Lymphocyte Homing Research Articles

More Levels of Complexity in the Control of Intestinal Inflammation

More Levels of Complexity in the Control of Intestinal Inflammation

CXC Chemokine Receptor Type 5 Gene Polymorphisms in a Cohort of Egyptian Patients with Diffuse Large B-Cell Lymphoma

Background: The chemokine receptor CXCR5 is selectively expressed on B cells; it is involved in lymphocyte homing and the development of normal lymphoid tissue. Its principle ligand is CXCL13 or B lymphocyte chemoattractant. Three polymorphisms in the CXCR5 gene, rs148351692 C/G, rs6421571 C/T, and rs78440425 G/A, have been identified. Objective: To assess the genetic polymorphisms of CXCR5 and evaluate their possible contribution to the susceptibility and response to therapy of diffuse large B-cell lymphoma (DLBCL). Patients and Methods: Fifty DLBCL (not otherwise specified) patients and 50 control subjects were included in this study. CXCR5 genotypes were determined by PCR-RFLP. Results: Our study revealed that the CXCR5 rs148351692 C/G and rs6421571 C/T gene polymorphisms are associated with an increased risk of developing DLBCL (OR 28.57 [95% CI 8.96–96.56] and 3.45 [1.67–11.83] respectively), while CXCR5 rs78440425 G/A showed no association with the risk of lymphoma. Moreover, the double and triple combined gene polymorphisms are associated with an increased risk of developing DLBCL of approximately 120-fold and 105-fold, respectively. CXCR5 gene polymorphisms had no significant impact on disease outcome or response to therapy. Conclusions: CXCR5 gene polymorphisms could be considered a potential risk factor for the development of DLBCL.

Mechanism and intervention of mucosal immune regulation based on "lung and large intestine being interior-exteriorly related" theory of traditional Chinese medicine

The "lung and large intestine being interior-exteriorly related" is one of the classical theories in traditional Chinese medicine, which indicates a close correlation between the lung and large intestine in physiology and pathology, and plays a pivotal role in guiding the treatment of the lung and bowel diseases. Modern medicine has revealed some connections between the lung and large intestine in tissue origin and mucosal immunity, and preliminarily illuminated the material basis and possible regulatory mechanism of the theory. Recently, this theory has been applied to guide the treatment of refractory lung and intestine diseases such as COVID-19 and ulcerative colitis and has obtained reliable efficacy. Existing research results show that the anatomical homogeneity of lung and large intestine promotes the correlation between lung-bowel mucosal immunity, and mucosal immunity and migration and homing of innate lymphocytes are one of the physiological and pathological mechanisms for lung and large intestine to share. Under the guidance of this theory, Chinese medicines with heat-clearing and detoxifying or tonic effects are commonly used in the treatment of the lung and intestinal diseases by regulating lung-bowel mucosal immunity and they can be candidate drugs to treat lung/intestinal diseases simultaneously. However, the existing studies on immune regulation are mainly focused on the expression levels of sIgA and cytokines, as well as the changes in the number of immune cells such as innate lymphocytes and B lymphocytes. While the following aspects need further investigation: the airway/intestinal mucous hypersecretion, the functional changes of pulmonary and intestinal mucosal barrier immune cells, the dynamic process of lung/intestinal mucosal immune interaction, the intervention effect of local pulmonary/intestinal microecology, the correlation and biological basis between the heat-clearing and detoxifying effect and the tonic effect, and its regulation of pulmonary/intestinal mucosal immunity. In this paper, we try to analyze the internal relationship between lung and intestine related diseases from the point of view of the common mucosal immune system of lung and intestine, and summarize the characteristics and rules of traditional Chinese medicine compound and its active ingredients, which have regulatory effect on lung and intestine mucosal immune system, so as to further explain the theoretical connotation of "lung and large intestine being interior-exteriorly related" and provide reference for the research and development of drugs for related diseases.

Mucin-Like Domain of Mucosal Addressin Cell Adhesion Molecule-1 Facilitates Integrin α4β7-Mediated Cell Adhesion Through Electrostatic Repulsion.

