IL-8 from Local Subcutaneous Wounds Regulates CD11b Activation

Interplay between mesenchymal stromal cells and the immune system after transplantation: implications for advanced cell therapy in the retina

Advanced mesenchymal stromal cell-based therapies for neurodegenerative diseases are widely investigated in preclinical models. Mesenchymal stromal cells are well positioned as therapeutics because they address the underlying mechanisms of neurodegeneration, namely trophic factor deprivation and neuroinflammation. Most studies have focused on the beneficial effects of mesenchymal stromal cell transplantation on neuronal survival or functional improvement. However, little attention has been paid to the interaction between mesenchymal stromal cells and the host immune system due to the immunomodulatory properties of mesenchymal stromal cells and the long-held belief of the immunoprivileged status of the central nervous system. Here, we review the crosstalk between mesenchymal stromal cells and the immune system in general and in the context of the central nervous system, focusing on recent work in the retina and the importance of the type of transplantation.

Skin Immunity and Tolerance: Focus on Epidermal Keratinocytes Expressing HLA-G

Although the role of epidermal cells in skin regeneration has been extensively documented, their functions in immunity and tolerance mechanisms are largely underestimated. The aim of the present review was to outline the state of knowledge on resident immune cells of hematopoietic origin hosted in the epidermis, and then to focus on the involvement of keratinocytes in the complex skin immune networks acting in homeostasis and regeneration conditions. Based on this knowledge, the mechanisms of immune tolerance are reviewed. In particular, strategies based on immunosuppression mediated by HLA-G are highlighted, as recent advances in this field open up perspectives in epidermis-substitute bioengineering for temporary and permanent skin replacement strategies.

Free Fatty Acid Receptor 1 Signaling Contributes to Migration, MMP-9 Activity, and Expression of IL-8 Induced by Linoleic Acid in HaCaT Cells

Keratinocytes and neutrophils are the main cellular components in wound healing during re-epithelization and inflammation. Free fatty acids such as linoleic acid (LA) present beneficial properties for wound healing by modulating the inflammatory response. LA is a natural ligand of free fatty acids receptor 1 (FFA1), a G protein-coupled receptor (GPCR), able to modulate inflammatory process; however, the role of FFA1 in keratinocytes and wound healing remains poorly understood. In this study, we investigated the role of FFA1 signaling in migration, matrix metalloproteinase-9 (MMP-9) activity, and IL-8 expression induced by LA in keratinocytes. We confirmed that HaCaT cells, a human keratinocyte cell line, expresses the FFA1 receptor and GW1100, a selective antagonist of FFA1, decreased LA-induced migration of HaCaT cells. Also, GW9508, a synthetic agonist of FFA1, increased migration of these cells. Furthermore, ERK1/2 and p38 MAPK inhibitors abolished the LA-induced increase in cell migration. Besides, HaCaT cells stimulated with LA or GW9508 increased the activity of MMP-9 and the expression of IL-8. GW1100 partially inhibited both responses. We further evaluated the effects of HaCaT cells conditioned media stimulated with LA or GW9508 on neutrophil chemotaxis. Conditioned media induced neutrophil chemotaxis. Furthermore, IL-8 secreted by HaCaT cells stimulated with LA or GW9508, contributed to neutrophil chemotaxis. In conclusion, LA increased migration, MMP-9 activity, and expression of IL-8 from HaCaT cells via FFA1. Hence, these results showed that the effects induced by LA in keratinocytes can be mediated through FFA1, thus explaining a possible mechanism by which this fatty acid could accelerate wound healing.

Secreted immunoregulatory proteins in the skin

The skin, thought initially to protect the body passively from pathogenic organisms and other environmental insults, is now recognised additionally as a sophisticated immune organ that actively regulates local immunity. Studies linking local innate and adaptive immunity to skin health and disease have revealed a complex network of cell communication and cytokine signalling. Here, we review the last 10 years of literature on this topic, and its relevance to skin immunity.

Modulation of Immune Responses by Mesenchymal Stromal Cells

This concise review provides an assessment of one of the most conceptually and practically important properties of mesenchymal stromal cells, their ability to modulate immune responses, including underlying cellular and molecular mechanisms and prospects of clinical application in the treatment of autoimmune and other immunological disorders.

Comprehensive Assessment of Host Responses to 5-Fluorouracil-Induced Oral Mucositis through Transcriptomic Analysis

Background

Chemotherapy plays an important role in current cancer therapy; however, several problems remain unsolved on the issue of host-therapeutics interaction. The purpose of this study was to investigate the host responses after 5-flurouracil (5-FU) administration and to find the target genes and their relationship with other cytokines in the 5-FU-induced oral mucositis (OM) mouse model through transcriptomic analysis.

