M2 Antibody Research Articles

Neonatal lupus erythematosus successfully treated by exchange transfusion: a case report and literature review

IntroductionThere are few reports of severe hematological involvement in children with neonatal lupus erythematosus (NLE) treated with exchange transfusion. In this case report, we present a female patient with NLE admitted to the Children's Hospital of Soochow University. The main clinical manifestations were pancytopenia and congenital heart block (CHB). Her condition was serious and could not be improved by conventional treatment; however, she responded well to exchange transfusion therapy.Case presentationA female infant, aged 1 month and 3 days, was admitted to the Children's Hospital of Soochow University owing to the “discovery of thrombocytopenia over 1 month.” She tested positive for anti-SSA IgG, anti-Ro-52 IgG, and anti-mitochondrial M2 antibodies. In contrast, her mother tested positive for ANA (1:320) and anti-Ro/SSA antibodies. The patient was diagnosed with NLE and presented with pancytopenia and CHB. Her cardiac function was normal and no intervention was performed; however, her hematological involvement was more severe, without significant improvement after steroid, intravenous immunoglobulin, and transfusion treatments. After exchange transfusion therapy, the patient significantly improved, and the short-term follow-up prognosis was good.ConclusionFor patients with NLE presenting with hematological involvement that cannot be improved by conventional treatment or whose condition is serious, exchange transfusion therapy should be considered to reduce antibody titers and improve their condition.

Proangiogenic effect of thyrotropin receptor stimulating antibody in human umbilical vein endothelial cells.

This study aims to investigate the role of TRAb in the angiogenesis associated with Graves' disease (GD) and to elucidate its underlying mechanisms. Human thyroid follicular epithelial cells (Nthy-ori 3-1) and human umbilical vein endothelial cells (HUVECs) were treated with the monoclonal thyroid-stimulating antibody M22 and thyroid-stimulating hormone (TSH) at various concentrations. Cell viability, migration, and tube formation were evaluated using CCK-8, wound healing, and tube formation assays, respectively. Protein expressions of TSHR receptor (TSHR) and phosphorylated AKT (p-AKT) in M22-induced HUVECs were quantified via Western blotting. Proteomic analysis was employed to identify changes in protein expression profiles and relevant signaling pathways in GD specimens. Immunofluorescence assays were conducted to detect and localize the expressions of CD34 and PROX1 in GD specimens and normal thyroid tissues. M22 stimulated the proliferation of Nthy-ori 3-1 cells and HUVECs in a dose-dependent manner, while TSH exhibited an inverted U-shaped dose-response effect. M22 also dose-dependently promoted angiogenesis, and more effectively induced tube formation in HUVECs compared to TSH, although the difference was not statistically significant. A total of 16 proteins were significantly upregulated and 24 were downregulated in M22-induced HUVECs. Notably, PROX1, the most significantly upregulated protein, is closely associated with angiogenesis. Immunofluorescence confirmed that PROX1 was significantly more expressed in thyroid tissues from GD patients compared to normal tissues adjacent to papillary thyroid cancer (PTC), and it co-localized with CD34. TRAb enhances angiogenesis and upregulates PROX1 expression in HUVECs, suggesting a novel possible mechanism for goiter formation in GD.

Distribution characteristics of antinuclear antibodies in Guillain-Barré syndrome and its relationship with disease severity

BackgroundGuillain-Barré syndrome (GBS), an acquired immune-mediated autoimmune disorder affecting the peripheral nervous system (PNS), is associated with autoimmunity. The presence of autoantibodies in the blood is an important feature of autoimmune diseases. Herein, we explored the distribution characteristics of the antinuclear antibodies (ANAs) in GBS and the correlation between ANAs and disease severity. Materials and methodsWe retrospectively analyzed the clinical data of 170 GBS patients. According to ANAs, GBS patients were divided into ANAs positive and negative groups. The clinical characteristics of these two groups were compared. The distribution difference was also compared between male and female GBS patients. In addition, all enrolled patients were divided into more severe group and milder group according to whether the Hughes score at nadir ≥ 3 or not. Gender, age, and ANAs were compared between the two groups. ResultsIn this study, the positive rate of ANAs was 27.1 % in 170 GBS patients, among which anti-SSA-52/Ro52 antibody and antimitochondrial antibody M2 made up the largest proportion. In the ANAs positive group, GBS patients had longer days of hospitalization, more respiratory function involvement, and higher level of CSF IgG than the ANAs negative group. Compared to the ANAs negative group, Medical Research Council (MRC) scores on admission and at nadir were lower, and Hughes functional Grading Scale (HFGS) scores on admission and at nadir were higher in GBS patients with ANAs positive group. Erasmus GBS Respiratory Insufficiency Score (EGRIS) in ANAs positive GBS patients group was significantly higher than ANAs negative group. Gender had no effects on the distribution of ANAs in GBS patients. Moreover, we found that the anti-SSA-60 antibodies and age were positively correlated with GBS severity. In addition, in the anti-SSA-60 antibody positive group, GBS patients had longer days of hospitalization, more respiratory function involvement, higher HFGS scores on admission/at nadir, and lower MRC scores at nadir compared with the anti-SSA-60 antibody negative group. ConclusionAnti-SSA-52/Ro52 antibody and antimitochondrial antibody M2 were the most common ANAs in GBS patients. Anti-SSA-60 antibodies and age positively correlated with GBS severity. Positive anti-SSA-60 antibodies and age were independent predictors of GBS patient severity.

