Differential expression of thymus- and activation-regulated chemokine (CCL17) and macrophage-derived chemokine (CCL22) by human fibroblasts from cornea, skin, and lung

Downstream STING pathways IRF3 and NF-κB differentially regulate CCL22 in response to cytosolic dsDNA

Double-stranded DNA (dsDNA) in the cytoplasm of eukaryotic cells is abnormal and typically indicates the presence of pathogens or mislocalized self-DNA. Multiple sensors detect cytosolic dsDNA and trigger robust immune responses via activation of type I interferons. Several cancer immunotherapy treatments also activate cytosolic nucleic acid sensing pathways, including oncolytic viruses, nucleic acid-based cancer vaccines, and pharmacological agonists. We report here that cytosolic dsDNA introduced into malignant cells can robustly upregulate expression of CCL22, a chemokine responsible for the recruitment of regulatory T cells (Tregs). Tregs in the tumor microenvironment are thought to repress anti-tumor immune responses and contribute to tumor immune evasion. Surprisingly, we found that CCL22 upregulation by dsDNA was mediated primarily by interferon regulatory factor 3 (IRF3), a key transcription factor that activates type I interferons. This finding was unexpected given previous reports that type I interferon alpha (IFN-α) inhibits CCL22 and that IRF3 is associated with strong anti-tumor immune responses, not Treg recruitment. We also found that CCL22 upregulation by dsDNA occurred concurrently with type I interferon beta (IFN-β) upregulation. IRF3 is one of two transcription factors downstream of the STimulator of INterferon Genes (STING), a hub adaptor protein through which multiple dsDNA sensors transmit their signals. The other transcription factor downstream of STING, NF-κB, has been reported to regulate CCL22 expression in other contexts, and NF-κB has also been associated with multiple pro-tumor functions, including Treg recruitment. However, we found that NF-κB in the context of activation by cytosolic dsDNA contributed minimally to CCL22 upregulation compared with IRF3. Lastly, we observed that two strains of the same cell line differed profoundly in their capacity to upregulate CCL22 and IFN-β in response to dsDNA, despite apparent STING activation in both cell lines. This finding suggests that during tumor evolution, cells can acquire, or lose, the ability to upregulate CCL22. This study adds to our understanding of factors that may modulate immune activation in response to cytosolic DNA and has implications for immunotherapy strategies that activate DNA sensing pathways in cancer cells.

Role of Damage-Associated Molecular Patterns (DAMPs/Alarmins) in Severe Ocular Allergic Diseases

Severe ocular allergic diseases, such as atopic keratoconjunctivitis and vernal keratoconjunctivitis, cause severe allergic inflammation in the conjunctiva and corneal epithelial damage, resulting in visual disturbances. The involvement of damage (danger)-associated molecular patterns (DAMPs/alarmins) in the pathogenesis of these diseases has been recognized. Alarmins released from damaged corneal epithelial cells or eosinophils play a critical role in the induction of corneal lesions, vicious loop of corneal injury, and exacerbation of conjunctival allergic inflammation. Alarmins in the conjunctiva also play an essential role in the development of both allergic inflammation, based on the acquired immune system, and type 2 inflammation by innate immune responses in the ocular surface. Therefore, alarmins may be a potentially important therapeutic target in severe refractory ocular allergic diseases.

Promotion of conjunctival fibroblast-mediated collagen gel contraction by mast cells through up-regulation of matrix metalloproteinase release and activation

