Teresa Binstock
Researcher in Developmental & Behavioral Neuroanatomy
June 30, 2009

In 2007, Ohshima and colleagues reported that levels of a plastics chemical known as bisphenol A (BPA) were inversely correlated with oral tolerance which - when suboptimal - is associated with food hypersensitivities and autoimmunity (1).

Background

Allergies to various foods are increasing in the U.S. and elsewhere (2). More than 60% among >2500 autism parents reported improvements when their autistic child is on a gluten-free or casein-free diet (3). Bisphenol A has become common in breast milk, cord blood, and bodies of humans (eg, 4-8) and may be etiologically significant in some and perhaps many cases of food hypersensitivity (1). As cited below, other BPA effects may be relevant to autism.

First, a technical but important aside: BPA was found to alter function of immune cells labeled with surface markers known as CD4 and CD25 (1). These cells participate in immunological anergy and, when functioning properly, minimize or prevent autoimmunity and induce appropriate oral tolerance to food antigens (1, 9-11).

Caveat and counter-caveat: The Ohshima et al findings occurred in a murine model wherein BPA levels were substantially higher than average levels found in humans (1). However, the findings may pertain to humans with impaired detoxification. For instance, glutathione participates in neutralization and detoxification of BPA (eg, 12-13). Many humans have one or more polymorphisms which diminish effectiveness or availability of glutathione (eg, 14-15). And weak alleles in GSH-related pathways are increasingly described in autism (eg, 16-17).  Furthermore, BPA detoxification includes glucuronidation, which can be affected by polymorphisms (eg, 18) and BPA-detoxification is affected by androgens (19-21). Lower levels of GSH, suboptimal utilization of GSH, weak alleles of genes participating in glucuronidation, and elevated androgens are factors suggesting relevance of BPA's role in food hypersensitivities among infants and children with impaired ability to detoxify BPA.

As prompted by the BPA oral-tolerance findings of Ohshima et al (1), a preliminary survey of peer-reviewed literature led to other parallels possibly relevant to BPA in children who become autistic or have one of the other autism-spectrum disorders.

1a. BPA levels are increased in the presence of androgens (19-21).
1b. Autism subgroups with polymorphisms in detox genes have been described (16-17).
1c. Research has identified autism subgroups with elevated androgens (22-23).

2a. BPA may affect natural killer (NK) cell function via BPA's effects upon CD4 CD25 T-regulatory (Treg cells) (24, 1).
2b. Researches have identified autism subgroups with low NK-cytotoxicity (25-26)

3a. BPA may alter expression of Toll-like receptors (TLRs) via BPA's effects upon CD4 CD25 Treg cells (27, 1).
3b. Atypical TLR reponses have been described in a subgroup of autism-spectrum children (28).

Conclusion

BPA may be relevant in various ways for subgroups of children with autism or other autism-spectrum disorders. Two pathways by which BPA is detoxified can be affected by genetic polymorphisms. That androgens modulate BPA levels suggests that boys are more likely to be affected, but clinical data are showing that, aside from autistic males, some females with autism have elevated androgens and thus may have atypically elevated levels of BPA. Furthermore, numerous pollutants - not just BPA - have found their way into human bodies and would contribute to utilization and possible depletion of nutrients needed for detoxification. In this complex context, BPA may contribute to food hypersensitivities in some children.

References

1: Transmaternal exposure to bisphenol a modulates the development of oral tolerance.
Ohshima Y et al. Pediatr Res. 2007 62(1):60-4.

Bisphenol A (BPA) is a representative endocrine disruptor that may have adverse effects on human health. Since the development of oral tolerance during infancy may play an important role in the prevention of food allergies, we examined whether transmaternal exposure to BPA influences the development of oral tolerance. To measure antigen-specific responses, female wild-type mice mated with male ovalbumin (OVA)-specific T-cell receptor transgenic (TCR-tg) mice were fed with BPA during pregnancy and while nursing. OVA was administered to OVA-TCR-tg offspring during their weaning period. Oral administration of both high and low doses of OVA suppressed OVA-specific cell proliferation and cytokine production in both BPA-exposed and nonexposed control mice, but the OVA-mediated suppression was significantly more diminished by the BPA exposure. The accumulation of CD4+CD25+Foxp3+ T cells was diminished in the BPA-exposed offspring. Moreover, after low dose OVA administration, serum OVA-specific IgG1 and IgG2a levels were higher in the BPA-exposed offspring than in nonexposed ones. Taken together, our results indicate that transmaternal exposure to BPA seems to modulate the mechanisms underlying tolerance induction; therefore, BPA may partially interrupt the development of oral tolerance.

