Evidence from a large-scale meta-analysis indicates eczema reduces the incidence of glioma

AllergoOncology: Biomarkers and refined classification for research in the allergy and glioma nexus-A joint EAACI-EANO position paper

Epidemiological studies have explored the relationship between allergic diseases and cancer risk or prognosis in AllergoOncology. Some studies suggest an inverse association, but uncertainties remain, including in IgE-mediated diseases and glioma. Allergic disease stems from a Th2-biased immune response to allergens in predisposed atopic individuals. Allergic disorders vary in phenotype, genotype and endotype, affecting their pathophysiology. Beyond clinical manifestation and commonly used clinical markers, there is ongoing research to identify novel biomarkers for allergy diagnosis, monitoring, severity assessment and treatment. Gliomas, the most common and diverse brain tumours, have in parallel undergone changes in classification over time, with specific molecular biomarkers defining glioma subtypes. Gliomas exhibit a complex tumour-immune interphase and distinct immune microenvironment features. Immunotherapy and targeted therapy hold promise for primary brain tumour treatment, but require more specific and effective approaches. Animal studies indicate allergic airway inflammation may delay glioma progression. This collaborative European Academy of Allergy and Clinical Immunology (EAACI) and European Association of Neuro-Oncology (EANO) Position Paper summarizes recent advances and emerging biomarkers for refined allergy and adult-type diffuse glioma classification to inform future epidemiological and clinical studies. Future research is needed to enhance our understanding of immune-glioma interactions to ultimately improve patient prognosis and survival.

Asthma reduces glioma formation by T cell decorin-mediated inhibition of microglia

To elucidate the mechanisms underlying the reduced incidence of brain tumors in children with Neurofibromatosis type 1 (NF1) and asthma, we leverage Nf1 optic pathway glioma (Nf1^OPG) mice, human and mouse RNAseq data, and two different experimental asthma models. Following ovalbumin or house dust mite asthma induction at 4-6 weeks of age (WOA), Nf1^OPG mouse optic nerve volumes and proliferation are decreased at 12 and 24 WOA, indicating no tumor development. This inhibition is accompanied by reduced expression of the microglia-produced optic glioma mitogen, Ccl5. Human and murine T cell transcriptome analyses reveal that inhibition of microglia Ccl5 production results from increased T cell expression of decorin, which blocks Ccl4-mediated microglia Ccl5 expression through reduced microglia NFκB signaling. Decorin or NFκB inhibitor treatment of Nf1^OPG mice at 4-6 WOA inhibits tumor formation at 12 WOA, thus establishing a potential mechanistic etiology for the attenuated glioma incidence observed in children with asthma.

Components of particulate matter air-pollution and brain tumors

BACKGROUND

Air pollution is an established carcinogen. Evidence for an association with brain tumors is, however, inconclusive. We investigated if individual particulate matter constituents were associated with brain tumor risk.

METHODS

From comprehensive national registers, we identified all (n = 12 928) brain tumor cases, diagnosed in Denmark in the period 1989-2014, and selected 22 961 controls, matched on age, sex and year of birth. We established address histories and estimated 10-year mean residential outdoor concentrations of particulate matter < 2.5 µm, primarily emitted black carbon (BC) and organic carbon (OC), and combined carbon (OC/BC), as well as secondary inorganic and organic PM air pollutants from a detailed dispersion model. We used conditional logistic regression to calculate odds ratios (OR) per inter quartile range (IQR) exposure. We adjusted for income, marital and employment status as well as area-level socio-demographic characteristics.

RESULTS

Total tumors of the brain were associated with OC/BC (OR: 1.053, 95%CI: 1.005-1.103, per IQR). The data suggested strongest associations for malignant tumors with ORs per IQR for OC/BC, BC and OC of 1.063 (95% CI: 1.007-1.123), 1.036 (95% CI: 1.006-1.067) and 1.030 (95%CI: 0.979-1.085), respectively. The results did not indicate adverse effects of other PM components.

CONCLUSIONS

This large, population based study showed associations between primary emitted carbonaceous particles and risk for malignant brain tumors. As the first of its kind, this study needs replication.

Intracranial tumors of the central nervous system and air pollution - a nationwide case-control study from Denmark

BACKGROUND

Inconclusive evidence has suggested a possible link between air pollution and central nervous system (CNS) tumors. We investigated a range of air pollutants in relation to types of CNS tumors.