Clinical Performance of the Line Immunoassay and Digital Liquid Chip Method for Detecting Autoimmune Liver Disease Autoantibodies.

The identification of autoantibodies associated with autoimmune liver disease (ALD) is crucial for diagnosis and management. Various laboratory methods have been introduced to detect autoantibody profiles. However, the variable performance of these assays may create challenges for clinicians and patients. To investigate the concordance rates and diagnostic performance of 2 commercially available assays, line immunoassay (LIA) and digital liquid chip method (DLCM), in patients with ALD. A total of 291 serum samples were collected, consisting of 180 sera from patients with ALD and 111 sera from controls. The samples were detected through LIA and DLCM. The agreement and diagnostic performance of each assay were analyzed. There was substantial to almost perfect agreement among prevalent autoantibodies (anti-mitochondrial antibody M2, antibodies against gp210, Sp100, and Ro52). Nevertheless, the Cohen κ coefficient of some uncommon autoantibodies (anti-LKM-1, anti-LC-1, and anti-SLA/LP) between the 2 methods was not ideal. LIA showed slightly better sensitivity, accuracy, and negative predictive value, while DLCM exhibited slightly higher specificity and positive predictive value. LIA and DLCM demonstrated comparable performance for the detection of common ALD-related autoantibodies. LIA seemed to be more sensitive, while DLCM displayed more specificity. However, standardization of ALD autoantibody detection still faces challenges between these diverse detection systems. Comprehensive interlaboratory validation is essential to mitigate potential misunderstanding and confusion among patients and clinicians.

Structural Basis for Recognition of the FLAG-tag by Anti-FLAG M2

The FLAG-tag/anti-FLAG system is a widely used biochemical tool for protein detection and purification. Anti-FLAG M2 is the most popular antibody against the FLAG-tag, due to its ease of use, versatility, and availability in pure form or as bead conjugate. M2 binds N-terminal, C-terminal and internal FLAG-tags and binding is calcium-independent, but the molecular basis for the FLAG-tag specificity and recognition remains unresolved.Here we present an atomic resolution (1.17 Å) structure of the FLAG peptide in complex with the Fab of anti-FLAG M2, revealing key binding determinants. Five of the eight FLAG peptide residues form direct interactions with paratope residues. The FLAG peptide adopts a 310 helix conformation in complex with the Fab. These structural insights allowed us to rationally introduce point mutations on both the peptide and antibody side. We tested these by surface plasmon resonance, leading us to propose a shorter yet equally binding version of the FLAG-tag for the M2 antibody.

Altered placental macrophage numbers and subsets in pregnancies complicated with intrahepatic cholestasis of pregnancy (ICP) compared to healthy pregnancies

IntroductionIntrahepatic cholestasis of pregnancy (ICP) can result in adverse outcomes for both mother and fetus. Inflammatory (M1 subset) or anti-inflammatory (M2 subset) macrophage polarisation is associated with various complications of pregnancy. However, the influence of ICP on macrophage numbers and polarisation remains unknown. This study analyses macrophage density and distribution in placentas of patients with ICP compared to controls. Clinical parameters were correlated to macrophage distribution and ursodeoxycholic acid use (UDCA). MethodsThis study included routinely collected placental tissue samples of 42 women diagnosed with ICP and of 50 control pregnancies. Immunohistochemical staining was performed on placental tissue using CD68 antibody as a pan-macrophage marker, CD206 antibody as an M2 and HLA-DR antibody as an M1 macrophage marker. Macrophage density (cells/mm2) and distribution (CD206+/CD68+ or CD206+/CD68+HLA-DR+) in both decidua (maternal tissue) and villous parenchyma (fetal tissue) were compared between groups. Macrophage density and distribution were correlated to clinical parameters for ICP patients. ResultsThe density of CD68+ macrophages differed significantly between groups in villous parenchyma. In both decidua and villous parenchyma, CD206+/CD68+ ratio was significantly lower in ICP patients compared to controls (p = 0.003 and p=<0.001, respectively). No difference was found based on UDCA use or in CD68+HLA-DR+ cell density. Significant correlations were found between macrophage density and peak serum bile acids and liver enzymes. DiscussionIn ICP patients, an immune shift was observed in both decidual and villous tissue, indicated by a lower CD206+/CD68+ ratio. ICP seems to affect placental tissue, however more research is required to understand its consequences.

