Cathelicidin-WA polarizes E. coli K88-induced M1 macrophage to M2-like macrophage in RAW264.7 cells

Escherichia coli K88 activates NLRP3 inflammasome-mediated pyroptosis in vitro and in vivo

Pyroptosis induced by lipopolysaccharide (LPS) has an obvious impact on intestinal inflammation and immune regulation. Enterotoxigenic Escherichia coli (ETEC) K88 has been proved to induce inflammatory responses in several models, but whether E. coli K88 participates in the same process of pyroptotic cell death as LPS remains to be identified. We conducted a pilot experiment to confirm that E. coli K88, instead of Escherichia coli O157 and Salmonella typhimurium, promotes the secretion of interleukin-1 beta (IL-1β) and interleukin-18 (IL-18) in macrophages. Further experiments were carried out to dissect the molecular mechanism both in vitro and in vivo. The Enzyme-Linked Immunosorbent Assay (ELISA) results suggested that E. coli K88 treatment increased the expression of pro-inflammatory cytokines IL-18 and IL-1β in both C57BL/6 mice and the supernatant of J774A.1 cells. Intestinal morphology observations revealed that E. coli K88 treatment mainly induced inflammation in the colon. Real-time PCR and Western blot analysis showed that the mRNA and protein expressions of pyroptosis-related factors, such as NLRP3, ASC, and Caspase1, were significantly upregulated by E. coli K88 treatment. The RNA-seq results confirmed that the effect was associated with the activation of NLRP3, ASC, Caspase1, GSDMD, IL-18, and IL-1β, and might also be related to inflammatory bowel disease and the tumor necrosis factor pathway. The pyroptosis-activated effect of E. coli K88 was significantly blocked by NLRP3 siRNA. Our data suggested that E. coli K88 caused inflammation by triggering pyroptosis, which provides a theoretical basis for the prevention and treatment of ETEC in intestinal infection.

Synergistic antibacterial and antifouling wound dressings: Integration of photothermal-activated no release and zwitterionic surface modification

Addressing the pervasive issue of bacteria and biofilm infections is crucial in the development of advanced antifouling wound dressings. In this study, a novel wound healing treatment using sulfobetaine (SBMA) decorated electrospun fibrous membrane based on polycaprolactone (PCL)/nitric oxide (NO) donors was developed. The fabrication involved a dual strategy, first integrating NO donors into mesoporous polydopamine (MPDA) and complexed with PCL/PEI to electrospin nanofibers. The fibrous membrane exhibited a potent antibacterial response upon irradiation at 808 nm, owing to a combination of NO and photothermal effect that effectively targets bacteria and disrupts biofilms. Surface functionalization of the membrane with PEI allowed for the attachment of SBMA via Michael addition, fabricating a zwitterionic surface, which significantly hinders protein adsorption and reduces biofilm formation on the wound dressing. In vitro and in vivo assessments confirmed the rapid bactericidal capabilities and its efficacy in biofilm eradication. Combining photothermal activity, targeted NO release and antifouling surface, this multifaceted wound dressing addresses key challenges in bacterial infection management and biofilm eradication, promoting efficient wound healing.

Lycopene promoted M2 macrophage polarization via inhibition of NOTCH1-PI3K-mTOR-NF-κB-JMJD3-IRF4 pathway in response to Escherichia coli infection in J744A.1 cells

Escherichia coli (E. coli) can induce severe clinical bovine mastitis, which is to blame for large losses experienced by dairy farms. Macrophage polarization into various states is in response to pathogen infections. Lycopene, a naturally occurring hydrocarbon carotenoid, relieved inflammation by controlling M1/M2 status of macrophages. Thus, we wanted to explore the effect of lycopene on polarization states of macrophages in E. coli-induced mastitis. Macrophages were cultivated with lycopene for 24, before E. coli inoculation for 6 h. Lycopene (0.5 μmol/L) significantly enhanced cell viabilities and significantly reduced lactic dehydrogenase (LDH) levels in macrophages, whereas 2 and 3 μmol/L lycopene significantly enhanced LDH activities. Lycopene treatment significantly reduced the increase in LDH release, iNOS, CD86, TNF-α, IL-1β and phosphatase and tensin homolog (PTEN) expressions in E. coli group. 0.5 μmol/L lycopene significantly increased E. coli-induced downregulation of CD206, arginase I (ARG1), indoleamine 2,3-dioxygenase (IDO), chitinase 3-like 3 (YM1), PI3K, AKT, p-AKT, mammalian target of rapamycin (mTOR), p-mTOR, jumonji domain-containing protein-3 (JMJD3) and interferon regulatory factor 4 (IRF4) levels. Moreover, Ginkgolic acid C17:1 (a specific PTEN inhibitor), 740YPDGFR (a specific PI3K activator), SC79 (a specific AKT activator) or CHPG sodium salt (a specific NF-κB activator) significantly decreased CD206, AGR1, IDO and YM1 expressions in lycopene and E. coli-treated macrophages. Therefore, lycopene increased M2 macrophages via inhibiting NOTCH1-PI3K-mTOR-NF-κB-JMJD3-IRF4 pathway in response to E. coli infection in macrophages. These results contribute to revealing the pathogenesis of E. coli-caused bovine mastitis, providing the new angle of the prevention and management of mastitis.

A systematic strategy for investigating the pharmacological effects and mechanism of traditional Chinese medicinal formula: Guilin Xiguashuang as a case

BACKGROUND

Traditional Chinese medicinal formula (TCMF) has specific advantages in treating diseases. However, the pharmacological effects and mechanism of TCMF composed of traditional Chinese medicines (TCM) with unclear active components or targets have not yet been fully elucidated.

OBJECTIVES

This research proposed a strategy for elucidating the pharmacological effects and mechanism to address this issue systematically.

METHODS

With Guilin Xiguashuang (GLXGS) taken as a case, this study newly provided the multi-level assays, which decomposes TCMF into components, TCM, and TCMF levels. The main pharmacological effects were acquired through a comprehensive analysis based on the active components, pharmacological effects of TCM, and clinical efficacy of TCMF, respectively. The core targets and pathways were further identified and verified to elucidate the mechanism.

RESULTS

The main pharmacological effects of GLXGS were anti-inflammatory, analgesic, antibacterial, immunoregulatory, and wound healing. Moreover, the mechanism analysis demonstrated that GLXGS was involved in the regulation of NF-κB and VEGF signaling pathways and core targets, such as IL-6 and TNF-α. Finally, unproven immunomodulatory and anti-inflammatory mechanism were verified using RAW264.7 and THP-1 cells. GLXGS was verified to down-regulate IL-6, IL-1β, TNF-α, and CD86 in lipopolysaccharides-stimulated RAW264.7 cells, while enhancing polarization in both RAW264.7 and THP-1 cells, which were consistent with analysis results.

