Research focus: Immunology and Rheumatology, Immune metabolism
Honors & Awards
Yeungnam University Foreign Student scholarship, Yeungnam University (2016)
Tribhuvan University scholarship for graduate student, Tribhuvan University (2010)
Tribhuvan University student fellowship, Tribhuvan University (2008)
Doctor of Philosophy, Yeungnam University (2021)
BS, Tribhuvan University, Microbiology (2010)
MS, Tribhuvan University, Medical Microbiology (2013)
William Robinson, Postdoctoral Faculty Sponsor
William Robinson, Postdoctoral Research Mentor
- AMPK promotes antitumor immunity by downregulating PD-1 in regulatory T cells via the HMGCR/p38 signaling pathway Molecular cancer 2021
Mevalonate promotes differentiation of regulatory T cells
JOURNAL OF MOLECULAR MEDICINE-JMM
2019; 97 (7): 927–36
Mevalonate is a precursor in a biosynthetic pathway that is important for the coordination of regulatory T cell (Treg) proliferation and upregulation of the suppressive function that establishes the functional competency of Tregs. The extensive role of mevalonate and its underlying effect on Treg differentiation are still unclear. We found that mevalonate increases in vitro differentiation of induced Tregs (iTregs) without broadly affecting Th1 and Th17 cell differentiation. Furthermore, an adoptive transfer study showed that mevalonate enhanced peripherally induced Treg cells (pTregs) in mesenteric lymphocytes in vivo. Mevalonate-treated iTregs exhibited greater suppressive activity against effector cells than untreated Tregs. Mechanistically, mevalonate enhanced transforming growth factor (TGF)-β signaling by increasing the phosphorylation of Smad3, but not Smad2, and by promoting Foxp3 expression. Furthermore, we demonstrated that mevalonate treatment ameliorated dextran sulfate sodium (DSS)-induced colitis and resulted in an increased percentage of Tregs in vivo. Our results suggest that mevalonate enhanced Treg differentiation and ameliorated DSS colitis, indicating its potential for treatment of inflammatory diseases.
View details for DOI 10.1007/s00109-019-01784-y
View details for Web of Science ID 000472081600004
View details for PubMedID 31020340
Activation of Mevalonate Pathway via LKB1 Is Essential for Stability of T-reg Cells
2019; 27 (10): 2948-+
The function of regulatory T (Treg) cells depends on lipid oxidation. However, the molecular mechanism by which Treg cells maintain lipid metabolism after activation remains elusive. Liver kinase B1 (LKB1) acts as a coordinator by linking cellular metabolism to substrate AMP-activated protein kinase (AMPK). We show that deletion of LKB1 in Treg cells exhibited reduced suppressive activity and developed fatal autoimmune inflammation. Mechanistically, LKB1 induced activation of the mevalonate pathway by upregulating mevalonate genes, which was essential for Treg cell functional competency and stability by inducing Treg cell proliferation and suppressing interferon-gamma and interleukin-17A expression independently of AMPK. Furthermore, LKB1 was found to regulate intracellular cholesterol homeostasis and to promote the mevalonate pathway. In agreement, mevalonate and its metabolite geranylgeranyl pyrophosphate inhibited conversion of Treg cells and enhanced survival of LKB1-deficient Treg mice. Thus, LKB1 is a key regulator of lipid metabolism in Treg cells, involved in optimal programming of suppressive activity, immune homeostasis, and tolerance.
