Phospholipase A2 inhibitor and LY6/PLAUR domain-containing protein PINLYP regulates type I interferon innate immunity.

Type I interferons (IFNs) are the first frontline of the host innate immune response against invading pathogens. Herein, we characterized an unknown protein encoded by phospholipase A2 inhibitor and LY6/PLAUR domain-containing (PINLYP) gene that interacted with TBK1 and induced type I IFN in a TBK1- and IRF3-dependent manner. Loss of PINLYP impaired the activation of IRF3 and production of IFN-ß induced by DNA virus, RNA virus, and various Toll-like receptor ligands in multiple cell types. Because PINLYP deficiency in mice engendered an early embryonic lethality in mice, we generated a conditional mouse in which PINLYP was depleted in dendritic cells. Mice lacking PINLYP in dendritic cells were defective in type I IFN induction and more susceptible to lethal virus infection. Thus, PINLYP is a positive regulator of type I IFN innate immunity and important for effective host defense against viral infection.

Photosensitizer-loaded hydrogels: A new antibacterial dressing.

Bacterial wound infection has emerged as a pivotal threat to human health worldwide, and the situation has worsened owing to the gradual increase in antibiotic-resistant bacteria caused by the improper use of antibiotics. To reduce the use of antibiotics and avoid the increase in antibiotic-resistant bacteria, researchers are increasingly paying attention to  photodynamic therapy, which uses light to produce reactive oxygen species to kill bacteria. Treating bacteria-infected wounds by photodynamic therapy requires fixing the photosensitizer (PS) at the wound site and maintaining a certain level of wound humidity. Hydrogels are materials with a high water content and are well suited for fixing PSs at wound sites for antibacterial photodynamic therapy. Therefore, hydrogels are often loaded with PSs for treating bacteria-infected wounds via antibacterial photodynamic therapy. In this review, we systematically summarised the antibacterial mechanisms and applications of PS-loaded hydrogels for treating bacteria-infected wounds via photodynamic therapy. In addition, the recent  studies and the research status progresses of novel antibacterial hydrogels are discussed. Finally, the challenges and future prospects of PS-loaded hydrogels are reviewed.

Musculin is highly enriched in Th17 and IL-22-producing ILC3s and restrains pro-inflammatory cytokines in murine colitis.

Transcription suppressor Musculin (MSC) is enriched in pro-inflammatory Th17 and IL-22-producing ILC3s. While MSC+/+ mice survived DSS-induced colitis, MSC-/- mice showed elevated pro-inflammatory cytokines with severer pathology, reduced body weight, and earlier death. Reversal of colitis symptoms in MSC-/- mice by IL-22 antagonism suggests the existence of MSC:IL-22 regulatory axis.

Association Between Variants of the Mannose-Binding Lectin 2 Gene and Susceptibility to Sepsis in the Hainan Island.

BACKGROUND Sepsis has emerged as a leading cause of death in the intensive care unit. A growing number of studies have shown that genetic variants, especially single nucleotide polymorphisms, are key determinants of inter-individual variation in sepsis response. Therefore, early prediction of the onset and progression of sepsis, along with early intervention in high-risk patients, should be performed to effectively reduce the morbidity and mortality of the disease. MATERIAL AND METHODS A total of 581 Chinese patients were enrolled in this study, including 271 patients with sepsis and 310 patients without. We measured gene polymorphisms of MBL2 and serum levels of MBL2, tumor necrosis factor (TNF-alpha), interleukin (IL)-6, IL-4, and IL-10 in all patients. The effects of site mutations on the binding of MBL2 to mannose-associated serine protease 1 (MASP1) and MASP2 were also analyzed. RESULTS Of 3 site mutations in the MBL2 gene (rs5030737, rs1800450, and rs1800451), only rs1800450 had a mutant (G/A) genotype. The frequency of the GA genotype and A allele in the sepsis group was higher than that in the non-sepsis group. Furthermore, rs1800450G/A was associated with decreased serum MBL2 and IL-10 levels and decreased MBL2-MASP1 and MBL2-MASP2 interactions. Bioinformatics analysis showed that rs1800450G/A reduced the structural stability of the MBL2 protein and affected its function. CONCLUSIONS MBL2 rs1800450G/A was associated with a higher risk of sepsis, which possibly involved a decreased level of serum MBL2 that broke the balance of inflammation and weakened the binding of MBL2 to MASP1 and MASP2.

