Early macrophage influx to sites of cutaneous granuloma formation is dependent on MIP-1alpha /beta released from neutrophils recruited by mast cell-derived TNFalpha

Levels of inflammatory cytokines MCP-1, CCL4, and PD-L1 in CSF differentiate idiopathic normal pressure hydrocephalus from neurodegenerative diseases

BACKGROUND

Neuroinflammatory processes have been suggested to play a role in the pathophysiology of neurodegenerative diseases and post-hemorrhagic hydrocephalus, but have rarely been investigated in patients with idiopathic normal pressure hydrocephalus (iNPH). The aim of this study was to investigate whether levels of inflammatory proteins in CSF are different in iNPH compared to healthy controls and patients with selected neurodegenerative disorders, and whether any of these markers can aid in the differential diagnosis of iNPH.

METHODS

Lumbar CSF was collected from 172 patients from a single center and represented iNPH (n = 74), Alzheimer's disease (AD) (n = 21), mild cognitive impairment (MCI) due to AD (n = 21), stable MCI (n = 22), frontotemporal dementia (n = 13), and healthy controls (HC) (n = 21). Levels of 92 inflammatory proteins were analyzed using a proximity extension assay. As a first step, differences between iNPH and HC were investigated, and proteins that differed between iNPH and HC were then compared with those from the other groups. The linear regressions were adjusted for age, sex, and plate number.

RESULTS

Three proteins showed higher (MCP-1, p = 0.0013; CCL4, p = 0.0008; CCL11, p = 0.0022) and one lower (PD-L1, p = 0.0051) levels in patients with iNPH compared to HC. MCP-1 was then found to be higher in iNPH than in all other groups. CCL4 was higher in iNPH than in all other groups, except in MCI due to AD. PD-L1 was lower in iNPH compared to all other groups, except in stable MCI. Levels of CCL11 did not differ between iNPH and the differential diagnoses. In a model based on the four proteins mentioned above, the mean area under the receiver operating characteristic curve used to discriminate between iNPH and the other disorders was 0.91.

CONCLUSIONS

The inflammatory cytokines MCP-1 and CCL4 are present at higher-and PD-L1 at lower-levels in iNPH than in the other investigated diagnoses. These three selected cytokines may have diagnostic potential in the work-up of patients with iNPH.

Cux1+ proliferative basal cells promote epidermal hyperplasia in chronic dry skin disease identified by single-cell RNA transcriptomics

Pathological dry skin is a disturbing and intractable healthcare burden, characterized by epithelial hyperplasia and severe itch. Atopic dermatitis (AD) and psoriasis models with complications of dry skin have been studied using single-cell RNA sequencing (scRNA-seq). However, scRNA-seq analysis of the dry skin mouse model (acetone/ether/water (AEW)-treated model) is still lacking. Here, we used scRNA-seq and in situ hybridization to identify a novel proliferative basal cell (PBC) state that exclusively expresses transcription factor CUT-like homeobox 1 (Cux1). Further in vitro study demonstrated that Cux1 is vital for keratinocyte proliferation by regulating a series of cyclin-dependent kinases (CDKs) and cyclins. Clinically, Cux1+ PBCs were increased in patients with psoriasis, suggesting that Cux1+ PBCs play an important part in epidermal hyperplasia. This study presents a systematic knowledge of the transcriptomic changes in a chronic dry skin mouse model, as well as a potential therapeutic target against dry skin-related dermatoses.

Leishmania major-Infected Phlebotomus duboscqi Sand Fly Bites Enhance Mast Cell Degranulation

Leishmania parasites infect mammalian hosts through the bites of sand fly vectors. The response by mast cells (MC) to the parasite and vector-derived factors, delivered by sand fly bites, has not been characterized. We analyzed MC numbers and their mediators in BALB/c mice naturally infected in the ear with Leishmania major through the bite of the sand fly vector Phlebotomus duboscqi and compared them to non-infected sand fly bites. MC were found at the bite sites of infective and non-infected sand flies throughout 48 h, showing the release of granules with intense TNF-α, histamine, and tryptase staining. At 30 min and 48 h, the MC numbers were significantly higher (p < 0.001) in infected as compared to non-infected bites or controls. Neutrophil recruitment was intense during the first 6 h in the skin of infected and non-infected sand fly bites and decreased thereafter. An influx of neutrophils also occurred in lymph nodes, where a strong TNF-α stain was observed in mononuclear cells. Our data show that MC orchestrate an early inflammatory response after infected and non-infected sand fly bites, leading to neutrophilic recruitment, which potentially provides a safe passage for the parasite within the mammalian host.

Altered early immune response after fracture and traumatic brain injury

Introduction

Clinical and preclinical data suggest accelerated bone fracture healing in subjects with an additional traumatic brain injury (TBI). Mechanistically, altered metabolism and neuro-endocrine regulations have been shown to influence bone formation after combined fracture and TBI, thereby increasing the bone content in the fracture callus. However, the early inflammatory response towards fracture and TBI has not been investigated in detail so far. This is of great importance, since the early inflammatory phase of fracture healing is known to be essential for the initiation of downstream regenerative processes for adequate fracture repair.

Methods

Therefore, we analyzed systemic and local inflammatory mediators and immune cells in mice which were exposed to fracture only or fracture + TBI 6h and 24h after injury.

Results

We found a dysregulated systemic immune response and significantly fewer neutrophils and mast cells locally in the fracture hematoma. Further, local CXCL10 expression was significantly decreased in the animals with combined trauma, which correlated significantly with the reduced mast cell numbers.

Discussion

Since mast cells and mast cell-derived CXCL10 have been shown to increase osteoclastogenesis, the reduced mast cell numbers might contribute to higher bone content in the fracture callus of fracture + TBI mice due to decreased callus remodeling.

Exploring the Immunotherapeutic Potential of Oleocanthal against Murine Cutaneous Leishmaniasis

Leishmaniasis is a major tropical disease with increasing global incidence. Due to limited therapeutic options with severe drawbacks, the discovery of alternative treatments based on natural bioactive compounds is important. In our previous studies we have pointed out the antileishmanial activities of olive tree-derived molecules. In this study, we aimed to investigate the in vitro and in vivo antileishmanial as well as the in vivo immunomodulatory effects of oleocanthal, a molecule that has recently gained increasing scientific attention. Pure oleocanthal was isolated from extra virgin olive oil through extraction and chromatography techniques. The in vitro antileishmanial effects of oleocanthal were examined with a resazurin-based assay, while its in vivo efficacy was evaluated in Leishmania major-infected BALB/c mice by determining footpad induration, parasite load in popliteal lymph nodes, histopathological outcome, antibody production, cytokine profile of stimulated splenocytes and immune gene expression, at three weeks after the termination of treatment. Oleocanthal demonstrated in vitro antileishmanial effect against both L. major promastigotes and intracellular amastigotes. This effect was further documented in vivo as demonstrated by the suppressed footpad thickness, the decreased parasite load and the inflammatory cell influx at the infection site. Oleocanthal treatment led to the dominance of a Th1-type immunity linked with resistance against the disease. This study establishes strong scientific evidence for olive tree-derived natural products as possible antileishmanial agents and provides an adding value to the scientific research of oleocanthal.

