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Aflatoxin B 1 exposure and liver cirrhosis in Guatemala: a case–control study

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Objective In Guatemala, cirrhosis is among the 10 leading causes of death, and mortality rates have increased lately. The reasons for this heavy burden of disease are not clear as the prevalence of prominent risk factors, such as hepatitis B virus, hepatitis C virus and heavy alcohol consumption, appears to be low. Aflatoxin B 1 (AFB 1 ) exposure, however, appears to be high, and thus could be associated with the high burden of cirrhosis. Whether AFB 1 increases the risk of cirrhosis in the absence of viral infection, however, is not clear. Design Cirrhosis cases (n=100) from two major referral hospitals in Guatemala City were compared with controls (n=200) from a cross-sectional study. Logistic regression was used to estimate the ORs and 95% CIs of cirrhosis and quintiles of AFB 1 in crude and adjusted models. A sex-stratified analysis was also conducted. Results The median AFB 1 level was significantly higher among the cases (11.4 pg/mg) than controls (5.11 pg/mg). In logistic regression analyses, higher levels of AFB 1 was associated with cirrhosis (quintile 5 vs quintile 1, OR: 11.55; 95% CI 4.05 to 32.89). No attenuation was observed with adjustment by sex, ethnicity, hepatitis B virus status, and heavy alcohol consumption. A significantly increasing trend in association was observed in both models (p trend <0.01). Additionally, the cirrhosis–AFB 1 association was more prominent among men. Conclusions The current study found a significant positive association between AFB 1 exposure and cirrhosis. Mitigation of AFB 1 exposure and a better understanding of additional risk factors may be important to reduce the burden of cirrhosis in Guatemala.
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AlvarezCS, etal. BMJ Open Gastro 2020;7:e000380. doi:10.1136/bmjgast-2020-000380
Aatoxin B1 exposure and liver cirrhosis
in Guatemala: a case–control study
Christian S Alvarez ,1 Elisa Hernández,2 Kira Escobar,2 Carmen I Villagrán,2
María F Kroker- Lobos,3 Alvaro Rivera- Andrade,3 Joshua W Smith,4
Patricia A Egner,4 Mariana Lazo,5,6 Neal D Freedman,1 Eliseo Guallar,6
Michael Dean,1 Barry I Graubard,1 John D Groopman,4,6 Manuel Ramírez- Zea,3
Katherine A McGlynn1
To cite: AlvarezCS,
HernándezE, EscobarK, etal.
Aatoxin B1 exposure and liver
cirrhosis in Guatemala: a case–
control study. BMJ Open Gastro
2020;7:e000380. doi:10.1136/
bmjgast-2020-000380
Additional material is
published online only. To view
please visit the journal online
(http:// dx. doi. org/ 10. 1136/
bmjgast- 2020- 000380).
Received 13 January 2020
Revised 21 April 2020
Accepted 24 April 2020
For numbered afliations see
end of article.
Correspondence to
Dr Christian S Alvarez;
christian. alvarez@ nih. gov
Hepatology
Re- use permitted under CC BY.
Published by BMJ.
ABSTRACT
Objective In Guatemala, cirrhosis is among the 10
leading causes of death, and mortality rates have
increased lately. The reasons for this heavy burden of
disease are not clear as the prevalence of prominent risk
factors, such as hepatitis B virus, hepatitis C virus and
heavy alcohol consumption, appears to be low. Aatoxin
B1 (AFB1) exposure, however, appears to be high, and thus
could be associated with the high burden of cirrhosis.
Whether AFB1 increases the risk of cirrhosis in the
absence of viral infection, however, is not clear.
Design Cirrhosis cases (n=100) from two major referral
hospitals in Guatemala City were compared with controls
(n=200) from a cross- sectional study. Logistic regression
was used to estimate the ORs and 95% CIs of cirrhosis
and quintiles of AFB1 in crude and adjusted models. A sex-
stratied analysis was also conducted.
Results The median AFB1 level was signicantly higher
among the cases (11.4 pg/mg) than controls (5.11 pg/
mg). In logistic regression analyses, higher levels of AFB1
was associated with cirrhosis (quintile 5 vs quintile 1,
OR: 11.55; 95% CI 4.05 to 32.89). No attenuation was
observed with adjustment by sex, ethnicity, hepatitis
B virus status, and heavy alcohol consumption. A
signicantly increasing trend in association was observed
in both models (p trend <0.01). Additionally, the cirrhosis–
AFB1 association was more prominent among men.
Conclusions The current study found a signicant
positive association between AFB1 exposure and cirrhosis.
Mitigation of AFB1 exposure and a better understanding
of additional risk factors may be important to reduce the
burden of cirrhosis in Guatemala.
INTRODUCTION
Aflatoxin B1 (AFB1) is a known risk factor for
hepatocellular carcinoma (HCC),1 the domi-
nant type of liver cancer. In Guatemala, the
estimated incidence of HCC is the highest
in the Western hemisphere.2 The major risk
factors for HCC in Guatemala are not well
characterised, but the prevalence of AFB1
exposure appears to be high.3 The great
majority of HCCs (80%) develop in persons
with pre- existing cirrhosis.4 Therefore,
insights into the relationship between AFB1
and cirrhosis could be informative.
