Inflammation is closely associated with cerebrovascular diseases, cardiovascular diseases, diabetes, and cancers, and it is accompanied by the development of autoantibodies in the early stage of inflammation-related diseases. Hence, it is meaningful to discover novel antibody biomarkers targeting inflammation-related diseases. In this study, Jumonji C-domain-containing 6 (JMJD6) was identified by the serological identification of antigens through recombinant cDNA expression cloning. In particular, JMJD6 is an antigen recognized in serum IgG from patients with unstable angina pectoris (a cardiovascular disease). Then, the serum antibody levels were examined using an amplified luminescent proximity homogeneous assay-linked immunosorbent assay and a purified recombinant JMJD6 protein as an antigen. We observed elevated levels of serum anti-JMJD6 antibodies (s-JMJD6-Abs) in patients with inflammation-related diseases such as ischemic stroke, acute myocardial infarction (AMI), diabetes mellitus (DM), and cancers (including esophageal cancer, EC; gastric cancer; lung cancer; and mammary cancer), compared with the levels in healthy donors. The s-JMJD6-Ab levels were closely associated with some inflammation indicators, such as C-reactive protein and intima–media thickness (an atherosclerosis index). A better postoperative survival status of patients with EC was observed in the JMJD6-Ab-positive group than in the negative group. An immunohistochemical analysis showed that JMJD6 was highly expressed in the inflamed mucosa of esophageal tissues, esophageal carcinoma tissues, and atherosclerotic plaques. Hence, JMJD6 autoantibodies may reflect inflammation, thereby serving as a potential biomarker for diagnosing specific inflammation-related diseases, including stroke, AMI, DM, and cancers, and for prediction of the prognosis in patients with EC.

The relationship between energy production and cancer is attracting attention. This study aimed to investigate the clinicopathological significance of fumarate hydratase (FH), a tricarboxylic acid cycle enzyme, in gastric cancer using autoantibodies as biomarkers. The study analyzed 116 patients who underwent gastric cancer surgery and 96 healthy controls. Preoperative serum FH autoantibody (s-FH-Ab) titers were analyzed using an immunosorbent assay with an amplified luminescent proximity homogeneous assay. Receiver operating characteristic analysis was used to determine the cutoff s-FH-Ab titer. Clinicopathological factors and prognosis were compared between the high and low s-FH-Ab groups. The s-FH-Ab levels were significantly higher in the gastric cancer group than in the control group (p = 0.01). Levels were elevated even in patients with stage I gastric cancer compared with healthy controls (p = 0.02). A low s-FH-Ab level was significantly associated with distant metastasis (p = 0.01), peritoneal dissemination (p < 0.05), and poor overall survival (p < 0.01). Multivariate analysis revealed that low s-FH-Ab levels were an independent risk factor for poor prognosis (p < 0.01). Therefore, s-FH-Ab levels may be a useful biomarker for early diagnosis and the prediction of prognosis in patients with gastric cancer.

Background: Given the highly aggressive nature of gastrointestinal cancers, the identification of novel biomarkers for diagnosis and prognosis is of considerable clinical importance. Methods: Candidate cancer-testis (CT) antigens were first screened using RNA-sequencing data from normal human tissues; candidates showing high commonality across tumor RNA-sequencing datasets publicly available in The Cancer Genome Atlas were subsequently prioritized, and POTEE was identified as a promising target. Recombinant POTEE protein was expressed in Escherichia coli, purified by affinity chromatography, and used as the antigen for serological analysis. Results: Serum levels of anti-POTEE antibodies (s-POTEE-Abs) were significantly elevated in 121 patients with esophageal squamous cell carcinoma, 62 patients with gastric adenocarcinoma, and 158 patients with colorectal adenocarcinoma compared with those in 96 healthy donors. Receiver operating characteristic curve analysis showed that the diagnostic performance of s-POTEE-Ab was comparable to that of s-p53-Ab, with area under the curve values of 0.832 versus 0.829 in esophageal squamous cell carcinoma, 0.680 versus 0.698 in gastric adenocarcinoma, and 0.735 versus 0.706 in colorectal adenocarcinoma, respectively. In survival analyses, s-POTEE-Ab positivity was associated with poorer overall survival in ESCC and CRAC, but not in GAC. After multivariable adjustment, an independent prognostic association was retained only in CRAC. Conclusions: These findings suggest that s-POTEE-Ab may represent a promising exploratory serological biomarker for gastrointestinal cancers. Its prognostic relevance appears to be cancer-type dependent and requires further validation in independent cohorts.

