Role of macrophages in the pathogenesis of atopic dermatitis

Data-Independent Acquisition-Based Quantitative Proteomics Analysis Reveals Dynamic Network Profiles during the Macrophage Inflammatory Response

Understanding of the molecular regulatory mechanisms underlying the inflammatory response is incomplete. The present study focuses on characterizing the proteome in a model of inflammation in macrophages treated with lipopolysaccharide (LPS). A total of 3597 proteins are identified in macrophages with the data-independent acquisition (DIA) method. Bioinformatic analyses reveal discrete modules and the underlying molecular mechanisms, as well as the signaling network that modulates the development of inflammation. It is found that a total of 87 differentially expressed proteins are shared by all stages of LPS-induced inflammation in macrophages and that 18 of these proteins participate in metabolic processes by forming a tight interaction network. Data support the hypothesis that ribosome proteins play a key role in regulating the macrophage response to LPS. Interestingly, conjoint analyses of the transcriptome and proteome in macrophages treated with LPS reveal that the genes upregulated at both the mRNA and protein levels are mainly involved in inflammation and the immune response, whereas the genes downregulated are significantly enriched in metabolism-related processes. These results not only provide a more comprehensive understanding of the molecular mechanisms of inflammation mediated by bacterial infection but also provide a dynamic proteomic resource for further studies.

Intrauterine growth restriction induces skin inflammation, increases TSLP and impairs epidermal barrier function

Intrauterine growth restriction (IUGR) and low birth weight are risk factors for childhood asthma. Atopic march describes the progression from early dermatitis to asthma during life. Since inflammatory signaling is linked to increased airway resistance and lung remodeling in rats after IUGR, we queried if these findings are related to skin inflammatory response. Firstly, we induced IUGR in Wistar rats by isocaloric protein restriction during gestation. IUGR rats showed lower body weight at postnatal day 1 (P1), catch-up growth at P21, and similar body weight like controls at P90. At P1 and P90, mRNA of inflammatory as well as fibrotic markers and number of skin immune cells (macrophages) were increased after IUGR. Skin thymic stromal lymphopoietin (TSLP) mRNA at P1 and serum TSLP at P1 and P21 were elevated in IUGR. Moreover, IUGR impaired transepidermal water loss at P21 and P90. IUGR induced higher. Secondly, the increase of TEWL after Oxazolone treatment as a model of atopic dermatitis (AD) was greater in IUGR than in Co. Our data demonstrate an early inflammatory skin response, which is linked to persistent macrophage infiltration in the skin and impaired epidermal barrier function after IUGR. These findings coupled with elevated TSLP could underlie atopic diseases in rats after IUGR. KEY MESSAGES: • The present study shows that IUGR increases macrophage infiltration and induces an inflammatory and fibrotic gene expression pattern in the skin of newborn rats. • Early postnatal inflammatory response in the skin after IUGR is followed by impaired epidermal barrier function later in life. • IUGR aggravates transepidermal water loss in an experimental atopic dermatitis model, possibly through elevated TSLP in skin and serum. • Early anti-inflammatory treatment and targeting TSLP signaling could offer novel avenues for early prevention of atopic disorders and late asthma in high-risk infants.

Therapeutic Effects of Chinese Herbal Formula (PTQX) on NC/Nga Mice with Atopic Dermatitis-Like Skin Lesions

Atopic dermatitis (AD), also known as atopic eczema, is a chronic pruritic inflammatory skin disease. The available systemic therapies for atopic dermatitis are inadequate. Objective. This study aimed to evaluate the effects of the Chinese herbal formula Pei Tu Qing Xin (PTQX) on dermatitis severity and ear swelling, immunomodulation, and the infiltration of mast cells in a mouse model of 1-chloro-2,4-dinitrobenzene- (DNCB-) induced AD. Methods. AD-like symptoms were induced by DNCB in NC/Nga mice. Skin lesions, dermatitis, ear swelling, and scratching behaviour were evaluated. Changes in the T-helper type 1 (Th1), Th2, Th17, and regulatory T (Treg) subtypes and immunoregulation in the spleen and lymph nodes were detected by flow cytometry. Results. Histopathological and immunohistochemical analyses demonstrated that PTQX decreased the DNCB-mediated induction of mast cells and infiltration of inflammatory cells in the ear and dorsal skin. PTQX also reduced the DNCB-induced increase in the serum immunoglobulin E level, pruritus, and dermatitis (red, flaky areas) on the dorsal skin. Furthermore, PTQX regulated the balance between the populations of Th1, Th2, Th17, and Treg cells (particularly the latter two) in the lymph nodes. Conclusions. Our results suggest that the Chinese herbal formula PTQX can alleviate symptoms of AD, such as epithelial damage, redness, swelling, and pruritus, and potentially be used to treat this condition.

Topical Application of KAJD Attenuates 2,4-Dinitrochlorobenzene-Induced Atopic Dermatitis Symptoms Through Regulation of IgE and MAPK Pathways in BALB/C Mice and Several Immune Cell Types

