastatic spreading. The present study shows that circulating PNA interacts with micro- as well as macro-vascular endothelial cells and induces endothelial secretion of cytokines MCP-1 (CCL2) and IL-6 in vitro and in vivo. The increased secretion of these cytokines autocrinely/paracrinely enhances the expression of endothelial cell surface adhesion molecules including integrins, VCAM and selectin, leading to increased tumour cell-endothelial adhesion and endothelial tubule formation. Binding of PNA to endothelial surface MCAM (CD146), via N-linked glycans, and subsequent activation of PI3K-AKT-PREAS40 signalling is here shown responsible for PNA-induced secretion of MCP-1 and IL-6 by vascular endothelium. Thus, in addition to its influence on promoting tumour cell spreading by interaction with tumour cell-associated MUC1, circulating PNA might also influence metastasis by enhancing the secretion of metastasis-promoting MCP-1 and IL-6 from the vascular endothelium.

Randomized Trial of Ciprofloxacin Doxycycline and Hydroxychloroquine Versus Budesonide in Active Crohn's Disease.

BACKGROUND: Increased mucosa-associated E. coli are present in Crohn's disease, but their role in pathogenesis is uncertain. AIMS: To assess efficacy and safety of an antibiotic/hydroxychloroquine combination effective against E. coli inside macrophages. METHODS: Adults with moderately active disease (CDAI > 220-450 plus C reactive protein ≥ 5 mg/l and/or fecal calprotectin > 250 µg/g) were randomized to receive (open-label) oral budesonide (Entocort CR 9 mg/day 8 weeks, 6 mg/day 2 weeks, 3 mg/day 2 weeks) or oral ciprofloxacin 500 mg bd, doxycycline 100 mg bd, hydroxychloroquine 200 mg tds for 4 weeks, followed by doxycycline 100 mg bd and hydroxychloroquine 200 mg tds for 20 weeks. Primary endpoints were remission (CDAI ≤ 150) at 10 weeks, remission maintained to 24 weeks, and remission maintained to 52 weeks. Patients not responding (CDAI fall by > 70) by 10 weeks were invited to crossover onto the alternative therapy. RESULTS: Fifty-nine patients were recruited across 8 sites. Including crossover, 39 patients received antibiotics/hydroxychloroquine and 39 received budesonide. At 10 weeks, 24 weeks, and 52 weeks on initial therapy, only 2/27, 2/27, and 1/27 were in remission on antibiotics/hydroxychloroquine compared with 8/32, 1/32, and 1/32 on budesonide (P = 0.092 at 10 weeks). Withdrawals by 10 weeks due to adverse events were seen in 15 receiving antibiotics/hydroxychloroquine and 6 budesonide. Results including crossover were more promising with 9/24 patients receiving antibiotics/hydroxychloroquine per protocol in remission by 24 weeks. No correlation was seen between response to antibiotics/hydroxychloroquine and ASCA/OmpC antibody status or disease location. CONCLUSION: Overall results with this antibiotic/hydroxychloroquine combination were unimpressive, but long-term remission is seen in some patients and justifies further study.

Dietary Guidance From the International Organization for the Study of Inflammatory Bowel Diseases.

Recent evidence points to a plausible role of diet and the microbiome in the pathogenesis of both Crohn's disease (CD) and Ulcerative Colitis (UC). Dietary therapies based on exclusion of table foods and replacement with nutritional formulas and/or a combination of nutritional formulas and specific table foods may induce remission in CD. In UC, specific dietary components have also been associated with flare of disease. While evidence of varying quality has identified potential harmful or beneficial dietary components, physicians and patients at the present time do not have guidance as to which foods are safe, may be protective or deleterious for these diseases. The current document has been compiled by the nutrition cluster of the International Organization for the Study of Inflammatory Bowel Diseases (IOIBD) based on the best current evidence to provide expert opinion regarding specific dietary components, food groups and food additives that may be prudent to increase or decrease in the diet of patients with inflammatory bowel diseases to control and prevent relapse of inflammatory bowel diseases.

Ingested asbestos in filtered beer, in addition to occupational exposure, as a causative factor in oesophageal adenocarcinoma.

