Clostridium difficile recurrence is characterized by pro-inflammatory peripheral blood mononuclear cell (PBMC) phenotype.

Clostridium difficile infection (CDI) is a prevalent nosocomial and increasingly community-acquired problem. Little is known about the productive cellular response in patients. We used flow cytometry to define inflammatory (Th1 and Th17) and regulatory [Foxp3(+) T-regulatory (Treg)] cells present in circulating peripheral blood mononuclear cells (PBMC) from CDI patients. We consented 67 inpatients that tested either positive or negative for CDI and 16 healthy controls and compared their PBMC phenotypes. PBMC were collected, isolated, and stained for CD3, CD8 and either IL17 (Th17), IFN-γ (Th1) or Foxp3 (Treg) and analysed using flow cytometry. Twenty thousand events were collected in the lymphocyte gate (gate 1) and T-cell phenotypes were defined. CDI patients who clear the primary initial infection have greater numbers of non-CD3 PBMC. CDI patients who develop recurrence of CDI have a greater percentage of CD3(+)CD8(+), CD3(+)CD4(+)Foxp3 and fewer low granular CD3(-)Foxp3(+) PBMC. These patients have greater numbers of IFN-γ-producing lymphocytes, as well as PBMC phenotypes represented by increased IFN-γ- and IL17-co-expressing CD4(+)CD3(+). This initial pro-inflammatory phenotype decreases with repeated recurrence, demonstrating importance of timing of sample collection and history of symptoms. Patients with a history of recurrence had increased Foxp3(+)CD3(+)CD4(+) and IL17(+)CD3(+)CD4(+) populations. Hence, CDI recurrence is hallmarked by greater numbers of circulating CD3(+) lymphocytes skewed towards a Th1/Th17 inflammatory population as well as possible immune plasticity (Th17/Treg).

Characterization of acetylcholinesterase in Caco-2 cells.

Acetylcholinesterase (acetylcholine hydrolase, EC 3.1.1.7) was solubilized from cultured Caco-2 cells. It was established that this enzyme activity is acetylcholinesterase by substrate specificity (acetylthiocholine, acetyl-beta-methylthiocholine>propionylthiocholine>butyrylthiocholine), substrate inhibition, and specificity of inhibitors (BW284c51>iso-OMPA). The acetylcholinesterase activity increased proportional to the degree of differentiation of the cells. Most of the enzyme was membrane bound, requiring detergent for solubilization, and the active site faced the external fluid. Only one peak of activity, which corresponded to a monomeric form, could be detected on linear sucrose density gradients. The sedimentation of this form of the enzyme was shifted depending on whether Triton X-100 or Brij 96 detergent was used. These results indicate that the epithelial-derived Caco-2 cells produce predominantly an amphiphilic, monomeric form of acetylcholinesterase that is bound to the plasma membrane and whose catalytic center faces the extracellular fluid.