With over one million deaths per year,
cirrhosis is the 11th most common cause of
death worldwide.5 In combination with HCC,
cirrhosis accounts for 3.5% of all deaths glob-
ally.5 In Guatemala, cirrhosis is among the
10 leading causes of death and accounts for
an estimated 3.4% of all premature deaths.6
In addition, mortality rates of cirrhosis have
Summary box
What is already known about this subject?
Previous studies have reported an association be-
tween aatoxin B1 (AFB1) and cirrhosis, particularly
in populations with high prevalence of chronic infec-
tion with hepatitis B virus (HBV).
Whether AFB1 increases the risk of cirrhosis in the
absence of viral infection, however, has not been
well examined.
What are the new ndings?
In this case–control study, the median AFB1 lev-
el was signicantly higher among the cases than
controls.
Furthermore, there was a signicantly increasing
trend in the association between AFB1 and cirrho-
sis, even after adjustment with important covariates
such as sex, ethnicity, HBV status, and heavy alcohol
consumption.
In addition, the cirrhosis–AFB1 association was
stronger among men than women.
To our knowledge, this is the rst study to report
an association between AFB1 and cirrhosis in
Guatemala, a population with low prevalence of vi-
ral chronic hepatitis and low rate of heavy alcohol
consumption.
How might it impact on clinical practice in the
foreseeable future?
Interventions to reduce exposure to AFB1 as well as
effort to understand the role of other risk factors for
cirrhosis may be important to reduce the burden of
the disease in Guatemala.
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increased with an average annual per cent change of
14.4% over the past two decades,7 thus representing an
important public health issue in Guatemala.
Cirrhosis is a severe chronic liver disease which occurs
in response to liver injury, featuring encapsulation or
replacement of the damaged liver tissue by scar tissue
with distortion of the hepatic vasculature and architec-
ture.8 The disease is often asymptomatic until compli-
cations such as variceal bleeding, ascites and jaundice
occur.9 In the USA, Europe and some countries in Latin
America, cirrhosis is a leading indication for liver trans-
plantation.10 11 HCC and cirrhosis are known to share
common risk factors, including heavy alcohol consump-
tion, hepatitis B virus (HBV), hepatitis C virus (HCV),
and the related metabolic abnormalities of obesity and
non- alcoholic fatty liver disease (NAFLD).12 It has also
been reported that AFB1 is associated with cirrhosis
among persons infected with HBV or HCV.13–15 Whether
AFB1 increases the risk of cirrhosis in the absence of viral
infection, however, remains unclear.
In 2017, our group reported high levels of serum AFB1-
albumin adducts and low prevalences of HBV (0.9%) and
HCV (0.5%) infections in a cross- sectional study of Guate-
malan adults.3 In addition, our group has found that the
most important source of AFB1 exposure in the popula-
tion was consumption of tortillas, a primary staple in the
Guatemalan diet.16 This finding was consistent with prior
evidence of high AFB1 levels in maize samples across the
country.17 The current study was designed to assess the
association between AFB1 and cirrhosis in Guatemala.
METHODS
Study population
One hundred cirrhosis cases were ascertained between
February and November 2015 at two large public hospi-
tals in Guatemala City (Hospital General San Juan de
Dios and Hospital Roosevelt). The cases were outpa-
tients recruited at the hospitals’ outpatient clinics and
emergency rooms. Cirrhosis was diagnosed by abdom-
inal ultrasonography using a quantitative scoring system,
including morphological appearance of the liver surface,
liver parenchymal texture, intrahepatic vascular struc-
ture and spleen size.
Controls were selected from a cross- sectional study of
Guatemalan adults, aged 40 years and older, that was
conducted in 2016. The cross- sectional study enrolled
461 individuals from five departments of Guatemala in
order to determine the prevalence of risk factors for
liver cancer. The study recruitment was based on a non-
random household visit using maps of the community
when available. Details of the study have been previously
described.3 The selection of 200 controls for the current
study was based on the residence of the cirrhosis cases,
83% of whom resided in the department of Guatemala
or vicinity. Hence, 85% of the controls were chosen from
the departments of Guatemala and Escuintla (approxi-
mately 64 kilometers from the capital city). Individuals
in the cross- sectional study who reported a history of
cirrhosis were not eligible to be controls in the current
analysis (n=7). A flow chart of the inclusion and exclu-
sion criteria for cases and controls is presented in online
supplementary figure S1.
All cases and controls provided informed consent to
participate.
Data collection
Study participants were interviewed by trained staff using
a structured questionnaire that included information
on sociodemographic characteristics (eg, age, sex, resi-
dence, ethnicity and occupation), alcohol and maize
consumption, as well as use of medications. Study partic-
ipants also donated blood samples which were used to
determine hepatitis B surface antigen (HBsAg), antibody
to hepatitis C virus (anti- HCV) and AFB1- lysine (AFB1- lys)
adducts.
AFB1-lysine adduct assessments
The determination of AFB1- lys adduct levels was
performed by isotope- dilution mass spectrometry18
at Dr. John D Groopman’s laboratory at the Johns
Hopkins University Bloomberg School of Public Health.
