Human colonic goblet cells. Demonstration of distinct subpopulations defined by mucin-specific monoclonal antibodies.

We studied glycoprotein content of human colonic goblet cells, using a library of monoclonal antibodies (MAbs) directed against purified human colonic mucin (HCM). Using indirect immunofluorescence (IIF), we found that 17 of 23 anti-HCM MAbs stained some or all goblet cells of normal human colonic mucosa. We observed a variety of cellular staining patterns, including (a) diffuse (homogeneous) staining of intracellular mucin, (b) speckled (inhomogeneous) staining of mucin droplets, (c) peripheral staining of intracellular droplets, (d) cytoplasmic staining of goblet cells, and (e) apical (luminal) surface staining. Staining patterns were not associated with particular HCM species. In addition to variable patterns of IIF within individual cells, anti-HCM MAbs varied in the proportion of goblet cells stained. Some MAbs stained all goblet cells, while others stained a limited number of goblet cells. Although each goblet cell contained more than one type mucin, HCM species III, and IV and V appeared to exist in mutually exclusive goblet cell populations and it was possible to define at least seven subpopulations of goblet cells in colonic mucosa by their content of various combinations of HCM species. Anti-HCM MAbs stained goblet cells from other sites within the gastrointestinal tract to a varying extent. Anti-HCM MAbs also showed extensive cross-reactivity with rodent, rabbit, and monkey colonic mucosa. However, several anti-HCM MAbs stained only human colonic mucosa. These data show that human colonic mucosa contains discrete subpopulations of goblet cells that produce distinctive combinations of specific mucin glycoprotein species.     

Patent foramen ovale: a nonfunctional embryological remnant or a potential cause of significant pathology?

A patent foramen ovale (PFO) is an embryological remnant found in 27% of adults. It is a potential right-to-left intracardiac shunt. Shunting may be the result of reversal in the interatrial pressure gradient or abnormal streaming of blood in the right atrium. The pathologic consequences of right-to-left shunting include hypoxemia and paradoxical embolism. PFO may exacerbate preexisting hypoxemia or be its primary cause. Paradoxical embolism through a PFO is well documented. Its role in cryptogenic stroke remains controversial. A PFO may be detected by both invasive and noninvasive techniques. Contrast transesophageal echocardiography with provocative maneuvers is the diagnostic method of choice allowing visualization of the shunt. Patients with cryptogenic stroke should be screened for a PFO. If detected, noninvasive studies for deep vein thrombosis are recommended. Treatment must be tailored to the presentation. Surgical or transcatheter closure is recommended for hypoxemia. Prevention of venous embolism (air or thrombus) with or without closure of the PFO is recommended for paradoxical embolism.     

Combination of ABO blood group incompatibility and glucose-6-phosphate dehydrogenase deficiency: effect on hemolysis and neonatal hyperbilirubinemia

The incidence (%) of hyperbilirubinemia (serum bilirubin ≥257 μmol/l) was similar in neonates with a combination of ABO incompatibility and glucose-6-phosphate dehydrogenase (G-6-PD) deficiency (45%), with ABO incompatibility (54%) or G-6-PD deficiency (37%), alone (ns). Carboxyhemoglobin values, corrected for inspired CO, were similarly elevated in all three groups (0.87 ± 0.32%, 0.82 ± 0.29%, 0.76 ± 0.18%, respectively, ns), but correlated with bilirubin only in those with ABO incompatibility alone. ABO-incompatible/G-6-PD-deficient neonates, compared with those with either condition alone, are not at increased risk for hemolysis or hyperbilirubinemia.     

Differential alteration in intestinal epithelial cell expression of toll-like receptor 3 (TLR3) and TLR4 in inflammatory bowel disease

Initiation and perpetuation of the inflammatory intestinal responses in inflammatory bowel disease (IBD) may result from an exaggerated host defense reaction of the intestinal epithelium to endogenous lumenal bacterial flora. Intestinal epithelial cell lines constitutively express several functional Toll-like receptors (TLRs) which appear to be key regulators of the innate response system. The aim of this study was to characterize the expression pattern of TLR2, TLR3, TLR4, and TLR5 in primary intestinal epithelial cells from patients with IBD. Small intestinal and colonic biopsy specimens were collected from patients with IBD (Crohn's disease [CD], ulcerative colitis [UC]) and controls. Non-IBD specimens were assessed by immunofluorescence histochemistry using polyclonal antibodies specific for TLR2, TLR3, TLR4, and TLR5. Primary intestinal epithelial cells (IEC) of normal mucosa constitutively expressed TLR3 and TLR5, while TLR2 and TLR4 were only barely detectable. In active IBD, the expression of TLR3 and TLR4 was differentially modulated in the intestinal epithelium. TLR3 was significantly downregulated in IEC in active CD but not in UC. In contrast, TLR4 was strongly upregulated in both UC and CD. TLR2 and TLR5 expression remained unchanged in IBD. These data suggest that IBD may be associated with distinctive changes in selective TLR expression in the intestinal epithelium, implying that alterations in the innate response system may contribute to the pathogenesis of these disorders.