The homing of lymphocytes from blood to gut-associated lymphoid tissue is regulated by interaction between integrin α4β7 with mucosal vascular addressin cell adhesion molecule 1 (MAdCAM-1) expressed on the endothelium of high endothelial venules (HEVs). However, the molecular basis of mucin-like domain, a specific structure of MAdCAM-1 regulating integrin α4β7-mediated cell adhesion remains obscure. In this study, we used heparan sulfate (HS), which is a highly acidic linear polysaccharide with a highly variable structure, to mimic the negative charges of the extracellular microenvironment and detected the adhesive behaviors of integrin α4β7 expressing 293T cells to immobilized MAdCAM-1 in vitro. The results showed that HS on the surface significantly promoted integrin α4β7-mediated cell adhesion, decreased the percentage of cells firmly bound and increased the rolling velocities at high wall shear stresses, which was dependent on the mucin-like domain of MAdCAM-1. Moreover, breaking the negative charges of the extracellular microenvironment of CHO-K1 cells expressing MAdCAM-1 with sialidase inhibited cell adhesion and rolling velocity of 293T cells. Mechanistically, electrostatic repulsion between mucin-like domain and negative charges of the extracellular microenvironment led to a more upright conformation of MAdCAM-1, which facilitates integrin α4β7-mediated cell adhesion. Our findings elucidated the important role of the mucin-like domain in regulating integrin α4β7-mediated cell adhesion, which could be applied to modulate lymphocyte homing to lymphoid tissues or inflammatory sites.

MAdCAM-1/α4β7 Integrin-Mediated Lymphocyte/Endothelium Interactions Exacerbate Acute Immune-Mediated Hepatitis in Mice.

Background & AimsAberrant lymphocyte homing could potentially link inflammatory processes in the intestine and the liver, as distinct hepatobiliary diseases frequently develop as extra-intestinal manifestations in inflammatory bowel disease. In this study, we examined the role of the gut-tropic leukocyte adhesion molecule β7 integrin and its endothelial ligand mucosal addressin cell-adhesion molecule-1 (MAdCAM-1) in immune-mediated hepatitis in mice.MethodsWild-type (WT) mice, MAdCAM-1-deficient mice, β7 integrin-deficient mice, RAG-2–deficient mice, RAG-2/MAdCAM-1 double-deficient mice, and RAG-2/β7 integrin double-deficient mice were subjected to concanavalin A (ConA)-induced hepatitis. The degree of hepatitis was evaluated by histology, flow cytometry, and expression analysis of inflammatory mediators. The motility of lymphocytes in progressive liver damage was assessed by intravital laser scanning multiphoton microscopy.ResultsAblation of MAdCAM-1 or β7 integrin ameliorated ConA-induced hepatitis in mice. β7 integrin-deficient lymphocytes caused less liver damage than WT lymphocytes in ConA-treated RAG-2–deficient mice. Moreover, WT lymphocytes caused less liver damage in ConA-treated RAG-2/β7 integrin double-deficient mice than in similarly treated RAG-2–deficient mice, indicating that β7 integrin expression contributes significantly to the liver damage mediated by innate immune cells. MAdCAM-1 expression was dependent on β7 integrin expression on adaptive and innate immune cells. Most importantly, lymphocytes in ConA-treated MAdCAM-1-deficient mice displayed more motility and less adhesion in the liver sinusoids in vivo, than lymphocytes in similarly treated WT mice.ConclusionsThese data suggest that β7 integrin expression on lymphocytes and innate immune cells contributes to MAdCAM-1 upregulation and liver damage in acute immune-mediated hepatitis, most likely by facilitating lymphocyte/sinusoidal endothelial cell interactions.

The adhesion molecule ICAM-1 in diffuse large B-cell lymphoma post-rituximab era: relationship with prognostic importance and rituximab resistance.

Intercellular adhesion molecule-1 (ICAM-1) is a cell-surface receptor contributing to lymphocyte homing, adhesion and activation. The prognostic significance of the protein is unknown in diffuse large B-cell lymphoma (DLBCL) in post-rituximab era. We detected expression of ICAM-1 immunohistochemically in 102 DLBCL tissue samples. Overexpression of ICAM-1 was found in 28 (27.5%) cases. In patients with low ICAM-1 expression levels, the addition of rituximab to CHOP (cyclophosphamide, doxorubicin, vincristine and prednisone) chemotherapy resulted in an improved overall response rate, progression-free survival (PFS) and overall survival (OS) (P=0.019, 0.01, 0.02). In pre-clinical models, we found that chronic exposure of cell lines to rituximab led to downregulation of ICAM-1 and acquirement of a rituximab resistant phenotype. In vitro exposure of rituximab resulted in rapid aggregation of B-cells regardless of the ICAM-1 expression levels. MTT assay showed knockdown of ICAM-1 could cause rituximab resistance. Neutralization of ICAM-1 did not affect rituximab activity in vitro and in vivo. Our data illustrated that in post-rituximab era, R-CHOP significantly improved the ORR, PFS and OS in ICAM-1 negative subset patients. Downregulation of ICAM-1 may contribute to rituximab resistance, and that rituximab, by promoting cell-cell aggregation, may sensitize cells to the cytotoxic effects of chemotherapy agents.