CONCLUSION

The present research provides a systematic strategy for the pharmacological effect prediction and mechanism analysis of TCMF, which is of great significance for studying complex TCMF.

Peptide-Based Biomaterials for Bone and Cartilage Regeneration

The healing of osteochondral defects (OCDs) that result from injury, osteochondritis, or osteoarthritis and bear lesions in the cartilage and bone, pain, and loss of joint function in middle- and old-age individuals presents challenges to clinical practitioners because of non-regenerative cartilage and the limitations of current therapies. Bioactive peptide-based osteochondral (OC) tissue regeneration is becoming more popular because it does not have the immunogenicity, misfolding, or denaturation problems associated with original proteins. Periodically, reviews are published on the regeneration of bone and cartilage separately; however, none of them addressed the simultaneous healing of these tissues in the complicated heterogeneous environment of the osteochondral (OC) interface. As regulators of cell adhesion, proliferation, differentiation, angiogenesis, immunomodulation, and antibacterial activity, potential therapeutic strategies for OCDs utilizing bone and cartilage-specific peptides should be examined and investigated. The main goal of this review was to study how they contribute to the healing of OCDs, either alone or in conjunction with other peptides and biomaterials.

Peptide-containing nanoformulations: Skin barrier penetration and activity contribution

Transdermal drug delivery presents a less invasive pathway, circumventing the need to pass through the gastrointestinal tract and liver, thereby reducing drug breakdown, initial metabolism, and gastrointestinal discomfort. Nevertheless, the unique composition and dense structure of the stratum corneum present a significant barrier to transdermal delivery. This article presents an overview of the current developments in peptides and nanotechnology to address this challenge. Initially, we sum up peptide-containing nanoformulations for transdermal drug delivery, examining them through the lenses of both inorganic and organic materials. Particular emphasis is placed on the diverse roles that peptides play within these nanoformulations, including conferring functionality upon nanocarriers and enhancing the biological efficacy of drugs. Subsequently, we summarize innovative strategies for enhancing skin penetration, categorizing them into passive and active approaches. Lastly, we discuss the therapeutic potential of peptide-containing nanoformulations in addressing a range of diseases, drawing insights from the biological activities and functions of peptides. Furthermore, the challenges hindering clinical translation are also discussed, providing valuable insights for future advancements in transdermal drug delivery.

Tree Frog-Derived Cathelicidin Protects Mice against Bacterial Infection through Its Antimicrobial and Anti-Inflammatory Activities and Regulatory Effect on Phagocytes

Due to excessive use or abuse in the food industry, agriculture, and medicine, many pathogens are developing resistance against conventional antibiotics. Antimicrobial peptides (AMPs) hold promise as effective therapeutic options for the treatment of bacterial infections. Herein, a novel cathelicidin antimicrobial peptide (Zs-CATH) was identified from the tree frog Zhangixalus smaragdinus. Zs-CATH mainly adopted an amphipathic β-sheet structure in a membrane-mimetic environment. It showed broad-spectrum antibacterial activity against Gram-positive and Gram-negative bacteria in vitro and significantly protected mice from lethal infections induced by Gram-negative bacteria Escherichia coli ATCC 25922 or Gram-positive bacteria Staphylococcus aureus ATCC 25923 in vivo. In addition, Zs-CATH exerted a strong anti-inflammatory effect by neutralizing lipopolysaccharide (LPS) and lipoteichoic acid (LTA) and promoting macrophage M2 polarization, thus inhibiting the secretion of proinflammatory cytokines (TNF-α, IL-6, and IL-1β) and enhancing the production of M2 macrophage markers IL-10, IL-4, and CD206. The MAPK and NF-κB inflammatory signaling pathways and transcriptional activator 6 (STAT6) were involved in this effect. In mice, Zs-CATH rapidly recruited neutrophils and monocytes/macrophages to the abdominal cavity but not T and B lymphocytes. Zs-CATH did not exhibit a direct chemoattractant effect on phagocytes but significantly promoted phagocyte migration in the presence of macrophages. Zs-CATH stimulated macrophages to secrete chemokines CXCL1, CXCL2, and CCL2, which mediated the recruitment of phagocytes. Furthermore, Zs-CATH promoted the production of reactive oxygen species (ROS) and neutrophil extracellular traps (NETs), which are oxygen-dependent and oxygen-independent mechanisms of the microbicidal activity of neutrophils, respectively. Zs-CATH exhibited no toxic side effects on mammalian cells and mice. These findings show that in addition to direct antibacterial activity, Zs-CATH also possesses the ability to modulate immune and inflammatory processes during bacterial infection, showing potential for development as anti-infective and/or anti-inflammatory agents.

Sialidase facilitates Porphyromonas gingivalis immune evasion by reducing M1 polarization, antigen presentation, and phagocytosis of infected macrophages

Background

Porphyromonas gingivalis (P. gingivalis), a major pathogen of periodontitis, can evade host immune defenses. Previously, we found that P. gingivalis W83 sialidase gene mutant strain (ΔPG0352) was more easily cleared by macrophages. The aims of this study were to investigate the effects of sialidase in P. gingivalis on the polarization, antigen presentation, and phagocytosis of infected macrophages and to clarify the mechanism of P. gingivalis immune evasion.

Methods

Human monocytes U937 were differentiated to macrophages and infected with P. gingivalis W83, ΔPG0352, comΔPG0352, and Escherichia coli (E. coli). The phagocytosis of macrophages was observed by transmission electron microscopy and flow cytometry. ELISA or Griess reaction were used to examine the levels of interleukin-12 (IL-12), inducible nitric oxide synthase (iNOS) and interleukin-10 (IL-10), and the expressions of CD68, CD80 and CD206 were determined by flow cytometry. The expression of major histocompatibility complex-II (MHC-II) was detected by immunofluorescence. A rat periodontitis model was established to determine the M1 and M2 polarization of macrophages.

Results

Compare with P. gingivalis W83, ΔPG0352 increased the levels of IL-12, iNOS, CD80, and MHC-II and inhibited the levels of IL-10 and CD206. Macrophages phagocytosed 75.4% of ΔPG0352 and 59.5% of P. gingivalis W83. In the rat periodontitis model, the levels of M1 and M2 macrophages in P. gingivalis W83 group were both higher than those in ΔPG0352 group, while the ratio of M1/M2 was higher in the ΔPG0352 group. Alveolar bone absorption was lower in ΔPG0352 group.

Conclusion

Sialidase facilitates P. gingivalis immune evasion by reducing M1 polarization, antigen presentation, and phagocytosis of infected macrophages.

