Allograft or Recipient ST2 Deficiency Oppositely Affected Cardiac Allograft Vasculopathy via Differentially Altering Immune Cells Infiltration.

The role of IL-33/ST2 signaling in cardiac allograft vasculopathy (CAV) is not fully addressed. Here, we investigated the role of IL-33/ST2 signaling in allograft or recipient in CAV respectively using MHC-mismatch murine chronic cardiac allograft rejection model. We found that recipients ST2 deficiency significantly exacerbated allograft vascular occlusion and fibrosis, accompanied by increased F4/80+ macrophages and CD3+ T cells infiltration in allografts. In contrast, allografts ST2 deficiency resulted in decreased infiltration of F4/80+ macrophages, CD3+ T cells and CD20+ B cells and thus alleviated vascular occlusion and fibrosis of allografts. These findings indicated that allografts or recipients ST2 deficiency oppositely affected cardiac allograft vasculopathy/fibrosis via differentially altering immune cells infiltration, which suggest that interrupting IL-33/ST2 signaling locally or systematically after heart transplantation leads different outcome.

An Autocrine Circuit of IL-33 in Keratinocytes Is Involved in the Progression of Psoriasis.

IL-33 is constitutively expressed in the skin. Psoriasis is a common skin inflammatory disease. The roles of IL-33 in psoriasis have not been well-elucidated. We identified that keratinocytes (KCs) are the predominant cells expressing IL-33 and its receptor, suppression of tumorigenicity 2, in the skin. KCs actively released IL-33 on psoriasis inflammatory stimuli and induced psoriasis-related cytokine, chemokine, and inflammatory molecules genes transcription in KCs in an autocrine manner. IL-33‒specific deficiency in KCs ameliorated imiquimod-induced psoriatic dermatitis. In addition, intradermal injection of recombinant IL-33 alone induced psoriasis-like dermatitis, which is attributed to the transcriptional upregulation of genes enriched in IL-17, TNF, and chemokine signaling pathway in KCs on recombinant IL-33 stimulation. Our data demonstrate that the autocrine circuit of IL-33 in KCs promotes the progression of psoriatic skin inflammation, and IL-33 is a potential therapeutic target for psoriasis.

Plasmacytoid dendritic cell deficiency in neonates enhances allergic airway inflammation via reduced production of IFN-α.

Allergic asthma, a chronic inflammatory airway disease associated with type 2 cytokines, often originates in early life. Immune responses at an early age exhibit a Th2 cell bias, but the precise mechanisms remain elusive. Plasmacytoid dendritic cells (pDCs), which play a regulatory role in allergic asthma, were shown to be deficient in neonatal mice. We report here that this pDC deficiency renders neonatal mice more susceptible to severe allergic airway inflammation than adult mice in an OVA-induced experimental asthma model. Adoptive transfer of pDCs or administration of IFN-α to neonatal mice prevented the development of allergic inflammation in wild type but not in IFNAR1-/- mice. Similarly, adult mice developed more severe allergic inflammation when pDCs were depleted. The protective effects of pDCs were mediated by the pDC-/IFN-α-mediated negative regulation of the secretion of epithelial cell-derived CCL20, GM-CSF, and IL-33, which in turn impaired the recruitment of cDC2 and ILC2 cells to the airway. In asthmatic patients, the percentage of pDCs and the level of IFN-α were lower in children than in adults. These results indicate that impairment of pDC-epithelial cell crosstalk in neonates is a susceptibility factor for the development of allergen-induced allergic airway inflammation.

Toll-like receptor 2 deficiency promotes the generation of alloreactive Th17 cells after cardiac transplantation in mice.