The Scaffolding Protein NEDD9 Regulates Chronic Lymphocytic Leukemia Cell Migration Via the CXCR4 - CXCL12 Axis and Promotes Disease Progression

Despite the undeniable vast improvement in CLL treatment strategies, resistance to novel compounds such as ibrutinib and venetoclax already emerged and posed a challenge in many aggressive cases. The fundamental role of the homing process in CLL progression and presumably relapse prompted us to analyze the impact of a crucial regulator of chemokine response, migration and lymphocyte homing - namely NEDD9 - on CLL pathogenesis. The scaffold protein NEDD9 is frequently upregulated and hyperphosphorylated in different cancer entities, with its deregulation being associated with poor clinical outcome and therapy resistance. In B cells, activation of integrin- and the B cell receptor signaling pathways leads to hyperphosphorylation of NEDD9, predominantly by Src family kinases, promoting cell adhesion, migration and chemotaxis. To elucidate the functional relevance of NEDD9 in CLL pathogenesis in vivo,Eµ-TCL1 transgenic mice were crossbred with Nedd9 deficient mice. CLL burden was monitored in the peripheral blood of Nedd9-proficient (TCL1tg/wt Nedd9wt/wt)versus Nedd9-deficient (TCL1tg/wt Nedd9-/-) mice every two months over a year, revealing a significantly lower proportion of CLL per total B cells (CLL/B cells) in the peripheral blood in TCL1tg/wt Nedd9-/- mice at four and six months of age. CLL onset was clearly delayed in TCL1tg/wt Nedd9-/- mice in comparison to TCL1tg/wt Nedd9wt/wt mice. The infiltration of CLL cells into the spleen and bone marrow was significantly reduced in TCL1tg/wt Nedd9-/- mice at three and ten months, accompanied by significantly longer overall survival of the TCL1tg/wt Nedd9-/- group. Particularly, this eminent role of Nedd9 in CLL pathogenesis could be largely attributed to Nedd9 expression in B cells. Using a conditional Nedd9 knockout mouse exclusively in B cells (TCL1tg/wt CD19Cretg/wt Nedd9flfl (TCN)), we observed a highly similar phenotype of TCN mice to the TCL1tg/wt Nedd9-/- mice, including significantly delayed CLL onset, lower proportion of CLL per total B cells (CLL/B cells) in the peripheral blood, and reduced hepatosplenomegaly in TCN mice compared to the control TCL1tg/wt CD19Crewt/wt Nedd9flfl (TN) mice. In summary, our mouse data suggest that Nedd9 deficiency significantly delayed CLL onset and progression, particularly in the early stages of CLL. Moreover, Nedd9 deficiency significantly decreased the accumulation of CLL cells both in typical leukemic homing organs such as spleen and bone marrow as well as in the peripheral blood in two independent mouse models and significantly prolonged survival of the TCL1tg/wt Nedd9-/- mice. The strongly reduced capacity of Nedd9-deficient CLL cells to migrate and home to the lymphoid niche prompted us to investigate the underlying mechanistic signaling pathway upon Nedd9 loss. For this purpose, we examined surface expression levels of prominent cell trafficking mediators on Nedd9-proficient and -deficient CLL cells, and found a consistently reduced level of CXCR4 on the surface of TCL1tg/wt Nedd9-/-cells. In the transwell assay, CLL cells isolated from TCL1tg/wt Nedd9-/- mice showed a dramatic reduction in migration towards CXCL12 compared to their wild type counter parts. In line with the results of the murine CLL cells, NEDD9-depleted MEC1 cells (shNedd9) also showed decreased CXCR4 levels and dramatic reduction in migration towards CXCL12 compared to the control cell line (shNT). Collectively, we provide the first direct evidence that genetic targeting of Nedd9 in vivo impairs CLL cell adhesion, migration and chemotaxis, resulting in decreased CLL cell infiltration into secondary lymphoid organs and the bone marrow. These observations could serve as basis for the development of new treatment strategies, targeting a scaffold protein to impair the homing process of CLL cells, a prerequisite for their survival and expansion within the microenvironment of protective niches. Disclosures No relevant conflicts of interest to declare.