Oesophageal adenocarcinoma has become much more common over the past 50 years, particularly in Britain, with an unexplained male to female ratio of > 4:1. Given the use of asbestos filtration in commercial brewing and reports of its unregulated use in British public houses in the 1970's to clear draught beer "slops", we have assessed the hypothesis that ingested asbestos could be a causative factor for this increased incidence. Importantly, occupational asbestos exposure increases the risk of adenocarcinoma but not squamous cell carcinoma of the oesophagus. The presence of asbestos fibres was consistently reported in filtered beverages including beers in the 1970s and asbestos bodies have been found in gastrointestinal tissue, particularly oesophageal tissue, at autopsy. There is no reported association between the intake of alcohol and oesophageal adenocarcinoma but studies would mostly have missed exposure from draught beer before 1980. Oesophageal adenocarcinoma has some molecular similarities to pleural mesothelioma, a condition that is largely due to inhalation of asbestos fibres, including predominant loss of tumour suppressor genes rather than an increase of classical oncogenic drivers. Trends in incidence of oesophageal adenocarcinoma and mesothelioma are similar, rising rapidly over the past 50 years but now plateauing. Asbestos ingestion, either from beer consumed before around 1980, or from occupational exposure, seems a plausible causative factor for oesophageal adenocarcinoma. If this is indeed the case, its incidence should fall back to a low baseline by around 2050.

Galectin-3 interacts with the cell-surface glycoprotein CD146 (MCAM, MUC18) and induces secretion of metastasis-promoting cytokines from vascular endothelial cells.

The galactoside-binding protein galectin-3 is increasingly recognized as an important player in cancer development, progression, and metastasis via its interactions with various galactoside-terminated glycans. We have shown previously that circulating galectin-3, which is increased up to 30-fold in cancer patients, promotes blood-borne metastasis in an animal cancer model. This effect is partly attributable to the interaction of galectin-3 with unknown receptor(s) on vascular endothelial cells and causes endothelial secretion of several metastasis-promoting cytokines. Here we sought to identify the galectin-3-binding molecule(s) on the endothelial cell surface responsible for the galectin-3-mediated cytokine secretion. Using two different galectin-3 affinity purification processes, we extracted four cell membrane glycoproteins, CD146/melanoma cell adhesion molecule (MCAM)/MUC18, CD31/platelet endothelial cell adhesion molecule-1 (PECAM-1), CD144/VE-cadherin, and CD106/Endoglin, from vascular endothelial cells. CD146 was the major galectin-3-binding ligand and strongly co-localized with galectin-3 on endothelial cell surfaces treated with exogenous galectin-3. Moreover, galectin-3 bound to N-linked glycans on CD146 and induced CD146 dimerization and subsequent activation of AKT signaling. siRNA-mediated suppression of CD146 expression completely abolished the galectin-3-induced secretion of IL-6 and G-CSF cytokines from the endothelial cells. Thus, CD146/MCAM is the functional galectin-3-binding ligand on endothelial cell surfaces responsible for galectin-3-induced secretion of metastasis-promoting cytokines. We conclude that CD146/MCAM interactions with circulating galectin-3 may have an important influence on cancer progression and metastasis.

Recent advances in clinical practice: a systematic review of isolated colonic Crohn's disease: the third IBD?

The genetics of isolated colonic Crohn's disease place it approximately midway between Crohn's disease with small intestinal involvement and UC, making a case for considering it as a separate condition. We have therefore systematically reviewed its epidemiology, pathophysiology and treatment. Key findings include a higher incidence in females (65%) and older average age at presentation than Crohn's disease at other sites, a mucosa-associated microbiota between that found in ileal Crohn's disease and UC, no response to mesalazine, but possibly better response to antitumour necrosis factor than Crohn's disease at other sites. Diagnostic distinction from UC is often difficult and also needs to exclude other conditions including ischaemic colitis, segmental colitis associated with diverticular disease and tuberculosis. Future studies, particularly clinical trials, but also historical cohorts, should assess isolated colonic Crohn's disease separately.

Colonic mucosa-associated diffusely adherent afaC+ Escherichia coli expressing lpfA and pks are increased in inflammatory bowel disease and colon cancer.