The emergence of alloreactive Th17 cells that mediate allograft rejection has provided an impetus to understand the factors affecting the generation of Th17 cells in allograft transplantation. How toll-like receptor 2 (TLR2) signalling regulates the generation of Th17 cells upon alloantigen stimuli remains unclear. In this study, we used a mouse model of cardiac allograft transplantation to investigate whether TLR2 signalling influences the development of Th17 cells. Here, we demonstrate that the TLR2-deficient recipient mice show high Th17 cells, both in spleens and allografts, as well as higher infiltrating inflammatory leukocytes in cardiac allografts compared to wild-type control recipient mice. mRNA expression of IL-17, IL-6, TNF-α, CCR6 and CCL20 within the allografts is markedly increased in TLR2-deficient recipient mice compared to wild-type recipient mice. In addition, TLR2 deficiency leads to upregulation of Signal transducer and activator of transcription 3 (STAT3) phosphorylation in both spleens and allografts. In an in vitro experiment, a mixed lymphocyte reaction was assessed, which further confirmed that TLR2 deficiency leads to a significant increase in the generation of Th17 cells compared with wild-type controls. Furthermore, IL-6 secreted by the dendritic cells of TLR2-deficient mice contributes to driving the generation of these Th17 cells. These results suggest that TLR2 signalling is important in regulating the development of Th17 cells after cardiac allograft transplantation.

The macrophage-specific V-ATPase subunit ATP6V0D2 restricts inflammasome activation and bacterial infection by facilitating autophagosome-lysosome fusion.

Macroautophagy/autophagy is a conserved ubiquitous pathway that performs diverse roles in health and disease. Although many key, widely expressed proteins that regulate autophagosome formation followed by lysosomal fusion have been identified, the possibilities of cell-specific elements that contribute to the autophagy fusion machinery have not been explored. Here we show that a macrophage-specific isoform of the vacuolar ATPase protein ATP6V0D2/subunit d2 is dispensable for lysosome acidification, but promotes the completion of autophagy via promotion of autophagosome-lysosome fusion through its interaction with STX17 and VAMP8. Atp6v0d2-deficient macrophages have augmented mitochondrial damage, enhanced inflammasome activation and reduced clearance of Salmonella typhimurium. The susceptibility of atp6v0d2 knockout mice to DSS-induced colitis and Salmonella typhimurium-induced death, highlights the in vivo significance of ATP6V0D2-mediated autophagosome-lysosome fusion. Together, our data identify ATP6V0D2 as a key component of macrophage-specific autophagosome-lysosome fusion machinery maintaining macrophage organelle homeostasis and, in turn, limiting both inflammation and bacterial infection. Abbreviations: ACTB/ß-actin: actin, beta; ATG14: autophagy related 14; ATG16L1: autophagy related 16-like 1 (S. cerevisiae); ATP6V0D1/2: ATPase, H+ transporting, lysosomal V0 subunit D1/2; AIM2: absent in melanoma 2; BMDM: bone marrow-derived macrophage; CASP1: caspase 1; CGD: chronic granulomatous disease; CSF1/M-CSF: colony stimulating factor 1 (macrophage); CTSB: cathepsin B; DSS: dextran sodium sulfate; IL1B: interleukin 1 beta; IL6: interleukin 6; IRGM: immunity-related GTPase family M member; KO: knockout; LAMP1: lysosomal-associated membrane protein 1; LC3: microtubule-associated protein 1 light chain 3; LPS: lipo-polysaccaride; NLRP3: NLR family, pyrin domain containing 3; PYCARD/ASC: PYD and CARD domain containing; SNARE: soluble N-ethylmaleimide-sensitive factor attachment protein receptor; SNAP29: synaptosomal-associated protein 29; SQSTM1/p62: sequestosome 1; STX17: syntaxin 17; TLR: toll-like receptor; TNF: tumor necrosis factor ; TOMM20: translocase of outer mitochondrial membrane 20; ULK1: unc-51 like kinase 1; VAMP8: vesicle-associated membrane protein 8; WT: wild type; 3-MA: 3-methyladenine.

Lactate inhibits ATP6V0d2 expression in tumor-associated macrophages to promote HIF-2α-mediated tumor progression.