Xeno-MCL: Genomic, Transcriptomic and Pathologic Landscape Associated with Disease Progression, Clonal Evolution and Tissue Tropism in Patient-Derived Xenografts of Mantle Cell Lymphoma

Mantle cell lymphoma (MCL) is an aggressive subtype of non-Hodgkin lymphoma with poor diagnosis. Frequent relapse to frontline therapies is one of the major medical challenges in MCL. This is likely due to the extremely complex inter- and intra-tumor heterogeneity (ITH) in MCL patients. MCL patients display diverse clinicopathological profiles and tissue dissemination patterns, which can involve both nodal and extra nodal sites, including splenomegaly, hepatomegaly, lymphadenopathy, and involvement of bone marrow (BM), gastrointestinal (GI) tract, peripheral blood (PB), and the central nervous system. To date, it has not been reported how tissue tropism of MCL cells contribute to ITH, disease progression, and clonal evolution. This cannot be easily addressed using primary patient samples without simultaneous or sequential sampling from diverse dissemination sites, which is largely not feasible, especially for those requiring invasive collection. To this end, we established patient-derived xenograft (PDX) models from primary patient samples and characterize them in this study. Due to the distinct microenvironment, orthotopic PDX models have been shown to be much better platforms for preclinical and mechanistic studies than heterotopic or subcutaneous PDX (PDX_sc) models. Therefore, we established multiple MCL PDX models via intravenous (PDX_iv) or intraosseous routes and characterized them for the first time on how they recapitulate the disease in MCL patients in comparison to subcutaneous models when available. These PDX_iv models were successfully passed onto serious generations (up to 10) through IV or SC via PDX cells from spleen of PDX_iv or PDX_sc tumor, respectively (Figure 1). To understand the recapitulation of ITH in PDX models and their contribution to disease progression and clonal evolution, we collected specimens from both disseminated PDX_iv and PDX_sc cells from serious generations and subject them to a multi-dimensional investigation, including pathological, transcriptomic, and genetic profiling (Figure 1). Consistent in MCL patients, we observed a high degree of histopathological heterogeneity across PDX models originating from different patients, including splenomegaly, hepatomegaly, lymphadenopathy, and involvement of BM, GI tract and/or PB in our PDX_iv models. These models displayed similar dissemination patterns across generations when checked at 2 months after intravenous cell implantation, while additional dissemination sites may be reached at late disease stages, such as the stomach, colon, kidney and uterus. To understand the disease progression and clonal evolution, we performed whole exome sequencing (WES) on 62 PDX samples collected across tissues and generations, primary patient samples used to establish the models (n=6), and their matched germline samples (n=6). Our data revealed a high degree of recapitulation of PDX_iv to patients and genetic inter-patient heterogeneity. Clonal evolution events were investigated for both PDX_iv and PDX_sc models. We demonstrated that PDX_iv models passed by PDX cells from the spleen are genetically more stable than PDX_sc models, in which more frequent chromosomal gain/loss and/or gene mutations occurred toward later generations. Mutations in certain genes such as SVEP1 and STAB1, which play important roles in lymphocyte homing, were found to associate with tissue tropism. To further address this, we performed single-cell RNA sequencing on 41 PDX samples collected across tissues and generations together with primary patient samples (n=8) and PBMC samples from healthy donors (n=2). Transcriptomic profiling showed that G1 PDX_iv models recapitulated primary patient samples very well, and along generations, further upregulation of cancer hallmarks was observed, indicating disease progression into more aggressive stages along generations and late disease stages. Again, PDX_sc models were more transcriptionally dysregulated across generations. Moreover, in vivo efficacy studies showed that PDX cells responded differently to drug treatments such as venetoclax and rituximab based on their homing sites. In conclusion, we addressed the tissue tropism, therapeutic response, clonal evolution in MCL PDX models at multi-dimensional platforms, for the first time, and comparing the mutagenesis and disease progression of orthotopic and heterotopic PDX models at an unprecedented resolution. Figure 1 Disclosures Wang: Lu Daopei Medical Group: Honoraria; Beijing Medical Award Foundation: Honoraria; OncLive: Honoraria; Molecular Templates: Research Funding; Verastem: Research Funding; Dava Oncology: Honoraria; Guidepoint Global: Consultancy; Nobel Insights: Consultancy; Oncternal: Consultancy, Research Funding; InnoCare: Consultancy; Acerta Pharma: Research Funding; VelosBio: Research Funding; BioInvent: Research Funding; Juno: Consultancy, Research Funding; Kite Pharma: Consultancy, Other: Travel, accommodation, expenses, Research Funding; Pulse Biosciences: Consultancy; Loxo Oncology: Consultancy, Research Funding; Targeted Oncology: Honoraria; OMI: Honoraria, Other: Travel, accommodation, expenses; Celgene: Consultancy, Other: Travel, accommodation, expenses, Research Funding; AstraZeneca: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding; Janssen: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding; MoreHealth: Consultancy; Pharmacyclics: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding.

