Homing Receptor Research Articles

Natural killer cell biology and therapy in multiple myeloma: challenges and opportunities.

Despite therapeutic advancements, multiple myeloma (MM) remains incurable. NK cells have emerged as a promising option for the treatment of MM. NK cells are heterogenous and typically classified based on the relative expression of their surface markers (e.g., CD56 and CD16a). These cells elicit an antitumor response in the presence of low mutational burden and without neoantigen presentation via germline-encoded activating and inhibitory receptors that identify the markers of transformation present on the MM cells. Higher NK cell activity is associated with improved survival and prognosis, whereas lower activity is associated with advanced clinical stage and disease progression in MM. Moreover, not all NK cell phenotypes contribute equally toward the anti-MM effect; higher proportions of certain NK cell phenotypes result in better outcomes. In MM, the proportion, phenotype, and function of NK cells are drastically varied between different disease stages; this is further influenced by the bone marrow microenvironment, proportion of activating and inhibitory receptors on NK cells, expression of homing receptors, and bone marrow hypoxia. Antimyeloma therapies, such as autologous stem cell transplant, immunomodulation, proteasome inhibition, and checkpoint inhibition, further modulate the NK cell landscape in the patients. Thus, NK cells can naturally work in tandem with anti-MM therapies and be strategically modulated for improved anti-MM effect. This review article describes immunotypic and phenotypic differences in NK cells along with the functional changes in homeostatic and malignant states and provides expert insights on strategies to harness the potential of NK cells for improving outcomes in MM.

Fusobacterium nucleatum to promote esophageal squamous cell carcinoma progression via CCL20/CCR6-mediated migration of macrophages to the tumour micro environment.

e14668 Background: Esophageal squamous cell carcinoma (ESCC) is one of the most common digestive malignant tumor in China. Recent studies have shown that Fusobacterium nucleatum ( F. nucleatum) promotes ESCC progression through various mechanisms. One of them is about changing the tumor micro- environment through cytokine–cytokine receptor interaction. Methods: From January 2022 to June 2023, a total of 34 patients with ESCC from 4th Hospital of Hebei Medical University thoracic surgery were enrolled. All of the patients did not apply any neoadjuvant therapy before and received radical resection. Real-time reverse transcriptase - PCR (RT-PCR) were performed to examine the expressions of F. nucleatum in tumor tissues and para-tumor tissue. According to the CT values of the RT-PCR results, the level of the F. nucleatum infection could be separated in two groups - positive group and negative group. Immunohistochemistry (IHC) staining were used to examine the expressions of chemokine CCL20 in both groups. Immunofluorescence (IF) was characterised homing receptors CCR6 on CD206+ macrophages. In addition, transwell assay was carried on to quantify macrophages migration ability towards chemokines CCL20 in vitro. Results: F. nucleatum DNA positivity was significantly associated with higher expression of chemokine CCL20 and accumulation of CD68+CD206+ macrophages. F. nucleatum DNA positivity was also significantly correlated with worse histopathological grading. Otherwise, there were no significant correlation between F. nucleatum infection and gender, age, tobacco or alcohol use, T or N grade, TNM stage, tumor locations, blood vessel or nerve invasion and tumor size. IHC showed that the expression of CCL20 were higher in F. nucleatum DNA positive tumor tissue. After coculture with F. nucleatum and KYSE30 cell lines in vitro, the CCL20 production by KYSE30 cells were accelerated. In addition, immunofluorescence showed that CCL20 could recruit M2-like macrophages into the tumor environment by bonding CCR6 existed on the cell surface. Furthermore, the migration ability of macrophages was distinctly elevated by CCL20 result from F. nucleatum infection. Conclusions: F. nucleatum promotes esophageal squamous cell carcinoma progression via CCL20/CCR6-mediated migration of M2-like macrophages to the tumor micro- environment and deteriorates the suppression of the local immune micro- environment within the tumor. Such bacteria may be a biomarker to predict the efficacy of immunotherapy in ESCC. [Table: see text]

GPR15-dependent T cell recruitment in the acute phase of viral myocarditis is associated with improved virus elimination and outcome

