M1 to M2 macrophage polarization in heparin-binding epidermal growth factor-like growth factor therapy for necrotizing enterocolitis

1,25-dihydroxyvitamin D3 augments low-dose PMA-based monocyte-to-macrophage differentiation in THP-1 cells

The human monocytic THP-1 cell line is the most routinely employed in vitro model for studying monocyte-to-macrophage differentiation. Despite the wide use of this model, differentiation protocols using phorbol 12-myristate-13-acetate (PMA) or 1,25-dihydroxyvitamin D3 (1,25D3) vary drastically between studies. Given that differences in differentiation protocols have the potential to impact the characteristics of the macrophages produced, we aimed to assess the efficacy of three different THP-1 differentiation protocols by assessing changes in morphology and gene- and cell surface macrophage marker expression. THP-1 cells were differentiated with either 5 nM PMA, 10 nM 1,25D3, or a combination thereof, followed by a rest period. The results indicated that all three protocols significantly increased the expression of the macrophage markers, CD11b (p < 0.001) and CD14 (p < 0.010). Despite this, THP-1 cells exposed to 1,25D3 alone did not adopt the morphological and expression characteristics associated with macrophages. PMA was required to produce these characteristics, which were found to be more pronounced in the presence of 1,25D3. Both PMA- and PMA with 1,25D3-differentiated THP-1 cells were capable of M1 and M2 macrophage polarization, though the gene expression of polarization-associated markers was most pronounced in PMA with 1,25D3-differentiated THP-1 cells. Moreover, the combination of PMA with 1,25D3 appeared to support the process of commitment to a particular polarization state.

RNF31-mediated IKKα ubiquitination aggravates inflammation and intestinal injury through regulating NF-κB activation in human and mouse neonates

AIMS

Neonatal necrotizing enterocolitis (NEC) is a leading cause of intestine inflammatory disease, and macrophage is significantly activated during NEC development. Posttranslational modifications (PTMs) of proteins, particularly ubiquitination, play critical roles in immune response. This study aimed to investigate the effects of ubiquitin-modified proteins on macrophage activation and NEC, and discover novel NEC-related inflammatory proteins.

MATERIALS AND METHODS

Proteomic and ubiquitin proteomic analyses of intestinal macrophages in NEC/healthy mouse pups were carried out. In vitro macrophage inflammation model and in vivo NEC mouse model, as well as clinical human samples were used for further verification the inhibitor of nuclear factor-κB kinase α (IKKα) ubiquitination on NEC development through Western blot, immunofluorescence, quantitative real-time polymerase chain reaction (qRT-PCR) and flow cytometry.

KEY FINDINGS

We report here that IKKα was a new ubiquitin-modified protein during NEC through ubiquitin proteomics, and RING finger protein 31 (RNF31) acted as an E3 ligase to be involved in IKKα degradation. Inhibition of IKKα ubiquitination and degradation with siRNF31 or proteasome inhibitor decreased nuclear factor-κB (NF-κB) activation, thereby decreasing the expression of pro-inflammatory factors and M1 macrophage polarization, resulting in reliving the severity of NEC.

SIGNIFICANCE

Our study suggests the activation of RNF31-IKKα-NF-κB axis triggering NEC development and suppressing RNF31-mediated IKKα degradation may be therapeutic strategies to be developed for NEC treatment.

Oral alginate microspheres for the efficient site-specific delivery of epidermal growth factor attenuated murine ulcerative colitis via repairing the mucosal barrier

Ulcerative colitis (UC) is a chronic bowel inflammatory disease affecting the colorectum. Epidermal growth factor (EGF) has been demonstrated to be effective to counteract UC. However, there exists the gastrointestinal challenges such as stomach acid, enzyme and bile salts for oral delivery of EGF. Herein, calcium alginate microsphere was prepared by the microfluidic technique to encapsulate EGF. The morphology of EGF-loaded microsphere (MS-EGF) was spherical and its average particle size was 80 ± 23 μm. The encapsulation efficiency of EGF was reaching to 93.8 % ± 1.6 %. In vitro release experiments showed that MS-EGF presented the good pH-sensitive properties, that was, it could effectively resist the gastric acid and small intestinal fluids, and undergone the rapid dissolution in the artificial colon fluid. In vitro cellular experiments demonstrated that the bioactivity of EGF was well preserved by microsphere. Moreover, in vivo murine colitis model showed that MS-EGF presented the obvious colitis alleviation. Furthermore, the colonic morphology of colitis mice was effectively recovered and the tight junction between the gut epithelium was obviously repaired. In conclusion, calcium alginate microsphere might be a promising vehicle of EGF for UC treatment.

Immunomodulatory Effect of Cordyceps militaris Polysaccharide on RAW 264.7 Macrophages by Regulating MAPK Signaling Pathways

Polysaccharide is one of the principal bioactive components found in medicinal mushrooms and has been proven to enhance host immunity. However, the possible mechanism of immunomodulatory activity of Cordyceps militaris polysaccharide is not fully understood. Hot water extraction and alcohol precipitation, DEAE-Sephadex A-25 chromatography, and Sephadex G-100 chromatography were used to isolate polysaccharide from C. militaris. A high-molecular-weight polysaccharide isolated from C. militaris was designated as HCMP, which had an Mw of 6.18 × 105 Da and was composed of arabinose, galactose, glucose, mannose, and xylose in a mole ratio of 2.00:8.01:72.54:15.98:1.02. The polysaccharide content of HCMP was 91.2% ± 0.16. The test in vitro showed that HCMP activated mouse macrophage RAW 264.7 cells by enhancing phagocytosis and NO production, and by regulating mRNA expressions of inflammation-related molecules in RAW 264.7 cells. Western blotting revealed that HCMP induced the phosphorylation of mitogen-activated protein kinases (MAPKs). Moreover, using inhibitors of MAPKs decreased the mRNA levels of inflammation-related molecules induced by HCMP. These data evidenced that the immunomodulatory effect of HCMP on RAW 264.7 macrophages was mediated via the MAPK signaling pathway. These findings suggested that HCMP could be developed as a potent immunomodulatory agent for use in functional foods and dietary supplements.

Progranulin mitigates intestinal injury in a murine model of necrotizing enterocolitis by suppressing M1 macrophage polarization

Neonatal necrotizing enterocolitis (NEC) is a critical digestive disorder frequently affecting premature infants. Characterized by intestinal inflammation caused by activated M1 macrophages, modulation of macrophage polarization is considered a promising therapeutic strategy for NEC. It has been demonstrated that the growth factor-like protein progranulin (PGRN), which plays roles in a number of physiological and pathological processes, can influence macrophage polarization and exhibit anti-inflammatory characteristics in a number of illnesses. However, its role in NEC is yet to be investigated. Our research showed that the levels of PGRN were markedly elevated in both human and animal models of NEC. PGRN deletion in mice worsens NEC by encouraging M1 polarization of macrophages and escalating intestinal damage and inflammation. Intravenous administration of recombinant PGRN to NEC mice showed significant survival benefits and protective effects, likely due to PGRN's ability to inhibit M1 polarization and reduce the release of pro-inflammatory factors. Our findings shed new light on PGRN's biological role in NEC and demonstrate its potential as a therapeutic target for the disease.

Fibroblast growth factor signaling in macrophage polarization: impact on health and diseases

Fibroblast growth factors (FGFs) are a versatile family of peptide growth factors that are involved in various biological functions, including cell growth and differentiation, embryonic development, angiogenesis, and metabolism. Abnormal FGF/FGF receptor (FGFR) signaling has been implicated in the pathogenesis of multiple diseases such as cancer, metabolic diseases, and inflammatory diseases. It is worth noting that macrophage polarization, which involves distinct functional phenotypes, plays a crucial role in tissue repair, homeostasis maintenance, and immune responses. Recent evidence suggests that FGF/FGFR signaling closely participates in the polarization of macrophages, indicating that they could be potential targets for therapeutic manipulation of diseases associated with dysfunctional macrophages. In this article, we provide an overview of the structure, function, and downstream regulatory pathways of FGFs, as well as crosstalk between FGF signaling and macrophage polarization. Additionally, we summarize the potential application of harnessing FGF signaling to modulate macrophage polarization.