Aim: Atherosclerosis and diabetes mellitus (DM) often lead to severe conditions, such as acute ischemic stroke (AIS), cardiovascular disease (CVD), and chronic kidney disease (CKD). Some cancers are also associated with atherosclerosis. Therefore, identifying novel autoantibody biomarkers associated with atherosclerosis-related conditions is crucial for improving early diagnosis and risk assessment. Methods: We used an array of 9,480 proteins to detect IgG antibodies in the serum of patients with atherosclerosis. Following this screening, we quantified the antibody levels using an amplified luminescent proximity homogeneous assay-linked immunosorbent assay (AlphaLISA) with recombinant antigen proteins. Results: Ubiquitin conjugating enzyme E2 E3 (UBE2E3) was identified as a candidate antigen recognized by IgG antibodies in the sera of individuals diagnosed with atherosclerosis. Compared with healthy donors, significantly higher serum antibody levels against UBE2E3 were found in patients with AIS, DM, CVD, CKD, esophageal cancer (EC), and gastric cancer (GC), but not in those with colorectal cancer (CRC). Receiver operating characteristic (ROC) analysis revealed that the higher areas under the ROC curves for anti-UBE2E3 antibodies were observed in DM- or nephrosclerosis-associated CKD than in the others. Spearman’s correlation analysis revealed that serum anti-UBE2E3 antibody (s-UBE2E3-Ab) levels were associated with the plaque score, maximum intima-media thickness, and cardio-ankle vascular index, which are typical indices of atherosclerosis and stenosis. In the survival analysis of GC and CRC, patients who were s-UBE2E3-Ab-positive had significantly poorer prognoses than patients who were s-UBE2E3-Ab-negative. The difference became more prominent when s-UBE2E3-Abs were combined with anti-differential screening-selected gene aberrant in neuroblastoma antibody (DAN-Ab) or sclerostin domain-containing protein 1 (SOSTDC1), which are bone morphogenetic protein (BMP) antagonists. Conclusions: The s-UBE2E3-Ab marker is highly associated with atherosclerosis-related diseases, such as AIS, CVD, DM, CKD, and digestive tract cancers, suggesting the involvement of BMP signals.

Background: Metabolic reprogramming toward aerobic glycolysis, commonly referred to as the Warburg effect, is a hallmark of cancer. Such metabolic alterations may lead to aberrant expression and release of glycolytic and mitochondrial proteins, which can act as tumor-associated antigens and elicit humoral immune responses. However, whether patients with esophageal carcinoma (EC) develop a broad autoantibody response against these metabolic proteins, and whether such an autoantibody profile has diagnostic or prognostic relevance, has not been systematically investigated. Objective: To determine (1) whether serum autoantibodies against 18 proteins involved in glucose metabolism and mitochondrial pathways are broadly elevated in patients with EC and have diagnostic potential; (2) whether combining selected autoantibodies improves diagnostic discrimination; and (3) whether individual or combined autoantibody profiles show exploratory associations with postoperative overall survival. Methods: Serum autoantibody levels against 18 metabolic proteins (SLC2A1, ASPSCR1, GK2, ALDOA, TPI1, GAPDH, PGK1, PGK2, ENO1, PGAM1, PKM, PDHB, PCK1, LDHA, SDHB, FH, IDH, and ATP5B) were measured in 191 patients with EC and 96 healthy donors using AlphaLISA. For diagnostic combination analysis, a multivariable logistic regression model combining ENO1-Ab, PDHB-Ab, and ALDOA-Ab was evaluated in the complete-case cohort. In 91 surgically treated patients, exploratory overall survival analyses were performed using Kaplan–Meier curves and log-rank tests after dichotomization of antibody levels. Results: All 18 autoantibodies were significantly elevated in patients with EC compared with healthy donors (all P < 0.05), with individual AUC values ranging from 0.593 for SDHB-Ab to 0.735 for ENO1-Ab. The three-autoantibody model combining ENO1-Ab, PDHB-Ab, and ALDOA-Ab achieved an AUC of 0.812 (95% CI, 0.751–0.873), with a sensitivity of 68.1% and a specificity of 83.9%, and showed significantly greater diagnostic discrimination than the individual autoantibodies evaluated in the same cohort. In exploratory postoperative overall survival analyses, PCK1-Ab and SDHB-Ab showed significant differences in overall survival by log-rank testing. Several combined autoantibody profiles were also associated with survival differences, including high ENO1-Ab/low PGAM1-Ab, high SDHB-Ab/low FH-Ab, high ALDOA-Ab/high TPI1-Ab, and high PCK1-Ab/high SDHB-Ab versus low PCK1-Ab/low SDHB-Ab. Conclusions: The consistent elevation of autoantibodies against all 18 evaluated metabolic proteins suggests the presence of a broad humoral immune response to metabolic antigens in patients with EC. A three-autoantibody model combining ENO1-Ab, PDHB-Ab, and ALDOA-Ab improved diagnostic discrimination compared with individual markers. Exploratory analyses also identified individual and combined autoantibody profiles associated with postoperative overall survival, warranting further validation in independent cohorts.