Mast cells and conjunctival fibroblasts contribute to conjunctival wound healing and allergic ocular inflammation. The number of mast cells in the conjunctiva is increased in individuals with cicatricial fibrosis-causing ocular surface diseases and after glaucoma filtering surgery, suggesting that these cells may contribute to the scarring observed after such surgery. We studied the potential mechanism of fibroblast-mast cell interaction in the healing of conjunctival wounds using a three-dimensional collagen gel culture system. We found that mast cells derived from the bone marrow of mice embedded in a collagen gel did not induce gel contraction. However, an increase in mast cells was associated with increased collagen gel contraction mediated by mouse conjunctival fibroblasts. The extent of collagen degradation was not affected by the co-culture of mast cells and conjunctival fibroblasts. Gelatin zymography disclosed that mast cells increased the amounts of both the pro form of matrix metalloproteinase (MMP)-9 and the active form of MMP-2 in supernatants of conjunctival fibroblast cultures. Furthermore, the potentiating effect of mast cells on contraction of the collagen gel through conjunctival fibroblasts was attenuated by the addition of a synthetic MMP inhibitor. Thus, current results suggest that mast cells accelerate the conjunctival fibroblast-dependent contraction of collagen gel by increasing the release as well as activation of MMPs. Therefore, the interaction between mast cells and conjunctival fibroblasts may contribute to conjunctival scar formation after glaucoma filtering surgery.

Deoxynivalenol and zearalenone: Different mycotoxins with different toxic effects in donkey (Equus asinus) endometrial epithelial cells

Deoxynivalenol (DON) and zearalenone (ZEA), which are commonly found in feed products, exhibit serious negative effects on the reproductive systems of domestic animals. However, the toxicity of mycotoxins on the uterine function of donkey (Equus asinus) remains unclear. This study investigated the biological effects of DON and ZEA exposure on donkey endometrial epithelial cells (EECs). It was administered 10 μM and 30 μM DON and ZEA to cells cultured in vitro. The results showed that 10 μM DON exposure markedly changed the expression levels of pyroptosis-associated genes and that 30 μM ZEA exposure changed the expression levels of inflammation-associated genes in EECs. The mRNA expression of cancer-promoting genes was markedly upregulated in cells exposed to DON and 30 μM ZEA; in particular, 10 μM and 30 μM DON and ZEA markedly disturbed the expression of androgen and estrogen secretion-related genes. Furthermore, Q-PCR, Western blot, and immunofluorescence analyses verified the different expression patterns of related genes in DON- and ZEA-exposed EECs. Collectively, these results illustrated the impact of exposure to different toxins and concrete toxicity on the mRNA expression of EECs from donkey in vitro.

Repeated exposure of house dust mite induces progressive airway inflammation in mice: Differential roles of CCL17 and IL-13

We conducted a systematic evaluation of lung inflammation indued by repeated intranasal exposure (for 10 consecutive days) to a human aeroallergen, house dust mite (HDM) in BALB/c mice. Peak influx of neutrophils, monocytes/lymphocytes, and eosinophils was observed in bronchoalveolar lavage (BAL) on days 1, 7 and 11, respectively, and normalized to baseline by day 21. Peak elevations of Th2, myeloid-derived cytokines/chemokines and serum IgE were seen both in BAL and lung tissue homogenates between days 7 and 11, and declined thereafter; however, IL-33 levels remained elevated from day 7 to day 21. Airway hyperreactivity to inhaled methacholine was significantly increased by day 11 and decreased to baseline by day 21. The lung tissue showed perivascular and peribronchial cuffing, epithelial hypertrophy and hyperplasia and goblet cell formation in airways by day 11, and resolution by day 21. Levels of soluble collagen and tissue inhibitors of metalloproteinases (TIMP) also increased reflecting tissue remodeling in the lung. Microarray analysis demonstrated a significant time-dependent up-regulation of several genes including IL-33, CLCA3, CCL17, CD4, CD10, CD27, IL-13, Foxa3, IL-4, IL-10, and CD19, in BAL cells as well as the lung. Pre-treatment of HDM challenged mice with CCL17 and IL-13 antibodies reduced BAL cellularity, airway hyper-responsiveness (AHR), and histopathological changes. Notably, anti-IL-13, but not anti-CCL17 monoclonal antibodies (mAbs) reduced BAL neutrophilia while both mAbs attenuated eosinophilia. These results suggest that CCL17 has an overlapping, yet distinct profile versus IL-13 in the HDM model of pulmonary inflammation and potential for CCL17-based therapeutics in treating Th2 inflammation.