Pretreatment optimization of tissue metabolomics in colorectal cancer.

BACKGROUND AND OBJECTIVES: To optimize the pretreatment method of colorectal cancer tissue samples for metabolomics research based on solid-phase nuclear magnetic resonance (NMR). METHODS AND STUDY DESIGN: The mucosal tissues of colorectal cancer were classified into five groups with a volume of 0.2 cm*0.2 cm*0.2 cm. The pretreatment methods for each group were as follows: I. Preservation with liquid nitrogen alone. Samples were also treated with liquid nitrogen for 10 (II), 20 (III), and 30 min (IV), respectively, immediately after isolation and then transferred to a -80℃ refrigerator; V. Only -80℃ refrigerator storage. No more than 30 minutes should pass between isolation and pretreatment of tumor samples. The tissue sample testing process was carried out on Bruker AVII-600 NMR Spectrometer. NMR signals were collected and analysed using partial least-squares discrimination analysis (PLS-DA) to explore the effects of different pretreatment methods on the metabolic changes of samples. RESULTS: The levels of pelargonic acid, stearic acid, D-Ribose, heptadecanoic acid, pyruvic acid, succinate, sarcosine, glycine, creatine, and L-lactate in the group I (only liquid nitrogen) were significantly lower than the other groups (p<0.05); the content of glycerophosphocholine in the group I (only liquid nitrogen) was lower than that in the other groups (p=0.055). These indicated that the glucose and choline phospholipid metabolism levels of the liquid nitrogen group were significantly lower than those of the other four groups. CONCLUSIONS: Liquid nitrogen storage can stop the metabolic process of glucose and choline phospholipid in colorectal cancer tissue samples in vitro, thus maintaining the metabolic state of tissue samples in vivo as much as possible.

Antibacterial Fusion Protein BPI21/LL-37 Modification Enhances the Therapeutic Efficacy of hUC-MSCs in Sepsis.

Sepsis, which is characterized by multiple organ dysfunctions as a result of an unbalanced host-inflammatory response to pathogens, is potentially a life-threatening condition and a major cause of death in the intensive care units (ICUs). However, effective treatment or intervention to prevent sepsis-associated lethality is still lacking. Human umbilical cord mesenchymal stem cell (hUC-MSC) transplantation has been shown to have potent immunomodulatory properties and improve tissue repair yet lacks direct antibacterial and endotoxin clearance activities. In this study, we engineered hUC-MSCs to express a broad-spectrum antibacterial fusion peptide containing BPI21 and LL-37 (named BPI21/LL-37) and confirmed that the BPI21/LL-37 modification did not affect the stemness and immunoregulatory capacities of hUC-MSCs but remarkably, enhanced its antibacterial and toxin-neutralizing activities in vitro. Furthermore, we showed that administration of BPI21/LL-37-engineered hUC-MSCs significantly reduces serum levels of tumor necrosis factor α (TNF-α), interleukin 1ß (IL-1ß), and IL-6, whereas increases that of IL-10 in cecal ligation and puncture (CLP)-induced sepsis mouse model. Administration of BPI21/LL-37-engineered hUC-MSCs significantly reduced systemic endotoxin (lipopolysaccharide [LPS]) levels and organ bacterial load, ameliorated damage to multiple organs, and improved survival. Taken together, our study demonstrates that BPI21/LL-37-engineered hUC-MSCs might offer a novel therapeutic strategy to prevent or treat sepsis via enhanced antimicrobial and anti-inflammatory properties to preserve organ functions better.

Agmatine Protects Against the Progression of Sepsis Through the Imidazoline I2 Receptor-Ribosomal S6 Kinase 2-Nuclear Factor-κB Signaling Pathway.