Harnessing anti-inflammatory pathways and macrophage nano delivery to treat inflammatory and fibrotic disorders

Targeting specific organs and cell types using nanotechnology and sophisticated delivery methods has been at the forefront of applicative biomedical sciences lately. Macrophages are an appealing target for immunomodulation by nanodelivery as they are heavily involved in various aspects of many diseases and are highly plastic in their nature. Their continuum of functional "polarization" states has been a research focus for many years yielding a profound understanding of various aspects of these cells. The ability of monocyte-derived macrophages to metamorphose from pro-inflammatory to reparative and consequently to pro-resolving effectors has raised significant interest in its therapeutic potential. Here, we briefly survey macrophages' ontogeny and various polarization phenotypes, highlighting their function in the inflammation-resolution shift. We review their inducing mediators, signaling pathways, and biological programs with emphasis on the nucleic acid sensing-IFN-I axis. We also portray the polarization spectrum of macrophages and the characteristics of their transition between different subtypes. Finally, we highlighted different current drug delivery methods for targeting macrophages with emphasis on nanotargeting that might lead to breakthroughs in the treatment of wound healing, bone regeneration, autoimmune, and fibrotic diseases.

EGF-conditioned M1 macrophages Convey reduced inflammation into corneal endothelial cells through exosomes

Epidermal Growth Factor (EGF), a protein pivotal in cell proliferation and survival, has recently shown promise in alleviating inflammation. This study investigates EGF's impact on M1 macrophages, exploring its potential for anti-inflammatory and anti-vasculogenic interactions with corneal endothelial cells (CECs). Polarized M1 macrophages treated with EGF exhibited a suppression of gene expressions related to inflammatory and vasculogenic signals. The anti-inflammatory effects of EGF were observed in co-culture systems with human CECs (HCECs), showcasing its ability to alter macrophage phenotypes. Exosomes derived from EGF-treated M1 macrophages demonstrated enriched proteomic profiles related to immune system regulation and inflammation inhibition. When applied as eye drops in murine corneas, EGF-conditioned M1 macrophage-derived exosomes effectively reduced inflammation and increased M2-related ARG1 expression. This study highlights EGF's potential in mitigating inflammation in M1 macrophages and its delivery through exosomes to cultured HCECs and murine corneas, suggesting a novel therapeutic avenue for ocular surface anti-inflammatory treatments.

Honokiol prevents lung metastasis of triple-negative breast cancer by regulating polarization and recruitment of macrophages

Metastasis is the leading cause of breast cancer-associated death. Lung metastasis commonly occurs in triple-negative breast cancer (TNBC) metastasis, worsening the TNBC prognosis. Considering their role in tumor progression and metastasis, tumor-associated macrophages (TAMs) are essential therapeutic targets in cancer therapy. Previous studies have demonstrated that honokiol inhibits tumor growth and progression. Here we assessed how honokiol inhibits lung metastasis of TNBC by regulating the polarization of macrophages. We found that honokiol decreased the expression of IL-13-triggered M2 markers like CD206, Arg1, and CCL2, preventing the invasion and migration ability of TNBC cells. The activation of signal transducer and activator of transcription STAT6 and STAT3 was significantly suppressed by honokiol in M2 polarized macrophages. Meanwhile, honokiol increased the expression of LPS/IFNγ-induced M1 markers such as CD11c, iNOS, and IL12 by promoting STAT1 phosphorylation. Besides, honokiol decreased both the ratio of M2/M1 macrophages and the expression of the IL-10/IL-12 gene in lung tissues, thereby inhibiting the proliferation and metastasis of murine breast cancer. Moreover, honokiol reduced the infiltration of macrophages to the lung tissue through the CCL2/CCR2 pathways. These results highlight the potential of honokiol in suppressing TNBC tumor progression and lung metastasis by regulating the polarization and recruitment of macrophages.

Human milk-derived MANF, as an immuno-nutritional factor, maintains the intestinal epithelial barrier and protects against necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a leading cause of death in preterm infants. Compared to formula milk, breastfeeding protects against NEC. However, the composition of breast milk is quite complicated, and many immunological compositions remain unknown. In this study, we aimed to investigate the concentration of a secreted protein, Mesencephalic astrocyte-derived neurotrophic factor (MANF), in breastmilk and evaluate its immune-regulatory function in protecting the intestinal epithelial barrier. Our data indicated that MANF was secreted in human milk but could not be detected in infant formulas. More importantly, the amount of MANF in colostrum was higher than that in mature milk. We also clarified that MANF was mainly expressed in intestinal macrophages and was capable of inducing apoptosis and decreasing the inflammation of pro-inflammatory macrophages in both NEC intestinal tissues and BMDMs. Mechanismly, MANF protein significantly inhibited the apoptosis of intestinal epithelial cells and protected epithelial tight junctions through downregulation of the NF-κB pathway in pro-inflammatory macrophages. These results reveal the crucial function of human milk-derived MANF in intestinal macrophages, which contributes to downregulating the intestinal inflammatory response and protecting the homeostasis of intestinal epithelial cells. Our study not only demonstrates a potential mechanism underlying breastfeeding protective effects in NEC but also, more importantly, enables clinical translation, facilitating new strategies for the development of nutritional interventions in the prevention of NEC.

Transcriptomic analysis identifies lactoferrin-induced quiescent circuits in neonatal macrophages

Introduction

Upon birth, a hitherto naïve immune system is confronted with a plethora of microbial antigens due to intestinal bacterial colonization. To prevent excessive inflammation and disruption of the epithelial barrier, physiological mechanisms must promote immune-anergy within the neonatal gut. As high concentrations of human lactoferrin (hLF), a transferrin glycoprotein shown to modulate macrophage function, are frequently encountered in colostrum, its direct interaction with intestinal macrophages may satisfy this physiological need. Thus, the primary objective of this study was to investigate transcriptional changes induced by human lactoferrin in neonatal monocyte-derived macrophages.

Methods

Cord blood-derived monocytes were differentiated with M-CSF in presence or absence of 500 µg/mL hLF for 7 days and afterwards stimulated with 1 ng/mL LPS or left untreated. RNA was then isolated and subjected to microarray analysis.

Results

Differentiation of cord blood-derived monocytes in presence of hLF induced a distinct transcriptional program defined by cell cycle arrest in the G2/M phase, induction of IL-4/IL-13-like signaling, altered extracellular matrix interaction, and enhanced propensity for cell-cell interaction. Moreover, near-complete abrogation of transcriptional changes induced by TLR4 engagement with LPS was observed in hLF-treated samples.

Discussion

The global transition towards an M2-like homeostatic phenotype and the acquisition of quiescence elegantly demonstrate the ontogenetical relevance of hLF in attenuating pro-inflammatory signaling within the developing neonatal intestine. The marked anergy towards proinflammatory stimuli such as LPS further underlines the glycoprotein's potential therapeutic relevance.

New insights into intestinal macrophages in necrotizing enterocolitis: the multi-functional role and promising therapeutic application

Necrotizing enterocolitis (NEC) is an inflammatory intestinal disease that profoundly affects preterm infants. Currently, the pathogenesis of NEC remains controversial, resulting in limited treatment strategies. The preterm infants are thought to be susceptible to gut inflammatory disorders because of their immature immune system. In early life, intestinal macrophages (IMφs), crucial components of innate immunity, demonstrate functional plasticity and diversity in intestinal development, resistance to pathogens, maintenance of the intestinal barrier, and regulation of gut microbiota. When the stimulations of environmental, dietary, and bacterial factors interrupt the homeostatic processes of IMφs, they will lead to intestinal disease, such as NEC. This review focuses on the IMφs related pathogenesis in NEC, discusses the multi-functional roles and relevant molecular mechanisms of IMφs in preterm infants, and explores promising therapeutic application for NEC.

Interfering with Rac1-activation during neonatal monocyte-macrophage differentiation influences the inflammatory responses of M1 macrophages

Necrotizing enterocolitis (NEC) is a life-threatening, inflammatory disease affecting premature infants with intestinal necrosis, but the mechanism remains unclear. Neonatal macrophages are thought to play an important role in the pathogenesis of NEC through the production of proinflammatory cytokines. Restriction of cytokine expression in macrophages of NEC tissues may be beneficial. In adult macrophages, interfering with Rac1 has been shown to influence the expression of cytokines. Here, we investigated whether interfering with Rac1 in neonatal macrophages affects their inflammatory responses. First, we found that Rac1-activation was upregulated in the macrophages of rats with NEC model induction compared to controls. The M1 macrophages derived from human neonatal monocytes showed greater Rac1-activation than the M2 macrophages derived from the same monocytes. Inhibition of Rac1-activation by NSC23766 potently reduced the production of proinflammatory cytokines in these M1 macrophages. While neonatal monocytes differentiated into M1 macrophages in vitro, NSC23766 significantly altered cell function during the first six days of incubation with GM-CSF rather than during the subsequent stimulation phase. However, the same effect of NSC23766 was not observed in adult macrophages. Using mass spectrometry, Y-box binding protein 1 (YB1) was identified as being downregulated upon inhibition of Rac1-activation in the neonatal macrophages. Moreover, we found that inhibition of Rac1-activation shortens the poly A tail of PABPC1 mRNA, thereby reducing the translation of PABPC1 mRNA. Consequently, the downregulation of PABPC1 resulted in a reduced translation of YB1 mRNA. Furthermore, we found that TLR4 expression was downregulated in neonatal macrophages, while YB1 expression was reduced. Adding resatorvid (TLR4 signaling inhibitor) to the macrophages treated with NSC23766 did not further reduce the cytokine expression. These findings reveal a novel Rac1-mediated pathway to inhibit cytokine expression in neonatal M1 macrophages and suggest potential targets for the prevention or treatment of NEC.