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): DZHK (German Centre for Cardiovascular Research) Background Myocarditis is an inflammatory heart disease that is primarily caused by viral pathogens such as Coxsackievirus B3 (CVB3). The clinical course of myocarditis has a wide spectrum of outcomes, ranging from complete recovery to cardiac dysfunction and dilated cardiomyopathy. The G protein-coupled receptor 15 (GPR15) has been identified as a T cell homing receptor associated with inflammatory diseases. Purpose The aim of this study was to address the following questions: Does GPR15 deficiency (i) lead to differences in immune cell infiltration or inflammation in the acute phase of myocarditis; (ii) does it affect elimination of CVB3 and thus outcome; (iii) does it affect immune cell chemotaxis or functionality? Therefore, GPR15-deficient (Gpr15gfp/gfp) and WT mice were infected with CVB3 to study the acute and subacute phase of myocarditis. Results In the subacute phase of myocarditis 16 days p.i., virus persistence was observed in more than 85% of Gpr15gfp/gfp mice, while more than 70% of WT mice successfully cleared the virus. In addition, Gpr15gfp/gfp mice showed reduced cardiac function accompanied by increased fibrosis compared to WT mice. Based on these findings, we analysed the acute phase of myocarditis in more detail. Comparing the infected genotypes, no significant differences were found at 6 days p.i. in contrast to 5 and 7 days p.i.. After 5 days p.i., Gpr15gfp/gfp mice showed significantly lower gene expression of inflammatory cytokines and immune cell markers, especially regulatory T cells. In contrast, after 7 days p.i., inflammatory cytokines and markers for regulatory and cytotoxic T cells were significantly increased in infected Gpr15gfp/gfp mice compared to infected WT mice. RNASeq confirmed that the response to the virus did not decrease from day 6 to 7 in infected Gpr15gfp/gfp mice, as observed in infected WT mice. Furthermore, gene ontology (GO) analyses revealed altered chemotaxis and increased cytotoxic T cell-related GO terms in Gpr15gfp/gfp mice 7 days p.i.. In addition, we demonstrated in vitro that chemotaxis of both regulatory and cytotoxic T cells depends on the interaction between GPR15 and its ligand GPR15L and that loss of GPR15 abrogates chemotaxis of T cells towards GPR15L. Conclusion Here we show that GPR15 deficiency leads to reduced virus elimination in the heart and thus to adverse remodelling and impaired cardiac function. Delayed recruitment of regulatory T cells was associated with prolonged persistence of cytotoxic and regulatory T cells in Gpr15gfp/gfp mice. In addition, RNASeq revealed a prolonged inflammatory response and altered chemotaxis in Gpr15gfp/gfp mice. Through in vitro studies, we identified GPR15L as an important chemokine for the recruitment of regulatory and cytotoxic T cells. In conclusion, insufficient virus elimination could be caused by delayed recruitment of T cells, leading to a prolonged inflammatory response and an adverse outcome in GPR15-deficient mice.

#610 Alterations in frequency and function exhausted memory B cells in lupus nephritis and systemic lupus erythematosus

Abstract Background and Aims Various B cell abnormalities have been implicated in the pathogenesis of LN, and our previous studies have demonstrated that memory B cells assume pathogenic relevance in disease relapse. Memory B cell exhaustion is a B lymphocyte aberration initially reported in chronic human immunodeficiency virus (HIV) infection, and was later also observed in chronic graft versus host disease (cGVHD) and autoimmune disorders. The pathogenic roles of exhausted memory B cells in LN and disease relapse remains unclear. We will validate the significance role of exhausted B cell in the pathogenesis of LN. Method Classical memory (CD19 + CD21 + CD27+) and exhausted B cells (CD19 + CD21 – CD27–) were measured in LN patients with multiple relapses (MR) (n=15) or no relapse (NR) (n=15) during disease remission. B cell-related cytokines, homing and inhibitory receptors, proliferation and calcium mobilization in classical and exhausted memory B cells were also assessed. Using single-cell RNA sequencing data from NIH and GEO, we also performed bioinformatics analysis to identify genes and pathways relevant to memory and exhausted B cells in SLE, LN and healthy controls. Results The MR group exhibited higher proportion of circulating exhausted memory B cells compared to NR. Blood levels of IL-6, BAFF and IL-21 in MR patients were higher than the NR group. The MR had higher blood levels of Siglec-6, CXCR3 and CD62L than the NR group. Expression of inhibitory receptors CD22, CD85j, CD183 and FCRL4 in exhausted B cells were increased in the MR group compared to the NR group. Exhausted B cells from MR patients also showed decreased proliferation compared to NR patients and impaired calcium mobilization in response to B-cell receptor triggering. STAT1, XAF1, MX1, IFI44L, EPSTI1, LCP1, OAS1, NEAT1, IFI16, IFI44 in exhausted B cells and XAF1, MX1, IFI44L in memory B cells play a pathogenic role in LN patients (Figs. 1 and 2). SLE patients also show increased proportion of exhausted B cells compared to healthy control and the expression of STAT1, XAF1, MX1, IFI44L correlate positively with the proportion of exhausted B cells. Conclusion Our results suggested that altered numbers and function of exhausted B cells may have pathogenic significance in SLE and LN.