Macrophages perform key functions in tissue homeostasis that are influenced by the local tissue environment. Within the tumor microenvironment, tumor-associated macrophages can be altered to acquire properties that enhance tumor growth. Here, we found that lactate, a metabolite found in high concentration within the anaerobic tumor environment, activated mTORC1 that subsequently suppressed TFEB-mediated expression of the macrophage-specific vacuolar ATPase subunit ATP6V0d2. Atp6v0d2-/- mice were more susceptible to tumor growth, with enhanced HIF-2α-mediated VEGF production in macrophages that display a more protumoral phenotype. We found that ATP6V0d2 targeted HIF-2α but not HIF-1α for lysosome-mediated degradation. Blockade of HIF-2α transcriptional activity reversed the susceptibility of Atp6v0d2-/- mice to tumor development. Furthermore, in a cohort of patients with lung adenocarcinoma, expression of ATP6V0d2 and HIF-2α was positively and negatively correlated with survival, respectively, suggesting a critical role of the macrophage lactate/ATP6V0d2/HIF-2α axis in maintaining tumor growth in human patients. Together, our results highlight the ability of tumor cells to modify the function of tumor-infiltrating macrophages to optimize the microenvironment for tumor growth.

Effects of mimicked acetylated HMGB1 on macrophages and dendritic cells.

Extracellular high mobility group box 1 (HMGB1) serves a critical role in inflammatory diseases. HMGB1 is released into the extracellular environment mainly by passive release from necrotic cells or active secretion from monocytes/macrophages following stimulation. However, the translocation of actively secreted HMGB1 from the nucleus to the cytoplasm with post­translational modifications such as acetylation is required; HMGB1 is then released into the extracellular space. Whether acetylation influences the extracellular function of HMGB1 remains unknown. In the present study, an optimized method of gene mutation by using well­designed primers in particular, which were employed to identify the mutant gene. The substitution of six lysine residues for glutamines was conducted to mimic acetylated HMGB1 (HMGB1­M) and observe the effects of HMGB1­M on macrophages and dendritic cells (DCs). Tumor necrosis factor (TNF)­α production in RAW 264.7 cells was assessed by ELISA. The phagocytic potential of RAW 264.7 cells, DC maturation and CXCR4 expression were analyzed by flow cytometry. The results of the present study revealed that HMGB1­M increased cytoplasmic translocation. Compared with HMGB1, HMGB1­M increased TNF­α production within RAW 264.7 cells and decreased the mean fluorescence intensity (MFI) of integrin α X, and the percentage and MFI of major histocompatibility complex­II on DCs. HMGB1­M exhibited no significant effects on phagocytosis of macrophages and expression frequency of cluster of differentiation 80 and chemokine receptor type 4 on DCs. These results suggested that HMGB1­M may partly promote inflammation and decrease DC maturation. Thus, the findings of the present study may provide insight into the complex role of HMGB1 in inflammatory diseases.

Interleukin-33 deficiency exacerbated experimental autoimmune encephalomyelitis with an influence on immune cells and glia cells.

Interleukin (IL)-33, a member of the IL-1 cytokine family, is highly expressed in central nervous system (CNS), suggesting its potential role in CNS. Although some studies have focused on the role of IL-33 in multiple sclerosis (MS) / experimental autoimmune encephalomyelitis (EAE), an autoimmune disease characterized by demyelination and axonal damage in CNS, the exact role of IL-33 in MS/EAE remains unclear and controversial. Here, we used IL-33 knockout mice to clarify the role of endogenous IL-33 in EAE by simultaneously eliminating its role as a nuclear transcription factor and an extracellular cytokine. We found that the clinical score in IL-33 knockout EAE mice was higher accompanied by more severe demyelination compared with the wild-type (WT) EAE mice. As for the main immune cells participating in EAE in IL-33 knockout mice, pathogenic effector T cells increased both in peripheral immune organs and CNS, while CD4+FOXP3+ regulatory T cells decreased in spleen and lymph nodes, Th2 cells and natural killer (NK) cells decreased in CNS. Additionally, the populations of microglia/macrophages and CD11C+CD11B+ dendritic cells (DCs) increased in CNS of IL-33 knockout mice with EAE, among which iNOS-producing microglia/macrophages increased. Moreover, resident astrocytes/microglia were more activated in IL-33 knockout mice with EAE. In vitro, after blocking the IL-33, the proliferation of primary astrocytes, the production of MCP-1/CCL2 and TNF-α by astrocytes, and the production of TNF-α by primary microglia stimulated by the homogenate of the peak stage of EAE were increased. Our results indicate that IL-33 plays a protective role in EAE and exerts extensive influences on multiple immune cells and neural cells involved in EAE.

