Immune checkpoint blockade impairs immunosuppressive mechanisms of regulatory T cells in B-cell lymphoma.

In malignant disease, CD4+Foxp3+ regulatory T cells (Tregs) hamper antitumor immune responses and may provide a target for immunotherapy. Although immune checkpoint blockade (ICB) has become an established therapy for several cancer entities including lymphoma, its mechanisms have not been entirely uncovered. Using endogenously arising λ-MYC-transgenic mouse B-cell lymphomas, which can effectively be suppressed by either Treg ablation or ICB, we investigated which mechanisms are used by Tregs to suppress antitumor responses and how ICB affects these pathways. During tumor development, Tregs up-regulated Foxp3, CD25, CTLA-4 and IL-10, which correlated with enhanced immunosuppressive functions. Thus, in contrast to other tumors, Tregs did not become dysfunctional despite chronic stimulation in the tumor microenvironment and progressive up-regulation of PD-1. Immunosuppression was mediated by direct contacts between Tregs and effector T cells and by IL-10. When λ-MYC mice were treated with ICB antibodies, Tregs revealed a less profound up-regulation of Foxp3, CD25 and IL-10 and a decreased suppressive capacity. This may be due to the shift towards a pro-inflammatory milieu fostered by ICB. In summary, an ICB-induced interference with Treg-dependent immunosuppression may contribute to the success of ICB.

Cystic Fibrosis Newborn Screening in Austria Using PAP and the Numeric Product of PAP and IRT Concentrations as Second-Tier Parameters.

In Austria, newborns have been screened for cystic fibrosis (CF) by analyzing immunoreactive trypsinogen (IRT) from dried blood spots (DBS)s for nearly 20 years. Recently, pancreatitis-associated protein (PAP) analysis was introduced as a second-tier test with the aim of reducing recalls for second DBS cards while keeping sensitivity high. For 28 months, when IRT was elevated (65-130 ng/mL), PAP was measured from the first DBS (n = 198,927) with a two-step cut-off applied. For the last 12 months of the observation period (n = 85,421), an additional IRT×PAP cut-off was introduced. If PAP or IRT×PAP were above cut-off, a second card was analyzed for IRT and in case of elevated values identified as screen-positive. Above 130 ng/mL IRT in the first DBS, newborns were classified as screen-positive. IRT analysis of first DBS resulted in 1961 (1%) tests for PAP. In the first 16 months, 26 of 93 screen-positive were confirmed to have CF. Two false-negatives have been reported (sensitivity = 92.8%). Importantly, less than 30% of families compared to the previous IRT-IRT screening scheme had to be contacted causing distress. Adding IRT×PAP caused a marginally increased number of second cards and sweat tests to be requested during this period (15 and 3, respectively) compared to the initial IRT-PAP scheme. One case of confirmed CF was found due to IRT×PAP, demonstrating an increase in sensitivity. Thus, the relatively simple and economical algorithm presented here performs effectively and may be a useful model for inclusion of CF into NBS panels or modification of existing schemes.

Interleukin-10 counteracts T-helper type 1 responses in B-cell lymphoma and is a target for tumor immunotherapy.

To establish strategies for immunotherapy of B-cell lymphoma, it is mandatory to gain deeper insights into the mechanisms of tumor immune escape. In a mouse model of endogenously arising lymphoma, we investigated the impact of IL-10 on the regulation of antitumor responses. Despite progressive functional impairment of NK cells and lack of IFN-γ in the tumor milieu, we found an augmented fraction of T helper type 1 (Th1) cells, which continued to express IFN-γ but also upregulated IL-10 during disease development. Using a lymphoma microenvironment in vitro, we showed that Th1 cells were converted to Foxp3-negative T regulatory type 1 (Tr1) cells, which coexpressed IFN-γ and IL-10 and upregulated PD-1. This differentiation required pre-existing IL-10, which was primarily provided by malignant B cells and dendritic cells. IFN-γ only declined in cells with the uppermost PD-1 levels. Importantly, antibody-mediated IL-10 ablation in vivo improved effector cell functions and significantly suppressed tumor development. While the contribution of IL-10 to cancer immune escape has been controversially discussed in the past, we show that IL-10 suppresses ongoing, potentially protective immune responses in lymphoma and might be a target for immunotherapy.

Therapy of lymphoma by immune checkpoint inhibitors: the role of T cells, NK cells and cytokine-induced tumor senescence.