Reduction of absolute monocyte counts is associated with the severity of preterm necrotizing enterocolitis

OBJECTIVE

Necrotizing enterocolitis (NEC) is characterized by a rich infiltration of macrophages in the intestines, which is derived from monocytes in the blood. The authors aimed to explore the changing trend of absolute monocyte counts (AMC) over time in NEC infants and to verify whether the reduction of AMC correlates with the severity of NEC and whether it can be used to identify infants who need surgery.

METHOD

The authors collected the clinical data of 66 control and 222 NEC infants. The NEC infants were divided into medical NEC (M-NEC) and surgical NEC (S-NEC). The counting of monocyte and their percentage change were compared at the time of birth, before NEC (baseline), the onset of NEC and after NEC (recovery). In addition, the same comparison was made among stages 1, 2 and 3 of Bell's staging, respectively.

RESULTS

The authors found that the AMC in NEC infants decreased sharply at the onset. Further comparison was made between 172 cases of M-NEC and 50 cases of S-NEC. It was discovered that the AMC reduced more in S-NEC infants at onset, but it increased more at recovery. In addition, the authors found that among stage 1,2 and 3, stage 3 had the lowest AMC and the largest percentage decrease at the onset.

CONCLUSION

The AMC decreases sharply in NEC infants at onset, and the degree of decline is associated with the severity of NEC. AMC is expected to be a marker of NEC and provide a reference for clinicians in the diagnosis and treatment of NEC.

Valorization of coffee bean processing waste for the sustainable extraction of biologically active pectin

The dry method of coffee processing generates a significant amount of coffee husk, an agricultural waste for which currently there is a lack of profitable use, and their disposal constitutes a major environmental problem. Pectin was extracted from coffee husk using citric acid solution (pH 1.5) by microwave-assisted extraction method, followed by using ice-cold ethanol. The coffee husk pectin (CHP) with a yield of 40.2% was characterized using SEM, FT-IR, and XRD techniques. The CHP exhibited significant in-vitro antioxidant activity as measured by using 2,2-diphenyl-1-picrylhydrazyl; (IC50 value of 395.1 ± 0.42 μg/mL), ferrous reducing antioxidant capacity (A700 nm = 0.55 ± 0.08), 2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging (42.02 ± 0.38%) and ascorbic acid auto-oxidation inhibition (92.01 ± 0.28%) assays. CHP demonstrated antibacterial activity against Escherichia coli and Bacillus cereus with an inhibition diameter of 20 ± 1.01 mm and 18 ± 0.84 mm, respectively. Interestingly, CHP showed a significant anti-inflammatory effect by negatively modulating the expressions of TNF-α and TGF- β in LPS-stimulated macrophage cell lines. Collectively, our findings suggest that the coffee husk is a potential source of commercial pectin, microwave-assisted extraction has a great potency on the commercial pectin extraction from the coffee husk and CHP demonstrates significant biological activity.

NAMPT inhibition relieves intestinal inflammation by regulating macrophage activation in experimental necrotizing enterocolitis

Nicotinamide phosphoribosyl transferase (NAMPT) is associated with various NAD+ -consuming enzymatic reactions. The precise role in intestinal mucosal immunity in necrotizing enterocolitis (NEC) is not well defined. Here, we examined whether NAMPT inhibition by the highly specific inhibitor FK866 could alleviate intestinal inflammation during the pathogenesis of NEC. In the present study, we showed that NAMPT expression was upregulated in the human terminal ileum of human infants with NEC. FK866 administration attenuated M1 macrophage polarization and relieved the symptoms of experimental NEC pups. FK866 inhibited intercellular NAD+ levels, macrophage M1 polarization, and the expression of NAD+ -dependent enzymes, such as poly (ADP ribose) polymerase 1 (PARP1) and Sirt6. Consistently, the capacity of macrophages to phagocytose zymosan particles, as well as antibacterial activity, were impaired by FK866, whereas NMN supplementation to restore NAD+ levels reversed the changes in phagocytosis and antibacterial activity. In conclusion, FK866 reduced intestinal macrophage infiltration and skewed macrophage polarization, which is implicated in intestinal mucosal immunity, thereby promoting the survival of NEC pups.

Hyaluronic acid modified oral drug delivery system with mucoadhesiveness and macrophage-targeting for colitis treatment

Based on the biocompatibility and macrophage targeting of natural polysaccharides, combined with the physiological and pathological characteristics of the gastrointestinal tract and colonic mucosa of ulcerative colitis (UC), we prepare dexamethasone (Dex)-loaded oral colon-targeted nano-in-micro drug delivery systems coated with multilayers of chitosan (CS), hyaluronic acid (HA), and finally Eudragit S100 (ECHCD MPs) using a layer-by-layer coating technique for UC treatment through regulating the M1/M2 polarization of intestinal macrophages. HA/CS/Dex nanoparticles (HCD NPs) are ingested by macrophages via CD44 receptor-mediated endocytosis to regulate M1-to-M2 macrophage polarization and exert anti-inflammatory effects. Moreover, ECHCD MPs show better colon-targeting properties than Dex-loaded chitosan nanoparticles (CD NPs) and HCD NPs which is demonstrated by stronger mucoadhesion to inflamed colon tissues. After oral administration, ECHCD MPs exert significant anti-UC effects. Therefore, ECHCD MPs are proven to be as promising oral colon-targeting drug delivery systems for Dex and have potential application in UC treatment.

Restoration of dysregulated intestinal barrier and inflammatory regulation through synergistically ameliorating hypoxia and scavenging reactive oxygen species using ceria nanozymes in ulcerative colitis

BACKGROUND

Reactive oxygen species (ROS) overproduction and excessive hypoxia play pivotal roles in the initiation and progression of ulcerative colitis (UC). Synergistic ROS scavenging and generating O₂ could be a promising strategy for UC treatment.

METHODS

Ceria nanozymes (PEG-CNPs) are fabricated using a modified reverse micelle method. We investigate hypoxia attenuating and ROS scavenging of PEG-CNPs in intestinal epithelial cells and RAW 264.7 macrophages and their effects on pro-inflammatory macrophages activation. Subsequently, we investigate the biodistribution, pharmacokinetic properties and long-term toxicity of PEG-CNPs in mice. PEG-CNPs are administered intravenously to mice with 2,4,6-trinitrobenzenesulfonic acid-induced colitis to test their colonic tissue targeting and assess their anti-inflammatory activity and mucosal healing properties in UC.

RESULTS

PEG-CNPs exhibit multi-enzymatic activity that can scavenge ROS and generate O₂, promote intestinal epithelial cell healing and inhibit pro-inflammatory macrophage activation, and have good biocompatibility. After intravenous administration of PEG-CNPs to colitis mice, they can enrich at the site of colonic inflammation, and reduce hypoxia-induced factor-1α expression in intestinal epithelial cells by scavenging ROS to generate O₂, thus further promoting disrupted intestinal mucosal barrier restoration. Meanwhile, PEG-CNPs can effectively scavenge ROS in impaired colon tissues and relieve colonic macrophage hypoxia to suppress the pro-inflammatory macrophages activation, thereby preventing UC occurrence and development.

CONCLUSION

This study has provided a paradigm to utilize metallic nanozymes, and suggests that further materials engineering investigations could yield a facile method based on the pathological characteristics of UC for clinically managing UC.

Macrophage Polarization: An Important Candidate Regulator for Lung Diseases

Macrophages are crucial components of the immune system and play a critical role in the initial defense against pathogens. They are highly heterogeneous and plastic and can be polarized into classically activated macrophages (M1) or selectively activated macrophages (M2) in response to local microenvironments. Macrophage polarization involves the regulation of multiple signaling pathways and transcription factors. Here, we focused on the origin of macrophages, the phenotype and polarization of macrophages, as well as the signaling pathways associated with macrophage polarization. We also highlighted the role of macrophage polarization in lung diseases. We intend to enhance the understanding of the functions and immunomodulatory features of macrophages. Based on our review, we believe that targeting macrophage phenotypes is a viable and promising strategy for treating lung diseases.

