Mercury is an immunotoxic substance that has been shown to induce autoimmune disease in rodent models, characterized by lymphoproliferation, overproduction of immunoglobulin (IgG and IgE), and high circulating levels of autoantibodies directed at antigens located in the nucleus (anti-nuclear autoantibodies, or ANA) or the nucleolus (anti-nucleolar autoantibodies, or ANoA). We have reported elevated levels of ANA and ANoA in human populations exposed to mercury in artisanal gold mining, though other confounding variables that may also modulate ANA/ANoA levels were not well-controlled. The goal of this study is to specifically test whether occupational and environmental conditions (other than mercury exposure) that are associated with artisanal gold mining affect the prevalence of markers of autoimmune dysfunction. We measured ANA, ANoA, and cytokine concentrations in serum and compared results from mercury-exposed artisanal gold miners to those from diamond and emerald miners working under similar conditions and with similar socioeconomic status and risks of infectious disease. Mercury-exposed gold miners had higher prevalence of detectable ANA and ANoA and higher titers of ANA and ANoA as compared to diamond and emerald miners with no occupational mercury exposure. Also, mercury-exposed gold-miners with detectable ANA or ANoA in serum had significantly higher concentrations of pro-inflammatory cytokines IL-1β, TNF-α, and IFN-γ in serum as compared to the diamond and emerald miners. This study provides further evidence that mercury exposure may lead to autoimmune dysfunction and systemic inflammation in affected populations.

Background: Mercury is an immunotoxic metal that induces autoimmune disease in rodents. Highly susceptible mouse strains such as SJL/N, A.SW, B10.S (H-2 s ) develop multiple autoimmune manifestations after exposure to inorganic mercury, including lymphoproliferation, elevated levels of autoantibodies, overproduction of IgG and IgE, and circulating immune complexes in kidney and vasculature. A few studies have examined relationships between mercury exposures and adverse immunological reactions in humans, but there is little evidence of mercury-associated autoimmunity in humans.

The mechanisms of malarial anemia induction are poorly understood, but cytokines and autoantibodies are considered to play important roles. This work aimed at evaluating the degree of anemia and the plasmatic profile of the cytokines tumor necrosis factor alpha (TNF-␣), gamma interferon (IFN-␥), interleukin-12 (IL-12), migration inhibitory factor (MIF), and IL-10 and the monocyte chemotactic protein-1 (MCP-1) chemokine, as well as evaluating the presence of antibodies directed to components of the normal erythrocyte membrane and to cardiolipin in individuals with malaria from the Brazilian Amazon. No difference was observed in the frequency of anemia between patients infected by Plasmodium vivax and those infected by Plasmodium falciparum, and there was no relationship between the levels of parasitemia and the manifestations of anemia in P. vivax and P. falciparum patients. Significant increases in the concentrations of TNF-␣, IFN-␥, MIF, and MCP-1 were observed in patients with P. falciparum and P. vivax malaria, whereas the concentrations of IL-10 was increased only in patients with P. vivax infection. Higher concentrations of IL-12 and IL-10 were observed in the P. falciparum anemic patients, while for TNF-␣ this profile was observed in the nonanemic ones. P. vivax-infected and P. falciparum-infected patients with positive immunoglobulin M (IgM) or IgM and IgG responses, respectively, against blood-stage forms of the parasites had significantly lower hemoglobin levels than did those with negative responses. There was no correlation between the presence of anti-erythrocyte and anti-cardiolipin antibodies and the presence or intensity of the anemia. Our data suggest that in areas of low endemicity and unstable transmission of malaria, P. vivax and P. falciparum infections present similar characteristics in terms of the induction of anemia and cytokine responses.Severe malarial anemia and cerebral malaria are the main complications of Plasmodium falciparum infection. They are responsible for most of the estimated one to three million malaria-related deaths every year in the world, mainly among children below 5 years of age in sub-Saharan Africa (49). Severe malarial anemia is reported to be the earliest complication, usually affecting children below 2 years of age (57). Although severe anemia is a major concern in malaria pathology due to its high mortality rates, milder forms of anemia also are important, since this manifestation is responsible for considerable morbidity and is one of the major factors for the high disability-adjusted life years attributed to malaria (50,51,66). Iron deficiency, intestinal helminths, and human immunodeficiency virus infection make significant contributions to the pathogenesis of anemia in many African countries, but now there is substantial evidence suggesting that malaria is indeed a major underlying factor (28, 48).Although it has been estimated, the real impact of malarial anemia on the affected populations is unknown. The few available data mostly are restricted to studies ...