Atopic dermatitis (AD) is a frequent skin complication that is caused by unknown reasons. KHU-ATO-JIN-D (KAJD) is a new drug aimed at AD composed of a mixture of extracts from six plants known to have anti-inflammatory and antiallergic effects. This study investigated whether KAJD alleviates 2,4-dinitrochlorobenzene (DNCB)-induced AD in BALB/c mice and several immune cell types. We applied KAJD to DNCB-induced AD-like skin lesions in BALB/c mice, phorbol myristate acetate/ionomycin-stimulated human mast cells (HMC-1), and lipopolysaccharide (LPS)-stimulated macrophages and splenocytes. Histological, ELISA, PCR, and Western blot experiments were performed. The application of KAJD significantly attenuated the lesion severity and skin thickness and inhibited the infiltration of inflammatory cells, mast cells, and CD4+ T cells into the sensitized skin of mice. Reduced leukocyte numbers and proinflammatory cytokine and IgE levels were also observed in the sera of KAJD-treated mice. Moreover, in vitro studies demonstrated that KAJD treatment reduced the LPS-induced expression of proinflammatory cytokines and nitric oxide (NO) production in RAW 264.7 cells. The regulation of IL-4 and IL-6 mRNA and MAPK pathways was also detected in agonist-induced isolated splenocytes and HMC-1 cells by the addition of KAJD. Taken together, our results demonstrate that KAJD inhibits the development of DNCB-induced AD in BALB/c mice and in several immune cell types, suggesting that KAJD might be a useful therapeutic drug for the treatment of AD.

Chitinase 3-like 1 drives allergic skin inflammation via Th2 immunity and M2 macrophage activation

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterized by defective skin barrier and Th2 immune responses. Chitinase 3-like 1 (CHI3L1), also known as breast regression protein 39 (BRP-39) in mice and human homologue YKL-40, plays important roles in Th2 inflammation and allergen sensitization. CHI3L1 has been implicated in a variety of diseases including asthma characterized by inflammation, apoptosis and tissue remodelling, but its role in AD remains elusive.

OBJECTIVE

The aim of this study was to investigate the role of CHI3L1 in the development and progression of AD.

RESULTS

We investigated YKL-40 levels in the serum and skin of AD patients by ELISA and immunofluorescence, respectively. Using a murine model of AD induced by ovalbumin (OVA), we investigated Th2 immune responses, M2 macrophage activation and skin barrier gene expression using wild-type (WT) and BRP-39 null mutant (BRP-39^-/- ) mice. YKL-40 level was significantly increased in serum of AD patients. In addition, both mRNA and protein expression levels of BRP-39 were higher in OVA-sensitized WT mice than in control mice. OVA-sensitized BRP-39^-/- mice showed decreased epidermal thickness, lower total serum IgE, Th2 cytokine levels and CD4⁺ effector T cell populations than OVA-sensitized WT mice. Induction of BRP-39 was dominant in dermal macrophages. BRP-39 deficiency was found to be involved in M2 macrophage activation. Consistently, the YKL-40 level in the skin of AD patients was higher than in normal subjects and it was expressed in dermal macrophages. BRP-39 deficiency attenuated dysregulation of skin barrier and tight junction genes.

CONCLUSIONS AND CLINICAL RELEVANCE

These findings demonstrate that CHI3L1 mediates the development of AD induced by OVA, affecting Th2 inflammation, M2 macrophage activation and skin barrier function.

Therapeutic Potential of Hematopoietic Prostaglandin D2 Synthase in Allergic Inflammation

Worldwide, there is a rise in the prevalence of allergic diseases, and novel efficient therapeutic approaches are still needed to alleviate disease burden. Prostaglandin D₂ (PGD₂) has emerged as a central inflammatory lipid mediator associated with increased migration, activation and survival of leukocytes in various allergy-associated disorders. In the periphery, the hematopoietic PGD synthase (hPGDS) acts downstream of the arachidonic acid/COX pathway catalysing the isomerisation of PGH₂ to PGD₂, which makes it an interesting target to treat allergic inflammation. Although much effort has been put into developing efficient hPGDS inhibitors, no compound has made it to the market yet, which indicates that more light needs to be shed on potential PGD₂ sources and targets to determine which particular condition and patient will benefit most and thereby improve therapeutic efficacy. In this review, we want to revisit current knowledge about hPGDS function, expression in allergy-associated cell types and their contribution to PGD₂ levels as well as beneficial effects of hPGDS inhibition in allergic asthma, rhinitis, atopic dermatitis, food allergy, gastrointestinal allergic disorders and anaphylaxis.

Unraveling the ECM-Immune Cell Crosstalk in Skin Diseases

The extracellular matrix (ECM) is a complex network of proteins and proteoglycans secreted by keratinocytes, fibroblasts and immune cells. The function of the skin ECM has expanded from being a scaffold that provides structural integrity, to a more dynamic entity that is constantly remodeled to maintain tissue homeostasis. The ECM functions as ligands for cell surface receptors such as integrins, dystroglycans, and toll-like receptors (TLRs) and regulate cellular signaling and immune cell dynamics. The ECM also acts as a sink for growth factors and cytokines, providing critical cues during epithelial morphogenesis. Dysregulation in the organization and deposition of ECMs lead to a plethora of pathophysiological conditions that are exacerbated by aberrant ECM-immune cell interactions. In this review, we focus on the interplay between ECM and immune cells in the context of skin diseases and also discuss state of the art therapies that target the key molecular players involved.

In silico approaches for enhancing retrieval analysis as a source for discovery of implant reactivity-related mechanisms and biomarkers

The ability to characterize implant debris in conjunction with corresponding immune and tissue-destructive responses renders retrieval analysis as an important tool for evaluating orthopedic devices. We applied advanced analytics and in silico approaches to illustrate the retrieval-based potential to elucidate host responses and enable discovery of corresponding biomarkers indicative of in vivo implant performance. Hip retrieval analysis was performed using variables based on immunostaining, polarized microscopy, and fretting-corrosion and oxidation analyses. Statistical analyses were performed in R. Hierarchical/k-means clustering and principal component analysis were used for data analysis and visualization. Correlation Engine (CE) and Ingenuity Pathway Analysis (IPA) were employed for in silico corroboration of putative biomarkers. Higher giant cell and histiocyte scores and positivity for CD68 and CD3 indicating infiltration with macrophages and T-cells, respectively, were detected mainly among older generation hips with higher ultra-high-molecular-weight-polyethylene loads. Our in silico analysis using pre-existing data on wear particle-induced loosening substantiated the role of CD68 in implant-induced innate responses and identified the CD68-related molecular signature that can be indicative of development of aseptic loosening and can be further corroborated for diagnostic/prognostic testing in clinical setting. Thus, this study confirmed the great potential of advanced analytics and in silico approaches for enhancing retrieval analysis applications to discovery of new biomarkers for optimizing implant-related preclinical testing and clinical management. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 108B:263-271, 2020.