Role of antimicrobial peptide cathelicidin in thrombosis and thromboinflammation

Thrombosis is a frequent cause of cardiovascular mortality and hospitalization. Current antithrombotic strategies, however, target both thrombosis and physiological hemostasis and thereby increase bleeding risk. In recent years the pathophysiological understanding of thrombus formation has significantly advanced and inflammation has become a crucial element. Neutrophils as most frequent immune cells in the blood and their released mediators play a key role herein. Neutrophil-derived cathelicidin next to its strong antimicrobial properties has also shown to modulates thrombosis and thus presents a potential therapeutic target. In this article we review direct and indirect (immune- and endothelial cell-mediated) effects of cathelicidin on platelets and the coagulation system. Further we discuss its implications for large vessel thrombosis and consecutive thromboinflammation as well as immunothrombosis in sepsis and COVID-19 and give an outlook for potential therapeutic prospects.

Trihydroxyxanthones from the heartwood of Maclura cochinchinensis modulate M1/M2 macrophage polarisation and enhance surface TLR4

The anti-inflammatory actions of phytochemicals have attracted much attention due to the current state of numerous inflammatory disorders. Thai traditional medicine uses Maclura cochinchinensis (Lour.) Corner to treat chronic fever and various inflammatory diseases, as well as to maintain normal lymphatic function. Five flavonoids and five xanthones were isolated from the heartwood of M. cochinchinensis and we investigated the anti-inflammatory properties of the isolated compounds. All isolated compounds possessed an anti-inflammatory effect by decreasing prostaglandin E₂ (PGE₂) synthesis in lipopolysaccharide (LPS)-activated murine macrophages with varying degrees of potency. The greatest decrease in M1 inflammatory mediators, nitric oxide, PGE₂, and proinflammatory cytokines was observed with 1,3,7-trihydroxyxanthone and 1,3,5-trihydroxyxanthone treatment of LPS-activated macrophages. The anti-inflammatory mechanism of the two xanthones is mediated by the suppression of inducible nitric oxide synthase, cyclooxygenase-2, and phosphatidylinositol 3-kinase/protein kinase B expression and the upregulation of M2 anti-inflammatory signalling proteins phosphorylated signal transducer and activator of transcription 6 and peroxisome proliferator-activated receptors-γ. 1,3,7-Trihydroxyxanthone exhibits superior induction of anti-inflammatory M2 mediator of LPS-activated macrophages by upregulating arginase1 expression. Following the resolution of inflammation, the two xanthones enhanced surface TLR4 expression compared to LPS-stimulated cells, possibly preserving macrophage function. Our research highlights the role of the two xanthones in modulating the M1/M2 macrophage polarisation to reduce inflammation and retain surface TLR4 once inflammation has been resolved. These findings support the use of xanthones for their anti-inflammatory effects in treating inflammatory dysregulation.

Study on the imbalance of M1/M2 macrophage polarization in severe chronic periodontitis

BACKGROUND

Macrophages commonly exist in two distinct subsets in different microenvironments: classically activated macrophages (M1) and alternatively activated macrophages (M2). The imbalance of M1-M2 macrophage polarization is often related to various diseases or inflammatory states.

OBJECTIVE

The purpose of this study was to determine whether there is an imbalance in the expression of M1 and M2 macrophage-related cytokines in severe chronic periodontitis.

METHODS

A total of 30 clinical specimens, including severe chronic periodontitis tissues (n= 15) and healthy control tissues (n= 15), were used in this study. Reverse transcription polymerase chain reaction (RT-PCR) and Western blot methods were used to detect the mRNA and protein expression levels of M1 macrophage-related cytokines (inducible nitric oxide synthase (iNOS) and signal transducer and activator of transcription 1 (STAT1)) and M2 macrophage-related cytokines (arginase-1 (Arg-1) and STAT6), respectively.

RESULTS

The mRNA and protein expression levels of M1 macrophage-related cytokines (iNOS and STAT1) and M2 macrophage-related cytokines (Arg-1 and STAT6) were significantly increased in severe chronic periodontitis patients. In addition, the ratios of iNOS/Arg-1 and STAT1/STAT6 in the severe chronic periodontitis group were also significantly increased (P< 0.01).

CONCLUSION

The imbalance of M1/M2 macrophages exists in the pathogenesis of severe chronic periodontitis, and has a tendency towards M1 polarization. Therefore, maintaining the immune balance of M1/M2 macrophages may be a novel therapeutic alternative for the management of severe chronic periodontitis.

Antimicrobial peptides for bone tissue engineering: Diversity, effects and applications

Bone tissue engineering has been becoming a promising strategy for surgical bone repair, but the risk of infection during trauma repair remains a problematic health concern worldwide, especially for fracture and infection-caused bone defects. Conventional antibiotics fail to effectively prevent or treat bone infections during bone defect repair because of drug-resistance and recurrence, so novel antibacterial agents with limited resistance are highly needed for bone tissue engineering. Antimicrobial peptides (AMPs) characterized by cationic, hydrophobic and amphipathic properties show great promise to be used as next-generation antibiotics which rarely induce resistance and show potent antibacterial efficacy. In this review, four common structures of AMPs (helix-based, sheet-based, coil-based and composite) and related modifications are presented to identify AMPs and design novel analogs. Then, potential effects of AMPs for bone infection during bone repair are explored, including bactericidal activity, anti-biofilm, immunomodulation and regenerative properties. Moreover, we present distinctive applications of AMPs for topical bone repair, which can be either used by delivery system (surface immobilization, nanoparticles and hydrogels) or used in gene therapy. Finally, future prospects and ongoing challenges are discussed.

Myeloid Angiotensin II Type 1 Receptor Mediates Macrophage Polarization and Promotes Vascular Injury in DOCA/Salt Hypertensive Mice

Activation of the renin–angiotensin system has been implicated in hypertension. Angiotensin (Ang) II is a potent proinflammatory mediator. The present study investigated the role of myeloid angiotensin type 1 receptor (AT1R) in control of macrophage phenotype in vitro and vascular injury in deoxycorticosterone acetate (DOCA)/salt hypertension. In human THP-1/macrophages, Ang II increased mRNA expressions of M1 cytokines and decreased M2 cytokine expressions. Overexpression of AT1R further increased Ang II-induced expressions of M1 cytokines and decreased M2 cytokines. Silenced AT1R reversed Ang II-induced changes in M1 and M2 cytokines. Ang II upregulated hypoxia-inducible factor (HIF)1α, toll-like receptor (TLR)4, and the ratio of pIκB/IκB, which were prevented by silenced AT1R. Silenced HIF1α prevented Ang II activation of the TLR4/NFκB pathway. Furthermore, Ang II increased HIF1α via reactive oxygen species-dependent reduction in prolyl hydroxylase domain protein 2 (PHD2) expression. The expressions of AT1R and HIF1α and the ratio of pIκB/IκB were upregulated in the peritoneal macrophages of DOCA hypertensive mice, and the specific deletion of myeloid AT1R attenuated cardiac and vascular injury and vascular oxidative stress, reduced the recruitment of macrophages and M1 cytokine expressions, and improved endothelial function without significant reduction in blood pressure. Our results demonstrate that Ang II/AT1R controls the macrophage phenotype via stimulating the HIF1α/NFκB pathway, and specific myeloid AT1R KO improves endothelial function, vascular inflammation, and injury in salt-sensitive hypertension. The results support the notion that myeloid AT1R plays an important role in the regulation of the macrophage phenotype, and dysfunction of this receptor may promote vascular dysfunction and injury in salt-sensitive hypertension.