Inhibition of CD44 attenuates pressure overload-induced cardiac and lung inflammation, fibrosis, and heart failure progression

Abstract Background Inflammation contributes to heart failure (HF) development and progression. CD44 is a member of the hyaluronate receptor family of cell adhesion molecules, which regulates tissue inflammation and fibrosis through modulating macrophage and lymphocyte migration and homing in several diseases. Here we evaluated the role and cellular mechanism of CD44 in regulating transverse aortic constriction (TAC)-induced HF development and progression in mice. Methods and results C57/B6 background CD44 KO and wild type mice (6–8 weeks) were subjected to TAC to evaluate the effect of CD44 on the development of TAC-induced LV hypertrophy and cardiac dysfunction. Due to the rapid response to TAC, Balb/c mice (6–8 weeks) were used to determine the effect of CD44 on the progression of TAC-induced congestive heart failure. We found that CD44 expression is dramatically increased in left ventricular (LV) tissues obtained from HF patients and mice. While CD44 gene knockout (KO) has no detectable effect on cardiac structure and function under control conditions, CD44 KO mice were protected from TAC-induced LV inflammation, fibrosis, hypertrophy, dysfunction, and lung remodeling as compared with wild type mice. In addition, we found that inhibition of CD44 signaling with blocking antibodies (Abs) significantly attenuated the transition from LV failure to lung remodeling, and right ventricular hypertrophy in mice with existing HF. Conclusions These data identify an important role of CD44 in attenuating cardiac and lung inflammation, fibrosis, HF development, and HF progression, suggesting that inhibition of CD44 signaling may be useful in preventing and treating HF. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Chinese National Natural Science Foundation Grants and American Heart Association

Lymphocyte homing: getting lymphocytes to the right place at the right time

Lymphocyte homing: getting lymphocytes to the right place at the right time

Activated melanoma vessels: A sticky point for successful immunotherapy.

Metastatic melanoma is a devastating disease with a marginal-albeit increasing-hope for cure. Melanoma has a high mutation rate which correlates to the expression of numerous neo-antigens and thus is associated with the potential to induce and strengthen effective antitumoral immunity. However, the incomplete and potentially insufficient response to established immunotherapies (response rates usually do not markedly exceed 60%) already points to the need of further studies to improve treatment strategies. Multiple tumor escape mechanisms that allow melanoma to evade from antitumoral immune responses have been characterized and must be overcome to achieve a better clinical efficacy of immunotherapies. Recently, promising progress has been made in targeting tumor vasculature to control and increase the infiltration of tumors with effector lymphocytes. It has been hypothesized that amplified lymphocytic infiltrates in melanoma metastases result in a switch of the tumor microenvironment from a non-inflammatory to an inflammatory state. In this view point essay, we discuss the requirements for successful homing of lymphocytes to melanoma tissue and we present a mouse melanoma xenograft model that allows the investigation of human tumor vessels in vivo. Furthermore, current clinical studies dealing with the activation of melanoma vasculature for enhanced effectiveness of immunotherapy protocols are presented and open questions for routine clinical application are addressed.

Carbohydrate Sulfotransferase 4 Inhibits the Progression of Hepatitis B Virus-Related Hepatocellular Carcinoma and Is a Potential Prognostic Marker in Several Tumors.