Comparison of the Inhibitory Activities of 5,6-Dihydroergosterol Glycoside α- and β-Anomers on Skin Inflammation

Chronic skin inflammatory diseases, such as atopic dermatitis, are associated with a dysfunctional skin barrier due to an increase in various inflammatory stimuli, for instance inflammatory cytokines and chemokines. In particular, CCL17 and CCL22 expression is increased in patients with chronic skin inflammation. In this study, we synthesized several α- and β-anomers of dihydroergosterol (DHE)-glycosides and assessed their effects on CCL17 and CCL22 expression. We confirmed that the β-anomers of DHE-glycosides were superior to α-anomers of DHE-glycosides in inhibiting CCL17 and CCL22 mRNA and protein expression. In addition, we determined that DHE-glycoside β-anomers showed strong inhibitory activity towards pro-inflammatory cytokine mRNA and protein expression, including that of TNF-α, IL-6, and IL-1β- in stimulated HaCaT cells. These results imply that DHE-glycoside α- and β-anomers should be separated during synthesis of drugs for chronic skin inflammation. Our results also suggest that β-anomers of DHE-glycosides may play an important role as new drugs for chronic skin inflammation because of their ability to inhibit the skin inflammatory biomarker proteins CCL17 and CCL22.

Regulatory cells in the skin: Pathophysiologic role and potential targets for anti-inflammatory therapies

Inflammation is a fundamental defense mechanism to protect the body from danger, which becomes potentially harmful if it turns chronic. Therapeutic strategies aimed at specifically blocking proinflammatory signals, particularly cytokines, such as IL-4, IL-6, IL-13, IL-17A, or TNF-α, have substantially improved our ability to effectively and safely treat chronic inflammatory diseases. Much less effort has been made to better understand the role of potential anti-inflammatory mechanisms. Here we summarize the current understanding of regulatory cell populations in the context of chronic inflammation, namely macrophages, Langerhans cells, myeloid-derived suppressor cells, and regulatory T and B lymphocytes. Emphasis is given to the skin because many different immune-related diseases occur in the skin. Development, phenotype, function, and evidence for their role in animal models of inflammation, as well as in the corresponding human diseases, are described. Finally, the feasibility of using regulatory cells as targets for potentially disease-modifying therapeutic strategies is discussed.

Leveraging Multilayered "Omics" Data for Atopic Dermatitis: A Road Map to Precision Medicine

Atopic dermatitis (AD) is a complex multifactorial inflammatory skin disease that affects ~280 million people worldwide. About 85% of AD cases begin in childhood, a significant portion of which can persist into adulthood. Moreover, a typical progression of children with AD to food allergy, asthma or allergic rhinitis has been reported (“allergic march” or “atopic march”). AD comprises highly heterogeneous sub-phenotypes/endotypes resulting from complex interplay between intrinsic and extrinsic factors, such as environmental stimuli, and genetic factors regulating cutaneous functions (impaired barrier function, epidermal lipid, and protease abnormalities), immune functions and the microbiome. Though the roles of high-throughput “omics” integrations in defining endotypes are recognized, current analyses are primarily based on individual omics data and using binary clinical outcomes. Although individual omics analysis, such as genome-wide association studies (GWAS), can effectively map variants correlated with AD, the majority of the heritability and the functional relevance of discovered variants are not explained or known by the identified variants. The limited success of singular approaches underscores the need for holistic and integrated approaches to investigate complex phenotypes using trans-omics data integration strategies. Integrating omics layers (e.g., genome, epigenome, transcriptome, proteome, metabolome, lipidome, exposome, microbiome), which often have complementary and synergistic effects, might provide the opportunity to capture the flow of information underlying AD disease manifestation. Overlapping genes/candidates derived from multiple omics types include FLG, SPINK5, S100A8, and SERPINB3 in AD pathogenesis. Overlapping pathways include macrophage, endothelial cell and fibroblast activation pathways, in addition to well-known Th1/Th2 and NFkB activation pathways. Interestingly, there was more multi-omics overlap at the pathway level than gene level. Further analysis of multi-omics overlap at the tissue level showed that among 30 tissue types from the GTEx database, skin and esophagus were significantly enriched, indicating the biological interconnection between AD and food allergy. The present work explores multi-omics integration and provides new biological insights to better define the biological basis of AD etiology and confirm previously reported AD genes/pathways. In this context, we also discuss opportunities and challenges introduced by “big omics data” and their integration.

