Crohn’s disease and ulcerative colitis affect an increasing number of patients. A variety of medical options exist for the treatment of these diseases including immune suppressants and biologic therapies. Unfortunately, these agents are associated with adverse events ranging from mild nuisance symptoms to potentially life-threatening complications including infections and malignancies. This review discusses adverse events associated with azathioprine, mercaptopurine, and methotrexate as well as anti-TNF-α and anti-integrin antibodies. In addition, adverse events associated with combination therapy are discussed as are clinical scenarios in which it may be reasonable to discontinue or de-escalate drug therapy. It is the responsibility of the treating gastroenterologist to effectively communicate the benefits and risks of therapy with patients; this review offers strategies that may assist providers in communicating risk with patients in addition to offering our perspective on whether modification or cessation of therapy can be considered.

Crohn’s disease and ulcerative colitis are chronic, relapsing inflammatory disorders of the GI tract. In both Crohn’s disease and ulcerative colitis, leukocytic infiltration of the mucosa is associated with epithelial damage. Recently, monoclonal antibodies directed against cell adhesion molecules (CAMs) involved in leukocyte extravasation have been developed. Natalizumab, the first drug brought to market targeting CAMs, is clinically effective but is associated with serious adverse effects including the uncommon, but often fatal, neurological disease progressive multifocal leukoencephalopathy. Vedolizumab targets a subset of the CAMs blocked by natalizumab and is currently in Phase III trials to study its efficacy and safety in patients with inflammatory bowel disease. Here, we discuss the current treatment options available for patients with Crohn’s disease or ulcerative colitis, the history of CAM inhibitors, the current state of development of vedolizumab and its future role in inflammatory bowel disease, if approved by regulatory agencies.

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Despite increased appreciation for the role of nicotinic receptors in the modulation of and response to inflammation, the contribution of muscarinic receptors to mucosal homeostasis, clearance of enteric pathogens, and modulation of immune cell function remains relatively undefined. Uninfected and Nippostrongylus brasiliensis-infected wild-type and type 3 muscarinic receptor (M3R)-deficient (Chrm3(-/-)) mice were studied to determine the contribution of M3R to mucosal homeostasis as well as host defense against the TH2-eliciting enteric nematode N. brasiliensis Intestinal permeability and expression of TH1/TH17 cytokines were increased in uninfected Chrm3(-/-) small intestine. Notably, in Chrm3(-/-) mice infected with N. brasiliensis, small intestinal upregulation of TH2 cytokines was attenuated and nematode clearance was delayed. In Chrm3(-/-) mice, TH2-dependent changes in small intestinal function including smooth muscle hypercontractility, increased epithelial permeability, decreased epithelial secretion and absorption, and goblet cell expansion were absent despite N. brasiliensis infection. These findings identify an important role for M3R in host defense and clearance of N. brasiliensis, and support the expanding role of cholinergic muscarinic receptors in maintaining mucosal homeostasis.

Parasitic enteric nematodes induce a type 2 immune response characterized by increased production of Th2 cytokines, IL-4 and IL-13, and recruitment of alternatively activated macrophages (M2) to the site of infection. Nematode infection is associated with changes in epithelial permeability and inhibition of sodium-linked glucose absorption, but the role of M2 in these effects is unknown. Clodronate-containing liposomes were administered prior to and during nematode infection to deplete macrophages and prevent the development of M2 in response to infection with Nippostrongylus brasiliensis. The inhibition of epithelial glucose absorption that is associated with nematode infection involved a macrophage-dependent reduction in SGLT1 activity, with no change in receptor expression, and a macrophage-independent down-regulation of GLUT2 expression. The reduced transport of glucose into the enterocyte is compensated partially by an up-regulation of the constitutive GLUT1 transporter consistent with stress-induced activation of HIF-1α. Thus, nematode infection results in a “lean” epithelial phenotype that features decreased SGLT1 activity, decreased expression of GLUT2 and an emergent dependence on GLUT1 for glucose uptake into the enterocyte. Macrophages do not play a role in enteric nematode infection-induced changes in epithelial barrier function. There is a greater contribution, however, of paracellular absorption of glucose to supply the energy demands of host resistance. These data provide further evidence of the ability of macrophages to alter glucose metabolism of neighboring cells.