Adduct concentrations (pg/AFB1- lys/mL serum) were
normalised to total serum albumin and expressed as pg
AFB1- lys adduct/mg albumin. Details of the laboratory
methods have been previously described.3
Study covariates
The covariates used in the analysis included age, sex,
ethnicity (indigenous vs not indigenous), residence
(department of Guatemala and vicinity vs other depart-
ments), occupation (farmer vs other), heavy alcohol
consumption (alcohol consumption 2 drinks for men
or 1 drink for women per day in the last year, or report
of a period in life where five or more drinks every day
were consumed), HBsAg and anti- HCV.
Statistical analysis
Medians and IQRs were calculated for continuous vari-
ables, and percentages were used for categorical vari-
ables. To examine differences in the characteristics
between cases and controls, t- tests or Wilcoxon rank- sum
tests were used for continuous variables, and χ2 or
exact tests were used for categorical variables. Addition-
ally, median and IQR of AFB1 for each covariate were
computed among the controls, and the differences in
the median were assessed by the Wilcoxon rank- sum
test. Unconditional logistic regression was used to calcu-
late the ORs and 95% CIs for the association between
cirrhosis and the serum AFB1- albumin adduct levels by
quintiles. A dose–response relationship between cirrhosis
and AFB1 was examined, and p trends were calculated by
scoring (1–5) the quintiles and including the score as a
continuous variable in unadjusted and adjusted models.
The logistic model selection was based on two different
approaches: a stepwise variable selection procedure and
examining the change in the estimated ORs by adding
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Open access
Table 1 Sociodemographic, clinical and other characteristics of individuals by cirrhosis status
Characteristics
Total
(N=300)
Cases
(n=100)
Controls
(n=200) P value*
Age, median (IQR) 55 (48–63) 54 (47–64) 56 (48–62) 0.07
Sex, n (%) 0.22
Male 129 (43.0) 48 (48.0) 81 (40.5)
Female 171 (57.0) 52 (52.0) 119 (59.5)
Indigenous ethnicity, n (%) 0.84
Yes 64 (21.3) 22 (22.0) 42 (21.0)
No 236 (78.7) 78 (78.0) 158 (79.0)
Department of residence, n (%) 0.57
Guatemala and vicinity 254 (84.7) 83 (83.0) 171 (85.5)
Other 46 (15.3) 17 (17.0) 29 (14.5)
Occupation, n (%) 0.06
Farmer 9 (3.0) 6 (6.0) 3 (1.5)
Others 291 (97.0) 94 (94.0) 197 (98.5)
Heavy alcohol consumption, n (%)† <0.01
Yes 59 (19.8) 51 (52.0) 8 (4.0)
No 239 (80.2) 47 (48.0) 192 (96.0)
HBsAg (seropositivity), n (%)† <0.01
Yes 8 (2.7) 7 (7.0) 1 (0.5)
No 290 (97.3) 93 (93.0) 197 (99.5)
Anti- HCV (seropositivity), n (%) 0.11
Yes 4 (1.3) 3 (3.0) 1 (0.5)
No 296 (98.7) 97 (97.0) 199 (99.5)
AFB1- albumin adduct levels, median (IQR) 7.3 (3.5–14.6) 11.4 (5.7–25.7) 5.11 (2.4–12.0) <0.01
*P values for categorical variables were obtained from χ2 test (sex, indigenous ethnicity, residence and heavy alcohol consumption) or exact
test (occupation, HBsAg and HCV status), and for the continuous variables Wilcoxon test (AFB1- lysine) or t- test (age).
†Categories do not sum to the total due to missing data.
AFB1, aatoxin B1; anti- HCV, antibody to hepatitis C virus; HBsAg, hepatitis B surface antigen; HCV, hepatitis C virus.
covariates, yielding the following covariates for the final
model: sex, ethnicity, HBV status, and heavy alcohol
consumption. Interaction terms were added to the final
model and significance was evaluated using the log rank
test. Finally, stratified analysis by sex was performed
because of a statistically significant interaction with sex.
All statistical analyses were conducted using SAS V.9.4
software, and two- sided p values <0.05 were regarded as
statistically significant without adjustment for multiple
comparisons.
RESULTS
Table 1 shows the characteristics of the study partici-
pants. The median age of the participants was 55 years
(IQR: 48–63). Of the participants, 57% were women.
The majority (85%) of individuals resided in the depart-
ments of Guatemala and vicinity. Cirrhosis cases were
more likely to report heavy alcohol consumption (52%)
than were the controls (4%) (p<0.01). The prevalence of
HBsAg was low (2.7%) but was statistically higher in cases
(7%) than controls (0.5%) (p<0.01). The prevalence of
anti- HCV was low (1.3%), and there was no significant
difference in prevalence between the cases (3%) and
controls (0.5%) (p=0.11). The median AFB1 level was
significantly higher among the cases (11.4 pg/mg) than
among the controls (5.11 pg/mg) (p<0.01).