Mast-Cell Response to Leishmania mexicana and Sand-Fly Salivary Proteins Is Modulated by Orchiectomy

Mast cells (MCs) play a crucial role during Leishmania infections, which is transmitted through the bite of an infected sand fly that injects saliva together with the parasite. Sand fly saliva is a complex fluid that modulates the host immune response. In addition, hormonal factors modulate the host immune response and alter susceptibility to infections. Thus, to assess the impact of male sex hormones on the mast-cell (MC) response to Leishmania infections, we orchiectomized male mice, infected them with the parasite in the presence of sand fly salivary proteins, and analyzed the inflammatory response of MCs. Our results showed that the MC response to the parasite and vector salivary proteins differed between orchiectomized and sham-operated mice. In orchiectomized mice, MC showed a retarded activation pattern, associated with slower degranulation and weaker TNF-α, histamine, and tryptase staining in response to the infection with Leishmania mexicana combined with vector-salivary proteins, as compared to sham mice. Furthermore, neutrophil infiltration was slower in orchiectomized mice, and numbers of infected macrophages and lesion sizes were smaller. Our results show that, during Leishmania infection, male sex hormones modulate the mast-cell response against the parasite and salivary proteins of the sand fly vector, inducing an intense inflammatory response. Their absence in orchiectomized mice retards the inflammatory response, enabling better control of the infection and slower disease progression.

Comparative transcriptome analysis reveals immunoregulation mechanism of lncRNA-mRNA in gill and skin of large yellow croaker (Larimichthys crocea) in response to Cryptocaryon irritans infection

Background

Cryptocaryonosis caused by Cryptocaryon irritans is one of the major diseases of large yellow croaker (Larimichthys crocea), which lead to massive economic losses annually to the aquaculture industry of L. crocea. Although there have been some studies on the pathogenesis for cryptocaryonosis, little is known about the innate defense mechanism of different immune organs of large yellow croaker.

Results

In order to analyze the roles of long non-coding RNAs and genes specifically expressed between immune organs during the infection of C. irritans, in this study, by comparing transcriptome data from different tissues of L. crocea, we identified tissue-specific transcripts in the gills and skin, including 507 DE lncRNAs and 1592 DEGs identified in the gills, and 110 DE lncRNAs and 1160 DEGs identified in the skin. Furthermore, we constructed transcriptome co-expression profiles of L. crocea gill and skin, including 7,503 long noncoding RNAs (lncRNAs) and 23,172 protein-coding genes. Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed that the DEGs and the target genes of the DE lncRNAs in the gill were specifically enriched in several pathways related to immune such as HIF-1 signaling pathway. The target genes of DE lncRNAs and DEGs in the skin are specifically enriched in the complement and coagulation cascade pathways. Protein–protein interaction (PPI) network analysis identified 3 hub genes including NFKBIA, TNFAIP3 and CEBPB, and 5 important DE lncRNAs including MSTRG.24134.4, MSTRG.3038.5, MSTRG.27019.3, MSTRG.26559.1, and MSTRG.10983.1. The expression patterns of 6 randomly selected differentially expressed immune-related genes were validated using the quantitative real-time PCR method.

Conclusions

In short, our study is helpful to explore the potential interplay between lncRNAs and protein coding genes in different tissues of L. crocea post C. irritans and the molecular mechanism of pathogenesis for cryptocaryonosis.

Highlights

Skin and gills are important sources of pro-inflammatory molecules, and their gene expression patterns are tissue-specific after C. irritans infection.

15 DEGs and 5 DE lncRNAs were identified as hub regulatory elements after C. irritans infection

The HIF-1 signaling pathway and the complement and coagulation cascade pathway may be key tissue-specific regulatory pathways in gills and skin, respectively.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08431-w.

Neutrophil Extracellular Traps (NETs) in Cancer Metastasis

Metastasis is the leading cause of cancer related morbidity and mortality. The metastatic process involves several identifiable biological stages, including tumor cell dissemination, intravasation, and the extravasation of circulating cancer cells to facilitate colonization at a distant site. Immune cell infiltration and inflammation within the tumor microenvironment coincide with tumor progression and metastatic spread and are thought to be the key mediators of this complex process. Amongst many infiltrating cells, neutrophils have recently emerged as an important player in fueling tumor progression, both in animal models and cancer patients. The production of Neutrophil Extracellular Traps (NETs) is particularly important in the pathogenesis of the metastatic cascade. NETs are composed of web-like DNA structures with entangled proteins that are released in response to inflammatory cues in the environment. NETs play an important role in driving tumor progression both in experimental and clinical models. In this review, we aim to summarize the current advances in understanding the role of NETs in cancer, with a specific focus on their role in promoting premetastatic niche formation, interaction with circulating cancer cells, and in epithelial to mesenchymal transition during cancer metastasis. We will furthermore discuss the possible role and different treatment options for targeting NETs to prevent tumor progression.

Resolving immune cells with patrolling behaviour by magnetic resonance time-lapse single cell tracking

BACKGROUND

Immune cells show distinct motion patterns that change upon inflammatory stimuli. Monocytes patrol the vasculature to screen for pathogens, thereby exerting an early task of innate immunity. Here, we aimed to non-invasively analyse single patrolling monocyte behaviour upon inflammatory stimuli.

METHODS

We used time-lapse Magnetic Resonance Imaging (MRI) of the murine brain to dynamically track single patrolling monocytes within the circulation distant to the actual site of inflammation in different inflammatory conditions, ranging from a subcutaneous pellet model to severe peritonitis and bacteraemia.

FINDINGS

Single patrolling immune cells with a velocity of <1 µm/s could be detected and followed dynamically using time-lapse MRI. We show, that due to local and systemic stimuli the slowly patrolling behaviour of monocytes is altered systemically and differs with type, duration and strength of the underlying stimulus.

INTERPRETATION

Using time-lapse MRI, it is now possible to investigate the behaviour of single circulating monocytes over the course of the systemic immune response. Monocyte patrolling behaviour is altered systemically even before the onset of clinical symptoms distant to and depending on the underlying inflammatory stimulus.

FUNDING

This study was supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - CRC 1009 - 194468054 to AZ, CF and - CRC 1450 - 431460824 to MM, SN, HB, AZ, CF, the Joachim Herz Foundation (Add-on Fellowship for Interdisciplinary Life Sciences to MM), the Interdisciplinary Centre for Clinical Research (IZKF, core unit PIX) and the Medical Faculty of the University of Muenster (MEDK fellowship to FF and IF).