2: Update on food allergy.
Sampson HA. J Allergy Clin Immunol. 2004 113(5):805-19.

3. Parent Ratings of Behavorial Effects of Biomedical Interventions
Autism Research Institute
http://www.autism.com/treatable/form34qr.htm

4. Parent bisphenol A accumulation in the human maternal-fetal-placental unit.
Schönfelder G et al. Environ Health Perspect. 2002 110(11):A703-7.
{free online} http://tinyurl.com/l34o5l

Bisphenol A (BPA), an endocrine disruptor, is employed in the manufacture of a wide range of consumer products. The suggestion that BPA, at amounts to which we are exposed, alters the reproductive organs of developing rodents has caused concern. At present, no information exists concerning the exposure of human pregnant women and their fetuses to BPA. We therefore investigated blood samples from mothers (n = 37) between weeks 32 and 41 of gestation. Afer the births, we also analyzed placental tissue and umbilical cord blood from the same subjects. We developed a novel chemical derivatization-gas chromatography/mass spectrometry method to analyze parent BPA at concentrations < 1 micro g/mL in plasma and tissues. Concentrations of BPA ranged from 0.3 to 18.9 ng/mL (median = 3.1 ng/mL) in maternal plasma, from 0.2 to 9.2 ng/mL (median = 2.3 ng/mL) in fetal plasma, and from 1.0 to 104.9 ng/g (median = 12.7 ng/g) in placental tissue. BPA blood concentrations were higher in male than in female fetuses. Here we demonstrate parent BPA in pregnant women and their fetuses. Exposure levels of parent BPA were found within a range typical of those used in recent animal studies and were shown to be toxic to reproductive organs of male and female offspring. We suggest that the range of BPA concentrations we measured may be related to sex differences in metabolization of parent BPA or variable maternal use of consumer products leaching BPA.

5. Determination of bisphenol A concentrations in human biological fluids reveals significant early prenatal exposure.
Ikezuki Y et al. Hum Reprod. 2002 17(11):2839-41.
{free online} http://humrep.oxfordjournals.org/cgi/content/full/17/11/2839

Background: There is broad human exposure to bisphenol A (BPA), an estrogenic endocrine-disrupting chemical widely used for the production of plastic products. BPA is reported to affect preimplantation embryos or fetuses and alter their postnatal development at doses typically found in the environment. We measured contamination of BPA in various kinds of human biological fluids by a novel enzyme-linked immunosorbent assay. METHODS: Blood samples were obtained from healthy premenopausal women, women with early and full-term pregnancy, and umbilical cord at full-term delivery. Ovarian follicular fluids obtained during IVF procedures and amniotic fluids obtained at mid-term and full-term pregnancy were also subject to BPA measurements. RESULTS: BPA was present in serum and follicular fluid at approximately 1-2 ng/ml, as well as in fetal serum and full-term amniotic fluid, confirming passage through the placenta. Surprisingly, an approximately 5-fold higher concentration, 8.3 +/- 8.7 ng/ml, was revealed in amniotic fluid at 15-18 weeks gestation, compared with other fluids. CONCLUSION: These results suggest accumulation of BPA in early fetuses and significant exposure during the prenatal period, which must be considered in evaluating the potential for human exposure to endocrine-disrupting chemicals.

6. Determination of bisphenol A in human breast milk by HPLC with column-switching and fluorescence detection.
Sun Y et al. Biomed Chromatogr. 2004 18(8):501-7.

