Integrin LFA-1 Research Articles

The autophagy component LC3 regulates lymphocyte adhesion via LFA1 transport in response to outside-in signaling

The leukocyte integrin LFA1 is indispensable for immune responses, orchestrating lymphocyte trafficking and adhesion. While LFA1 activation induces LFA1 clustering at the cell contact surface via outside-in signaling, the regulatory mechanisms remain unclear. Here, we uncovered a previously hidden function of the autophagosome component LC3 beyond its role in autophagy by bridging two seemingly unrelated pathways: LFA1 transport and autophagosome transport. LFA1 clusters co-trafficked with LC3, facilitating LFA1 accumulation at the contact surface. LC3b knockout decreased lymphocyte adhesiveness. LFA1 activation did not induce autophagy, whereas it increased mTOR and AMPK activity. LFA1-dependent AMPK activation enhances LFA1 and LC3 clustering and adhesion. Inhibiting Mst1 kinase-mediated LC3 phosphorylation promoted LC3-mediated LFA1 recruitment to the contact surface through direct interaction with RAPL, uncovering an unprecedented integrin recruitment route. These findings uncover a function of LC3 and expand our understanding of lymphocyte regulation via LFA1.

RNAi library screening reveals Gβ1, Casein Kinase 2 and ICAP-1 as novel regulators of LFA-1-mediated T cell polarity and migration.

The αLβ2 integrin LFA-1 plays a key role in T-cell adhesion to the endothelial vasculature and migration into both secondary lymphoid organs and peripheral tissues via interactions with its target protein ICAM-1, but the pathways that regulate LFA-1-mediated T-cell polarity and migration are not fully understood. In this study we screened two RNAi libraries targeting G protein-coupled receptors (GPCR)/GPCR-associated proteins and kinases in a HuT 78 T cell line model of LFA-1-stimulated T-cell migration. Based on staining of the actin cytoskeleton, multiple parameters to measure cell morphology were used to assess the contribution of 1109 genes to LFA-1-mediated T-cell polarity and migration. These RNAi screens identified a number of both novel and previously identified genes that either increased or decreased the polarity and migratory capacity of these cells. Following multiparametric analysis, hierarchical clustering and pathway analysis, three of these genes were characterized in further detail using primary human T cells, revealing novel roles for the heterotrimeric G protein subunit Gβ1 and Casein Kinase 2 in LFA-1-mediated T-cell polarity and migration in vitro. Our studies also highlighted a new role for ICAP-1, an adaptor protein previously described to be associated with β1 integrins, in β2 integrin LFA-1-directed migration in T cells. Knockdown of ICAP-1 expression in primary T cells revealed a role in cell polarity, cell velocity and transmigration towards SDF-1 for this adaptor protein. This study therefore uncovers new roles for GPCR/GPCR-associated proteins and kinases in T-cell migration and provides potential novel targets for modulation of the T-cell immune response.

The eATP/P2×7R Axis Drives Quantum Dot-Nanoparticle Induced Neutrophil Recruitment in the Pulmonary Microcirculation.

Exposure to nanoparticles (NPs) is frequently associated with adverse cardiovascular effects. In contrast, NPs in nanomedicine hold great promise for precise lung-specific drug delivery, especially considering the extensive pulmonary capillary network that facilitates interactions with bloodstream-suspended particles. Therefore, exact knowledge about effects of engineered NPs within the pulmonary microcirculation are instrumental for future application of this technology in patients. To unravel the real-time dynamics of intravenously delivered NPs and their effects in the pulmonary microvasculature, we employed intravital microscopy of the mouse lung. Only PEG-amine-QDs, but not carboxyl-QDs triggered rapid neutrophil recruitment in microvessels and their subsequent recruitment to the alveolar space and was linked to cellular degranulation, TNF-α, and DAMP release into the circulation, particularly eATP. Stimulation of the ATP-gated receptor P2X7R induced expression of E-selectin on microvascular endothelium thereby mediating the neutrophilic immune response. Leukocyte integrins LFA-1 and MAC-1 facilitated adhesion and decelerated neutrophil crawling on the vascular surface. In summary, this study unravels the complex cascade of neutrophil recruitment during NP-induced sterile inflammation. Thereby we demonstrate novel adverse effects for NPs in the pulmonary microcirculation and provide critical insights for optimizing NP-based drug delivery and therapeutic intervention strategies, to ensure their efficacy and safety in clinical applications.