Glycyrrhizin Protects Mice Against Experimental Autoimmune Encephalomyelitis by Inhibiting High-Mobility Group Box 1 (HMGB1) Expression and Neuronal HMGB1 Release.

The inflammatory mediator high-mobility group box 1 (HMGB1) plays a critical role in the pathogenesis of human multiple sclerosis (MS) and mouse experimental autoimmune encephalomyelitis (EAE). Glycyrrhizin (GL), a glycoconjugated triterpene extracted from licorice root, has the ability to inhibit the functions of HMGB1; however, GL's function against EAE has not been thoroughly characterized to date. To determine the benefit of GL as a modulator of neuroinflammation, we used an in vivo study to examine GL's effect on EAE along with primary cultured cortical neurons to study the GL effect on HMGB1 release. Treatment of EAE mice with GL from onset to the peak stage of disease resulted in marked attenuation of EAE severity, reduced inflammatory cell infiltration and demyelination, decreased tumor necrosis factor-alpha (TNF-α), IFN-γ, IL-17A, IL-6, and transforming growth factor-beta 1, and increased IL-4 both in serum and spinal cord homogenate. Moreover, HMGB1 levels in different body fluids were reduced, accompanied by a decrease in neuronal damage, activated astrocytes and microglia, as well as HMGB1-positive astrocytes and microglia. GL significantly reversed HMGB1 release into the medium induced by TNF-α stimulation in primary cultured cortical neurons. Taken together, the results indicate that GL has a strong neuroprotective effect on EAE mice by reducing HMGB1 expression and release and thus can be used to treat central nervous system inflammatory diseases, such as MS.

Inhibition of autophagy with 3-methyladenine is protective in a lethal model of murine endotoxemia and polymicrobial sepsis.

Here, the regulatory role of autophagy is examined in both an LPS-induced lethal endotoxic shock mouse model and cecal ligation and puncture (CLP) mouse model. Autophagy-inhibitor 3-methyladenine (3-MA) and autophagy-enhancer rapamycin were administrated to mice challenged with LPS or CLP. Animals challenged with LPS or CLP combined with 3-MA displayed increased survival after endotoxemia, but LPS combined with rapamycin worsened the endotoxic shock of the mice. Among the different organs studied, the lungs and intestines exhibited significant differences among LPS alone, LPS combined with 3-MA and LPS combined with rapamycin. LPS combined with 3-MA attenuated the inflammatory damages of these organs as compared with LPS alone. In contrast, LPS combined with rapamycin increased damage in these organs. Consistently, serum inflammatory mediators TNF-α and IL-6 were decreased by the treatment of LPS combined with 3-MA as compared with LPS alone, while administration of LPS combined with rapamycin increased the serum TNF-α and IL-6 levels. Similar results were found in mouse bone marrow-derived macrophages exposed to LPS. Moreover, the regulatory effect of autophagy to endotoxic shock is dependent on the TLR4 signaling pathway. Our results demonstrate the central role of autophagy in the regulation of endotoxic shock and its potential modulation for endotoxic shock treatment.

GRP78 Impairs Production of Lipopolysaccharide-Induced Cytokines by Interaction with CD14.

The 78-kDa glucose-regulated protein (GRP78) is a stress-inducible chaperone that resides primarily in the endoplasmic reticulum. GRP78 has been described to be released at times of cellular stress and as having extracellular properties that are anti-inflammatory or favor the resolution of inflammation. In the current study, we confirmed that GRP78 impaired the production of lipopolysaccharide-induced pro-inflammatory cytokines in GRP78-treated bone-marrow-derived dendritic cells (DCs). To explore the underlying mechanism, first of all, GRP78 was checked to be bound to the plasma membrane. Interestingly, such binding promoted endocytosis of toll-like receptor (TLR) 4 and reduction in TLR4 on the plasma surface had a key role in desensitization of GRP78-treated DCs to lipopolysaccharide. Given that cluster of differentiation (CD)14 is a crucial regulator of TLR4 endocytosis, interaction of GRP78 with CD14 was investigated next. Data showed that GRP78 co-localized with CD14 on the plasma membrane and glutathione-S-transferase-GRP78 precipitated CD14. In CD14 knockout mice, down-regulation of tumor necrosis factor-α and reduction in TLR4 on the plasma surface were abrogated in GRP78-treated DCs. Overall, these data suggested that GRP78 mediates endocytosis of TLR4 by targeting CD14 to favor the resolution of inflammation.