METHODS

We identified all (n = 21,057) intracranial tumors in brain, meninges and cranial nerves diagnosed in Denmark between 1989 and 2014 and matched controls on age, sex and year of birth. We established personal 10-year mean residential outdoor exposure to particulate matter < 2.5 μm (PM_2.5), nitrous oxides (NO_X), primary emitted black carbon (BC) and ozone. We used conditional logistic regression to calculate odds ratios (OR) linearly (per interquartile range (IQR)) and categorically. We accounted for personal income, employment, marital status, use of medication as well as socio-demographic conditions at area level.

RESULTS

Malignant tumors of the intracranial CNS was associated with BC (OR: 1.034, 95%CI: 1.005-1.065 per IQR. For NO_x the OR per IQR was 1.026 (95%CI: 0.998-1.056). For malignant non-glioma tumors of the brain we found associations with PM_2.5 (OR: 1.267, 95%CI: 1.053-1.524 per IQR), BC (OR: 1.049, 95%CI: 0.996-1.106) and NO_x (OR: 1.051, 95% CI: 0.996-1.110).

CONCLUSION

Our results suggest that air pollution is associated with malignant intracranial CNS tumors and malignant non-glioma of the brain. However, additional studies are needed.

Participation of tumor suppressors long non-coding RNA MEG3, microRNA-377 and PTEN in glioma cell invasion and migration

PURPOSE

Glioma is a common and fatal intracranial tumor. Both miR-377 and lncRNA MEG3 are tumor suppressors. This study was performed to investigate the association between miR-377 and lncRNA MEG3 in glioma cells.

METHODS

U118 and U251 cell lines were incubated in Dulbecco's modified Eagle's medium supplemented with miR-377 mimics, MEG3 siRNA (si-MEG3) and/or MEG3 overexpression plasmids (pc-MEG3) for 48 h. Cell migration, invasion, apoptosis, cell cycle distribution and the expression of E26 tansformation-specific-1 (ETS-1), phosphatase and tensin homologue (PTEN), E-cadherin, N-cadherin and β-catenin were detected.

RESULTS

MiR-377 mimics increased MEG3 expression and decreased the number of migrated and invaded U118 and U251 cells, without influence on apoptosis in both cell lines. Si-MEG3 transfection increased U118 cell migration and invasion and rescued miR-377 mimics-induced inhibitory in cell migration and invasion. Si-MEG3 decreased U118 cell apoptosis and induced G0/G1 cell cycle arrest, and pc-MEG3 increased U251 cell apoptosis via arresting cell cycle at G2/M phage. MiR-377 mimics and si-MEG3 increased the relative expression level of N-cadherin mRNA, and both si-MEG3 and pc-MEG3 increased E-cadherin in glioma cells. MiR-377 mimics increased ETS-1 mRNA in U118 cells, but decreased it in U251 cells. PTEN was increased by miR-377 mimics and si-MEG3 and decreased by pc-MEG3 in glioma cells.

CONCLUSIONS

These results suggested the link interaction of MEG3 with miR-377 and PTEN, but not functioning as the competing endogenous RNA. MiR-377 mimics and MEG3 were tumor suppressors in glioma cells through regulating PTEN expression.

Use of Mendelian andomization for dentifying isk actors for rain umors

Gliomas are a group of primary brain tumors, the most common and aggressive subtype of which is glioblastoma. Glioblastoma has a median survival of just 15 months after diagnosis. Only previous exposure to ionizing radiation and particular inherited genetic syndromes are accepted risk factors for glioma; the vast majority of cases are thought to occur spontaneously. Previous observational studies have described associations between several risk factors and glioma, but studies are often conflicting and whether these associations reflect true casual relationships is unclear because observational studies may be susceptible to confounding, measurement error and reverse causation. Mendelian randomization (MR) is a form of instrumental variable analysis that can be used to provide supporting evidence for causal relationships between exposures (e.g., risk factors) and outcomes (e.g., disease onset). MR utilizes genetic variants, such as single nucleotide polymorphisms (SNPs), that are robustly associated with an exposure to determine whether there is a causal effect of the exposure on the outcome. MR is less susceptible to confounding, reverse causation and measurement errors as it is based on the random inheritance during conception of genetic variants that can be relatively accurately measured. In previous studies, MR has implicated a genetically predicted increase in telomere length with an increased risk of glioma, and found little evidence that obesity related factors, vitamin D or atopy are causal in glioma risk. In this review, we describe MR and its potential use to discover and validate novel risk factors, mechanistic factors, and therapeutic targets in glioma.

