Anti-α4β7 mAb Research Articles

Effects of a gut-selective integrin-targeted therapy in male mice exposed to early immune activation, a model for the study of autism spectrum disorder

To clarify the role of gut mucosal immunity in ASD, we evaluated, in the early-life immune activation (EIA) mouse model, the effects of administration of a monoclonal antibody directed against the integrin alpha4 beta7 (α4β7 mAb), blocking the leukocyte homing into the gut mucosa. EIA is a double-hit variant of the maternal immune-activation (MIA) model, including both prenatal (Poly I:C) and postnatal (LPS) immune challenges.In C57BL6/J EIA male adult offspring mice, IL-1β and IL-17A mRNA colonic tissue content increased when compared with controls. Cytofluorimetric analyses of lymphocytes isolated from mesenteric lymph-nodes (MLN) and spleens of EIA mice show increased percentage of total and CD4+α4β7+, unstimulated and stimulated IL-17A+ and stimulated IFN-γ+ lymphocytes in MLN and CD4+α4β7+ unstimulated and stimulated IL-17A+ and stimulated IFN-γ+ lymphocytes in the spleen. Treatment with anti-α4β7 mAb in EIA male mice was associated with colonic tissue IL-1β, and IL-17A mRNA content and percentage of CD4+ IL-17A+ and IFN-γ+ lymphocytes in MLN and spleens comparable to control mice. The anti-α4β7 mAb treatment rescue social novelty deficit showed in the three-chamber test by EIA male mice. Increased levels of IL-6 and IL-1β and decreased CD68 and TGF-β mRNAs were also observed in hippocampus and prefrontal cortex of EIA male mice together with a reduction of BDNF mRNA levels in all brain regions examined. Anti-α4β7 mAb treatment restored the expression of BDNF, TGF-β and CD68 in hippocampus and prefrontal cortex.Improvement of the gut inflammatory status, obtained by a pharmacological agent acting exclusively at gut level, ameliorates some ASD behavioral features and the neuroinflammatory status. Data provide the first preclinical indication for a therapeutic strategy against gut-immune activation in ASD subjects with peripheral increase of gut-derived (α4β7+) lymphocytes expressing IL-17A.

P061 Response to anti-α4β7 therapy in Ulcerative colitis is associated with lymphoid aggregate attrition through impaired recruitment of naïve lymphocytes

Abstract Background Vedolizumab (VDZ) is a frontline drug for Ulcerative colitis (UC) and Crohn’s disease (CD) that targets integrin α4β7, a gut-homing receptor. Despite significant use, the mechanism(s) of action (MOA) of VDZ remain unclear. Methods Peripheral blood mononuclear cells (PBMC) from UC patients (n=43) and paired intestinal biopsies in a subset (n=12) were examined at week 0 (pre-infusion) and 14, by multiparameter flow cytometry (FC). TNF inhibitor (TNFi)-treated UC patients served as controls. Drug MOA was further examined in detail in murine models using single-cell RNA-seq, FC, conventional and immunofluorescent microscopy (IF). Photoconvertible (Kikumi) mice were used to study cellular trafficking after anti-α4β7 (DATK32) antibody (mAb) administration. Two distinct UC cohorts (n=42 and n=21 respectively) were used to correlate GI immune alterations following VDZ with mucosal healing. Results A significant decrease of colonic and ileal naïve B and T cells was noted in VDZ- but not in TNFi-treated patients (Fig 1A), while total T cell-frequencies were unchanged. Circulating gut-homing plasmablasts (β7+) were significantly decreased post-VDZ. Peyer’s patches (PP) in anti-α4β7-treated mice showed a rapid loss of cellularity associated with decreased follicular naïve B cells (Fig 1B). Single-cell RNA-seq also demonstrated a significant loss of follicular B cells, including a unique population of epithelium-associated B cells following anti-α4β7 mAb. In Kikumi mice, anti-α4β7 mAb impaired non-photoconverted follicular B cells and T cells into photoconverted PPs (Fig 1C) demonstrating that loss of PP cellularity was due to impaired cellular ingress. In VDZ-treated (but not TNFi-treated) UC patients, lymphoid aggregate (LA) size was significantly reduced in treatment responders compared to non-responders (defined by absence of histological inflammation). A distinct validation cohort further confirmed that reduced lymphoid aggregate size was associated with response to VDZ-therapy (Fig 1D). Conclusion VDZ is associated with impaired ingress of naïve B and T cells, resulting in attrition of intestinal LA. Reduced LA size is associated with VDZ response. Immune inductive site targeting represents a novel MOA of VDZ in patients with UC.