Table 2 depicts the median values of AFB1- lys adducts by
sociodemographic and other characteristics among the
controls. Indigenous persons had a significantly higher
median AFB1- lys adduct levels than did non- indigenous
persons (15.2 pg/mg vs 4.8 pg/mg, p<0.01). Similarly,
individuals who resided outside the department of
Guatemala and vicinity had a significantly higher median
AFB1 -lys adduct level than did the individuals who lived
in the department of Guatemala and vicinity (17.8 pg/
mg vs 4.9 pg/mg, p<0.01). No differences in median
AFB1- lys adduct levels were observed by age, sex, occupa-
tion, excessive alcohol consumption, body mass index or
HBsAg and anti- HCV status.
Table 3 shows the results of the logistic regression anal-
ysis for the association between cirrhosis and AFB1- lys
adduct levels estimated as ORs. Higher levels of AFB1 -lys
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Table 2 Median and IQR of AFB1 by covariates in the
control group
Characteristics
AFB1- albumin
adduct levels*
(n=200) P value†
Age‡ 0.45
<56 years 4.7 (2.5–11.7)
≥56 years 5.5 (2.4–12.3)
Sex 0.24
Male 6.3 (2.7–12.6)
Female 4.7 (2.4–11.5)
Indigenous ethnicity <0.01
Yes 15.2 (4.3–36.0)
No 4.8 (2.3–9.5)
Department of residence <0.01
Guatemala and vicinity 4.9 (2.4–10.4)
Other 17.8 (3.4–33.4)
Occupation 0.95
Farmer 4.6 (1.5–33.4)
Other 5.2 (2.5–11.9)
Heavy alcohol consumption 0.20
Yes 4.0 (1.6–6.3)
No 5.1 (2.5–12.2)
Body mass index
<25.0 kg/m25.5 (3.2–9.5) 0.40
25.0–29.9 kg/m24.7 (2.3–11.3)
≥30 kg/m24.7 (2.3–8.8)
HBsAg (+) 0.53
Yes 9.5 (9.5–9.5)
No 5.1 (2.5–11.9)
Anti- HCV (+)
Yes 11.5 (11.5–11.5) 0.44
No 5.1 (2.4–12.1)
*Unit=pg AFB1- lysine/mg albumin.
†P values were obtained from Wilcoxon test.
‡The median age among controls is 56.
AFB1, aatoxin B1; anti- HCV, antibody to hepatitis C virus; HBsAg,
hepatitis B surface antigen.
was statistically significant associated with cirrhosis. In the
unadjusted analysis, the OR of quintile 5 versus quintile 1
of AFB1- lys adduct was 11.55 (95% CI 4.05 to 32.89), while
in the adjusted analysis the OR comparing the highest
quintile of AFB1- lys adduct with the lowest quintile was
12.41 (95% CI 3.23 to 47.74). In both models, there was
a significantly increasing trend in the relationship with
increasing quintile (p trend=0.001). Using a three- knot
restricted linear cubic regression spline, ORs were similar
to those of the quintile analysis (data not shown). In addi-
tion, adding interaction terms between AFB1- lys adducts
and the covariates in the final model yielded only one
statistically significant interaction, which was between
AFB1- lys adducts and sex (p=0.01).
The sex- specific analysis of the association between
cirrhosis and AFB1- lys adducts is presented in table 4. For
instance, among women, the adjusted OR comparing the
highest quintile of AFB1 with the lowest quintile was 5.61
(95% CI 1.24 to 25.38), while among men the equivalent
comparison had an adjusted OR of 9.64 (95% CI 1.21 to
76.94).
DISCUSSION
In the current study, cases had significantly higher levels
of AFB1- lys adducts than did the controls. In addition,
there was a statistically significantly increasing trend in
the association (OR) between AFB1- lys adduct levels and
cirrhosis that remained after adjustment for sex, ethnicity,
HBV status and heavy alcohol consumption. In addition,
evidence of effect modification by sex was observed, with
the association between AFB1- lys adduct levels and cirrhosis
being more pronounced among men than women.
