ORM Elevation in Response to Cognitive Impairment Is an Accompanying Phenomenon

Orosomucoid 2 as a biomarker of carotid artery atherosclerosis plaque vulnerability through its generation of reactive oxygen species and lipid accumulation in vascular smooth muscle cells

BACKGROUND

Orosomucoid (ORM) has been reported as a biomarker of carotid atherosclerosis, but the role of ORM 2, a subtype of ORM, in carotid atherosclerotic plaque formation and the underlying mechanism have not been established.

METHODS

Plasma was collected from patients with carotid artery stenosis (CAS) and healthy participants and assessed using mass spectrometry coupled with isobaric tags for relative and absolute quantification (iTRAQ) technology to identify differentially expressed proteins. The key proteins and related pathways were identified via western blotting, immunohistochemistry, and polymerase chain reaction of carotid artery plaque tissues and in vitro experiments involving vascular smooth muscle cells (VSMCs).

RESULTS

We screened 33 differentially expressed proteins out of 535 proteins in the plasma. Seventeen proteins showed increased expressions in the CAS groups relative to the healthy groups, while 16 proteins showed decreased expressions during iTRAQ and bioinformatic analysis. The reactive oxygen species metabolic process was the most common enrichment pathway identified by Gene Ontology analysis, while ORM2, PRDX2, GPX3, HP, HBB, ANXA5, PFN1, CFL1, and S100A11 were key proteins identified by STRING and MCODE analysis. ORM2 showed increased expression in patients with CAS plaques, and ORM2 was accumulated in smooth muscle cells. Oleic acid increased the lipid accumulation and ORM2 and PRDX6 expressions in the VSMCs. The recombinant-ORM2 also increased the lipid accumulation and reactive oxygen species (ROS) in the VSMCs. The expressions of ORM2 and PRDX-6 were correlated, and MJ33 (an inhibitor of PRDX6-PLA2) decreased ROS production and lipid accumulation in VSMCs.

CONCLUSION

ORM2 may be a biomarker for CAS; it induced lipid accumulation and ROS production in VSMCs during atherosclerosis plaque formation. However, the relationships between ORM2 and PRDX-6 underlying lipid accumulation-induced plaque vulnerability require further research.

Into the Labyrinth of the Lipocalin α1-Acid Glycoprotein

α₁-acid glycoprotein (AGP), also known as Orosomucoid (ORM), belongs to the Lipocalin protein family and it is well-known for being a positive acute-phase protein. AGP is mostly found in plasma, with the liver as main contributor, but it is also expressed in other tissues such as the brain or the adipose tissue. Despite the vast literature on AGP, the physiological functions of the protein remain to be elucidated. A large number of activities mostly related to protection and immune system modulation have been described. Recently created AGP-knockout models have suggested novel physiological roles of AGP, including regulation of metabolism. AGP has an outstanding ability to efficiently bind endogenous and exogenous small molecules that together with the complex and variable glycosylation patterns, determine AGP functions. This review summarizes and discusses the recent findings on AGP structure (including glycans), ligand-binding ability, regulation, and physiological functions of AGP. Moreover, this review explores possible molecular and functional connections between AGP and other members of the Lipocalin protein family.

Downregulation of orosomucoid 2 acts as a prognostic factor associated with cancer-promoting pathways in liver cancer

BACKGROUND

Liver cancer has a high mortality and morbidity rate throughout the world. In clinical practice, the prognosis of liver cancer patients is poor, and the complex reasons contribute to treatment failures, including fibrosis, hepatitis viral infection, drug resistance and metastasis. Thus, screening novel prognostic biomarkers is of great importance for guiding liver cancer therapy. Orosomucoid genes (ORMs) encode acute phase plasma proteins, including orosomucoid 1 (ORM1) and ORM2. Previous studies showed their upregulation upon inflammation, but the specific function of ORMs has not yet been determined, especially in the development of liver cancer.

AIM

To determine the expression of ORMs and their potential function in liver cancer.

