Proteomic analysis of rainbow trout (Oncorhynchus mykiss) intestinal epithelia: physiological acclimation to short-term starvation

The intestinal epithelia form the first line of defense against harmful agents in the gut lumen of most monogastric vertebrates, including teleost fishes. Previous investigations into the effect of starvation on the intestinal epithelia of teleost fishes have focused primarily on changes in morphological characteristics and targeted molecular analysis of specific enzymes. The goal of this study was to use a comprehensive approach to help reveal how the intestinal epithelia of carnivorous teleost fishes acclimate to short-term nutrient deprivation. We utilized two-dimensional gel electrophoresis (2-DE) to conduct the proteomic analysis of the mucosal and epithelial layer of the anterior gut intestinal tract (GIT) from satiation fed vs. 4 week starved rainbow trout (Oncorhynchus mykiss). A total of 40 proteins were determined to be differentially expressed and were subsequently picked for in-gel trypsin digestion. Peptide mass fingerprint analysis was conducted using matrix assisted laser desorption time-of-flight/time-of-flight. Nine of the 11 positively identified proteins were directly related to innate immunity. The expression of α-1 proteinase inhibitor decreased in starved vs. fed fish. Also, the concentration of one leukocyte elastase inhibitor (LEI) isomer decreased in starved fish, though the concentration of another LEI isomer increased in due to starvation. In addition, starvation promoted an increased concentration of the important xenobiotic-transporter p-glycoprotein. Finally, starvation resulted in a significant increase in type II keratin E2. Overall, our results indicate that starvation promoted a reduced capacity to inhibit enzymatic stress but increased xenobiotic resistance and paracellular permeability of epithelial cells in the anterior intestine of rainbow trout.

Proteomic analysis reveals field-wide changes in protein expression in the morphologically normal mucosa of patients with colorectal neoplasia

Models for the pathogenesis of colorectal cancer tend to focus on the localized lesion, with less attention paid to changes in normal-appearing mucosa. Here we used two-dimensional gel electrophoresis and mass spectrometry to define patterns of protein expression in morphologically normal colonic mucosa from 13 healthy subjects, 9 patients with adenomatous polyps, and 9 with cancer. Tumor samples were also compared with the normal mucosa. Systematic gel comparisons identified a total of 839 spots that differed significantly between one or more groups (P < 0.05). Principle component analysis indicated that the first three components accounted for approximately 37% of the total variation and provided clear evidence that flat mucosa from healthy subjects differed significantly from that of patients with polyps or cancer. Sixty-one proteins differed significantly between mucosa from healthy subjects and all other tissue types, and 206 differed significantly between healthy mucosa and polyp mucosa. Several of the proteins showing significant underexpression in tumor tissue were cytokeratins and other cytoskeletal components. In contrast, cytokeratins, including several isoforms of cytokeratin 8, were overexpressed in apparently normal mucosa from polyp and cancer patients compared with mucosa from healthy subjects. These findings indicate that protein expression in the apparently normal colonic mucosal field is modified in individuals with neoplastic lesions at sites distant from the lesion. Recognition and further characterization of this field effect at the molecular level may provide protein biomarkers of susceptibility to colorectal cancer and facilitate development of hypotheses for the role of diet and other environmental factors in its causation.

Fecal alpha-1-antitrypsin excretion in children with diarrhea

BACKGROUND

The aim of this study was to compare the concentration and immunoelectrophoretic characterization of alpha-1-antitrypsin (AAT) excreted in random fecal samples in children with acute and chronic diarrhea and in control groups.

METHODS

Thirty-two children with diarrhea and 23 healthy children were evaluated. The concentration and characterization of AAT were determined by radial immunodiffusion and crossed immunoelectrophoresis, respectively.

RESULTS

The increase in the concentration of fecal AAT was more than the upper limit for the control group (1.25 mg/g of dry stool mass) in the patients with chronic infectious diarrhea and in 52% of those with chronic non-infectious diarrhea but not in those with acute diarrhea, infectious or non-infectious. Immunoelectrophoretic analysis showed two forms of fecal AAT in both sick and healthy children. The alterations in the concentration of fecal AAT did not correlate with the immunoelectrophoretic pattern of AAT.

CONCLUSION

Our results suggest that the determination of fecal AAT could give clinically useful information about the difference between infectious and non-infectious diarrhea and the activity of characterizing disease with diarrhea.