Chronic stimulation desensitizes β2-adrenergic receptor responses in natural killer cells.

Adrenergic receptors (ARs) are preferentially expressed by innate lymphocytes such as natural killer (NK) cells. Here, we study the effect of epinephrine-mediated stimulation of the β2-adrenergic receptor (β2AR) on the function of human NK cells. Epinephrine stimulation inhibited early NK cell signaling events and blocked the function of the integrin LFA-1. This reduced the adhesion of NK cells to ICAM-1, explaining how NK cells are mobilized into the peripheral blood upon epinephrine release during acute stress or exercise. Additionally, epinephrine stimulation transiently reduced NK cell degranulation, serial killing, and cytokine production and affected metabolic changes upon NK cell activation via the cAMP-protein kinase A (PKA) pathway. Repeated exposure to β2AR agonists resulted in the desensitization of the β2AR via a PKA feedback loop-initiated G-protein switch. Therefore, acute epinephrine stimulation of chronically β2AR stimulated NK cells no longer resulted in inhibited signaling and reduced LFA-1 activity. Sustained stimulation by long-acting β2-agonists (LABA) not only inhibited NK cell functions but also resulted in desensitization of the β2AR. However, peripheral NK cells from LABA-treated asthma patients still reacted unchanged to epinephrine stimulation, demonstrating that local LABA administration does not result in detectable systemic effects on NK cells.

NK cells with adhesion defects and reduced cytotoxic functions are associated with a poor prognosis in multiple myeloma

AbstractThe promising results obtained with immunotherapeutic approaches for multiple myeloma (MM) call for a better stratification of patients based on immune components. The most pressing being cytotoxic lymphocytes such as natural killer (NK) cells that are mandatory for MM surveillance and therapy. Here, we performed a single-cell RNA sequencing analysis of NK cells from 10 patients with MM and 10 age/sex–matched healthy donors that revealed important transcriptomic changes in the NK cell landscape affecting both the bone marrow (BM) and peripheral blood compartment. The frequency of mature cytotoxic CD56dim NK cell subsets was reduced in patients with MM at the advantage of late-stage NK cell subsets expressing NF-κB and interferon-I inflammatory signatures. These NK cell subsets accumulating in patients with MM were characterized by low CD16 and CD226 expression and poor cytotoxic functions. MM CD16/CD226Lo NK cells also had adhesion defects with reduced lymphocyte function-associated antigen 1 (LFA-1) integrin activation and actin polymerization that may account for their limited effector functions in vitro. Finally, analysis of BM-infiltrating NK cells in a retrospective cohort of 177 patients with MM from the Intergroupe Francophone du Myélome (IFM) 2009 trial demonstrated that a high frequency of NK cells and their low CD16 and CD226 expression were associated with a shorter overall survival. Thus, CD16/CD226Lo NK cells with reduced effector functions accumulate along MM development and negatively affect patients’ clinical outcomes. Given the growing interest in harnessing NK cells to treat myeloma, this improved knowledge around MM–associated NK cell dysfunction will stimulate the development of more efficient immunotherapeutic drugs against MM.