The A986S calcium sensing receptor variant supports the adaptation of breast cancer cells to high calcium — a novel paradigm in breast cancer progression

Breast cancer and other solid tumors that metastasize to bone are frequently accompanied by a progressive increase in circulating calcium as the disease becomes more malignant. The increase in circulating calcium not only disrupts systemic calcium homeostasis but also alters the ability of cells to sense slight changes in extracellular Ca2+ via the ubiquitous calcium sensing receptor (CaSR). Of the CASR polymorphisms at rs1801725 (p.A986S), rs1801726 (p.Q1011E), and rs1042636 (p.R990G) in exon 7 of the receptor, previous studies have shown that only the A986S CaSR variant is associated with calcium in breast, prostate and skin cancers. In this study, we assessed if exon 7 inactivating A986S (AS-CaSR) and Q1011E (QE-CaSR) variants of the receptor influence the survival of breast tumor cells at higher Ca2+. We generated isogenic HEK293T and BT-549 cells expressing these CaSR variants and carried out bulk RNA sequencing of high Ca2+ adapted control and breast cancer cells. CaSR expression was detected by western blotting using anti-flag M2 (Sigma) antibody. By using phospho-ERK1/2 as the readout, the activation of AS-CaSR required higher concentrations of Ca2+ (EC50 ~5.28 mM) compared to the QE-CaSR (EC50 of ~3.81 mM) and the wild type (WT-CaSR; EC50 ~3.69 mM) receptor. When the CaSR variants transfected cells initially cultured at 7.5 mM for 6 days, and then sub-cultured in medium containing 7.5 to 20 mM Ca2+, the viability of empty vector control and WT-CaSR transfected cells strongly decreased at Ca2+ levels beyond 7.5 mM and these cells were mostly necrotic at ≥15 mM Ca2+. The QE-CaSR variant transfected cells on the other hand exhibited limited cell death beyond 10 mM Ca2+, while the surviving colonies of the AS-CaSR variant were viable at up to 15 mM Ca2+ with invasive tendencies. Analysis of differentially expressed genes in high Ca2+ adapted mesenchymal-like BT-549 and epithelial MDA-MB-468 breast cancer cells compared to MCF10A control cells revealed a small set of differentially expressed genes that were significantly associated with relapse free survival of basal-like breast cancer patients. Among these genes are ligands and negative regulators of the WNT/FZD pathway. Our data suggest that the A986S-CaSR variant with reduced sensitivity to Ca2+ supported adaptation of TNBC cells at high Ca2+, and that high Ca2+ adaptation of breast cancer cells may be mediated via a panel of high Ca2+ inducible genes with implications in bone metastasis. This study is supported by NIH SC1GM139814, T32AI007281, T32GM144927, T32HL007737; and the American Cancer Society. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Abstract 1368: Novel mRNA encoding anti-PD-L1 monoclonal antibodies for cancer immunotherapy

Abstract The difficulties with antibody-based therapies stem from their steep costs, complex procedures, and contamination risks. We investigate the use of in vitro transcription (IVT) for mRNA production, presenting a novel approach to traditional antibody treatments by promoting internal protein or antibody synthesis. We aim to create innovative mRNA-based anti-PD-L1 antibodies with strong immunotherapeutic effectiveness. The study begins with mouse immunization and hybridoma generation. Immunizing mice with the glycosylated extracellular domain of PD-L1 produces mouse antibodies against human PD-L1. Hybridomas, derived from post-immunization splenocytes, yield monoclonal antibodies screened for PD-L1 binding affinity via flow cytometry. A neutralizing assay identifies 22 antibodies with similar IC50 values and shared binding epitopes. M1, chosen for glycospecificity, affinity, and neutralizing activity, undergoes additional evaluation for the expression and anti-tumor efficacy of mRNA-encoded antibodies. The expression of M1 and atezolizumab antibodies is facilitated through an mRNA-lipid nanoparticles (LNPs) delivery system. Following intravenous administration in mice, sustained serum levels of M1 (ranging from 100 to 700 μg/mL at 24 hours post-injection) are observed. Serum concentrations of M1 and atezolizumab antibody peak at the first timepoint (24 or 48 h) after mRNA-LNP injection, respectively, and then significantly decrease within the next 4 days, with a gradual decline over the next 2 weeks. Conversely, the serum concentrations of M1 or atezolizumab protein decline significantly 24 hours post-injection and consistently stay at a baseline level (t1/2 of 94 and 4 h for M1 mRNA-LNP and protein, respectively). This indicates that the injection of encoded mRNA in mice can stably and continuously express antibodies.Administering Atezolizumab mRNA-LNP through two intravenous injections leads to a significant decrease in MC38 tumor growth, exhibiting a dose-dependent effect (TGI% = 8.1, 43.1, and 62.8 for doses of 0.2, 0.6, and 1 mg/kg, respectively). A complete tumor regression was observed up to day 19 following injection with a 2 mg/kg dose of mRNA-LNP (TGI% = 90.8%). Remarkably, a 3 mg/kg dose of atezolizumab antibody demonstrates a similar reduction in tumor growth as 0.6 mg/kg of the mRNA-LNP formulation in this model. In conclusion, this research underscores the potential of LNP-formulated mRNA as a transformative approach, converting the human body into a site for the continuous, stable expression of antibodies, offering a promising alternative to traditional protein-based therapies for combating cancer. This innovative approach shows promise in overcoming the limitations associated with traditional antibody production and clinical utilization. Citation Format: Ezra Chung, Yong Sik Bong, Renxiang Chen, Michael Zhang, Steven Long, Dong Shen. Novel mRNA encoding anti-PD-L1 monoclonal antibodies for cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1368.