Allergic conditions and risk of glioma and meningioma in the CERENAT case-control study

Inverse association between allergic conditions and glioma risk has been consistently reported in epidemiological studies with little attention paid to potential environmental confounders; the association with meningioma risk is less consistent. We examined the association between allergy history and risk of glioma and meningioma in adults using data from the CERENAT (CEREbral tumors: a NATional study) multicenter case-control study carried out in 4 areas in France in 2004-2010. Participants' histories of doctor-diagnosed allergic asthma, eczema, rhinitis/hay fever and other allergic conditions were collected at onset through a detailed questionnaire delivered in a face-to-face interview. Conditional logistic regression for matched sets was adjusted for participants' educational level and mobile phone use. A total of 273 glioma cases, 218 meningioma cases and 982 matched controls selected from the local electoral rolls were analyzed. A significant inverse association was found between glioma and a history of any allergy (OR 0.52, 95% CI 0.36-0.75), with a dose-effect relationship with the number of allergic conditions reported (p-trend = 0.001) and a particularly strong association with hay fever/allergic rhinitis (OR 0.46, 95% CI 0.30-0.72). Interestingly, associations with glioma risk were more pronounced in women. For meningioma, no association was observed with overall or specific allergic conditions. Our findings confirmed the inverse association between allergic conditions and glioma risk but questioned the role of allergy in meningioma risk. Future research is needed to clarify the biological mechanism of overall allergy and allergic rhinitis on glioma and to confirm the different effect by gender.

Allergy is associated with reduced risk of glioma: A meta-analysis

BACKGROUND

Increasing evidences suggest that allergy may reduce the risk of glioma, so it is necessary to perform an up-to-data literature search and investigate this relationship by meta-analysis.

METHODS

We identified the included studies by searching PubMed and Web of Science and excluding irrelevant or ineligible articles. Nineteen studies from 15 articles, including 8435 cases and 118,719 controls, were selected for data extraction and synthesis.

RESULTS

Pooled outcomes showed that there was an inverse association between allergy and risk of glioma (OR=0.64, 95% CI=0.52-0.78, P<0.001). Meanwhile, asthma and eczema would reduce the risk of glioma by 33% and 23% (OR=0.67, 95% CI=0.59-0.75, P<0.001; OR=0.77, 95% CI=0.68-0.86, P<0.001), respectively. Sensitivity analyses confirmed the stability of these findings. Besides, no publication biases were detected regarding all the investigations.

CONCLUSIONS

Overall or specific allergy is protective against glioma. More prospective cohort studies or molecular laboratory experiments are warranted to elucidate the causation and key mechanism.

Expression of TAG1/APP signaling pathway in the proliferation and differentiation of glioma stem cells

The aim of the present study was to examine the role of the expression of transient axonal glycoprotein-1 (TAG1)/precursor protein (APP) signaling pathway in the proliferation and differentiation of glioma stem cells. A glioma cell line (U373) was used as well as fluorescence quantitative PCR, western blot analysis, and enzyme-linked immunosorbent assay (ELISA), to examine the role of the expression of TAG1/APP signaling pathway in the proliferation and differentiation of glioma stem cells after five generations of in vitro culture. The results showed that compared to the normal glioma cells, the expression of TAG1 and APP was significantly increased in the proliferation of glioma stem cells. The results of ELISA and western blot analysis also confirmed a significant elevation in the protein expression of TAG1 in glioma stem cells compared to normal human glioma cells. When glioma stem cells were cultured in differentiation medium, as revealed by RT-PCR, the expression of TAG1 and APP in glioma stem cells initially increased and then decreased. In addition, the protein expression of TAG1 and APP was consistent with the RT-PCR results. Compared with undifferentiated glioma stem cells, the expression of TAG1 and APP decreased gradually with the extension of differentiation time. In conclusion, the expression of TAG1/APP signaling pathway in glioma cells was abnormal. Thus, this pathway is involved in the proliferation and differentiation of glioma cells and promotes the proliferation of glioma cells to inhibit the differentiation of glioma cells.