Early treatment with anti-α4β7 antibody facilitates increased gut macrophage maturity in SIV-infected rhesus macaques.

Despite advances in combination antiretroviral therapy (cART), people living with HIV (PLWH) continue to experience gastrointestinal dysfunction. Infusions of anti-α4β7 monoclonal antibodies (mAbs) have been proposed to increase virologic control during simian immunodeficiency virus (SIV) infection in macaques with mixed results. Recent evidences suggested that therapeutic efficacy of vedolizumab (a humanized anti-α4β7 mAb), during inflammatory bowel diseases depends on microbiome composition, myeloid cell differentiation, and macrophage phenotype. We tested this hypothesis in SIV-infected, anti-α4β7 mAb-treated macaques and provide flow cytometric and microscopic evidence that anti-α4β7 administered to SIV-infected macaques increases the maturity of macrophage phenotypes typically lost in the small intestines during SIV disease progression. Further, this increase in mature macrophage phenotype was associated with tissue viral loads. These phenotypes were also associated with dysbiosis markers in the gut previously identified as predictors of HIV replication and immune activation in PLWH. These findings provide a novel model of anti-α4β7 efficacy offering new avenues for targeting pathogenic mucosal immune response during HIV/SIV infection.

HIV-1 acquisition in a man with ulcerative colitis on anti-α4β7 mAb vedolizumab treatment.

HIV-1 acquisition in a man with ulcerative colitis on anti-α4β7 mAb vedolizumab treatment.

Safety and Immunological Evaluation of Interleukin-21 Plus Anti-α4β7 mAb Combination Therapy in Rhesus Macaques.

Human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) infections compromise gut immunological barriers, inducing high levels of inflammation and a severe depletion of intestinal CD4+ T cells. Expression of α4β7 integrin promotes homing of activated T cells to intestinal sites where they become preferentially infected; blockade of α4β7 with an anti-α4β7 monoclonal antibody (mAb) prior to infection has been reported to reduce gut SIV viremia in rhesus macaques (RMs). Interleukin-21 (IL-21) administration in antiretroviral therapy-treated, SIV-infected RMs reduces gut inflammation and improves gut integrity. We therefore hypothesized that the combination of IL-21 and anti-α4β7 mAb therapies could synergize to reduce inflammation and HIV persistence. We co-administered two intravenous doses of rhesus anti-α4β7 mAb (50 mg/kg) combined with seven weekly subcutaneous infusions of IL-21–IgFc (100 μg/kg) in four healthy, SIV-uninfected RMs to evaluate the safety and immunological profiles of this intervention in blood and gut. Co-administration of IL-21 and anti-α4β7 mAb showed no toxicity at the given dosages as assessed by multiple hematological and chemical parameters and did not alter the bioavailability of the therapeutics or result in the generation of antibodies against the anti-α4β7 mAb or IL-21–IgFc. Upon treatment, the frequency of CD4 memory T cells expressing β7 increased in blood and decreased in gut, consistent with an inhibition of activated CD4 T-cell homing to the gut. Furthermore, the frequency of T cells expressing proliferation and immune activation markers decreased in blood and, more profoundly, in gut. The combined IL-21 plus anti-α4β7 mAb therapy is well-tolerated in SIV-uninfected RMs and reduces the gut homing of α4β7+ CD4 T cells as well as the levels of gut immune activation.

Delayed vaginal SHIV infection in VRC01 and anti-α4β7 treated rhesus macaques.