Glycyrrhizin ameliorates experimental colitis through attenuating interleukin-17-producing T cell responses via regulating antigen-presenting cells.

Glycyrrhizin, a component of Chinese medicine licorice root, has the ability to inhibit the functions of high-mobility group box 1 (HMGB1). While glycyrrhizin is known to have anti-inflammatory activities, the underlying mechanisms by which glycyrrhizin inhibits inflammation during the development of trinitrobenzenesulfonic acid (TNBS)-induced experimental colitis are not well understood. This study systemically examined the regulatory effects of glycyrrhizin on inflammatory response in TNBS-induced murine colitis and explored the potential mechanisms involved in this process. We reported that glycyrrhizin treatment ameliorated colitis and decreased the production of inflammatory mediators HMGB1, IFN-γ, IL-6, TNF-α, and IL-17. In addition, glycyrrhizin regulated responses of dendritic cells (DCs) and macrophages during the development of colitis. Furthermore, administration of glycyrrhizin suppressed the proliferation of Th17 cells in colitis. Moreover, the ability of DCs and macrophages to induce the differentiation of Th17 cells was enhanced in presence of HMGB1, which was inhibited by glycyrrhizin. These results demonstrated that glycyrrhizin alleviated colitis by inhibiting the promotive effect of HMGB1 on DC/macrophage-mediated Th17 proliferation. In conclusion, HMGB1 plays an important role in the development of colitis. As an inhibitor of HMGB1, glycyrrhizin might be a novel therapy for colitis.

Association between an elevated level of HMGB1 and non-small-cell lung cancer: a meta-analysis and literature review.

BACKGROUND: HMGB1 has been overexpressed in the tissues or serum of patients with non-small-cell lung cancer (NSCLC) in several studies. However, the results remain inconsistent. OBJECTIVE: The aim of this study was to perform a meta-analysis to investigate the relationship between elevated level of HMGB1 and NSCLC. METHODS: Associated studies were included, and the pooled risk difference and mean difference (MD) together with 95% confidence interval (CI) were calculated. RESULTS: A total of ten relevant studies on HMGB1 expression were included in this meta-analysis. The pooled results suggested that the expression of HMGB1 in NSCLC tissues was notably higher than those in corresponding nontumor normal tissues by using immu-nohistochemistry (risk difference =0.38, 95% CI: 0.28-0.48, Z=7.67, P<0.00001, I (2)=0%), Western blot (MD =0.27, 95% CI: 0.06-0.47, Z=2.57, P<0.01), or real-time polymerase chain reaction (MD =15.15, 95% CI: 14.8-15.5, Z=2.08, P=0.04). Serum HMGB1 levels were similarly significantly higher in patients with NSCLC than those in healthy controls. The pooled MDs of HMGB1 in patients with NSCLC compared with healthy controls were 17.54 with 95% CI: 10.99-24.09, Z=5.25, P<0.00001. Two of the included studies were fully reviewed without performing meta-analysis due to the different detection methods used. The protein level of HMGB1 in patients with NSCLC of tumor, nodes, and metastasis (TNM) stages III-IV was higher than that of TNM stages I-II (P<0.047 and P<0.001, respectively). CONCLUSION: The expression levels of HMGB1 in both tissues and serum of patients with NSCLC were statistically higher than those of normal lung samples, which indicated that elevated levels of HMGB1 can reveal changes that correlated with disease progression, or even the risk of NSCLC disease progression. The elevated level of HMGB1 could also be considered as a potential biomarker for the diagnosis of patients with NSCLC.

CD27 natural killer cell subsets play different roles during the pre-onset stage of experimental autoimmune encephalomyelitis.