Butyric Acid Ameliorates Myocardial Fibrosis by Regulating M1/M2 Polarization of Macrophages and Promoting Recovery of Mitochondrial Function

Background

We aimed to investigate the effect and mechanism of butyric acid on rat myocardial fibrosis (MF).

Methods

16S rRNA sequencing was used to analyze the gut microbiota characteristics of the Sham group and MF group. HPLC was applied to measure butyric acid in the feces and serum. In vitro, rat macrophages RMa-bm were stimulated with LPS and IL-4, respectively, and then butyrate was added to study the influences of butyrate on M1/M2 polarization and mitochondrial function of rat macrophages. The rat macrophages and rat myocardial fibroblasts were co-cultured to explore the effect of butyrate on rat myocardial fibroblasts. In addition, MF rats were fed with butyric acid diet.

Results

Compared with the Sham group, collagen deposition in the MF group was increased, and fibrosis was serious. The abundance of Desulfovibrionaceae and Helicobacteraceae in the MF group was increased compared with the Sham group. Gut epithelial cells were destroyed in the MF group compared with the Sham group. Compared with the Sham group, LPS content in the MF group was increased and butyric acid was decreased. Butyrate inhibited M1 and promoted M2. Furthermore, butyrate may promote mitochondrial function recovery by regulating M1/M2 polarization of macrophages. After adding butyrate, cell proliferation ability was decreased, and aging and apoptosis were increased, which indicated that butyrate inhibited rat myocardial fibroblasts activity. Moreover, butyric acid could protect mitochondria and improve the symptoms of rats with MF.

Conclusions

Butyric acid ameliorated MF by regulating M1/M2 polarization of macrophages and promoting recovery of mitochondrial function.

Human Umbilical Cord Mesenchymal Stem Cells Improve the Necrosis and Osteocyte Apoptosis in Glucocorticoid-Induced Osteonecrosis of the Femoral Head Model through Reducing the Macrophage Polarization

Background and Objectives

Apoptosis is an outstanding determinant of glucocorticoid (GC)-induced osteonecrosis of the femoral head (ONFH). Human umbilical cord mesenchymal stem cells (hUC-MSCs) have been demonstrated to be associated with apoptosis in diseases models. However, the role of hUC-MSCs in GC-induced ONFH via regulating apoptosis still needs further study.

Methods and Results

In the present study, a GC-induced ONFH model was built in vivo through a consecutive injection with lipopolysaccharide (LPS) and methylprednisolone. The necrosis and apoptosis of the femoral head was evaluated by histological and Terminal-deoxynucleoitidyl Transferase Mediated Nick End Labeling (TUNEL) assay. The level of collagen and TRAP positive cells were determined by Masson and TRAP staining, respectively. M1 macrophage polarization was assessed using immunofluorescence assay. The level of proinflammatory cytokines including tumor necrosis factor (TNF)‐α, Interleukin (IL)‐1β and IL-6 of femoral head was determined by enzyme-linked immunosorbent assay (ELISA) kits. The protein expression of AKT, mTOR, p-AKT and p-mTOR was detected using western blot assay. The results showed that hUC-MSCs treatment prominently promoted the GC-induced the decrease of the collagen level and the increase of TRAP positive cells. Besides, hUC-MSCs treatment decreased necrosis and apoptosis, macrophage polarization, the level of TNF‐α, IL‐1β and IL-6, the protein expression of p-AKT and p-mTOR, and the radio of p-AKT to AKT and p-mTOR to mTOR of femoral head in vivo.

Conclusions

Therefore, the present study revealed that hUC-MSCs improved the necrosis and osteocyte apoptosis in GC-induced ONFH model through reducing the macrophage polarization, which was associated with the inhibition of AKT/mTOR signaling pathway.

Cathelicidin-WA ameliorates diabetic cardiomyopathy by inhibiting the NLRP3 inflammasome

Cathelicidin-WA (CWA) is a novel cathelicidin peptide isolated from snakes that has been suggested to exert anti-inflammatory effects. The aim of our study was to investigate whether cathelicidin-WA (CWA) could protect the heart from diabetic cardiomyopathy (DCM). Streptozotocin (STZ) injection was used to establish a mouse model of DCM. CWA peptide (2 mg/kg or 8 mg/kg) was continuously administered to the mice from 10 weeks to 16 weeks after STZ injection. The mice in the DCM group exhibited cardiac dysfunction, while 8 mg/kg CWA ameliorated this cardiac dysfunction. Cardiac fibrosis, inflammation, and oxidative stress as well as cardiomyocyte apoptosis in the DCM mice were decreased by treatment with 8 mg/kg CWA. We isolated neonatal rat cardiomyocytes and stimulated the cells with high glucose to establish an in vitro model of myocyte cell injury. Consistently, CWA inhibited high glucose-induced cell death, inflammation and oxidative stress in the myocytes. Moreover, CWA reduced the formation of the NLR family pyrin domain-containing 3 (NRLP3) inflammasome by regulating thioredoxin-interacting protein expression and p65 activation. NLRP3 overexpression inhibited the beneficial effects of CWA on the heart during DCM and on high glucose-induced myocyte injury. In summary, CWA attenuates cardiac injury and preserves cardiac function during DCM by targeting the NLRP3 pathway.Abbreviations: AAV9: Adeno associated virus; AGE: Advanced Glycation End products; CWA: Cathelicidin-WA; DCM: diabetic cardiomyopathy; Gpx: glutathione peroxidase; HG: high glucose; IL: Interleukin; NLR: Family Pyrin Domain Containing 3 (NRLP3); TXNIP: Thioredoxin interacting protein; LVEF: left ventricular ejection fraction; MDA: Malondialdehyde; MnSOD: manganese superoxide dismutase; NADPH: Nicotinamide adenine dinucleotide phosphate; NAC: N-acetyl-cysteine; NRCMs: Neonatal rat cardiomyocytes; ROS: reactive oxygen species; STZ: Streptozotocin; TNFa: tumor necrosis factor a.