VRC01 protects macaques from vaginal SHIV infection after a single high-dose challenge. Infusion of a simianized anti-α4β7 mAb (Rh-α4β7) just prior to, and during repeated vaginal exposures to SIVmac251 partially protected macaques from vaginal SIV infection and rescued CD4+ T cells. To investigate the impact of combining VRC01 and Rh-α4β7 on SHIV infection, 3 groups of macaques were treated with a suboptimal dosing of VRC01 alone or in combination with Rh-α4β7 or with control antibodies prior to the initiation of weekly vaginal exposures to a high dose (1000 TCID50) of SHIVAD8-EO. The combination Rh-α4β7-VRC01 significantly delayed SHIVAD8-EO vaginal infection. Following infection, VRC01-Rh-α4β7-treated macaques maintained higher CD4+ T cell counts and exhibited lower rectal SIV-DNA loads compared to controls. Interestingly, VRC01-Rh-α4β7-treated macaques had fewer IL-17-producing cells in the blood and the gut during the acute phase of infection. Moreover, higher T cell responses to the V2-loop of the SHIVAD8-EO envelope in the VRC01-Rh-α4β7 group inversely correlated with set point viremia. The combination of suboptimal amounts of VRC01 and Rh-α4β7 delayed infection, altered antiviral immune responses and minimized CD4+ T cell loss. Further exploration of the effect of combining bNAbs with Rh-α4β7 on SIV/HIV infection and antiviral immune responses is warranted and may lead to novel preventive and therapeutic strategies.

Integrin α4β7 Blockade Preferentially Impacts CCR6+ Lymphocyte Subsets in Blood and Mucosal Tissues of Naive Rhesus Macaques.

Infusion of a simianized anti-α4β7 mAb (Rh-α4β7) just before and following SIV infection protected rhesus macaques from developing AIDS and partially from vaginal SIV acquisition. Recently, short-term treatment with Rh-α4β7 in combination with cART was found to lead to prolonged viral suppression after withdrawal of all therapeutic interventions. The humanized form of Rh-α4β7, vedolizumab, is a highly effective treatment for inflammatory bowel disease. To clarify the mechanism of action of Rh-α4β7, naive macaques were infused with Rh-α4β7 and sampled in blood and tissues before and after treatment to monitor several immune cell subsets. In blood, Rh-α4β7 increased the CD4+ and CD8+ T cell counts, but not B cell counts, and preferentially increased CCR6+ subsets while decreasing CD103+ and CD69+ lymphocytes. In mucosal tissues, surprisingly, Rh-α4β7 did not impact integrin α4+ cells, but decreased the frequencies of CCR6+ and CD69+ CD4+ T cells and, in the gut, Rh-α4β7 transiently decreased the frequency of memory and IgA+ B cells. In summary, even in the absence of inflammation, Rh-α4β7 impacted selected immune cell subsets in different tissues. These data provide new insights into the mechanisms by which Rh-α4β7 may mediate its effect in SIV-infected macaques with implications for understanding the effect of treatment with vedolizumab in patients with inflammatory bowel disease.

47 Immuno-PET/CT imaging reveals differences in virus and CD4+ cell localization in SIV infected rhesus macaques treated with an anti-α4β7 mab

47 Immuno-PET/CT imaging reveals differences in virus and CD4+ cell localization in SIV infected rhesus macaques treated with an anti-α4β7 mab

A Small Molecule, Which Competes with MAdCAM-1, Activates Integrin α4β7 and Fails to Prevent Mucosal Transmission of SHIV-SF162P3.