Fatty infiltration in the posterior muscles of the lower extremities as an MRI feature in antimitochondrial antibody-associated myopathy.

Idiopathic inflammatory myopathy (IIM) with antimitochondrial M2 antibody (AMA-M2) has been associated with distinct clinical characteristics. In this study, we explore the magnetic resonance imaging (MRI) findings of the muscles of the lower extremities in AMA-M2-positive IIM to gain more insight. MRI of 22 lower extremity muscles was retrospectively evaluated in 14 patients with AMA-M2-positive IIM and 37 age- and sex-matched patients with AMA-M2-negative IIM. Muscles with inflammatory edema and fatty infiltration were assessed according to the Stramare and Mercuri criteria. Patients with AMA-M2-positive IIM had significantly higher incidence of MRI involvement with fatty infiltration in five lower extremity muscles, namely the adductor magnus (AM) (13/14 VS 14/37, p < 0.001), semimembranosus (SM) (13/14 VS 17/37, p = 0.002), biceps femoris (BF) (12/14 VS 15/37, p = 0.004), soleus (13/14 VS 23/37, p = 0.041), and the medial head of the gastrocnemius (Gastroc M) (13/14 VS 17/37, p = 0.002) than patients with AMA-M2-negative IIM. Furthermore, the severity scores of fatty infiltrations of the above five muscles in AMA-M2-positive IIM were significantly higher than those in patients with AMA-M2-negative IIM (p < 0.001). Severe fatty infiltrations of the AM, SM, BF, soleus, and Gastroc M in the posterior muscles of the lower extremities are dominant MRI features in our patients with AMA-M2-positive IIM. This unique muscle MRI character may be a helpful indicator in clinical practice for patients with AMA-M2-positive IIM. Key Points • Striking involvement and prominent fatty infiltrations of five lower extremity muscles (adductor magnus, semimembranosus, biceps femoris, soleus, and the medial head of the gastrocnemius) are interesting MRI performances. • Severe fatty infiltrations in the posterior muscles of the lower extremities are dominant MRI features in AMA-M2-positive IIM. • This unique muscle MRI character may be very helpful for the diagnosis of the AMA-M2-positive IIM.

Selective Tumor Hypoxia Targeting Using M75 Antibody Conjugated Photothermally Active MoOx Nanoparticles.

Photothermal therapy (PTT) mediated at the nanoscale has a unique advantage over currently used cancer treatments, by being spatially highly specific and minimally invasive. Although PTT combats traditional tumor treatment approaches, its clinical implementation has not yet been successful. The reasons for its disadvantage include an insufficient treatment efficiency or low tumor accumulation. Here, we present a promising new PTT platform combining a recently emerged two-dimensional (2D) inorganic nanomaterial, MoOx, and a tumor hypoxia targeting element, the monoclonal antibody M75. M75 specifically binds to carbonic anhydrase IX (CAIX), a hypoxia marker associated with many solid tumors with a poor prognosis. The as-prepared nanoconjugates showed highly specific binding to cancer cells expressing CAIX while being able to produce significant photothermal yield after irradiation with near-IR wavelengths. Small aminophosphonic acid linkers were recognized to be more effective over the combination of poly(ethylene glycol) chain and biotin-avidin-biotin bridge in constructing a PTT platform with high tumor-binding efficacy. The in vitro cellular uptake of nanoconjugates was visualized by high-resolution fluorescence microscopy and label-free live cell confocal Raman microscopy. The key to effective cancer treatment may be the synergistic employment of active targeting and noninvasive, tumor-selective therapeutic approaches, such as nanoscale-mediated PTT. The use of active targeting can streamline nanoparticle delivery increasing photothermal yield and therapeutic success.

Clinical value of chemiluminescence method for detection of antinuclear antibody profiles.