MAdCAM-1 co-stimulation combined with retinoic acid and TGF-β induces blood CD8+ T cells to adopt a gut CD101+ TRM phenotype

Resident memory T cells (TRMs) help control local immune homeostasis and contribute to tissue protective immune responses. The local cues that guide their differentiation and localization are poorly defined. We demonstrate that MAdCAM-1, a ligand for the gut homing receptor α4β7 integrin, in the presence of retinoic acid and TGF-β provide a costimulatory signal that induces blood CD8+ T cells to adopt a TRM -like phenotype. These cells express CD103 (integrin αE) and CD69, the two major TRM cell surface markers, along with CD101. They also express CCR5, CCR9 and α4β7, three receptors associated with gut homing. A subset also express E-cadherin, a ligand for αEβ7. Fluorescent lifetime imaging indicated an αEβ7 and E-cadherin cis interaction on the plasma membrane. This report advances our understanding of the signals that drive the differentiation of CD8+ T cells into TRMs and provides a means to expand these cells in vitro, thereby affording an avenue to generate more effective tissue specific immunotherapies.

Chemokines and lymphocyte homing in Sjögren's syndrome.

Sjögren's syndrome (SS) is a chronic systemic autoimmune disease that typically presents with lymphocyte, dendritic cell, and macrophage infiltration of exocrine gland ducts and the formation of ectopic germinal centers. The interactions of lymphocyte homing receptors and addressins and chemokines and their receptors, such as α4β7/MAdCAM-1, LFA-1/ICAM-1, CXCL13/CXCR5, CCL25/CCR9, CX3CL1/CX3CR1, play important roles in the migration of inflammatory cells to the focal glands and the promotion of ectopic germinal center formation in SS. A variety of molecules have been shown to be involved in lymphocyte homing, including tumor necrosis factor-α, interferon (IFN)-α, IFN-β, and B cell activating factor. This process mainly involves the Janus kinase-signal transducer and activator of transcription signaling pathway, lymphotoxin-β receptor pathway, and nuclear factor-κB signaling pathway. These findings have led to the development of antibodies to cell adhesion molecules, antagonists of chemokines and their receptors, compounds interfering with chemokine receptor signaling, and gene therapies targeting chemokines and their receptors, providing new targets for the treatment of SS in humans. The aim of this study was to explore the relationship between lymphocyte homing and the pathogenesis of SS, and to provide a review of recent studies addressing lymphocyte homing in targeted therapy for SS.

Local Allergic Rhinitis

Local allergic rhinitis (LAR) is defined by a clinical history suggestive of allergic rhinitis (AR), negativity of systemic IgE measurement and positive response to nasal allergen challenge (NAC). The term local respiratory allergy includes LAR, local allergic asthma (positive response in bronchial allergen challenge) and dual allergic rhinitis defined by the coexistence of AR and LAR. LAR worsens in severity and presence of comorbidities over time, and it is an independent entity from AR. Prevalence is higher in Mediterranean countries. LAR onset occurs during childhood in 36% of cases. Physiopathological features of LAR are: increased nasal eosinophilic inflammation, tryptase and eosinophil cationic protein, and presence of nasal specific IgE in secretions of 20-40% of subjects. A recent study demonstrated increase in sequential class switch recombination to IgE markers in mucosa of LAR with accumulation of IgE+ CD38+ plasmablasts. Moreover, there is increased expression in B cells of mucosal homing receptors CXCR3+ and CXCR4 in peripheral blood, with accumulation of Th9 and Th2 cells. NAC is the gold standard in the diagnosis of LAR. The measurement of specific IgE in nasal secretions basophil activation test or are still not suitable for diagnosis. There is ample evidence of the usefulness of allergen immunotherapy in the treatment in LAR after 4 DBPCRT in 152 patients. In conclusion, knowledge about LAR is continuously increasing, with detailed definition of physiopathological mechanisms and new phenotypes. More awareness of the disease should be promoted among different specialists, and NAC must be considered an essential diagnostic tool in any age group, including children.

