Experimental evidence for alpha enolase as one potential autoantigen in the pathogenesis of both autoimmune thyroiditis and its related encephalopathy

The role of thyroid-stimulating hormone in regulating lipid metabolism: Implications for body-brain communication

Thyroid-stimulating hormone (TSH) is a pituitary hormone that stimulates the thyroid gland to produce and release thyroid hormones, primarily thyroxine and triiodothyronine. These hormones are key players in body-brain communication, influencing various physiological processes, including the regulation of metabolism (both peripheral and central effects), feedback mechanisms, and lipid metabolism. Recently, the increasing incidence of abnormal lipid metabolism has highlighted the link between thyroid function and lipid metabolism. Evidence suggests that TSH can affect all bodily systems through body-brain communication, playing a crucial role in growth, development, and the regulation of various physiological systems. Lipids serve dual purposes: they are involved in energy storage and metabolism, and they act as vital signaling molecules in numerous cellular activities, maintaining overall human health or contributing to various diseases. This article reviews the role of TSH in regulating lipid metabolism via body-brain crosstalk, focusing on its implications for common lipid metabolism disorders such as obesity, atherosclerosis, nonalcoholic fatty liver disease, neuropsychiatric disorders (including Alzheimer's disease, Parkinson's disease, multiple sclerosis, epilepsy, and depression), and cerebrovascular disorders such as stroke.

Brain disorders in euthyroid Hashimoto's thyroiditis patients

Hashimoto's thyroiditis (HT) is an autoimmune disorder characterized by the destruction of thyroid follicular cells by thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TgAb), leading to hypothyroidism. Hashimoto's encephalopathy (HE) is associated with elevated levels of antithyroid antibodies. An important question is whether brain alterations precede the development of HE and are present in euthyroid patients with HT, and what pathomechanisms could be responsible for these changes. A PubMed search was conducted to identify studies addressing this issue. Numerous questionnaire studies confirmed impairments in cognitive functioning, mental and physical health, and overall well-being in euthyroid HT patients. Additionally, some imaging and mouse model studies indicate that euthyroid patients with HT likely have central nervous system alterations. Antibodies may be involved in the development of these changes. Some research suggests the role of TPOAb and TgAb, while other studies highlight the involvement of coexisting antibodies. Determining whether antibodies are assessed in serum or cerebrospinal fluid (CSF) is crucial. Antibody-specific indices (ASIs) can differentiate between antibodies passively diffusing from the serum and brain-derived antibodies, and could serve as biomarkers for brain alterations in HT patients. Much more research is needed to identify reliable biomarkers and treatments that could improve the quality of life for these patients.

Determination of the Predictive Roles and Potentially Pathogenic Antigen Epitopes of α-Enolase Related to the Development of Miscarriage in Females with Autoimmune Thyroiditis

Autoimmune thyroiditis (AIT) is a common endocrine disease which causes a significantly increased risk of miscarriage. Our recent study has shown that the increased ENO1 autoantibody (ENO1Ab) expression in an experimental AIT mouse model was induced by thyroglobulin (Tg) immunization only. In this study, we explored the potential roles of ENO1Ab in miscarriage occurrence among AIT women, and the specific epitopes of ENO1 targeted by ENO1Ab. A total of 432 euthyroid pregnant participants were selected from the project of Subclinical Hypothyroid during Early Pregnancy, including 48 women with AIT and miscarriage, 96 with miscarriage but no AIT, 96 with AIT but no miscarriage, and 192 without either AIT or miscarriage. The enzyme-linked immunosorbent assay was used to determine the serum levels of total IgG against ENO1 and 18 predicted antigen epitopes of ENO1. The results showed that women with AIT and miscarriage had the highest serum levels of ENO1Ab compared to the other groups. Logistic regression analysis showed that the serum ENO1Ab was an independent risk factor for miscarriage, especially among AIT females. The serum level of total IgG against the predicted epitope peptide 6 (i.e., P6 and aa168-183) of ENO1 was significantly increased in women with AIT and miscarriage when compared with those of both the AIT non-miscarriage group and non-AIT miscarriage group. This pilot study suggests that serum ENO1Ab may have a fair predictive value for AIT-related miscarriage, and the autoantibody specific to P6 epitope may especially be more specifically related to this disorder.

The effects of maternal anti-alpha-enolase antibody expression on the brain development in offspring

Anti-alpha-enolase autoantibodies have not only been found to play an important role in autoimmune diseases but also cause neurological damage in adults. In this study, a pregnant mouse model with high serum alpha-enolase (ENO1)-specific antibody (ENO1Ab) was established by immunization with ENO1 protein to explore the effects of maternal circulatory ENO1Ab on the brain development in offspring. The pups showed impaired learning and memory abilities with obviously thinner tight junctions in the brain tissue. IgG deposits colocalized with both ENO1 protein and complement 3 (C3), and the membrane attack complex was obviously detectable in the brain tissues of pups from dams with high serum ENO1Ab expression. Our findings suggest that highly expressed ENO1Ab in the maternal circulation can pass through the blood-placenta-barrier and the compromised blood-brain barrier into the brain tissues of offspring and may cause neurological development impairment mainly through complement-dependent cytotoxicity.