Antinuclear antibodies (ANAs) are crucial in diagnosing autoimmune diseases, mainly systemic lupus erythematosus (SLE). This study aimed to compare the performance of chemiluminescence assay (CLIA) and line immunoassay (LIA) in detecting ANAs in patients with autoimmune diseases, evaluate their diagnostic accuracy for SLE, and develop a novel diagnostic model using CLIA-detected antibodies for SLE. Specimens from patients with autoimmune diseases and physical examination specimens were collected to parallel detect specific antibodies. Individual antibodies' diagnostic performance and a model combining multiple antibodies were assessed. The findings provide valuable insights into improving the diagnosis of SLE through innovative approaches. To compare the performance of CLIA and LIA in detecting ANAs in patients with autoimmune diseases, assess their accuracy for SLE, and develop a novel diagnostic model using CLIA-detected antibodies for SLE. Specimens have been obtained from 270 patients with clinically diagnosed autoimmune disorders, as well as 130 physical examination specimens. After that, parallel detection of anti-double-stranded DNA (dsDNA) antibody, anti-histone (Histone) antibody, anti-nucleosome (Nuc) antibody, anti-Smith (Sm) antibody, anti-ribosomal P protein (Rib-P) antibody, anti-sicca syndrome A (Ro60) antibody, anti-sicca syndrome A (Ro52) antibody, anti-sicca syndrome (SSB) antibody, anti-centromere protein B (Cenp-B) antibody, anti-DNA topoisomerase 1 (Scl-70) antibody, anti-histidyl tRNA synthetase (Jo-1) antibody, and anti-mitochondrial M2 (AMA-M2) antibody was performed using CLIA and LIA. The detection rates, compliance rates, and diagnostic performance for SLE were compared between the two methodologies, followed by developing a novel diagnostic model for SLE. CLIA and LIA exhibited essentially comparable detection rates for anti-dsDNA antibody, anti-Histone antibody, anti-Nuc antibody, anti-Sm antibody, anti-Rib-P antibody, anti-Ro60 antibody, anti-Ro52 antibody, anti-SSB antibody, anti-Cenp-B antibody, anti-DNAScl-70 antibody, anti-Jo-1 antibody and anti-AMA-M2 antibody (P > 0.05). The two methods displayed identical results for the detection of anti-dsDNA antibody, anti-Histone antibody, anti-Nuc antibody, anti-Sm antibody, anti-Ro60 antibody, anti-Ro52 antibody, anti-SSB antibody, anti-Cenp-B antibody, anti-Scl-70 antibody, and anti-AMA-M2 antibody (Kappa > 0.7, P < 0.05), but showed a moderate agreement for the detection of anti-Rib-P antibody and anti-Jo-1 antibody (Kappa = 0.671 and 0.665; P < 0.05). In addition, the diagnostic performance of these antibodies detected by both methods was similar for SLE. The diagnostic model's area under the curve values, sensitivity, and specificity, including an anti-dsDNA antibody and an anti-Ro60 antibody detected by CLIA, were 0.997, 0.962, and 0.978, respectively. These values were higher than the diagnostic performance of individual antibodies. CLIA and LIA demonstrated excellent overall consistency in detecting ANA profiles. A diagnostic model based on CLIA-detected antibodies can successfully contribute to developing a novel technique for detecting SLE.

OR26-01 A Novel Small Molecule Thyrotropin Receptor Antagonist

Abstract Disclosure: G.J. Kahaly: None. A. George: None. L. Steiner: None. T. Weirauch: None. J. Henseling: None. L. Frommer: None. J. Wolf: None. Background &amp; aims: Treatment of both Graves’ hyperthyroidism (GH) and Graves’ orbitopathy (GO) is still far from adequate, hence new therapeutic modalities, which specifically target the autoantigens in GH/GO, are warranted. This study determined the preclinical in vitro efficacy of SYD5115, a novel thyrotropin receptor (TSH-R) antagonist. Methods: SYD5115 is a nanomolar potent low molecular weight TSH-R antagonist with in vivo activity in rats after oral dosing. The compound consists of an N-acetylated dihydropyrrole pyrimidine core containing several substituents such as a difluorinated-spirocyclohexyl ring and a chiral carbamate group on the pyrimidine ring. The TSH-R inhibiting capability of SYD5115 was tested through stimulation of wild type and chimeric TSH-R expressed in Chinese hamster ovary (CHO) cells using-two functional (stimulatory and blocking) cell-based TSH-R-Ab bioassays. TSH-R expressing human orbital fibroblasts, collected from GH+GO patients (GOF), were stimulated with the monoclonal antibody M22 or with stimulatory TSH-R-Ab (TSAb)-positive sera with cyclic adenosine monophosphate (cAMP) or hyaluronic acid (HA) release as read-outs. The effect of SYD5115 on the viability of GOF was tested in both 4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide and the “scratch” cell growth assays. Results: The new small molecule SYD5115 significantly and dose-dependently inhibited the TSH-R activation through M22 or TSAb-positive sera in all performed bioassays. Inhibition showed similar levels in the TSAb reporter bioassay and in the cAMP assay with GOF. The % inhibition and compound concentration showed a sigmoidal relationship, with all seven TSAb positive sera markedly inhibited by SYD5115. A SYD5115 dose-dependent inhibition of M22 (10ng/ml, 6 hours)-stimulated HA and/or cAMP-release from GOF was observed. Strong SYD5115-induced inhibitions of M22-stimulated cAMP production in GOF were registered with SYD5115 concentrations of one (p=0.0029), 10 (p&amp;lt;0.0001), 100 (p&amp;lt;0.0001), 1,000 (p&amp;lt;0.0001), and 10,000 (p&amp;lt;0.0001) nM/L, respectively. SYD5115-induced inhibition of M22-stimulated HA production was noted with SYD5115 concentrations of 100 (p=0.0392), 1,000 (p=0.0431), and 10,000 (p=0.0245) nM/L, respectively. The inhibitory activity of SYD5115 was confirmed in a human osteosarcoma U2OS cell line stably expressing human TSH-R with cAMP as read-out. SYD5115 induced 100% inhibition of the M22-induced cAMP levels with a potency of 193 nM. Compared to control, SYD5115 affected neither the growth nor the migration of cultivated GOF. In addition, SYD5115 did not alter the viability of GOF. Conclusions: SYD5115 blocked M22- and TSAb-induced TSH-R activity with a nanomolar potency in TSH-R overexpressed CHO cells as well as primary GOF, which demonstrates the ability of this novel small molecule to inhibit TSH-R overactivity. Presentation: Saturday, June 17, 2023