Abstract 5251: RNA primed SMAR-T cells against multiple driver mutations, all HLA's designed for first line therapy

Abstract Success of immune checkpoint inhibitors (e.g., anti-PD1 antibodies) have revolutionized cancer immunotherapy by demonstrating that a patient’s own T-cells recognize and treat cancer. The efficacy of PD-1 blockade is driven by recruitment of new T-cells from blood rather than via activation of pre-existing tumor infiltrating lymphocytes (Yost K.E., et al. Nat. Med. 2019). However, anti-PD1 therapy is most effective in ~5% of malignancies i.e., cancers with high mutational burden. Hence, the challenge of addressing most lower mutational burden cancers (the ~95%) needs an alternate treatment strategy. We address this challenge by using RNA to prime and expand peripheral T-cells to cancer-specific mutations ex-vivo. Using our proprietary, patented, and robust manufacturing method, we can generate T-cell populations reactive to as low as 8 and as high as 40 cancer-specific mutant proteins. In-vitro, these T-cells have cancer mutation-specific cytotoxicity and do not kill the normal cells. Further, the T-cells express homing receptors enabling them to infiltrate tumors and express high levels of TNFα and IFNγ, which are associated with effective tumor cytotoxicity and pro-inflammatory modification of tumor microenvironment (TME). Additional characterization shows these cells to be predominantly CD4+ and CD8+ T-cells bearing central and effector memory phenotypic with negligible regulatory or exhausted T-cells. We believe our T-cells can be used for cellular therapy in conjunction with, or as an alternative to, immune checkpoint inhibitors to treat lower mutational burden cancers present in most patients. Citation Format: Alfred E. Slanetz, Sriram Srivatsa, Farzona Muzaffar, Walter Barry, David Ryan, Salim Metri, Michael Slanetz. RNA primed SMAR-T cells against multiple driver mutations, all HLA's designed for first line therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5251.

Immune mapping of human tuberculosis and sarcoidosis lung granulomas.

Tuberculosis (TB) and sarcoidosis are both granulomatous diseases. Here, we compared the immunological microenvironments of granulomas from TB and sarcoidosis patients using in situ sequencing (ISS) transcriptomic analysis and multiplexed immunolabeling of tissue sections. TB lesions consisted of large necrotic and cellular granulomas, whereas "multifocal" granulomas with macrophages or epitheloid cell core and a T-cell rim were observed in sarcoidosis samples. The necrotic core in TB lesions was surrounded by macrophages and encircled by a dense T-cell layer. Within the T-cell layer, compact B-cell aggregates were observed in most TB samples. These B-cell clusters were vascularized and could contain defined B-/T-cell and macrophage-rich areas. The ISS of 40-60 immune transcripts revealed the enriched expression of transcripts involved in homing or migration to lymph nodes, which formed networks at single-cell distances in lymphoid areas of the TB lesions. Instead, myeloid-annotated regions were enriched in CD68, CD14, ITGAM, ITGAX, and CD4 mRNA. CXCL8 and IL1B mRNA were observed in granulocytic areas in which M. tuberculosis was also detected. In line with ISS data indicating tertiary lymphoid structures, immune labeling of TB sections expressed markers of high endothelial venules, follicular dendritic cells, follicular helper T cells, and lymph-node homing receptors on T cells. Neither ISS nor immunolabeling showed evidence of tertiary lymphoid aggregates in sarcoidosis samples. Together, our finding suggests that despite their heterogeneity, the formation of tertiary immune structures is a common feature in granulomas from TB patients.