The LPS-inactivating enzyme acyloxyacyl hydrolase protects the brain from experimental stroke

Blood-brain-barrier (BBB) disruption is a pathological hallmark of ischemic stroke, and inflammation occurring at the BBB contributes to the pathogenesis of ischemic brain injury. Lipopolysaccharide (LPS), a cell wall component of Gram-negative bacteria, is elevated in patients with acute stroke. The activity of LPS is controlled by acyloxyacyl hydrolase (AOAH), a host enzyme that deacylates LPS to inactivated forms. However, whether AOAH influences the pathogenesis of ischemic stroke remain elusive. We performed in vivo experiments to explore the role and mechanism of AOAH on neutrophil extravasation, BBB disruption, and brain infarction. We found that AOAH was upregulated in neutrophils in peri-infarct areas from mice with transient focal cerebral ischemia. AOAH deficiency increased neutrophil extravasation into the brain parenchyma and proinflammatory cytokine production, broke down the BBB and worsened stroke outcomes in mice. These effects require Toll-like receptor 4 (TLR4) because absence of TLR4 or pharmacologic inhibition of TLR4 signaling prevented the exacerbated inflammation and BBB damage in Aoah−/− mice after ischemic stroke. Importantly, neutrophil depletion or inhibition of neutrophil trafficking by blocking LFA-1 integrin dramatically reduced stroke-induced BBB breakdown in Aoah−/− mice. Furthermore, virus-mediated overexpression of AOAH induced a substantial decrease in neutrophil recruitment that was accompanied by reducing BBB damage and stroke volumes. Our findings show the importance of AOAH in regulating neutrophil-dependent BBB breakdown and cerebral infarction. Consequently, strategies that modulate AOAH may be a new therapeutic approach for treatment of ischemic stroke.

Piezo1 mechanosensing regulates integrin-dependent chemotactic migration in human T cells.

T cells are crucial for efficient antigen-specific immune responses and thus their migration within the body, to inflamed tissues from circulating blood or to secondary lymphoid organs, plays a very critical role. T cell extravasation in inflamed tissues depends on chemotactic cues and interaction between endothelial adhesion molecules and cellular integrins. A migrating T cell is expected to sense diverse external and membrane-intrinsic mechano-physical cues, but molecular mechanisms of such mechanosensing in cell migration are not established. We explored if the professional mechanosensor Piezo1 plays any role during integrin-dependent chemotaxis of human T cells. We found that deficiency of Piezo1 in human T cells interfered with integrin-dependent cellular motility on ICAM-1-coated surface. Piezo1 recruitment at the leading edge of moving T cells is dependent on and follows focal adhesion formation at the leading edge and local increase in membrane tension upon chemokine receptor activation. Piezo1 recruitment and activation, followed by calcium influx and calpain activation, in turn, are crucial for the integrin LFA1 (CD11a/CD18) recruitment at the leading edge of the chemotactic human T cells. Thus, we find that Piezo1 activation in response to local mechanical cues constitutes a membrane-intrinsic component of the 'outside-in' signaling in human T cells, migrating in response to chemokines, that mediates integrin recruitment to the leading edge.

Piezo1 mechanosensing regulates integrin-dependent chemotactic migration in human T cells

T cells are crucial for efficient antigen-specific immune responses and thus their migration within the body, to inflamed tissues from circulating blood or to secondary lymphoid organs, plays a very critical role. T cell extravasation in inflamed tissues depends on chemotactic cues and interaction between endothelial adhesion molecules and cellular integrins. A migrating T cell is expected to sense diverse external and membrane-intrinsic mechano-physical cues, but molecular mechanisms of such mechanosensing in cell migration are not established. We explored if the professional mechanosensor Piezo1 plays any role during integrin-dependent chemotaxis of human T cells. We found that deficiency of Piezo1 in human T cells interfered with integrin-dependent cellular motility on ICAM-1-coated surface. Piezo1 recruitment at the leading edge of moving T cells is dependent on and follows focal adhesion formation at the leading edge and local increase in membrane tension upon chemokine receptor activation. Piezo1 recruitment and activation, followed by calcium influx and calpain activation, in turn, are crucial for the integrin LFA1 (CD11a/CD18) recruitment at the leading edge of the chemotactic human T cells. Thus, we find that Piezo1 activation in response to local mechanical cues constitutes a membrane-intrinsic component of the ‘outside-in’ signaling in human T cells, migrating in response to chemokines, that mediates integrin recruitment to the leading edge.