OBJECTIVES: The knowledge that agmatine is found in the human body has existed for several years; however, its role in sepsis has not yet been studied. In the present study, we investigate the role of agmatine in the progression and treatment of sepsis. DESIGN: Clinical/laboratory investigations. SETTING: Medical centers/University-based research laboratory. SUBJECTS: Elective ICU patients with severe sepsis and healthy volunteers; C57BL/6 mice weighing 18-22 g. INTERVENTIONS: Serum agmatine level and its associations with inflammatory markers were assessed in patients with sepsis. Agmatine was administered intraperitoneally to mice before a lipopolysaccharide challenge. Human peripheral blood mononuclear cells and murine macrophages were pretreated with agmatine followed by lipopolysaccharide stimulation. MEASUREMENTS AND MAIN RESULTS: Serum agmatine levels were significantly decreased in patients with sepsis and lipopolysaccharide-induced mice, and correlated with Acute Physiology and Chronic Health Evaluation II score, procalcitonin, tumor necrosis factor-α, and interleukin-6 levels. In a therapeutic experiment, exogenous agmatine attenuated the cytokine production of peripheral blood mononuclear cells from patients with sepsis and healthy controls. Agmatine also exerted a significant beneficial effect in the inflammatory response and organ damage and reduced the death rate in lipopolysaccharide-induced mice. Imidazoline I2 receptor agonist 2-benzofuran-2-yl blocked the pharmacological action of agmatine; whereas, other imidazoline receptor ligands did not. Furthermore, agmatine significantly impaired the inflammatory response by inactivating nuclear factor-κB, but not protein 38 mitogen-activated protein kinase, c-Jun N-terminal kinase, extracellular signal-regulated kinase, and inducible nitric oxide synthase signaling in macrophages. Activation of imidazoline I2 receptor or knockdown of ribosomal S6 kinase 2 counteracted the effects of agmatine on phosphorylation and degradation of inhibitor of nuclear factor-κBα. CONCLUSIONS: Endogenous agmatine metabolism correlated with the progression of sepsis. Supplemental exogenous agmatine could ameliorate the lipopolysaccharide-induced systemic inflammatory responses and multiple organ injuries through the imidazoline I2 receptor-ribosomal S6 kinase 2-nuclear factor-κB pathway. Agmatine could be used as both a clinical biomarker and a promising pharmaconutrient in patients with severe sepsis.

Cytochrome P450 1A1 enhances Arginase-1 expression, which reduces LPS-induced mouse peritonitis by targeting JAK1/STAT6.

The polarization of macrophages is critical to inflammation and tissue repair, with unbalanced macrophage polarization associated with critical dysfunctions of the immune system. Cytochrome P450 1A1 (CYP1A1) is a hydroxylase mainly controlled by the inflammation-limiting aryl hydrocarbon receptor (AhR), which plays a critical role in mycoplasma infection, oxidative stress injury, and cancer. Arginase-1 (Arg-1) is a surrogate for polarized alternative macrophages and is important to the production of nitric oxide (NO) by the modulation of arginine. In the present study, we found CYP1A1 to be upregulated in IL-4-stimulated mouse peritoneal macrophages (PMs) and human peripheral blood monocytes. Using CYP1A1-overexpressing RAW264.7 cells (CYP1A1/RAW) we found that CYP1A1 augmented Arg-1 expression by strengthening the activation of the JAK1/STAT6 signaling pathway in macrophages treated with IL-4. 15(S)-HETE, a metabolite of CYP1A1 hydroxylase, was elevated in IL-4-induced CYP1A1/RAW cells. Further, in macrophages, the loss-of-CYP1A1-hydroxylase activity was associated with reduced IL-4-induced Arg-1 expression due to impaired 15(S)-HETE generation. Of importance, CYP1A1 overexpressing macrophages reduced the inflammation associated with LPS-induced peritonitis. Taken together, these findings identified a novel signaling axis, CYP1A1-15(S)-HETE-JAK1-STAT6, that may be a promising target for the proper maintenance of macrophage polarization and may also be a means by which to treat immune-related disease due to macrophage dysfunction.

Neutrophilic granule protein (NGP) attenuates lipopolysaccharide-induced inflammatory responses and enhances phagocytosis of bacteria by macrophages.