Determinants of Innate Immunity in Visceral Leishmaniasis and Their Implication in Vaccine Development

Leishmaniasis is endemic to the tropical and subtropical regions of the world and is transmitted by the bite of an infected sand fly. The multifaceted interactions between Leishmania, the host innate immune cells, and the adaptive immunity determine the severity of pathogenesis and disease development. Leishmania parasites establish a chronic infection by subversion and attenuation of the microbicidal functions of phagocytic innate immune cells such as neutrophils, macrophages and dendritic cells (DCs). Other innate cells such as inflammatory monocytes, mast cells and NK cells, also contribute to resistance and/or susceptibility to Leishmania infection. In addition to the cytokine/chemokine signals from the innate immune cells, recent studies identified the subtle shifts in the metabolic pathways of the innate cells that activate distinct immune signal cascades. The nexus between metabolic pathways, epigenetic reprogramming and the immune signaling cascades that drive the divergent innate immune responses, remains to be fully understood in Leishmania pathogenesis. Further, development of safe and efficacious vaccines against Leishmaniasis requires a broader understanding of the early interactions between the parasites and innate immune cells. In this review we focus on the current understanding of the specific role of innate immune cells, the metabolomic and epigenetic reprogramming and immune regulation that occurs during visceral leishmaniasis, and the strategies used by the parasite to evade and modulate host immunity. We highlight how such pathways could be exploited in the development of safe and efficacious Leishmania vaccines.

Basil Polysaccharide Reverses Development of Experimental Model of Sepsis-Induced Secondary Staphylococcus aureus Pneumonia

Background

Basil polysaccharide (BPS) represents a main active ingredient extracted from basil (Ocimum basilicum L.), which can regulate secondary bacterial pneumonia development in the process of sepsis-mediated immunosuppression.

Methods

In this study, a dual model of sepsis-induced secondary pneumonia with cecal ligation and puncture and intratracheal instillation of Staphylococcus aureus or Pseudomonas aeruginosa was constructed.

Results

The results indicated that BPS-treated mice undergoing CLP showed resistance to secondary S. aureus pneumonia. Compared with the IgG-treated group, BPS-treated mice exhibited better survival rate along with a higher bacterial clearance rate. Additionally, BPS treatment attenuated cell apoptosis, enhanced lymphocyte and macrophage recruitment to the lung, promoted pulmonary cytokine production, and significantly enhanced CC receptor ligand 4 (CCL4). Notably, recombinant CCL4 protein could enhance the protective effect on S. aureus-induced secondary pulmonary infection of septic mice, which indicated that BPS-induced CCL4 partially mediated resistance to secondary bacterial pneumonia. In addition, BPS priming markedly promoted the phagocytosis of alveolar macrophages while killing S. aureus in vitro, which was related to the enhanced p38MAPK signal transduction pathway activation. Moreover, BPS also played a protective role in sepsis-induced secondary S. aureus pneumonia by inducing Treg cell differentiation.

Conclusions

Collectively, these results shed novel lights on the BPS treatment mechanism in sepsis-induced secondary S. aureus pneumonia in mice.

Identification of key immune-related genes and immune infiltration in atrial fibrillation with valvular heart disease based on bioinformatics analysis

Background

Atrial fibrillation (AF) is the most common persistent arrhythmia. Valvular heart disease (VHD) and AF frequently coexist. In our study, from performing bioinformatics analysis, we sought to identify immune-related genes (IRGs) and explore the role of immune cell infiltration in AF-VHD in depth, aiming at investigating the potential molecular mechanism and developing new therapeutic targets for AF, including AF-VHD.

Methods

The gene expression of the GSE41177 and GSE79768 datasets were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were analyzed via the limma package in Bioconductor with R software. Differentially expressed immune-related genes (DEIRGs) were selected via combination ImmPort database with DEGs, and the enrichment function and pathway analysis were explored. A protein-protein interaction (PPI) network was built with a Search Tool for the Retrieval of Interacting Genes/Proteins plugin in Cytoscape. The CIBERSORT algorithm was used to evaluate immune infiltration in the left atrial (LA) tissues between AF-VHD and sinus rhythm (SR) patients. Finally, a correlation analysis between key DEIRGs and infiltrating immune cells was performed.

Results

A total of 130 DEIRGs were detected. Enrichment function of DEIRGs demonstrated that they are significant in immune and inflammatory responses. The key DEIRGs assessed by the PPI network and involved in both the immune and inflammatory responses were the C-X-C motif chemokine ligand (CXCL) 1, pro-platelet basic protein (PPBP), CXCL12, and C-C motif chemokine ligand 4 (CCL4). The immune infiltration findings indicated that, compared with the LA tissues from SR patients, the tissues from AF-VHD patients contained a higher proportion of gamma delta T cells, but a lower proportion of CD8 and regulatory T cells. The results of correlation analysis demonstrated that CXCL1 was positively correlated with activated mast cells and significantly negatively correlated with resting mast cells. PPBP, CXCL12, and CCL4 were positively correlated with the infiltration of various immune cells, such as neutrophils, plasma cells, and resting dendritic cells.

Conclusions

The key immune-related genes and the differences in immune infiltration in LA tissues play an essential role in the occurrence and progression of AF-VHD.

Directional mast cell degranulation of tumor necrosis factor into blood vessels primes neutrophil extravasation

Tissue resident mast cells (MCs) rapidly initiate neutrophil infiltration upon inflammatory insult, yet the molecular mechanism is still unknown. Here, we demonstrated that MC-derived tumor necrosis factor (TNF) was crucial for neutrophil extravasation to sites of contact hypersensitivity-induced skin inflammation by promoting intraluminal crawling. MC-derived TNF directly primed circulating neutrophils via TNF receptor-1 (TNFR1) while being dispensable for endothelial cell activation. The MC-derived TNF was infused into the bloodstream by directional degranulation of perivascular MCs that were part of the vascular unit with access to the vessel lumen. Consistently, intravenous administration of MC granules boosted neutrophil extravasation. Pronounced and rapid intravascular MC degranulation was also observed upon IgE crosslinking or LPs challenge indicating a universal MC potential. Consequently, the directional MC degranulation of pro-inflammatory mediators into the bloodstream may represent an important target for therapeutic approaches aimed at dampening cytokine storm syndromes or shock symptoms, or intentionally pushing immune defense.

Harnessing the Power of Mast Cells in unconventional Immunotherapy Strategies and Vaccine Adjuvants

Mast cells are long-lived, granular, myeloid-derived leukocytes that have significant protective and repair functions in tissues. Mast cells sense disruptions in the local microenvironment and are first responders to physical, chemical and biological insults. When activated, mast cells release growth factors, proteases, chemotactic proteins and cytokines thereby mobilizing and amplifying the reactions of the innate and adaptive immune system. Mast cells are therefore significant regulators of homeostatic functions and may be essential in microenvironmental changes during pathogen invasion and disease. During infection by helminths, bacteria and viruses, mast cells release antimicrobial factors to facilitate pathogen expulsion and eradication. Mast cell-derived proteases and growth factors protect tissues from insect/snake bites and exposure to ultraviolet radiation. Finally, mast cells release mediators that promote wound healing in the inflammatory, proliferative and remodelling stages. Since mast cells have such a powerful repertoire of functions, targeting mast cells may be an effective new strategy for immunotherapy of disease and design of novel vaccine adjuvants. In this review, we will examine how certain strategies that specifically target and activate mast cells can be used to treat and resolve infections, augment vaccines and heal wounds. Although these strategies may be protective in certain circumstances, mast cells activation may be deleterious if not carefully controlled and any therapeutic strategy using mast cell activators must be carefully explored.

