Joonbeom Bae

IL-10 inhibits the starvation induced autophagy in macrophages via class I phosphatidylinositol 3-kinase (PI3K) pathway.

Autophagy is an important process which maintains cellular homeostasis under stressful conditions such as starvation and pathogenic invasion. Previous observations have indicated that several cytokines are important regulators of the autophagic process. Among the various cytokines, IL-10 has a unique property which functions to suppress overall immunity. However, the functional role of IL-10 during the autophagic process has not been studied. In this study, we examined the effect of IL-10 during starvation induced autophagy of murine macrophages (J774). The results clearly indicated that IL-10 and IL-10 receptor signaling inhibits autophagy induction of murine macrophage. Further experiments revealed that IL-10 activates the class I phosphatidylinositol 3-kinase (PI3K) pathway, which results in the phosphorylation of p70S6K through the activation of Akt and a mammalian target of the rapamycin complex 1 (mTORC 1). These results will advance our understanding of the physiological function of IL-10 during the autophagic process of macrophage.

The mouse small ubiquitin-like modifier-2 (SUMO-2) inhibits interleukin-12 (IL-12) production in mature dendritic cells by blocking the translocation of the p65 subunit of NFκB into the nucleus.

Post-translational modification by small ubiquitin-like modifier (SUMO) is involved in several significant cellular events. In particular, SUMO-1 and SUMO-4 modifications of IκBα have been shown to be actively involved in NFκB regulation. However, among the SUMO family, the specific function of SUMO-2/3 remains relatively unknown. In addition, it is not clear whether SUMO-2/3 follows the same functional role as SUMO-1 and SUMO-4 during the activation of NFκB. In this study, we examined the influence of mouse SUMO-2 during the maturation of dendritic cells (DCs). Our results showed that the ectopic expression of SUMO-2 does not affect the cell surface expression of MHC class II molecule (A(b)) and co-stimulatory molecules (CD80 and CD86), and the efficiency of antigen uptake. However, the ectopic expression of mouse SUMO-2 inhibited IL-12 secretion by blocking the translocation of the p65 subunit of NFκB into the nucleus, which led to the polarization of naïve CD4(+) T cells to T helper 2 (Th2) shift in vitro. Further analyses showed that SUMO-2 directly modified IκBα. These results indicate that the functional role of SUMO-2/3 in the regulation of NFκB activity was conserved during evolution.

Autophagy induced by AXL receptor tyrosine kinase alleviates acute liver injury via inhibition of NLRP3 inflammasome activation in mice.

ABSTRACT Severe hepatic inflammation is a common cause of acute or chronic liver disease. Macrophages are one of the key mediators which regulate the progress of hepatic inflammation. Increasing evidence shows that the TAM (TYRO3, AXL and MERTK) family of RTKs (receptor tyrosine kinases), which is expressed in macrophages, alleviates inflammatory responses through a negative feedback loop. However, the functional contribution of each TAM family member to the progression of hepatic inflammation remains elusive. In this study, we explore the role of individual TAM family proteins during autophagy induction and evaluate their contribution to hepatic inflammation. Among the TAM family of RTKs, AXL (AXL receptor tyrosine kinase) only induces autophagy in macrophages after interaction with its ligand, GAS6 (growth arrest specific 6). Based on our results, autophosphorylation of 2 tyrosine residues (Tyr815 and Tyr860) in the cytoplasmic domain of AXL in mice is required for autophagy induction and AXL-mediated autophagy induction is dependent on MAPK (mitogen-activated protein kinase)14 activity. Furthermore, induction of AXL-mediated autophagy prevents CASP1 (caspase 1)-dependent IL1B (interleukin 1, β) and IL18 (interleukin 18) maturation by inhibiting NLRP3 (NLR family, pyrin domain containing 3) inflammasome activation. In agreement with these observations, axl−/− mice show more severe symptoms than do wild-type (Axl+/+) mice following acute hepatic injury induced by administration of lipopolysaccharide (LPS) or carbon tetrachloride (CCl4). Hence, GAS6-AXL signaling-mediated autophagy induction in murine macrophages ameliorates hepatic inflammatory responses by inhibiting NLRP3 inflammasome activation.

Trafficking of LAG-3 to the Surface on Activated T Cells via Its Cytoplasmic Domain and Protein Kinase C Signaling

Lymphocyte activation gene-3 (LAG-3; CD223), a structural homolog of CD4, binds to MHC class II molecules. Recent research indicated that signaling mediated by LAG-3 inhibits T cell proliferation, and LAG-3 serves as a key surface molecule for the function of regulatory T cells. Previous reports demonstrated that the majority of LAG-3 is retained in the intracellular compartments and is rapidly translocated to the cell surface upon stimulation. However, the mechanism by which LAG-3 translocates to the cell surface was unclear. In this study, we examined the trafficking of human LAG-3 under unstimulated as well as stimulated conditions of T cells. Under the unstimulated condition, the majority of LAG-3 did not reach the cell surface, but rather degraded within the lysosomal compartments. After stimulation, the majority of LAG-3 translocated to the cell surface without degradation in the lysosomal compartments. Results indicated that the cytoplasmic domain without Glu-Pro repetitive sequence is critical for the translocation of LAG-3 from lysosomal compartments to the cell surface. Moreover, protein kinase C signaling leads to the translocation of LAG-3 to the cell surface. However, two potential serine phosphorylation sites from the LAG-3 cytoplasmic domain are not involved in the translocation of LAG-3. These results clearly indicate that LAG-3 trafficking from lysosomal compartments to the cell surface is dependent on the cytoplasmic domain through protein kinase C signaling in activated T cells.