OBJECTIVE: Colonic mucosa-associated Escherichia coli are increased in Crohn's disease (CD) and colorectal cancer (CRC). They variously haemagglutinate, invade epithelial cell lines, replicate within macrophages, translocate across M (microfold) cells and damage DNA. We investigated genes responsible for these effects and their co-association in colonic mucosal isolates. DESIGN: A fosmid library yielding 968 clones was prepared in E coli EPI300-T1 using DNA from a haemagglutinating CRC isolate, and resulting haemagglutinating clones were 454-pyrosequenced. PCR screening was performed on 281 colonic E coli isolates from inflammatory bowel disease (IBD) (35 patients), CRC (21) and controls (24; sporadic polyps or irritable bowel syndrome). RESULTS: 454-Pyrosequencing of fosmids from the haemagglutinating clones (n=8) identified the afimbrial adhesin afa-1 operon. Transfection of afa-1 into E coli K-12 predictably conferred diffuse adherence plus invasion of HEp-2 and I-407 epithelial cells, and upregulation of vascular endothelial growth factor. E coli expressing afaC were common in CRC (14/21, p=0.0009) and CD (9/14, p=0.005) but not ulcerative colitis (UC; 8/21) compared with controls (4/24). E coli expressing both afaC and lpfA (relevant to M-cell translocation) were common in CD (8/14, p=0.0019) and CRC (14/21, p=0.0001), but not UC (6/21) compared with controls (2/24). E coli expressing both afaC and pks (genotoxic) were common in CRC (11/21, p=0.0015) and UC (8/21, p=0.022), but not CD (4/14) compared with controls (2/24). All isolates expressed dsbA and htrA relevant to intra-macrophage replication, and 242/281 expressed fimH encoding type-1 fimbrial adhesin. CONCLUSIONS: IBD and CRC commonly have colonic mucosal E coli that express genes that confer properties relevant to pathogenesis including M-cell translocation, angiogenesis and genotoxicity.

Peanut agglutinin appearance in the blood circulation after peanut ingestion mimics the action of endogenous galectin-3 to promote metastasis by interaction with cancer-associated MUC1.

Peanut agglutinin (PNA), which accounts for ~0.15% of the weight of the common peanut, is a carbohydrate-binding protein that binds the oncofoetal Thomsen-Friedenreich (TF) disaccharide (galactoseß1,3N-acetylgalactosamineα-) that is overexpressed by ~90% of human cancers. Previous studies have shown that PNA is highly resistant to cooking and digestion and rapidly enters the human blood circulation after peanut ingestion. This study investigates the hypothesis that PNA appearance in the circulation after peanut ingestion may mimic the actions of endogenous TF-binding human galectin-3 in metastasis promotion. It shows that PNA at concentrations similar to those found in blood circulation after peanut ingestion increases cancer cell heterotypic adhesion to the blood vascular endothelium and enhances the formation of tumour cell homotypic aggregates, two important steps in the metastasis cascade, and enhances metastasis in a mouse metastasis model. These effects of PNA are shown to result from its interaction with the cancer-associated TF disaccharide on the transmembrane mucin protein MUC1, causing MUC1 cell surface polarization that reveals underlying cell surface adhesion molecules. Thus, PNA appearance in the blood circulation after peanut ingestion mimics the actions of endogenous galectin-3 and promotes cancer cell metastatic spread by interaction with cancer-associated TF/MUC1. As metastasis accounts for the majority of cancer-associated fatality, regular consumption of peanuts by cancer patients would therefore be expected to have an adverse effect on cancer survival.

Mucosal barrier, bacteria and inflammatory bowel disease: possibilities for therapy.