Materials and Methods

Thirty-six 6 to 8 week-old male BALB/c mice were randomly divided into the control group and 5-FU-treated group. In the 5-FU group, mice received 5-FU (100 mg/kg, intraperitoneally) on day 1, day 8, day 15, day 22, and day 29, respectively. We evaluated the oral mucosal change under macroanalysis and histological examination at indicated periods, and then applied transcriptomic analysis of gene expression profile and Immunohistochemical stain to identify the target molecules related to 5-FU-induced OM.

Results

The most prominent histological change in this model was observed in the fifth week. The gene expression of Bone gamma-carboxyglutamate protein, related sequence 1 (Bglap-rs1) (–12.69-fold) and Chitinase 3-like 4 (Chi3l4) (–6.35-fold) were significantly down-regulated in this phase. The quantitative real-time PCR results also revealed the expression levels were 0.62-fold in Bglap-rs1 and 0.13-fold in Chi3l4 compared with the control group. Immunohistochemical stain showed significant expression of cluster of differentiation 11b (p<0.01), interleukin-1β (p<0.001) and tumor necrosis factor-α (p<0.05), and down-regulation of Bglap-rs1 (p<0.01) compared with the control group. By Kyoto Encyclopedia of Genes and Genomes pathway analysis, there were twenty-three pathways significantly participated in this study (p<0.05).

Conclusions

Through comprehensively transcriptomic analysis and IHC stain, we discovered several valuable pathways, verified the main pro-inflammatory cytokines, and revealed two significantly down-regulated genes in the 5-FU-induced OM model. These findings highlighted the way of seeking effective therapeutic agents for chemotherapy-induced OM in future.

L-4F inhibits lipopolysaccharide-mediated activation of primary human neutrophils

Human apolipoprotein A-I (apoA-I) mimetic L-4F inhibits acute inflammation in endotoxemic animals. Since neutrophils play a crucial role in septic inflammation, we examined the effects of L-4F, compared to apoA-I, on lipopolysaccharide (LPS)-mediated activation of human neutrophils. We performed bioassays in human blood, isolated human neutrophils (incubated in 50 % donor plasma), and isolated human leukocytes (incubated in 5 and 50 % plasma) in vitro. In whole blood, both L-4F and apoA-I inhibited LPS-mediated elevation of TNF-α and IL-6. In LPS-stimulated neutrophils, L-4F and apoA-I (40 μg/ml) also decreased myeloperoxidase and TNF-α levels; however, L-4F tended to be superior in inhibiting LPS-mediated increase in IL-6 levels, membrane lipid rafts abundance and CD11b expression. In parallel experiments, when TNF-α and IL-8, instead of LPS, was used for cell stimulation, L-4F and/or apoA-I revealed only limited efficacy. In LPS-stimulated leukocytes, L-4F was as effective as apoA-I in reducing superoxide formation in 50 % donor plasma, and more effective in 5 % donor plasma (P<0.05). Limulus ambocyte lysate (LAL) and surface plasmon resonance assays showed that L-4F neutralizes LAL endotoxin activity more effectively than apoA-I (P<0.05) likely due to avid binding to LPS. We conclude that (1) direct binding/neutralization of LPS is a major mechanism of L-4F in vitro; (2) while L-4F has similar efficacy to apoA-I in anti-endotoxin effects in whole blood, it demonstrates superior efficacy to apoA-I in aqueous solutions and fluids with limited plasma components. This study rationalizes the utility of L-4F in the treatment of inflammation that is mediated by endotoxin-activated neutrophils.

The effect of conditioned medium derived from human placental multipotent mesenchymal stromal cells on neutrophils: possible implications for placental infection

The role of human placental multipotent mesenchymal stromal cells (hPMSCs) in placental inflammation is unknown. We hypothesize that hPMSCs are involved in the early phases of placental infection. hPMSCs were isolated from term placentas and neutrophils from peripheral blood. The expression of toll-like receptors (TLRs) and cytokines by hPMSCs was determined by RT-PCR, flow cytometry and enzyme-linked immunosorbent assay. The effect of conditioned medium of hPMSCs with or without lipopolysaccharide (LPS) pretreatment on neutrophil functions: migration, apoptosis and production of reactive oxygen species (ROS) was assessed by flow cytometry and western blot. hPMSCs expressed TLR1, TLR3, TLR4, TLR6, TLR7 and TLR9. LPS stimulation increased the expression of TLR4 and the production of IL-6 and IL-8 by hPMSCs. Neutrophils exhibited chemotaxis to hPMSC-conditioned medium, which was inhibited by IL-8 depletion. Neutrophil CD11b activation was promoted by hPMSC-conditioned medium, which was further enhanced in media from hPMSCs pretreated with LPS. hPMSC-conditioned medium reduced neutrophil ROS production. Neutrophil phagocytosis was increased by LPS alone but not by hPMSC-conditioned medium with or without LPS stimulation. hPMSC-conditioned medium induced STAT3 activation in neutrophils, which was inhibited by neutralizing antibody to IL-6. hPMSC-conditioned medium rescued neutrophils from apoptosis, but this effect was significantly reduced in conditioned medium of hPMSCs with LPS pretreatment. Depletion of IL-6 from the conditioned medium further inhibited the anti-apoptotic effect on neutrophils. Our results demonstrate that hPMSCs can interact with peripheral blood neutrophils in response to inflammatory signals of the placenta. Cytokines produced by hPMSCs can induce neutrophil chemotaxis and reduce neutrophil apoptosis.