A highly sensitive HPLC method was developed for the determination of xenoestrogenic compound, bisphenol A (BPA) in human breast milk samples. After a two-step liquid-liquid extraction, BPA was derivatized with fluorescent labeling reagent, 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride (DIB-Cl). The excess fluorescent reagent could be removed effectively using a column-switching system. The separation of DIB-BPA from endogenous materials in milk was carried out on two C(18) columns and fluorescence intensity was monitored at 475 nm with the excitation of 350 nm. A good linearity (r = 0.994) was observed of BPA in the concentration range of 0.2-5.0 ng mL(-1) in breast milk, and the detection limit was 0.11 ng mL(-1) at a signal-to-noise ratio of 3. Intra- and inter-day precision (RSD, %) were less than 8.7 and 10.4, respectively. Twenty-three breast milk samples of healthy lactating women were analyzed for the BPA concentration; the mean value was 0.61 +/- 0.20 ng mL(-1), with no correlation to the lipid content of milk samples.

7. Measurement of bisphenol A concentrations in human colostrum.
Kuruto-Niwa R et al. Chemosphere. 2007 Jan;66(6):1160-4.

Bisphenol A (BPA), an estrogenic endocrine disrupting chemical, has been reported to affect embryos and alter their postnatal development. In the present study, we measured the concentrations of BPA in human colostrum by a competitive enzyme-linked immunosorbent assay (ELISA) with the aim of understanding the present status of BPA burden in human breast milk in Shizuoka, Japan. Human colostral samples were collected from 101 healthy mothers within three days after delivery. The BPA concentrations of colostral samples were estimated by ELISA after the acetonitrile extraction and solid phase extraction column purification. BPA in 101 samples was detected in the concentration range of 1-7 ng ml(-1). The mean concentration of BPA was 3.41+/-0.13 (mean+/-SD) ng ml(-1). This is the first demonstration as to what BPA concentrations are in human colostrum. The BPA concentrations in colostrum were higher than those in blood sera samples obtained from healthy women in a previous study. In our study, there was no significant correlation between the concentrations of BPA in colostrum and the age and parity of mothers.

8.  Assessment of human contamination of estrogenic endocrine-disrupting chemicals and their risk for human reproduction.
Tsutsumi O. J Steroid Biochem Mol Biol. 2005 93(2-5):325-30.

There is broad human exposure to estrogenic endocrine-disrupting chemicals (EDCs), but the data sets that exist are primarily for various environmental media such as food and water rather than the most relevant internal exposure. We have detected various kind of EDC contamination in humans including dioxin and bisphenol A (BPA) widely used for the production of plastic products. BPA was present in serum and follicular fluid at approximately 1-2 ng/ml, as well as in fetal serum and full-term amniotic fluid, confirming passage through the placenta. An approximately five-fold higher concentration, 8.3+/-8.7 ng/ml, was revealed in amniotic fluid at 15-18 weeks of gestation, compared to other fluids showing increased exposure at the critical developmental period in humans. Interestingly, serum BPA concentrations were significantly higher in normal men and in women with polycystic ovary syndrome (PCOS) compared with normal women possibly due to differences in the androgen-related metabolism of BPA. These findings may provide some insight into the metabolism of EDCs in human and the pathophysiology of endocrine disorders such as PCOS. Dioxin contamination in relationship to development of endometriosis is also discussed.

9. Development and function of naturally occurring CD4+CD25+ regulatory T cells.
Toda A, Piccirillo CA. J Leukoc Biol. 2006 80(3):458-70.
{free online} http://www.jleukbio.org/cgi/content/full/80/3/458

10. Naturally occurring self-reactive CD4+CD25+ regulatory T cells: universal immune code.
Pakravan N et al. Cell Mol Immunol. 2007 4(3):197-201.
{free online} http://www.cmi.ustc.edu.cn/4/3/197.pdf

11. CD4+CD25+Foxp3+ regulatory T cells: from basic research to potential therapeutic use.
Mottet C, Golshayan D. Swiss Med Wkly. 2007 Nov 17;137(45-46):625-34.
{free online}
http://www.smw.ch/docs/pdf200x/2007/45/smw-11916.pdf

12. Exposure to bisphenol A during embryonic/fetal life and infancy increases oxidative injury and causes underdevelopment of the brain and testis in mice.
Kabuto H et al. Life Sci. 2004 74(24):2931-40.