Multivalent effects of heptamannosylated β-cyclodextrins on macrophage polarization to accelerate wound healing

Macrophages have high plasticity and heterogeneity, and can suppress or mediate inflammation, depending on their cytokine secretion and phenotype. Regulating macrophage polarization into its M2 phenotype has a remarkable effect on inflammatory inhibition, inducing the regeneration of injured tissues. Here, we synthesized two heptamannosylated β-cyclodextrin derivatives (CD-Man7 and C₃-CD-Man7) and demonstrated that their multivalent mannose ligands could induce M2 macrophage polarization to accelerate wound healing. Unlike hydrophilic CD-Man7, amphiphilic C₃-CD-Man7 can self-assemble to form nanoparticles (CD-Man-NPs) in aqueous solution. Further, in vitro results confirmed that multivalent mannose ligands of either CD-Man7 or CD-Man-NPs stimulated RAW264.7 macrophages to differentiate into the M2 phenotype, which promoted fibroblast migration via a paracrine mechanism. In vivo results confirmed that both CD-Man7 and CD-Man-NPs reduced the inflammatory response in wound tissue and accelerated wound healing. The present study demonstrates multivalent effects of CD-Man7 and CD-Man-NPs on M2 macrophage polarization, indicating the therapeutic potential of these β-cyclodextrin glycoconjugates in the treatment of inflammatory diseases and wound healing.

Antimicrobial Peptides: The Promising Therapeutics for Cutaneous Wound Healing

Chronic wound infections have caused an increasing number of deaths and economic burden, which necessitates wound treatment options. Hitherto, the development of functional wound dressings has achieved reasonable progress. Antibacterial agents, growth factors, and miRNAs are incorporated in different wound dressings to treat various types of wounds. As an effective antimicrobial agent and emerging wound healing therapeutic, antimicrobial peptides (AMPs) have attracted significant attention. The present study focuses on the application of AMPs in wound healing and discusses the types, properties and formulation strategies of AMPs used for wound healing. In addition, the clinical trial and the current status of studies on "antimicrobial peptides and wound healing" are elaborated through bibliometrics. Also, the challenges and opportunities for further development and utilization of AMP formulations in wound healing are discussed.

Cathelicidin-WA Protects Against LPS-Induced Gut Damage Through Enhancing Survival and Function of Intestinal Stem Cells

Preservation of intestinal stem cells (ISCs) plays a critical role in initiating epithelial regeneration after intestinal injury. Cathelicidin peptides have been shown to participate in regulating intestinal damage repair. However, it is not known how exactly Cathelicidin-WA (CWA) exert its function after tissue damage. Using a gut injury model in mice involving Lipopolysaccharide (LPS), we observed that CWA administration significantly improved intestinal barrier function, preserved ISCs survival, and augmented ISCs viability within the small intestine (SI) under LPS treatment. In addition, CWA administration effectively prevented proliferation stops and promoted the growth of isolated crypts. Mechanistically, our results show that the appearance of γH2AX was accompanied by weakened expression of SETDB1, a gene that has been reported to safeguard genome stability. Notably, we found that CWA significantly rescued the decreased expression of SETDB1 and reduced DNA damage after LPS treatment. Taken together, CWA could protect against LPS-induced gut damage through enhancing ISCs survival and function. Our results suggest that CWA may become an effective therapeutic regulator to treat intestinal diseases and infections.

Immunomodulatory Properties of Host Defence Peptides in Skin Wound Healing

Cutaneous wound healing is a vital biological process that aids skin regeneration upon injury. Wound healing failure results from persistent inflammatory conditions observed in diabetes, or autoimmune diseases like psoriasis. Chronic wounds are incurable due to factors like poor oxygenation, aberrant function of peripheral sensory nervature, inadequate nutrients and blood tissue supply. The most significant hallmark of chronic wounds is heavily aberrant immune skin function. The immune response in humans relies on a large network of signalling molecules and their interactions. Research studies have reported on the dual role of host defence peptides (HDPs), which are also often called antimicrobial peptides (AMPs). Their duality reflects their potential for acting as antibacterial peptides, and as immunodulators that assist in modulating several biological signalling pathways related to processes such as wound healing, autoimmune disease, and others. HDPs may differentially control gene regulation and alter the behaviour of epithelial and immune cells, resulting in modulation of immune responses. In this review, we shed light on the understanding and most recent advances related to molecular mechanisms and immune modulatory features of host defence peptides in human skin wound healing. Understanding their functional role in skin immunity may further inspire topical treatments for chronic wounds.

Hepatocyte growth factor ameliorates methylglyoxal-induced peritoneal inflammation and fibrosis in mouse model

BACKGROUND

Peritoneal dialysis (PD) is essential for patients with end-stage renal disease. Peritoneal fibrosis (PF) is a complex inflammatory, fibrogenic process. No effective treatments are available to prevent these processes. Hepatocyte growth factor (HGF) possesses anti-inflammatory and anti-fibrotic properties. The aim of this study was to analyze whether HGF suppresses MGO-induced peritoneal inflammation and fibrosis in a mouse model.

METHODS

PF was induced by intraperitoneal (IP) injections of MGO for 14 days. C57/BL/6 mice were divided into three groups: Sham group (only vehicle); Sham + MGO group (PF induced by MGO); and HGF + MGO group (PF mice treated with recombinant human-HGF). PF was assessed from tissue samples by Masson's trichrome staining. Inflammation and fibrosis-associated factors were assessed by immunohistochemistry and quantitative real-time PCR.

RESULTS

MGO-injected mice showed significant thickening of the submesothelial compact zone with PF. Treatment with HGF significantly reduced PM thickness and suppressed the expression of collagen I and III and α-SMA. Expression of profibrotic and proinflammatory cytokines (TGF-β, TNF-α, IL-1β) was reduced by HGF treatment. The number of macrophages, and M1 and M2 macrophage-related markers, such as CD86, CD206, and CD163, was reduced in HGF + MGO mice.

CONCLUSION

HGF attenuates MGO-induced PF in mice. Furthermore, HGF treatment reduces myofibroblast and macrophage infiltration, and attenuates the upregulated expression of proinflammatory and profibrotic genes in peritoneal tissues. HGF might be an effective approach to prevent the development of PF in patients undergoing PD.

Carbon Monoxide-Releasing Molecule-3 Regulates the Polarization of Lipopolysaccharide-Induced Macrophages

Macrophages show two main phenotypes, the M1-type (pro-inflammatory) and the M2-type (anti-inflammatory). The purpose of this research was to investigate the regulatory effect of carbon monoxide releasing molecule-3 (CORM-3) on LPS-induced macrophage polarization. LPS-induced RAW264.7 cells were exposed to CORM-3 for 24 h. Polarization of cells was checked by flow cytometry; expression of M1 or M2 macrophage-related factors and NF-κB signaling factors was examined by RT-PCR, ELISA, and Western blot. Male C57 mice were divided into three groups: normal group; periodontitis group, where experimental periodontitis was established in mice; LPS+CORM-3 group, where mice with experimental periodontitis were treated with CORM-3. Polarization of macrophages and the expression of M1 or M2 macrophage-related factors were detected by immunofluorescence, ELISA, and RT-PCR. CORM-3 significantly reduced M1 macrophage proportion, but increased M2 proportion in LPS-stimulated cells. Accordingly, CORM-3 significantly suppressed the expression of M1 macrophage-related TNF-α, iNOS, IL-1β, and IL-6, but promoted M2-related IL-10 and Arg-1. The expression of p-p65, p-p50, and p-IκB induced with LPS was inhibited by CORM-3. In vivo experiments indicated that CORM-3 induced more M2 macrophages in periodontal tissues in mice with experimental periodontitis. The expression of M1 macrophage-related factor in periodontitis was inhibited, but the expression of M2-related factors was increased by CORM-3. CORM-3 inhibits macrophage polarization to pro-inflammatory M1-type and promotes to anti-inflammatory M2-type, which provides scientific basis for the application of CORM-3 in the treatment of periodontitis.