Up-regulation of cluster of differentiation (CD) 11b expression on the surface of canine granulocytes with human granulocyte-macrophage colony-stimulating factor (GM-CSF)

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a pleiotropic cytokine, sharing a common beta subunit (CDw131) with interleukins 3 and 5. GM-CSF is important for its direct and indirect involvement in host defense. In veterinary medicine, human (h) GM-CSF has been used as a substitute for canine GM-CSF to stimulate canine granulocytes and macrophages. In this study, we compared the effects of three distinct hGM-CSFs produced by bacteria, yeasts and Chinese hamster ovary (CHO) cells with those of Escherichia (E) coli-produced canine GM-CSF on the cluster of differentiation 11b (CD11b) expression in canine granulocytes. The median effective dose (ED50) of hGM-CSFs from bacteria, yeasts and CHO cells was 3.09, 4.09 and 4.27 ng/ml, respectively, with no significant difference among three. In contrast, a significant difference was observed between ED50 of canine GM-CSF (0.56 ng/ml) and three hGM-CSFs according to the paired t-test (P<0.05). We conclude that hGM-CSF can activate canine granulocytes, but the average activity of the three rhGM-CSFs was approximately 15% of that of canine GM-CSF.

Activation of basophils is a new and sensitive marker of biocompatibility in hemodialysis

The hemodialysis procedure involves contact between peripheral blood and the surface of dialyzer membranes, which may lead to alterations in the pathways of innate and adaptive immunity. We aimed to study the effect of blood–membrane interaction on human peripheral basophils and neutrophils in hemodialysis with high- and low-permeability polysulfone dialyzers. The surface expression of CD203c (basophil selection marker) and CD63 (activation marker) after activation by the bacterial peptide formyl-methionyl-leucyl-phenylalanine (fMLP) or anti-Fcε receptor I (FcεRI) antibody and the absolute number of basophils was investigated before and after hemodialysis with each of the dialyzers. Moreover, the expression on neutrophils of CD11b, the CD11b active epitope, and CD88 was analyzed in the same groups of individuals. The expression of CD63 in basophils following activation by fMLP was significantly higher in the patient group compared with that in healthy controls, but no differences were observed after activation by anti-FcεRI. During the hemodialysis procedure, the low-flux membrane induced up-regulation of CD63 expression on basophils, while passage through the high-flux membrane did not significantly alter the responsiveness. In addition, the absolute number of basophils was unchanged after hemodialysis with either of the dialyzers and compared with healthy controls. We found no significant differences in the expression of the neutrophil activation markers (CD11b, the active epitope of CD11b, and CD88) comparing the two different dialyzers before and after dialysis and healthy controls. Together, these findings suggest that alterations in basophil activity may be a useful marker of membrane bioincompatibility in hemodialysis.

Acute infection of mice with Clostridium difficile leads to eIF2α phosphorylation and pro-survival signalling as part of the mucosal inflammatory response

The current study sought to delineate the gene expression profile of the host response in the caecum and colon during acute infection with Clostridium difficile in a mouse model of infection, and to investigate the nature of the unfolded protein response in this process. The infected mice displayed a significant up-regulation in the expression of chemokines (Cxcl1, Cxcl2 and Ccl2), numerous pro-inflammatory cytokines (Ifng, Il1b, Il6, and Il17f), as well as Il22 and a number of anti-microbial peptides (Defa1, Defa28, Defb1, Slpi and Reg3g) at the site(s) of infection. This was accompanied by a significant influx of neutrophils, dendritic cells, cells of the monocyte/macrophage lineage and all major subsets of lymphocytes to these site(s). However, CD4 T cells of the untreated and C. difficile-infected mice expressed similar levels of CD69 and CD25. Neither tissue had up-regulated levels of Tbx21, Gata3 or Rorc. The caeca and colons of the infected mice showed a significant increase in eukaryotic initiation factor 2α (eIF2α) phosphorylation, but neither the splicing of Xbp1 nor the up-regulation of endoplasmic reticulum chaperones, casting doubt on the full-fledged induction of the unfolded protein response by C. difficile. They also displayed significantly higher phosphorylation of AKT and signal transducer and activator of transcription 3 (STAT3), an indication of pro-survival signalling. These data underscore the local, innate, pro-inflammatory nature of the response to C. difficile and highlight eIF2α phosphorylation and the interleukin-22-pSTAT3-RegIIIγ axis as two of the pathways that could be used to contain and counteract the damage inflicted on the intestinal epithelium.