LFA-1 nanoclusters integrate TCR stimulation strength to tune T-cell cytotoxic activity

T-cell cytotoxic function relies on the cooperation between the highly specific but poorly adhesive T-cell receptor (TCR) and the integrin LFA-1. How LFA-1-mediated adhesion may scale with TCR stimulation strength is ill-defined. Here, we show that LFA-1 conformation activation scales with TCR stimulation to calibrate human T-cell cytotoxicity. Super-resolution microscopy analysis reveals that >1000 LFA-1 nanoclusters provide a discretized platform at the immunological synapse to translate TCR engagement and density of the LFA-1 ligand ICAM-1 into graded adhesion. Indeed, the number of high-affinity conformation LFA-1 nanoclusters increases as a function of TCR triggering strength. Blockade of LFA-1 conformational activation impairs adhesion to target cells and killing. However, it occurs at a lower TCR stimulation threshold than lytic granule exocytosis implying that it licenses, rather than directly controls, the killing decision. We conclude that the organization of LFA-1 into nanoclusters provides a calibrated system to adjust T-cell killing to the antigen stimulation strength.

Probing mechanical interaction of immune receptors and cytoskeleton by membrane nanotube extraction

The role of force application in immune cell recognition is now well established, the force being transmitted between the actin cytoskeleton to the anchoring ligands through receptors such as integrins. In this chain, the mechanics of the cytoskeleton to receptor link, though clearly crucial, remains poorly understood. To probe this link, we combine mechanical extraction of membrane tubes from T cells using optical tweezers, and fitting of the resulting force curves with a viscoelastic model taking into account the cell and relevant molecules. We solicit this link using four different antibodies against various membrane bound receptors: antiCD3 to target the T Cell Receptor (TCR) complex, antiCD45 for the long sugar CD45, and two clones of antiCD11 targeting open or closed conformation of LFA1 integrins. Upon disruption of the cytoskeleton, the stiffness of the link changes for two of the receptors, exposing the existence of a receptor to cytoskeleton link—namely TCR-complex and open LFA1, and does not change for the other two where a weaker link was expected. Our integrated approach allows us to probe, for the first time, the mechanics of the intracellular receptor–cytoskeleton link in immune cells.

45 Behavior and Effect of Nanoparticles on Neutrophil Recruitment in the Pulmonary Microcirculation

Abstract NP exposure is frequently associated with adverse cardiovascular effects. A small fraction of NP deposited in lung has been shown to penetrate into the blood circulation. However, the interactions and effects of NP in the pulmonary microcirculation under healthy and pathophysiologic conditions such as LPS-induced acute lung injury are largely unknown. To visualize and quantify NP dynamics and pulmonary vascular innate immune responses elicited by different surface-modified NPs in real time, we applied state-of-the-art intra-vital microscopy in the alveolar region of murine lungs. I.v. injected polyethylene-glycol-amine (aPEG)-QDs and carboxyl-QDs exhibited a half-life time of 30 and 6 mins in the microcirculation and did not permanently interact with vessel wall. Blood flow velocity was significantly decreased after aPEG-QDs application in healthy mice, but did not further decrease the reduced microcirculatory perfusion after LPS treatment. In healthy mice, aPEG-QDs elicited a significant increase in neutrophil number in alveolar micro-vessels from 30 min upon application compared to controls, whereas cQDs induced only a slight neutrophil increment. Accordingly, the crawling velocity of neutrophils in pulmonary micro-vessels was significantly reduced after aPEG-QDs application. No effect of QDs on neutrophil number and crawling was detected in the LPS group. Importantly, neutrophil recruitment by aPEG-QDs was diminished by prior i.v. application of anti-TNFa, anti-E-selectin and anti-LFA-1 blocking antibodies. Taken together our data suggest that aPEG-QDs induced microvascular inflammation involving TNFa secretion, expression of the vascular cell adhesion molecule E-selectin and neutrophil integrin LFA-1, whereas QDs application did not alter LPS-dependent microvascular inflammation.