Corneal fibroblasts: Function and markers

Corneal stromal keratocytes contribute to the maintenance of corneal transparency and shape by synthesizing and degrading extracellular matrix. They are quiescent in the healthy cornea, but they become activated in response to insults from the external environment that breach the corneal epithelium, with such activation being associated with phenotypic transformation into fibroblasts. Corneal fibroblasts (activated keratocytes) act as sentinel cells to sense various external stimuli-including damage-associated molecular patterns derived from injured cells, pathogen-associated molecular patterns of infectious microorganisms, and inflammatory mediators such as cytokines-under pathological conditions such as trauma, infection, and allergy. The expression of various chemokines and adhesion molecules by corneal fibroblasts determines the selective recruitment and activation of inflammatory cells in a manner dependent on the type of insult. In infectious keratitis, the interaction of corneal fibroblasts with various components of microbes and with cytokines derived from infiltrated inflammatory cells results in excessive degradation of stromal collagen and consequent corneal ulceration. Corneal fibroblasts distinguish between type 1 and type 2 inflammation through recognition of corresponding cytokines, with their activation by type 2 cytokines contributing to the pathogenesis of corneal lesions in severe ocular allergic diseases. Pharmacological targeting of corneal fibroblast function is thus a potential novel therapeutic approach to prevention of excessive corneal stromal inflammation, damage, and scarring.

Japanese guidelines for allergic conjunctival diseases 2020

The definition, classification, pathogenesis, test methods, clinical findings, criteria for diagnosis, and therapies of allergic conjunctival disease are summarized based on the Guidelines for Clinical Management of Allergic Conjunctival Disease 2019. Allergic conjunctival disease is defined as "a conjunctival inflammatory disease associated with a Type I allergy accompanied by some subjective or objective symptoms." Allergic conjunctival disease is classified into allergic conjunctivitis, atopic keratoconjunctivitis, vernal keratoconjunctivitis, and giant papillary conjunctivitis. Representative subjective symptoms include ocular itching, hyperemia, and lacrimation, whereas objective symptoms include conjunctival hyperemia, swelling, folliculosis, and papillae. Patients with vernal keratoconjunctivitis, which is characterized by conjunctival proliferative changes called giant papilla accompanied by varying extents of corneal lesion, such as corneal erosion and shield ulcer, complain of foreign body sensation, ocular pain, and photophobia. In the diagnosis of allergic conjunctival diseases, it is required that type I allergic diathesis is present, along with subjective and objective symptoms accompanying allergic inflammation. The diagnosis is ensured by proving a type I allergic reaction in the conjunctiva. Given that the first-line drug for the treatment of allergic conjunctival disease is an antiallergic eye drop, a steroid eye drop will be selected in accordance with the severity. In the treatment of vernal keratoconjunctivitis, an immunosuppressive eye drop will be concomitantly used with the abovementioned drugs.

Local allergic conjunctivitis: a phenotype of allergic conjunctivitis

PURPOSE

Local allergic rhinitis (LAR) has been reported in the field of otolaryngology; however, the concept of local allergic conjunctivitis (LAC) has not been widely studied in the ophthalmologic community. We routinely examined total IgE levels in tear fluids (t-tIgE) and antigen-specific IgE levels in serum (s-sIgE) in patients with suspected allergic conjunctivitis, on the basis of Japanese guidelines for allergic conjunctival diseases. There are several cases in which the results of t-tIgE and s-sIgE testing are divergent. We suggest that these divergent cases correspond to LAR in otolaryngology.