The results of the current study are consistent with
other studies from Africa and Asia, where AFB1 exposure
has historically been high. In The Gambia, a study found
that probable exposure to AFB1 significantly increased
the risk of cirrhosis and that HBV infection had a syner-
gistic effect on the AFB1–cirrhosis association.19 Similarly,
a study in Egypt reported a significantly higher propor-
tion of AFB1 signature mutation in TP53 among persons
with chronic liver disease compared with controls.20 A
Turkish study also reported a significantly higher mean
level of AFB1 among individuals with cirrhosis compared
with controls .13 Similarly, a study in Taiwan found that
high serum AFB1 levels were associated with advanced
liver disease.14 In addition, a recent nested case–control
study in Taiwan reported a dose–response association
between AFB1- albumin adduct levels and cirrhosis.15
Fewer studies have been reported from the Amer-
icas, and the results have not been consistent. A study
in Mexico found that persons with cirrhosis had high
urinary levels of AFB1 adducts.21 In Brazil, an autopsy
study found an association between AFB1 residues and
chronic liver diseases, including cirrhosis.22 In contrast,
a US study reported that the AFB1 signature mutation
in TP53 was not evident in the tissue of individuals with
cirrhosis.23
In the current study, the AFB1 biomarker used reflects
the formation of mutagenic AFB1- DNA adducts, and the
risk of liver carcinogenesis has been demonstrated to
increase with the level of aflatoxin exposure.24 A mech-
anism underlying the possible development of cirrhosis
induced by AFB1 is not clear. In animal studies, paren-
chymal changes in the liver caused by steatosis, such as
liver cell damage, mononuclear cell infiltration and
fibrosis, have been observed after administration of
AFB1.25–31 Furthermore, a recent study has suggested that
myofibroblast- like cells may be involved in fibrosis due to
AFB1 exposure.31 Other studies have postulated similar
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Open access
Table 3 Association of cirrhosis status by quintile of AFB1- lysine adduct levels
AFB1- albumin adducts
Range
(pg/mg albumin) Cases Controls
Crude model Adjusted model*
OR 95% CI OR 95% CI
Quintile 1 0.49–2.68 5 54 1.00 – 1.00 –
Quintile 2 2.75–4.98 15 45 3.60 1.21 to 10.67 4.92 1.32 to 18.35
Quintile 3 5.07–9.58 21 39 5.82 2.02 to 16.76 4.85 1.31 to 17.88
Quintile 4 9.66–19.66 27 33 8.84 3.10 to 25.20 12.01 3.34 to 43.14
Quintile 5 19.68–171.58 31 29 11.55 4.05 to 32.89 12.41 3.23 to 47.74
P value for trend 0.001 0.001
Interaction terms were included for the covariates; only AFB1 and sex were statistically signicant (p=0.01).
*Adjusted for sex, ethnicity, HBV status, and heavy alcohol consumption.
AFB1, aatoxin B1; HBV, hepatitis B virus.
Table 4 Sex- specic association of cirrhosis status by quintile of AFB1- lysine adduct levels
AFB1- albumin adducts
Range
(pg/mg albumin) Cases Controls
Crude model Adjusted model*
OR 95% CI OR 95% CI
Female
Quintile 1 0.77–2.40 4 30 1.00 – 1.00 –
Quintile 2 2.42–4.36 9 25 2.70 0.74 to 9.82 2.31 0.52 to 10.27
Quintile 3 4.47–7.77 11 24 3.44 0.97 to 12.16 2.02 0.44 to 9.31
Quintile 4 7.83–13.97 12 22 4.09 1.16 to 14.39 3.95 0.96 to 16.35
Quintile 5 14.62–137.42 16 18 6.66 1.93 to 23.07 5.61 1.24 to 25.38
P value for trend 0.002 0.014
Male
Quintile 1 0.49–3.15 3 22 1.00 – 1.00 –
Quintile 2 3.42–6.59 4 22 1.33 0.27 to 6.67 2.85 0.36 to 22.41
Quintile 3 6.76–12.20 12 14 6.29 1.50 to 26.31 24.85 3.10 to 199.00
Quintile 4 12.49–29.60 16 10 11.73 2.77 to 49.62 25.44 3.26 to 198.64
Quintile 5 29.98–171.58 12 13 6.77 1.61 to 28.54 9.64 1.21 to 76.94
P value for trend <0.001 0.010
*Adjusted for ethnicity, HBV status, and heavy alcohol consumption.
AFB1, aatoxin B1; HBV, hepatitis B virus.
mechanisms, including formation of DNA adducts,
protein adducts, and lipid peroxidation.32 In addition, it
has been suggested that AFB1 may act both as a procar-
cinogen to induce DNA damage and as a liver- damaging
agent.15 Liver injury has also been shown in experimental
animal studies to increase cytochrome p450 enzyme
activity, which increases the activation of AFB1 and results
in greater injury to the liver.33–35
Sex difference in the prevalence of cirrhosis has
been described in several studies. For example, a US
population- based survey reported that cirrhosis was
nearly seven times more common among men than
women.36 The study also reported that 54% of the cases
with cirrhosis were attributable to viral hepatitis, exces-
sive alcohol consumption and diabetes,36 all of which
have been reported to be more common in men than
in women.37–39 In general, the prevalence and severity of
NAFLD also appear to be higher in men compared with
women.40 Sex differences in AFB1 levels and in the metab-
olism of AFB1 have also been observed in some studies.
Our previous work in Guatemala found that men had
significantly higher circulating levels of AFB1- lys adducts
than women.3 Animal studies have shown that castration
of male rats reduced the hepatic metabolism of AFB1
(approximately 50%),41 and have reported that male rats
are more likely to develop AFB- induced glutathione- S-
transferase- P- positive hepatocytes (a marker of preneo-
plastic foci) than do female rats.42 This evidence may
help to explain the current finding of the AFB1–cirrhosis
association being more pronounced among men than
women.
To our knowledge, this is the first study to assess the asso-
ciation between AFB1 and cirrhosis in Guatemala, a popula-
tion with low prevalence of viral chronic hepatitis and a low
rate of heavy alcohol consumption. The strengths of the
current study include the use of a robust biomarker of AFB1
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Open access
exposure and the use of a community- based control group
that is representative of the underlying general population.