The Anaphylatoxin C3a Receptor Expression on Human M2 Macrophages Is Down-Regulated by Stimulating the Histamine H4 Receptor and the IL-4 Receptor

The anaphylatoxin C3a triggers inflammation by binding to its specific G-protein-coupled C3a receptor (C3aR). Since the number of C3aR, which is expressed on the cell surface, affects the response to C3a, we investigated the expression levels of C3aR on human M2 macrophages in allergic situations where high levels of the Th2 cytokine IL-4 and histamine are present in a local microenvironment. The histamine H1 receptor (H1R), H2R and the H4R mRNA expressions were induced or up-regulated during the differentiation process of M2 macrophages. The presence of histamine or agonists targeting the H1R, H2R and, in particular, the H4R during in vitro differentiation from monocytes to macrophages modified the M2 phenotype by regulating the macrophage differentiation marker CD68 and CD163 expressions. In -addition, the C3aR expression was also down-regulated by -ST-1006 during this process. Histamine and ST-1006 down-regulated the expression of C3aR with different time kinetics on fully differentiated M2 macrophages. By analysing C3a-induced IL-6 mRNA expression, we observed a diminished response to C3a in ST-1006-treated M2 macrophages when compared to un-treated cells. Expression of C3 was not affected by histamine, whereas IL-4 strongly down-regulated C3aR and C3 expressions. Our data suggests that down-regulation of C3aR expression by mediators present in allergic situations such as IL-4 or histamine has an anti-inflammatory impact by reducing the sensitivity to C3a-induced down-stream signaling, thereby contributing to the regulation of local inflammatory responses in the skin.

The histamine H4 receptor modulates the differentiation process of human monocyte-derived M1 macrophages and the release of CCL4/MIP-1β from fully differentiated M1 macrophages

OBJECTIVE

Histamine is an important mediator of biological functions and present in high amounts in inflammatory skin lesions which are characterised by a marked infiltration of myeloid derived cell populations. The aim of the study was to investigate the expression and function of histamine receptors, with a focus on the histamine H4 receptor (H4R) in detail during the differentiation process from monocytes to macrophages and on fully differentiated M1 macrophages.

METHODS

Quantitative PCR, ELISA technique, and flow cytometry were applied to analyze expression levels of histamine receptors, of CXCL10, CCL4, CCL3, or IL-23 and of the macrophage differentiation marker CD68, respectively.

RESULTS

We demonstrated that monocytes and fully differentiated M1 macrophages express H1R-, H2R-, and H4R mRNA which were differentially regulated during the differentiation process and in IFN-Ƴ and LPS classically activated M1 macrophages. The H3R mRNA was not expressed. During in vitro differentiation from monocytes to macrophages, the H4R agonist ST-1006 modified the M1 phenotype by up-regulating the macrophage differentiation marker CD68, by down-regulating the production of CXCL10, and by changing the morphology. In fully differentiated M1 macrophages, histamine or ST-1006 decreased the IFN-Ƴ- and LPS-induced CCL4 mRNA expression and protein production, whereas CCL3 or IL-23 production was not regulated via H4R.

CONCLUSIONS

We describe novel immunomodulatory functions of the H4R during the differentiation process of human monocyte-derived macrophages and in fully differentiated M1 macrophages. The down-regulation of Th1-related chemokines during the differentiation process or in classically activated macrophages via H4R may contribute to decreased migration of immune cells to the site of inflammation. This may have implications for the treatment of allergic diseases with H4R ligands regulating the dysbalance of Th2/Th1 polarizations in these disorders.

Targeting Intramembrane Protein-Protein Interactions: Novel Therapeutic Strategy of Millions Years Old

Intramembrane protein-protein interactions (PPIs) are involved in transmembrane signal transduction mediated by cell surface receptors and play an important role in health and disease. Recently, receptor-specific modulatory peptides rationally designed using a general platform of transmembrane signaling, the signaling chain homooligomerization (SCHOOL) model, have been proposed to therapeutically target these interactions in a variety of serious diseases with unmet needs including cancer, sepsis, arthritis, retinopathy, and thrombosis. These peptide drug candidates use ligand-independent mechanisms of action (SCHOOL mechanisms) and demonstrate potent efficacy in vitro and in vivo. Recent studies surprisingly revealed that in order to modify and/or escape the host immune response, human viruses use similar mechanisms and modulate cell surface receptors by targeting intramembrane PPIs in a ligand-independent manner. Here, I review these intriguing mechanistic similarities and discuss how the viral strategies optimized over a billion years of the coevolution of viruses and their hosts can help to revolutionize drug discovery science and develop new, disruptive therapies. Examples are given.

IL-4 driven transcription factor FoxQ1 is expressed by monocytes in atopic dermatitis and stimulates monocyte migration

Monocytes are actively recruited at sites of chronic inflammation. However, molecular factors involved in this process are not fully elucidated. Here, we show that cytokine IL-4 which is implicated in the development of chronic inflammatory disease atopic dermatitis (AD) induces expression of transcription factor FoxQ1 in human monocytes and macrophages. FoxQ1 mRNA levels were elevated in monocytes of AD patients compared to healthy donors. Overexpression of FoxQ1 in RAW 264.7 monocytic cells facilitated their migration towards MCP-1 and was associated with decreased expression of migration-regulating genes (claudin 11 and plexin C1). Furthermore, FoxQ1 overexpression in RAW cells accelerated TNFα secretion after LPS challenge. Overall, our results indicate that FoxQ1 stimulates monocyte motility, increases pro-inflammatory potential, and directs monocyte migration towards MCP-1 that is crucial for monocyte influx into inflammatory sites. This mechanism could contribute to the pathogenesis of chronic inflammatory disorders such as AD.