View details for DOI 10.1016/j.celrep.2019.05.020
View details for Web of Science ID 000470098200014
View details for PubMedID 31167140
Amelioration of Experimental autoimmune encephalomyelitis and DSS induced colitis by NTG-A-009 through the inhibition of Th1 and Th17 cells differentiation
2018; 8: 7799
CD4+ T cells are the central for the mammalian adaptive immune system. Naïve CD4+ T cells mainly differentiate in to pro-inflammatory Th1, Th2 and Th17 cells upon antigenic stimulation. IFN-γ secreting Th1 cells and IL-17 secreting Th17 cells are found to play key roles in autoimmune diseases like multiple sclerosis (MS) and ulcerative colitis (UC). In this study we found NTG-A-009, 6-aminopyridin-3-ol, has great inhibitory effect on in vitro differentiation of Th1 and Th17 cells without affecting regulatory T cells. Moreover, NTG-A-009 had no effect on CD4+ T cell proliferation and viability. In vivo treatment has shown that NTG-A-009 has ameliorated experimental autoimmune encephalomyelitis (EAE) and dextran sulfate sodium (DSS) induced colitis through the inhibition of Th1 and Th17 cells differentiation. Mechanistically, NTG-A-009 suppressed Th1 and Th17 cells differentiation via the modulation of JAK/STAT signaling pathway. Thus, our data demonstrated that NTG-A-009 ameliorated inflammation through the inhibition of Th1 and Th17 cells generation making it a potential therapeutic candidate for the treatment of inflammatory diseases.
View details for DOI 10.1038/s41598-018-26088-y
View details for Web of Science ID 000432340600010
View details for PubMedID 29773813
View details for PubMedCentralID PMC5958108
Geranylgeranyl pyrophosphate amplifies Treg differentiation via increased IL-2 expression to ameliorate DSS-induced colitis.
European journal of immunology
Blocking the mevalonate pathway for cholesterol reduction by using statin may have adverse effects including statin-induced colitis. Moreover, one of the predisposing factors for colitis is an imbalanced CD4+ T cell, which can be observed on the complete deletion of HMG-CoA reductase (HMGCR), a target of statins. In this study, we inquired geranylgeranyl pyrophosphate (GGPP) is responsible for maintaining the T-cell homeostasis. Following dextran sulfate sodium (DSS)-induced colitis, simvastatin increased the severity of disease, while cotreatment with GGPP, but not with cholesterol, reversed the disease magnitude. GGPP ameliorated DSS-induced colitis by increasing Treg cells. GGPP amplified Treg differentiation through increased IL-2/STAT 5 signaling. GGPP prenylated Ras protein, a prerequisite for extracellular signal-regulated kinase (ERK) pathway activation, leading to increased IL-2 production. Higher simvastatin dose increased the severity of colitis. GGPP ameliorated simvastatin-increased colitis by increasing Treg cells. Treg cells, which have the capacity to suppress inflammatory T cells and were generated through IL-2/STAT5 signaling, increased IL-2 production through prenylation and activation of the Ras/ERK pathway.
View details for DOI 10.1002/eji.202048991
View details for PubMedID 33548071
Heterospheroid formation improves therapeutic efficacy of mesenchymal stem cells in murine colitis through immunomodulation and epithelial regeneration.
2021; 271: 120752
Tissue repairing capacity and immunomodulatory effects of mesenchymal stem cells (MSCs) have been extensively utilized for treating various inflammatory disorders; however, inconsistent efficacy and therapeutic outcomes due to low survival rate after transplantation often restrain their clinical potential. To overcome these limitations, 3-dimensional culture (3D-culture) was established to augment stemness and paracrine functions of MSCs, although hypoxic stress at the core often leads to unexpected cell death. Thus, we designed a novel strategy to improve the microenvironment of MSCs by creating heterospheroids (HS) consisting of MSCs and quercetin (QUR)-loaded microspheres (MSCHS), to achieve local drug delivery to the cells. Notably, MSCHS exhibited resistance for senescence-associated phenotype and oxidative stress-induced apoptosis compared to 3D-cultured MSCs (MSC3D), as well as to 2D-cultured cells (MSC2D) in vitro. In a murine model of colitis, MSC3D and MSCHS exhibited enhanced anti-inflammatory impact than MSC2Dvia attenuating neutrophil infiltration and regulating helper T cell (Th) polarization into Th1 and Th17 cells. Interestingly, MSCHS provided better therapeutic outcomes compared to MSC3D, partially due to their enhanced survival capacity in vivo. Moreover, we found that MSC-derived paracrine factor, prostaglandin E2 (PGE2), can directly drive the epithelial regeneration process by inducing specialized tissue-repairing cell generation using the intestinal organoid culture. Importantly, MSC3D and MSCHS displayed an outstanding regeneration-inducing potency compared to MSC2D owing to their superior PGE2 secretion. Taken together, we suggest a convergent strategy of MSCHS formation with reactive oxygen species (ROS) scavenger, QUR, which can maximize the inflammation-attenuating and tissue-repairing capacity of MSCs, as well as the engraftment efficiency after transplantation.