CCL3 aggravates intestinal damage in NEC by promoting macrophage chemotaxis and M1 macrophage polarization

BACKGROUND

NEC is a life-threatening gastrointestinal disease in neonates, the pathogenesis of which remains poorly understood.

METHODS

CCL3 levels in intestinal tissue of mice were measured and analyzed. HE staining was used to assess pathological changes in intestinal tissue. FCM was used to detect the proportion and phenotype of macrophages. RNA-seq and RT-PCR were used to evaluate the effect of CCL3 on macrophages.

RESULTS

CCL3 was highly expressed in the intestinal tissues of mice with NEC and induced macrophage infiltration. Transcriptome data showed that CCL3 strongly induced a transition in the phenotype of macrophages into a proinflammatory one. Mechanistically, in vivo experiments confirmed that CCL3 induced M1 macrophage polarization in NEC intestinal tissue, thereby aggravating inflammatory injury of intestinal tissue, which was alleviated by anti-CCL3 treatment. In addition, in vitro experiments showed that CCL3 significantly enhances the expression of M1-related genes in both PMφ and BMDM while inhibiting the expression of M2-related genes, which was also alleviated by anti-CCl3 treatment.

CONCLUSIONS

Our data elucidated the involvement of CCL3 in the pathogenesis of NEC, in which upregulated CCL3 expression exacerbated inflammatory intestinal damage by regulating macrophage chemotaxis and M1 phenotype polarization, suggesting that blocking CCL3 may be a potential strategy for effective intervention in NEC.

IMPACT

Our study represents an important conceptual advancement that CCL3 may be one of the key culprits of intestinal tissue damage in patients with NEC. CCL3 aggravates inflammatory intestinal injury and intestinal mucosal barrier imbalance by regulating the chemotaxis, polarization, and function of macrophages. Blocking CCL3 significantly reduced NEC-mediated intestinal injury, suggesting a new potential therapeutic strategy.

Heparin binding epidermal growth factor-like growth factor is a prognostic marker correlated with levels of macrophages infiltrated in lung adenocarcinoma

Background

The interactions between tumor cells and the host immune system play a crucial role in lung cancer progression and resistance to treatment. The alterations of EGFR signaling have the potential to produce an ineffective tumor-associated immune microenvironment by upregulating a series of immune suppressors, including inhibitory immune checkpoints, immunosuppressive cells, and cytokines. Elevated Heparin-binding EGF-like growth factor (HB-EGF) expression, one EGFR ligand correlated with higher histology grading, worse patient prognosis, and lower overall survival rate, acts as a chemotactic factor. However, the role of heparin-binding epidermal growth factor-like growth factor (HB-EGF) in the accumulation of immune cells in the tumor microenvironment remains unclear.

Methods

The clinical association of HB-EGF expression in lung cancer was examined using the Gene Expression Omnibus (GEO) repository. HB-EGF expression in different cell types was determined using single-cell RNA sequencing (scRNA-seq) dataset. The correlation between HB-EGF expression and cancer-immune infiltrated cells was investigated by performing TIMER and ClueGo pathways analysis from TCGA database. The chemotaxis of HB-EGF and macrophage infiltration was investigated using migration and immunohistochemical staining.

Results

The high HB-EGF expression was significantly correlated with poor overall survival in patients with lung adenocarcinoma (LUAD) but not lung squamous cell carcinoma (LUSC). Moreover, HB-EGF expression was correlated with the infiltration of monocytes, macrophages, neutrophils, and dendritic cells in LUAD but not in LUSC. Analysis of scRNA-seq data revealed high HB-EGF expression in lung cancer cells and myeloid cells. Results from the pathway analysis and cell-based experiment indicated that elevated HB-EGF expression was associated with the presence of macrophage and lung cancer cell migration. HB-EGF was highly expressed in tumors and correlated with M2 macrophage infiltration in LUAD.

Conclusions

HB-EGF is a potential prognostic marker and therapeutic target for lung cancer progression, particularly in LUAD.

NF-κB inactivation attenuates the M1 macrophage polarization in experimental necrotizing enterocolitis by glutaredoxin-1 deficiency

The pathogenesis of necrotizing enterocolitis (NEC) is severe inflammatory injury in preterm infants, which resulted from macrophage polarization. Nuclear factor-κB (NF-κB) is implicated to be involved in macrophage polarization. We here evaluated the essential role of NF-κB in macrophage polarization in NEC in human samples from neonates with NEC and the mouse experimental NEC model. Enhanced intestinal macrophage (IM) infiltration was presented in human neonates with NEC, the majority of which were M1 macrophages. Meanwhile, NF-κB was activated in the IMs in human NEC samples. NF-κB inhibition by BAY promoted the M1 to M2 macrophage polarization. Furthermore, glutaredoxin-1 (Grx1) deficiency promoted M2 polarization via NF-κB inactivation from the lipopolysaccharide-induced proinflammatory macrophages. The IMs isolated from Grx1^{- / -} mice presented with decreases in total numbers and less macrophage differentiation. Grx1^{- / -} derived IM were effective in the increased survival in experimental NEC through inflammation blocking. Our study provides evidence that NF-κB inactivation by Grx1 depletion contributed to the alleviation of NEC via inhibiting M1 macrophage polarization. The modulation to alternative macrophages in the intestines may provide a promising benefits for NEC treatment.

Peripheral and intestinal mucosal-associated invariant T cells in premature infants with necrotizing enterocolitis

Background: Necrotizing enterocolitis (NEC) is a potentially fatal inflammatory gastrointestinal disease in preterm infants with unknown pathogenesis. Mucosal-associated invariant T (MAIT) cells primarily accumulate at sites where exposure to microbes is ubiquitous and regulate immunological responses. As the implications of these cells in NEC development in premature infants remain unknown, we investigated the role and characteristics of MAIT cells in NEC pathogenesis.

Methods: The percentage of different MAIT cell subsets in peripheral blood samples of 30 preterm infants with NEC and 22 control subjects was estimated using flow cytometry. The frequency of MAIT cells in the intestinal tissues of five NEC patients and five control subjects was also examined. The level of serum cytokines was estimated using cytometric bead array. Potential associations between the different measurements were analyzed using the Spearman’s correlation test.

Results: Compared with controls, the NEC patients were found to have significantly reduced percentages of circulating CD161⁺ CD3⁺ CD8αα⁺ T cells and CD161⁺ CD3⁺ TCRγδ^-TCRVa7.2⁺ MAIT cells. In the intestinal tissues, the percentage of MAIT cells was significantly higher in samples from the NEC patients than the controls. Furthermore, the percentage of circulating MAIT cells in the peripheral blood samples was inversely correlated with that in the intestinal tissues of the NEC patients. The percentage of CD8αα⁺ MAIT cells was found to be significantly reduced in both peripheral blood and intestinal tissues of NEC patients. Following treatment, the frequency of circulating MAIT cells significantly increased in NEC patients and reached a level similar to that in the control subjects. However, there was no difference in the percentage of circulating CD8αα⁺ MAIT cells before and after treatment in the NEC patients.

Conclusion: Our results suggested that during the development of NEC MAIT cells accumulate in the inflammatory intestinal tissues, while the percentage of CD8aa⁺ MAIT cells is significantly decreased, which may lead to the dysfunction of MAIT cells in gut immunity.

ADAM17-mediated EGFR ligand shedding directs macrophage promoted cancer cell invasion

Macrophages in the tumor microenvironment have a significant impact on tumor progression. Depending on the signaling environment in the tumor, macrophages can either support or constrain tumor progression. It is therefore of therapeutic interest to identify the tumor-derived factors that control macrophage education. With this aim, we correlated the expression of ADAM proteases, which are key mediators of cell-cell signaling, to the expression of pro-tumorigenic macrophage markers in human cancer cohorts. We identified ADAM17, a sheddase upregulated in many cancer types, as a protein of interest. Depletion of ADAM17 in cancer cell lines reduced the expression of several pro-tumorigenic markers in neighboring macrophages in vitro as well as in mouse models. Moreover, ADAM17-/- educated macrophages demonstrated a reduced ability to induce cancer cell invasion. Using mass spectrometry-based proteomics and ELISA, we identified HB-EGF and AREG, shed by ADAM17 in the cancer cells, as the implicated molecular mediators of macrophage education. Additionally, RNA-seq and ELISA experiments revealed that ADAM17-dependent HB-EGF-ligand release induces the expression and secretion of CXCL chemokines in macrophages, which in turn stimulates cancer cell invasion.In conclusion, we provide evidence that ADAM17 mediates a paracrine EGFR-ligand-chemokine feedback loop, whereby cancer cells hijack macrophages to promote tumor progression.

