Can atopy have a protective effect against cancer?

Dual Functions of T Lymphocytes in Breast Carcinoma: From Immune Protection to Orchestrating Tumor Progression and Metastasis

Breast cancer (BC) is the most common cancer type in women and the second leading cause of death. Despite recent advances, the mortality rate of BC is still high, highlighting a need to develop new treatment strategies including the modulation of the immune system and immunotherapies. In this regard, understanding the complex function of the involved immune cells and their crosstalk with tumor cells is of great importance. T-cells are recognized as the most important cells in the tumor microenvironment and are divided into several subtypes including helper, cytotoxic, and regulatory T-cells according to their transcription factors, markers, and functions. This article attempts to provide a comprehensive review of the role of T-cell subsets in the prognosis and treatment of patients with BC, and crosstalk between tumor cells and T-cells. The literature overwhelmingly contains controversial findings mainly due to the plasticity of T-cell subsets within the inflammatory conditions and the use of different panels for their phenotyping. However, investigating the role of T-cells in BC immunity depends on a variety of factors including tumor types or subtypes, the stage of the disease, the localization of the cells in the tumor tissue and the presence of different cells or cytokines.

Allergic Rhinitis and Cancer Risk: A Two-Sample Mendelian Randomization Study

Background: There is increasing evidence that allergic rhinitis (AR) is associated with cancer. However, these results are inconsistent. Because of common risk factors, there may be reverse causality and confounding factors that affect our understanding of the relationship between AR and cancer. We aimed to explore the role of AR in cancer development using Mendelian randomization (MR) analysis. Materials and Methods: We performed a two-sample MR analysis using summary data from genome-wide association studies (GWAS). Single nucleotide polymorphisms (SNPs) strongly associated with AR (or hay fever) were used as instrumental variables, mainly using the inverse variance weighted analysis method, supplemented by MR Egger, maximum likelihood, weighted media, and penalized weighted media for MR analysis. Sensitivity analyses included heterogeneity and horizontal pleiotropy; and leave-one-out analyses were performed to test the robustness of our results. Results: MR analysis revealed no evidence of a causal relationship between AR and any of the examined cancers (all p > 0.05). The results using five different analytical approaches were similar. Sensitivity analyses showed no evidence of heterogeneity nor horizontal pleiotropy. According to the leave-one-out sensitivity analyses, no individual SNP was significantly influencing the causal effect of AR on cancers. Conclusions: These findings do not provide evidence to support that AR has a large impact on the risk of eight common cancers in the European population. However, we cannot rule out a very minor effect of AR on cancer. Further large-scale studies are necessary to validate our findings.

Atopic diseases and oncopathology. What do they have in common? A review

The increasing prevalence of cancer worldwide has influenced the interest of researchers to search for factors that may trigger oncogenesis in order to prevent and treat cancer. There is a burning question, can allergic diseases cause or prevent cancer? Numerous epidemiological studies have been conducted that have evaluated aspects of the relationship between allergic diseases and the occurrence of cancers of various localizations. The results of most of these studies are inconsistent, both in the nature of the course of the disease and in the variety of localizations of the occurrence of cancer. In this connection, two basic theories were suggested: the theory of immune surveillance and the theory of inflammation. This review analyzed current scientific work to estimate the incidence of neoplasms against the background of atopic diseases. The analysis of clinical studies shows inconsistent results of the association between allergic diseases and cancer. Several studies an inverse relationship between atopic diseases and cancer risk, which supports the theory of immune surveillance [brain tumor (glioma), pancreatic cancer, colorectal cancer, non-Hodgkin's lymphoma, and breast cancer, cancer of the mouth and throat, larynx]. At the same time, a number of studies note a positive association between atopic diseases and cancer, which confirms the theory of chronic inflammation (lung cancer and colorectal cancer combined with bronchial asthma). The lack of an unequivocal explanation testifies to the urgency of long-term prospective studies aimed at studying the risk factors of cancer in combination with atopic diseases with the subsequent development of risk scale for the purpose of patient stratification, screening, development of early detection programs and new approaches to the treatment of malignant neoplasms.

Air pollution with NO2, PM2.5, and elemental carbon in relation to risk of breast cancer- a nationwide case-control study from Denmark

Air pollution with particulate matter is an established lung carcinogen. Studies have suggested an association with breast cancer, but the evidence is inconsistent.

METHODS

From nationwide registers, we identified all breast cancer cases (n = 55 745) in Denmark between 2000 and 2014. We matched one control for each case on age and year of birth. We used a multi-scale dispersion model to estimate outdoor concentrations of particulate matter <2.5 μm (PM_2.5), elemental carbon (EC) and nitrogen dioxide (NO₂) as time-weighted average over all addresses up to 20 years prior to diagnosis. We calculated odds ratios (OR) and 95% confidence intervals (CI) by conditional logistic regression with adjustment for marital status, educational level, occupational status, personal income, region of origin, medication and area-level socio-economic indicators.