GPR15-mediated T cell recruitment during acute viral myocarditis facilitated virus elimination and improved outcome

Viral myocarditis is characterized by infiltration of mononuclear cells essential for virus elimination. GPR15 has been identified as a homing receptor for regulatory T cells in inflammatory intestine diseases, but its role in inflammatory heart diseases is still elusive. Here we show that GPR15 deficiency impairs coxsackievirus B3 elimination, leading to adverse cardiac remodeling and dysfunction. Delayed recruitment of regulatory T cells in GPR15-deficient mice was accompanied by prolonged persistence of cytotoxic and regulatory T cells. In addition, RNA sequencing revealed prolonged inflammatory response and altered chemotaxis in knockout mice. In line, we identified GPR15 and its ligand GPR15L as an important chemokine receptor–ligand pair for the recruitment of regulatory and cytotoxic T cells. In summary, the insufficient virus elimination might be caused by a delayed recruitment of T cells as well as delayed interferon-γ expression, resulting in a prolonged inflammatory response and an adverse outcome in GPR15-deficient mice.

CD8+ T cells in fetal membranes display a unique phenotype, and their activation is involved in the pathophysiology of spontaneous preterm birth.

Preterm labor/birth is the leading cause of perinatal mortality and morbidity worldwide. Previous studies demonstrated that T cells were crucial for maintaining maternal-fetal immune tolerance during the first trimester of pregnancy; however, their phenotypes and functions in labor and delivery remain largely unknown. We recruited three cohorts of women at delivery for T-cell immunophenotyping in the placentas, fetal membranes, umbilical cord blood, and maternal peripheral blood. Our data showed a differential enrichment of T cells during the third trimester of human pregnancy, with CD4+ T cells being more observable within the umbilical cord blood, whereas CD8+ T cells became relatively more abundant in fetal membranes. CD4+ and CD8+ T cells derived from fetal membranes were dominated by effector memory T cells and exhibited extensive expression of activation markers but decreased expression of homing receptor. In comparison with term births, fetal membrane CD8+ T cells, especially the central memory subset, were significantly increased in frequency and showed more profound activation in spontaneous preterm birth patients. Finally, using an allogeneic mouse model, we found that T-cell-activation-induced preterm birth could be alleviated by the depletion of CD8+ T but not CD4+ T cells in vivo. Collectively, we showed that CD8+ T cells in fetal membranes displayed a unique phenotype, and their activation was involved in the pathophysiology of spontaneous preterm birth, which provides novel insights into the immune mechanisms of preterm birth and potential targets for the prevention of this syndrome. © 2023 The Pathological Society of Great Britain and Ireland.

North American Adult T-Cell Leukemia/Lymphoma Has Frequent Mutations in CCR4 and Responds in Vitro to a Small Molecule CCR4 Antagonist, CCR4-351