Isolation, purification and identification of immunologically active peptides from Hericium erinaceus

Biologically active peptides released by proteins are important in regulating immunity. The purpose of this study was to isolate and purify an immunologically active peptide from Hericium erinaceus (H. erinaceus) and to explore its effect on cytokine secretion and differentiation of macrophages. An active peptide with an amino acid sequence, Lys-Ser-Pro-Leu-Tyr (KSPLY) was obtained from H. erinaceus protein by ultrafiltration combined with multistage chromatography separation and identification technology. Subsequently, it was confirmed that the synthetic peptide KSPLY had a good immunomodulatory activity at a concentration of 100 μmol/L and could promote the secretion of NO, IL-1β, IL-6 and TNF-α by macrophages. The effects of KSPLY on M1 macrophages and M2 macrophages were also studied. Results showed that KSPLY inhibited the secretion of NO and IL-6 by M1 macrophages and promoted the tendency of M2 macrophages to transform to M1 macrophages. Therefore, it can be concluded that KSPLY is an effective immunomodulatory peptide that may be beneficial in cancer treatment and human health improvement.

Curcumin prevents osteocyte apoptosis by inhibiting M1-type macrophage polarization in mice model of glucocorticoid-associated osteonecrosis of the femoral head

Inflammation is a contributing factor in osteocyte apoptosis, which is strongly associated with the development of glucocorticoid-associated osteonecrosis of the femoral head (GA-ONFH). Curcumin is a naturally derived drug that regulates immunity and inhibits inflammation. This study aimed to examine the capacity of curcumin to prevent osteocyte apoptosis and GA-ONFH, while elucidating possible mechanisms of action. C57/BL6 female mice were divided into control, GA-ONFH, and curcumin-treated GA-ONFH groups. We determined the effect of curcumin on the polarization of RAW264.7 and the apoptosis of MLO-Y4 cells. We found that curcumin reduced the infiltration of M1-type macrophages in the femoral heads and alleviated systemic inflammation in GA-ONFH models. Additionally, curcumin decreased the apoptosis of osteocytes in the femoral heads and the ratio of GA-ONFH in mice. Further, in vitro curcumin intervention inhibited M1-type polarization via the Janus kinase1/2-signal transducer and activator of transcription protein1 (JAK1/2-STAT1) pathway. Taken together, this study demonstrates that curcumin is effective in preventing osteocyte apoptosis and the development of GA-ONFH in a mouse model. Curcumin prevents inflammatory-mediated apoptosis of osteocytes in part through inhibition of M1 polarization through the JAK1/2-STAT1 pathway. These findings provide novel insights as well as a potential preventive agent for GA-ONFH. This article is protected by copyright. All rights reserved.

Cathelicidin Host Defense Peptides and Inflammatory Signaling: Striking a Balance

Host-defense peptides (HDPs) are vital components of innate immunity in all vertebrates. While their antibacterial activity toward bacterial cells was the original focus for research, their ability to modulate immune and inflammatory processes has emerged as one of their major functions in the host and as a promising approach from which to develop novel therapeutics targeting inflammation and innate immunity. In this review, with particular emphasis on the cathelicidin family of peptides, the roles of natural HDPs are examined in managing immune activation, cellular recruitment, cytokine responses, and inflammation in response to infection, as well as their contribution(s) to various inflammatory disorders and autoimmune diseases. Furthermore, we discuss current efforts to develop synthetic HDPs as therapeutics aimed at restoring balance to immune responses that are dysregulated and contribute to disease pathologies.

Cathelicidin Modulates Vascular Smooth Muscle Cell Phenotypic Switching through ROS/IL-6 Pathway

Vascular smooth muscle cells (VSMC) are stromal cells of the blood vessels and their differentiation is thought to be essential during atherosclerosis. Cathelicidin-related antimicrobial peptides (CRAMP) are suggested to play a role in the development of atherosclerosis. Even so, the relationship of CRAMP and VSMC remains unclear. The present study was to determine whether CRAMP regulates VSMC phenotypic transformation and underlying mechanisms. We demonstrated that CRAMP could reverse platelet-derived growth factor-BB (PDGF-BB)-induced VSMC phenotypic transformation, evidencing by increasing α-smooth muscle actin (α-SMA), smooth muscle 22α (SM22α) and decreasing of proliferation and migration. Further studies showed that CRAMP inhibited nuclear factor κB (NF-κB)-induced autocrine of interleukin-6 (IL-6), which further activated of janus kinase 2 (JAK2)/signal transducer and activator 3 (STAT3). Meanwhile, our data showed that CRAMP can significantly inhibit PDGF-BB enhanced intracellular reactive oxygen species (ROS) level which further affected the NF-κB signaling pathway, indicating that CRAMP can regulate the phenotypic transformation of VSMC by regulating oxidative stress. These results indicated that CRAMP regulated the differentiation of VSMC by inhibiting ROS-mediated IL-6 autocrine, suggesting that targeting CRAMP is a potential avenue for regulating the differentiation of VSMC and treatment of atherosclerosis.

Macrophages in Bone Homeostasis

Aberrant or prolonged immune responses has been proved to be involved in bone homeostasis. As a component of the innate immune system, macrophages play a critical role in bone homeostasis. Conventionally, according to response to the various panel of stimuli, macrophages can be plastically classified into two major phenotypes: M1 and M2. M1 macrophages are generally proinflammatory, whereas M2 are anti-inflammatory. Although studies demonstrated that both M1 and M2 phenotypes have been implicated in various inflammatory bone diseases, their direct role in bone homeostasis remains unclear. Thus, in this review, we briefly discuss the term "osteoimmunology", which deals with the crosstalk and shared mechanisms of the bone and immune systems. In addition, we overview M1 and M2 macrophages for their role in osteoclastogenesis and osteogenesis as well as relevant signaling cascades involved.