Refined Deep-Sea Water Suppresses Inflammatory Responses via the MAPK/AP-1 and NF-κB Signaling Pathway in LPS-Treated RAW 264.7 Macrophage Cells

Atopic dermatitis (AD) is a type of inflammatory skin disease caused by genetics, immune system dysfunction, and environmental stresses. It is, however, still considered to be a refractory disease. Macrophages are inflammatory immune cells that infiltrate the skin and induce inflammation. We investigated the effect of refined deep-sea water (RDSW) on lipopolysaccharide (LPS)-induced inflammatory response in RAW 264.7 macrophage cells. The results showed that RDSW suppressed the expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2. Furthermore, nitric oxide, a product of iNOS, and prostaglandin (PG) D₂ and PGE₂, products of COX-2, were significantly inhibited by RDSW in a hardness-dependent manner. Moreover, we found that RDSW reversed the release of histamines and regressed the mRNA expressions and production of pro-inflammatory cytokines, such as tumor necrosis factor-α, interleukin (IL)-1β, IL-6, and IL-10, and vascular endothelial growth factor, in a hardness-dependent manner. We also found that the suppressive effect of RDSW on LPS-induced inflammatory responses was regulated by the inhibition of NF-κB nuclear translocation, and ERK 1/2 and JNK 1/2 mediated the suppression of c-Jun and c-Fos expressions. In conclusion, the present investigation suggests the possibility that RDSW may be used to treat and/or prevent inflammatory diseases, including AD.

CD64: An Attractive Immunotherapeutic Target for M1-type Macrophage Mediated Chronic Inflammatory Diseases

To date, no curative therapy is available for the treatment of most chronic inflammatory diseases such as atopic dermatitis, rheumatoid arthritis, or autoimmune disorders. Current treatments require a lifetime supply for patients to alleviate clinical symptoms and are unable to stop the course of disease. In contrast, a new series of immunotherapeutic agents targeting the Fc γ receptor I (CD64) have emerged and demonstrated significant clinical potential to actually resolving chronic inflammation driven by M1-type dysregulated macrophages. This subpopulation plays a key role in the initiation and maintenance of a series of chronic diseases. The novel recombinant M1-specific immunotherapeutics offer the prospect of highly effective treatment strategies as they have been shown to selectively eliminate the disease-causing macrophage subpopulations. In this review, we provide a detailed summary of the data generated, together with the advantages and the clinical potential of CD64-based targeted therapies for the treatment of chronic inflammatory diseases.

Activation of the HMGB1‑TLR4‑NF‑κB pathway may occur in patients with atopic eczema

High mobility group protein B1 (HMGB1) has been reported to serve important roles in various pathological conditions. Toll‑like receptor 4 (TLR4), as one of the HMGB1 receptors, has been reported to be involved in the development of certain inflammatory diseases by activating nuclear factor NF‑κ‑B (NF‑κB). However, there are few studies investigating the effects of HMGB1, TLR4 and NF‑κB on human inflammatory dermatoses. In the present study, the distribution and characteristics of HMGB1, TLR4 and NF‑κB p65 expression in psoriasis and atopic eczema (AE) were investigated. In addition, immunohistochemical analysis was performed to evaluate their expression and distribution in normal skin, and in patients with AE or psoria-sis. Spearman's correlation analysis was used to predicate their relevancy. The present study identified that the p65 level in epithelial nuclei in AE skin was increased compared with normal and psoriasis skin (P<0.01). The level of extracellular HMGB1 in AE skin was also increased compared with normal and psoriasis skin (P<0.01). Meanwhile, TLR4 expression on the epithelial membranes of AE skin was increased compared with psoriasis skin (P<0.01). Furthermore, the level of extracellular HMGB1 was positively correlated with epithelial membrane TLR4 (r=0.3856; P<0.05) and epithelial nuclear p65 (r=0.5894; P<0.01) in AE skin. These results indicated that the HMGB1‑TLR4‑NF‑κB signaling pathway is activated in AE and may account for its pathogenesis, but not in psoriasis. Therefore, HMGB1, TLR4 and NF‑κB p65 have the potential to be targets for the treatment of human inflammatory dermatoses, including AE.

Immune modulation of some autoimmune diseases: the critical role of macrophages and neutrophils in the innate and adaptive immunity

Macrophages and neutrophils are key components involved in the regulation of numerous chronic inflammatory diseases, infectious disorders, and especially certain autoimmune disease. However, little is known regarding the contribution of these cells to the pathogenesis of autoimmune disorders. Recent studies have aimed to clarify certain important factors affecting the immunogenicity of these cells, including the type and dose of antigen, the microenvironment of the cell-antigen encounter, and the number, subset, and phenotype of these cells, which can prevent or induce autoimmune responses. This review highlights the role of macrophage subsets and neutrophils in injured tissues, supporting their cooperation during the pathogenesis of certain autoimmune diseases.

Clinical study and assessment of leukocyte phagocytic function in children with atopic dermatitis in Qassim region of Saudi Arabia

OBJECTIVE

Atopic dermatitis (AD) is a skin disorder clinically seen in the pediatric population. It is well recognized that patients with AD have an increased susceptibility to cutaneous colonization and infection with bacteria, fungi, and viruses. This study was undertaken to investigate the phagocytic activity and chemotactic response of mononuclear and polymorphonuclear leukocytes in severe AD patients.

METHODS

A total of 50 children with severe AD were selected according to severity scoring of AD (the SCORAD index) and 30 healthy children of same age and sex were also selected as controls. The mononuclear and neutrophilic leukocytes were separated and the phagocytic ingestion of zymosan particles was determined. Migration distance in response tobacterial lipopolysaccharide chemotactic factor was also determined. Immunological disturbance in AD patients was determined by sandwich enzyme-liked immunosorbent assays for total serum immunoglobulin E (IgE), complement 3 (C3) C4.