Adult T-cell leukemia/lymphoma (ATLL) is a rare and aggressive disease of malignant CD4+ T cells that develops in human T-lymphotropic virus-1 (HTLV-1) carriers. Patients diagnosed with ATLL have the worst survival among all peripheral T-cell lymphomas. There is an urgent need for in-depth understanding of its pathogenesis and development of new treatment strategies. We and others have shown that ATLLs diagnosed in the Japanese (J-ATLL) and North American (NA-ATLL) patients have differences in clinical characteristics and immune-genetic landscape. Among the most frequently mutated genes in J-ATLL cohorts is CCR4, a chemokine receptor that is targeted by C-terminal truncation mutations in one third of the cases. These mutations result in a more stabilized surface CCR4 and have been reported to cause elevated Akt activation following chemokine stimulation. Since our previous targeted exon sequencing study did not include CCR4, this work was initiated to assess CCR4 mutation frequency in NA-ATLL cases and to evaluate the preclinical activity of a small molecule CCR4 antagonist. This is because, although an anti-CCR4 mAb, mogamulizumab, has been approved in Japan to treat ATLL, this therapy failed in a Phase 2 trial among patients outside of Japan. Thus, mogamulizumab is not available as a routine treatment for NA-ATLL patients. We compiled CCR4 gene status data from bulk RNA-seq (n=10) and whole genome sequencing (WGS) analysis (n = 10). Out of a total of 17 NA-ATLL cases, 8 (47.1%) carried CCR4 gene alterations that included in-frame and frameshift indels, as well as nonsense mutations targeted to the C-terminus cytoplasmic tail and also the trans-membrane domain. In subtype analysis, 6 out 14 acute cases (42.9%) and 2 out of 3 (66.7%) of chronic cases carried at least one copy of mutated CCR4 gene, indicating that the mutation frequency in NA-ATLL is possibly even higher than that reported for the Japanese cohorts ( Figure 1). We then evaluated cell surface CCR4 expression using flow cytometry. The primary ATLL cells (CD4 +CD7 -CD8 -) from all 7 diagnostic samples uniformly express markedly increased levels of CCR4 relative to healthy control CD4 T cells. Interestingly, CCR4 expression among 8 ATLL cell lines is highly variable, implying that in vivo, tumor microenvironment factors may also contribute to sustained CCR4 upregulation in addition to the influence from the HTLV-1 oncoprotein, HBZ. FLX475 is an orally active small molecule CCR4 antagonist that is currently in a Phase 1/2 study (NCT03674567) in several types of advanced cancer including EBV+ NK/T cell lymphoma. So far, favorable clinical antitumor activity has been observed that includes complete responses with FLX475 monotherapy and encouraging combination activity (Lin C.-C. et al ESMO-IO 2022 Dec; #187P). Using several CCR4-positive cell lines, we examined in vitro anti-ATLL activity of CCR4-351, a CCR4 antagonist that is a highly related analog of FLX475. CCR4 is the exclusive homing receptor for two chemokine molecules, CCL17 and CCL22. In a transwell assay, both chemokines can elicit strong chemotaxis activity in a J-ATLL cell line ED40515(+). However, only CCL22 but not CCL17 can induce significant chemotaxis in two NA-ATLL cell lines, ATL#13 and ATL#29. The exact cause of this difference between these cell lines awaits future studies. In these transwell-based assays, CCR4-351 exhibited potent chemotaxis inhibitory activity with IC 50 values ranging from 7-60 nM ( Figure 2). In addition, when the cell lines were cultured under growth factor-deprivation conditions, CCR4-351 treatment caused a mild reduction in total cell viability, suggesting an additional anti-ATLL mechanism of action. In summary, in this first study of the CCR4 pathway status in NA-ATLL, we found that nearly half of the cases in our ATLL cohort carried a mutated CCR4 gene. Contrary to primary ATLL cells, ATLL cell lines exhibit a wide variation in CCR4 expression. CCL22 but not CCL17 induced strong chemotaxis behavior in NA-ATLL cell lines, which was potently inhibited by a small molecule CCR4 antagonist, CCR4-351. Since extramedullary presentation is frequently seen in NA-ATLL and central nervous system involvement is an adverse prognostic feature, inhibiting chemotaxis with a CCR4 antagonist such as FLX475 may be an effective therapeutic approach.

Dietary L-Tryptophan consumption determines the number of colonic regulatory T cells and susceptibility to colitis via GPR15

Environmental factors are the major contributor to the onset of immunological disorders such as ulcerative colitis. However, their identities remain unclear. Here, we discover that the amount of consumed L-Tryptophan (L-Trp), a ubiquitous dietary component, determines the transcription level of the colonic T cell homing receptor, GPR15, hence affecting the number of colonic FOXP3+ regulatory T (Treg) cells and local immune homeostasis. Ingested L-Trp is converted by host IDO1/2 enzymes, but not by gut microbiota, to compounds that induce GPR15 transcription preferentially in Treg cells via the aryl hydrocarbon receptor. Consequently, two weeks of dietary L-Trp supplementation nearly double the colonic GPR15+ Treg cells via GPR15-mediated homing and substantially reduce the future risk of colitis. In addition, humans consume 3–4 times less L-Trp per kilogram of body weight and have fewer colonic GPR15+ Treg cells than mice. Thus, we uncover a microbiota-independent mechanism linking dietary L-Trp and colonic Treg cells, that may have therapeutic potential.

Multimeric immunotherapeutic complexes activating natural killer cells towards HIV-1 cure