Neutrophilic granule protein (NGP) belongs to the cystatin superfamily. Even though this superfamily is critically involved in cancer biology and adaptive immunity, the relationship of macrophage NGP to inflammation and phagocytosis remains poorly understood. In this study, we observed a significant increase of NGP in peritoneal macrophages (PMs) isolated from mice challenged with E. coli or lipopolysaccharide (LPS), as judged by NGP mRNA microarray. We also found changes in NGP to be mainly Toll-like receptor 4 (TLR4)-dependent. By western blot and electrophoretic mobility shift assay, we demonstrated NGP overexpression to reduce TNF-α and IL-1ß production by LPS-induced RAW264.7 cells (RAW) via suppression of the NF-κB (p65 and p50) signalling pathway, rather than the JNK1/AP-1 (fos and jun) signalling pathway. NGP overexpression by LPS-induced RAW also induced IL-10, an anti-inflammatory cytokine, which was partially involved in the anti-inflammatory effect produced by NGP overexpression. Moreover, upregulated NGP enhanced the phagocytosis of E. coli by RAW. Taken together, these results demonstrated NGP to be an important host defense component that regulates inflammatory responses and phagocytosis by activated macrophages. As such, NGP may be useful for the treatment of inflammatory based disease.

Cytochrome P450 1A1 enhances inflammatory responses and impedes phagocytosis of bacteria in macrophages during sepsis.

The hydroxylase cytochrome P450 1A1 (CYP1A1) is regulated by the inflammation-limiting aryl hydrocarbon receptor (AhR), but CYP1A1 immune functions remain unclear. We observed CYP1A1 overexpression in peritoneal macrophages (PMs) isolated from mice following LPS or heat-killed Escherichia. coli (E. coli) challenge. CYP1A1 overexpression augmented TNF-α and IL-6 production in RAW264.7 cells (RAW) by enhancing JNK/AP-1 signalling. CYP1A1 overexpression also promoted 12S-hydroxy-5Z,8Z,10E,14Z-eicosatetraenoic acid (12(S)-HETE) production in activated RAW, while a 12(S)-HETE antibody attenuated and 12(S)-HETE alone induced inflammatory responses. Macrophages harbouring hydroxylase-deficient CYP1A1 demonstrated reduced 12(S)-HETE generation and LPS-induced TNF-α/IL-6 secretion. CYP1A1 overexpression also impaired phagocytosis of bacteria via decreasing the expression of scavenger receptor A (SR-A) in PMs. Mice injected with CYP1A1-overexpressing PMs were more susceptible to CLP- or E. coli-induced mortality and bacteria invading, while Rhapontigenin, a selective CYP1A1 inhibitor, improved survival and bacteria clearance of mice in sepsis. CYP1A1 and 12(S)-HETE were also elevated in monocytes and plasma of septic patients and positively correlated with SOFA scores. Macrophage CYP1A1 disruption could be a promising strategy for treating sepsis. Video abstract.

Correction to: Cytochrome P450 1A1 enhances inflammatory responses and impedes phagocytosis of bacteria in macrophages during sepsis.

An amendment to this paper has been published and can be accessed via the original article.

Soluble Egg Antigen Activates M2 Macrophages via the STAT6 and PI3K Pathways, and Schistosoma Japonicum Alternatively Activates Macrophage Polarization to Improve the Survival Rate of Septic Mice.