Decreased memory persistence in Piezo1 deficient T cells ameliorates disease progression in autoimmune mouse models

Abstract To mount a successful immune response, T cells must successfully (1) migrate from the bloodstream into secondary lymphoid organs (naïve) or inflamed tissue (effector), and (2) form an effective immunological synapse for activation. Although the molecular interactions of these processes have been well described, the emergence of novel biophysical approaches has revealed that both critical processes require mechanosensing. Previously we have demonstrated that the mechanosensitive cation channel, Piezo1, forms a complex with activated integrin LFA-1, an important regulator of T cell migration and T cell receptor-triggered T cell activation. Therefore, we hypothesized that Piezo1 deficiency in T cells would diminish T cell activation and homing.To investigate Piezo1’s role on T cell function, we have generated T cell-specific Piezo1 knockout mice (P1cKO) by crossing Piezo1-floxed mice to CD4-Cre mice. Initial studies in vitro showed that under polarizing conditions P1cKO T cells produce more Th1 and Th17 inflammatory cytokines. However, when challenged with experimental autoimmune encephalomyelitis (EAE) and Graft-vs-Host Disease (GVHD), P1cKO mice showed a significant decrease in disease phenotype. Moreover, adoptive transfer mouse models of EAE show that activated P1cKO T cell transfer fails to establish disease phenotype. Upon further investigation, we found similar numbers of P1cKO T cells at sites of inflammation early in disease, but there was a decreased persistence of effector and central memory P1cKO T cells. Taken together, our data suggests that Piezo1 plays an important in role in the development and maintenance of T cell memory pools, while potentially contributing to T cell activation and migration. This project was supported by grants from the NIH (TL1 TR002549, T32 GM007250, T32 AI089474), the St. Baldrick's Foundation Innovation Fund, the Theresia G. & Stuart F. Kline Family Foundation, and the Karen & Alan Krause Pediatric Immunotherapy Innovation and Education Fund.

CD9 identifies and regulates a highly functional and unique subset of T follicular helper (Tfh) cells necessary for the promotion of antibodies during infection

Abstract T follicular helper (Tfh) cells comprise a subset of CD4 +T helper (Th) cells phenotypically and functionally distinct from Th1 and Th2 cell subsets. Tfh cells are located within B cell follicles and germinal centers (GC), where they secrete the cytokines IL-21 and interferon-γ (IFN-γ) which aid in B cell proliferation and differentiation. CD9, a tetraspanin, has been shown to accumulate on CD4 T cells at the immunological synapse, playing a role in co-stimulation and stabilization of the synapse via regulation of the integrins LFA-1 and VLA-4. CD9 has been shown to be expressed on activated CD4 T cells, but whether it remains upregulated specifically on Tfh cells is unknown. We identified a distinct population of CD9-expressing Tfh cells (CD9 hi) following acute viral infections and examined their role in promoting GC responses. Following acute LCMV infection, CD9 hiTfh cells are found in the follicles and GCs, yet exhibited enhanced proliferation and migratory capacity to the chemokines CXCL12 and CXCL13. Epigenetically, CD9 hiTfh cells demonstrated a distinct transcriptional profile and chromatin architecture from their CD9 locounterpart, with an upregulation of cell cycling, PI3K, and integrin-regulated genes. Functionally, CD9 hiTfh cells had elevated VLA-4 expression and were the predominant producers of IL-21 and IFN-γ, indicating a specific role in B cell maturation and differentiation. Furthermore, deletion of CD9 did not alter Tfh cell development, but lead to their reduction of IL-21 and IFN-γ production and a decrease in overall antibody responses. Therefore, we identified that CD9 hiTfh cells are a highly functional and unique subset necessary for the promotion of antibodies during infection. R01 AR073912

LFA-1 Activation in T-Cell Migration and Immunological Synapse Formation.