BackgroundCombination antiretroviral therapy (cART) has dramatically extended the life expectancy of people living with HIV-1 and improved their quality of life. There is nevertheless no cure for HIV-1 infection since HIV-1 persists in viral reservoirs of latently infected CD4+ T cells. cART does not eradicate HIV-1 reservoirs or restore cytotoxic natural killer (NK) cells which are dramatically reduced by HIV-1 infection, and express the checkpoint inhibitors NKG2A or KIR2DL upregulated after HIV-1 infection. Cytotoxic NK cells expressing the homing receptor CXCR5 were recently described as key subsets controlling viral replication.MethodsWe designed and evaluated the potency of “Natural killer activating Multimeric immunotherapeutic compleXes”, called as NaMiX, combining multimers of the IL-15/IL-15Rα complex with an anti-NKG2A or an anti-KIR single-chain fragment variable (scFv) to kill HIV-1 infected CD4+ T cells. The oligomerization domain of the C4 binding protein was used to associate the IL-15/IL-15Rα complex to the scFv of each checkpoint inhibitor as well as to multimerize each entity into a heptamer (α form) or a dimer (β form). Each α or β form was compared in different in vitro models using one-way ANOVA and post-hoc Tukey’s tests before evaluation in humanized NSG tg-huIL-15 mice having functional NK cells.ResultsAll NaMiX significantly enhanced the cytolytic activity of NK and CD8+ T cells against Raji tumour cells and HIV-1+ ACH-2 cells by increasing degranulation, release of granzyme B, perforin and IFN-γ. Targeting NKG2A had a stronger effect than targeting KIR2DL due to higher expression of NKG2A on NK cells. In viral inhibition assays, NaMiX initially increased viral replication of CD4+ T cells which was subsequently inhibited by cytotoxic NK cells. Importantly, anti-NKG2A NaMiX enhanced activation, cytotoxicity, IFN-γ production and CXCR5 expression of NK cells from HIV-1 positive individuals. In humanized NSG tg-huIL-15 mice, we confirmed enhanced activation, degranulation, cytotoxicity of NK cells, and killing of HIV-1 infected cells from mice injected with the anti-NKG2A.α NaMiX, as compared to control mice, as well as decreased total HIV-1 DNA in the lung.ConclusionsNK cell-mediated killing of HIV-1 infected cells by NaMiX represents a promising approach to support HIV-1 cure strategies.

Improved Leukemia Clearance After Adoptive Transfer of NK Cells Expressing the Bone Marrow Homing Receptor CXCR4R334X.

Improved Leukemia Clearance After Adoptive Transfer of NK Cells Expressing the Bone Marrow Homing Receptor CXCR4R334X.

Dysregulated Immunity to Clostridioides difficile in IBD Patients Without a History of Recognized Infection.

Clostridioides difficile is a toxin-secreting bacteria that is an urgent antimicrobial resistance threat, with approximately 25% of patients developing recurrent infections. Inflammatory bowel disease (IBD) patients are at increased risk of severe, recurrent C. difficile infection. To investigate a role for C. difficile infection in IBD pathogenesis, we collected peripheral blood and stool from 20 each of ulcerative colitis patients, Crohn's disease patients, and healthy control subjects. We used a flow cytometric activation induced marker assay to quantify C. difficile toxin-specific CD4+ T cells and 16S ribosomal RNA sequencing to study microbiome diversity. We found IBD patients had significantly increased levels of C. difficile toxin B-specific CD4+ T cells, but not immunoglobulin G or immunoglobulin A, compared with healthy control subjects. Within antigen-specific CD4+ T cells, T helper type 17 cells and cells expressing the gut homing receptor integrin β7 were reduced compared with healthy control subjects, similar to our previous study of non-IBD patients with recurrent C. difficile infection. Stool microbiome analysis revealed that gut homing, toxin-specific CD4+ T cells negatively associated with microbial diversity and, along with T helper type 17 cells, positively associated with bacteria enriched in healthy control subjects. These data suggest that IBD patients, potentially due to underlying intestinal dysbiosis, experience undiagnosed C. difficile infections that result in impaired toxin-specific immunity. This may contribute to the development of inflammatory T cell responses toward commensal bacteria and provide a rationale for C. difficile testing in IBD patients.

Peripheral T Cell Populations are Differentially Affected in Familial Mediterranean Fever, Chronic Granulomatous Disease, and Gout