RESULTS

A 10 μg/m³ higher PM_2.5 was associated with an OR for breast cancer of 1.21 (95% CI: 1.11-1.33). The corresponding ORs for EC (per 1 μg/m³) and NO₂ (per 10 μg/m³) were 1.03 (95% CI: 1.00-1.07) and 1.03 (95% CI: 1.01-1.06), respectively. In multi-pollutant models, the OR for PM_2.5 changed only little, whereas ORs for EC or NO₂ approached the null. In an analysis of persons below 55 years, PM_2.5 was associated with an OR of 1.32 (95% CI: 1.09-1.60) per 10 μg/m³ increase.

CONCLUSION

We found evidence of an association between the investigated air pollutants and breast cancer, especially PM_2.5. There were indications that the association differed by age at diagnosis. We were not able to include all potential confounders and thus, results should be interpreted with caution.

Distinct T helper cell-mediated antitumor immunity: T helper 2 cells in focus

The adaptive arm of the immune system is crucial for appropriate antitumor immune responses. It is generally accepted that clusters of differentiation 4+ (CD4+) T cells, which mediate T helper (Th) 1 immunity (type 1 immunity), are the primary Th cell subtype associated with tumor elimination. In this review, we discuss evidence showing that antitumor immunity and better prognosis can be associated with distinct Th cell subtypes in experimental mouse models and humans, with a focus on Th2 cells. The aim of this review is to provide an overview and understanding of the mechanisms associated with different tumor outcomes in the face of immune responses by focusing on the (1) site of tumor development, (2) tumor properties (i. e., tumor metabolism and cytokine receptor expression), and (3) type of immune response that the tumor initially escaped. Therefore, we discuss how low-tolerance organs, such as lungs and brains, might benefit from a less tissue-destructive immune response mediated by Th2 cells. In addition, Th2 cells antitumor effects can be independent of CD8+ T cells, which would circumvent some of the immune escape mechanisms that tumor cells possess, like low expression of major histocompatibility-I (MHC-I). Finally, this review aims to stimulate further studies on the role of Th2 cells in antitumor immunity and briefly discusses emerging treatment options.

CD4+ T helper 2 cells suppress breast cancer by inducing terminal differentiation

Cancer immunology research is largely focused on the role of cytotoxic immune responses against advanced cancers. Herein, we demonstrate that CD4⁺ T helper (Th2) cells directly block spontaneous breast carcinogenesis by inducing the terminal differentiation of the cancer cells. Th2 cell immunity, stimulated by thymic stromal lymphopoietin, caused the epigenetic reprogramming of the tumor cells, activating mammary gland differentiation and suppressing epithelial–mesenchymal transition. Th2 polarization was required for this tumor antigen–specific immunity, which persisted in the absence of CD8⁺ T and B cells. Th2 cells directly blocked breast carcinogenesis by secreting IL-3, IL-5, and GM-CSF, which signaled to their common receptor expressed on breast tumor cells. Importantly, Th2 cell immunity permanently reverted high-grade breast tumors into low-grade, fibrocystic-like structures. Our findings reveal a critical role for CD4⁺ Th2 cells in immunity against breast cancer, which is mediated by terminal differentiation as a distinct effector mechanism for cancer immunoprevention and therapy.

Harnessing the Anti-Tumor Mediators in Mast Cells as a New Strategy for Adoptive Cell Transfer for Cancer

The emergence of cancer immunotherapies utilizing adoptive cell transfer (ACT) continues to be one of the most promising strategies for cancer treatment. Mast cells (MCs) which occur throughout vascularized tissues, are most commonly associated with Type I hypersensitivity, bind immunoglobin E (IgE) with high affinity, produce anti-cancer mediators such as tumor necrosis factor alpha (TNF-α) and granulocyte macrophage colony-stimulating factor (GM-CSF), and generally populate the tumor microenvironments. Yet, the role of MCs in cancer pathologies remains controversial with evidence for both anti-tumor and pro-tumor effects. Here, we review the studies examining the role of MCs in multiple forms of cancer, provide an alternative, MC-based hypothesis underlying the mechanism of therapeutic tumor IgE efficacy in clinical trials, and propose a novel strategy for using tumor-targeted, IgE-sensitized MCs as a platform for developing new cellular cancer immunotherapies. This autologous MC cancer immunotherapy could have several advantages over current cell-based cancer immunotherapies and provide new mechanistic strategies for cancer therapeutics alone or in combination with current approaches.