Integrin LFA-1 plays a critical role in T-cell migration and in the formation of immunological synapses. LFA-1 functions through interacting with its ligands with differing affinities: low, intermediate, and high. Most prior research has studied how LFA-1 in the high-affinity state regulates the trafficking and functions of T cells. LFA-1 is also presented in the intermediate-affinity state on T cells, however, the signaling to activate LFA-1 to the intermediate-affinity state and the role of LFA-1 in this affinity state both remain largely elusive. This review briefly summarizes the activation and roles of LFA-1 with varied ligand-binding affinities in the regulation of T-cell migration and immunological synapse formation.

Allosteric targeting resolves limitations of earlier LFA-1 directed modalities

Integrins are a family of cell surface receptors well-recognized for their therapeutic potential in a wide range of diseases. However, the development of integrin targeting medications has been impacted by unexpected downstream effects, reflecting originally unforeseen interference with the bidirectional signalling and cross-communication of integrins. We here selected one of the most severely affected target integrins, the integrin lymphocyte function-associated antigen-1 (LFA-1, αLβ2, CD11a/CD18), as a prototypic integrin to systematically assess and overcome these known shortcomings. We employed a two-tiered ligand-based virtual screening approach to identify a novel class of allosteric small molecule inhibitors targeting this integrin’s αI domain. The newly discovered chemical scaffold was derivatized, yielding potent bis-and tris-aryl-bicyclic-succinimides which inhibit LFA-1 in vitro at low nanomolar concentrations. The characterisation of these compounds in comparison to earlier LFA-1 targeting modalities established that the allosteric LFA-1 inhibitors (i) are devoid of partial agonism, (ii) selectively bind LFA-1 versus other integrins, (iii) do not trigger internalization of LFA-1 itself or other integrins and (iv) display oral availability. This profile differentiates the new generation of allosteric LFA-1 inhibitors from previous ligand mimetic-based LFA-1 inhibitors and anti-LFA-1 antibodies, and is projected to support novel immune regulatory regimens selectively targeting the integrin LFA-1. The rigorous computational and experimental assessment schedule described here is designed to be adaptable to the preclinical discovery and development of novel allosterically acting compounds targeting integrins other than LFA-1, providing an exemplary approach for the early characterisation of next generation integrin inhibitors.

Exploration of immunosuppressive features of the tumor microenvironment within hepatic and non-hepatic tumors of urothelial origin.

562 Background: Recent data suggest that patients with liver metastases (mets) are resistant to immune checkpoint inhibition (CPI) independent of historical biomarkers of CPI efficacy, raising the question of whether liver mets may be associated with an immunosuppressive tumor microenvironment (TME). We investigated the immune TME of hepatic and non-hepatic mets compared to primary tumors in advanced urothelial carcinoma (UC) tissue samples. Methods: NextGen sequencing (NGS) of DNA (592-gene/whole exome) and RNA (whole transcriptome) from UC tissue samples (N=4746) was performed at Caris Life Sciences (Phoenix, AZ). Immune cell infiltration was estimated by RNA expression deconvolution (MCP-counter). PD-L1 expression (SP142: immune cell stain ≥ 5%; 22c3: CPS ≥ 10) was assessed by immunohistochemistry (IHC). Deficient mismatch repair/high microsatellite instability (dMMR/MSI-H) was tested by IHC/NGS. Real-world overall survival (OS) information was obtained from insurance claims data and Kaplan-Meier estimates were calculated. Mann–Whitney U and X2/Fischer-Exact tests were applied where appropriate, with p-values adjusted for multiple comparisons (Benjamini-Hochberg). *P<0.05. Results: UC samples included 3158 (66.5%) from primary site, 1344 (28.3%) from non-hepatic mets, and 244 (5.1%) from hepatic mets. Compared to primary tumors, hepatic mets had decreased CD8+ T and B cells (0.55* and 0.29-fold*) but increased monocytic lineage cells (1.23-fold*), while non-hepatic mets had increased CD8+ T, NK, and monocytic lineage cells (1.28*, 1.27*, 1.31-fold*) with no difference in B cells (1.05-fold). Hepatic mets had decreased expression of integrin LFA-1/ ITGAL (0.77-fold*), as well as hyaluronic acid (HA) receptor CD44 and synthase HAS2 (0.61 and 0.61-fold*), compared to primary tumors, whereas expression of these genes and LFA-1 ligand ICAM1 was increased in non-hepatic mets (1.08 to 1.30-fold*). Hepatic mets had increased expression of immunosuppressive cytokines CCL2 and CXCL2 (1.72* and 2.32-fold*) and decreased expression of pro-inflammatory cytokines CCL5 and CXCL10 (0.63* and 0.79-fold*) compared to primary tumors. PD-L1+ IHC was less frequent in hepatic mets compared to primary tumors and non-hepatic mets. TMB-High (≥10 mut/MB) and dMMR/MSI-H rates were similar across tumor sites. Hepatic mets (N=40) were associated with worse OS from the start of pembrolizumab compared to non-hepatic mets (N=177) (19.6 vs 4.4 months, HR 3.01, 95% CI 1.91-4.75, p<0.0001). Conclusions: This is the largest analysis of hepatic and non-hepatic met TMEs compared to primary tumor in advanced UC. Lower PD-L1 expression and differences in immune TME composition in liver mets may contribute to CPI resistance. Further analysis is warranted to determine underlying molecular mechanisms resulting in a TME that reduces response to CPI for patients with UC and liver mets.