Leishmania Immunity: Advancing Immunotherapy and Vaccine Development

Parasitic diseases still constitute a major global health problem affecting billions of people around the world. These diseases are capable of becoming chronic and result in high morbidity and mortality. Worldwide, millions of people die each year from parasitic diseases, with the bulk of those deaths resulting from parasitic protozoan infections. Leishmaniasis, which is a disease caused by over 20 species of the protozoan parasite belonging to the genus Leishmania, is an important neglected disease. According to the World Health Organization (WHO), an estimated 12 million people are currently infected in about 98 countries and about 2 million new cases occur yearly, resulting in about 50,000 deaths each year. Current treatment methods for leishmaniasis are not very effective and often have significant side effects. In this review, we discussed host immunity to leishmaniasis, various treatment options currently being utilized, and the progress of both immunotherapy and vaccine development strategies used so far in leishmaniasis. We concluded with insights into what the future holds toward the fight against this debilitating parasitic disease.

Development and characterization of novel mouse monoclonal antibodies against chicken chemokine CC motif ligand 4

Chemokine (C-C motif) ligand (CCL) 4 is a CC chemokine subfamily member defined by the sequential positioning of conserved cysteine residues. Upon the binding of G-protein-coupled receptors on the cell surface, CCL4 mediates a diverse set of biological processes including chemotaxis, tumorigenesis, homeostasis and thymopoiesis. Although the physiological roles of mammalian CCL4s were elucidated >20 years ago, there is limited information on the biological activities of chicken CCL4 (chCCL4). In the present study, we developed and characterized mouse monoclonal antibodies (mAbs) against chCCL4 to characterize better the immunological properties of chCCL4. Out of initial screening of >400 clones, two mAbs detecting chCCL4, 1A12 and 15D9, were identified and characterized using western blotting and chCCL4-specific antigen-capture enzyme-linked immunosorbent assay, and their neutralizing activity was validated by chCCL4-induced peripheral blood mononuclear cell chemotaxis assay. Furthermore, the intracellular expression of chCCL4 in various chicken cells by immunocytochemistry and flow cytometry was confirmed using 1A12 and 15D9 mAbs. These results collectively indicate that 1A12 and 15D9 mAbs specifically detect chicken CCL4 and they will be valuable immune reagents for basic and applied studies in avian immunology.

Clinical features and monocyte/macrophage subsets characterization in granulomatous vs non-granulomatous Crohn's disease

Aims: Granuloma, mainly composed of macrophages, is a histological feature of Crohn's disease (CD). However, its significance in CD has not been investigated adequately. Our study aims to address this issue by comparing the clinical manifestations and monocyte/macrophage subtypes between granulomatous and non-granulomatous CD.Materials and methods: Demographics, symptoms, endoscopic manifestations, histopathological features, and Montreal classification of patients with and without granulomas were compared. Flow cytometry was used to determine the phagocytosis and subsets of monocytes. ELISA was used to measure the plasma levels of TNF-α, IL-6, IL-1β, IL-10, CCL22, and TGF-β1. Immunohistochemistry was performed to quantify the expression of CD68, CD163 and iNOS.Results: Of the222 CD patients enrolled, granulomas were detected in 90. Compared with non-granulomatous CD patients, those with granulomas had younger age, increased rates of diarrhea and perianal complications, along with higher endoscopic score. Intestinal stenosis and crypt abscess were more frequently observed in granulomatous CD patients. A defective phagocytosis of monocytes was observed in granulomatous CD patients. Meanwhile, higher percentages of intermediate and non-classic monocytes, with a lower percentage of classic monocyte were found in them. Besides, they had higher levels of TGF-β1 and IL-10, a lower level of TNF-α, an increased ratio of CD163⁺/CD68⁺cells, and a decreased ratio of iNOS⁺/CD68⁺ cells.Conclusions: Granulomatous CD patients exhibited different manifestations compared with their non-granulomatous counterparts. More aggressive therapy may be needed in granulomatous CD patients. Furthermore, the heterogeneity of monocyte/macrophage subsets and altered plasma cytokine may underlie the difference between those two groups.

Prunus serrulata var. spontanea inhibits mast cell activation and mast cell-mediated anaphylaxis

ETHNOPHARMACOLOGICAL RELEVANCE

A promising approach to treat a variety of diseases are considered as complementary and alternative herbal medicines. Prunus serrulata var. spontanea L. (Rosaceae) is used as herbal medicine to treat allergic diseases according to the Donguibogam, a tradition medical book of the Joseon Dynasty in Korea.

AIM OF THE STUDY

We prepared the aqueous extract of the bark of P. serrulata (AEBPS) and aimed to investigate the effects in mouse anaphylaxis models and various types of mast cells, including RBL-2H3, primary cultured peritoneal and bone marrow-derived mast cells.

MATERIALS AND METHODS

We used ovalbumin (OVA)-induced active systemic anaphylaxis (ASA) and immunoglobulin (Ig) E-mediated passive cutaneous anaphylaxis (PCA) models, in vivo. The control drug dexamethasone (10 mg/kg) was used to compare the effectiveness of AEBPS (1-100 mg/kg). In vitro, IgE-stimulated mast cells were used to confirm the role of AEBPS (1-100 μg/mL). For statistical analyses, p values less than 0.05 were considered to be significant.

RESULTS

In ASA model, oral administration of AEBPS suppressed the hypothermia and increased level of serum histamine in a dose-dependent manner. AEBPS attenuated the serum IgE, OVA-specific IgE, and interleukin (IL)-4. Oral administration of AEBPS also blocked mast cell-dependent PCA. AEBPS suppressed degranulation of mast cells by reducing intracellular calcium level in mast cells. AEBPS inhibited tumor necrosis factor-α and IL-4 expression and secretion in a concentration-dependent manner through the reduction of nuclear factor-κB.

CONCLUSIONS

On the basis of these findings, AEBPS could serve as a potential therapeutic target for the management of mast cell-mediated allergic inflammation and as a regulator of mast cell activation.