Tick bite induced α-gal syndrome highlights anticancer effect of allergy

Tick bite induced α-gal syndrome (AGS) following consumption of mammalian meat is a recently described intriguing disease occurring worldwide. Here we argue that AGS and delayed allergy in general is an adaptive defence method against cancer. Our hypothesis synthesizes two lines of supporting evidence. First, allergy has been shown to have direct anti-cancer effects with unknown mechanism. Second, eating processed meat was shown to be linked to developing cancer. Humans lost their genes encoding molecules α-gal 30 MYA and Neu5Gc 2 MYA, the latter co-occurring with the start of using fire. These molecules are acquired from external sources, as tick bite for α-gal and mammalian meat for Neu5Gc, the latter accumulating in tumors. The resulting specific delayed allergic response is a molecular adaptation to fight cancer. By further testing and applying our hypothesis, new avenues in cancer research and therapy will open that might save lives and decrease human suffering.

Clinical and immunological allergy assessment in cancer patients

Cancer is associated with immunodeficiency, while allergies result from immune system hyperactivity mediated by cytokines and immunoglobulins. The purpose of this study was to determine the relationship between immune environment of specific cancers and allergies, emphasizing cytokines related to Th1 and Th2 responses associated with IgE. 80 adults were distributed into two groups: control (n = 20) and cancer (n = 60), distributed in three subgroups (n = 20), head and neck, stomach, and prostate cancers. This study compared Th1 (IL-2) and Th2 (IL-4) parameters, anti-inflammatory, pro-inflammatory, or regulatory profile regarding both IgE levels and reported allergies, by means of clinical manifestations and IgE, IL-1β, IL-2, IL-4, IL-17, and TGF-β serum concentration. Clinically allergies were observed in 50% of the control group and in 20% of the cancer group (p = 0.009). IL-2 cytokine and TGF-β concentrations were higher in the patients with cancer as compared to the control (p < 0.005). However, there were IL-4, IL-17, and IL-1β decreases in the patients with cancer (p < 0.05). No correlation was observed between the cytokines studied and IgE and clinically proven allergies in both investigated groups. There was an inverse association between cancer and clinical allergy manifestations. In head and neck, stomach, and prostate cancers, an immunosuppressive serum tumor environment was predominant. There was no difference in cytokines related to Th1 and Th2 parameters in relation to IgE. No correlation was found between clinically proved allergies and immunity markers related to the same allergens.

Immunity and Breast Cancer: Focus on Eosinophils

The role of eosinophils, a cell type involved in the immune response to parasitic infections and allergies, has been investigated in different cancer types, in both tumor tissue and at the circulating level. Most studies showed a role mainly in conjunction with immunotherapy in melanomas and lung tumors, while few data are available in breast cancer. In this review, we summarize literature data on breast cancer, showing a prognostic role of circulating eosinophil counts as well as of the presence of tumor tissue infiltration by eosinophils. In particular, some studies showed an association between a higher circulating eosinophil count and a good prognosis, as well as an association with response to neoadjuvant chemotherapy in hormone receptor-negative/HER2-positive and in triple negative breast cancer. Several mechanistic studies have also been conducted in in vivo models, but the exact mechanism by which eosinophils act in the presence of breast cancer is still unknown. Further studies on this subject are desirable, in order to understand their role at the cellular level, identify related biomarkers and/or possibly search for new therapeutic targets.

Comorbidities in Atopic Dermatitis: An Update and Review of Controversies

Early onset of atopic dermatitis is considered a risk factor for any atopic disease, especially when the skin manifestations are persistent, and there is sensitization to multiple allergens and a family history. Atopic dermatitis is also thought to exert a synergistic effect with inflammation present in other organs and systems, as is the case in other immune-mediated inflammatory diseases. Most studies show a statistical relationship between obesity, various cardiometabolic comorbid conditions, and atopic dermatitis; this relationship is more marked when the disease is more severe or active over a longer period of time. However, other than epidemiological assessments, few studies provide in-depth evidence of functional mechanisms. Furthermore, various confounders, such as deterioration of quality of life and the psychological aspects of atopic dermatitis, could favor unhealthy habits, including a sedentary lifestyle and smoking, which could in turn increase the risk of morbidity and mortality. Chronic inflammation with differentiation toward a type 2 helper T cell pattern and the long-term use of immunosuppressants could be risk factors for some hematologic diseases, although they could exert a protective effect in others. The presence of proinflammatory cytokines capable of crossing the blood-brain barrier could favor an increase in the frequency of psychological diseases (eg, depression, anxiety, and suicidal ideation) and attention disorders (eg, attention deficit or hyperactivity). However, other factors, such as chronic pruritus and sleep disorders, could also play roles.