P323 Differences in clinicopathology and therapeutic response of idiopathic inflammatory myopathy with anti-SRP, HMGCR, and mitochondrial M2 antibodies

P323 Differences in clinicopathology and therapeutic response of idiopathic inflammatory myopathy with anti-SRP, HMGCR, and mitochondrial M2 antibodies

Magnetic resonance imaging findings of the lower limb muscles in anti-mitochondrial M2 antibody-positive myositis

Anti-mitochondrial M2 antibody (AMA-M2)-positive myositis is an idiopathic inflammatory myopathy (IIM). Of all patients with myositis, 2.5–19.5% have AMA-M2 antibodies. However, the detailed distribution of muscles affected in AMA-positive myositis is unknown. Therefore, we examined lower muscle magnetic resonance imaging (MRI) findings of patients with AMA-positive myositis. Among the 63 patients with IIM at our institute, 5 (7.9%) were positive for AMA-M2 antibodies. However, one was also positive for anti-Jo1 antibodies; therefore, four patients were finally participated in this study. All patients had high-intensity MRI signals in the proximal muscles, including the gluteus maximus and iliopsoas muscles, and in the thigh muscles, including the vastus lateralis, vastus medialis, adductor magnus, and semimembranosus muscles. Lower leg muscles were relatively spared. Fascial edema was observed in all patients and was also present in the lower leg muscles. Subcutaneous edema was observed, particularly in the proximal portion of the lower limbs. In AMA-positive myositis, proximal muscles, including the gluteus maximus, vastus lateralis, adductor magnus, and the semimembranosus, were markedly affected, while the lower leg muscles were relatively preserved. Additionally, fascial edema was evident even in lower leg muscles. Therefore, muscle MRI can be a useful diagnostic aid for AMA-positive myositis.

Thyrotropin Receptor Antagonism by a Novel Small Molecule: Preclinical In Vitro Observations.

Background: Treatment of Graves' hyperthyroidism (GH) and Graves' orbitopathy (GO) is far from adequate, and hence, new substances that specifically target the autoantigens in GH/GO are warranted. This study determined the preclinical in vitro efficacy of SYD5115, a novel low-molecular-weight compound that inhibits the thyrotropin receptor (TSH-R). Methods: The TSH-R inhibiting capability of SYD5115 was tested through stimulation of wild-type and chimeric TSH-R expressed in Chinese hamster ovary (CHO) cells using two functional (stimulatory and blocking) cell-based TSH-R-Ab bioassays. TSH-R expressing human orbital fibroblasts, collected from GH+GO patients (GOF), were stimulated with the monoclonal antibody M22 or with stimulatory TSH-R-Ab (TSAb)-positive sera with cyclic adenosine monophosphate (cAMP) or hyaluronic acid (HA) release as readouts. The effect of SYD5115 on the viability of GOF was tested in 4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide and scratch cell growth assays. Results: SYD5115 significantly and dose dependently inhibited the TSH-R activation through M22 or TSAb-positive sera in all performed bioassays. Inhibition showed similar levels in the TSAb reporter bioassay and in the cAMP assay with GOF. The % inhibition and compound concentration showed a sigmoidal relationship, with all seven TSAb-positive sera markedly inhibited by SYD5115. An SYD5115 dose-dependent inhibition of M22 (10 ng/mL, 6 hours)-stimulated HA and/or cAMP-release from GOF was observed. Strong SYD5115-induced inhibitions of M22-stimulated cAMP production in GOF were registered with SYD5115 concentrations of 1 (p = 0.0029), 10 (p < 0.0001), 100 (p < 0.0001), 1,000 (p < 0.0001), and 10,000 (p < 0.0001) nM, respectively. SYD5115-induced inhibition of M22-stimulated HA production was noted with SYD5115 concentrations of 100 (p = 0.0392), 1000 (p = 0.0431), and 10,000 (p = 0.0245) nM, respectively. The inhibitory activity of SYD5115 was confirmed in a human osteosarcoma U2OS cell line stably expressing human TSH-R with cAMP as readout. SYD5115 induced 100% inhibition of the M22-induced cAMP levels with a potency of 193 nM. Compared with control, SYD5115 did neither impact the growth nor the migration of cultivated GOF. In addition, SYD5115 did not alter the viability of GOF. Conclusions: SYD5115 blocked M22- and TSAb-induced TSH-R activity with a nanomolar potency in TSH-R-overexpressed CHO cells as well as primary GOF, which demonstrates the ability of this small molecule to block TSH-R overactivity.