Placental dysfunction influences fetal monocyte subpopulation gene expression in preterm birth

The placenta is the primary organ for immune regulation, nutrient delivery, gas exchange, protection against environmental toxins, and physiologic perturbations during pregnancy. Placental inflammation and vascular dysfunction during pregnancy are associated with a growing list of prematurity-related complications. The goal of this study was to identify differences in gene expression profiles in fetal monocytes - cells that persist and differentiate postnatally - according to distinct placental histologic domains. Here, by using bulk RNA-Seq, we report that placental lesions are associated with gene expression changes in fetal monocyte subsets. Specifically, we found that fetal monocytes exposed to acute placental inflammation upregulate biological processes related to monocyte activation, monocyte chemotaxis, and platelet function, while monocytes exposed to maternal vascular malperfusion lesions downregulate these processes. Additionally, we show that intermediate monocytes might be a source of mitogens, such as HBEGF, NRG1, and VEGFA, implicated in different outcomes related to prematurity. This is the first study to our knowledge to show that placental lesions are associated with unique changes in fetal monocytes and monocyte subsets. As fetal monocytes persist and differentiate into various phagocytic cells following birth, our study may provide insight into morbidity related to prematurity and ultimately potential therapeutic targets.

Cellular Immune Signal Exchange From Ischemic Stroke to Intestinal Lesions Through Brain-Gut Axis

As a vital pivot for the human circulatory system, the brain-gut axis is now being considered as an important channel for many of the small immune molecules’ transductions, including interleukins, interferons, neurotransmitters, peptides, and the chemokines penetrating the mesentery and blood brain barrier (BBB) during the development of an ischemic stroke (IS). Hypoxia-ischemia contributes to pituitary and neurofunctional disorders by interfering with the molecular signal release and communication then providing feedback to the gut. Suffering from such a disease on a long-term basis may cause the peripheral system’s homeostasis to become imbalanced, and it can also lead to multiple intestinal complications such as gut microbiota dysbiosis (GMD), inflammatory bowel disease (IBD), necrotizing enterocolitis (NEC), and even the tumorigenesis of colorectal carcinoma (CRC). Correspondingly, these complications will deteriorate the cerebral infarctions and, in patients suffering with IS, it can even ruin the brain’s immune system. This review summarized recent studies on abnormal immunological signal exchange mediated polarization subtype changes, in both macrophages and microglial cells as well as T-lymphocytes. How gut complications modulate the immune signal transduction from the brain are also elucidated and analyzed. The conclusions drawn in this review could provide guidance and novel strategies to benefit remedies for both IS and relative gut lesions from immune-prophylaxis and immunotherapy aspects.

Necrotizing enterocolitis: Bench to bedside approaches and advancing our understanding of disease pathogenesis

Necrotizing enterocolitis (NEC) is a devastating, multifactorial disease mainly affecting the intestine of premature infants. Recent discoveries have significantly enhanced our understanding of risk factors, as well as, cellular and genetic mechanisms of this complex disease. Despite these advancements, no essential, single risk factor, nor the mechanism by which each risk factor affects NEC has been elucidated. Nonetheless, recent research indicates that maternal factors, antibiotic exposure, feeding, hypoxia, and altered gut microbiota pose a threat to the underdeveloped immunity of preterm infants. Here we review predisposing factors, status of unwarranted immune responses, and microbial pathogenesis in NEC based on currently available scientific evidence. We additionally discuss novel techniques and models used to study NEC and how this research translates from the bench to the bedside into potential treatment strategies.

Necrotizing Enterocolitis: Clinical Features, Histopathological Characteristics, and Genetic Associations

Necrotizing enterocolitis (NEC) is an inflammatory bowel necrosis seen in premature infants. Although the etiopathogenesis of NEC is unclear, genetic factors may alter a patient's susceptibility, clinical course, and outcomes. This review draws from existing studies focused on individual genes and others based on microarray-based high-throughput discovery techniques. We have included evidence from our own studies and from an extensive literature search in the databases PubMed, EMBASE, and Scopus. To avoid bias in the identification of studies, keywords were short-listed a priori from anecdotal experience and PubMed's Medical Subject Heading (MeSH) thesaurus.

Effect of RGD functionalization and stiffness of gellan gum hydrogels on macrophage polarization and function

Macrophages, the primary effector cells in the immune response, respond rapidly to the physical or chemical properties of biomaterial implants. Balanced macrophage polarization, phagocytosis, and migration would be beneficial for implant success and tissue regeneration. Here, we investigated macrophage phenotypic changes, phagocytosis, and migration in response to RGD functionalized surfaces and changes in stiffness of gellan gum hydrogels. We also inhibited the RhoA pathway. The compressive moduli ranged from ~5 to 30 kPa. Cell population and cell spreading area of classically activated macrophages (M(LPS)) and alternatively activated macrophages (M(IL-4)) are promoted on RGD modified hydrogel. ROCK inhibitor induced the opposite effect on the cell spreading of both M(LPS) and M(IL-4) macrophages on RGD modified hydrogels. Macrophage polarization was found to be stiffness-driven and regulated by the RGD motif and blocked by the RhoA pathway. RGD functionalized hydrogel shifted M(IL-4) cells toward a more pro-inflammatory phenotype, while ROCK inhibition shifted M(LPS) cells to a more anti-inflammatory phenotype. Both M(LPS) and M(IL-4) cells on untreated hydrogels shifted to a more pro-inflammatory phenotype in the presence of aminated-PS particles. The RGD motif had a significant impact on cellular uptake, whereas cellular uptake was stiffness driven on untreated hydrogels. Cell migration of M(LPS) and M(IL-4) cells had ROCK-dependent migration. The stiffness of gellan gum hydrogels had no influence on macrophage migration rate. Collectively, our results showed that gellan gum hydrogels can be used to direct immune response, macrophage infiltration, and phagocytosis.

Role of macrophages in fetal development and perinatal disorders

In the fetus and the neonate, altered macrophage function has been implicated not only in inflammatory disorders but also in developmental abnormalities marked by altered onset, interruption, or imbalance of key structural changes. The developmental role of macrophages were first noted nearly a century ago, at about the same time when these cells were being identified as central effectors in phagocytosis and elimination of microbes. Since that time, we have made considerable progress in understanding the diverse roles that these cells play in both physiology and disease. Here, we review the role of fetal and neonatal macrophages in immune surveillance, innate immunity, homeostasis, tissue remodeling, angiogenesis, and repair of damaged tissues. We also discuss the possibility of therapeutic manipulation of the relative abundance and activation status of macrophage subsets in various diseases. This article combines peer-reviewed evidence from our own studies with results of an extensive literature search in the databases PubMed, EMBASE, and Scopus. IMPACT: We have reviewed the structure, differentiation, and classification of macrophages in the neonatal period. Neonatal macrophages are derived from embryonic, hepatic, and bone marrow precursors. Macrophages play major roles in tissue homeostasis, innate immunity, inflammation, tissue repair, angiogenesis, and apoptosis of various cellular lineages in various infectious and inflammatory disorders. Macrophages and related inflammatory mediators could be important therapeutic targets in several neonatal diseases.

Bacterial navigation for tumor targeting and photothermally-triggered bacterial ghost transformation for spatiotemporal drug release

Cancer chemotherapy is confronted with challenges regarding the effective delivery of chemotherapeutics into tumor cells after systemic administration. Herein, we propose a strategy to load drugs into probiotic E. coli Nissle 1917 (EcN) for self-guided navigation to tumor tissues and subsequently release the drugs with in situ transformation into bacterial ghosts (BGs). Chemotherapeutic agent 5-fluorouracil (FU) and macrophage phenotype regulator zoledronic acid (ZOL) are loaded into EcN through electroporation, followed by decoration of Au nanorods on the ECN surface to construct EcN_Z/F@Au. High loading levels of 5FU (8.8%) and ZOL (10.5%) are achieved as well as high retention rates of bacterial viability (87%) and motion velocity (88%). Under near infrared (NIR) illumination the photothermal effect of Au nanorods elevates the local temperature to induce the transformation of live EcN into BGs. The created transmembrane channels initiate the gradual drug release from BGs, thus representing the first attempt to control the drug release via a biological evolution. An intermittent NIR illumination causes stepwise increases in the BG formation and drug release, which could implement an external on-off control and spatiotemporal drug release. Self-guided motion of EcN promotes efficient extravasation across blood vessels and preferential accumulation of drugs in tumors. In addition to the chemotherapeutic effect of FU, the local release of ZOL from EcN_Z/F@Au enhances valid polarization of tumor-associated macrophages toward the M1 phenotype and an effective production of proinflammatory cytokines, leading to a synergistic efficacy on tumor growth inhibition. Thus, this study demonstrates a feasible strategy to integrate chemotherapy, immunotherapy, and photothermal effects in a concise manner for effective cancer treatment with few side effects. STATEMENT OF SIGNIFICANCE: Bacteria are capable to trace and colonize in hypoxic tumor tissues. Bacterial drug carriers indicate limitations in efficient drug loading and effective release modulation. Herein, we propose a strategy to load drugs into bacteria for self-guided delivery and subsequently release the drugs in tumors with in situ transformation into bacterial ghost (BGs). Drugs are loaded into live bacteria through electroporation and Au nanorods are decorated on the bacterial surface, wherein the photothermal effect, chemotherapy, and immunotherapy are integrated in a concise manner. NIR illmumination of Au nanorods elevates the local temparature, induces the BG tranformation, and activates the spatiotemporal drug release, representing the first attempt of release modulation via a biological evolution.