In addition, the diagnoses of cirrhosis were determined by
ultrasound. Although ultrasound is not the gold standard
for diagnosing cirrhosis, it has been reported that the diag-
nostic accuracy of ultrasound in the detection of cirrhosis
is clinically acceptable,43 with a sensitivity of 52%–69% and
a specificity of 74%–89%.44
Limitations of the current study include that the
AFB1- lys biomarker levels were determined at a single
point in time, which may not accurately reflect the
cumulative AFB1 exposure over time. However, as maize
is the most important staple in the Guatemalan diet,
it is unlikely that dietary exposure varied greatly over
time. In addition, lack of information on other factors
among the cases, such as body size and clinical param-
eters, precluded the ability to examine their effects on
the AFB1–cirrhosis relationship. As there was no signifi-
cant relationship between body size and AFB1 among the
controls, however, it is unlikely that body size would have
an effect on the AFB1–cirrhosis relationship.
In conclusion, the current study found that cirrhosis
was associated with AFB1 in Guatemala, a country with
a high burden of liver disease. Interventions to mitigate
exposure to AFB1 as well as efforts to understand the role
of other risk factors for cirrhosis may be important to
reduce the burden of the disease in Guatemala.
Author afliations
1Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville,
Maryland, USA
2Centro de Investigaciones Biomédicas, Facultad de Ciencias Médicas, Universidad
de San Carlos de Guatemala, Guatemala, Guatemala
3INCAP Research Center for the Prevention of Chronic Diseases, Institute of
Nutrition of Central America and Panama, Guatemala, Guatemala
4Department of Environmental Health and Engineering, Bloomberg School of Public
Health, Johns Hopkins University, Baltimore, Maryland, USA
5Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore,
Maryland, USA
6Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins
University, Baltimore, Maryland, USA
Contributors Conceptualisation: EH, KE, CIV, CSA, KAM. Methodology: BIG, CSA,
KAM. Formal analysis: CSA. Writing the original draft: CSA, KAM. Review and
editing: ARA, MFKL, JWS, PE, ML, NF, EG, MD, JDG, MRZ.
Funding The study was funded by Dirección General de Investigación (DIGI),
San Carlos University of Guatemala; the US National Institutes of Health (grants
P30CA006973- 52S3 and T32ES007141); and the Intramural Research Program of
the National Cancer Institute, US National Institutes of Health.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval The cirrhosis study was approved by the institutional review
boards of both public hospitals, and the cross- sectional study was approved by the
institutional review boards of Johns Hopkins University Bloomberg School of Public
Health and the Institute of Nutrition of Central America and Panama (INCAP).
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data that support the ndings of this study are
available upon request from the authors.
Open access This is an open access article distributed in accordance with the
Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits
others to copy, redistribute, remix, transform and build upon this work for any
purpose, provided the original work is properly cited, a link to the licence is given,
and indication of whether changes were made. See: https:// creativecommons. org/
licenses/ by/ 4. 0/.
ORCID iD
Christian SAlvarez http:// orcid. org/ 0000- 0002- 5338- 0444
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... 6 In this regard, dietary exposure to aflatoxin B 1 (AFB 1 ), a fungal toxin produced by Aspergillus flavus and Aspergillus parasiticus, has been implicated as a potential etiologic factor for liver cirrhosis in numerous epidemiological studies. [7][8][9][10] For instance, a recent study done in Guatemala, where maize is the primary staple cereal, known to be contaminated with AFB 1 , found a significant association between AFB 1 exposure and liver cirrhosis. 9 In Eastern Ethiopia, several studies have shown severe contamination of principal dietary staple foods and cash crops including, sorghum, maize, and ground nut with AFB 1 . ...
... [7][8][9][10] For instance, a recent study done in Guatemala, where maize is the primary staple cereal, known to be contaminated with AFB 1 , found a significant association between AFB 1 exposure and liver cirrhosis. 9 In Eastern Ethiopia, several studies have shown severe contamination of principal dietary staple foods and cash crops including, sorghum, maize, and ground nut with AFB 1 . [11][12][13][14][15] Despite these studies, there has been little direct evidence linking AFB 1 exposure to the etiology of liver cirrhosis. ...
... 8 Our study demonstrated that the median AF-alb level was significantly higher among cases (11.0 pg/mg) than controls (7.0 pg/ mg), and patients exposed to high levels of AF-alb adduct were also at significantly higher risk of developing liver cirrhosis. The results of the present study are consistent with other studies reported from Africa, 7 Asia, 9 and South America, 9 where there is a high burden of aflatoxin exposure. The Gambian study also showed a synergy between AFB 1 exposure and HBV infection on the risk of liver cirrhosis. ...