We investigated the modifications in endogenous antioxidant capacity and oxidative damage in the brain, liver, kidney and testis in mice exposed to bisphenol A (BPA), an environmental endocrine disrupter. Mice were exposed to BPA throughout embryonic/fetal life and during lactation by feeding their pregnant/lactating mothers BPA at 5 or 10 microg per milliliter of drinking water. At the age of four weeks, male mice were sacrificed. Exposure to BPA increased the activity of catalase and glutathione peroxidase in the liver and kidney, respectively. It also increased thiobarbituric acid-reactive substances in the brain, kidney and testis, and decreased the wet weight of the brain, kidney and testis. Our results suggest that exposure to BPA throughout embryonic/fetal life and during infancy induces tissue oxidative stress and peroxidation, ultimately leading to underdevelopment of the brain, kidney and testis.

13. Effects of bisphenol A on the metabolisms of active oxygen species in mouse tissues.
Kabuto H et al. Environ Res. 2003 Sep;93(1):31-5.

We investigated the modifications in endogenous antioxidant capacity, including superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase, oxidative stress index, reduced glutathione (GSH), glutathione disulfide (GSSG), and thiobarbituric acid-reactive substance (TBARS) in the brain, liver, kidney, and testes of mice under bisphenol A (BPA), an endocrine disrupter, treated for 5 days. BPA was administrated intraperitoneally at doses of 25 and 50mg/kg/day. The TBARS levels were not affected by BPA administrations. The SOD activities increased and the catalase activities decreased in the liver after BPA administration. The GPx activity decreased in the kidney. The levels of GSH+GSSG increased in the brain, kidney, liver, and testes, while, the levels of GSH decreased in the testes. SOD converts superoxide into hydrogen peroxide, and catalase and GPx convert hydrogen peroxide into hydrogen oxide. Our results suggest that the injection of BPA induces overproduction of hydrogen peroxide in the mouse organs. Hydrogen peroxide is easily converted to hydroxy radical. The decrease of GSH and the increase of GSSG may be caused by the hydroxy radical. BPA may show its toxicity by increasing hydrogen peroxide.

14. Glutathione S-transferase polymorphisms and their biological consequences.
Hayes JD, Strange RC. Pharmacology. 2000 Sep;61(3):154-66.

Two supergene families encode proteins with glutathione S-transferase (GST) activity: the family of soluble enzymes comprises at least 16 genes; the separate family of microsomal enzymes comprises at least 6 genes. These two GST families are believed to exert a critical role in cellular protection against oxidative stress and toxic foreign chemicals. They detoxify a variety of electrophilic compounds, including oxidized lipid, DNA and catechol products generated by reactive oxygen species-induced damage to intracellular molecules. An increasing number of GST genes are being recognized as polymorphic. Certain alleles, particularly those that confer impaired catalytic activity (e.g. GSTM1(*)0, GSTT1(*)0), may be associated with increased sensitivity to toxic compounds. GST polymorphisms may be disease modifying; for example, in subgroups of patients with basal cell carcinoma or bronchial hyper-responsiveness, certain GST appear to exert a statistically significant and biologically relevant impact on disease susceptibility.

15. Homozygous gene deletions of the glutathione S-transferases M1 and T1 are associated with thimerosal sensitization.
Westphal GA et al. Int Arch Occup Environ Health. 2000 Aug;73(6):384-8.

16. Metabolic endophenotype and related genotypes are associated with oxidative stress in children with autism.
James SJ et al. Am J Med Genet B Neuropsychiatr Genet. 2006 141B(8):947-56.
{free online}
http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=2610366&blobtype=pdf