Sulforaphane protects intestinal epithelial cells against lipopolysaccharide-induced injury by activating the AMPK/SIRT1/PGC-1ɑ pathway

The naturally occurring isothiocyanate sulforaphane, found in vegetables, shows promising anti-inflammatory, anti-apoptosis, and anti-oxidative effects. Whether sulforaphane protects against lipopolysaccharide (LPS)-induced injury in intestinal epithelial cells is unclear. The present study examines the ability of sulforaphane to protect Caco-2 cultures from LPS-induced injury, as well as the mechanism involved. Caco-2 cells were incubated for 24 h with 1 μg/mL LPS and different concentrations of sulforaphane (0.1–10 μM). Then, various indicators of oxidative stress, inflammation, apoptosis, and intestinal permeability were assayed. Sulforaphane increased cell viability and reduced lactate dehydrogenase activity in LPS-treated Caco-2 cells in a concentration-dependent manner. Sulforaphane weakened LPS-induced increases in intestinal epithelial cell permeability and oxidative stress (based on assays of reactive oxygen species, DMA, and H₂O₂), and it increased levels of antioxidants (SOD, GPx, CAT and T-AOC). At the same time, sulforaphane weakened the ability of LPS to induce production of inflammatory cytokines (IL-1β, IL-6, IL-8 and TNF-α) and the pro-apoptotic caspases-3 and −9. Sulforaphane also upregulated p-AMPK, SIRT1, and PGC-1ɑ, whose inhibitors antagonized the compound’s protective effects. Sulforaphane can protect intestinal epithelial cells against LPS-induced changes in intestinal permeability, oxidative stress, inflammation, and apoptosis. It appears to act by activating the AMPK/SIRT1/PGC-1ɑ pathway. The drug therefore shows potential for preventing LPS-induced intestinal injury.

Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is an inflammatory disease affecting premature infants. Intestinal microbial composition may play a key role in determining which infants are predisposed to NEC and when infants are at highest risk of developing NEC. It is unclear how to optimize antibiotic therapy in preterm infants to prevent NEC and how to optimize antibiotic regimens to treat neonates with NEC. This article discusses risk factors for NEC, how dysbiosis in preterm infants plays a role in the pathogenesis of NEC, and how probiotic and antibiotic therapy may be used to prevent and/or treat NEC and its sequelae.

Enteral Feeding Interventions in the Prevention of Necrotizing Enterocolitis: A Systematic Review of Experimental and Clinical Studies

Necrotizing enterocolitis (NEC), which is characterized by severe intestinal inflammation and in advanced stages necrosis, is a gastrointestinal emergency in the neonate with high mortality and morbidity. Despite advancing medical care, effective prevention strategies remain sparse. Factors contributing to the complex pathogenesis of NEC include immaturity of the intestinal immune defense, barrier function, motility and local circulatory regulation and abnormal microbial colonization. Interestingly, enteral feeding is regarded as an important modifiable factor influencing NEC pathogenesis. Moreover, breast milk, which forms the currently most effective prevention strategy, contains many bioactive components that are known to support neonatal immune development and promote healthy gut colonization. This systematic review describes the effect of different enteral feeding interventions on the prevention of NEC incidence and severity and the effect on pathophysiological mechanisms of NEC, in both experimental NEC models and clinical NEC. Besides, pathophysiological mechanisms involved in human NEC development are briefly described to give context for the findings of altered pathophysiological mechanisms of NEC by enteral feeding interventions.

Decreased infiltration of adipose tissue macrophages and amplified inflammation of adipose tissue in obese mice with severe acute pancreatitis

OBJECTIVE

Macrophages are involved in obesity-associated inflammation and severe acute pancreatitis (SAP) development. However, the role of adipose tissue macrophages (ATMs) in obesity-related SAP has not been fully elucidated. We investigated the relationship between ATMs and inflammatory responses in SAP model mice fed a high-fat diet (HFD).

METHODS

SAP was induced in animal models via intraperitoneal injections of caerulein and lipopolysaccharide (LPS). SAP severity was evaluated, both morphologically and biochemically, and macrophage infiltration in the pancreas and epididymal adipose tissue was measured. We also analyzed apoptosis levels, polarization of the ATMs, and expression of inflammatory mediators in epididymal adipose tissue.

RESULTS

Obesity increased disease severity in SAP animals. Increased macrophage infiltration in the pancreas induced by SAP was found in both normal diet (ND)- and HFD-fed mice. Total ATM infiltration in epididymal adipose tissue was elevated by HFD, while a significant decrease in infiltration was observed in both the ND + SAP and HFD + SAP groups. The apoptosis levels of ATMs were reduced in the HFD group, but were markedly enhanced in both the ND + SAP and HFD + SAP groups compared to their respective control groups. Higher levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and monocyte chemoattractant protein-1 (MCP-1) were observed in the HFD + SAP than in the ND + SAP group. Increased proportion of M1 type ATMs was induced by both HFD and SAP.

CONCLUSIONS

Total ATM infiltration was decreased in epididymal adipose tissue of SAP animals. ATM polarization to the M1 type resulted in an amplified inflammatory response in obese mice with SAP.

The Influence of Polysaccharides-Based Material on Macrophage Phenotypes

Macrophage polarization is a key factor in determining the success of implanted tissue engineering scaffolds. Polysaccharides (derived from plants, animals, and microorganisms) are known to modulate macrophage phenotypes by recognizing cell membrane receptors. Numerous studies have developed polysaccharide-based materials into functional biomaterial substrates for tissue regeneration and pharmaceutical application due to their immunostimulatory activities and anti-inflammatory response. They are used as hydrogel substrates, surface coatings, and drug delivery carriers. In addition to their innate immunological functions, the newly endowed physical and chemical properties, including substrate modulus, pore size/porosity, surface binding chemistry, and the mole ratio of polysaccharides in hybrid materials may regulate macrophage phenotypes more precisely. Growing evidence indicates that the sulfation pattern of glycosaminoglycans and proteoglycans expressed on polarized macrophages leads to the changes in protein binding, which may alter macrophage phenotype and influence the immune response. A comprehensive understanding of how different types of polysaccharide-based materials alter macrophage phenotypic changes can be beneficial to predict transplantation/implantation outcomes. This review focuses on recent advances in promoting wound healing and balancing macrophage phenotypes using polysaccharide-based substrates/coatings and new directions to address the limitations in the current understanding of macrophage responses to polysaccharides.

Identification of Inflammatory Genes, Pathways, and Immune Cells in Necrotizing Enterocolitis of Preterm Infant by Bioinformatics Approaches

Background

Necrotizing enterocolitis (NEC) is one of the most serious gastrointestinal disease-causing high morbidity and mortality in premature infants. However, the underlying mechanism of the pathogenesis of NEC is still not fully understood.

Methods

RNA sequencing of intestinal specimens from 9 NEC and 5 controls was employed to quantify the gene expression levels. RNA sequencing was employed to quantify the gene expression levels. DESeq2 tool was used to identify the differentially expressed genes. The biological function, pathways, transcription factors, and immune cells dysregulated in NEC were characterized by gene set enrichment analysis.