A Predictive Role of Autoantibodies Against the Epitope aa168–183 of ENO1 in the Occurrence of Miscarriage Related to Thyroid Autoimmunity

Objective

The aim of the research is to study the association between the serum levels of autoantibodies against one important epitope (¹⁶⁸FMILPVGAANFREAMR¹⁸³, designated as P6) of α-enolase (ENO1-P6Abs) and miscarriage among euthyroid females with thyroid autoimmunity (TAI).

Methods

Anti-ENO1-P6 total IgG was investigated in 432 euthyroid women, and its four subclasses were analyzed in 184 euthyroid women. The serum FT4, TSH, TgAb, and TPOAb levels were determined using an electrochemiluminescence immunoassay. The serum ENO1-P6Ab and anti-protein disulfide isomerase A3 autoantibody (PDIA3Ab) levels were determined using an enzyme-linked immunosorbent assay.

Results

The serum levels of anti-ENO1-P6 total IgG, IgG2, IgG3, and IgG4 were significantly higher in euthyroid TAI females than in non-TAI controls. Additionally, anti-ENO1-P6 total IgG and its 4 subtypes were all markedly higher in euthyroid TAI females with pregnancy loss than those without miscarriage. Moreover, logistic regression analysis showed that highly expressed anti-ENO1-P6 total IgG, IgG1, IgG2, and IgG3 subtypes in the serum were all independent risk factors for euthyroid TAI-related miscarriage, and its IgG1 was also for non-TAI-related abortion. According to the trend test, the prevalence of miscarriage was increased in a titer-dependent manner with the raised levels of serum anti-ENO1-P6 total IgG and IgG1, IgG2, and IgG3 subtypes among euthyroid TAI females. The receiver operating characteristic curve analysis of anti-ENO1-P6 total IgG and IgG1, IgG2, and IgG3 subclass expressions in the serum for miscarriage prediction in euthyroid TAI females exhibited that the total areas under the curves were 0.773 ± 0.041, 0.761 ± 0.053, 0.827 ± 0.043, and 0.760 ± 0.050, respectively (all P <0.0001). Their corresponding optimal cut-off OD450 values were 0.68 (total IgG), 0.26 (IgG1), 0.97 (IgG2), and 0.48 (IgG3), with sensitivities of 70.8, 87.5, 83.3, and 85.4%, and specificities of 70.8, 59.1, 77.3, and 56.8%, respectively. There was an additive interaction between serum anti-ENO1-P6 and anti-PDIA3 total IgGs on the development of miscarriage (RERI = 23.6, AP = 0.79, SI = 5.37).

Conclusion

The highly expressed ENO1-P6Abs may be important risk factors for euthyroid TAI-related miscarriage. The serum levels of ENO1-P6Abs may become good predictive markers for pregnancy loss in euthyroid TAI females, especially its IgG2 subclass expression.

Identification and validation of serum autoantibodies in children with B-cell acute lymphoblastic leukemia by serological proteome analysis

Background

B-cell acute lymphoblastic leukemia (B-ALL) is the most common malignancy of childhood. Even though significant progresses have been made in the treatment of B-ALL, some pediatric B-ALL have still poor prognosis. The identification of tumor autoantibodies may have utility in early cancer diagnosis and immunotherapy. In this study, we used serological proteome analysis (SERPA) to screen serum autoantibodies of pediatric B-ALL, aiming to contribute to the early detection of B-ALL in children.

Methods

The total proteins from three pooled B-ALL cell lines (NALM-6, REH and BALL-1 cells) were separated using two-dimensional gel electrophoresis (2-DE), which was followed by Western blot by mixed serum samples from children with B-ALL (n=20) or healthy controls (n=20). We analyzed the images of 2-D gel and Western blot by PDQuest software, and then identified the spots of immune responses in B-ALL samples compared with those in control samples. The proteins from spots were identified using mass spectrometry (MS). The autoantibodies against alpha-enolase (α-enolase) and voltage-dependent anion-selective channel protein 1 (VDAC1) were further validated in sera from another 30 children with B-ALL and 25 normal individuals by the use of enzyme-linked immunosorbent assay (ELISA). The protein expression levels of the candidate antigens α-enolase and VDAC1 in B-ALL were thoroughly studied by immunohistochemical analysis.

Results

Utilizing the SERPA approach, α-enolase and VDAC1 were identified as candidate autoantigens in children with B-ALL. The frequencies of autoantibodies against α-enolase and VDAC1 in children with B-ALL were 27% and 23% by using ELISA analysis, respectively, which were significantly higher than those in normal controls (4% and 0, p<0.05). Immunohistochemical analysis showed the expression of α-enolase and VDAC1 was positive in 95% and 85% of B-ALL patients, respectively, but negative expression levels were showed in the control group.

Conclusions

This study incidated that α-enolase and VDAC1 may be the autoantigens associated with B-ALL. Therefore, α-enolase and VDAC1 autoantibodies may be the potential serological markers for children with B-ALL.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12953-021-00184-w.