Topical antimicrobial peptide formulations for wound healing: Current developments and future prospects

Antimicrobial peptides (AMPs) are the natural antibiotics recognized for their potent antibacterial and wound healing properties. Bare AMPs have limited activity following topical application attributable to their susceptibility to environment (hydrolysis, oxidation, photolysis), and wound (alkaline pH, proteolysis) related factors as well as minimal residence time. Therefore, the formulation of AMPs is essential to enhance stability, prolong delivery, and optimize effectiveness at the wound site. Different topical formulations of AMPs have been developed so far including nanoparticles, hydrogels, creams, ointments, and wafers to aid in controlling bacterial infection and enhance wound healing process in vivo. Herein, an overview is provided of the AMPs and current understanding of their formulations for topical wound healing applications along with suitable examples. Furthermore, future prospects for the development of effective combination AMP formulations are discussed. STATEMENT OF SIGNIFICANCE: Chronic wound infection and subsequent development of antibiotic resistance are serious clinical problems affecting millions of people worldwide. Antimicrobial peptides (AMPs) possess great potential in effectively killing the bacteria with minimal risk of resistance development. However, AMPs susceptibility to degradation following topical application limits their antimicrobial and wound healing effects. Therefore, development of an optimized topical formulation with high peptide stability and sustained AMP delivery is necessary to maximize the antimicrobial and wound healing effects. The present review provides an overview of the state-of-art in the field of topical AMP formulations for wound healing. Current developments in the field of topical AMP formulations are reviewed and future prospects for the development of effective combination AMP formulations are discussed.

Bifidobacterium lactis BB-12 Attenuates Macrophage Aging Induced by D-Galactose and Promotes M2 Macrophage Polarization

Immunosenescence comprises a set of dynamic changes occurring in innate and adaptive immune systems, and macrophage aging plays an important role in innate and adaptive immunosenescence. However, function and polarization changes in aging macrophages have not been fully evaluated, and no effective method for delaying macrophage senescence is currently available. The results of this study reveal that D-galactose (D-gal) can promote J774A.1 macrophage senescence and induce macrophage M1 polarization differentiation. Bifidobacterium lactis BB-12 can significantly inhibit J774A.1 macrophage senescence induced by D-gal. IL-6 and IL-12 levels in the BB-12 groups remarkably decreased compared with that in the D-gal group, and the M2 marker, IL-10, and Arg-1 mRNA levels increased in the BB-12 group. BB-12 inhibited the expression of p-signal transducer and activator of transcription 1 (STAT1) and promoted p-STAT6 expression. In summary, the present study indicates that BB-12 can attenuate the J774A.1 macrophage senescence and induce M2 macrophage polarization, thereby indicating the potential of BB-12 to slow down immunosenescence and inflamm-aging.

Inulin alleviates inflammation of alcoholic liver disease via SCFAs-inducing suppression of M1 and facilitation of M2 macrophages in mice

BACKGROUND

Alcoholic liver disease (ALD) presents one of the leading causes of cirrhosis worldwide. We have demonstrated that inulin alleviates ALD in mice. However, the exact role of hepatic macrophages in effects of inulin on ALD remains largely unclear.

METHODS

In vivo, mice were divided into 4 groups: pair-fed (PF) group (PF/CON), alcohol-fed (AF) group (AF/CON), PF with inulin (INU) group (PF/INU) and AF with INU group (AF/INU). Each group was fed modified Lieber-DeCarli liquid diet with or without alcohol. In vitro, RAW264.7 cell lines were polarized to M1 macrophage (Mψ) or M2 Mψ subsets with lipopolysaccharide (LPS) or interleukin-4 (IL-4) stimulation, respectively. The effects of propionate, butyrate and valeric on macrophage M1/M2 were investigated.

RESULTS

The contents of propionate, butyrate and valeric were significantly increased in AF/INU group compared with that in the AF/CON group. M1 Mψ, inducible nitric oxide synthase (iNOS) and tumor necrosis factor-α (TNF-α) in AF/INU group were significantly lower than those in AF/CON group. In contrast, M2 Mψ, arginase-1 (Arg-1), and interleukin-10 (IL-10) were notably increased in AF/INU group. In vitro, sodium propionate, sodium butyrate and sodium valerate can suppress M1 Mψ and increase M2 Mψ polarization.

CONCLUSION

In ALD, inulin ameliorates the inflammation via SCFAs-inducing suppression of M1 and facilitation of M2 Mψ, which may potentially contribute to the control of the disease.

Antimicrobial peptide KR-32 alleviates Escherichia coli K88-induced fatty acid malabsorption by improving expression of fatty acid transporter protein 4 (FATP4)1

Bacterial infection causes nutrient malabsorption in small intestine. KR-32, a kind of synthetic antimicrobial peptide, has the bacteriostatic effect. In the present study, 2 experiments were designed to analyze the effects of KR-32 on fat absorption of piglets with or without Escherichia coli infection. In Exp. 1, 12 weaning piglets (21 d old) were allocated to 2 groups: piglets with an intraperitoneal (i.p.) injection of antimicrobial peptide KR-32 (APK) and piglets with an i.p. injection of an equivalent volume (1 mL) of phosphate-buffered saline (PBS) (CON-1). Results showed that after 7 d of growth, KR-32 did not significantly change growth performance and apparent total tract digestibility (ATTD) of feed nutrients of normal pigs. To confirm whether KR-32 affects those of enterotoxigenic Escherichia coli (ETEC) K88-challenged pigs, we performed Exp. 2, in which 18 piglets (28 d old) were divided into the following 3 groups: 1) piglets orally challenged with 1 × 1010 cfu ETEC K88 on day 1 followed by an i.p. injection of 0.6 mg/kg KR-32 (K88 + APK); 2) piglets orally challenged with 1 × 1010 cfu ETEC K88 on day 1 followed by an i.p. injection of an equivalent volume (1 mL) of PBS (K88); and 3) piglets with an oral administration of fresh Luria-Bertani broth (50 mL) followed by an i.p. injection of an equivalent volume of PBS (CON-2). Results showed that ETEC K88 challenge led to poor ADFI, ADG, and G:F in piglets; decreased ATTD of feed nutrients, especially CP and ether extract (EE); and intestinal morphology disorder. After i.p. injection of KR-32, ADG and ATTD of CP and EE were greatly increased, G:F was significantly reduced (P < 0.05), and, especially, ATTD of EE returned to a normal level compared with group CON-2. Fatty acid absorption also highly increased after KR-32 injection. Then we focused on fat digestion and fatty acid uptake. The pH in the intestine and pancreas lipase showed no difference among the 3 treatment groups, whereas fatty acid transporter protein 4 (FATP4) expression was remarkably improved (P < 0.05) and the epithelial barrier was recovered after i.p. injection of KR-32. In conclusion, KR-32, given to ETEC K88-challenged piglets, improved growth performance, ATTD of EE, fatty acid absorption, and intestinal morphology, which indicated that KR-32 was likely to improve the expression of FATP4 and by repairing the epithelial barrier, thereby alleviating fatty acid malabsorption.

