Circulating natural antibodies to inflammatory cytokines are potential biomarkers for atherosclerosis

Autoantibodies to Interferons in Infectious Diseases

Anti-cytokine autoantibodies and, in particular, anti-type I interferons are increasingly described in association with immunodeficient, autoimmune, and immune-dysregulated conditions. Their presence in otherwise healthy individuals may result in a phenotype characterized by a predisposition to infections with several agents. For instance, anti-type I interferon autoantibodies are implicated in Coronavirus Disease 19 (COVID-19) pathogenesis and found preferentially in patients with critical disease. However, autoantibodies were also described in the serum of patients with viral, bacterial, and fungal infections not associated with COVID-19. In this review, we provide an overview of anti-cytokine autoantibodies identified to date and their clinical associations; we also discuss whether they can act as enemies or friends, i.e., are capable of acting in a beneficial or harmful way, and if they may be linked to gender or immunosenescence. Understanding the mechanisms underlying the production of autoantibodies could improve the approach to treating some infections, focusing not only on pathogens, but also on the possibility of a low degree of autoimmunity in patients.

Further analysis of natural antibodies against ischemic stroke

Background

Our previous study revealed that circulating levels of IgG natural antibodies (NAbs) for vascular endothelial growth factor receptor 1 (VEGFR1) were significantly decreased in patients with arteriosclerosis compared with control subjects. To enhance the sensitivity of an enzyme-linked immunosorbent assay (ELISA) developed in-house for antibody testing, the present work was designed to investigate additive signals in the in-house ELISA developed with the combination of two or more linear peptide antigens derived from target proteins of interest, including VEGFR1, oxidized low-density lipoprotein receptor 1 (LOX-1), interleukins 6 (IL6) and 8 (IL8).

Methods

A total of 218 patients with ischemic stroke and 198 healthy controls were enrolled and an in-house ELISA was developed with linear peptides derived from VEGFR1, LOX-1, IL6, and IL8 to detect their IgG levels in plasma.

Results

Compared with control subjects, plasma levels of IgG NAbs for the IL6-IL8 combination were significantly lower in female patients (Z = -3.149, P = 0.002), whereas male patients showed significantly lower levels of plasma anti-VEGFR IgG (Z = -3.895, P < 0.001) and anti-LOX1a IgG (Z = -4.329, P < 0.001). Because plasma levels of IgG NAbs for both the IL6-IL8-LOX1a-LOX1b combination and the VEGFR1a-VEGFR1b-LOX1a-LOX1b combination were significantly lower in the patient group than the control group, receiver operating characteristic (ROC) analysis was performed and the results showed that the VEGFR1a-VEGFR1b-LOX1a-LOX1b combination had an area under the ROC curve (AUC) of 0.70 for its IgG assay with a sensitivity of 27.1% against the specificity of 95.5% and that the IL6-IL8-LOX1a-LOX1b combination had an AUC of 0.67 for its IgG assay with a sensitivity of 21.1% against the specificity of 95.5%. Spearman correlation analysis showed that plasma IgG NAbs against the IL6-IL8 combination were positively correlated with carotid plaque size only in male patients (r = 0.270, p = 0.002).

Conclusions

Circulating IgG NAbs for the target molecules studied may be potential biomarkers for a subgroup of ischemic stroke and also contribute to the gender differences in clinical presentation of the disease.

Circulating Natural Autoantibodies to HER2-Derived Peptides Performed Antitumor Effects on Oral Squamous Cell Carcinoma

Natural autoantibodies play a crucial role in destruction of malignant tumors due to immune surveillance function. Epidermal growth factor receptor 2 (HER2) has been found to be highly expressed in a variety of epithelial tumors including oral squamous cell carcinoma (OSCC). The present study was thus undertaken to investigate the effect of anti-HER2 natural autoantibodies on OSCC. Compared with cancer-adjacent tissues, cancer tissues from OSCC patients exhibited higher HER2 expression especially in those with middle & advanced stage OSCC. Plasma anti-HER2 IgG levels examined with an enzyme-linked immunosorbent assay (ELISA) developed in-house showed differences between control subjects, individuals with oral benign tumor and patients with OSCC. In addition, anti-HER2 IgG-abundant plasma was screened from healthy donors to treat OSCC cells and to prepare for anti-HER2 intravenous immunoglobulin (IVIg). Both anti-HER2 IgG-abundant plasma and anti-HER2 IVIg could significantly inhibit proliferation and invasion of OSCC cells by inducing the apoptosis, and also regulate apoptosis-associated factors and epithelial-mesenchymal transition (EMT), respectively. Besides, the complement-dependent cytotoxicity (CDC) pathway was likely to contribute to the anti-HER2 IgG mediated inhibition of OSCC cells. After the HER2 gene was knocked down with HER2-specific siRNAs, the inhibitory effects on OSCC cell proliferation and apoptotic induction faded away. In conclusion, human plasma IgG, or IVIg against HER2 may be a promising agent for anti-OSCC therapy.

Downregulation of G3BP2 reduces atherosclerotic lesions in ApoE-/- mice

BACKGROUND AND AIMS

Atherosclerosis is mainly caused by stress in arterial microenvironments, which results in the formation of stress granules as a consequence of the stress response. As the core protein of stress granules, GTPase-activating protein (SH3 domain)-binding protein 2 (G3BP2) is known to play pivotal roles in tumour initiation, viral infection and Alzheimer's disease, but the role of G3BP2 in atherosclerosis development is poorly understood. Previous studies have shown that vaccination with epitopes from self-antigens could reduce atherosclerotic lesions. Here, we investigated the effect of immunizing ApoE^-/- mice with G3BP2 peptides, and whether this immunization exerted an anti-atherogenic effect.

METHODS AND RESULTS

In our study, ApoE^-/- mice were fed a high-fat diet for 12 weeks from 8 to 20 weeks of age. Then, using a repetitive multiple site strategy, the mice were immunized with a Keyhole limpet haemocyanin (KLH) conjugated G3BP2 peptide for 2 weeks from weeks 16 to 18. High levels of G3BP2 antibodies were detectable before sacrifice. Histological analyses showed that the number of atherosclerotic lesions in ApoE^-/- mice was significantly reduced following G3BP2 immunotherapy. The levels of pro-inflammatory cytokines and macrophages were also greatly decreased, while the collagen content of the plaques showed significant increase. Furthermore, knocking down G3BP2 in ApoE^-/- mice reduced the number of lesions compared to ApoE^-/- mice fed a high-fat diet for eight weeks. In vitro studies demonstrated that G3BP2 regulated ox-LDL-induced inflammation in HUVECs via controlling the localization of IκBα.

CONCLUSIONS

Immunization with the G3BP2 peptide antigen or knocking down of G3BP2 significantly decreased early atherosclerotic plaques in the ApoE^-/- mouse model of atherosclerosis. G3BP2 is a promising potential target for atherosclerosis therapy.

Analysis of plasma autoantibodies for inflammatory cytokines in patients with first-episode schizophrenia among a Chinese population

Neuroinflammation has been considered to be involved in the development of schizophrenia. This study aimed to study circulating autoantibodies for inflammatory cytokines in first-episode schizophrenia. A total of 181 patients and 197 controls were recruited for detection of plasma IgG antibodies against peptide antigens derived from interleukin 1α (IL1α), IL1ß, IL6, IL8 and tumour necrosis factor alpha (TNFα). The major finding was that patients with schizophrenia had significantly higher levels of anti-IL1ß IgG, anti-IL6 IgG and anti-IL8 IgG, and a significantly lower level of anti-IL1α IgG. This study suggests that inflammatory response may contribute to the development of schizophrenia.