BackgroundIn human malaria, the naturally-acquired immune response can result in either the elimination of the parasite or a persistent response mediated by cytokines that leads to immunopathology. The cytokines are responsible for all the symptoms, pathological alterations and the outcome of the infection depends on the reciprocal regulation of the pro and anti-inflammatory cytokines. IL-10 and IFN-gamma are able to mediate this process and their production can be affected by single nucleotide polymorphisms (SNPs) on gene of these cytokines. In this study, the relationship between cytokine IL-10/IFN-gamma levels, parasitaemia, and their gene polymorphisms was examined and the participation of pro-inflammatory and regulatory balance during a natural immune response in Plasmodium vivax-infected individuals was observed.MethodsThe serum levels of the cytokines IL-4, IL-12, IFN-gamma and IL-10 from 132 patients were evaluated by indirect enzyme-linked immunosorbent assays (ELISA). The polymorphism at position +874 of the IFN-gamma gene was identified by allele-specific polymerase chain reaction (ASO-PCR) method, and the polymorphism at position -1082 of the IL-10 gene was analysed by PCR-RFLP (PCR-Restriction Fragment Length Polymorphism).ResultsThe levels of a pro- (IFN-gamma) and an anti-inflammatory cytokine (IL-10) were significantly higher in P. vivax-infected individuals as compared to healthy controls. The IFN-gamma levels in primoinfected patients were significantly higher than in patients who had suffered only one and more than one previous episode. The mutant alleles of both IFN-gamma and IL-10 genes were more frequent than the wild allele. In the case of the IFNG+874 polymorphism (IFN-gamma) the frequencies of the mutant (A) and wild (T) alleles were 70.13% and 29.87%, respectively. Similar frequencies were recorded in IL-10-1082, with the mutant (A) allele returning a frequency of 70.78%, and the wild (G) allele a frequency of 29.22%. The frequencies of the alleles associated with reduced production of both IFN-gamma and IL-10 were high, but this effect was only observed in the production of IFN-gamma.ConclusionsThis study has shown evidence of reciprocal regulation of the levels of IL-10 and IFN-gamma cytokines in P. vivax malaria, which is not altered by the presence of polymorphism in the IL-10 gene.

No abstract

Introduction:In Brazil, studies have shown that HTLV seroprevalence among pregnant women varies from 0 to 1.8%. However, this seroprevalence was unknown in the State of Pará, Brazil. The present study describes, for the first time, the HTLV seroprevalence among pregnant women from the State of Pará, Northern Brazil. Methods: 13,382 pregnant women were submitted to HTLV screening during prenatal care, and those with non-seronegative results to anti-HTLV were submitted to Western blot (WB) test to confirm and separate HTLV-1 and HTLV-2 carriers. Results: HTLV seroprevalence in the population of pregnant women was 0.3%, and HTLV-1 was identified in 95.3% of patients. The demographic profile of HTLV carriers was as follows: women with age between 20 and 40 years old (78.4%); residing in the metropolitan region of Belém, Pará (67.6%); and with educational level of high school (56.8%). Other variables related to infection were as follows: beginning of sexual intercourse between the age of 12 and 18 years old (64.9%) and have being breastfed for more than 6 months (51.4%). Most of the women studied had at least two previous pregnancies (35.1%) and no abortion (70.3%). Coinfections (syphilis and HIV) were found in 10.8% (4/37) of these pregnant women. Conclusions: Seroprevalence of HTLV infection in pregnant women assisted in basic health units from the State of Pará, Northern Brazil, was 0.3% similar to those described in other Brazilian studies. The variables related to infection were important indicators in identifying pregnant women with a higher tendency to HTLV seropositivity, being a strategy for disease control and prevention, avoiding vertical transmission.

Methylmercury (MeHg) is a ubiquitous environmental contaminant with known neurodevelopmental effects. In humans, prenatal exposures primarily occur through maternal consumption of contaminated fish. In this study, we evaluated the association between prenatal exposure to MeHg and titers of total immunoglobulins (Ig) and specific autoantibodies in both mothers and fetuses by analyzing maternal and cord blood serum samples. We examined multiple immunoglobulin isotypes to determine if these biomarkers could inform as to fetal or maternal responses since IgG but not IgM can cross the placenta. Finally, we evaluated serum cytokine levels to further characterize the immune response to mercury exposure. The study was conducted using a subset of serum samples (N=61 pairs) collected from individuals enrolled in a population surveillance of MeHg exposures in the Brazilian Amazon during 2000/2001. Serum titers of antinuclear and antinucleolar autoantibodies were measured by indirect immunofluorescence. Serum immunoglobulins were measured by enzyme-linked immunosorbent assay (ELISA) and BioPlex multiplex assay. Serum cytokines were measured by BioPlex multiplex assay. In this population, the geometric mean mercury level was within the 95th percentile for US populations of women of childbearing age but the upper level of the range was significantly higher. Fetal blood mercury levels were higher (1.35 times) than those in their mothers, but highly correlated (correlation coefficient [r]=0.71; 95% CI: 0.54, 0.89). Total IgG (r=0.40; 95% CI: 0.19, 0.62) and antinuclear autoantibody (odds ratio [OR]=1.05; 95% CI: 1.02, 1.08) levels in paired maternal and fetal samples were also associated; in contrast, other immunoglobulin (IgM, IgE, and IgA) levels were not associated between pairs. Total IgG levels were significantly correlated with both maternal (r=0.60; 95% CI: 0.25, 0.96) and cord blood mercury levels (r=0.61; 95% CI: 0.25, 0.97), but individual isotypes were not. Serum cytokines, interleukin-1β (r=0.37; 95% CI: 0.01, 0.73), interleukin-6 (r=0.34; 95% CI: 0.03, 0.65), and tumor necrosis factor-α (r=0.24; 95% CI: 0.015, 0.47), were positively correlated between maternal and fetal samples. Antinuclear and antinucleolar autoantibody titer and serum cytokine levels, in either maternal or cord blood, were not significantly associated with either maternal or cord blood mercury levels. These data provide further evidence that there are likely IgG biomarkers of mercury-induced immunotoxicity in this population since IgG levels were elevated with increased, and associated with, mercury exposure. However, unlike previous data from adult males and non-pregnant females, we found no evidence that antinuclear and antinucleolar autoantibody titer is a reliable biomarker of mercury immunotoxicity in this population.

No abstract