METHODS

Analysis of the expression of ORMs in different human tissues was performed on data from the HPA RNA-seq normal tissues project. The expression ratio of ORMs was determined using the HCCDB database, including the ratio between liver cancer and other cancers, normal liver and other normal tissues, liver cancer and adjacent normal liver tissues. Analysis of ORM expression in different cancer types was performed using The Cancer Genome Atlas and TIMER database. The expression of ORMs in liver tumor tissues and adjacent normal tissues were further confirmed using Gene Expression Omnibus data, including GSE36376 and GSE14520. The 10-year overall survival (OS), progression-free survival (PFS) and relapse-free survival (RFS) rates between high and low ORM expression groups in liver cancer patients were determined using the Kaplan-Meier plotter tool. Gene Set Enrichment Analysis (GSEA) was employed to explore the ORM2-associated signaling network. Correlations between ORM2 expression and tumor purity or the infiltration level of macrophages in liver tumor tissues were determined using the TIMER database. The correlation between ORM2 gene levels, tumor-associated macrophage (TAM) markers (including CD68 and TGFβ1) and T cell immunosuppression (including CTLA4 and PD-1) in liver tumor tissues and liver GTEx was determined using the GEPIA database.

RESULTS

ORM1 and ORM2 were highly expressed in normal liver and liver tumor tissues. ORM1 and ORM2 expression was significantly decreased in liver tumor tissues compared with adjacent normal tissues, and similar results were also noted in cholangiocarcinoma, esophageal carcinoma, and lung squamous cell carcinoma. Further analysis of the Gene Expression Omnibus Database also confirmed the downregulation of ORM1 and ORM2 in liver tumors. Survival analysis showed that the high ORM2 group had better survival rates in OS, PFS and RFS. ORM1 only represented better performance in PFS, but not in OS or RFS. GSEA analysis of ORM2 from The Cancer Genome Atlas liver cancer data identified that ORM2 positively associated with the G2/M checkpoint, E2F target signaling, as well as Wnt/β-catenin and Hedgehog signaling. Moreover, apoptosis, IFN-α responses, IFN-γ responses and humoral immune responses were upregulated in the ORM2 high group. ORM2 expression was negatively correlated with the macrophage infiltration level, CD68, TGFβ1, CTLA4 and PD-1 levels.

CONCLUSION

The results showed that ORM1 and ORM2 were highly expressed specifically in liver tissues, whereas ORM1 and ORM2 were downregulated in liver tumor tissues. ORM2 is a better prognostic factor for liver cancer. Furthermore, ORM2 is closely associated with cancer-promoting pathways.

Role of acute-phase protein ORM in a mice model of ischemic stroke

The only Food and Drug Administration-approved treatment for acute ischemic stroke is tissue plasminogen activator, and the discovery of novel therapeutic targets is critical. Here, we found orosomucoid (ORM), an acute-phase protein mainly produced by the liver, might act as a treatment candidate for an ischemic stroke. The results showed that ORM2 is the dominant subtype in mice normal brain tissue. After middle cerebral artery occlusion (MCAO), the level of ORM2 is significantly increased in the ischemic penumbra compared with the contralateral normal brain tissue, whereas ORM1 knockout did not affect the infarct size. Exogenous ORM could significantly decrease infarct size and neurological deficit score. Inspiringly, the best administration time point was at 4.5 and 6 hr after MCAO. ORM could markedly decrease the Evans blue extravasation, and improve blood-brain barrier-associated proteins expression in the ischemic penumbra of MACO mice and oxygen-glucose deprivation (OGD)-treated bEnd3 cells. Meanwhile, ORM could significantly alleviate inflammation by inhibiting the production of interleukin 1β (IL-1β), IL-6, and tumor necrosis factor α (TNF-α), reduce oxidative stress by improving the balance of malondialdehyde (MDA) and superoxide dismutase (SOD), inhibit apoptosis by decreasing caspase-3 activity in ischemic penumbra of MCAO mice and OGD-treated bEnd.3 cells. Because of its protective role at multiple levels, ORM might be a promising therapeutic target for ischemic stroke.