Anti-cancer pro-inflammatory effects of an IgE antibody targeting the melanoma-associated antigen chondroitin sulfate proteoglycan 4.

Outcomes for half of patients with melanoma remain poor despite standard-of-care checkpoint inhibitor therapies. The prevalence of the melanoma-associated antigen chondroitin sulfate proteoglycan 4 (CSPG4) expression is ~70%, therefore effective immunotherapies directed at CSPG4 could benefit many patients. Since IgE exerts potent immune-activating functions in tissues, we engineer a monoclonal IgE antibody with human constant domains recognizing CSPG4 to target melanoma. CSPG4 IgE binds to human melanomas including metastases, mediates tumoricidal antibody-dependent cellular cytotoxicity and stimulates human IgE Fc-receptor-expressing monocytes towards pro-inflammatory phenotypes. IgE demonstrates anti-tumor activity in human melanoma xenograft models engrafted with human effector cells and is associated with enhanced macrophage infiltration, enriched monocyte and macrophage gene signatures and pro-inflammatory signaling pathways in the tumor microenvironment. IgE prolongs the survival of patient-derived xenograft-bearing mice reconstituted with autologous immune cells. No ex vivo activation of basophils in patient blood is measured in the presence of CSPG4 IgE. Our findings support a promising IgE-based immunotherapy for melanoma.

Folate receptor alpha in ovarian cancer tissue and patient serum is associated with disease burden and treatment outcomes.

BACKGROUND: Survival rates for ovarian cancer remain poor, and monitoring and prediction of therapeutic response may benefit from additional markers. Ovarian cancers frequently overexpress Folate Receptor alpha (FRα) and the soluble receptor (sFRα) is measurable in blood. Here we investigated sFRα as a potential biomarker. METHODS: We evaluated sFRα longitudinally, before and during neo-adjuvant, adjuvant and palliative therapies, and tumour FRα expression status by immunohistrochemistry. The impact of free FRα on the efficacy of anti-FRα treatments was evaluated by an antibody-dependent cellular cytotoxicity assay. RESULTS: Membrane and/or cytoplasmic FRα staining were observed in 52.7% tumours from 316 ovarian cancer patients with diverse histotypes. Circulating sFRα levels were significantly higher in patients, compared to healthy volunteers, specifically in patients sampled prior to neoadjuvant and palliative treatments. sFRα was associated with FRα cell membrane expression in the tumour. sFRα levels decreased alongside concurrent tumour burden in patients receiving standard therapies. High concentrations of sFRα partly reduced anti-FRα antibody tumour cell killing, an effect overcome by increased antibody doses. CONCLUSIONS: sFRα may present a non-invasive marker for tumour FRα expression, with the potential for monitoring patient response to treatment. Larger, prospective studies should evaluate FRα for assessing disease burden and response to systemic treatments.

Ligelizumab impairs IgE-binding to plasmacytoid dendritic cells more potently than omalizumab and restores IFN-α production and FOXP3+ Treg generation.

BACKGROUND: Ligelizumab is an anti-IgE monoclonal antibody binding IgE with higher affinity than omalizumab that is under clinical investigation for several IgE-mediated diseases. We previously showed that omalizumab removes IgE bound to FcεRI on plasmacytoid dendritic cells (pDCs) and restores their ability to produce IFN-α and regulatory T cells (Tregs). The aim of this work is to investigate the capacity of ligelizumab to regulate functional properties of pDCs in comparison with omalizumab. METHODS: pDCs were isolated from atopic donors and IgE was detached from FcεRI on pDCs with designed ankyrin repeat protein (DARPin) bi53-79. pDCs were resensitized with IgE alone or in the presence of ligelizumab or omalizumab prior to IgE-FcεRI crosslinking and Toll-like receptor 9 (TLR9) stimulation. Flow cytometry, ELISA, coculture experiments and intranuclear staining were performed to determine cytokine production and Treg generation. An antigen-specific model of resensitization and IgE-crosslinking was also performed. RESULTS: The levels of serum total free IgE show a non-linear positive correlation with the frequency of IgE+ pDCs displaying IgE bound to FcεRI within the 43 individual donors included in the study. Ligelizumab displays stronger capacity than omalizumab to block the binding of free IgE to FcεRI on human pDCs, resulting in a greater restoration of TLR9-L-induced IFN-α production. Ligelizumab also restores the ability of pDCs to generate FOXP3+ Tregs as previously reported for omalizumab. CONCLUSIONS: The uncovered novel molecular mechanisms of ligelizumab to regulate functional properties of pDCs from atopic donors might have important clinical implications for anti-IgE treatments in different IgE-mediated diseases.