A population-based characterization study of anti-mitochondrial M2 antibodies and its consistency with anti-mitochondrial antibodies.

This study aims to estimate the prevalence of anti-mitochondrial antibody subtype M2 (AMA-M2) and assess its consistency with AMA in a general population. A total of 8954 volunteers were included to screen AMA-M2 using enzyme-linked immunosorbent assay. Sera with AMA-M2>50 RU/mL were further tested for AMA using an indirect immunofluorescence assay. The population frequency of AMA-M2 positivity was 9.67%, of which 48.04% were males and 51.96% were females. The AMA-M2 positivity in males had a peak and valley value of 7.81% and 16.88% in those aged 40 to 49 and ≥70years, respectively, whereas it showed a balanced age distribution in females. Transferrin and immunoglobulin M were the risk factors for AMA-M2 positivity and exercise was the only protective factor. Of 155 cases with AMA-M2>50 RU/mL, 25 cases were AMA-positive, with a female-to-male ratio of 5.25:1. Only 2 people, with very high AMA-M2 of 760 and >800 RU/mL, met the diagnostic criteria of primary biliary cholangitis (PBC), making the prevalence of PBC 223.36 per million in southern China. We found that AMA-M2 has a low coincidence rate with AMA in the general population. Anew decision-making point for AMA-M2 is needed to improve consistency with AMA and diagnostic accuracy.

Vibrio vulnificus sepsis after shrimp shelling in a patient with preexisting primary biliary cholangitis: a case report

BackgroundVibrio vulnificus is typically present in seawater, fish, and shellfish, and is known to cause severe sepsis, particularly in patients with liver diseases such as cirrhosis. V. vulnificus is one of the most dangerous waterborne pathogens, and infection mainly occurs in western Japan during the summer, with an increased fatality rate. Herein, we report the case of a patient with primary biliary cholangitis and sepsis caused by V. vulnificus infection sustained through shrimp shelling.Case presentationAn 82-year-old Japanese Asian woman with no medical history or underlying disease developed redness, swelling, and pain, which extended from the right fingers to the upper arm. A diagnosis of sepsis due to cellulitis was made. Blood culture detected V. vulnificus; thus, minocycline was administered in addition to meropenem. The disease course was uneventful, and the patient was discharged on day 28 of hospitalization. Symptoms in the right upper arm developed 1 day after the patient shelled a large number of shrimp; therefore, the infection route was assumed to be through wounds sustained during shrimp shelling. We suspected liver disease and measured serum anti-mitochondrial M2 antibody levels, leading to the diagnosis of primary biliary cholangitis.ConclusionsAs in this case, small wounds caused by handling fish and shrimp are a potential source of infection. Patients with severe V. vulnificus infection should be thoroughly assessed for the presence of liver diseases such as primary biliary cholangitis.

Comprehensive autoantibody profiles in systemic sclerosis: Clinical cluster analysis.

Systemic sclerosis (SSc) belongs to the group of connective tissue diseases and is associated with the occurrence of disease-specific autoantibodies. Although it is still controversial whether these antibodies contribute to pathogenesis, there are new insights into the development of these specific antibodies and their possible pathophysiological properties. Interestingly, they are associated with specific clinical manifestations, but for some rarer antibodies this association is not fully clarified. The aim of this study is a comprehensive analysis of the serum autoantibody status in patients with SSc followed by correlation analyses of autoantibodies with the clinical course of the disease. Serum from SSc patients was analyzed using a line blot (EUROLINE, EUROIMMUN AG) for SSc-related autoantibodies. Autoantibodies to centromere, Topo-1, antimitochondrial antibodies (AMA) M2 subunit, angiotensin II type 1 receptors (AT1R) and endothelin-1 type-A-receptors (ETAR) were also determined by ELISA. We formed immunological clusters and used principal components analysis (PCA) to assign specific clinical characteristics to these clusters. A total of 372 SSc patients were included. 95.3% of the patients were antinuclear antibody positive and in 333 patients at least one SSc specific antibody could be detected. Four immunological clusters could be found by PCA. Centromere, Topo-1 and RP3 all formed own clusters, which are associated with distinct clinical phenotypes. We found that patients with an inverted phenotype, such as limited cutaneous SSc patients within the Topo-1 cluster show an increased risk for interstital lung disease compared to ACA positive patients. Anti-AT1R and anti-ETAR autoantibodies were measured in 176 SSc patients; no association with SSc disease manifestation was found. SSc patients with AMA-M2 antibodies showed an increased risk of cardiovascular events. In our in large cluster analysis, which included an extended autoantibody profile, we were able to show that serologic status of SSc patients provides important clues to disease manifestation, co-morbidities and complications. Line blot was a reliable technique to detect autoantibodies in SSc and detected rarer autoantibodies in 42% of our patients.