The mucosal barrier has three major components, the mucus layer, the epithelial glycocalyx and the surface epithelium itself, whose integrity largely depends on tight junction function. In health, there is relatively little direct interaction between the luminal microbiota and the epithelium - the continuous mucus layer in the colon keeps the surface epithelium out of contact with bacteria and the ileo-caecal valve ensures that the distal small intestine is relatively microbe free. Most interaction takes place at the Peyer's patches in the distal ileum and their smaller colonic equivalents, the lymphoid follicles. Peyer's patches are overlain by a 'dome' epithelium, 5% of whose cells are specialised M (microfold) epithelial cells, which act as the major portal of entry for bacteria. There are no goblet cells in the dome epithelium and M cells have a very sparse glycocalyx allowing easy microbial interaction. It is intriguing that the typical age range for the onset of Crohn's disease (CD) is similar to the age at which the number of Peyer's patches is greatest. Peyer's patches are commonly the sites of the initial lesions in CD and the 'anti-pancreatic' antibody associated with CD has been shown to have as its epitope the glycoprotein 2 that is the receptor for type-1 bacterial fimbrial protein (fimH) on M cells. There are many reasons to believe that the mucosal barrier is critically important in the pathogenesis of inflammatory bowel disease (IBD). These include (i) associations between both CD and ulcerative colitis (UC) with genes that are relevant to the mucosal barrier; (ii) increased intestinal permeability in unaffected relatives of CD patients; (iii) increased immune reactivity against bacterial antigens, and (iv) animal models in which altered mucosal barrier, e.g. denudation of the mucus layer associated with oral dextran sulphate in rodents, induces colitis. Whilst some IBD patients may have genetic factors leading to weakening of the mucosal barrier, it is likely that environmental factors may be even more important. Some may be subtle and indirect, e.g. the effects of stress on the mucosa barrier, whilst others may be more obvious, e.g. the effect of pathogen-related gastroenteritis, known often to act as trigger for IBD relapse. We have also been very interested in the potentially harmful effects of ingested detergents - either by contamination of cutlery by inadequate rinsing or via ingestion of processed foods containing permitted emulsifiers. In vitro and ex vivo studies show that even very small trace amounts of these surfactants can greatly increase bacterial translocation. Implications for therapy are not yet so obvious. We advise our IBD patients to avoid processed foods containing emulsifiers and to rinse their dishes well - whilst accepting that there is no direct evidence yet to support this. Therapies that aim to enhance the mucosal barrier have yet to come to market, but trials of enteric-delivered phosphatidylcholine in UC are promising. The faecal concentration of mucus-degrading bacterial enzymes (particularly proteases, sulphatases and sialidases) correlates with disease activity in UC, and these represent good targets for therapy.

IBD: microbiota manipulation through diet and modified bacteria.

BACKGROUND/AIMS: Crohn's disease (CD) and ulcerative colitis (UC) are both typified by an altered intestinal microbiota, and gene associations imply various defects in the mucosal barrier and in the innate immune response to bacteria. This review aims to assess how alterations in diet or use of modified bacteria could have therapeutic effects in CD or UC. METHODS: A MEDLINE search using the terms 'prebiotic', 'genetically modified bacteria', 'mucosal barrier in association with ulcerative colitis', 'Crohn's disease' or 'microbiota'. RESULTS: A large body of data from in vitro and animal studies shows promise for therapeutic approaches that target the microbiota. Approaches include dietary supplementation with fermentable fibres (prebiotics) and soluble fibres that block bacterial-epithelial adherence (contrabiotics), enhancement of the mucosal barrier with phosphatidylcholine, and use of genetically modified bacteria that express IL-10 or protease inhibitors. Vitamin D supplementation also shows promise, acting via enhancement of innate immunity. Clinical trials have shown benefit with enterically delivered phosphatidylcholine supplementation in UC and near-significant benefit with vitamin D supplementation in CD. CONCLUSION: Strategies that target the microbiota or the host defence against it appear to be good prospects for therapy and deserve greater investment.

The TF-antigen binding lectin from Sclerotium rolfsii inhibits growth of human colon cancer cells by inducing apoptosis in vitro and suppresses tumor growth in vivo.

Glycan array analysis of Sclerotium rolfsii lectin (SRL) revealed its exquisite binding specificity to the oncofetal Thomsen-Friedenreich (Galß1-3GalNAcα-O-Ser/Thr, T or TF) antigen and its derivatives. This study shows that SRL strongly inhibits the growth of human colon cancer HT29 and DLD-1 cells by binding to cell surface glycans and induction of apoptosis through both the caspase-8 and -9 mediated signaling. SRL showed no or very weak binding to normal human colon tissues but strong binding to cancerous and metastatic tissues. Intratumor injection of SRL at subtoxic concentrations in NOD-SCID mice bearing HT29 xenografts resulted in total tumor regression in 9 days and no subsequent tumor recurrence. As the increased expression of TF-associated glycans is commonly seen in human cancers, SRL has the potential to be developed as a therapeutic agent for cancer.

Lessons from diversion studies and antibacterial interventions.