BACKGROUND: Although antibodies blocking immune checkpoints have already been approved for clinical cancer treatment, the mechanisms involved are not yet completely elucidated. Here we used a λ-MYC transgenic model of endogenously growing B-cell lymphoma to analyze the requirements for effective therapy with immune checkpoint inhibitors. METHODS: Growth of spontaneous lymphoma was monitored in mice that received antibodies targeting programmed cell death protein 1 and cytotoxic T lymphocyte-associated protein-4, and the role of different immune cell compartments and cytokines was studied by in vivo depletion experiments. Activation of T and natural killer cells and the induction of tumor senescence were analyzed by flow cytometry. RESULTS: On immune checkpoint blockade, visible lymphomas developed at later time points than in untreated controls, indicating an enhanced tumor control. Importantly, 20% to 30% of mice were even long-term protected and did never develop clinical signs of tumor growth. The therapeutic effect was dependent on cytokine-induced senescence in malignant B cells. The proinflammatory cytokines interferon-γ (IFN-γ) and tumor necrosis factor (TNF) were necessary for the survival benefit as well as for senescence induction in the λ-MYC model. Antibody therapy improved T-cell functions such as cytokine production, and long-time survivors were only observed in the presence of T cells. Yet, NK cells also had a pronounced effect on therapy-induced delay of tumor growth. Antibody treatment enhanced numbers, proliferation and IFN-γ expression of NK cells in developing tumors. The therapeutic effect was fully abrogated only after depletion of both, T cells and NK cells, or after ablation of either IFN-γ or TNF. CONCLUSIONS: Tumor cell senescence may explain why patients responding to immune checkpoint blockade frequently show stable growth arrest of tumors rather than complete tumor regression. In the lymphoma model studied, successful therapy required both, tumor-directed T-cell responses and NK cells, which control, at least partly, tumor development through cytokine-induced tumor senescence.

The role of dendritic cells for therapy of B-cell lymphoma with immune checkpoint inhibitors.

Immune checkpoint blocking (ICB) is a promising new tool of cancer treatment. Yet, the underlying therapeutic mechanisms are not fully understood. Here we investigated the role of dendritic cells (DCs) for the therapeutic effect of ICB in a λ-MYC-transgenic mouse model of endogenously arising B-cell lymphoma. The growth of these tumors can be effectively delayed by antibodies against CTLA-4 and PD-1. Tumor-infiltrating DCs from mice having received therapy showed an upregulation of costimulatory molecules as well as an augmented IL-12/IL-10 ratio as compared to untreated controls. Both alterations seemed to be induced by interferon-γ (IFN-γ), which is upregulated in T cells and natural killer cells upon ICB. Furthermore, the enhanced IL-12/IL-10 ratio, which favors Th1-prone antitumor T-cell responses, was a consequence of direct interaction of ICB antibodies with DCs. Importantly, the capability of tumor-infiltrating DCs of stimulating peptide-specific or allogeneic T-cell responses in vitro was improved when DCs were derived from ICB-treated mice. The data indicate that ICB therapy is not only effective by directly activating T cells, but also by triggering a complex network, in which DCs play a pivotal role at the interface between innate and adaptive antitumor responses.

Regulatory T Cells in an Endogenous Mouse Lymphoma Recognize Specific Antigen Peptides and Contribute to Immune Escape.

Foxp3+ regulatory T cells (Tregs) sustain immune homeostasis and may contribute to immune escape in malignant disease. As a prerequisite for developing immunologic approaches in cancer therapy, it is necessary to understand the ontogeny and the antigenic specificities of tumor-infiltrating Tregs. We addressed this question by using a λ-MYC transgenic mouse model of endogenously arising B-cell lymphoma, which mirrors key features of human Burkitt lymphoma. We show that Foxp3+ Tregs suppress antitumor responses in endogenous lymphoma. Ablation of Foxp3+ Tregs significantly delayed tumor development. The ratio of Treg to effector T cells was elevated in growing tumors, which could be ascribed to differential proliferation. The Tregs detected were mainly natural Tregs that apparently recognized self-antigens. We identified MHC class II-restricted nonmutated self-epitopes, which were more prevalent in lymphoma than in normal B cells and could be recognized by Tregs. These epitopes were derived from proteins that are associated with cellular processes related to malignancy and may be overexpressed in the tumor.

Breastfeeding and mucosal and cutaneous colonization by Staphylococcus aureus in atopic children.