View details for DOI 10.1016/j.biomaterials.2021.120752
View details for PubMedID 33730631
Particulate-Based Single-Dose Local Immunosuppressive Regimen for Inducing Tolerogenic Dendritic Cells in Xenogeneic Islet Transplantation.
Advanced healthcare materials
Recent studies emphasize on developing immune tolerance by an interim administration of various immunosuppressive drugs. In this study, a robust protocol is reported for local immunomodulation using a single-dose of FK506 microspheres and clodronate liposomes (mFK+CLO) in a xenogeneic model of islet transplantation. Surprisingly, the single-dose treatment with mFK+CLO induce tolerance to the islet xenograft. The recipient mice display tolerogenic dendritic cells (tDCs) with decreased antigen presenting ability and T cell activation capacity. Furthermore, a reduced percentage of CD4+ and CD8+ T cells and an impaired differentiation of naive CD4+ T cells into interferon-gamma producing Th1 and interleukin-17 producing Th17 cells are observed. In addition, the immunosuppressive protocol leads to the generation of Foxp3+ regulatory T cells (Tregs) which are required for the long-term graft survival. The enhanced generation of tDCs and Tregs by the single treatment of mFK+CLO cause xenograft tolerance, suggesting a possible clinical strategy which may pave the way towards improving therapeutic outcomes of clinical islet transplantation.
View details for DOI 10.1002/adhm.202001157
View details for PubMedID 33251762
Reprogramming the T cell response to cancer by simultaneous, nanoparticle-mediated PD-L1 inhibition and immunogenic cell death
JOURNAL OF CONTROLLED RELEASE
2019; 315: 126–38
In this study, dual drug-loaded nanoparticles were constructed to co-deliver low-dose doxorubicin (DOX) and miR-200c (DOX/miR-NPs) to inhibit programmed death-1 receptor (PD-L1) expression and trigger immunogenic cell death (ICD) in cancer cells. Two block copolymers, folic acid (FA)-conjugated PLGA-PEG (PLGA-PEG-FA) and PLGA-PEI, were formulated as folate-targeted NPs and loaded with DOX and miR-200c. The NPs, which were formed as nanosize objects (110.4 ± 2.1) with narrow size distribution (0.19 ± 0.02), effectively protected the miR-200c from degradation in serum. Modifying the NPs with FA increased not only their uptake by cancer cells in vitro but also their accumulation in tumor microenvironments in vivo, as compared with those properties of non-FA-modified NPs. The DOX/miR-NPs also exhibited efficacious inhibition of PD-L1 expression and robust induction of ICD in cancer cells in vitro and in vivo, resulting in increased dendritic cell maturation and CD8+ T cell response towards cancer cells. Furthermore, tumor growth was significantly inhibited by folate-targeted NPs loaded with the low-dose DOX/miR-200c combination, but not by treatments with free DOX, miR-NPs or DOX-NPs. Thus, our results suggest that simultaneous PD-L1 inhibition via microRNAs and the induction of an immunogenic tumor microenvironment via low-dose cytotoxic drugs may improve cancer therapy efficacy.
View details for DOI 10.1016/j.jconrel.2019.10.047
View details for Web of Science ID 000500710700011
View details for PubMedID 31672625