Sepsis is one of the most challenging health problems worldwide. Our previous study showed that chronic schistosoma japonica (SJ) infection might increase serum anti-inflammatory factors to play a protective role, thus improving the survival rate of septic mice. Further research revealed that SJ infection promoted J774A.1 macrophage differentiation into M2 macrophages; suppressed LPS-induced activation of M1 macrophages; up-regulated CD163, IL-10, and TGF-ß1 expression; inhibited TNF-α and iNOS expression; and blocked the effect of LPS-promoted TNF-α and iNOS expression. Furthermore, adoptive transfer of ex vivo programed M2 macrophages significantly increased the survival rate of septic mice. In vitro studies suggested that soluble egg antigen (SEA) from SJ played the same role as worm infection but had no impact on M1 macrophages. SEA reduced LPS-induced TNF-α and iNOS expression, decreased the inhibitory effect of LPS on IL-10 and TGF-ß1 expression, increased STAT6 phosphorylation, and up-regulated PI3K and Akt expression but inhibited SOCS1 expression. When PI3K inhibitors were added, SEA-induced expression of CD163, IL-10, and arg1 might be reduced. Therefore, worm infection has a protective effect in septic mice in which SEA may play a key role via the STAT6 and PI3K pathways. This finding may provide a favorable solution for the treatment of sepsis, especially early cases. J. Cell. Biochem. 118: 4230-4239, 2017. © 2017 Wiley Periodicals, Inc.

The small-molecule inhibitor selectivity between IKKα and IKKß kinases in NF-κB signaling pathway.

The enzyme complex IκB kinase (IKK) is an essential activator of NF-κB signaling pathway involved in propagating the cellular response to inflammation. The complex contains two functional subunits IKKα and IKKß, which are structurally conserved kinases and selective inhibition of them would result in distinct biological effects. However, most existing IKK inhibitors show moderate or high promiscuity for the two homologous kinases. Understanding of the molecular mechanism and biological implication underlying the specific interactions in IKK-ligand recognition is thus fundamentally important for the rational design of selective IKK inhibitors. In the current work, we integrated molecular docking, quantum mechanics/molecular mechanics calculation and Poisson-Boltzmann/surface area analysis to investigate the structural basis and energetic property of the selective binding of small-molecule ligands to IKKα and IKKß. It was found that the selectivity is primarily determined by the size and topology difference in ATP-binding pocket of IKKα and IKKß kinase domains; bulky inhibitor molecules commonly have, respectively, low and appropriate affinities towards IKKα and IKKß, and thus exhibit relatively high selectivity for IKKß over IKKα, whereas small ligands can only bind weakly to both the two kinases with low selectivity. In addition, the conformation, arrangement and distribution of residues in IKK pockets are also responsible for constituting the exquisite specificity of ligand binding to KKα and IKKß. Next, a novel quantitative structure-selectivity relationship model was developed to characterize the relative contribution of each kinase residue to inhibitor selectivity and to predict the selectivity and specificity for a number of known IKK inhibitors. Results showed that the active-site residues contribute significantly to the selectivity by directly interacting with inhibitor ligands, while those protein portions far away from the kinase active sites may also play an important role in determining the selectivity through long-range non-bonded forces and indirect allosteric effect.

Role of speckle tracking imaging in the assessment of myocardial regional ventricular function in experimental blunt cardiac injury.

PURPOSE: To evaluate the usefulness and information collecting ability of speckle tracking imaging techniques in the assessment of myocardial regional ventricular contractility in a rabbit model with blunt cardiac injury. METHODS: Fifteen healthy New Zealand rabbits weighing (2.70 ±0.28) kg were anesthetized (3% pentobarbital sodium/i.v) and impacted using the BIM-II biological impact machine to induce myocardial contusion (MC). Hemodynamic parameters, such as heart rate, systolic pressure, mean arterial pressure, diastolic pressure and central venous pressure, were determined before and after MC. Further, parameters reflecting left ventricular functions, such as left ventricular end systolic pressure, left ventricular end diastolic pressure, isovolumic pressure (IP) and the maximal increasing/decreasing rate of left intraventricular pressure (±dp/dtmax), were also determined before and after MC. Left ventricular functions were determined either by two dimensional transthoracic echocardiography or by speckle tracking imaging for segmental abnormal ventricular wall motions. RESULTS: Heart rate, systolic pressure, diastolic pressure and mean arterial pressure decreased significantly but transiently, while central venous pressure markedly increased after MC. In contrast to significant changes in diastolic functions, there was no significant change in cardiac systolic functions after MC. The speckle tracking imaging demonstrated that strain values of different myocardial segment significantly decreased post impact, and that of the ventricular segment decreased from segment to segment. CONCLUSION: Speckle tracking imaging is useful and informative to assess myocardial regional dysfunctions post MC.