If bacteria cause IBD, then it should be possible to target the bacteria with therapies and cure or at least treat the disease. Discovery of a successful intervention, unless found by chance, will depend on knowing more about which bacteria are involved, where they are and how to remove them. Some evidence for the possible role of bacteria has come from in vivo studies of the effects of diverting the faecal stream away from sites of IBD. Alternative hypotheses arise from the diversion studies that could incriminate other components of the faecal stream that include bile acids and dietary components. Antibiotics will only really be adequately tested when we know what the target bacteria are and where they are, e.g. whether in the lumen or mucosa and whether intracellular or extracellular. Some encouraging responses have been observed, however, with empirical antibiotic therapy.

Randomised placebo-controlled trial of rituximab (anti-CD20) in active ulcerative colitis.

OBJECTIVE: To assess the safety and efficacy of the B lymphocyte (anti-CD20) antibody, rituximab, in the treatment of steroid-resistant moderately active ulcerative colitis (UC). METHODS: A double-blinded, randomised controlled trial with a 2:1 ratio of treatment:placebo (phase II) was carried out in the setting of a University teaching hospital. The subjects comprised 24 patients with moderately active UC who have either failed to respond to conventional corticosteroid therapy or who have relapsed during corticosteroid withdrawal. Five of 8 placebo-treated patients and 12 of 16 rituximab-treated patients were receiving azathioprine, 6-mercaptopurine or methotrexate. Two infusions of rituximab 1 g in 500 ml of 0.9% saline intravenously over 4 h (n=16) or saline placebo (n=8) were given at 0 and 2 weeks. Patients still receiving corticosteroids on entry (placebo group 7/8; rituximab group 14/16) continued a standard steroid tapering regimen. The primary end point was remission (Mayo score ≤ 2) at 4 weeks. Secondary end points included response (Mayo score reduced ≥ 3) at 4 and 12 weeks. RESULTS: Mayo score at entry was higher in rituximab-treated patients (mean 9.19; 95% CI 8.31 to 10.06) than for placebo patients (7.63; 6.63 to 8.62, p=0.03). At week 4 only 1/8 placebo-treated patients and 3/16 rituximab-treated patients were in remission (p=1.0), but 8/16 rituximab-treated patients had responded compared with 2/8 placebo-treated patients, with a median reduction in Mayo score of 2.5 (rituximab) compared with 0 (placebo; p=0.07). This response was only maintained to week 12 in 4/16. Mucosal healing was seen at week 4 in 5/16 rituximab-treated patients and 2/8 placebo-treated patients (non-significant). Rituximab was well tolerated, with one chest infection, three mild infusion reactions plus one case of (probably unrelated) non-fatal pulmonary embolism. CONCLUSIONS Rituximab has no significant effect on inducing remission in moderately active UC not responding to oral steroids. There was a possible short-term response that was not sustained. Rituximab is well tolerated in UC. CLINICAL TRIAL NUMBER: NCT00261118.

Vitamin D, vitamin D-binding protein, free vitamin D and COVID-19 mortality in hospitalized patients.

BACKGROUND: Vitamin D deficiency has been associated with worse coronavirus disease 2019 (COVID-19) outcomes, but circulating 25-hydroxyvitamin D [25(OH)D] is largely bound to vitamin D-binding protein (DBP) or albumin, both of which tend to fall in illness, making the 25(OH)D status hard to interpret. Because of this, measurements of unbound ("free") and albumin-bound ("bioavailable") 25(OH)D have been proposed. OBJECTIVES: We aimed to examine the relationship between vitamin D status and mortality from COVID-19. METHODS: In this observational study conducted in Liverpool, UK, hospitalized COVID-19 patients with surplus sera available for 25(OH)D analysis were studied. Clinical data, including age, ethnicity, and comorbidities, were extracted from case notes. Serum 25(OH)D, DBP, and albumin concentrations were measured. Free and bioavailable 25(OH)D were calculated. Relationships between total, free, and bioavailable 25(OH)D and 28-day mortality were analyzed by logistic regression. RESULTS: There were 472 patients with COVID-19 included, of whom 112 (23.7%) died within 28 days. Nonsurvivors were older (mean age, 73 years; range, 34-98 years) than survivors (mean age, 65 years; range, 19-95 years; P = 0.003) and were more likely to be male (67%; P = 0.02). The frequency of vitamin D deficiency [25(OH)D < 50 nmol/L] was similar between nonsurvivors (71/112; 63.4%) and survivors (204/360; 56.7%; P = 0.15) but, after adjustments for age, sex, and comorbidities, increased odds for mortality were present in those with severe deficiency [25(OH)D < 25 nmol/L: OR, 2.37; 95% CI, 1.17-4.78] or a high 25(OH)D (≥100 nmol/L; OR, 4.65; 95% CI, 1.51-14.34) compared with a 25(OH)D value of 50-74 nmol/L (reference). Serum DBP levels were not associated with mortality after adjustments for 25(OH)D, age, sex, and comorbidities. Neither free nor bioavailable 25(OH)D values were associated with mortality. CONCLUSIONS: Vitamin D deficiency, as commonly defined by serum 25(OH)D levels (<50 nmol/L), is not associated with increased mortality from COVID-19, but extremely low (<25 nmol/L) and high (>100 nmol/L) levels may be associated with mortality risks. Neither free nor bioavailable 25(OH)D values are associated with mortality risk. The study protocol was approved by the London-Surrey Research Ethics Committee (20/HRA/2282).