METHODS

The study included 148 patients (33 men and 115 women) with clinical symptoms and signs of allergic conjunctivitis. Allerwatch Tear IgE^® was used for measurement of t-tIgE levels. ImmunoCAP Rapid^® and View Allergy 39^® were used for measurement of s-sIgE levels. Conjunctival cytology using spatula was used to identify eosinophils on the conjunctiva.

RESULTS

A total of 83 patients (56.1%) were positive and 65 patients were negative for t-tIgE in the AW. In the ICR, 97 patients (65.5%) were positive for at least one of the eight allergens, whereas 51 (34.5%) were negative for all allergens. Among 83 patients positive for t-tIgE, 14 (16.9%) had no detectable s-sIgE. Therefore, we considered the possibility of LAC in cases in which only local IgE could be detected. Among 28 cases (18.9%) who were negative for t-tIgE and s-sIgE, 21 underwent conjunctival scraping; eosinophils were found in four cases and eosinophilic granules in two. Accordingly, we considered the possibility of non-IgE-type AC in these six cases.

CONCLUSIONS

These results suggest the existence of LAC that is a candidate of a phenotype of AC.

Adult T-Cell Leukemia/Lymphoma-Related Ocular Manifestations: Analysis of the First Large-Scale Nationwide Survey

Adult T-cell leukemia/lymphoma (ATL) is a rare and aggressive T-cell malignancy with a high mortality rate, resulting in a lack of information among ophthalmologists. Here, we investigated the state of ophthalmic medical care for ATL and ATL-related ocular manifestations by conducting the first large-scale nationwide survey in Japan. A total of 115 facilities were surveyed, including all university hospitals in Japan that were members of the Japanese Ophthalmological Society and regional core facilities that were members of the Japanese Ocular Inflammation Society. The collected nationwide data on the state of medical care for ATL-related ocular manifestations and ATL-associated ocular findings were categorized, tallied, and analyzed. Of the 115 facilities, 69 (60%) responded. Overall, 28 facilities (43.0%) had experience in providing ophthalmic care to ATL patients. ATL-related ocular manifestations were most commonly diagnosed “based on blood tests and characteristic ophthalmic findings.” By analyzing the 48 reported cases of ATL-related ocular manifestations, common ATL-related ocular lesions were intraocular infiltration (22 cases, 45.8%) and opportunistic infections (19 cases, 39.6%). All cases of opportunistic infection were cytomegalovirus retinitis. Dry eye (3 cases, 6.3%), scleritis (2 cases, 4.2%), uveitis (1 case, 2.1%), and anemic retinopathy (1 case, 2.1%) were also seen. In conclusion, intraocular infiltration and cytomegalovirus retinitis are common among ATL patients, and ophthalmologists should keep these findings in mind in their practice.

NK-4 exerts selective regulatory effects on the activation and function of allergy-related Th2 cells

NK-4 is the main component of the antiallergic drug Lumin, which has been in popular usage since the early 1950s. In this study, we examined whether NK-4 exerts a regulatory effect on the activation and effector function of Th2 cells. NK-4 inhibited IL-4 production by anti-CD3ε mAb-stimulated BALB/c mouse spleen cells, whereas NK-4 had little effect on IFN-γ production. IL-4 and IL-5 secretion by anti-CD3ε mAb- or antigen-stimulated Th2 cells (D10.G4.1) was abrogated by NK-4 without affecting cell numbers, whereas IFN-γ secretion by activated Th1 cells was unchanged. Mechanistic analysis revealed that NK-4 inhibited mRNA expression of the Th2-associated transcription factors GATA-3 and NFATc1 in anti-CD3ε mAb-stimulated D10.G4.1 cells. Regarding the regulation of Th2 cell effector functions, NK-4 inhibited the secretion of eotaxin and thymus and activation-regulated chemokine (TARC) by normal human dermal fibroblasts in response to IL-4 and/or TNF-α. NK-4 achieved TARC attenuation comparable to what is observed with suplatast tosilate, an antiallergic drug that selectively inhibits Th2 cytokine production, at 14-fold lower concentrations of suplatast tosilate. Dexamethasone increased TARC production by 2.2- to 2.6-fold of control cultures. NK-4 successfully inhibited the STAT6 signaling pathway, suggesting a potential mechanism for down-regulating chemokines expression. In addition, NK-4 abrogated IL-4-driven modulation of cytokine production profile in human monocytic THP-1 cells from proinflammatory to anti-inflammatory response, as seen in the inverted ratio of TNF-α to IL-10 produced in response to LPS. These results suggest that NK-4 could prevent IL-4-driven polarization to alternatively activated macrophages, which are proposed to have pathogenic roles in allergic asthma. The importance of Th2 cytokines and chemokines in the development and progression of type 2 inflammatory disorders has been highlighted by recent advance in our understanding the immunological mechanism underlying allergic disease. Our results support the use of NK-4 as a reasonable therapeutic option to alleviate Th2-mediated allergic inflammation.