The ORF3 protein of porcine circovirus type 2 promotes secretion of IL-6 and IL-8 in porcine epithelial cells by facilitating proteasomal degradation of regulator of G protein signalling 16 through physical interaction.

Porcine circovirus type 2 (PCV2) is the main aetiological agent of postweaning multisystemic wasting syndrome. The mechanism of pathogenicity associated with PCV2 infection is still not fully understood. Nevertheless, the fact that large amounts of proinflammatory cytokines within lymphoid tissues are released during the early stage of PCV2 infection may induce chronic inflammatory responses followed by the destruction of lymphoid tissues. However, how PCV2 infection causes an excessive inflammatory response in the host immune system during the early stage of PCV2 infection has still not been elucidated. In this study, we show that direct interaction between the PCV2 ORF3 and regulator of G protein signalling 16 (RGS16) within the cytoplasm of host cells leads to ubiquitin-mediated proteasomal degradation of RGS16. Facilitated degradation of the RGS16 by PCV2 ORF3 further enhances NFκB translocation into the nucleus through the ERK1/2 signalling pathway and increased IL-6 and IL-8 mRNA transcripts. Consequently, more severe inflammatory responses and leukocyte infiltration occur around host cells. This evidence may be the first clue explaining the molecular basis of how excessive amounts of proinflammatory cytokines within lymphoid tissues are released during the early stage of PCV2 infection.

Human cytomegalovirus (HCMV) US2 protein interacts with human CD1d (hCD1d) and down-regulates invariant NKT (iNKT) cell activity.

To avoid host immune surveillance, human cytomegalovirus (HCMV) encoded endoplasmic reticulum (ER)-membrane glycoprotein US2, which interferes with antigen presenting mechanism of Major histocompatibility complex (MHC) class Ia and class II molecules. However, not many attempts have been made to study the effect of HCMV US2 on the expression of MHC class Ib molecules. In this study, we examined the effect of HCMV US2 on the expression and function of human CD1d (hCD1d), which presents glycolipid antigens to invariant NKT (iNKT) cells. Our results clearly showed that the physiological interaction between ER lumenal domain of HCMV US2 and α3 domain of hCD1d was observed within ER. Compared with mature form of hCD1d, immature form of hCD1d is more susceptible to ubiquitin-dependent proteasomal degradation mediated by HCMV US2. Moreover, the ectopic expression of HCMV US2 leads to the down-modulation of iNKT cell activity without significant change of hCD1d expression. These results will advance our understanding of the function of HCMV US2 in immune evasive mechanisms against anti-viral immunity of iNKT cells.

Saponins from soy bean and mung bean inhibit the antigen specific activation of helper T cells by blocking cell cycle progression

Treatment of helper T (Th) cells with saponins from soy bean and mung bean prevented their activation by inhibiting cell proliferation and cytokine secretion. However, the saponins did not affect the expression of major histocompatibility complex class II (Ab) and co-stimulatory molecule (CD86) on professional antigen-presenting cells. Instead, the saponins directly inhibited Th cell proliferation by blocking the G1 to S phase cell cycle transition. Moreover, blocking of the cell cycle by the saponins was achieved by decreased expression of cyclin D1 and cyclin E, and constitutive expression of p27KIP1. Saponins also increased stability of p27KIP1 in Th cells after antigenic stimulation.

The association between the self-perception period of overactive bladder symptoms and overactive bladder symptom scores in a non-treated population and related sociodemographic and lifestyle factors

Aims:  To investigate the association between the self‐perception period of OAB symptoms (SP‐OAB) and the overactive bladder symptom score (OABSS), along with related sociodemographic and lifestyle factors.

Generation and evaluation of the efficacy of rhesus monkey soluble cytotoxic T lymphocyte-associated antigen-4 in the allogeneic mixed lymphocyte reaction

Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4; CD152) is a transmembrane protein that is structurally similar to CD28. As CTLA-4 has a much higher binding affinity to B7 than CD28, several approaches using soluble CTLA-4 have been tried to down-regulate T cell activity by blocking the interaction between CD28 and B7. We constructed soluble rhesus monkey CTLA-4 immunoglobulin (CTLA-4Ig) containing a critical binding site to B7 combined with a constant Ig heavy chain region in a mammalian system. Flow cytometry analyses indicated that soluble rhesus monkey CTLA-4Ig bound to rhesus monkey CD86 (B7.2). Moreover, soluble rhesus monkey CTLA-4Ig more effectively blocked the rhesus monkey–rhesus monkey allogeneic mixed lymphocyte reaction compared with that of humans. These results indicate that soluble rhesus monkey CTLA-4Ig may be useful in preclinical trials in a rhesus monkey model.

Treatment satisfaction with low-dose tamsulosin for symptomatic benign prostatic hyperplasia: results from a multicentre cross-sectional survey

Aims:  To evaluate the efficacy and treatment satisfaction with low‐dose (0.2 mg) tamsulosin in patients with symptomatic benign prostatic hyperplasia (BPH), and to investigate individual lower urinary tract symptoms according to treatment satisfaction.