Autism is a behaviorally defined neurodevelopmental disorder usually diagnosed in early childhood that is characterized by impairment in reciprocal communication and speech, repetitive behaviors, and social withdrawal. Although both genetic and environmental factors are thought to be involved, none have been reproducibly identified. The metabolic phenotype of an individual reflects the influence of endogenous and exogenous factors on genotype. As such, it provides a window through which the interactive impact of genes and environment may be viewed and relevant susceptibility factors identified. Although abnormal methionine metabolism has been associated with other neurologic disorders, these pathways and related polymorphisms have not been evaluated in autistic children. Plasma levels of metabolites in methionine transmethylation and transsulfuration pathways were measured in 80 autistic and 73 control children. In addition, common polymorphic variants known to modulate these metabolic pathways were evaluated in 360 autistic children and 205 controls. The metabolic results indicated that plasma methionine and the ratio of S-adenosylmethionine (SAM) to S-adenosylhomocysteine (SAH), an indicator of methylation capacity, were significantly decreased in the autistic children relative to age-matched controls. In addition, plasma levels of cysteine, glutathione, and the ratio of reduced to oxidized glutathione, an indication of antioxidant capacity and redox homeostasis, were significantly decreased. Differences in allele frequency and/or significant gene-gene interactions were found for relevant genes encoding the reduced folate carrier (RFC 80G > A), transcobalamin II (TCN2 776G > C), catechol-O-methyltransferase (COMT 472G > A), methylenetetrahydrofolate reductase (MTHFR 677C > T and 1298A > C), and glutathione-S-transferase (GST M1). We propose that an increased vulnerability to oxidative stress (endogenous or environmental) may contribute to the development and clinical manifestations of autism.

17. Risk of autistic disorder in affected offspring of mothers with a glutathione S-transferase P1 haplotype.
Williams TA et al. Arch Pediatr Adolesc Med. 2007 161(4):356-61.
{free online}
http://archpedi.ama-assn.org/cgi/content/full/161/4/356

Objective: To test whether polymorphisms of the glutathione S-transferase P1 gene (GSTP1) act in the mother during pregnancy to contribute to the phenotype of autistic disorder (AD) in her fetus. DESIGN: Transmission disequilibrium testing (TDT) in case mothers and maternal grandparents. SETTING: Autistic disorder may result from multiple genes and environmental factors acting during pregnancy and afterward. Teratogenic alleles act in mothers during pregnancy to contribute to neurodevelopmental disorders in their offspring; however, only a handful have been identified. GSTP1 is a candidate susceptibility gene for AD because of its tissue distribution and its role in oxidative stress, xenobiotic metabolism, and JNK regulation. PARTICIPANTS: We genotyped GSTP1*G313A and GSTP1*C341T polymorphisms in 137 members of 49 families with AD. All probands received a clinical diagnosis of AD by Autism Diagnostic Interview-Revised and Autism Diagnostic Observation Schedule-Generic testing. MAIN OUTCOME MEASURES: Association of haplotypes with AD was tested by the TDT-Phase program, using the expectation-maximization (EM) algorithm for uncertain haplotypes and for incomplete parental genotypes, with standard measures of statistical significance. RESULTS: The GSTP1*A haplotype was overtransmitted to case mothers (P = .01 [P = .03 using permutation testing]; odds ratio, 2.67 [95% confidence interval, 1.39-5.13]). Results of the combined haplotype and genotype analyses suggest that the GSTP1-313 genotype alone determined the observed haplotype effect. CONCLUSIONS: Overtransmission of the GSTP1*A haplotype to case mothers suggests that action in the mother during pregnancy likely increases the likelihood of AD in her fetus. If this is confirmed and is a result of a gene-environment interaction occurring during pregnancy, these findings could lead to the design of strategies for prevention or treatment.

18. Elevated serum bisphenol A levels under hyperandrogenic conditions may be caused by decreased UDP-glucuronosyltransferase activity.
Takeuchi T et al. Endocr J. 2006 Aug;53(4):485-91. Epub 2006 Jul 10.

This study was performed to investigate the effect of androgen on the metabolism of bisphenol A (BPA), an endocrine disruptor, in order to clarify the mechanism of the higher levels of serum BPA in men and hyperandrogenemic women compared with normal women. Castrated female rats (OVX) were subcutaneously injected with testosterone propionate (TP) (0.01, 0.1, and 1 mg) every day for 2 weeks. Serum BPA concentrations in OVX rats showed a TP dose-dependent increase and were significantly higher at 0.1 and 1.0 mg of TP. The enzyme reaction of BPA glucuronidation in the rat liver microsomes showed that the ratio of glucuronide in the OVX rats was significantly reduced in a TP dose-dependent manner. Analysis of the mRNA expression of UDP-glucuronosyltransferase 2B1 (UGT2B1) by real-time quantitative RT-PCR revealed that the relative expression level of UGT2B1 mRNA showed a TP dose-dependent decrease. The results of enzyme analyses demonstrated that the ratio of BPA glucuronidation and the expression level of UGT2B1 mRNA were significantly lower under the hyperandrogenemic conditions. The clearance of BPA may be slowed in a TP dose-dependent manner, resulting in an increase of serum BPA concentration under hyperandrogenemic conditions.