Understanding how antigen mobility and adhesion molecules influence B cell activation.

B cells are activated by specific binding events between antigen and the B cell receptor (BCR). B cells sense physical properties of the antigen-presenting cell, such as antigen mobility, through forces loaded onto BCR-antigen bonds. The LFA-1-ICAM-1 interaction also promotes traction forces at the B cell immune synapse and has been shown to promote B cell activation. In contrast to the biochemical mechanisms governing B cell activation, the role of physical factors remains not fully explored. Here, we systematically explore the role of antigen mobility on B cell activation, investigating a role for both the BCR and LFA-1 integrin. We control forces loaded onto BCR-antigen bonds by manipulating substrate viscosity and controlling antigen density. Understanding how forces on BCR-antigen bonds influence B cell behaviour can help us develop better predictive models of B cell activation and routes to control it.

Ocrelizumab Impairs the Phenotype and Function of Memory CD8+ T Cells: A 1-Year Longitudinal Study in Patients With Multiple Sclerosis.

Depleting CD20+ B cells is the primary mechanism by which ocrelizumab (OCRE) is efficient in persons with multiple sclerosis (pwMS). However, the exact role of OCRE on other immune cell subsets directly or indirectly remains elusive. The purpose of this study is to characterize the dynamics of peripheral immune cells of pwMS on OCRE. We collected blood samples from 38 pwMS before OCRE onset (T0) and at 6 and 12 months (T6, T12) after initiation. To cover the immune cell diversity, using mass cytometry time of flight, we designed a 38-parameter panel to analyze B, T, and innate immune cell markers and CNS migratory markers. In parallel, viral-specific CD8+ T-cell responses were assessed by the quantification of interferon-γ secretion using the enzyme-linked immunospot assay on cytomegalovirus, Epstein-Barr virus, and influenza stimulations. Beside B-cell depletion, we observed a loss in memory CD8+CD20+ and central memory CD8+ T cells but not in CD4+CD20+ T cells already at T6 and T12 (p < 0.001). The loss of memory CD8+ T cells correlated with a lower CXCR3 expression (p < 0.001) and CNS-related LFA-1 integrin expression (p < 0.001) as well as a reduced antiviral cellular immune response observed at both time points (p < 0.001). Of note, we did not observe major changes in the phenotype of the other cell types studied. Seven of 38 (18.4%) patients in our cohort presented with infections while on OCRE; 4 of which were switched from dimethyl fumarate. Finally, using a mixed linear model on mass cytometry data, we demonstrated that the immunomodulation induced by previous disease-modifying therapies (DMTs) was prolonged over the period of the study. In addition to its well-known role on B cells, our data suggest that OCRE also acts on CD8+ T cells by depleting the memory compartment. These changes in CD8+ T cells may be an asset in the action of OCRE on MS course but might also contribute to explain the increased occurrence of infections in these patients. Finally, although more data are needed to confirm this observation, it suggests that clinicians should pay a special attention to an increased infection risk in pwMS switched from other DMTs to OCRE.