Mucosal HIV-1 transmission is inefficient. However, certain viral and host characteristics may play a role in facilitating HIV acquisition and systemic expansion. Cells expressing high levels of integrin α4β7 have been implicated in favoring the transmission process and the infusion of an anti-α4β7 mAb (RM-Act-1) prior to, and during a repeated low-dose vaginal challenge (RLDC) regimen with SIVmac251 reduced SIV acquisition and protected the gut-associated lymphoid tissues (GALT) in the macaques that acquired SIV. α4β7 expression is required for lymphocyte trafficking to the gut lamina propria and gut inductive sites. Several therapeutic strategies that target α4β7 have been shown to be effective in treating inflammatory conditions of the intestine, such as inflammatory bowel disease (IBD). To determine if blocking α4β7 with ELN, an orally available anti-α4 small molecule, would inhibit SHIV-SF162P3 acquisition, we tested its ability to block MAdCAM-1 (α4β7 natural ligand) and HIV-gp120 binding in vitro. We studied the pharmacokinetic profile of ELN after oral and vaginal delivery in macaques. Twenty-six macaques were divided into 3 groups: 9 animals were treated with ELN orally, 9 orally and vaginally and 8 were used as controls. All animals were challenged intra-vaginally with SHIV-SF162P3 using the RLDC regimen. We found that ELN did not protect macaques from SHIV acquisition although it reduced the SHIV-induced inflammatory status during the acute phase of infection. Notably, integrins can exist in different activation states and, comparing the effect of ELN and the anti-α4β7 mAb RM-Act-1 that reduced susceptibility to SIV infection, we determined that ELN induces the active conformation of α4β7, while RM-Act-1 inhibits its activation through an allosteric mechanism. These results suggest that inhibition of α4β7 activation may be necessary to reduce susceptibility to SIV/SHIV infection and highlight the complexity of anti-integrins therapeutic approach in HIV as well as in IBD and other autoimmune diseases.

Anti-α4β7 mAb prevents MAdCAM-1-mediated activation and HIV replication in CD4+ T cells

Abstract HIV-1 preferentially infects α4β7+ CD4+ T cells, causing irreversible depletion of these cells in gut-associated lymphoid tissue (GALT) during the acute phase of infection. α4β7 mediates homing of CD4+ T cells to GALT through an interaction with mucosal addressin cell adhesion molecule-1 (MAdCAM-1), expressed on gut endothelial venules. In a rhesus macaque model of HIV transmission, administration of an anti-α4β7 mAb protected GALT from SIV infection. The mechanism(s) underlying this protection are poorly understood. We hypothesized that the anti-α4β7 mAb prevents MAdCAM mediated co-stimulation in a manner that could contribute to the protection that we observed. We determined that costimulation of CD4+ T cells through MAdCAM could support both proliferation of CD4+ T cells and viral replication in a manner that was inhibited by the anti-α4β7 mAb. In addition, MAdCAM costimulation induced the up-regulation of Ki-67, CD38 and CXCR5. Interestingly, we found that MAdCAM could induce the expression of CD45RO on naïve CD4+ T cells in the absence of proliferation, suggesting that this mode of costimulation is unique. These results indicate that costimulation of CD4+ T cells via MAdCAM provides a signal that promotes replication of HIV. Moreover, an anti-α4β7 mAb that interferes with the binding of MAdCAM to α4β7 inhibits both proliferation and viral replication, providing a potential mechanism for the capacity of this mAb to protect rhesus macaques from infection by SIV.

Evaluation of a newly developed assay designed to assess the interaction between α4β7 and MAdCAM

Abstract HIV infection is characterized by high-level replication in gut-associated lymphoid tissues (GALT). This occurs in part because α4β7 +/CD4+ T cells are a preferred target of HIV infection. α4β7 functions as a gut homing receptor. Homing is mediated through a specific interaction with MAdCAM that is expressed on the surface of the high-endothelial venules that line the gut. In addition, α4β7 binds to the V2 domain of HIV gp120. In an SIV model of HIV mucosal transmission, an antibody specific for α4β7 +was found to prevent infection, but the underlying mechanism for this protection is not fully understood. We have proposed that signaling through α4β7 + facilitates HIV transmission, and that the protection from infection that we observed may reflect the capacity of the anti-α4β7 mAb we employed to interfere with this signaling. In order to investigate the role of α4β7+ signaling in mucosal transmission, we have employed a newly developed adhesion assay (Peachman and Rao) that measures the interaction between either the V2 domain of HIV gp120 or MAdCAM with cells expressing α4β7. We have used this assay to evaluate small molecules and antibody antagonists of these interactions. We have found that small molecule antagonists that bind to the active site in α4β7 abrogate binding of cells to both MAdCAM and the V2 domain of HIV gp120. In addition, we determined that retinoic acid increases the adhesion of MAdCAM and V2 to α4β7 expressing cells. This assay should aid in the development of novel strategies designed to interfere with the trafficking of α4β7 +cells to GALT and to mucosal transmission of HIV.