Both innate errors of immunity, such as familial Mediterranean fever (FMF) and chronic granulomatous disease (CGD), and the common inflammatory disease gout are characterized by episodes of sterile inflammatory attacks in the absence of an infection. While these disorders encompass distinct pathologies due to differentially affected metabolic pathways and inflammasome activation mechanisms, their common features are the excessive production of interleukin (IL)-1ß and innate immune cell hyperreactivity. On the other hand, the role of T cells and innate-like lymphocytes such as gamma delta (γδ) T cells in these pathologies is ill-defined. In order to widen our understanding of T cell involvement in CGD, FMF and gout pathology, we developed multicolour immunophenotyping panels for flow cytometry to characterize γδ T cells as well as CD4 and CD8 T cell populations in terms of their cytokine production, activation status, memory or naive phenotypes, exhaustion status, homing receptor expression, and cytotoxic activity. Our study is the first deep immunophenotyping analysis of T cell populations in CGD, FMF, and gout patients. We found that CGD affects the frequencies and activation status of T cells, while gout impairs the cytokine production capacity of Vδ2 T cells. FMF was characterized by decreased percentages of regulatory T cells in circulation and attenuated IFN-γ production capacity by Vδ2 T cells. Autoinflammatory syndromes and congenital defects of phagocyte differentially affect T cell compartments. Future studies are warranted to assess whether these phenotypical changes are relevant for disease pathology.

Modulation of homing receptors on MDSCS and TREGS augments existing inflammation

Modulation of homing receptors on MDSCS and TREGS augments existing inflammation

Food sensitized pediatric patients show colonic cow's milk protein-specific Th2 cells.

Food allergies have become a health concern worldwide. Around 6-10% of children are allergic to cow´s milk proteins. We have previously characterized colorectal polyps in patients sensitized to food allergens. These polyps are classified as inflammatory and present a Th2 environment, with elevated IL-13 and IL-4 and are a site of IgE synthesis. In this study, we characterized and isolated cow´s milk protein-specific T cell lines and T cell clones from the lamina propria of polyps from patients sensitized to these proteins. Isolated T cells responded to cow´s milk proteins similarly to peripheral blood T cells, showing antigen-specific cell proliferation and Th2 cytokines release in vitro. T cell clones obtained were all CD4+ T cells and expressed the membrane TCRαβ receptor and secreted higher IL-4, IL-5 and IL-13 amounts than unstimulated cells, whereas IFN-γ secretion remained unchanged. Remarkably, the gut homing chemokine receptor CCR9 was augmented in cow's milk-specific peripheral and lamina propria T cells, and CCL25 was found to be expressed in the inflammatory polyp tissue and not in the adjacent mucosa. In conclusion, we isolated and characterized cow´s milk-specific lamina propria CD4+ Th2 cells from colonic inflammatory polyps. CCR9 expression on these cells, along with increase secretion of CCL25 in the polyp, favor recruitment and cow's milk specific allergic response within the inflammatory polyp tissue. Our findings may be critical to understand the underlying mechanism that promotes IgE synthesis in the colon of cow´s milk proteins allergic patients, contributing to the development of novel T cell-targeted immunotherapies.

IRF4 is required for migration of CD4+ T cells to the intestine but not for Th2 and Th17 cell maintenance.

The transcription factor Interferon Regulatory Factor 4 (IRF4) is central in control of T cell activation and differentiation. Deficiency of IRF4 results in severe immune deficiency and affects maturation and function of most if not all T cell subsets. Here we use mouse infection models for Citrobacter rodentium and Strongyloides ratti to analyze the function of IRF4 in T helper (Th) 17 and Th2 cell responses, respectively. IRF4 deficient mice were impaired in the control of both pathogens, failed to mount Th17 and Th2 cell responses and showed impaired recruitment of T helper cells to the intestine, the infection site of both pathogens. Compromised intestinal migration was associated with reduced expression of the intestinal homing receptors α4β7 integrin, CCR9 and GPR15. Identification of IRF4 binding sites in the gene loci of these receptors suggests a direct control of their expression by IRF4. Competitive T cell transfer assays further demonstrated that loss of one functional Irf4 allele already affected intestinal accumulation and Th2 and Th17 cell generation, indicating that lower IRF4 levels are of disadvantage for Th2 and Th17 cell differentiation as well as their migration to the intestine. Conversion of peripheral CD4+ T cells from an Irf4 wildtype to an Irf4 heterozygous or from an Irf4 heterozygous to a homozygous mutant genotype after C. rodentium or S. ratti infection did not reduce their capacity to produce Th17 or Th2 cytokines and only partially affected their persistence in the intestine, revealing that IRF4 is not essential for maintenance of the Th2 and Th17 phenotype and for survival of these T helper cells in the intestine. In conclusion, we demonstrate that the expression levels of IRF4 determine Th2 and Th17 cell differentiation and their intestinal accumulation but that IRF4 expression is not crucial for Th2 and Th17 cell survival.