Cannabinoids induce functional Tregs by promoting tolerogenic DCs via autophagy and metabolic reprograming.

The generation of functional regulatory T cells (Tregs) is essential to keep tissue homeostasis and restore healthy immune responses in many biological and inflammatory contexts. Cannabinoids have been pointed out as potential therapeutic tools for several diseases. Dendritic cells (DCs) express the endocannabinoid system, including the cannabinoid receptors CB1 and CB2. However, how cannabinoids might regulate functional properties of DCs is not completely understood. We uncover that the triggering of cannabinoid receptors promote human tolerogenic DCs that are able to prime functional FOXP3+ Tregs in the context of different inflammatory diseases. Mechanistically, cannabinoids imprint tolerogenicity in human DCs by inhibiting NF-κB, MAPK and mTOR signalling pathways while inducing AMPK and functional autophagy flux via CB1- and PPARα-mediated activation, which drives metabolic rewiring towards increased mitochondrial activity and oxidative phosphorylation. Cannabinoids exhibit in vivo protective and anti-inflammatory effects in LPS-induced sepsis and also promote the generation of FOXP3+ Tregs. In addition, immediate anaphylactic reactions are decreased in peanut allergic mice and the generation of allergen-specific FOXP3+ Tregs are promoted, demonstrating that these immunomodulatory effects take place in both type 1- and type 2-mediated inflammatory diseases. Our findings might open new avenues for novel cannabinoid-based interventions in different inflammatory and immune-mediated diseases.

Insights from IgE Immune Surveillance in Allergy and Cancer for Anti-Tumour IgE Treatments.

IgE, the predominant antibody class of the allergic response, is known for its roles in protecting against parasites; however, a growing body of evidence indicates a significant role for IgE and its associated effector cells in tumour immunosurveillance, highlighted by the field of AllergoOncology and the successes of the first-in-class IgE cancer therapeutic MOv18. Supporting this concept, substantial epidemiological data ascribe potential roles for IgE, allergy, and atopy in protecting against specific tumour types, with a corresponding increased cancer risk associated with IgE immunodeficiency. Here, we consider how epidemiological data in combination with functional data reveals a complex interplay of IgE and allergy with cancer, which cannot be explained solely by one of the existing conventional hypotheses. We furthermore discuss how, in turn, such data may be used to inform future therapeutic approaches, including the clinical management of different patient groups. With epidemiological findings highlighting several high-risk cancer types protected against by high IgE levels, it is possible that use of IgE-based therapeutics for a range of malignant indications may offer efficacy to complement that of established IgG-class antibodies.

Immunotherapy using IgE or CAR T cells for cancers expressing the tumor antigen SLC3A2.

BACKGROUND: Cancer immunotherapy with monoclonal antibodies and chimeric antigen receptor (CAR) T cell therapies can benefit from selection of new targets with high levels of tumor specificity and from early assessments of efficacy and safety to derisk potential therapies. METHODS: Employing mass spectrometry, bioinformatics, immuno-mass spectrometry and CRISPR/Cas9 we identified the target of the tumor-specific SF-25 antibody. We engineered IgE and CAR T cell immunotherapies derived from the SF-25 clone and evaluated potential for cancer therapy. RESULTS: We identified the target of the SF-25 clone as the tumor-associated antigen SLC3A2, a cell surface protein with key roles in cancer metabolism. We generated IgE monoclonal antibody, and CAR T cell immunotherapies each recognizing SLC3A2. In concordance with preclinical and, more recently, clinical findings with the first-in-class IgE antibody MOv18 (recognizing the tumor-associated antigen Folate Receptor alpha), SF-25 IgE potentiated Fc-mediated effector functions against cancer cells in vitro and restricted human tumor xenograft growth in mice engrafted with human effector cells. The antibody did not trigger basophil activation in cancer patient blood ex vivo, suggesting failure to induce type I hypersensitivity, and supporting safe therapeutic administration. SLC3A2-specific CAR T cells demonstrated cytotoxicity against tumor cells, stimulated interferon-γ and interleukin-2 production in vitro. In vivo SLC3A2-specific CAR T cells significantly increased overall survival and reduced growth of subcutaneous PC3-LN3-luciferase xenografts. No weight loss, manifestations of cytokine release syndrome or graft-versus-host disease, were detected. CONCLUSIONS: These findings identify efficacious and potentially safe tumor-targeting of SLC3A2 with novel immune-activating antibody and genetically modified cell therapies.