Integrated Metabolomics and Network Pharmacology Study on Immunoregulation Mechanisms of Panax ginseng through Macrophages

Panax ginseng (PG) is a widely used functional food and herbal with immunoregulation activity. Currently, immunoregulation studies of PG mainly focused on the specific actions of individual constituents. However, the integral immunoregulation mechanisms of PG need further research. In this study, an integrated metabolomics and network pharmacology approach were used to investigate it. High-content screening was used to evaluate macrophage phagocytosis activity of PG. Untargeted metabolomics profiling of murine macrophage cells with UHPLC-Q-TOF-MS and a multivariate data method were performed to discover the potential biomarkers and metabolic pathways. Then, a macrophage phenotype related "ingredients-targets-metabolites" network of PG was constructed using network pharmacology for further research. As a result, PG can significantly enhance macrophage phagocytosis of GFP-E. coli. A total of twenty potential biomarkers and ten main pathways for which levels changed markedly upon treatment were identified, including glycerophospholipid metabolism, glutathione metabolism, choline metabolism, and taurine metabolism. Twenty compounds of PG associated with metabolomic changes were selected by the network pharmacology analysis, including ginsenoside Re, ginsenoside Rg1, frutinone A, and kaempferol. The network pharmacology results also showed that PG can polarize macrophages to both M1 and M2 phenotype but may be prone to M2 phenotype. In conclusion, our results indicated that PG may be prone to polarize macrophages to M2 phenotype by mainly regulating the glutathione and choline metabolism, which was related to twenty compounds of PG.

Cell wall mannoprotein of Candida albicans polarizes macrophages and affects proliferation and apoptosis through activation of the Akt signal pathway

Candida albicans is a commensal fungus that associates with human hosts. Under normal circumstances this interaction does not produce any severe life-threatening disease, as macrophages of the innate immune system will result in its clearance. However, disorders may arise in immunosuppressed individuals. To understand the bioactivity of Candida albicans cell wall polysaccharides, which represent an important component of its function, mannoprotein from this fungus was extracted, purified and analyzed. Mannoprotein with α-(1,2) and α-(1,6) linkages was investigated with use of HPLC and NMR. Co-incubation of mannoprotein with macrophages resulted in a mannoprotein with the potential to polarize macrophages to M1 and promote phagocytosis/microbial killing ability thus increasing the clearance of pathogens through Akt2. Moreover, mannoprotein within the cell wall promoted cell proliferation and inhibited apoptosis by activation of the Akt signaling pathway. Collectively, α-(1,6)(1,2)-mannoprotein, one of the five polysaccharides extracted from the cell wall of Candida albicans, demonstrates immune-enhancing effects by activation of the Akt signaling pathway. These findings provide important new insights into the biological effects of polysaccharides on macrophages. Such information can then serve as the foundation for the development of novel anti-fungal medications.

Overview of RAW264.7 for osteoclastogensis study: Phenotype and stimuli

Bone homeostasis is preserved by the balance of maintaining between the activity of osteogenesis and osteoclastogenesis. However, investigations for the osteoclastogenesis were hampered by considerable difficulties associated with isolating and culturing osteoclast in vivo. As the alternative, stimuli‐induced osteoclasts formation from RAW264.7 cells (RAW‐OCs) have gain its importance for extensively osteoclastogenic study of bone diseases, such as rheumatoid arthritis, osteoporosis, osteolysis and periodontitis. However, considering the RAW‐OCs have not yet been well‐characterized and RAW264.7 cells are polymorphic because of a diverse phenotype of the individual cells comprising this cell linage, and different fate associated with various stimuli contributions. Thus, in present study, we provide an overview for current knowledge of the phenotype of RAW264.7 cells, as well as the current understanding of the complicated interactions between various stimuli and RAW‐OCs in the light of the recent progress.

Cathelicidin-WA attenuates LPS-induced inflammation and redox imbalance through activation of AMPK signaling

Dysregulated activation of inflammation is associated with the development and progression of many diseases. Generation of reactive oxygen species (ROS) has been shown to promote an inflammatory response. Cathelicidin peptides not only defend against the invasion of various microbes but also play an important role in regulating immune responses. The objective of this study was to investigate the effects and mechanisms of Cathelicidin-WA (CWA) on the inflammatory response and oxidative stress in macrophages. Our results showed that CWA efficiently attenuated lipopolysaccharide (LPS)-stimulated inflammation and oxidative stress both in vivo and in vitro. Mechanistically, we found that CWA significantly reduced the LPS-induced nuclear translocation of NF-κB, thus decreasing the production of the pro-inflammatory cytokines TNF-α and IL-6 in macrophages. On the other hand, CWA markedly promoted the nuclear translocation of Nrf2 via the AKT pathway and p38 signaling. This resulted in increased expression of the anti-oxidative genes NQO-1 and HO-1 and alleviated oxidative stress in LPS-stimulated macrophages. Interestingly, the effects of CWA were diminished when AMPK was knocked down. Consistently, we noticed that CWA failed to ameliorate the LPS-induced inflammatory response and oxidative stress in AMPK knockout mice. Furthermore, we discovered that LKB1 was essential for AMPK activation by CWA. These data demonstrated for the first time that CWA attenuated LPS-stimulated inflammation and redox imbalance through regulating LKB1-AMPK signaling. Such knowledge provides new insights into the mechanisms through which Cathelicidin peptides modulate immune responses.

Antimicrobial Peptides and Their Therapeutic Potential for Bacterial Skin Infections and Wounds

Alarming data about increasing resistance to conventional antibiotics are reported, while at the same time the development of new antibiotics is stagnating. Skin and soft tissue infections (SSTIs) are mainly caused by the so called ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) which belong to the most recalcitrant bacteria and are resistant to almost all common antibiotics. S. aureus and P. aeruginosa are the most frequent pathogens isolated from chronic wounds and increasing resistance to topical antibiotics has become a major issue. Therefore, new treatment options are urgently needed. In recent years, research focused on the development of synthetic antimicrobial peptides (AMPs) with lower toxicity and improved activity compared to their endogenous counterparts. AMPs appear to be promising therapeutic options for the treatment of SSTIs and wounds as they show a broad spectrum of antimicrobial activity, low resistance rates and display pivotal immunomodulatory as well as wound healing promoting activities such as induction of cell migration and proliferation and angiogenesis. In this review, we evaluate the potential of AMPs for the treatment of bacterial SSTIs and wounds and provide an overview of the mechanisms of actions of AMPs that contribute to combat skin infections and to improve wound healing. Bacteria growing in biofilms are more resistant to conventional antibiotics than their planktonic counterparts due to limited biofilm penetration and distinct metabolic and physiological functions, and often result in chronification of infections and wounds. Thus, we further discuss the feasibility of AMPs as anti-biofilm agents. Finally, we highlight perspectives for future therapies and which issues remain to bring AMPs successfully to the market.