Complete genome sequence of the Crohn's disease-associated adherent-invasive Escherichia coli strain HM605.

Adherent-invasive Escherichia coli strains are increasingly being associated with intestinal pathologies. Here we present the genome sequence of E. coli HM605, a strain isolated from colonic biopsy specimens of a patient with Crohn's disease.

The role of galectins in colorectal cancer progression.

Galectins constitute a family of 15 mammalian galactoside-binding proteins that share a consensus amino acid sequence in their carbohydrate binding sites. They are multi-functional molecules and are expressed widely in human tissues. Four galectins: galectin -1, -3, -4 and -8 are expressed in the human colon and rectum and their expressions show significant changes during colorectal cancer development and metastasis. These changes in galectin expression correlate with alterations in cancer cell growth, apoptosis, cell-cell and cell-matrix interactions and angiogenesis. This review summaries current knowledge of the expression and roles of these galectins in the progression of human colorectal cancer and discusses the relevance of galectins and their ligands as potential therapeutic targets for cancer treatment.

Bacteria in the pathogenesis of inflammatory bowel disease.

Twin studies have demonstrated the importance of environmental factors in the pathogenesis of inflammatory bowel disease, but progress has been relatively slow in identifying these, with the exception of smoking, which is positively associated with Crohn's disease and negatively associated with ulcerative colitis. Genetic studies have identified risk alleles which are involved in host-bacterial interactions and the mucosal barrier, and evidence is building for a likely pathogenic role for changes in the gut microbiome, with respect to both faecal and mucosa-associated microbiota. Some of these changes may be secondary to inflammation, nevertheless promising new therapeutic targets are beginning to emerge.

Exquisite binding specificity of Sclerotium rolfsii lectin toward TF-related O-linked mucin-type glycans.

Sclerotium rolfsii lectin (SRL), a secretory protein from the soil borne phytopathogenic fungus Sclerotium rolfsii, has shown in our previous studies to bind strongly to the oncofetal Thomson-Friedenreich carbohydrate (Galß1-3GalNAc-ser/thr, T or TF) antigen. TF antigen is widely expressed in many types of human cancers and the strong binding of SRL toward such a cancer-associated carbohydrate structure led us to characterize the carbohydrate binding specificity of SRL. Glycan array analysis, which included 285 glycans, shows exclusive binding of SRL to the O-linked mucin type but not N-linked glycans and amongst the mucin type O-glycans, lectin recognizes only mucin core 1, core 2 and weakly core 8 but not to other mucin core structures. It binds with high specificity to "α-anomers" but not the "ß-anomers" of the TF structure. The axial C4-OH group of GalNAc and C2-OH group of Gal is both essential for SRL interaction with TF disaccharide, and substitution on C3 of galactose by sulfate or sialic acid or N-acetylglucosamine, significantly enhances the avidity of the lectin. SRL differs in its binding to TF structures compared to other known TF-binding lectins such as the Arachis hypogea (peanut) agglutinin, Agaricus bisporus (mushroom) lectin, Jackfruit, Artocarpus integrifolia (jacalin) and Amaranthus caudatus (Amaranthin) lectin. Thus, SRL has unique carbohydrate-binding specificity toward TF-related O-linked carbohydrate structures. Such a binding specificity will make this lectin a very useful tool in future structural as well as functional analysis of the cellular glycans in cancer studies.