The Presence of a Marked Imbalance Between Regulatory T Cells and Effector T Cells Reveals That Tolerance Mechanisms Could Be Compromised in Heart Transplant Children.

Regulatory T cells (Treg) are crucial for the induction and maintenance of graft tolerance. In pediatric heart transplant procedures, the thymus is routinely excised, removing the primary source of T-cell replenishment. Consequently, thymectomy joined to the effects of immunosuppression on the T-cell compartment may have a detrimental impact on Treg values, compromising the intrinsic tolerance mechanisms and the protective role of Treg preventing graft rejection in heart transplant children. METHODS: A prospective study including 7 heart transplant children was performed, and immune cell populations were evaluated periodically in fresh peripheral blood at different time points before and up to 3 y posttransplant. RESULTS: Treg counts decreased significantly from the seventh-month posttransplant. Furthermore, there was a significant increase in effector memory and terminally differentiated effector memory T cells coinciding with the fall of Treg counts. The Treg/Teffector ratio, a valuable marker of the tolerance/rejection balance, reached values around 90% lower than pretransplant values. Additionally, a negative correlation between Treg count and T effector frequency was observed. Particularly, when Treg count decreases below 50 or 75 cells/µL in the patients, the increase in the frequency of T effector CD4+ and CD8+, respectively, experiences a tipping point, and the proportion of T-effector cells increases dramatically. CONCLUSIONS: These results reveal that interventions employed in pediatric heart transplantation (immunosuppression and thymectomy) could induce, as an inevitable consequence, a dysregulation in the immunologic status characterized by a marked imbalance between Treg and T effector, which could jeopardize the preservation of tolerance during the period with the higher incidence of acute rejection.

Basiliximab impairs regulatory T cell (TREG) function and could affect the short-term graft acceptance in children with heart transplantation.

CD25, the alpha chain of the IL-2 receptor, is expressed on activated effector T cells that mediate immune graft damage. Induction immunosuppression is commonly used in solid organ transplantation and can include antibodies blocking CD25. However, regulatory T cells (Tregs) also rely on CD25 for their proliferation, survival, and regulatory function. Therefore, CD25-blockade may compromise Treg protective role against rejection. We analysed in vitro the effect of basiliximab (BXM) on the viability, phenotype, proliferation and cytokine production of Treg cells. We also evaluated in vivo the effect of BXM on Treg in thymectomized heart transplant children receiving BXM in comparison to patients not receiving induction therapy. Our results show that BXM reduces Treg counts and function in vitro by affecting their proliferation, Foxp3 expression, and IL-10 secretion capacity. In pediatric heart-transplant patients, we observed decreased Treg counts and a diminished Treg/Teff ratio in BXM-treated patients up to 6-month after treatment, recovering baseline values at the end of the 12-month follow up period. These results reveal that the use of BXM could produce detrimental effects on Tregs, and support the evidence suggesting that BXM induction could impair the protective role of Tregs in the period of highest incidence of acute graft rejection.

Massive application of the SARS-CoV-2 diagnostic test: simulation of its effect on the evolution of the epidemic in Spain.

In Spain, the epidemic curve caused by COVID-19 has reached its peak in the last days of March. The implementation of the blockade derived from the declaration of the state of alarm on 14th March has raised a discussion on how and when to deal with the unblocking. In this paper, we intend to add information that may help by using epidemic simulation techniques with stochastic individual contact models and several extensions.

The Role of Cannabinoids in Allergic Diseases: Collegium Internationale Allergologicum (CIA) Update 2020.

The human endocannabinoid system (ECS) is a complex signalling network involved in many key physiological processes. The ECS includes the cannabinoid receptors, the endocannabinoid ligands, and the enzymes related to their synthesis and degradation. Other cannabinoids encompass the phytocannabinoids from Cannabis sativaL.(marijuana) and the synthetic cannabinoids. Alterations in the ECS are associated with different diseases, including inflammatory and immune-mediated disorders such as allergy. Allergy is a global health problem of increasing prevalence with high socio-economic impact. Different studies have convincingly demonstrated that cannabinoids play a role in allergy, but their actual contribution is still controversial. It has been shown that cannabinoids exert anti-inflammatory properties in the airways and the skin of allergic patients. Other studies reported that cannabinoids might exacerbate asthma and atopic dermatitis mainly depending on CB2-mediated signalling pathways. A better understanding of the molecular mechanisms involved in the mode of action of specific cannabinoids and cannabinoid receptors on relevant immune cells under different biological contexts might well contribute to the design of novel strategies for the prevention and treatment of allergic diseases. Future research in this promising emerging field in the context of allergy is warranted for the upcoming years.