BACKGROUND: Studies on the effects of breastfeeding on the development of Atopic Dermatitis (AD) have shown controversial results. The importance of this condition deserves further studies; in particular, it remains unclear whether colonization of atopic patients by Staphylococcus aureus (S. aureus) through breastfeeding is relevant to the development of AD. OBJECTIVE: To examine the potential relation between breastfeeding and colonization by S. aureus in atopic patients. METHOD: Transversal study of atopic patients, aged from 4 to 24 months, both genders, receiving outpatient care and 72 mothers. Data on infant breastfeeding practices and on clinical-epidemiological profile were registered. Swabs of the infants' nares and skin (cubital fossa) and swabs of the mothers' nares were collected. For univariate analysis, X2 (chi-square) and Fischer Exact's test were used. RESULTS: Among breastfed children, S. aureus was isolated from 8 (25.8%) infants' nares swabs and from 4 (12.9%) skin swabs. Among not breastfed children, S. aureus was isolated from 10 (20.8%) infants' nares swabs and from 11 (22.9%) skin swabs. Sixteen mothers (22.2%) had S. aureus isolated from their nares swabs. There was no significant association between breastfeeding and S. aureus colonization (child skin and/or nares). However, there was a degree of concordance for S. aureus carriage among mothers and infants. Among 72 pairs, 56 (77.8%) were concordant. CONCLUSION: Breastfeeding was not associated with S. aureus muco-cutaneous colonization in atopic infants.

Aleitamento materno e colonização mucocutânea pelo Staphylococcus aureus na criança com dermatite atópica / Breastfeeding and mucosal and cutaneous colonization by Staphylococcus aureus in atopic children

FUNDAMENTOS: Não há consenso quanto ao efeito do aleitamento materno no desenvolvimento da dermatite atópica. É necessário aprofundar conhecimentos sobre possíveis fatores envolvidos nessa relação, como a influência do aleitamento materno na colonização do paciente atópico pelo Staphylococcus aureus (S. aureus). OBJETIVO: Avaliar uma potencial associação entre aleitamento materno e colonização pelo S. aureus nas crianças atópicas. MÉTODOS: Estudo transversal envolvendo 79 crianças atópicas de 4-24 meses, de ambos os sexos, em acompanhamento no Ambulatório de Dermatologia Sanitária de Porto Alegre, e 72 mães. Registraram-se dados clinicoepidemiológicos e de alimentação das crianças. Pesquisou-se a presença do S. aureus em swab nasal e cutâneo nas crianças e swab nasal das respectivas mães. Para análise dos dados, realizaram-se os testes qui-quadrado de Pearson e exato de Fischer. RESULTADOS: Entre as crianças amamentadas, S. aureus foi encontrado nas cavidades nasais de oito (25,8 por cento) e na pele (fossas cubitais) de quatro (12,9 por cento). Entre as não amamentadas, encontrou-se S. aureus nas cavidades nasais de dez (20,8 por cento) e na pele de 11 (22,9 por cento). Entre as mães, 16 (22,2 por cento) apresentaram crescimento de S. aureus no material proveniente do swab nasal. Não se observou associação significativa entre aleitamento materno e colonização pelo S. aureus das cavidades nasais ou da pele das crianças. Entretanto, houve concordância entre a colonização pelo S. aureus nas cavidades nasais das mães e nas cavidades nasais e/ou na pele dos filhos. Das 72 duplas, houve concordância em 56 (77,8 por cento). CONCLUSÃO: O aleitamento materno parece não influenciar a colonização mucocutânea pelo S. aureus em crianças com dermatite atópica.

BACKGROUND: Studies on the effects of breastfeeding on the development of Atopic Dermatitis (AD) have shown controversial results. The importance of this condition deserves further studies; in particular, it remains unclear whether colonization of atopic patients by Staphylococcus aureus (S. aureus) through breastfeeding is relevant to the development of AD. OBJECTIVE: To examine the potential relation between breastfeeding and colonization by S. aureus in atopic patients. METHOD: Transversal study of atopic patients, aged from 4 to 24 months, both genders, receiving outpatient care and 72 mothers. Data on infant breastfeeding practices and on clinical-epidemiological profile were registered. Swabs of the infants' nares and skin (cubital fossa) and swabs of the mothers' nares were collected. For univariate analysis, X2 (chi-square) and Fischer Exact's test were used. RESULTS: Among breastfed children, S. aureus was isolated from 8 (25.8 percent) infants' nares swabs and from 4 (12.9 percent) skin swabs. Among not breastfed children, S. aureus was isolated from 10 (20.8 percent) infants' nares swabs and from 11 (22.9 percent) skin swabs. Sixteen mothers (22.2 percent) had S. aureus isolated from their nares swabs. There was no significant association between breastfeeding and S. aureus colonization (child skin and/or nares). However, there was a degree of concordance for S. aureus carriage among mothers and infants. Among 72 pairs, 56 (77.8 percent) were concordant. CONCLUSION: Breastfeeding was not associated with S. aureus muco-cutaneous colonization in atopic infants.