19. Positive relationship between androgen and the endocrine disruptor, bisphenol A, in normal women and women with ovarian dysfunction.
Takeuchi T et al. Endocr J. 2004 Apr;51(2):165-9.
{free online}
http://www.jstage.jst.go.jp/article/endocrj/51/2/51_165/_article

This study was performed to investigate the serum levels of bisphenol A (BPA), an endocrine disruptor, in women with ovarian dysfunction and obesity. Fasting serum samples were obtained from 19 non-obese and 7 obese women with normal menstrual cycles: 7 patients with hyperprolactinemia, 21 patients with hypothalamic amenorrhea, and 13 non-obese and 6 obese patients with polycystic ovary syndrome (PCOS). BPA was measured by an enzyme-linked immunosorbent assay. BPA was detected in all human sera. Serum BPA concentrations were significantly higher in both non-obese and obese women with polycystic ovary syndrome (1.05 +/- 0.10 ng/ml, 1.17 +/- 0.16 ng/ml; p<0.05, respectively) and obese normal women (1.04 +/- 0.09 ng/ml, p<0.05) compared with those in non-obese normal women (0.71 +/- 0.09 ng/ml). There was no difference among women with hyperprolactinemia, women with hypothalamic amenorrhea, and non-obese normal women. There were significant positive correlations between serum BPA and total testosterone (r = 0.391, p<0.001), free testosterone (r = 0.504, p<0.001), androstenedione (r = 0.684, p<0.001), and DHEAS (r = 0.514, p<0.001) concentrations in all subjects. These findings show that there is a strong relationship between serum BPA and androgen concentrations, speculatively due to the effect of androgen on the metabolism of BPA.

20. Elevated serum bisphenol A levels under hyperandrogenic conditions may be caused by decreased UDP-glucuronosyltransferase activity.
Takeuchi T et al. Endocr J. 2006 53(4):485-91.
{free online}
http://www.jstage.jst.go.jp/article/endocrj/53/4/53_485/_article

This study was performed to investigate the effect of androgen on the metabolism of bisphenol A (BPA), an endocrine disruptor, in order to clarify the mechanism of the higher levels of serum BPA in men and hyperandrogenemic women compared with normal women. Castrated female rats (OVX) were subcutaneously injected with testosterone propionate (TP) (0.01, 0.1, and 1 mg) every day for 2 weeks. Serum BPA concentrations in OVX rats showed a TP dose-dependent increase and were significantly higher at 0.1 and 1.0 mg of TP. The enzyme reaction of BPA glucuronidation in the rat liver microsomes showed that the ratio of glucuronide in the OVX rats was significantly reduced in a TP dose-dependent manner. Analysis of the mRNA expression of UDP-glucuronosyltransferase 2B1 (UGT2B1) by real-time quantitative RT-PCR revealed that the relative expression level of UGT2B1 mRNA showed a TP dose-dependent decrease. The results of enzyme analyses demonstrated that the ratio of BPA glucuronidation and the expression level of UGT2B1 mRNA were significantly lower under the hyperandrogenemic conditions. The clearance of BPA may be slowed in a TP dose-dependent manner, resulting in an increase of serum BPA concentration under hyperandrogenemic conditions.

21. Serum bisphenol a concentrations showed gender differences, possibly linked to androgen levels.
Takeuchi T, Tsutsumi O. Biochem Biophys Res Commun. 2002 291(1):76-8.