Analysis of the dysregulation between regulatory B and T cells (Breg and Treg) in human immunodeficiency virus (HIV)-infected patients.

This study examines the relationship between regulatory B (Breg) and T (Treg) compartments, which play crucial roles in the maintenance of immune homeostasis in the context of HIV. Using flow cytometry, the phenotypes of different Breg and Treg subsets from HIV-infected and healthy individuals were analyzed, along with the suppressive capacity of Breg. Peripheral blood samples of thirteen HIV+ treatment-naïve individuals, fourteen treated-HIV+ individuals with undetectable viral load and twelve healthy individuals were analyzed. The absolute counts of Breg and Treg subsets were decreased in HIV+ treatment-naïve individuals in comparison to treated-HIV+ and healthy individuals. Interestingly, correlations between Breg subsets (CD24hiCD27+ and PD-L1+ B cells) and IL-10-producing Breg observed in healthy individuals were lost in HIV+ treatment-naïve individuals. However, a correlation between frequencies of CD24hiCD38hi or TIM-1+-Breg subsets and Treg was observed in HIV+ treatment-naïve individuals and not in healthy individuals. Therefore, we hypothesized that various Breg subsets might have different functions during B and T-cell homeostasis during HIV-1 infection. In parallel, stimulated Breg from HIV-infected treatment-naïve individuals presented a decreased ability to suppress CD4+ T-cell proliferation in comparison to the stimulated Breg from treated-HIV+ or healthy individuals. We demonstrate a dysregulation between Breg and Treg subsets in HIV-infected individuals, which might participate in the hyper-activation and exhaustion of the immune system that occurs in such patients.

Immune dysregulation and Th2 polarization are associated with atopic dermatitis in heart-transplant children: A delicate balance between risk of rejection or atopic symptoms.

Atopic dermatitis (AD) has a high incidence in heart-transplant children, and the reason why there is more AD after transplantation is still unknown. We conducted a cross-sectional study comparing 11 AD and 11 non-AD age-matched heart-transplant children, to assess which immune alterations are related to AD in these patients. AD patients had been transplanted at a younger age compared to non-AD, indicating that age at transplant may be determinant in the onset of AD. The earlier thymectomy in AD heart-transplant children favored the presence of more differentiated phenotypes in the T cell compartment. We observed a clear reduction in the T-helper 1/T-helper 2 (Th1/Th2) ratio in AD children. This Th2 polarization was related to eosinophilia and high immunoglobulin E levels, but also to an impaired regulatory T cell (Treg) suppression, which could be secondary to an exhaustion of the Treg compartment. Interestingly, AD patients were free of rejection episodes (0/11) in comparison to non-AD children (4/11). We propose that a predominant Th2 phenotype may prevent the emergence of Th1 responses associated with graft rejection. A more differentiated Treg phenotype could also play a role in preventing acute rejection in the first year posttransplant. Our findings provide useful insights and knowledge for the better understanding of atopic disorders in transplanted children.

CD72/CD100 and PD-1/PD-L1 markers are increased on T and B cells in HIV-1+ viremic individuals, and CD72/CD100 axis is correlated with T-cell exhaustion.

In our work, we analyzed the role of the CD100/CD72 and PD-1/PD-L1 axes in immune response dysfunction in human immunodeficiency virus (HIV)-1 infection in which high expressions of PD-1 and PD-L1 were associated with an immunosuppressive state via limitation of the HIV-1-specific T-cell responses. CD100 was demonstrated to play a relevant role in immune responses in various pathological processes and may be responsible for immune dysregulation during HIV-1 infection. We investigated the function of CD72/CD100, and PD-1/PDL-1 axes on T and B cells in HIV-infected individuals and in healthy individuals. We analyzed the frequencies and fluorescence intensities of these four markers on CD4+, CD8+ T and B cells. Marker expressions were increased during active HIV-1 infection. CD100 frequency on T cells was positively associated with the expression of PD-1 and PD-L1 on T cells from HIV-infected treatment-naïve individuals. In addition, the frequency of CD72-expressing T cells was associated with interferon gamma (IFN-γ) production in HIV-infected treatment-naïve individuals. Our data suggest that the CD72/CD100 and PD-1/PD-L1 axes may jointly participate in dysregulation of immunity during HIV-1 infection and could partially explain the immune systems' hyper-activation and exhaustion.

