Anti-α4β7 therapy targets lymphoid aggregates in the gastrointestinal tract of HIV-1-infected individuals

Gut homing CD4⁺ T cells expressing the integrin α4β7 are early viral targets and contribute to HIV-1 pathogenesis, likely by seeding the gastrointestinal (GI) tract with HIV. Although simianized anti-α4β7 monoclonal antibodies have shown promise in preventing or attenuating the disease course of simian immunodeficiency virus in nonhuman primate studies, the mechanisms of drug action remain elusive. We present a cohort of individuals with mild inflammatory bowel disease and concomitant HIV-1 infection receiving anti-α4β7 treatment. By sampling the immune inductive and effector sites of the GI tract, we have discovered that anti-α4β7 therapy led to a significant and unexpected attenuation of lymphoid aggregates, most notably in the terminal ileum. Given that lymphoid aggregates serve as important sanctuary sites for maintaining viral reservoirs, their attrition by anti-α4β7 therapy has important implications for HIV-1 therapeutics and eradication efforts and defines a rational basis for the use of anti-α4β7 therapy in HIV-1 infection.

The current state of the art for biological therapies and new small molecules in inflammatory bowel disease

The emergence of biologic therapies is arguably the greatest therapeutic advance in the care of inflammatory bowel disease (IBD) to date, allowing directed treatments targeted at highly specific molecules shown to play critical roles in disease pathogenesis, with advantages in potency and selectivity. Furthermore, a large number of new biologic and small-molecule therapies in IBD targeting a variety of pathways are at various stages of development that should soon lead to a dramatic expansion in our therapeutic armamentarium. Additionally, since the initial introduction of biologics, there have been substantial advances in our understanding as to how biologics work, the practical realities of their administration, and how to enhance their efficacy and safety in the clinical setting. In this review, we will summarize the current state of the art for biological therapies in IBD, both in terms of agents available and their optimal use, as well as preview future advances in biologics and highly targeted small molecules in the IBD field.

Efficient long-term depletion of CD20+ B cells by rituximab does not affect gut-resident plasma cells

The vast majority of antibody-producing B cells are located within the gastrointestinal tract and are key players in maintaining homeostasis. The failure of rituximab, a potent B cell-depleting agent, to ameliorate ulcerative colitis in a single clinical trial has dampened enthusiasm to study B cells in patients with inflammatory bowel disease (IBD). However, several lines of evidence suggest that intestinal B cells may be affected in IBD. Additionally, the pathophysiological mechanisms underlying rituximab's lack of efficacy in IBD remain unclear. Here, on the basis of detailed immunophenotyping of a patient who underwent a colonoscopy 6 months after the end of rituximab-based therapy, we observed that rituximab did not deplete colon-resident plasma cells (PCs) while ablating all CD20⁺ B cells in tissues and in the circulation. On the basis of these observations, we propose that one factor underlying the lack of efficacy of rituximab relates to the fact that it does not affect the entire B cell compartment in tissues, sparing the intestinal-resident PCs while effectively depleting CD20⁺ B cell populations. Thus, we contend that, despite the results of the Rituximab study, there is a need for more intensive B cell-oriented research in inflammatory disorders, including IBD.

Alopecia areata universalis complicating daclizumab therapy for uveitis

Alopecia areata (AA) is a complication of biologic therapy with several anti-tumor necrosis factor (TNF) inhibitors and efalizumab for the treatment of various autoimmune diseases. We report the case of a 51-year-old woman who developed AA universalis while undergoing treatment with daclizumab, an immunosuppressive biologic therapy, administered for treatment of inflammatory ocular disease. Although immunomodulatory agents that function by interfering with T helper cell stimulation are expected to impede autoimmune-related processes, we believe that daclizumab may be causally related to the development of AA.