The Cooperative Induction of CCL4 in Human Monocytic Cells by TNF-α and Palmitate Requires MyD88 and Involves MAPK/NF-κB Signaling Pathways

Chronic low-grade inflammation, also known as metabolic inflammation, is a hallmark of obesity and parallels with the presence of elevated circulatory levels of free fatty acids and inflammatory cytokines/chemokines. CCL4/MIP-1β chemokine plays a key role in the adipose tissue monocyte recruitment. Increased circulatory levels of TNF-α, palmitate and CCL4 are co-expressed in obesity. We asked if the TNF-α/palmitate could interact cooperatively to augment the CCL4 production in human monocytic cells and macrophages. THP-1 cells/primary macrophages were co-treated with TNF-α/palmitate and CCL4 mRNA/protein expression was assessed using qRT-PCR/ELISA. TLR4 siRNA, a TLR4 receptor-blocking antibody, XBlue™-defMyD cells and pathway inhibitors were used to decipher the signaling mechanisms. We found that TNF-α/palmitate co-stimulation augmented the CCL4 expression in monocytic cells and macrophages compared to controls (p < 0.05). TLR4 suppression or neutralization abrogated the CCL4 expression in monocytic cells. Notably, CCL4 cooperative induction in monocytic cells was: (1) Markedly less in MyD88-deficient cells, (2) IRF3 independent, (3) clathrin dependent and (4) associated with the signaling mechanism involving ERK1/2, c-Jun, JNK and NF-κB. In conclusion, TNF-α/palmitate co-stimulation promotes the CCL4 expression in human monocytic cells through the mechanism involving a TLR4-MyD88 axis and MAPK/NF-κB pathways. These findings unravel a novel mechanism of the cooperative induction of CCL4 by TNF-α and palmitate which could be relevant to metabolic inflammation.

Neutrophils, eosinophils, and mast cells in the intestinal wall of dogs naturally infected with Leishmania infantum

Visceral leishmaniasis (VL) is a disease caused by the protozoa Leishmania infantum and can cause an inflammatory reaction in the gastrointestinal tract, however the role of granulocytic cells (neutrophils, eosinophils, and mast cells) in the intestine of dogs infected is not fully understood. We performed a quantitative analysis these cells in the intestinal wall of dogs with canine visceral leishmaniasis (CVL). Twenty dogs were assigned to one of three groups: group 1 (G1, n=8), dogs with CVL and L. infantum amastigotes in the intestine; group 2 (G2, n=9), dogs with CVL but without intestinal amastigotes; and group 3 (G3, n=3), uninfected dogs (control group). Granulocytic cells were counted in the crypt-villus unit (mucosa), submucosa, and muscle layer of the intestinal mucosa. Cell counts were higher in the intestinal wall of dogs from G2 followed by G1 and G3 (p≤0.05). In G1, there was a low inverse correlation between parasite burden of the small intestine and granulocyte counts (r= -0.1, p≤0.01). However, in G2 dogs, mast cell and eosinophil numbers showed positive correlation (r=0.85, p≤0.01). The granulocytic cell hyperplasia observed in the intestine of L. infantum-infected dogs suggests that these cells may be involved in the cell-mediated immune response for parasite elimination.

Mast cells within cellular networks

Mast cells are highly versatile in terms of their mode of activation by a host of stimuli and their ability to flexibly release a plethora of biologically highly active mediators. Within the immune system, mast cells can best be designated as an active nexus interlinking innate and adaptive immunity. Here we try to draw an arc from initiation of acute inflammatory reactions to microbial pathogens to development of adaptive immunity and allergies. This multifaceted nature of mast cells is made possible by interaction with multiple cell types of immunologic and nonimmunologic origin. Examples for the former include neutrophils, eosinophils, T cells, and professional antigen-presenting cells. These interactions allow mast cells to orchestrate inflammatory innate reactions and complex adaptive immunity, including the pathogenesis of allergies. Important partners of nonimmunologic origin include cells of the sensory neuronal system. The intimate association between mast cells and sensory nerve fibers allows bidirectional communication, leading to neurogenic inflammation. Evidence is accumulating that this mast cell/nerve crosstalk is of pathophysiologic relevance in patients with allergic diseases, such as asthma.

Mast cells as protectors of health

Mast cells (MCs), which are well known for their effector functions in T_H2-skewed allergic and also autoimmune inflammation, have become increasingly acknowledged for their role in protection of health. It is now clear that they are also key modulators of immune responses at interface organs, such as the skin or gut. MCs can prime tissues for adequate inflammatory responses and cooperate with dendritic cells in T-cell activation. They also regulate harmful immune responses in trauma and help to successfully orchestrate pregnancy. This review focuses on the beneficial effects of MCs on tissue homeostasis and elimination of toxins or venoms. MCs can enhance pathogen clearance in many bacterial, viral, and parasitic infections, such as through Toll-like receptor 2-triggered degranulation, secretion of antimicrobial cathelicidins, neutrophil recruitment, or provision of extracellular DNA traps. The role of MCs in tumors is more ambiguous; however, encouraging new findings show they can change the tumor microenvironment toward antitumor immunity when adequately triggered. Uterine tissue remodeling by α-chymase (mast cell protease [MCP] 5) is crucial for successful embryo implantation. MCP-4 and the tryptase MCP-6 emerge to be protective in central nervous system trauma by reducing inflammatory damage and excessive scar formation, thereby protecting axon growth. Last but not least, proteases, such as carboxypeptidase A, released by FcεRI-activated MCs detoxify an increasing number of venoms and endogenous toxins. A better understanding of the plasticity of MCs will help improve these advantageous effects and hint at ways to cut down detrimental MC actions.

Imaging, myeloid precursor immortalization, and genome editing for defining mechanisms of leukocyte recruitment in vivo

Recruitment of leukocytes from the blood to sites of inflammation poses a promising target for new diagnostic and therapeutic approaches. We aimed to develop a novel method to non-invasively analyze molecular mechanisms of leukocyte migration in pre-clinical models of inflammation in vivo. Methods: We used the ER-HoxB8 system to transiently immortalize murine myeloid precursors from wildtype and CD18- as well as MRP14-deficient mice. A VLA4α-/- cell line was generated by CRISPR/Cas9-mediated gene editing. We analyzed the migration of wildtype and knockout leukocytes in vivo by optical and nuclear imaging in mice with irritant contact dermatitis, cutaneous granuloma, experimental arthritis and myocardial infarction. Results: Transient immortalization, gene editing and in vivo imaging can be combined to analyze migratory mechanisms of murine leukocytes, even for gene deletions resulting in lethal phenotypes in mice. We reliably confirmed known migratory defects of leukocytes deficient for the adhesion molecules CD18 or VLA4α. Also, using our new method we identified a new role of the most abundant calcium-binding proteins in phagocytes and major alarmins in many inflammatory diseases, MRP8 and MRP14, for transmigration in vivo. Conclusion: We provide a combinatorial approach to rapidly characterize molecular mechanisms of leukocyte recruitment in vivo, with the potential to aid in identification of diagnostic and therapeutic targets in inflammatory pathologies.

The Role of Mast Cells in Tuberculosis: Orchestrating Innate Immune Crosstalk?

Tuberculosis causes more annual deaths globally than any other infectious disease. However, progress in developing novel vaccines, diagnostics, and therapies has been hampered by an incomplete understanding of the immune response to Mycobacterium tuberculosis (Mtb). While the role of many immune cells has been extensively explored, mast cells (MCs) have been relatively ignored. MCs are tissue resident cells involved in defense against bacterial infections playing an important role mediating immune cell crosstalk. This review discusses specific interactions between MCs and Mtb, their contribution to both immunity and disease pathogenesis, and explores their role in orchestrating other immune cells against infections.