[Role and mechanism of gut microbiota and its metabolites in host defense against infection].

The interaction of gut microbiota and its metabolites with the host not only plays an important role in maintaining gut homeostasis and host health, but also is a key link in responding to pathogen infections. A thorough understanding of the changes in gut microbiota and its metabolites during infection, as well as their role and mechanism in host defense against infection, is helpful to guide anti-infection treatment. This review focuses on the role of gut microbiota and their metabolites in host defense against bacterial, fungal, and viral infections, and reveals that they can exert anti-infection effects through resistance mechanisms (inducing antimicrobial substances, training immunity, inhibiting pathogen respiration, directly neutralizing pathogens, immune regulation) and tolerance mechanisms (altering energy metabolism patterns of microbiota, cell proliferation and tissue damage repair, maintaining physiological signal transduction in extraintestinal organs, inflammation regulation, maintaining the integrity of the intestinal barrier), and also summarizes measures to regulate gut microbiota against pathogen infections, in order to provide more ideas for novel anti-infection prevention and treatment strategies targeting gut microbiota and its metabolites.

Current advances and future trends of hormesis in disease.

Hormesis, an adaptive response, occurs when exposure to low doses of a stressor potentially induces a stimulatory effect, while higher doses may inhibit it. This phenomenon is widely observed across various organisms and stressors, significantly advancing our understanding and inspiring further exploration of the beneficial effects of toxins at doses both below and beyond traditional thresholds. This has profound implications for promoting biological regulation at the cellular level and enhancing adaptability throughout the biosphere. Therefore, conducting bibliometric analysis in this field is crucial for accurately analyzing and summarizing its current research status. The results of the bibliometric analysis reveal a steady increase in the number of publications in this field over the years. The United States emerges as the leading country in both publication and citation numbers, with the journal Dose-Response publishing the highest number of papers in this area. Calabrese E.J. is a prominent person with significant contributions and influence among authors. Through keyword co-occurrence and trend analysis, current hotspots in this field are identified, primarily focusing on the relationship between hormesis, oxidative stress, and aging. Analysis of highly cited references predicts that future research trends may center around the relationship between hormesis and stress at different doses, as well as exploring the mechanisms and applications of hormesis. In conclusion, this review aims to visually represent hormesis-related research through bibliometric methods, uncovering emerging patterns and areas of focus within the field. It provides a summary of the current research status and forecasts trends in hormesis-related research.

WTAP/YTHDF1-mediated m6A modification amplifies IFN-γ-induced immunosuppressive properties of human MSCs.

INTRODUCTION: The immunosuppressive capacity of mesenchymal stem cells (MSCs) is dependent on the "license" of several pro-inflammatory factors to express immunosuppressive molecular profiles, which determines the therapeutic efficacy of MSCs in immune-mediated inflammatory diseases. Of those, interferon-γ (IFN-γ) is a key inducer for the expression of immunosuppressive molecular profiles; however, the mechanism underlying this effect is unknown. OBJECTIVES: To elucidate the regulation mechanism and biological functions of N6-methyladenosine (m6A) modification in the immunosuppressive functions by the IFN-γ-licensing MSCs. METHODS: Epitranscriptomic microarray analysis and MeRIP-qPCR assay were performed to identify the regulatory effect of WTAP in the IFN-γ-licensing MSCs. RIP-qPCR, western blot, qRT-PCR and RNA stability assays were used to determine the regulation of WTAP/m6A/YTHDF1 signaling axis in the expression of immunosuppressive molecules. Further, functional capacity of T cells was tested using flow cytometry, and both DSS-induced colitis mice and CIA mice were constructed to clarify the effect of WTAP and YTHDF1 in MSC-mediated immunosuppression. RESULTS: We identified that IFN-γ increased the m6A methylation levels of immunosuppressive molecules, while WTAP deficiency abolished the IFN-γ-induced promotion of m6A modification. IFN-γ activated ERK signaling, which induced WTAP phosphorylation. Additionally, the stabilization of WTAP post-transcriptionally increased the mRNA expression of immunosuppressive molecules (IDO1, PD-L1, ICAM1, and VCAM1) in an m6A-YTHDF1-dependent manner; this effect further impacted the immunosuppressive capacity of IFN-γ licensing MSCs on activated T cells. Notably, WTAP/YTHDF1 overexpression enhanced the therapeutic efficacy of IFN-γ licensing MSCs and restructures the ecology of inflammation in both colitis and arthritis models. CONCLUSION: Our results showed that m6A modification of IDO1, PD-L1, ICAM1, and VCAM1 mRNA mediated by WTAP-YTHDF1 is involved in the regulation of IFN-γ licensing MSCs immunosuppressive abilities, and shed a light to enhance the clinical therapeutic potential of IFN-γ-licensing MSCs.