Role of antiproteolytic heparin-binding serum protein(s) in modulating the levels of sialyl- and galactosyltransferase activity released during the incubation of rat jejunal slices

1. Sialyltransferase released into the medium during the incubation of rat jejunal slices in serum-free buffer, was susceptible to proteolytic degradation. Heat inactivated horse serum or its antiproteolytic heparin-binding fraction was found to be necessary in determining the activity of sialyltransferase released (Nadkarni et al., 1991). 2. In the present study, we have shown that heat inactivated rat serum (HRS) or its antiproteolytic heparin-binding fraction (HBF) had a role in determining the sialyltransferase activity released during jejunal slice incubations. 3. Galactosyltransferase was also released during incubations, but was not proteolytically degraded and the presence of HRS or HBF in incubations did not alter the levels of galactosyltransferase activity released. 4. Trypsin activity in serum-free incubation medium was higher compared to medium containing HRS. 5. Addition of serum-free medium obtained from 4 hr incubations of the jejunal slices, to medium obtained from parallel incubations done in the presence of HRS, caused inhibition of sialyl- but not galactosyltransferase activity. 6. In jejunal homogenates stored at -20 degrees C, sialyltransferase activity was decreased during 0-45 days of storage, whereas galactosyltransferase activity remained fairly stable for upto 56 days. 7. Inclusion of HRS or HBF in homogenates resulted in higher sialyl- but not galactosyltransferase activity compared to serum-free homogenate samples. 8. The results suggest that HRS or its antiproteolytic heparin-binding proteins have a role in determining the sialyltransferase activity released from the jejunal slices. In contrast galactosyltransferase released was not susceptible to proteolysis, and HRS or HBF was not required to express its activity.

A simple method for the measurement of different forms of alpha 1 proteinase inhibitor in the faeces of patients with Crohn's disease

Alpha-1 proteinase inhibitor (alpha 1PI), formerly named alpha 1-antitrypsin, is excreted in the faeces of patients with Crohn's disease as isoforms clearly separated by SDS-PAGE and immunoblot analysis. Relapses in Crohn's disease are generally associated with the appearance in faeces of M(rs) 51,000 and 45,000 glycosylated forms of alpha 1PI, as compared with normal subjects and most of the patients in quiescent phases of their disease who excrete an M(r) 38,000 unglycosylated form of alpha 1PI. We used their differential Concanavalin-A reactivity to design a specific test. The proposed assay is potentially helpful for the follow-up of patients under therapy and for early recognition of attacks of Crohn's disease.

Evaluation of intestinal clearance and faecal excretion of alpha 1-antiproteinase and immunoglobulins during Crohn's disease and ulcerative colitis

The intestinal clearance of alpha 1-antiproteinase, monomeric IgA and IgG, and the daily fecal output of polymeric IgA and IgM were investigated in patients with inflammatory bowel diseases (inactive and active Crohn's disease, ulcerative colitis) and in a control group. The intestinal clearance of alpha 1-antiproteinase was significantly increased in all patients with inflammatory bowel diseases (p less than 0.01), irrespective of the grade of the disease. In contrast, increases in intestinal clearances of monomeric IgA and IgG were more closely related to the severity of the intestinal lesions. The associate determination of these three quantities should therefore be of interest for monitoring the degree of intestinal bowel inflammation. Faecal output of polymeric IgA was significantly increased in active intestinal disease (p less than 0.01), whereas faecal IgM levels were not. The determination of the faecal output of polymeric IgA should contribute to the assessment of the activity of inflammatory bowel diseases, and may provide insight into the activation of the mucosal immune system.

Structural heterogeneity of faecal alpha 1 antitrypsin shown by immunoblot analysis in patients with Crohn's disease

Faecal alpha 1 antitrypsin was determined in 34 patients with Crohn's disease and in 19 healthy subjects by immune nephelometry. A structural analysis of faecal alpha 1 antitrypsin was carried out using immunoblot analysis under non-reducing conditions. Native serum alpha 1 antitrypsin migrated with an apparent molecular weight of 45 kDa. Proteolytic alpha 1 antitrypsin fragments (5-42 kDa) were specifically immunostained in 13/19 and 22/34 stool samples from control subjects and from patients with Crohn's disease respectively. There was a weak correlation (r = 0.47; p less than 0.02) between the molecular weight of fragmented alpha 1 antitrypsin and the faecal concentration in both groups, indicating that alpha 1 antitrypsin inhibits its own proteolysis by intestinal proteases in a dose dependent way. The incidence of polymeric forms (greater than 45 kDa) was similar in patients (10/34) and control subjects (5/19). In only one case in each group was the native serum form of alpha 1 antitrypsin found in faeces. We conclude that faecal alpha 1 antitrypsin differs structurally from the native serum form. Immunochemical measurements, therefore, reflect rather than represent faecal concentrations of alpha 1 antitrypsin. The controversial results in published reports may be partly explained by these findings. The molecular heterogeneity of faecal alpha 1 antitrypsin is not specifically associated with Crohn's disease.