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Background Liver cirrhosis is a global health problem due to a large number of disability-associated life years and mortality. However, evidence is scarce on its causes in Eastern-Ethiopia, a place where there is a high prevalence of liver cirrhosis of unknown etiology. This study attempted to identify the risk factors related to liver cirrhosis in the area. Methods A case-control study was conducted at a tertiary care hospital from January 2020 to July 2021. Following diagnoses using an ultrasound-based cirrhosis scale, a total of 127 cases were identified and compared with 253 control patients. A structured questionnaire and data abstraction form were used to collect demographic, lifestyle, and clinical information. A blood sample was also taken from each participant for clinical chemistry, hepatitis B virus (HBV), and hepatitis C virus tests as well as for an aflatoxin B1 (AFB1) albumin adduct (AF-alb) assay. Binary logistic regression analysis was used to determine predictors of liver cirrhosis. Results AF-alb levels were detected in 75% of the cases and 64% of the controls, with a median (IQR) level of 11 pg/mg (5.5–25) and 7.0 pg/mg (4.3–20.5), respectively (p<0.05). Moreover, the number of subjects with high AF-alb levels (≥8.6 pg/mg) was greater in cases (45%, p<0.05)) than controls (28%). Age ≥55 years (adjusted odds ratio (AOR)=0.4; 95% CI: 0.2, 0.8), being a farmer (AOR= 3.0; 95% CI: 1.5, 6.0), family history of liver disease (AOR= 2.9; 95% CI: 1.1, 7.9), HBV seropositivity (AOR=4.0; 95% CI: 1.9, 8.8), and exposure to high levels of AF-alb (AOR=2.0; 95% CI: 1.1, 3.7) were significantly associated with liver cirrhosis. Conclusion This study found a strong link between AFB1 exposure and liver cirrhosis. Mitigation of aflatoxin exposure and a better understanding of additional environmental risk factors like pesticides may be necessary to reduce the disease burden in Ethiopia.
... These fungal-produced secondary compounds are responsible for massive economic losses and they adversely affect global trade. Aflatoxins are considered the most toxic group of mycotoxins as they are known carcinogenic compounds, being linked to liver cancer [3][4], implicated in the stunting of children's growth [5] and sometimes cause acute death [6]. Aflatoxin-producing Aspergillus species can infect many crops but have an affinity for cereals and nuts. ...
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Background: Aflatoxin is one of the most problematic fungal-produced toxins as it is responsible for massive global agricultural losses and is deleterious to both human and animal health. Contamination of crops by certain strains of Aspergillus fungi accumulate aflatoxin in both post- and pre-harvest conditions. Methods: In this report, we tested the aflatoxin-degradation efficiency of an endogenously expressed enzyme in harvested maize kernels. In post-harvest conditions, equivalent loads of A. flavus were used to infect harvested maize kernels previously engineered to express an aflatoxin-degrading enzyme from the Honey mushroom fungus. Results: No measurable, or significantly reduced, levels of aflatoxin were detected in all the enzyme-expressing harvested kernels initially and then 3 days post –harvest the transgenic kernels amassed aflatoxin. Conclusions: This is the first report of an enzyme degradation of aflatoxin in a crop in harvested kernels. This demonstrates the potential of this strategy to aid in the mitigation of aflatoxin in post-harvest conditions.
... One survey in Guatemala noted that 22% of maize samples contained over 20 ppb, the threshold for general consumption in the U.S, and 14% contained over 10 times the threshold (200 ppb) [6]. The people of Guatemala have unhealthy biomarkers consistent with chronic aflatoxin exposure and associated with cirrhosis, liver cancer and childhood stunting [6][7][8][9]. ...
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Aflatoxin contamination of maize is a leading threat to health in Guatemala. This contamination is the result of infection from Aspergillus flavus and has been effectively reduced in other countries through application of nonaflatoxigenic, indigenous strains of A. flavus. We collected 82 maize samples from throughout Guatemala in two years and isolated 272 A. flavus from these samples, including 126 unique genotypes. We provide here a phenotypic and simple sequence repeat (SSR)-based genotypic description of these isolates, as well as an analysis of the diversity of this population. High levels of genetic diversity were observed with the nonaflatoxigenic isolates in this study, but this information contributes to the development of indigenous aflatoxin biocontrol products.
... 29 This finding has been corroborated by another study from Guatemala. 30 Also, a recent meta-analysis by Mekuria et al. showed that there is a significant increase in the risk of liver cirrhosis in individuals with significant aflatoxin exposure. 31 Several other studies have demonstrated a synergistic role between aflatoxin exposure and chronic hepatitis B virus (CHBV)infection in the pathogenesis of HCC, and furthermore, evidence is beginning to be available to demonstrate that this synergy may be via a cirrhotic pathway. ...
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Background Aflatoxin B1causes damage to the DNA by the alkylation of bases and P53 mutation. Exposure to this mycotoxin is associated with the development of liver cancer. Measures to reduce grain and cereal contamination have been a focus however, the effects of these measures are still lagging behind and exposure continues to occur even in populations at risk of developing liver cancer. Objective To quantify aflatoxin B1 exposure in a population of HIV infected patients with and without HCC. Method This was a cross-sectional study among 196 patients with HIV and or HCC. We evaluated the exposure to aflatoxin B1 using the Aflatoxin M1 metabolite by ELISA on urine samples. Results A total of 196 participants consisting of 163 (83.2%) HIV positive and 28 (14.3%) HCC. Mean age is 46.64±10.8 years. The median aflatoxin (IQR) aflatoxin M1level is 177.3(112.5-272) pg/ml. Only 8(4.1%) of the participant had no exposure to aflatoxin B1. The median (IQR) aflatoxin for fibrosis score ≥ 13kpa (178.7(112.9-286.8) pg/ml) VS < 13kpa (173.5(107.9-250.4)), p = 0.046. Conclusion There is high prevalence of aflatoxin B1 exposure in this population. Concerted efforts must be put in place to mitigate exposure because of the potential effects of short- and long-term exposure to aflatoxin.