Punicalagin promotes mincle-mediated phagocytosis of macrophages via the NF-κB and MAPK signaling pathways.

Punicalagin (PUN) is a polyphenol derived from the pomegranate peel. It has been reported to have many beneficial effects, including anti-inflammatory, anti-oxidant, and anti-proliferation. However, the role of PUN in macrophage phagocytosis is currently unknown. In this study, we found that pre-treatment with PUN significantly enhanced phagocytosis by macrophages in a time- and dose-dependent manner in vitro. Moreover, KEGG enrichment analysis by RNA-sequencing showed that differentially expressed genes following PUN treatment were significantly enriched in phagocyte-related receptors, such as the C-type lectin receptor signaling pathway. Among the C-type lectin receptor family, Mincle (Clec4e) significantly increased at the mRNA and protein level after PUN treatment, as shown by qRT-PCR and western blotting. Small interfering RNA (siRNA) mediated knockdown of Mincle in macrophages resulted in down regulation of phagocytosis. Furthermore, western blotting showed that PUN treatment enhanced the phosphorylation of nuclear factor kappa-B (NF-κB) and mitogen-activated protein kinase (MAPK) in macrophages at the early stage. Mincle-mediated phagocytosis by PUN was inhibited by PDTC (a NF-κB inhibitor) and SB203580 (a p38 MAPK inhibitor). In addition, PUN pre-treatment enhanced phagocytosis by peritoneal and alveolar macrophages in vivo. After intraperitoneal injection of Escherichia coli (E.coli), the bacterial load of peritoneal lavage fluid and peripheral blood in PUN pre-treated mice decreased significantly. Similarly, the number of bacteria in the lung tissue significantly reduced after intranasal administration of Pseudomonas aeruginosa (PAO1). Taken together, our results reveal that PUN enhances bacterial clearance in mice by activating the NF-κB and MAPK pathways and upregulating C-type lectin receptor expression to enhance phagocytosis by macrophages.

Stromal cell-derived factor-1 enhances wound healing through recruiting bone marrow-derived mesenchymal stem cells to the wound area and promoting neovascularization.

Stromal cell-derived factor-1 (SDF-1) is a potent chemokine for bone marrow-derived stromal stem cells (BMSCs) that express CXCR4, the receptor for SDF-1. SDF-1 is considered to play an important role in the trafficking of BMSCs. We investigated the contribution of SDF-1 to the recruitment of BMSCs to the wound area and its promotion of wound repair and neovascularization. BMSCs were pretreated with or without anti-CXCR4 blocking antibody and combined with CM-DiI label, and injected via the tail vein into mice with full-thickness skin wounds on the dorsum. Simultaneously, anti-SDF-1 antibody was injected into local wounds in another group of mice. The results show that blockade of CXCR4 on either infused BMSCs or SDF-1 in the host wounds (1) dramatically impaired the number of infused BMSCs being recruited to the injured tissue, (2) reduced the expression of growth factors involved in the repair of injured tissue such as vascular endothelial growth factor, basic fibroblast growth factor and transforming growth factor beta 1, (3) decreased the resultant neovascularization, and (4) retarded wound healing. Taken together, the findings indicate that the SDF-1/CXCR4 signal pathway facilitates wound healing through augmenting BMSC recruitment to wound tissues, responsive secretion of growth factors by BMSCs and neovascularization in the wound area.