Effector Memory-Expressing CD45RA (TEMRA) CD8+ T Cells from Kidney Transplant Recipients Exhibit Enhanced Purinergic P2X4 Receptor-Dependent Proinflammatory and Migratory Responses.

The mechanisms regulating CD8+ T cell migration to nonlymphoid tissue during inflammation have not been fully elucidated, and the migratory properties of effector memory CD8+ T cells that re-express CD45RA (TEMRA CD8+ T cells) remain unclear, despite their roles in autoimmune diseases and allotransplant rejection. We used single-cell proteomic profiling and functional testing of CD8+ T cell subsets to characterize their effector functions and migratory properties in healthy volunteers and kidney transplant recipients with stable or humoral rejection. We showed that humoral rejection of a kidney allograft is associated with an accumulation of cytolytic TEMRA CD8+ T cells in blood and kidney graft biopsies. TEMRA CD8+ T cells from kidney transplant recipients exhibited enhanced migratory properties compared with effector memory (EM) CD8+ T cells, with enhanced adhesion to activated endothelium and transmigration in response to the chemokine CXCL12. CXCL12 directly triggers a purinergic P2×4 receptor-dependent proinflammatory response of TEMRA CD8+ T cells from transplant recipients. The stimulation with IL-15 promotes the CXCL12-induced migration of TEMRA and EM CD8+ T cells and promotes the generation of functional PSGL1, which interacts with the cell adhesion molecule P-selectin and adhesion of these cells to activated endothelium. Although disruption of the interaction between functional PSGL1 and P-selectin prevents the adhesion and transmigration of both TEMRA and EM CD8+ T cells, targeting VLA-4 or LFA-1 (integrins involved in T cell migration) specifically inhibited the migration of TEMRA CD8+ T cells from kidney transplant recipients. Our findings highlight the active role of TEMRA CD8+ T cells in humoral transplant rejection and suggest that kidney transplant recipients may benefit from therapeutics targeting these cells.

CBA strain mice as a model of spontaneous carcinogenesis

The review analyzes some parameters of CBA mice-males as model of spontaneous carcinogenesis characterizing adhesive and adaptive disorders. A weakening of the hepatocytes mutual adhesiveness force was noted already in early ontogenesis (5–10 days of postnatal development). This violation persisted and enhanced during hepatocarcinogenesis. A decrease of the β2 leukocyte integrins LFA-1 and Mac-1 expression on peripheral blood cells as well as an increase of the interleukins 6 and 10 in blood serum were determined during ontogenesis. It is significant for weakening the liver cells contact interactions (mutual adhesiveness) as well as immunity effectors and tumor cells interactions. A disbalance of the adaptive reactions and life quality important components was revealed in the CBA mice-males ontogenesis. Number of dopaminergic neurons and the neurogenesislevel in CBA micemales were decreasing. This does not contradict the dynamics of chronic stress and the aging process: an increase in the catabolic stress hormone corticosterone, a decrease in the anabolic hormone testosterone in the blood serum, a decrease in motor activity, signs of cachexia and alopecia, as well as a violation of immunological parameters.CBA mice-males with an assessment of parameters characterizing adhesive and adaptive disorders during spontaneous carcinogenesis (the hepatocytes mutual adhesiveness forсe, the expression of β2 leukocyte integrins LFA-1 and Mac-1 on peripheral blood cells, the content of interleukins 6, 10, corticosterone and testosterone in blood serum, the number of dopaminergic neurons in the midbrain during ontogenesis) as well as the frequency and size of tumours, lifespan and somatic status of animals can be used as a scientifically- and evidence-based test system to study cytostatic drugs as well as non-toxic geroprotective medications for prevention and treatment of cancer in individuals with an increased risk of malignant neoplasms developing especially hepatocellular carcinoma.