Results

In the present study, we analyzed RNA sequencing data of NECs and controls and revealed that immune-related pathways were highly activated, while some cellular responses to external stimuli-related pathways were inactivated in NEC. Moreover, B cells, macrophages M1, and plasma cells were identified as the major cell types involved in NEC. Furthermore, we also found that inflammation-related transcription factor genes, such as STAT1, STAT2, and IRF2, were significantly activated in NEC, further suggesting that these TFs might play critical roles in NEC pathogenesis. In addition, NEC samples exhibited heterogeneity to some extent. Interestingly, two subgroups in the NEC samples were identified by hierarchical clustering analysis. Notably, B cells, T cells, Th1, and Tregs involved in adaptive immune were predicted to highly infiltrate into subgroup I, while subgroup II was significantly infiltrated by neutrophils. The heterogeneity of immune cells in NEC indicated that both innate and adaptive immunes might induce NEC-related inflammatory response.

Conclusions

In summary, we systematically analyzed inflammation-related genes, signaling pathways, and immune cells to characterize the NEC pathogenesis and samples, which greatly improved our understanding of the roles of inflammatory responses in NEC.

Activated M1 macrophages suppress c-kit expression via TNF-α-mediated upregulation of miR-222 in Neonatal Necrotizing Enterocolitis

BACKGROUND

Activation of intestinal macrophages is implicated in the pathogenesis of neonatal necrotizing enterocolitis (NEC), yet its precise mechanisms remain unclear.

OBJECTIVE

The purpose of this study is to investigate the role of macrophages and TNF-α via an inflammatory MicroRNA in NEC.

MATERIALS AND METHODS

Immunofluorescence (IF) staining of CD68, iNOS, and Arg-1 was employed to identify phenotypes of macrophage in the intestines of NEC infants and NEC mice. Expression of TNF-α, c-kit, and miR-222 was evaluated by qRT-PCR, Western blot, and immunochemical staining from the tissue samples.

RESULTS

Large number of M1 macrophage infiltration was found in the NEC intestines. Expression of CD68, iNOS, and TNF-α were significantly increased, while c-kit was decreased distinctly in the NEC group. In the early phase of NEC mouse model, inhibition of M1 macrophages reduced the incidence of NEC and intestinal inflammation. We found that TNF-α upregulated the expression of miRNA-222 and inhibited the expression of c-kit. Conversely, such decrease of c-kit expression could be reversed by miR-222 antagonists. Furtherly, dual-luciferase assay confirmed that c-kit can be inhibited by miR-222 directly.

CONCLUSION

Macrophages activation in NEC intestine results in an increased inflammatory response and TNF-α production, accompanied with miR-222 upregulation and c-kit suppression. Modulations of M1 macrophages, TNF-α or miR-222 may be potential therapeutic targets for NEC treatment.

Intestinal proinflammatory macrophages induce a phenotypic switch in interstitial cells of Cajal

Interstitial cells of Cajal (ICCs) are pacemaker cells in the intestine, and their function can be compromised by loss of C-KIT expression. Macrophage activation has been identified in intestine affected by Hirschsprung disease-associated enterocolitis (HAEC). In this study, we examined proinflammatory macrophage activation and explored the mechanisms by which it downregulates C-KIT expression in ICCs in colon affected by HAEC. We found that macrophage activation and TNF-α production were dramatically increased in the proximal dilated colon of HAEC patients and 3-week-old Ednrb-/- mice. Moreover, ICCs lost their C-KIT+ phenotype in the dilated colon, resulting in damaged pacemaker function and intestinal dysmotility. However, macrophage depletion or TNF-α neutralization led to recovery of ICC phenotype and restored their pacemaker function. In isolated ICCs, TNF-α-mediated phosphorylation of p65 induced overexpression of microRNA-221 (miR-221), resulting in suppression of C-KIT expression and pacemaker currents. We also identified a TNF-α/NF-κB/miR-221 pathway that downregulated C-KIT expression in ICCs in the colon affected by HAEC. These findings suggest the important roles of proinflammatory macrophage activation in a phenotypic switch of ICCs, representing a promising therapeutic target for HAEC.

Hydrogen Promotes the M1 Macrophage Conversion During the Polarization of Macrophages in Necrotizing Enterocolitis

Background: Hydrogen is protective against intestinal injury in necrotizing enterocolitis (NEC), mainly through to alleviate inflammation response. The M1 macrophages can promote inflammation. We hypothesized that hydrogen would promote the M1 macrophages conversion during the polarization and reduce the inflammatory factors in NEC. Methods: We used M1 and M2 macrophages induced from RAW264.7 cells and bone marrow-derived macrophages, models of NEC and macrophages derived from spleens, abdominal lymph nodes and lamina propria in model mice. Cytokines, CD16/32 and CD206 were measured by quantitative PCR, flow cytometry. Nuclear factor-κB (NF-κB) p65 were determined by western blot. Histology staining were used to assess the severity of NEC. Results: Macrophages were successfully polarized to M1 or M2 by assessing the expression of inflammatory factors. Pro-inflammatory factors and CD16/32 in M1 macrophages were decreased, and the expression of CD16/32 in lamina propria were inhibited after treatment with hydrogen, but the changes has no effects in other tissues. Hydrogen inhibited the NF-κB p65 in M1 macrophages nucleus and distal ileum of NEC. HE staining showed hydrogen could attenuate the severity of NEC. Conclusion: Hydrogen could attenuate the severity of NEC through promoting M1 macrophages conversion by inhibited the expression of NF-κB p65 in the nucleus.

Co-encapsulation of HNF4α overexpressing UMSCs and human primary hepatocytes ameliorates mouse acute liver failure

BACKGROUND

Acute liver failure (ALF) is a complicated condition that is characterized by global hepatocyte death and often requires immediate liver transplantation. However, this therapy is limited by shortage of donor organs. Mesenchymal stem cells (MSCs) and hepatocytes are two attractive sources of cell-based therapies to treat ALF. The combined transplantation of hepatocytes and MSCs is considered to be more effective for the treatment of ALF than single-cell transplantation. We have previously demonstrated that HNF4α-overexpressing human umbilical cord MSCs (HNF4α-UMSCs) promoted the expression of hepatic-specific genes. In addition, microencapsulation allows exchange of nutrients, forming a protective barrier to the transplanted cells. Moreover, encapsulation of hepatocytes improves the viability and synthetic ability of hepatocytes and circumvents immune rejection. This study aimed to investigate the therapeutic effect of microencapsulation of hepatocytes and HNF4α-UMSCs in ALF mice.

METHODS

Human hepatocytes and UMSCs were obtained separately from liver and umbilical cord, followed by co-encapsulation and transplantation into mice by intraperitoneal injection. LPS/D-gal was used to induce ALF by intraperitoneal injection 24 h after transplantation. In addition, Raw 264.7 cells (a macrophage cell line) were used to elucidate the effect of HNF4α-UMSCs-hepatocyte microcapsules on polarization of macrophages. The protein chip was used to define the important paracrine factors in the conditioned mediums (CMs) of UMSCs and HNF4α-UMSCs and investigate the possible mechanism of HNF4α-UMSCs for the treatment of ALF in mice.

RESULTS

HNF4α-UMSCs can enhance the function of primary hepatocytes in alginate-poly-L-lysine-alginate (APA) microcapsules. The co-encapsulation of both HNF4α-UMSCs and hepatocytes achieved better therapeutic effects in ALF mice by promoting M2 macrophage polarization and reducing inflammatory response mainly mediated by the paracrine factor HB-EGF secreted by HNF4α-UMSCs.

CONCLUSIONS

The present study confirms that the co-encapsulation of HNF4α-UMSC and hepatocytes could exert therapeutic effect on ALF mainly by HB-EGF secreted by HNF4α-UMSCs and provides a novel strategy for the treatment of ALF.

Precision-based modeling approaches for necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the leading cause of death from gastrointestinal disease in premature infants and remains stubbornly difficult to treat in many cases. Much of our understanding of NEC pathogenesis has been gained through the study of highly translational animal models. However, most models of NEC are limited by their overall complexity and by the fact that they do not incorporate human tissue. To address these limitations, investigators have recently developed precision-based ex vivo models of NEC, also termed 'NEC-in-a-dish' models, which provide the opportunity to increase our understanding of this disease and for drug discovery. These approaches involve exposing intestinal cells from either humans or animals with or without NEC to a combination of environmental and microbial factors associated with NEC pathogenesis. This Review highlights the current progress in the field of NEC model development, introduces NEC-in-a-dish models as a means to understand NEC pathogenesis and examines the fundamental questions that remain unanswered in NEC research. By answering these questions, and through a renewed focus on precision model development, the research community may finally achieve enduring success in improving the outcome of patients with this devastating disease.