NK cells participate in the development of human multiple sclerosis (MS) and mouse experimental autoimmune encephalomyelitis (EAE), but the roles of different NK cell subsets in disease onset remain poorly understood. In this study, murine NK cells were divided into CD27(high) and CD27(low/-) subsets. The CD27(high) subset was decreased and the CD27(low/-) subset was increased in lymphoid organs during the pre-onset stage of EAE. Compared with the counterpart in naïve mice, the CD27(high) subset showed lower expression of Ly49D, Ly49H and NKG2D, and less production of IFN-γ, whereas the CD27(low/-) subset showed similar expression of the above mentioned surface receptors but higher cytotoxic activity in EAE mice. Compared with the CD27(high) subset, the CD27(low/-) subset exhibited increased promotion of DC maturation and no significant inhibition of T cells proliferation and Th17 cells differentiation in vitro Additionally, adoptive transfer of the CD27(low/-) subset, but not the CD27(high) subset, exacerbated the severity of EAE. Collectively, our data suggest the CD27 NK cell subsets play different roles in controlling EAE onset, which provide a new understanding for the regulation of NK cell subsets in early autoimmune disease.

Kupffer-cell-expressed transmembrane TNF-α is a major contributor to lipopolysaccharide and D-galactosamine-induced liver injury.

Tumor necrosis factor (TNF)-α exists in two bioactive forms, a 26-kDa transmembrane form (tmTNF-α) and a 17-kDa soluble form (sTNF-α). sTNF-α has been recognized as a key regulator of hepatitis; however, serum sTNF-α disappears in mice during the development of severe liver injury, and high levels of serum sTNF-α do not necessarily result in liver damage. Interestingly, in a mouse model of acute hepatitis, we have found that tmTNF-α expression on Kupffer cells (KCs) significantly increases when mice develop severe liver injury caused by lipopolysaccharide (LPS)/D-galactosamine (D-gal), and the level of tmTNF-α expression is positively related to the activity of serum transaminases. Therefore, we hypothesized that KC-expressed tmTNF-α constitutes a pathomechanism in hepatitis and have explored the role of tmTNF-α in this disease model. Here, we have compared the impact of KCs(tmTNFlow) and KCs(tmTNFhigh) on acute hepatitis in vivo and ex vivo and have further demonstrated that KCs(tmTNFhigh), rather than KCs(tmTNFlow), not only exhibit an imbalance in secretion of pro- and anti-inflammatory cytokines, favoring inflammatory response and exacerbating liver injury, but also induce hepatocellular apoptosis via tmTNF-α and the expression of another pro-apoptotic factor, Fas ligand. Our data suggest that KC(tmTNFhigh) is a major contributor to liver injury in LPS/D-gal-induced hepatitis.

BIP induces mice CD19(hi) regulatory B cells producing IL-10 and highly expressing PD-L1, FasL.

Many studies have shown that B cells possess a regulatory function in mouse models of autoimmune diseases. Regulatory B cells can modulate immune response through many types of molecular mechanisms, including the production of IL-10 and the expression of PD-1 Ligand and Fas Ligand, but the microenvironmental factors and mechanisms that induce regulatory B cells have not been fully identified. BIP (binding immunoglobulin protein), a member of the heat shock protein 70 family, is a type of evolutionarily highly conserved protein. In this article, we have found that IL-10(+), PD-L1(hi) and FasL(hi) B cells are discrete cell populations, but enriched in CD19(hi) cells. BIP can induce IL-10-producing splenic B cells, IL-10 secretion and B cells highly expressing PD-L1 and FasL. CD40 signaling acts in synergy with BIP to induce regulatory B cells. BIP increased surface CD19 molecule expression intensity and IL-10(+), PD-L1(hi) and FasL(hi) B cells induced by BIP share the CD19(hi) phenotype. Furthermore, B cells treated with BIP and anti-CD40 can lead to suppression of T cell proliferation and the effect is partially IL-10-dependent and mainly BIP-induced. Taken together, our findings identify a novel function of BIP in the induction of regulatory B cells and add a new reason for the therapy of autoimmune disorders or other inflammatory conditions.

Transmembrane tumor necrosis factor-alpha sensitizes adipocytes to insulin.