RESULTS

Of 50 AD patients with severe disease activity, 36 patients (72%) showed reduction in mononuclear and neutrophilic phagocytic activity. Children with AD had higher levels of total serum IgE, C3, and C4 compared to healthy children (P < 0.01).

CONCLUSIONS

The study results demonstrated an inhibition in the chemotactic response and phagocytic activity by mononuclear and/or neutrophilic leukocytes in severe AD patients. We further observed an involvement of perturb complement system in patients with AD. Hence, we clearly showed that AD is exacerbated with compromised immunological response, especially the innate immune response.

A mechanistic target of rapamycin complex 1/2 (mTORC1)/V-Akt murine thymoma viral oncogene homolog 1 (AKT1)/cathepsin H axis controls filaggrin expression and processing in skin, a novel mechanism for skin barrier disruption in patients with atopic dermatitis

BACKGROUND

Filaggrin, which is encoded by the filaggrin gene (FLG), is an important component of the skin's barrier to the external environment, and genetic defects in FLG strongly associate with atopic dermatitis (AD). However, not all patients with AD have FLG mutations.

OBJECTIVE

We hypothesized that these patients might possess other defects in filaggrin expression and processing contributing to barrier disruption and AD, and therefore we present novel therapeutic targets for this disease.

RESULTS

We describe the relationship between the mechanistic target of rapamycin complex 1/2 protein subunit regulatory associated protein of the MTOR complex 1 (RAPTOR), the serine/threonine kinase V-Akt murine thymoma viral oncogene homolog 1 (AKT1), and the protease cathepsin H (CTSH), for which we establish a role in filaggrin expression and processing. Increased RAPTOR levels correlated with decreased filaggrin expression in patients with AD. In keratinocyte cell cultures RAPTOR upregulation or AKT1 short hairpin RNA knockdown reduced expression of the protease CTSH. Skin of CTSH-deficient mice and CTSH short hairpin RNA knockdown keratinocytes showed reduced filaggrin processing, and the mouse had both impaired skin barrier function and a mild proinflammatory phenotype.

CONCLUSION

Our findings highlight a novel and potentially treatable signaling axis controlling filaggrin expression and processing that is defective in patients with AD.

Inhibitory Effect of Valencene on the Development of Atopic Dermatitis-Like Skin Lesions in NC/Nga Mice

Valencene (VAL) isolated from Cyperus rotundus possesses various biological effects such as antiallergic and antimelanogenesis activity. We investigated the effect of VAL on atopic dermatitis (AD) skin lesions and their molecular mechanisms. We topically applied VAL to 1-chloro-2,4-dinitrobenzene (DNCB) sensitized NC/Nga mice. Modified scoring atopic dermatitis index, scratching behavior, and histological/immunohistochemical staining were used to monitor disease severity. RT-PCR, western blotting, and enzyme-linked immunosorbent assay were used to determine the level of IgE, proinflammatory cytokines/chemokines production, and skin barrier proteins expression. Topical application of VAL significantly reduced AD-like symptoms and recovered decreased expression of filaggrin in DNCB-sensitized NC/Nga mice. The levels of serum IgE, IL-1β, IL-6, and IL-13 in skin/splenic tissue were reduced. In vitro studies using TNF-α and IFN-γ treated HaCaT cells revealed that VAL inhibited the exaggerated expression of Th2 chemokines including TARC/CCL17, MDC/CCL22, and proinflammatory chemokines such as CXCL8, GM-CSF, and I-CAM through blockade of the NF-κB pathway. In addition, expression of the skin barrier protein, involucrin, was also increased by VAL treatment. VAL inhibited the production and expression of proinflammatory cytokines IL-1β and IL-6 in LPS-stimulated RAW 264.7 cells. These results suggest that VAL may serve as a potential therapeutic option for AD.

Evaluation of cytotoxicity and inflammatory activity of wastewater collected from a textile factory before and after treatment by coagulation-flocculation methods

Effective treatment of textile effluent prior to discharge is necessary in order to avert the associated adverse health impacts on human and aquatic life. In the present investigation, coagulation/flocculation processes were evaluated for the effectiveness of the individual treatment. Effectiveness of the treatment was evaluated based on the physicochemical characteristics. The quality of the pre-treated and post-flocculation treated effluent was further evaluated by determination of cytotoxicity and inflammatory activity using RAW264.7 cell cultures. Cytotoxicity was determined using WST-1 assay. Nitric oxide (NO) and interleukin 6 (IL-6) were used as biomarkers of inflammation. NO was determined in cell culture supernatant using the Griess reaction assay. The IL-6 secretion was determined using double antibody sandwich enzyme linked immunoassay (DAS ELISA). Cytotoxicity results show that raw effluent reduced the cell viability significantly (P < 0.001) compared to the negative control. All effluent samples treated by coagulation/flocculation processes at 1 in 100 dilutions had no cytotoxic effects on RAW264.7 cells. The results on inflammatory activities show that the raw effluent and effluent treated with 1.6 g/L of Fe-Mn oxide induced significantly (P < 0.001) higher NO production than the negative control. The inflammatory results further show that the raw effluent induced significantly (P < 0.001) higher production of IL-6 than the negative control. Among the coagulants/flocculants evaluated Al2(SO4)3.14H2O at a dosage of 1.6 g/L was the most effective to remove both toxic and inflammatory pollutants. In conclusion, the inflammatory responses in RAW264.7 cells can be used as sensitive biomarkers for monitoring the effectiveness of coagulation/flocculation processes used for textile effluent treatment.