To investigate human exposure to bisphenol A (BPA), a widely used endocrine disruptor, we measured serum BPA concentrations and analyzed the interrelation of BPA with sex-related hormones. BPA was detected in all human sera by a novel enzyme-linked immunosorbent assay. Serum BPA concentrations were significantly higher in normal men (1.49 +/- 0.11 ng/ml; P < 0.01) and in women with polycystic ovary syndrome (1.04 +/- 0.10 ng/ml; P < 0.05) compared with normal women (0.64 +/- 0.10 ng/ml). There were significant positive correlations between serum BPA and total testosterone (r = 0.595, P < 0.001) and free testosterone (r = 0.609, P < 0.001) concentrations in all subjects and likewise between serum BPA and total testosterone (r = 0.559, P < 0.01) and free testosterone (r = 0.598, P < 0.001) concentrations in all female subjects, but not between serum BPA and other sex-related hormone concentrations in any group. These findings showed that there are gender differences in serum BPA concentrations, possibly due to differences in the androgen-related metabolism of BPA.

22. A clinical and laboratory evaluation of methionine cycle-transsulfuration and androgen pathway markers in children with autistic disorders.
Geier DA, Geier MR. Horm Res. 2006;66(4):182-8.

BACKGROUND/AIMS: The prevalence of autism spectrum disorders (ASDs) is 1 in 300 children in the US. ASDs are characterized by impairments in social relatedness and communication, repetitive behaviors, abnormal movement patterns, and sensory dysfunction. Pre-pubertal age children with ASDs were assessed for metabolites in the methionine cycle-transsulfuration and androgen pathways, and for present physical development/behaviors indicative of hyperandrogenicity. METHODS: The Institutional Review Board of the Institute for Chronic Illnesses (Office for Human Research Protections, US Department of Health and Human Services IRB number: IRB00005375) approved the present study. Sixteen consecutive pre-pubertal age children (

23. Spironolactone might be a desirable immunologic and hormonal intervention in autism spectrum disorders.
Bradstreet JJ et al. Med Hypotheses. 2007;68(5):979-87. Epub 2006 Dec 5.

Multiple studies now demonstrate that autism is medically characterized, in part, by immune system dysregulation, including evidence of neuroglial activation and gastrointestinal inflammation. This neuroglial process has further been characterized as neuroinflammation. In addition, a subset of autistic children exhibit higher than average levels of androgens. Spironolactone is an aldosterone antagonist and potassium-sparing diuretic with a desirable safety profile. It possesses potent anti-inflammatory and immune modifying properties that might make it an excellent medical intervention for autism spectrum disorders. Furthermore, spironolactone demonstrates substantial anti-androgen properties that might further enhance its appeal in autism, particularly in a definable subset of hyperandrogenic autistic children. One case report is briefly reviewed demonstrating objective clinical improvements in an autistic child after spironolactone administration. Additional research in controlled trials is now needed to further define the risks and benefits of spironolactone use in children with autism.

24. Control of NK cell functions by CD4+CD25+ regulatory T cells.
Ralainirina N et al. J Leukoc Biol. 2007 Jan;81(1):144-53.
{free online}
http://www.jleukbio.org/cgi/content/full/81/1/144

Regulatory T cells (Treg) are key players in the maintenance of peripheral tolerance. As a result of suppressive effects on CD4+ and CD8+ effector T cells, Treg control the adaptive immune system and prevent autoimmunity. In addition, they inhibit B lymphocytes, dendritic cells, and monocytes/macrophages. It is interesting that several recent papers show that CD4+CD25+ Treg are also able to inhibit NK cells. Thus, Treg exert their control on immune responses from the onset (triggering of innate immune cells) to the effector phase of adaptive immunity (B and T cell-mediated responses). That Treg inhibit NK cells suggests that their uncontrolled activation might break self-tolerance and induce "innate" autoimmune pathology. Conversely, Treg-mediated suppression of NK cell functions might have negative effects, as these cells are important in defense against infections and cancer. It is conceivable that Treg might dampen efficient activation of NK cells in these diseases.

25. Reduced natural killer cell activity in autism.
Warren RP et al. J Am Acad Child Adolesc Psychiatry. 1987 26(3):333-5

26. Low natural killer cell cytotoxic activity in autism: the role of glutathione, IL-2 and IL-15.
Vojdani A et al. J Neuroimmunol. 2008 Dec 15;205(1-2):148-54.