Role of Mast Cells in clearance of Leishmania through extracellular trap formation

Mast Cells (MCs) are one of the first immune cells encountered by invading pathogens. Their presence in large numbers in the superficial dermis, where Leishmania is encountered, suggests that they may play a critical role in immune responses to Leishmania. In this study the interactions of Leishmania donovani, the causative agent of visceral Leishmaniasis, and Leishmania tropica, the causative agent of cutaneous Leishmaniasis with MCs were studied. Co-culture of Leishmania with Peritoneal Mast Cells (PMCs) from BALB/c mice and Rat Basophilic Leukaemia (RBL-2H3) MCs led to significant killing of L. tropica and to a lesser extent of L. donovani. Also, while there was significant uptake of L. tropica by MCs, L. donovani was not phagocytosed. There was significant generation of Reactive Oxygen Species (ROS) by MCs on co-culture with these species of Leishmania which may contribute to their clearance. Interactions of MCs with Leishmania led to generation of MC extracellular traps comprising of DNA, histones and tryptase probably to ensnare these pathogens. These results clearly establish that MCs may contribute to host defences to Leishmania in a differential manner, by actively taking up these pathogens, and also by mounting effector responses for their clearance by extracellular means.

[What is a granuloma?]

The histogenesis of granulomata is dependent on various cell types. The typical composition is a center of macrophages/histiocytes with lymphocytes at the border. The sequence of events leading to granuloma formation is regulated by various cell types and cytokines: While Th1-associated mechanisms promote granuloma development, it appears that regulatory T cells as well as M2 macrophages together with interleukin (IL)-10 and IL-13 lead to their dissociation and tissue healing. There is a strong correlation between structure and function of granulomas. Chronic inflammatory granulomatous skin diseases are primarily based on dysfunctional downmodulation of inflammatory processes that lead to and maintain granuloma formation.

New Insights into the Pro-Inflammatory Activities of Ang1 on Neutrophils: Induction of MIP-1β Synthesis and Release

We reported the expression of angiopoietin Tie2 receptor on human neutrophils and the capacity of angiopoietins (Ang1 and Ang2) to induce pro-inflammatory activities, such as platelet-activating factor synthesis, β₂-integrin activation and neutrophil migration. Recently, we observed differential effects between both angiopoietins, namely, the capacity of Ang1, but not Ang2, to promote rapid interleukin-8 synthesis and release, as well as neutrophil viability. Herein, we addressed whether Ang1 and/or Ang2 could modulate the synthesis and release of macrophage inflammatory protein-1β (MIP-1β) by neutrophils. Neutrophils were isolated from blood of healthy volunteers; intracellular and extracellular MIP-1β protein concentrations were assessed by ELISA. After 24 hours, the basal intracellular and extracellular MIP-1β protein concentrations were ≈500 and 100 pg/10⁶ neutrophils, respectively. Treatment with Ang1 (10 nM) increased neutrophil intracellular and extracellular MIP-1β concentrations by 310 and 388% respectively. Pretreatment with PI3K (LY294002), p38 MAPK (SB203580) and MEK (U0126) inhibitors completely inhibited Ang1-mediated increase of MIP-1β intracellular and extracellular protein levels. Pretreatment with NF-κB complex inhibitors, namely Bay11-7085 and IKK inhibitor VII or with a transcription inhibitor (actinomycin D) and protein synthesis inhibitor (cycloheximide), did also abrogate Ang1-mediated increase of MIP-1β intracellular and extracellular protein levels. We validated by RT-qPCR analyses the effect of Ang1 on the induction of MIP-1β mRNA levels. Our study is the first one to report Ang1 capacity to induce MIP-1β gene expression, protein synthesis and release from neutrophils, and that these effects are mediated by PI3K, p38 MAPK and MEK activation and downstream NF-κB activation.

Neutrophil-derived chemokines on the road to immunity

During recent years, it has become clear that polymorphonuclear neutrophils are remarkably versatile cells, whose functions go far beyond phagocytosis and killing. In fact, besides being involved in primary defense against infections-mainly through phagocytosis, generation of toxic molecules, release of toxic enzymes and formation of extracellular traps-neutrophils have been shown to play a role in finely regulating the development and the evolution of inflammatory and immune responses. These latter neutrophil-mediated functions occur by a variety of mechanisms, including the production of newly manufactured cytokines. Herein, we provide a general overview of the chemotactic cytokines/chemokines that neutrophils can potentially produce, either under inflammatory/immune reactions or during their activation in more prolonged processes, such as in tumors. We highlight recent observations generated from studying human or rodent neutrophils in vitro and in vivo models. We also discuss the biological significance of neutrophil-derived chemokines in the context of infectious, neoplastic and immune-mediated diseases. The picture that is emerging is that, given their capacity to produce and release chemokines, neutrophils exert essential functions in recruiting, activating and modulating the activities of different leukocyte populations.

Distinct Cutaneous Manifestations and Cold-Induced Leukocyte Activation Associated With PLCG2 Mutations

IMPORTANCE

PLCG2-associated antibody deficiency and immune dysregulation (PLAID) is a newly characterized immunodeficiency syndrome associated with distinct cutaneous features. Awareness of the cutaneous skin findings associated with PLAID may facilitate diagnosis and improve patient care.

OBJECTIVES

To characterize the cutaneous manifestations of PLAID and identify potential cellular mechanisms of the disease.

DESIGN, SETTING, AND PARTICIPANTS

In this retrospective analysis of patients with PLAID and PLAID-like disease evaluated at the National Institutes of Health from January 1, 2005, through December 31, 2014, patients with deletions in PLCG2 leading to PLAID and patients with PLAID-like disease for whom a PLAID mutation was not identified were studied.

MAIN OUTCOMES AND MEASURES

Characterization of cutaneous manifestations of PLAID and PLAID-like disease and analysis of PLAID immune cell activation.

RESULTS

Among 36 patients with PLAID and PLAID-like phenotypes, all of whom had evaporative cold urticaria, 8 patients had a history of unique neonatal-onset ulcerative and cutaneous lesions in cold-sensitive regions of the body. Granulomatous skin lesions sparing warm regions (eg, flexural surfaces and skinfolds) were identified in 4 patients. Neutrophils and monocytes from patients with PLAID exhibited enhanced baseline activation in vitro, which was potentiated by ambient temperature exposure.

CONCLUSIONS AND RELEVANCE

Collectively, these findings suggest that early identification of neonatal lesions may help in the diagnosis of PLAID and that leukocyte hyperactivation may underlie cutaneous lesions in patients with PLAID. Further characterization of mechanisms underlying leukocyte hyperactivation may contribute to the fundamental understanding of granuloma formation.