A newly synthesized macakurzin C-derivative attenuates acute and chronic skin inflammation: The Nrf2/heme oxygenase signaling as a potential target

Impaired immune responses in skin play a pivotal role in the development and progression of chemical-associated inflammatory skin disorders. In this study, we synthesized new flavonoid derivatives from macakurzin C, and identified in vitro and in vivo efficacy of a potent anti-inflammatory flavonoid, Compound 14 (CPD 14), with its underlying mechanisms. In lipopolysaccharide (LPS)-stimulated murine macrophages and IFN-γ/TNF-α-stimulated human keratinocytes, CPD 14 significantly inhibited the release of inflammatory mediators including nitric oxide (NO), prostaglandins, and cytokines (IC50 for NO inhibition in macrophages: 4.61μM). Attenuated NF-κB signaling and activated Nrf2/HO-1 pathway were responsible for the anti-inflammatory effects of CPD 14. The in vivo relevance was examined in phorbol 12-myristate 13-acetate (TPA)-induced acute skin inflammation and oxazolone-induced atopic dermatitis models. Topically applied CPD 14 significantly protected both irritation- and sensitization-associated skin inflammation by suppressing the expression of inflammatory mediators. In summary, we demonstrated that a newly synthesized flavonoid, CPD 14, has potent inhibitory effects on skin inflammation, suggesting it is a potential therapeutic candidate to treat skin disorders associated with excessive inflammation.

LILRA6 copy number variation correlates with susceptibility to atopic dermatitis

Leukocyte immunoglobulin-like receptors (LILR) are expressed mostly on myelomonocytic cells where they are mediators of immunological tolerance. Two LILR genes, LILRA3 and LILRA6, exhibit marked copy number variation. We assessed the contribution of these genes to atopic dermatitis (AD) by analysing transmission in 378 AD families. The data indicated that copies of LILRA6 were over-transmitted to affected patients. They are consistent with a contribution of LILR genes to AD. They could affect the equilibrium between activating and inhibitory signals in the immune response.

Anti-Inflammatory Effect of 3-Bromo-4,5-Dihydroxybenzaldehyde, a Component of Polysiphonia morrowii, In Vivo and In Vitro

3-Bromo-4,5-dihydroxybenzaldehyde (BDB) is a natural bromophenol compound that is most commonly isolated from red algae. The present study was designed to investigate the anti-inflammatory properties of BDB on atopic dermatitis (AD) in mice induced by 2,4-dinitrochlorobenzene (DNCB) and on lipopolysaccharide (LPS)-stimulated murine macrophages. BDB treatment (100 mg/kg) resulted in suppression of the development of AD symptoms compared with the control treatment (induction-only), as demonstrated by reduced immunoglobulin E levels in serum, smaller lymph nodes with reduced thickness and length, a decrease in ear edema, and reduced levels of inflammatory cell infiltration in the ears. In RAW 264.7 murine macrophages, BDB (12.5, 25, 50, and 100 μM) suppressed the production of interleukin-6, a proinflammatory cytokine, in a dose-dependent manner. BDB also had an inhibitory effect on the phosphorylation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and signal transducer and activator of transcription 1 (STAT1; Tyr 701), two major signaling molecules involved in cellular inflammation. Taken together, the results show that BDB treatment alleviates inflammatory responses in an atopic dermatitis mouse model and RAW 264.7 macrophages. These results suggest that BDB may be a useful therapeutic strategy for treating conditions involving allergic inflammation such as atopic dermatitis.

Macrophage responses to implants: prospects for personalized medicine

Implants, transplants, and implantable biomedical devices are mainstream solutions for a wide variety of human pathologies. One of the persistent problems around nondegradable metallic and polymeric implants is failure of macrophages to resolve the inflammation and their tendency to stay in a state, named "frustrated phagocytosis." During the initial phase, proinflammatory macrophages induce acute reactions to trauma and foreign materials, whereas tolerogenic anti-inflammatory macrophages control resolution of inflammation and induce the subsequent healing stage. However, implanted materials can induce a mixed pro/anti-inflammatory phenotype, supporting chronic inflammatory reactions accompanied by microbial contamination and resulting in implant failure. Several materials based on natural polymers for improved interaction with host tissue or surfaces that release anti-inflammatory drugs/bioactive agents have been developed for implant coating to reduce implant rejection. However, no definitive, long-term solution to avoid adverse immune responses to the implanted materials is available to date. The prevention of implant-associated infections or chronic inflammation by manipulating the macrophage phenotype is a promising strategy to improve implant acceptance. The immunomodulatory properties of currently available implant coatings need to be improved to develop personalized therapeutic solutions. Human primary macrophages exposed to the implantable materials ex vivo can be used to predict the individual's reactions and allow selection of an optimal coating composition. Our review describes current understanding of the mechanisms of macrophage interactions with implantable materials and outlines the prospects for use of human primary macrophages for diagnostic and therapeutic approaches to personalized implant therapy.

Sceptridium ternatum attenuates allergic contact dermatitis-like skin lesions by inhibiting T helper 2-type immune responses and inflammatory responses in a mouse model

BACKGROUND

Sceptridium ternatum (ST) is a medicinal herb used in folk remedies for the treatment of various disorders such as pertussis, allergic asthma, abdominalgia, diarrhea, and external use for wound healing. However, the biological and pharmacological activities of ST are not fully clarified besides anti-asthmatic effect.

OBJECTIVE

We studied a Sceptridium ternatum ethanol extract (ST) with respect to its anti-inflammatory and immune regulatory activities in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells, concanavalin A (conA)-stimulated BALB/c mice splenocytes, and a 2,4-dinitrochlorobenzene (DNCB)-induced allergic contact dermatitis (ACD) mouse model.