... Thus, after the measurement of the total HSA concentration using one of the several available analytical approaches, AFB 1 -lys adduct values were normalized for assay input through their expression relative to the total HSA in the sample. These analytical methods are no longer the state-of-the-art approach for the measurement of AFB 1 -lys adducts, but the practice of normalization to HSA measured in a separate aliquot of serum (or plasma) has remained as a convention, including in previous reports from our group [8][9][10][11][12][13][14]. ...
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Aflatoxin B1 (AFB1) is a known human hepatocarcinogen and a recent study reported elevated AFB1 levels, measured by serum albumin biomarkers, among Guatemalan adults. While AFB1 can contaminate a variety of foodstuffs, including maize, Guatemala's main dietary staple, the relationship of maize intake to serum AFB1-albumin adducts levels in Guatemala has not been previously examined. As a result, a cross-sectional study was conducted among 461 Guatemalan adults living in five geographically distinct departments of the country. Participants provided a serum sample and completed a semi-quantitative food frequency questionnaire and a sociodemographic questionnaire. Multiple linear regression analysis was used to estimate the least square means (LSQ) and 95% confidence intervals (95% CI) of log-transformed AFB1-albumin adducts by quintiles of maize consumption in crude and adjusted models. Additionally, analyses of tortilla consumption and levels of maize processing were conducted. The median maize intake was 344.3 g per day [Interquartile Range (IQR): 252.2, 500.8], and the median serum AFB1-albumin adduct level was 8.4 pg/mg albumin (IQR: 3.8, 22.3). In adjusted analyses, there was no association between overall maize consumption and serum AFB1-albumin levels. However, there was a statistically significant association between tortilla consumption and AFB1-albumin levels (ptrend = 0.01). The LSM of AFB1-albumin was higher in the highest quintile of tortilla consumption compared to the lowest quintile [LSM:9.03 95%CI: 7.03,11.70 vs 6.23, 95%CI: 4.95,8.17, respectively]. These findings indicate that tortilla may be an important source of AFB1 exposure in the Guatemalan population. Therefore, efforts to control or mitigate AFB1 levels in contaminated maize used for tortillas may reduce overall exposure in this population.
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Liver disease accounts for approximately 2 million deaths per year worldwide, one million due to complications of cirrhosis and one million due to viral hepatitis and hepatocellular carcinoma. Cirrhosis is currently the 11th most common cause of death globally and liver cancer is the 16th leading cause of death; combined, they account for 3.5% of all deaths worldwide. Cirrhosis is within the top 20 causes of disability-adjusted life years and years of life lost and account for 1.6% and 2.1% of worldwide burden. About 2 billion people consume alcohol worldwide and upwards of 75 million are diagnosed with alcohol use disorders and are at risk for alcohol associated liver disease. Approximately 2 billion adults are obese or overweight and over 400 million have diabetes; both serve as risk factors for the increase in non-alcoholic fatty liver disease as well as hepatocellular carcinoma. The global prevalence of hepatitis B (3.5%) and hepatitis C (1%) is high. Drug induced liver injury continues to increase as a major cause of acute hepatitis. Liver transplantation is the second most common solid organ transplantation after kidney transplantation worldwide. However, less than 10% of global needs of organ transplantation are met at current rates of transplantation. Though these numbers are sobering, they offer an important opportunity to improve public health given that most causes of liver diseases are preventable.
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We aimed to determine whether aflatoxin dietary exposure plays a role in the high incidence of hepatocellular carcinoma (HCC) observed among Hispanics in South Texas. We measured TP53R249S somatic mutation, hallmark of aflatoxin etiology in HCC, using droplet digital PCR and RFLP. TP53R249S mutation was detected in 3 of 41 HCC tumors from Hispanics in South Texas (7.3%). We also measured TP53R249S mutation in plasma cell-free DNA (cfDNA) from 218 HCC patients and 96 Hispanic subjects with advanced fibrosis or cirrhosis, from South Texas. The mutation was detected only in Hispanic and Asian HCC patients, and patients harboring TP53R249S mutation were significantly younger and had a shorter overall survival. The mutation was not detected in any Hispanic subject with advanced fibrosis or cirrhosis. Genes involved in cell-cycle control of chromosomal replication and in BRCA1-dependent DNA damage response were enriched in HCCs with TP53R249S mutation. The E2F1 family members, E2F1 and E2F4, were identified as upstream regulators. TP53R249S mutation was detected in 5.7% to 7.3% of Hispanics with HCC in South Texas. This mutation was associated with a younger age and worse prognosis. TP53R249S was however not detected in Hispanics in South Texas with cirrhosis or advanced fibrosis. Aflatoxin exposure may contribute to a small number of HCCs in Hispanics in South Texas, but the detection of TP53R249S mutation in plasma cfDNA is not a promising biomarker of risk assessment for HCC in subjects with cirrhosis or advanced fibrosis in this population. Cancer Prev Res; 1-9. ©2017 AACR.