Pim-2/mTORC1 Pathway Shapes Inflammatory Capacity in Rheumatoid Arthritis Synovial Cells Exposed to Lipid Peroxidations

PIM Kinases as Potential Biomarkers and Therapeutic Targets in Inflammatory Arthritides

The Proviral Integration site for the Moloney murine leukemia virus (PIM)-1 kinase and its family members (PIM-2 and PIM-3) regulate several cellular functions including survival, proliferation, and apoptosis. Recent studies showed their involvement in the pathogenesis of rheumatoid arthritis RA, while no studies are available on psoriatic arthritis (PsA) and axial spondyloarthritis (axSpA). The main objective of this study is to assess the expression of PIM kinases in inflammatory arthritides, their correlation with proinflammatory cytokines, and their variation after treatment with biologic disease-modifying anti-rheumatic drugs or JAK inhibitors. We evaluated PIM-1, -2, and -3 expression at the gene and protein level, respectively, in the peripheral blood mononuclear cells and serum of patients with RA, PsA, axSpA, and healthy individuals (CTR). All the samples showed expression of PIM-1, -2, and -3 kinases both at the gene and protein level. PIM-1 was the most expressed protein, PIM-3 the least. PIM kinase levels differed between controls and disease groups, with reduced PIM-1 protein and increased PIM-3 protein in all disease samples compared to controls. No difference was found in the expression of these molecules between the three different pathologies. PIM levels were not modified after 6 months of therapy. In conclusion, our preliminary data suggest a deregulation of the PIM pathway in inflammatory arthritides. In-depth studies on the role of PIM kinases in this field are warranted.

Protective effects of cell permeable Tat-PIM2 protein on oxidative stress induced dopaminergic neuronal cell death

Background

Oxidative stress is considered as one of the main causes of Parkinson's disease (PD), however the exact etiology of PD is still unknown. Although it is known that Proviral Integration Moloney-2 (PIM2) promotes cell survival by its ability to inhibit formation of reactive oxygen species (ROS) in the brain, the precise functional role of PIM2 in PD has not been fully studied yet.

Objective

We investigated the protective effect of PIM2 against apoptosis of dopaminergic neuronal cells caused by oxidative stress-induced ROS damage by using the cell permeable Tat-PIM2 fusion protein in vitro and in vivo.

Methods

Transduction of Tat-PIM2 into SH-SY5Y cells and apoptotic signaling pathways were determined by Western blot analysis. Intracellular ROS production and DNA damage was confirmed by DCF-DA and TUNEL staining. Cell viability was determined by MTT assay. PD animal model was induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and protective effects were examined using immunohistochemistry.

Results

Transduced Tat-PIM2 inhibited the apoptotic caspase signaling and reduced the production of ROS induced by 1-methyl-4-phenylpyridinium (MPP⁺) in SH-SY5Y cells. Furthermore, we confirmed that Tat-PIM2 transduced into the substantia nigra (SN) region through the blood-brain barrier and this protein protected the Tyrosine hydroxylase-positive cells by observation of immunohistostaining. Tat-PIM2 also regulated antioxidant biomolecules such as SOD1, catalase, 4-HNE, and 8-OHdG which reduce the formation of ROS in the MPTP-induced PD mouse model.

Conclusion

These results indicated that Tat-PIM2 markedly inhibited the loss of dopaminergic neurons by reducing ROS damage, suggesting that Tat-PIM2 might be a suitable therapeutic agent for PD.

Pim-2 kinase inhibits inflammation by suppressing the mTORC1 pathway in atherosclerosis

Background: Inflammatory immunity theory has raised considerable concern in the pathogenesis of atherosclerosis. Proviral integration site of murine 2 (Pim-2) kinases functions in apoptosis pathways and the anti-inflammatory response. Here, we investigated whether Pim-2 kinase inhibits atherosclerotic inflammation by suppressing the mTORC1 pathway.

Methods: An atherosclerosis animal model was established by feeding ApoE ^-/- mice a high-fat diet. THP-1-derived macrophages were subjected to ox-LDL (50 μg/ml, 24h) conditions in vitro to mimic the in vivo conditions.

