Unique gut microbiota compositions have been associated with inflammatory diseases, but identifying gut bacterial functions linked to immune activation in humans remains challenging. Translocation of pathogens from mucosal surfaces into peripheral tissues can elicit immune activation, although whether and which gut commensal bacteria translocate in inflammatory diseases is difficult to assess. We report that a subset of commensal gut microbiota constituents that translocate across the gut barrier in mice and humans are associated with heightened systemic immunoglobulin G (IgG) responses. We present a modified high-throughput, culture-independent approach to quantify systemic IgG against gut commensal bacteria in human serum samples without the need for paired stool samples. Using this approach, we highlight several commensal bacterial species that elicit elevated IgG responses in patients with inflammatory bowel disease (IBD) including taxa within the clades Collinsella, Bifidobacterium, Lachnospiraceae, and Ruminococcaceae. These and other taxa identified as translocating bacteria or targets of systemic immunity in IBD concomitantly exhibited heightened transcriptional activity and growth rates in IBD patient gut microbiomes. Our approach represents a complementary tool to illuminate interactions between the host and its gut microbiota and may provide an additional method to identify microbes linked to inflammatory disease.

While the microbiota has been associated with diseases states, how specific alterations in composition, function, or localization contribute to pathologies remains unclear. The ability of defined microbes to translocate has been linked to diseases including inflammatory bowel disease (IBD) and was shown to promote responses to immune checkpoint therapy. However, scalable and unbiased tools to uncover microbes with enhanced ability to translocate are limited. Herein, we developed an approach to utilize systemic IgG in an unbiased, culture-independent, and high-throughput fashion as a biomarker to identify gut microbiota members that are capable of translocation across the gastrointestinal barrier. We validate these findings in a cohort of human subjects, and highlight a number of microbial taxa against which elevated IgG responses are unique to subjects with IBD including Collinsella, Bifidobacterium, Faecalibacterium, and Blautia spp . Collinsella and Bifidobacterium taxa identified as translocators and targets of immunity in IBD also exhibited heightened bacterial activity and growth rates in Crohn’s disease subjects. Our approach may represent a complementary tool to illuminate privileged interactions between host and its microbiota, and may provide an additional lens by which to uncover microbes linked to disease processes. h4>One Sentence Summary/h4> Circulating microbiota-specific IgG can identify gut microbiota constituents capable of crossing the gut barrier.

Despite the controversy in mechanism, rodent and clinical studies have demonstrated beneficial effects of stem/progenitor cell therapy after myocardial infarction (MI). In a rat ischaemic reperfusion MI model, we investigated the effects of immunomodification of CD 34(+) cells on heart function and myocardial conduction. Bispecific antibody (BiAb), consisting of an anti-myosin light chain antibody and anti-CD45 antibody, injected intravenously was used to direct human CD34(+) cells to injured myocardium. Results were compared to echocardiography guided intramyocardial (IM) injection of CD34(+) cells and PBS injected intravenously. Treatment was administered 2 days post MI. Echocardiography was performed at 5 weeks and 3 months which demonstrated LV dilatation prevention and fractional shortening improvement in both the BiAb and IM injection approaches, with BiAb achieving better results. Histological analyses demonstrated a decrease in infarct size and increase in arteriogenesis in both BiAb and IM injection. Electrophysiological properties were studied 5 weeks after treatments by optical mapping. Conduction velocity (CV), action potential duration (APD) and rise time were significantly altered in the MI area. The BiAb treated group demonstrated a more normalized activation pattern of conduction and normalization of CV at shorter pacing cycle lengths. The ventricular tachycardia inducibility was lowest in the BiAb treatment group. Intravenous administration of BiAb offers an effective means of stem cell delivery for myocardial repair post-acute MI. Such non-invasive approach was shown to offer a distinct advantage to more invasive direct IM delivery.
© 2015 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

The CCR5 chemokine receptor is crucial for human immunodeficiency virus type 1 (HIV-1) infection, acting as the principal coreceptor for HIV-1 entry and transmission and is thus an attractive target for antiviral therapy. Studies have suggested that CCR5 surface density and its conformational changes subsequent to virion engagement are rate limiting for entry, and consequently, infection. Not all CCR5 antibodies inhibit HIV-1 infection, suggesting a need for more potent reagents. Here we evaluated full length single chain (FLSC) IgG1, a novel IgG-CD4-gp120(BAL) fusion protein with several characteristics that make it an attractive candidate for treatment of HIV-1 infections, including bivalency and a potentially increased serum half-life over FLSC, the parental molecule. FLSC IgG1 binds two domains on CCR5, the N-terminus and the second extracellular loop, lowering the levels of available CCR5 viral attachment sites. Furthermore, FLSC IgG1 synergizes with Maraviroc (MVC), the only licensed CCR5 antagonist. In this study, we used both microscopy and functional assays to address the mechanistic aspects of the interactions of FLSC IgG1 and MVC in the context of CCR5 conformational changes and viral infection. We used a novel stochastic optical reconstruction microscopy (STORM), based on high resolution localization of photoswitchable dyes to visualize direct contacts between FLSC IgG1 and CCR5. We compared viral entry inhibition by FLSC IgG1 with that of other CCR5 blockers and showed FLSC IgG1 to be the most potent. We also showed that lower CCR5 surface densities in HIV-1 infected primary cells result in lower FLSC IgG1 EC50 values. In addition, CCR5 binding by FLSC IgG1, but not CCR5 Ab 2D7, was significantly increased when cells were treated with MVC, suggesting MVC allosterically increases exposure of the FLSC IgG1 binding site. These data have implications for future antiviral therapy development.
Copyright © 2014 Elsevier B.V. All rights reserved.

Glioblastoma (GB) is a devastating disease for which new treatment modalities are needed. Efficacious therapy requires the removal of stem-cell like cells, these cells drive tumor progression because of their ability to self-renew and differentiate. In glioblastoma, the GB stem-like cells (GSC) form a small population of tumor cells and possess high resistance to chemo and radiation therapies. To assess the sensitivity of GSC to reovirus-mediated cytolysis, a panel of GSC cultures was exposed to wild-type reovirus Type 3 Dearing (T3D) and its junction adhesion molecule-A (JAM-A)-independent mutant, jin-1. Several parameters were evaluated, including the fraction of cells expressing the JAM-A reovirus receptor, the fraction of cells synthesizing reovirus proteins, the number of infectious reovirus particles required to reduce cell viability, the amount of infectious progeny reovirus produced and the capacity of the reoviruses to infect the GSC in 3-dimensional (3D) tumor cell spheroids. Our data demonstrate a marked heterogeneity in the susceptibility of the cultures to reovirus-induced cytolysis. While in monolayer cultures the jin-1 reovirus was generally more cytolytic than the wild-type reovirus T3D, in the 3D GSC spheroids, these viruses were equally effective. Despite the variation in reovirus sensitivity between the different GSC cultures, our data support the use of reovirus as an oncolytic agent. It remains to be established whether the variation in the reovirus sensitivity correlates with a patient's response to reovirus therapy. Moreover, our data show that the expression of the JAM-A receptor is not a major determinant of reovirus sensitivity in 3D GSC cultures.