Immuno-modulatory effects of macluraxanthone on macrophage phenotype and function

Macluraxanthone was previously reported to have many biological activities, including anti-cholinesterase, anti-oxidant, anti-cancer, anti-malarial and anti-inflammatory effects. The aim of the current study was to further characterise the effect of macluraxanthone on human macrophage, a type of immune cell that has been implicated in the development of various inflammatory diseases. The expression of surface markers and cytokine production by THP-1 human macrophages following treatment with macluraxanthone were investigated. Macluraxanthone was shown to promote polarisation of M1-like pro-inflammatory macrophages by increasing the percentage of macrophages expressing CD86, while decreasing their CD14, CD11b and CD80 expression. However, in the presence of the pro-inflammatory stimulus lipopolysaccharide, macluraxanthone significantly decreased TNF-α and IL-10 cytokine production.

Microglia-Derived NLRP3 Activation Mediates the Pressor Effect of Prorenin in the Rostral Ventrolateral Medulla of Stress-Induced Hypertensive Rats

Increased microglial activation and neuroinflammation within autonomic brain regions such as the rostral ventrolateral medulla (RVLM) have been implicated in stress-induced hypertension (SIH). Prorenin, a member of the brain renin-angiotensin system (RAS), can directly activate microglia. The present study aimed to investigate the effects of prorenin on microglial activation in the RVLM of SIH rats. Rats were subjected to intermittent electric foot-shocks plus noise, this stress was administered for 2 h twice daily for 15 consecutive days, and mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA) were monitored. The results showed that MAP and RSNA were augmented, and this paralleled increased pro-inflammatory phenotype (M1) switching. Prorenin and its receptor (PRR) expression and the NLR family pyrin domain containing 3 (NLRP3) activation were increased in RVLM of SIH rats. In addition, PLX5622 (a microglial depletion agent), MCC950 (a NLRP3 inhibitor), and/or PRO20 (a (Pro)renin receptor antagonist) had antihypertensive effects in the rats. The NLRP3 expression in the RVLM was decreased in SIH rats treated with PLX5622. Mito-tracker staining showed translocation of NLRP3 from mitochondria to the cytoplasm in prorenin-stimulated microglia. Prorenin increased the ROS-triggering M1 phenotype-switching and NLRP3 activation, while MCC950 decreased the M1 polarization. In conclusion, upregulated prorenin in the RVLM may be involved in the pathogenesis of SIH, mediated by activation of the microglia-derived NLRP3 inflammasome. The link between prorenin and NLRP3 in microglia provides insights for the treatment of stress-related hypertension.

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.

Colon Cancer Cell Secretes EGF to Promote M2 Polarization of TAM Through EGFR/PI3K/AKT/mTOR Pathway

Background:

Tumor environment has been recognized to affect cancer cell progression, such as tumor-associated macrophages. However, increasing evidences suggest that tumor cells are capable of regulating polarization of tumor-associated macrophages. In this study, we investigate the mechanism of how colon cancer cell impacts tumor-associated macrophages polarization.

Methods:

We employed flow cytometry to detect marker molecules on macrophage membrane, such as CD68, CD16, and CD204. In addition, we used enzyme-linked immunosorbent assay to examine the level of these cytokines (interleukin-6, interleukin-1β, interleukin-10, and Arginase-1) secreted by colon cancer cells into the culture medium. Western blot was utilized to probe downstream proteins of epidermal growth factor receptor (EGFR)/phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway.

Results:

We cocultured colon cancer cell lines (HCT8 or HCT116) with human myeloid leukemia mononuclear cells (THP-1) and found that interleukin-6 and interleukin-1β levels were reduced, and instead, interleukin-10 and Arginase-1 levels were elevated, suggesting that colon cancer cells contributed to M2 polarization of THP-1. Meanwhile, high level of various growth factors (transforming growth factor-β [TGF-β], epidermal growth factor [EGF], and hepatocyte growth factor [HGF]) was observed in the medium of THP-1 cocultured with colon cancer cells. Furthermore, the protein level of phosphorylated PI3K, AKT, and mTOR significantly increased in THP-1 cell cocultured with colon cancer cells compared to THP-1 group. Besides, we established that colon cancer cells exerted their stimulatory effect on M2 polarization of macrophage from monocyte THP-1 using EGFR antibody mAb225 and PI3K inhibitor LY294002.

Conclusion:

We provide evidence that EGF which are secreted by colon cancer cells play contributory role in M2 polarization of macrophages, which support the notion that tumor environment, including tumor-associated macrophages, can be targeted to develop effective strategies for treating cancer.

The Role of Maresins in Inflammatory Pain: Function of Macrophages in Wound Regeneration

Although acute inflammatory responses are host-protective and generally self-limited, unresolved and delayed resolution of acute inflammation can lead to further tissue damage and chronic inflammation. The mechanism of pain induction under inflammatory conditions has been studied extensively; however, the mechanism of pain resolution is not fully understood. The resolution of inflammation is a biosynthetically active process, involving specialized pro-resolving mediators (SPMs). In particular, maresins (MaRs) are synthesized from docosahexaenoic acid (DHA) by macrophages and have anti-inflammatory and pro-resolving capacities as well as tissue regenerating and pain-relieving properties. A new class of macrophage-derived molecules—MaR conjugates in tissue regeneration (MCTRs)—has been reported to regulate phagocytosis and the repair and regeneration of damaged tissue. Macrophages not only participate in the biosynthesis of SPMs, but also play an important role in phagocytosis. They exhibit different phenotypes categorized as proinflammatory M1-like phenotypes and anti-inflammatory M2 phenotypes that mediate both harmful and protective functions, respectively. However, the signaling mechanisms underlying macrophage functions and phenotypic changes have not yet been fully established. Recent studies report that MaRs help resolve inflammatory pain by enhancing macrophage phagocytosis and shifting cytokine release to the anti-inflammatory M2 phenotypes. Consequently, this review elucidated the characteristics of MaRs and macrophages, focusing on the potent action of MaRs to enhance the M2 macrophage phenotype profiles that possess the ability to alleviate inflammatory pain.

The protective effect of icariin and phosphorylated icariin against LPS-induced intestinal epithelial cells injury

Icariin (ICA) and phosphorylated icariin (pICA) have excellent antiviral and antioxidant effects. However, whether ICA and pICA cause anti-LPS-induced intestinal damage remains unclear. In this study, we used Caco-2 cells as a model to investigate the protective effects of ICA and pICA on human colonic epithelial cells and explore their potential mechanisms. Our results indicated that ICA and pICA increased cell viability and decreased lactate dehydrogenase activity in Caco-2 cells. ICA and pICA also attenuated LPS-induced changes in intestinal epithelial cell permeability and reduced the levels of oxidative stress indicators, such as reactive oxygen species, malondialdehyde, and hydrogen peroxide, in Caco-2 cells. Antioxidant indicators, such as superoxide dismutase, glutathione peroxidase, catalase and total antioxidant capacity, were increased, while the levels of IL-1β, IL-6, IL-8 and TNF-α were reduced in the ICA and pICA groups. Furthermore, ICA and pICA decreased the gene abundance and enzyme activities of caspase-3, -8, -9 and -10 in Caco-2 cells. Our data suggest that ICA and pICA effectively attenuated LPS-induced changes in the oxidative stress, inflammation, apoptosis and intestinal permeability of intestinal epithelial cells. These findings provide new insight for treating LPS-induced intestinal injury.

Irf5 deficiency in myeloid cells prevents necrotizing enterocolitis by inhibiting M1 macrophage polarization

Necrotizing enterocolitis (NEC) is a life-threatening inflammatory disease in newborns, but the mechanisms remain unclear. Interferon regulatory factor 5 (IRF5) is a master regulator of macrophage function and is essential for proinflammatory M1 macrophage polarization. Our previous data indicated that M1 macrophages promote NEC injury. Here, we investigated whether IRF5 is involved in the pathogenesis of NEC. First, we found that IRF5 was upregulated in infiltrated macrophages in human neonates with NEC compared to controls. We further confirmed IRF5 upregulation in macrophages in experimental murine NEC and that the infiltrated macrophages were predominantly polarized into the M1 but not the M2 phenotype. Myeloid-specific deficiency of Irf5, which was associated with reduced M1 macrophage polarization and systematic inflammation, dramatically prevented experimental NEC. Moreover, we found that the ablation of Irf5 in myeloid cells markedly suppressed intestinal epithelial cell apoptosis and further prevented intestinal barrier dysfunction in experimental NEC. Bioinformatic and chromatin immunoprecipitation analysis further showed that IRF5 binds to the promoters of the M1 macrophage-associated genes Ccl4, Ccl5, Tnf, and Il12b. Overall, our study provides evidence that IRF5 participates in the pathogenesis of NEC, while the deletion of Irf5 in myeloid cells prevents NEC via inhibiting M1 macrophage polarization.