Result: The protein expression of Pim-2 was upregulated in ox-LDL-treated THP-1-derived macrophages and an atherosclerotic mouse model. Additionally, ox-LDL upregulated the protein expression of p-mTOR, p-S6K1 and p-4EBP1, intracellular lipid droplets, free cholesterol and cholesterylester and the mRNA expression of inflammatory cytokines, including IL-6, MCP-1, TLR-4 and TNF-α, in THP-1-derived macrophages. Functionally, overexpressed Pim-2 (Pim-2 OE) attenuated atherosclerotic inflammation associated with the mTORC1 signaling pathway in vitro and in vivo, whereas knocked down Pim-2 (Pim-2 KD) markedly promoted atherosclerotic inflammation associated with upregulation of the mTORC1 signaling pathway. The plaque areas and lesions in the whole aorta and aortic root sections were alleviated in ApoE ^-/- mice with Pim-2 OE, but aggravated by Pim-2 KD. Additionally, an mTOR agonist (MHY1485) counteracted the anti-inflammatory effect of Pim-2 in ox-LDL-treated THP-1-derived macrophages after Pim-2 OE, whereas rapamycin rescued atherosclerotic inflammation in ox-LDL-treated THP-1-derived macrophages after Pim-2 KD. Furthermore, si-mTOR and si-Raptor alleviated the atherosclerotic proinflammatory effect in ox-LDL-treated THP-1-derived macrophages in a the background of Pim-2 KD.

Conclusions:These results indicated that Pim-2 kinase inhibits atherosclerotic inflammation by suppressing the mTORC1 pathway.

Inhibition of NF-κB signaling pathway induces apoptosis and suppresses proliferation and angiogenesis of human fibroblast-like synovial cells in rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is the most common inflammatory arthritis and is a major cause of disability. The nuclear factor-kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway has been reported to be involved in the pathogenesis of RA with unclear mechanisms. Therefore, this study aims to explore the effect of NF-κB pathway on proliferation, apoptosis, and angiogenesis of human fibroblast-like synovial cells (HFLS) in RA.

METHODS

Normal HFLS and RA-HFLS were selected as the normal and control groups, respectively. RA-HFLS were treated by BAY11-7082 (an inhibitor of NF-κB) in different concentrations, namely 2.5 μmol/L BAY11-7082, 5 μmol/LBAY11-7082 and 10 μmol/L BAY11-7082. MTT assay was employed to detect cell proliferation. Cell apoptosis was determined by flow cytometry at 24, 48, and 72 hours after culture. Western blot analysis was employed to detect the expressions of NF-κB, angiogenesis-related factors (VEGF, Ang1, and Ang2).

RESULTS

Initially, we found that BAY11-7082 inhibited NF-κB expression in a concentration-dependent manner. According to the findings of MTT assay and flow cytometry, we understood that RA-HFLS treated by BAY11-7082 (an inhibitor of NF-κB), the inhibition of NF-κB pathway, suppressed RA-HFLS proliferation and induced RA-HFLS apoptosis in a concentration and time-dependent manner. Furthermore, RA-HFLS treated by BAY11-7082 presented decreased VEGF, Ang1 and Ang2 expressions in a concentration-dependent manner.

CONCLUSION

The study concluded that inhibition of NF-κB pathway induced cell apoptosis and suppressed proliferation and angiogenesis of RA-HFLS, which could serve as a novel target in the treatment of RA.