Combined features based on MT1-MMP expression, CD11b + immunocytes density and LNR predict clinical outcomes of gastric cancer

Background

Given the complexity of tumor microenvironment, no single marker from cancer cells could adequately predict the clinical outcomes of gastric cancer (GC). The objective of this study was to evaluate the prognostic role of combined features including conventional pathology, proteinase and immune data in GC.

Methods

In addition to pathological studies, immunohistochemistry was used to assess membrane-type 1 matrix metalloproteinase (MT1-MMP) expression and CD11b + immunocytes density in three independent GC tissue microarrays containing 184 GC tissues. Separate and combined features were evaluated for their impact on overall survival (OS).

Results

We found that traditional factors including tumor size, histological grade, lymph node status, serosa invasion and TNM stage were associated with OS (P < 0.05 for all). Moreover, statistically significant differences in OS were found among lymph node ratio (LNR) subgroups (P < 0.001), MT1-MMP subgroups (P = 0.015), and CD11b + immunocytes density subgroups (P = 0.031). Most importantly, combined feature (MT1-MMP positive, low CD11b + immunocytes density and high LNR) was found by multivariate analysis to be an independent prognostic factors for OS after excluding other confounding factors (HR = 3.818 [95%CI: 2.223-6.557], P < 0.001). In addition, this combined feature had better performance in predicting clinical outcomes after surgery long before recurrence had occurred (Area under the curve: 0.689 [95%CI: 0.609-0.768], P < 0.001).

Conclusions

These findings indicate that better information on GC prognosis could be obtained from combined clinico-pathological factors, tumor cells and the tumor microenvironment.

Regulation of neutrophil apoptosis differs after in vivo transmigration to skin chambers and synovial fluid: a role for inflammasome-dependent interleukin-1β release

Short-lived neutrophils are major players in inflammation, arriving early to infected and/or injured tissues. After performed duty, neutrophils are programmed to die by apoptosis and are thereafter rapidly cleared by other phagocytes. In vitro, modulation of the apoptotic process has been thoroughly investigated in neutrophils isolated from peripheral blood, but less is known about the regulation of this process in neutrophils derived from extravascular tissues. We recently demonstrated that neutrophils having transmigrated in vivo, obtained from experimental skin chambers of healthy human subjects, are resistant to the death-delaying signals induced by a range of antiapoptotic stimuli. In the current study, we show that skin chamber neutrophils spontaneously secrete high levels of antiapoptotic interleukin (IL)-1β which delays neutrophil apoptosis. Contrary to skin chamber fluid, synovial fluid from patients with rheumatic arthritis contained only moderate levels of IL-1β, and neutrophils taken from this site were fully responsive to antiapoptotic stimulation during in vitro culture. Our data demonstrate that resistance to antiapoptotic stimulation is not a general feature of tissue neutrophils and imply that autocrine IL-1β signaling could be an important factor in determining how life and death of neutrophils is regulated in inflamed tissues.

Functional and phenotypical impairment of polymorphonuclear cells in atopic dermatitis: an additional cause for the known susceptibility to infections?

BACKGROUND

Atopic dermatitis (AD) patients present an high susceptibility to infections. The phagocytic activity of polymorphonuclear granulocytes (PMNs) is mediated by the interactions between Toll-like receptors (TLRs) and pathogen-associated molecular patterns.

OBJECTIVE

To investigate functional activity and phenotype of PMNs in AD patients.

METHODS

In vitro PMN phagocytosis and intracellular killing towards Klebsiella pneumoniae were evaluated in 24 AD patients; flow cytometry was applied to analyze PMN phenotype.

RESULTS

PMNs from AD patients displayed both reduced phagocytic activity and intracellular killing against K. pneumoniae than healthy subjects (HS). CD11b, CD66b, TLR2, TLR4 and TLR5 median fluorescence intensity (MFI) on PMN membrane were significantly higher in AD patients than in HS.

CONCLUSION

PMN functional impairment in AD patients could represent an additional cause of skin infections, coupled with other known defects in the innate immune system. The increased MFI of adhesion molecules and TLRs is rather a consequence of the increased skin barrier permeability to bacterial molecules capable of stimulating immunological reactions.