Aflatoxin exposure in adults in southern and eastern Mexico in 2018: A descriptive study

OBJECTIVE

To estimate the frequency of detection and levels of aflatoxin B1-lysine adduct (AFB1-lys), an important hepatocellular carcinoma (HCC) risk factor, in eastern and southern Mexico.

MATERIALS AND METHODS

We determined serum AFB1-lys using mass spectrometry in a representative sample of 952 adults (weighted n = 7,493,354) from five states (Campeche, Chiapas, Tamaulipas, Veracruz and Yucatán) in 2018. We calculated overall and subgroup-specific frequency of detection and 95% confidence intervals (95%CI) and median AFB1-lys levels and quartiles.

RESULTS

The overall frequency of detection of AFB1-lys was 91.9% (95%CI 88.6, 94.3). The median AFB1-lys level was 0.172 pg/μL (Q1-Q3, 0.060-0.582). Levels differed geographically (median pg/μL, 0.361 for Veracruz and 0.061 for Yucatan) and were higher among men and older individuals. Levels were almost three times higher in rural relative to urban areas (0.317 vs. 0.123 pg/μL). We observed higher AFB1-lys exposure in lower socioeconomic status (SES) level populations.

CONCLUSION

AFB1-lys frequency of detection was very high and exposure levels were highest in Veracruz, men, rural areas, and among persons of lower SES. Understanding modifiable HCC risk factors in populations with unique epidemiological patterns could inform preventative interventions.

Abstract 4221: Aflatoxin exposure in a population-based representative sample of adults in Mexico in 2018

Importance: Southern Mexico and Guatemala, together represent the region with the highest liver cancer burden in the Americas. There is a higher burden of liver cancer in rural regions in eastern and southern Mexico and remarkably there is an equal number of cases in men and women. Reasons for this increased burden are not clear, but previous studies of food samples have found that contamination of maize with aflatoxin B1 (AFB1), a potent liver carcinogen, is common in the region while HBV and HCV seroprevalence is less than 0.5%. Few examinations of AFB1 levels in persons have been conducted.

Objective: To estimate the prevalence of exposure and circulating levels AFB1 in a representative sample of adults living in five regions across Mexico.

Study Design: We randomly selected a subsample of 955 adults ≥40 years who participated in Mexico’s National Health and Nutrition Survey 2018 (ENSANUT). These residents were from five states in eastern and southern Mexico and all provided a venous blood sample. We assessed AFB1 levels as pg AFB1-lys/µL in serum using mass spectrometry. The limits of detection and quantification were both 0.010 pg/μL.

Results: The mean age of participants was 56 years (± SD 11.7) and 54% were female. The overall prevalence of AFB1-lys detection was 92% (95% confidence intervals; 95%CI 88, 94%). The region with the lowest prevalence, 88% (95%CI 78, 94%), was Chiapas and the region with the highest prevalence was Veracruz 95% (95%CI 84, 98). Median AFB1 was 0.127 pg AFB1-lys/µL (interquartile range; IQR 0.054, 0.446) with a range from 0.066 (IQR, 0.033, 0.147) in Yucatán to 0.476 (IQR, 0.199, 1.355) in Veracruz. AFB1 exposure levels were higher in persons aged ≥60 years, men, and participants living in rural areas. We observed decreasing levels of AFB1 exposure with increasing socioeconomic status.

Conclusions: In a representative sample of adults in eastern and southern Mexico we observed a high prevalence of exposure to AFB1. For certain regions, AFB1 levels are comparable to those in Guatemala. These results suggest that AFB1 may be related to the increased burden of liver cancer in eastern and southern Mexico.

Citation Format: Adriana Monge, Katherine McGlynn, Luis Santiago-Ruiz, Jose Maria Remes-Troche, Karina Hernandez-Flores, Salvador Villapando-Hernandez, Martin Romero, John Groopman, Martin Lajous. Aflatoxin exposure in a population-based representative sample of adults in Mexico in 2018. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4221.

Aflatoxin levels and prevalence of TP53 aflatoxin-mutations in hepatocellular carcinomas in Mexico

Objective. To determine the exposure to aflatoxin B1 (AFB1) in southern Mexico and the presence of the aflatoxin signature mutation in hepatocellular carcinoma (HCC) tissue from patients from a cancer referral center. Materials and methods. We estimated the prevalence and distribution of AFB1 in a representative sample of 100 women and men from Chiapas using the National Health and Nutrition Survey 2018-19. We also examined the presence of the aflatoxin signature mutation in codon 249 (R249S), and other relevant mutations of the TP53 gene in HCC tissue blocks from 24 women and 26 men treated in a national cancer referral center. Results. The prevalence of AFB1 in serum samples was 85.5% (95%CI 72.1-93.1) and the median AFB1 was 0.117 pg/μL (IQR, 0.050–0.350). We detected TP53 R249S in three of the 50 HCCs (6.0%) and observed four other G>T transversions potentially induced by AFB1. Conclusion. Our analysis provides evidence that AFB1 may have a relevant role on HCC etiology in Mexico.

