Inverse Association Between Circulating Monocyte-Platelet Complexes and Inflammation in Ulcerative Colitis Patients.

Background: Circulating monocytes from active ulcerative colitis (UC) patients produced high levels of tumor necrosis factor-alpha(TNFα) and interleukin(IL)-6 after Toll-like receptors (TLR) stimulation. Since platelets (PLT) can bind to leukocytes, thereby decreasing inflammatory cytokine production, UC patients may exhibit different levels of monocyte-platelet complexes depending on disease activity. Methods: We compared among healthy donors, active (onset flare and relapse), and inactive UC patients the presence of circulating monocyte-platelet complexes (CD14+PLT+) and membrane CD162 expression by flow cytometry. Lipopolysaccharide- binding protein, TNFα, and IL-10 were compared by ELISA. Binding of CD14+PLT+ to human umbilical vein endothelial cells (HUVECs) were analyzed by immunofluorescence. Results: Onset flare UC patients had the lowest levels of CD14+PLT+. Membrane CD162, crucial for the PLT binding, was downregulated only on monocytes from onset flare UC patients. Membrane CD162 expression on CD14+ cells inversely correlated with lipopolysaccharide binding protein levels. As an expected consequence, more CD14+PLT+ than CD14+PLT- from onset flare UC patients bound to activated HUVECs. TNFα tended to negatively correlate with CD14+PLT+ in relapse and inactive UC patients, whereas IL-10 positively correlated with CD14+PLT+ in all UC patients (r = -0.43, P = 0.1 and r = 0.61, P = 0.01, respectively). The anti-inflammatory role of PLT binding to monocytes was confirmed in cocultures of PLT and monocytes. These cocultures increased the percentage of CD14+PLT+ and IL-10 production, and decreased TNFα production. These anti-inflammatory effects were abolished when we blocked the binding of PLT with neutralizing anti-CD62P antibody. Conclusions: Decreased CD162 expression associated with endotoxemia reduced the binding of PLT to monocytes through membrane CD162-CD62P, favoring the inflammatory response of onset flare UC patients.

Inflammatory bowel disease in travelers: choosing the right vaccines and check-ups.

The majority of patients with inflammatory bowel disease (IBD) achieve good control of the inflammatory activity using available therapies. When remission is achieved and quality of life recovered, a considerable proportion of IBD patients express their desire to travel abroad, be it for business, academic or leisure purposes. Their physicians should help and encourage them whenever possible. However, preventive measures are warranted to minimize the risk, since IBD patients are exposed to the same infections affecting the general population, plus opportunistic infections (OI) related to the immunosuppression. There are a large number of potential OI that might affect patients with IBD. The true prevalence of these infections is unknown, and can vary from country to country. Therefore, reactivation or de novo acquisition of infections such as tuberculosis, malaria, and viral hepatitis will be much more frequent in endemic areas. Therefore, physicians should be aware of these aspects when planning specific preventive measures for patients traveling to a particular country. This includes good control of environmental exposure, chemoprophylaxis when indicated, and the use of a specific vaccination program to prevent endemic infections. In addition, it should be noted that, though the risk of acquiring an infectious disease is probably greater for IBD patients traveling from a developed to a developing country, the inverse situation can also occur; it depends on the previous acquired immunity of the host against infections in any particular environment.