METHODS

RAW 264.7 cells were pretreated with ST for 1h and then stimulated with LPS. To determine the anti-inflammatory effects of ST, the production of nitric oxide (NO), interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) were measured using an enzyme-linked immunosorbent assay (ELISA). To determine its anti-allergic effects, splenocytes from BALB/c mice were incubated and stimulated with conA in the absence or presence of ST for 48h. The production of IL-4 and interferon (IFN)-γ in culture supernatants were evaluated by ELISA. To test the effects of ST on ACD, 100μL of 1% DNCB was applied to the dorsal skin of BALB/c mice for 2 weeks, and ST was administered 2 h before DNCB application. The thicknesses of the epidermis and dermis were determined by skin histological analysis. Serum immunoglobulin (Ig) E levels, the production of IL-1β, IL-4, and IL-6 in dorsal skin tissue, and T helper (Th) 2 cytokines production of CD4(+) T cells were analyzed by ELISA. The expression of nuclear transcription factor-κB (NF-κB) both in vitro and in vivo was determined via immunoblotting.

RESULTS

In RAW 264.7 cells, ST inhibited LPS-induced inflammation mediator production and NF-κB expression. ST upregulated IFN-γ production and downregulated IL-4 production in conA-stimulated splenocytes. ST application reduced the thicknesses of the epidermis and dermis by decreasing serum IgE level and the expressions of IL-1β, IL-4, IL-6, and NF-κB in the dorsal skin of the DNCB-induced ACD model mice. Furthermore, ST treated group showed reduction of the Th2 cytokines production in activated CD4(+) T cells.

CONCLUSION

These findings not only indicate that application of ST reduced skin thickening by regulating Th 2-type allergic responses and inhibiting expression of inflammatory mediators in a DNCB-induced ACD mouse model, but also suggest that Sceptridium ternatum is a natural option for the treatment of skin inflammation.

Effect of topical application of quercetin-3-O-(2″-gallate)-α-l-rhamnopyranoside on atopic dermatitis in NC/Nga mice

BACKGROUND

Quercetin-3-O-(2″-gallate)-α-l-rhamnopyranoside (QGR) is a new quercetin derivative which is isolated from the leaves of Acer ginnala Maxim, a native plant of Korea. Quercetin has several biological effects including antioxidative, anti-inflammatory, and anti-allergic effects. However, the topical effect of QGR on atopic dermatitis (AD) like skin lesion in NC/Nga mice has not been studied.

OBJECTIVE

To evaluate the anti-inflammatory and anti-allergic effect of QGR in a murine model of atopic dermatitis.

METHODS

We measured inducible nitric oxide synthase (iNOS) and cyclooxygenase -2(COX-2) level in RAW264.7 cell with QGR treatment. And after induction of AD like skin lesions with Dermatophagoides farina (Df) ointment, mice were treated with QGR and control drugs. Clinical scores, interleukin (IL) 4, 5, and 13, serum IgE, eosinophil levels, iNOS and COX-2 level were evaluated.

RESULTS

Results show that mRNA level of iNOS and COX-2 in vitro were decreased after QGR treatment. Topical QGR markedly decreased the iNOS and COX-2 mRNA expressions in the skin. QGR also significantly suppressed the increase in the level of total plasma IgE and eosinophils. In addition, topical application of QGR down-regulated the expressions of the cytokines, IL-4,5 and 13, which were induced by Df ointment stimulation.

CONCLUSIONS

In the present study, we showed that topical application of QGR ameliorated Df-induced AD-like inflammatory responses in NC/Nga mice. These results demonstrate that QGR might be beneficial in the treatment of AD.

An emulsion restores the skin barrier by decreasing the skin pH and inflammation in a canine experimental model

The aim of this study was to investigate the effect of Douxo(®) Calm Mousse (Sogeval, Laval, France) on restoration of the skin barrier in a canine model of barrier disruption. Tape strips were performed, daily for 6 days, on the lateral thorax of five healthy beagle dogs. Douxo(®) Calm Mousse was applied daily for 5 days to one side of the thorax and the opposite side was left untreated. The effects of treatment were evaluated by measurement of transepidermal water loss (TEWL) and pH and by histological assessment of disrupted skin at various times during barrier repair. Although no effect on TEWL was observed, Douxo(®) Calm Mousse maintained an acidic pH after three applications and reduced skin inflammation, which was most pronounced after five applications. The results of the study suggest that Douxo(®) Calm Mousse exerts a beneficial effect on barrier restoration and on markers of inflammation.

Asian dust particles induce macrophage inflammatory responses via mitogen-activated protein kinase activation and reactive oxygen species production

Asian dust is a springtime meteorological phenomenon that originates in the deserts of China and Mongolia. The dust is carried by prevailing winds across East Asia where it causes serious health problems. Most of the information available on the impact of Asian dust on human health is based on epidemiological investigations, so from a biological standpoint little is known of its effects. To clarify the effects of Asian dust on human health, it is essential to assess inflammatory responses to the dust and to evaluate the involvement of these responses in the pathogenesis or aggravation of disease. Here, we investigated the induction of inflammatory responses by Asian dust particles in macrophages. Treatment with Asian dust particles induced greater production of inflammatory cytokines interleukin-6 and tumor necrosis factor-α (TNF-α) compared with treatment with soil dust. Furthermore, a soil dust sample containing only particles ≤10 μm in diameter provoked a greater inflammatory response than soil dust samples containing particles >10 μm. In addition, Asian dust particles-induced TNF-α production was dependent on endocytosis, the production of reactive oxygen species, and the activation of nuclear factor-κB and mitogen-activated protein kinases. Together, these results suggest that Asian dust particles induce inflammatory disease through the activation of macrophages.