Corrigendum: Functional Mechanisms of Treg in the Context of HIV Infection and the Janus Face of Immune Suppression.

[This corrects the article on p. 192 in vol. 7, PMID: 27242797.].

Human immunodeficiency virus type-1 induces a regulatory B cell-like phenotype in vitro.

Individuals infected with human immunodeficiency virus type-1 (HIV-1) usually show a general dysregulation and hyper-activation of the immune system. A direct influence of HIV-1 particles on B-cell phenotypes and functions has been previously described. However, the consequences of B-cell dysregulation are still poorly understood. We evaluated the phenotypic changes in primary B cells after direct contact with HIV-1 particles in comparison with different types of stimuli. The functionality of treated B cells was challenged in co-culture experiments with autologous CD4+ and CD8+ T cells. We demonstrated that HIV-1 induces a phenotypic change in B cells towards a regulatory B-cell phenotype, showing a higher level of IL-10, TGF-ß1, EBI3 or IL-12(p35) mRNA expression and acquiring an immunosuppressive profile. The acquisition of a Breg phenotype was confirmed by co-culture experiments where HIV-treated B cells reduced the proliferation and the TNFα production of CD4+ or CD8+ T cells. This suppressive ability of HIV-treated B cells was dependent on cell-to-cell contact between these B cells and effector cells. To our knowledge, these data provide the first evidence that HIV-1 can directly induce a regulatory B cell-like immunosuppressive phenotype, which could have the ability to impair specific immune responses. This dysregulation could constitute one of the mechanisms underlying unsuccessful efforts to develop an efficient vaccine against HIV-1.

The establishment of cow's milk protein allergy in infants is related with a deficit of regulatory T cells (Treg) and vitamin D.

BACKGROUND: Cow's milk protein allergy (CMPA) is the most common food allergy in infants. However, little is known about which specific immune mechanisms are related with the CMPA onset. The objective was to investigate which immune alterations constitute differential factors between allergy and tolerance, and hence could be implicated in the CMPA establishment in infants. METHODS: An extensive analysis of immune subsets, including Treg and cytokine-secreting cells was performed in blood samples from 28 infants younger than 9 mo obtained 1-4 d after the first adverse reaction to milk. RESULTS: Less than 4 d after first allergic reaction, infants who developed CMPA had decreased Treg counts and increased frequency of IL4-secreting CD4 T cells compared to controls. The deficit of Tregs was correlated with decreased serum levels of vitamin D. Values of Tregs, IL4-secreting cells and vitamin D were good predictors of CMPA diagnosis. Basal vitamin D levels in CMPA infants also predicted those CMPA patients developing spontaneous tolerance in the first year. CONCLUSION: Establishment of CMPA in infants was related with lower Treg and vitamin D levels. These immune alterations would be crucial factors behind the CMPA establishment and they could constitute a therapeutic target for treatment of CMPA.

Functional Mechanisms of Treg in the Context of HIV Infection and the Janus Face of Immune Suppression.

Regulatory T cells (Tregs) play an important role in infections, by modulating host immune responses and avoiding the overreactive immunity that in the case of human immunodeficiency virus (HIV) infection leads to a marked erosion and deregulation of the entire immune system. Therefore, the suppressive function of Treg in HIV-infected patients is critical because of their implication on preventing the immune hyperactivation, even though it could also have a detrimental effect by suppressing HIV-specific immune responses. In recent years, several studies have shown that HIV-1 can directly infect Treg, disturbing their phenotype and suppressive capacity via different mechanisms. These effects include Foxp3 and CD25 downregulation, and the impairment of suppressive capacity. This review describes the functional mechanisms of Treg to modulate immune activation during HIV infection, and how such control is no longer fine-tune orchestrated once Treg itself get infected. We will review the current knowledge about the HIV effects on the Treg cytokine expression, on pathways implying the participation of different ectoenzymes (i.e., CD39/CD73 axis), transcription factors (ICER), and lastly on cyclic adenosine monophosphate (cAMP), one of the keystones in Treg-suppressive function. To define which are the HIV effects upon these regulatory mechanisms is crucial not only for the comprehension of immune deregulation in HIV-infected patients but also for the correct understanding of the role of Tregs in HIV infection.