Potential effector and immunoregulatory functions of mast cells in mucosal immunity

Mast cells (MCs) are cells of hematopoietic origin that normally reside in mucosal tissues, often near epithelial cells, glands, smooth muscle cells, and nerves. Best known for their contributions to pathology during IgE-associated disorders such as food allergy, asthma, and anaphylaxis, MCs are also thought to mediate IgE-associated effector functions during certain parasite infections. However, various MC populations also can be activated to express functional programs--such as secreting preformed and/or newly synthesized biologically active products--in response to encounters with products derived from diverse pathogens, other host cells (including leukocytes and structural cells), damaged tissue, or the activation of the complement or coagulation systems, as well as by signals derived from the external environment (including animal toxins, plant products, and physical agents). In this review, we will discuss evidence suggesting that MCs can perform diverse effector and immunoregulatory roles that contribute to homeostasis or pathology in mucosal tissues.

Eosinophils and mast cells in leishmaniasis

Leishmania spp. are parasitic protozoa endemic in tropical and subtropical regions and the causative agent of leishmaniasis, a collection of syndromes whose clinical manifestations vary according to host and pathogen factors. Leishmania spp. are inoculated into the mammalian host by the bite of an infected sand fly, whereupon they are taken up by phagocytosis, convert into the replicative amastigote stage within macrophages, reproduce, spread to new macrophages and cause disease manifestations. A curative response against leishmaniasis depends in the classical activation of macrophages and the IL-12-dependent onset of an adaptive type 1 response characterized by the production of IFN-γ. Emerging evidence suggests that neutrophils, dendritic cells and other immune cells can serve as either temporary or stable hosts for Leishmania spp. Furthermore, it is becoming apparent that the initial interactions of the parasite with resident or early recruited immune cells can shape both the macrophage response and the type of adaptive immune response being induced. In this review, we compile a growing number of studies demonstrating how the earliest interactions of Leishmania spp. with eosinophils and mast cells influence the macrophage response to infection and the development of the adaptive immune response, hence, determining the ultimate outcome of infection.

Mast cells protect from skin tumor development and limit tumor growth during cutaneous de novo carcinogenesis in a Kit-dependent mouse model

Epidermal tumors belong to the most frequent type of neoplasms, and tumor-associated accumulation of mast cells (MCs) has first been observed more than a century ago. Therefore, MCs have been implicated in tumor development and growth; however, the results regarding the role of MC in cutaneous de novo carcinogenesis are still controversially discussed. Here, we subjected MC-deficient Kit(W) /Kit(W-v) mice to chemical skin carcinogenesis. Tumors were induced using the carcinogen 7,12-dimethylbenz[a]-anthracene and subsequent treatment with the tumor promoter 12-tetradecanoyl-phorbol-13-acetat. The treatment resulted in pronounced inflammatory cell infiltrates that were diminished in MC-deficient animals. Unexpectedly, tumor development and growth was significantly increased in MC-deficient Kit(W) /Kit(W-v) mice. The repair of their MC deficiency by local adoptive transfer of MCs normalized tumor incidence and growth. The recruitment of skin-infiltrating immune cells, particularly of F4/80+ monocytes, Gr-1+ granulocytes, B220+ B cells and CD8+ T lymphocytes, to sites of tumor development was, in part, also controlled by MCs. Recent evidence indicated the importance of local antitumor tissue immunity which prevents tumor development. These findings suggest a critical role for MCs in mediating these host antitumor immune responses in the skin.

Neutrophil-derived cytokines: facts beyond expression

Polymorphonuclear neutrophils, besides their involvement in primary defense against infections - mainly through phagocytosis, generation of toxic molecules, release of enzymes, and formation of extracellular traps - are also becoming increasingly important for their contribution to the fine regulation in development of inflammatory and immune responses. These latter functions of neutrophils occur, in part, via their de novo production and release of a large variety of cytokines, including chemotactic cytokines (chemokines). Accordingly, the improvement in technologies for molecular and functional cell analysis, along with concomitant advances in cell purification techniques, have allowed the identification of a continuously growing list of neutrophil-derived cytokines, as well as the characterization of their biological implications in vitro and/or in vivo. This short review summarizes crucial concepts regarding the modalities of expression, release, and regulation of neutrophil-derived cytokines. It also highlights examples illustrating the potential implications of neutrophil-derived cytokines according to recent observations made in humans and/or in experimental animal models.

TLR4-mediated blunting of inflammatory responses to eccentric exercise in young women

This study assessed the inflammatory response mediated by the toll-like receptor 4 (TLR4) signaling pathway after acute eccentric exercise before and after an eccentric training program in women. Twenty women performed two acute eccentric bouts using a squat machine over a ~9 week interval. The training group (TG) carried out an eccentric training program during 6 weeks, while the control group (CG) did not follow any training. Protein content of markers involved in the TLR4-mediated activation of several nuclear transcription factors, such as nuclear factor κB (NF-κB), and interferon regulatory transcription factor 3 (IRF3), was analyzed. The inflammatory response after the first acute bout was similar between TG and CG, showing an upregulation of all the markers analyzed, with the exception of IRF3. After the second bout, the upregulation of TLR4 signaling pathway was blunted in TG, but not in CG, through both the myeloid differentiation factor 88- and toll/interleukin-1 receptor domain containing adapter inducing interferon-β-dependent pathways. These results highlight the role of the TLR4 in controlling the exercise-induced inflammatory response in young women. More importantly, these data suggest eccentric training may help to prevent TLR4 activation principally through NF-κB, and perhaps IRF3, downstream signaling in this population.

Genetically Modified Mice as a Tool to Study Inflammatory Skin Diseases

Although mice have a long tradition as models for human skin diseases, they have recently received increasingly more attention. This is because of the rapid advancement of genetic engineering methods which made it possible to create mice with precisely defined genetic changes. Many of these mice develop impressive and sometimes unexpected, puzzling phenotypes. Their interpretation is a major challenge to the basic researcher and can often be ameliorated by the input of an experienced dermatologist. Together with recent examples of genetically modified mouse models of inflammatory skin diseases we give a short overview of the methods used to generate such mice, describe possible ways to analyse them, and discuss problems that arise in the interpretation of the findings.

A Case of Vulvitis Granulomatosa

Merkersson-Rosenthal syndrome (MRS) is characterized by cheilitis or pareitis granulomatosa, facial palsy, and fissured tongue. Sometimes the forehead, eyelids and chin are involved, and occasionally genital lesions are present. A vulval lesion of MRS is named vulvitis granulomatosa. Tranilast has been described as an effective treatment for cases of MRS, granulomatous cheilitis, and granulomatous blepharitis. Herein we report a successful treatment with tranilast of an adult female patient with vulvitis granulomatosa.