Role of PIM2 in allergic asthma

T cell-associated inflammation, particularly type 2 inflammation, has an important role in asthma pathogenesis, which is suppressed by regulatory T cells (Tregs). Proviral integration site for Moloney murine leukemia virus 2 (PIM2), a member off the serine/threonine kinase family, promotes the growth and survival of T cells and influences the function of Treg cells. However, whether PIM2 affects asthma pathogenesis remains unclear. Peripheral blood mononuclear cells and Treg cells from asthmatic and healthy subjects were obtained, and the expression level of PIM2 was measured by reverse transcription-quantitative polymerase chain reaction and immunocytochemistry. In addition, BALB/c female mice sensitized and challenged by ovalbumin were used as an asthma model, and PIM2 inhibitor was injected during the challenge period to observe the effect of PIM2 on asthma. The asthma symptoms were recorded, and airway hyper-responsiveness (AHR), expression levels of cytokines in the serum or bronchoalveolar lavage fluid (BALF), and the number of BALF leukocytes were evaluated. In addition, hematoxylin and eosin staining and immunohistochemistry of lung tissues was performed. The results demonstrated that PIM2 was overexpressed in patients with asthma in natural Treg cells. Inhibition of PIM2 attenuated asthma symptoms, and improved AHR and airway inflammation compared with asthmatic mice without inhibition of PIM2. In addition, expression levels of interleukin (IL)-10 and forkhead box protein 3 (FOXP3) in BALF were increased following PIM2 inhibition (IL-10, 470.3±21.78 vs. 533.7±25.55 pg/ml, P<0.05; FOXP3, 259±4.68 vs. 279.3±3.68 pg/ml; asthma and PIM2 inhibition groups, respectively; P<0.05). In conclusion, PIM2 may exhibit an important role in asthma pathogenesis and exacerbate AHR, airway inflammation and asthma symptoms. These effects of PIM2 may be dependent on Treg cells and the secretion of IL-10 by Tregs. The results of the present study suggest that PIM2 may be a potential target molecule for asthma treatment.

DEPTOR-mTOR Signaling Is Critical for Lipid Metabolism and Inflammation Homeostasis of Lymphocytes in Human PBMC Culture

Abnormal immune response of the body against substances and tissues causes autoimmune diseases, such as polymyositis, dermatomyositis, and rheumatoid arthritis. Irregular lipid metabolism and inflammation may be a significant cause of autoimmune diseases. Although much progress has been made, mechanisms of initiation and proceeding of metabolic and inflammatory regulation in autoimmune disease have not been well-defined. And novel markers for the detection and therapy of autoimmune disease are urgent. mTOR signaling is a central regulator of extracellular metabolic and inflammatory processes, while DEP domain-containing mTOR-interacting protein (DEPTOR) is a natural inhibitor of mTOR. Here, we report that overexpression of DEPTOR reduces mTORC1 activity in lymphocytes of human peripheral blood mononuclear cells (PBMCs). Combination of DEPTOR overexpression and mTORC2/AKT inhibitors effectively inhibits lipogenesis and inflammation in lymphocytes of PBMC culture. Moreover, DEPTOR knockdown activates mTORC1 and increases lipogenesis and inflammations. Our findings provide a deep insight into the relationship between lipid metabolism and inflammations via DEPTOR-mTOR pathway and imply that DEPTOR-mTOR in lymphocytes of PBMC culture has the potential to be as biomarkers for the detection and therapies of autoimmune diseases.

Identification of Palmitoleic Acid Controlled by mTOR Signaling as a Biomarker of Polymyositis

Polymyositis (PM) is a chronic disease characterized by muscle pain, weakness, and increase in muscle-related enzymes, accompanied with inflammations in lymphocytes. However, it is not well understood how the molecular alternations in lymphocytes contribute to the development of polymyositis. The mechanistic target of rapamycin (mTOR) signaling is the central regulator of metabolism and inflammation in mammalian cells. Based on previous studies, we proposed that mTOR signaling may control inflammatory reactions via lipid metabolism. In this study, we aim to figure out the role of mTOR signaling in the development of polymyositis and identify novel biomarkers for the detection and therapy of polymyositis. After screening and validation, we found that palmitoleic acid, a monounsaturated fatty acid, is highly regulated by mTOR signaling. Inhibition of mTORC1 activity decreases palmitoleic acid level. Moreover, mTORC1 regulates the level of palmitoleic acid by controlling its de novo synthesis. Importantly, increased palmitoleic acid has been proven to be a marker of polymyositis. Our work identifies palmitoleic acid in peripheral blood mononuclear cells (PBMC) as a biomarker of polymyositis and offers new targets to the clinical therapy.