Although many articles have reported immune abnormalities in autism, NK cell activity has only been examined in one study of 31 patients, of whom 12 were found to have reduced NK activity. The mechanism behind this low NK cell activity was not explored. For this reason, we explored the measurement of NK cell activity in 1027 blood samples from autistic children obtained from ten clinics and compared the results to 113 healthy controls. This counting of NK cells and the measurement of their lytic activity enabled us to express the NK cell activity/100 cells. At the cutoff of 15-50 LU we found that NK cell activity was low in 41-81% of the patients from the different clinics. This NK cell activity below 15 LU was found in only 8% of healthy subjects (p<0.001). Low NK cell activity in both groups did not correlate with percentage and absolute number of CD16(+)/CD56(+) cells. When the NK cytotoxic activity was expressed based on activity/100 CD16(+)/CD56(+) cells, several patients who had displayed NK cell activity below 15 LU exhibited normal NK cell activity. Overall, after this correction factor, 45% of the children with autism still exhibited low NK cell activity, correlating with the intracellular level of glutathione. Finally, we cultured lymphocytes of patients with low or high NK cell activity/cell with or without glutathione, IL-2 and IL-15. The induction of NK cell activity by IL-2, IL-15 and glutathione was more pronounced in a subgroup with very low NK cell activity. We conclude that that 45% of a subgroup of children with autism suffers from low NK cell activity, and that low intracellular levels of glutathione, IL-2 and IL-15 may be responsible.

27. Toll-like receptors and immune regulation: their direct and indirect modulation on regulatory CD4+ CD25+ T cells.
Liu G, Zhao Y. Immunology. 2007 122(2):149-56.
{free online}
http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=2266004&blobtype=pdf

28. Impact of innate immunity in a subset of children with autism spectrum disorders: a case control study.
Jyonouchi H et al. J Neuroinflammation. 2008 Nov 21;5:52.
{free online}
http://www.jneuroinflammation.com/content/5/1/52

BACKGROUND: Among patients with autism spectrum disorders (ASD) evaluated in our clinic, there appears to be a subset that can be clinically distinguished from other ASD children because of frequent infections (usually viral) accompanied by worsening behavioural symptoms and/or loss/decrease in acquired skills. This study assessed whether these clinical features of this ASD subset are associated with atopy, asthma, food allergy (FA), primary immunodeficiency (PID), or innate immune responses important in viral infections. METHODS: This study included the ASD children described above (ASD test, N = 26) and the following controls: ASD controls (N = 107), non-ASD controls with FA (N = 24), non-ASD controls with chronic rhinosinusitis/recurrent otitis media (CRS/ROM; N = 38), and normal controls (N = 43). We assessed prevalence of atopy, asthma, FA, CRS/ROM, and PID. Innate immune responses were assessed by measuring production of proinflammatory and counter-regulatory cytokines by peripheral blood mononuclear cells (PBMCs) in response to agonists of Toll-like receptors (TLRs), with or without pre-treatment of lipopolysaccharide (LPS), a TLR4 agonist. RESULTS: Non-IgE mediated FA was equally prevalent in both ASD test and ASD control groups, occurring at higher frequency than in the non-ASD controls. Allergic rhinitis, atopic/non-atopic asthma, and atopic dermatitis were equally prevalent among the study groups except for the CRS/ROM group in which non-atopic asthma was more prevalent (52.6%). CRS/ROM and specific polysaccharide antibody deficiency (SPAD) were more prevalent in the ASD test group than in the ASD control, FA, and normal control groups: 23.1% vs. < 5% for CRS/ROS and 19.2% vs. < 1% for SPAD. However, CRS/ROM patients had the highest prevalence of SPAD (34.2%). When compared to ASD and normal case controls, PBMCs from 19 non-SPAD, ASD test group children produced: 1) less IL-1beta with a TLR7/8 agonist, less IL-10 with a TLR2/6 agonist, and more IL-23 with a TLR4 agonist without LPS pre-treatment, and 2) less IL-1beta with TLR4/7/8 agonists with LPS pre-treatment. These are cytokines associated with the neuro-immune network. CONCLUSION: Clinical features of the ASD test group were not associated with atopy, asthma, FA, or PID in our study but may be associated with altered TLR responses mediating neuro-immune interactions.