Regulation of pancreatic inflammation by connective tissue growth factor (CTGF/CCN2)

Pancreatitis is caused by long-term heavy alcohol consumption, which results in injury and death of pancreatic acinar cells (PAC). The PAC play a pivotal role in mediating early inflammatory responses but the underlying mechanisms remain poorly understood. Treatment of C57BL/6 mice with ethanol and cerulein resulted in increased staining for acinar interleukin- 1b (IL-1b), chemokine (C-C motif) ligand 3 (CCL3), or connective tissue growth factor (CTGF/CCN2) by Day 16 and this was associated with increased infiltration of F4/80-positive macrophages and increased expression of pancreatic CTGF/CCN2 mRNA. Compared with wild-type Swiss Webster mice, ethanol treatment of pan-green fluorescent protein (GFP)-CTGF/CCN2 transgenic mice caused enhanced acinar staining for GFP or CTGF/CCN2 and a significant increase in pancreatic infiltration of F4/80-positive macrophages or NIMP-R14-positive neutrophils. Treatment of primary mouse PAC or the rat AR42J PAC line with ethanol or CTGF/CCN2 resulted in enhanced expression of IL-1b or CCL3. Conditioned medium from CTGF/CCN2-treated AR42J cells induced chemotaxis in NR8383 macrophages and this response was abrogated in a dose dependent manner by addition of BX471, an inhibitor of chemokine (C-C motif) receptor 1. These results reveal that acinar CTGF/CCN2 plays a novel role in alcohol-induced inflammatory processes in the pancreas by increasing infiltration of macrophages and neutrophils and increasing acinar production of inflammatory mediators such as IL-1b or CCL3. The early production of CTGF/CCN2 by PAC to drive inflammation is distinct from its previously reported production by pancreatic stellate cells to drive fibrosis at later stages of pancreatic injury.

Model for generation of large numbers of primary, inflammatory skin-derived neutrophils, and macrophages

Tissue macrophages and inflammatory neutrophils represent important cells of the innate immune system responsible for various important tasks, i.e., elimination of pathogens and/or granuloma formation. Isolation of large numbers of primary phagocytes is vital for research with these cells. Within this protocol, we present a strategy for isolation of large numbers of inflammatory neutrophils and macrophages from murine skin that allows for follow-up in vivo or in vitro studies.

Dendritic cells in Leishmania major infections: mechanisms of parasite uptake, cell activation and evidence for physiological relevance

Leishmaniasis is one of the most important infectious diseases worldwide; a vaccine is still not available. Infected dendritic cells (DC) are critical for the initiation of protective Th1 immunity against Leishmania major. Phagocytosis of L. major by DC leads to cell activation, IL-12 release and (cross-) presentation of Leishmania antigens by DC. Here, we review the role of Fcγ receptor- and B cell-mediated processes for parasite internalization by DC. In addition, the early events after parasite inoculation that consist of mast cell activation, parasite uptake by skin-resident macrophages (MΦ), followed by neutrophil and monocyte immigration and DC activation are described. All these events contribute significantly to antigen processing in infected DC and influence resulting T cell priming in vivo. A detailed understanding of the role of DC for the development of efficient anti-Leishmania immunity will aid the development of potent anti-parasite drugs and/or vaccines.

The interaction between different types of activated RAW 264.7 cells and macrophage inflammatory protein-1 alpha

Background

Two major ways of macrophage (MΦ) activation can occur in radiation-induced pulmonary injury (RPI): classical and alternative MΦ activation, which play important roles in the pathogenesis of RPI. MΦ can produce chemokine MΦ inflammatory protein-1α (MIP-1α), while MIP-1α can recruit MΦ. The difference in the chemotactic ability of MIP-1α toward distinct activated MΦ is unclear. We speculated that there has been important interaction of MIP-1α with different activated MΦ, which might contribute to the pathogenesis of RPI.

Methods

Classically and alternatively activated MΦ were produced by stimulating murine MΦ cell line RAW 264.7 cells with three different stimuli (LPS, IL-4 and IL-13); Then we used recombinant MIP-1α to attract two types of activated MΦ. In addition, we measured the ability of two types of activated MΦ to produce MIP-1α at the protein or mRNA level.

Results

Chemotactic ability of recombinant MIP-1α toward IL-13-treated MΦ was the strongest, was moderate for IL-4-treated MΦ, and was weakest for LPS-stimulated MΦ (p < 0.01). The ability of LPS-stimulated MΦ to secrete MIP-1α was significantly stronger than that of IL-4-treated or IL-13-treated MΦ (p < 0.01). The ability of LPS-stimulated MΦ to express MIP-1α mRNA also was stronger than that of IL-4- or IL-13-stimulated MΦ (p < 0.01).

Conclusions

The chemotactic ability of MIP-1α toward alternatively activated MΦ (M2) was significantly greater than that for classically activated MΦ (M1). Meanwhile, both at the mRNA and protein level, the capacity of M1 to produce MIP-1α is better than that of M2. Thus, chemokine MIP-1α may play an important role in modulating the transition from radiation pneumonitis to pulmonary fibrosis in vivo, through the different chemotactic affinity for M1 and M2.

Mast cells and the development of allergic airway disease

Murine models have highlighted the importance of T-cells and T_H2 cytokines in development of allergen-induced airway disease. In contrast, the role of mast cells for the development of allergic airway disease has been controversial. Recent studies in murine models demonstrate a significant contribution of mast cells during the development of airway hyperresponsiveness and airway inflammation. Furthermore these models have allowed identifying certain mast cell-produced mediators (e.g. histamine and leukotriene B4) to be involved in the recruitment of effector T-cells into the lung. Additionally, mast cell-produced TNF can directly activate T_H2 cells and contribute to the development of allergic airway disease. These new findings demonstrate a complex role of mast cells and their mediators, not only as effector cells, but also during sensitization and development of allergic airway disease. Therefore mast cells and certain mast cell-produced mediators might be an interesting target for the prevention and treatment of allergic asthma.

A role for leukocyte-derived IL-1RA in DC homeostasis revealed by increased susceptibility of IL-1RA-deficient mice to cutaneous leishmaniasis

Dendritic cell (DC)-derived IL-1α/β plays a critical role in the induction of T helper type 1 (Th1)-dependent immunity against Leishmania. DCs from susceptible BALB/c mice produce less IL-1α/β when compared with resistant C57BL/6 mice, contributing to aberrant Th2 development and ultimate death of infected mice. We have extended our studies of the role of IL-1 in leishmaniasis using IL-1RA(-/-) BALB/c mice that are characterized by upregulated IL-1 receptor signaling. Unexpectedly, infection of IL-1RA(-/-) mice led to significantly worsened disease outcome with larger lesions, dramatically higher parasite burdens, and decreased IFN-γ production by antigen-specific T cells. We determined that IL-1RA(-/-) DCs were more mature already in the steady state, exhibited less phagocytotic capacity, and IL-12 production in response to various stimuli was impaired. Our data suggest that in addition to effects on Th education, IL-1α/β signaling also modulates DC homeostasis with increased signaling, leading to downmodulation of IL-12 synthesis and worsened disease outcome after infection with Leishmania major. Thus, the complex regulation of various members of the IL-1 cytokine family mediated through effects on both DCs and T cells critically contributes to disease outcome against this important human pathogen.