Carbohydrate sulfotransferase 4 (CHST4) plays an important role in lymphocyte homing and is abnormally expressed in several cancer types; however, its precise function in tumor development and progression is unknown. Here we confirm that CHST4 is aberrantly expressed in various tumor subtypes. In particular, we found that CHST4 expression was downregulated in hepatitis B virus-related hepatocellular carcinoma (HBV-HCC) tumors compared to paired normal tissue. We also showed that CHST4 overexpression inhibited the proliferation and metastasis of HCC cells in vitro. Clinically, CHST4 was identified as an independent prognostic factor for HBV-HCC patients. We further illuminated the anti-tumor role and mechanism of CHST4 in HBV-HCC by constructing a FENDRR–miR-10b-5p–CHST4 competing endogenous RNA network. We found that downregulation of CHST4 expression may promote HBV expression and regulate ribonucleoprotein complex biogenesis to promote malignant behaviors in HBV-HCC. CHST4 may also recruit CD4+ T cells, macrophages, dendritic cells, and neutrophils into the tumor microenvironment to inhibit the progression of HBV-HCC. Overall, our findings suggest that CHST4 acts as a tumor suppressor in HCC-HBV and represents a potential diagnostic and therapeutic target.

Severe Human Lassa Fever Is Characterized by Nonspecific T-Cell Activation and Lymphocyte Homing to Inflamed Tissues.

Lassa fever (LF) is a zoonotic viral hemorrhagic fever caused by Lassa virus (LASV), which is endemic to West African countries. Previous studies have suggested an important role for T-cell-mediated immunopathology in LF pathogenesis, but the mechanisms by which T cells influence disease severity and outcome are not well understood. Here, we present a multiparametric analysis of clinical immunology data collected during the 2017-2018 Lassa fever outbreak in Nigeria. During the acute phase of LF, we observed robust activation of the polyclonal T-cell repertoire, which included LASV-specific and antigenically unrelated T cells. However, severe and fatal LF cases were characterized by poor LASV-specific effector T-cell responses. Severe LF was also characterized by the presence of circulating T cells with homing capacity to inflamed tissues, including the gut mucosa. These findings in LF patients were recapitulated in a mouse model of LASV infection, in which mucosal exposure resulted in remarkably high lethality compared to skin exposure. Taken together, our findings indicate that poor LASV-specific T-cell responses and activation of nonspecific T cells with homing capacity to inflamed tissues are associated with severe LF.IMPORTANCE Lassa fever may cause severe disease in humans, in particular in areas of endemicity like Sierra Leone and Nigeria. Despite its public health importance, the pathophysiology of Lassa fever in humans is poorly understood. Here, we present clinical immunology data obtained in the field during the 2018 Lassa fever outbreak in Nigeria indicating that severe Lassa fever is associated with activation of T cells antigenically unrelated to Lassa virus and poor Lassa virus-specific effector T-cell responses. Mechanistically, we show that these bystander T cells express defined tissue homing signatures that suggest their recruitment to inflamed tissues and a putative role of these T cells in immunopathology. These findings open a window of opportunity to consider T-cell targeting as a potential postexposure therapeutic strategy against severe Lassa fever, a hypothesis that could be tested in relevant animal models, such as nonhuman primates.

Circulating α4β7+ Memory T Cells in Pediatric IBD Patients Express a Polyclonal T Cell Receptor Repertoire.

BackgroundThe integrin α4β7 is highly expressed on activated T cells and is thought to direct homing of lymphocytes to the intestine. Since ulcerative colitis (UC) and Crohn’s disease (CD) are characterized by mucosal oligoclonal T cells’ expansion, we aimed to assess whether similar repertoire features are identified in circulating gut-specific memory T cells.MethodsMemory CD3+ T cells were isolated from blood samples of control subjects and patients with active UC or CD and then FACS-sorted into α4β7+ and α4β7− populations. DNA was extracted from each subset and subjected to next-generation sequencing of the TCRβ. Different repertoire characteristics were compared between α4β7+ and α4β7− subsets for each subject, and between groups.ResultsThe percentages of memory T cells and α4β7+ cells were comparable between groups. α4β7+ memory T cells displayed a polyclonal distribution, in control subjects and in UC or CD patients, with similar indices of diversity. Strikingly, the clonal overlap between α4β7+ and α4β7− T cells for each subject in all three groups was high, ranging between 20%–50%. We were unable to identify shared T cell clones that were specific to one of the groups.Conclusionα4β7+ memory T cells exhibited a polyclonal repertoire in both control subjects and patients with active inflammatory bowel disease, with high rates of overlap with α4β7− memory T cells. Our study, along with additional recent reports, may suggest that the suppression of intestinal inflammation by vedolizumab is independent of the drug’s effect on T cell migration to the gut.