Transmembrane TNF-α (tmTNF-α) acts both as a ligand, delivering 'forward signaling' via TNFR, and as a receptor, transducing 'reverse signaling'. The contradiction of available data regarding the effect of tmTNF-α on insulin resistance may be due to imbalance in both signals. Here, we demonstrated that high glucose-induced impairment of insulin-stimulated glucose uptake by 3T3-L1 adipocytes was concomitant with decreased tmTNF-α expression and increased soluble TNF-α (sTNF-α) secretion. However, when TACE was inhibited, preventing the conversion of tmTNF-α to sTNF-α, this insulin resistance was partially reversed, indicating a salutary role of tmTNF-α. Treatment of 3T3-L1 adipocytes with exogenous tmTNF-α promoted insulin-induced phosphorylation of IRS-1 and Akt, facilitated GLUT4 expression and membrane translocation, and increased glucose uptake while addition of sTNF-α resulted in the opposite effect. Furthermore, tmTNF-α downregulated the production of IL-6 and MCP-1 via NF-κB inactivation, as silencing of A20, an inhibitor for NF-κB, by siRNA, abolished this effect of tmTNF-α. However, tmTNF-α upregulated adiponectin expression through the PPAR-γ pathway, as inhibition of PPAR-γ by GW9662 abrogated both tmTNF-α-induced adiponectin transcription and glucose uptake. Our data suggest that tmTNF-α functions as an insulin sensitizer via forward signaling.

In vitro differentiation of human adipose tissue-derived stem cells into islet-like clusters promoted by islet neogenesis-associated protein pentadecapeptide.

Human adipose tissue-derived stem cells (hASCs) are considered an ideal tool for the supply of insulin-producing cells to treat diabetes mellitus, with high differentiation efficiency. Islet neogenesis-associated protein (INGAP) is an initiator of islet neogenesis, and the peptide sequence comprising amino acids 104-118, named INGAP pentadecapeptide (INGAP-PP), has been shown to increase ß-cell mass in animals and human pathological states. Here, we report a novel 4-step method to promote hASCs to differentiate into islet-like clusters (ILCs) more efficiently by adding INGAP-PP. The hASCs were isolated, purified and differentiated using a 4-step protocol including trichostatin A, INGAP-PP/scrambled peptide (Scrambled-P), dexamethasone, nicotinamide, glucagon-like peptide-1, transforming growth factor ß1 and exendin-4. Results showed that ILCs in the INGAP-PP group were more similar to the fresh islets with regard to both size and morphology and expressed significantly higher levels of both insulin and C-peptide than those in the Scrambled-P group. Moreover, the ILCs from the INGAP-PP group secreted higher levels of insulin and C-peptide than those from the Scrambled-P group in response to both a low (5.6 mM) and high (25 mM) glucose challenge and secreted 6 times more hormones under the high-glucose challenge. Real-time PCR and immunocytochemistry showed that ILCs of the INGAP-PP group expressed human pancreatic endocrine hormones and transcription factors. Transplantation of ILCs into diabetic rats partially reversed diabetes and prolonged their life span. In conclusion, the INGAP-PP protocol can efficiently induce hASCs to differentiate into ILCs in vitro, and thus hASCs could be a promising source of cells for transplantation to treat diabetes mellitus.

Collagenase digestion down-regulates the density of CD27 on lymphocytes.

Collagenases are widely used for tissue digestion in experiments due to their potent hydrolysis of connective tissue. CD27, also known as tumor necrosis factor receptor superfamily 7 (TNFRSF7), is limited to be expressed on the cells of the lymphoid lineage. In our preliminary research, we found that CD27 on NK cells was almost disappeared with the digestion of type I collagenase for 90min. This phenomenon suggests that the process of tissue digestion may affect the density of CD27 on cells. In order to verify this, the lungs of mice were digested with types I and IV collagenase or grinded, respectively. The percentage of CD27(+) cells and the density of CD27 on cells were assayed by flow cytometry. The data presented that the percentage of CD27(+) cells and the density of CD27 on lymphocytes gradually decreased with the time of digestion with type I or IV collagenase. We also detected that the density of CD11b on NK cells was not affected by collagenase digestion. Collectively, the findings of the present study suggest that the collagenase digestion has a selective effect on the density of molecules on cells.