A major genetic determinant of autoimmune diseases is associated with the presence of autoantibodies in hypersensitivity pneumonitis

Background

Hypersensitivity pneumonitis is an immune-mediated disease triggered by exposure to organic particles in susceptible individuals. It has been reported that a subgroup of patients with hypersensitivity pneumonitis develops autoantibodies with or without clinical manifestations of autoimmune disease. However, the mechanisms involved in this process and the effect of the autoantibodies on clinical course in hypersensitivity pneumonitis is unknown. We evaluated the association between human leukocyte antigen (HLA) class II alleles and hypersensitivity pneumonitis patients with and without autoantibodies.

Methods

170 hypersensitivity pneumonitis patients were included. We analysed the presence of antinuclear antibodies, rheumatoid factor, anti-SSA/Ro, anti-SSB/La and anti-CCP at the time of diagnosis. In addition, in a subset of patients we evaluated anti-Scl-70, anti-neutrophil cytoplasmic antibody, and anti-DNA. HLA typing was performed using PCR sequence-specific primers in a high-resolution modality, including HLA-DRB1 and HLA-DQB1 loci. Statistical analysis was performed employing Epi-Info v7 and SPSS v20.

Results

60 hypersensitivity pneumonitis patients showed sera autoantibodies (HPAbs⁺), and 110 hypersensitivity pneumonitis patients did not (HPAbs⁻). The frequency of the allele HLA-DRB1*03:01 was remarkably increased in the HPAbs⁺ group (10.8% versus 0.45%; OR 30.14, 95% CI 3.83–237.1; p=1.65×10^-4 after Bonferroni's correction). Likewise, we found that the haplotype DRB1*03:01-DQB1*02:01, which is part of the 8.1 ancestral haplotype, a major genetic determinant of autoimmune diseases, confers significant risk to develop autoantibodies (OR 19.23, 95% CI 2.37–155.9; p=0.0088 after Bonferroni's correction). In addition, the HLA-DRB1*03:01 allele was associated with higher mortality in patients with hypersensitivity pneumonitis (adjusted OR 5.9, 95% CI 1.05–33.05; p=0.043).

Conclusions

A subset of hypersensitivity pneumonitis patients presents circulating autoantibodies and higher mortality that are associated with some alleles of 8.1 ancestral haplotype.

Alleles from 8.1 ancestral haplotype (#HLA-DRB1 and DQB1 loci) are associated with #autoantibodies production in #hypersensitivity #pneumonitis in a cohort of Mexican mestizo patientshttps://bit.ly/3bprPeB

MMP2 Polymorphism Affects Plasma Matrix Metalloproteinase (MMP)-2 Levels, and Correlates with the Decline in Lung Function in Hypersensitivity Pneumonitis Positive to Autoantibodies Patients

Among hypersensitivity pneumonitis (HP) patients have been identified who develop autoantibodies with and without clinical manifestations of autoimmune disease. Genetic factors involved in this process and the effect of these autoantibodies on the clinical phenotype are unknown. Matrix metalloproteinases (MMPs) have an important role in architecture and pulmonary remodeling. The aim of our study was to identify polymorphisms in the MMP1, MMP2, MMP9 and MMP12 genes associated with susceptibility to HP with the presence of autoantibodies (HPAbs+). Using the dominant model of genetic association, comparisons were made between three groups. For rs7125062 in MMP1 (CC vs. CT+TT), we found an association when comparing groups of patients with healthy controls: HPAbs+ vs. HC (p < 0.001, OR = 10.62, CI 95% = 4.34–25.96); HP vs. HC (p < 0.001, OR = 7.85, 95% CI 95% = 4.54–13.57). This rs11646643 in MMP2 shows a difference in the HPAbs+ group by the dominant genetic model GG vs. GA+AA, (p = 0.001, OR = 8.11, CI 95% = 1.83–35.84). In the linear regression analysis, rs11646643 was associated with a difference in basal forced vital capacity (FVC)/12 months (p = 0.013, β = 0.228, 95% CI95% = 1.97–16.72). We identified single-nucleotide polymorphisms (SNPs) associated with the risk of developing HP, and with the evolution towards the phenotype with the presence of autoantibodies. Also, to the decrease in plasma MMP-2 levels.