Dissecting Common and Unique Effects of Anti-α4β7 and Anti-Tumor Necrosis Factor Treatment in Ulcerative Colitis.

Background and AimsVedolizumab is an anti-α4β7 antibody approved for the treatment of ulcerative colitis [UC]. Although it is assumed that vedolizumab blocks intestinal homing of lymphocytes, its effects on different intestinal cell populations are not fully stablished. In order to establish the unique mechanisms of action of vedolizumab in UC patients, we compared its effects to those induced by anti-tumour necrosis factor [TNF].MethodsPatients with active UC [endoscopic Mayo score >1] starting vedolizumab [n = 33] or anti-TNF [n = 45] and controls [n = 22] were included. Colon biopsies [at weeks 0, 14 and 46] and blood samples [at weeks 0, 2, 6, 14, 30 and 46] were used for cell phenotyping, transcriptional analysis [qPCR], and to measure receptor occupancy.ResultsVedolizumab, in contrast to anti-TNF, significantly reduced the proportion of α4β7+ cells within intestinal T subsets while preserving the percentage of α4β7+ plasma cells. The marked decrease in α4β7 did not change the percentage of colonic αEβ7+ cells [at 46 weeks]. Both vedolizumab and anti-TNF significantly downregulated inflammation-related genes in the colon of responders [Mayo score < 2]. Moreover, both treatments significantly decreased the percentage of intestinal, but not blood, total lymphocytes [T and plasma cells], as well as the proportion of α4β1+ cells within intestinal T lymphocytes.ConclusionsOur data show that while vedolizumab and anti-TNF block two unrelated targets, they induce remarkably similar effects. On the other hand, vedolizumab’s unique mechanism of action relies on blocking intestinal trafficking of α4β7 T cells, despite effectively binding to B and plasma cells that express α4β7.

Cosmc controls B cell homing

The molecular mechanisms regulating lymphocyte homing into lymph nodes are only partly understood. Here, we report that B cell-specific deletion of the X-linked gene, Cosmc, and the consequent decrease of protein O-glycosylation, induces developmental blocks of mouse B cells. After transfer into wild-type recipient, Cosmc-null B cells fail to home to lymph nodes as well as non-lymphoid organs. Enzymatic desialylation of wild-type B cells blocks their migration into lymph nodes, indicating a requirement of sialylated O-glycans for proper trafficking. Mechanistically, Cosmc-deficient B cells have normal rolling and firm arrest on high endothelium venules (HEV), thereby attributing their inefficient trafficking to alterations in the subsequent transendothelial migration step. Finally, Cosmc-null B cells have defective chemokine signaling responses. Our results thus demonstrate that Cosmc and its effects on O-glycosylation are important for controlling B cell homing.

The Impact of Small Extracellular Vesicles on Lymphoblast Trafficking across the Blood-Cerebrospinal Fluid Barrier In Vitro.

Central nervous System (CNS) disease in pediatric acute lymphoblastic leukemia (ALL) is a major concern, but still, cellular mechanisms of CNS infiltration are elusive. The choroid plexus (CP) is a potential entry site, and, to some extent, invasion resembles CNS homing of lymphocytes during healthy state. Given exosomes may precondition target tissue, the present work aims to investigate if leukemia-derived exosomes contribute to a permissive phenotype of the blood-cerebrospinal fluid barrier (BCSFB). Leukemia-derived exosomes were isolated by ultracentrifugation from the cell lines SD-1, Nalm-6, and P12-Ichikawa (P12). Adhesion and uptake to CP epithelial cells and the significance on subsequent ALL transmigration across the barrier was studied in a human BCSFB in vitro model based on the HiBCPP cell line. The various cell lines markedly differed regarding exosome uptake to HiBCPP and biological significance. SD-1-derived exosomes associated to target cells unspecifically without detectable cellular effects. Whereas Nalm-6 and P12-derived exosomes incorporated by dynamin-dependent endocytosis, uptake in the latter could be diminished by integrin blocking. In addition, only P12-derived exosomes led to facilitated transmigration of the parental leukemia cells. In conclusion, we provide evidence that, to a varying extent, leukemia-derived exosomes may facilitate CNS invasion of ALL across the BCSFB without destruction of the barrier integrity.