S2963 Congenital Riedel’s Lobe of the Liver: A Case Report

Introduction: Riedel lobe of the liver is a rare anatomical variation with a reported incidence to be between 3.3% and 14.5%. We report a case of a 43-year-old female with an incidental finding of non-palpable Riedel’s lobe. Case Description/Methods: A 43-year-old female was referred for evaluation of hepatomegaly, which was revealed on MRI and CT scan dating back to 2016. Medical history notable for Irritable Bowel Syndrome (IBS), uterine fibroids, and a history of a tumor removal from her right breast. Patient denies any history of alcohol, illicit drugs, hepatotoxic medications, or pre-existing liver disease. Physical exam was unremarkable and abdominal exam did not reveal any mass or abnormalities. Routine blood examination, including LFTs and iron studies, was within normal limits. Hepatitis panel (A, B, C), anti-smooth muscle antibody, and LKM-1 IgG antibody was negative. ANA, alpha-1 antitrypsin, and tissue transglutaminase were all negative. The only lab abnormality was an elevated IgG mitochondrial M2 antibody 54.5 (normal less than 20 units). CT abdomen was significant for an enlarged liver with the right lobe extending into the pelvis and ‘not completely included in the study’. MRI abdomen revealed a markedly enlarged liver measuring up to 23.8cm in its craniocaudal dimension with extension into the pelvis with the pancreas deviated to the left, likely secondary to the prominent hepatomegaly. Venous duplex significant for normal directional flow in the portal and hepatic veins with no evidence of portal hypertension. Liver biopsy revealed signs of sinusoidal dilatation nonspecific for veno-occlusive outflow obstruction with no signs of inflammation, steatosis, or fibrosis. The patient was diagnosed with Riedel’s lobe of the liver. She was discharged from the hospital without treatment with a recommendation to repeat an MRI in 1 year, as torsion is a reported complication of Riedel’s lobe over time. Patient will be recommended to repeat LFTs and anti-mitochondrial antibody to determine progression/significance prior to follow up in 6 months. Discussion: Riedel’s lobe of the liver is a rare anatomical variant that is often incidentally found on imaging or the presence of hepatomegaly on physical exam. Although patients are usually asymptomatic, its presentation can vary, ranging from nonspecific symptoms to more severe symptoms such as torsion, obstruction, rupture, and bleeding. The range of symptoms highlights its importance in diagnosis and surveillance in this patient population.Figure 1.: (A) CT of the abdomen/pelvis from 2016. Liver measuring up to 197.3mm in the sagittal plane. (B) CT of the abdomen/pelvis from 2020. Liver measuring up to 215.4mm in the sagittal plane.

Expression of Helper T Cell Type 17 and CD4+ CD25+ Tregs in AMA-M2 Positive PBC Patients

Objective: To investigate the expression and impact of helper T cell type 17 and CD4+ CD25+ regulatory T (Treg) cells in anti-mitochondrial M2 antibody (AMA-M2) positive primary biliary cholangitis (PBC) patients. Methods: Thirty PBC patients with positive AMA (M2 type) (antibody titer above 1:320) by indirect immunofluorescence assay under the Affiliated Hospital of Hebei University from November 2021 to August 2022 were selected as the experimental group, while 30 healthy individuals were selected as controls. The subjects were observed and analyzed for AFP-L3 and immunoglobulin expression. Results: The levels of Thl7, Treg, Thl7/Treg, interleukin (IL)-17A, IL-2, IL-10, and transforming growth factor (TGF)-?1 cytokines of the experimental group were 2.61 ± 0.48, 1.15 ± 0.54, 2.41 ± 0.47, 310.94 ± 21.14, 276.36 ± 36.12, 317.89 ± 28.97, and 197.48 ± 31.04, respectively, while those of the control group were 1.14 ± 0.58, 0.88 ± 0.29, 1.47 ± 0.25, 9.69 ± 1.26, 57.69 ± 2.45, 154.01 ± 19.87, and 514.36 ± 36.12, respectively, wherein P &lt; 0.05; the CD4+, CD8+, and CD4+/CD8+ of the experimental group were 39.48 ± 4.19, 20.12 ± 4.41, and 1.76 ± 0.14, respectively, while those of the control group were 35.78 ± 4.21, 22.01 ± 4.16, and 1.51 ± 0.13, respectively, wherein P &lt; 0.05. Conclusion: In patients with PBC, there is a significant imbalance in Thl7/Treg cells. Il-17A, IL-2, IL-10, and TGF- ?1 cytokines play important roles in the differentiation and functional expression of both Thl7 and Treg cells.