CCL26 regulates the proportion of CD4+CD25+FOXP3+ Tregs and the production of inflammatory factors in peripheral blood mononuclear cells following acute ischemic stroke via the STAT5 pathway.

Acute ischemic stroke (AIS) is the most common type of stroke. Recent studies have found that AIS is closely involved in the immune regulation function of regulatory T cells (Tregs). C-C motif chemokine ligand 26 (CCL26) is a member of the chemokine family that plays an essential role in cell activation, cell differentiation, lymphocyte homing, and inflammatory and immune responses. The present study aimed to investigate the role of CCL26 in the regulation of Tregs in AIS. Peripheral blood mononuclear cells (PBMCs) were incubated with a CCL26-neutralizing antibody. The proportion of cluster of differentiation (CD)4+CD25+ forkhead box P3 (FOXP3)+ Tregs was increased, and the expression of FOXP3, phosphorylated signal transducer and activator of transcription 5 (p-STAT5), and that of the immunosuppressive factors, interleukin (IL)-10 and transforming growth factor (TGF)-β1, was upregulated. Conversely, the expression of immune-promoting factors, such as tumor necrosis factor (TNF)-α and IL-6 was significantly downregulated. Further experiments using CCL26 recombinant protein-treated PBMCs revealed a decreased proportion of CD4+CD25+FOXP3+ Tregs and the downregulated expression of FOXP3, p-STAT5, TGF-β1 and IL-10. Moreover, the expression of immunostimulatory factors, such as CX3C chemokine receptor 1, TNF-α and IL-6 was significantly upregulated. On the whole, these results demonstrate that CCL26 regulates the proportion of CD4+CD25+FOXP3+ Tregs and the production of inflammatory factors in PBMCs following AIS via the STAT5 pathway.

Fingolimod as a Treatment in Neurologic Disorders Beyond Multiple Sclerosis.

Fingolimod is an approved treatment for relapsing–remitting multiple sclerosis (MS), and its properties in different pathways have raised interest in therapy research for other neurodegenerative diseases. Fingolimod is an agonist of sphingosine-1-phosphate (S1P) receptors. Its main pharmacologic effect is immunomodulation by lymphocyte homing, thereby reducing the numbers of T and B cells in circulation. Because of the ubiquitous expression of S1P receptors, other effects have also been described. Here, we review preclinical experiments evaluating the effects of treatment with fingolimod in neurodegenerative diseases other than MS, such as Alzheimer’s disease or epilepsy. Fingolimod has shown neuroprotective effects in different animal models of neurodegenerative diseases, summarized here, correlating with increased brain-derived neurotrophic factor and improved disease phenotype (cognition and/or motor abilities). As expected, treatment also induced reductions in different neuroinflammatory markers because of not only inhibition of lymphocytes but also direct effects on astrocytes and microglia. Furthermore, fingolimod treatment exhibited additional effects for specific neurodegenerative disorders, such as reduction of amyloid-β production, and antiepileptogenic properties. The neuroprotective effects exerted by fingolimod in these preclinical studies are reviewed and support the translation of fingolimod into clinical trials as treatment in neurodegenerative diseases beyond neuroinflammatory conditions (MS).

Influence of HIV-1 V2 sequence variability on bacterial translocation in antiretroviral naïve HIV-1 infected patients.

HIV-1 V2 domain binds α4β7, which assists lymphocyte homing to gut-associated lymphoid tissue. This triggers bacterial translocation, thus contributing to immune activation. We investigated whether variability of V2 179-181 binding site could influence plasma levels of lipopolysaccharide (LPS) and soluble cluster of differentiation 14 (sCD14), markers of microbial translocation/immune activation. HIV gp120 sequences from antiretroviral naïve patients were analyzed for V2 tripeptide composition, length, net charge, and potential N-linked-glycosylation sites. LPS and sCD14 plasma levels were quantified. Clinical/immuno-virologic data were retrieved. Overall, 174 subjects were enrolled, 8% with acute infection, 71% harboring a subtype B. LDV179-181 was detected in 41% and LDI in 27%. No difference was observed between levels of LPS or sCD14 according to different mimotopes or according to other sequence characteristics. By multivariable analysis, only acute infection was significantly associated with higher sCD14 levels. In conclusion, no association was observed between V2 tripeptide composition and extent of bacterial translocation/immune activation.