Corneal Fibroblasts as Sentinel Cells and Local Immune Modulators in Infectious Keratitis

The cornea serves as a barrier to protect the eye against external insults including microbial pathogens and antigens. Bacterial infection of the cornea often results in corneal melting and scarring that can lead to severe visual impairment. Not only live bacteria but also their components such as lipopolysaccharide (LPS) of Gram-negative bacteria contribute to the development of inflammation and subsequent corneal damage in infectious keratitis. We describe the important role played by corneal stromal fibroblasts (activated keratocytes) as sentinel cells, immune modulators, and effector cells in infectious keratitis. Corneal fibroblasts sense bacterial infection through Toll-like receptor (TLR)–mediated detection of a complex of LPS with soluble cluster of differentiation 14 (CD14) and LPS binding protein present in tear fluid. The cells then initiate innate immune responses including the expression of chemokines and adhesion molecules that promote the recruitment of inflammatory cells necessary for elimination of the infecting bacteria. Infiltrated neutrophils are activated by corneal stromal collagen and release mediators that stimulate the production of pro–matrix metalloproteinases by corneal fibroblasts. Elastase produced by Pseudomonas aeruginosa (P. aeruginosa) activates these released metalloproteinases, resulting in the degradation of stromal collagen. The modulation of corneal fibroblast activation and of the interaction of these cells with inflammatory cells and bacteria is thus important to minimize corneal scarring during treatment of infectious keratitis. Pharmacological agents that are able to restrain such activities of corneal fibroblasts without allowing bacterial growth represent a potential novel treatment option for prevention of excessive scarring and tissue destruction in the cornea.

Japanese guidelines for allergic conjunctival diseases 2017

The definition, classification, pathogenesis, test methods, clinical findings, criteria for diagnosis, and therapies of allergic conjunctival disease are summarized based on the Guidelines for Clinical Management of Allergic Conjunctival Disease (Second Edition) revised in 2010. Allergic conjunctival disease is defined as "a conjunctival inflammatory disease associated with a Type I allergy accompanied by some subjective or objective symptoms." Allergic conjunctival disease is classified into allergic conjunctivitis, atopic keratoconjunctivitis, vernal keratoconjunctivitis, and giant papillary conjunctivitis. Representative subjective symptoms include ocular itching, hyperemia, and lacrimation, whereas objective symptoms include conjunctival hyperemia, swelling, folliculosis, and papillae. Patients with vernal keratoconjunctivitis, which is characterized by conjunctival proliferative changes called giant papilla accompanied by varying extents of corneal lesion, such as corneal erosion and shield ulcer, complain of foreign body sensation, ocular pain, and photophobia. In the diagnosis of allergic conjunctival diseases, it is required that type I allergic diathesis is present, along with subjective and objective symptoms accompanying allergic inflammation. The diagnosis is ensured by proving a type I allergic reaction in the conjunctiva. Given that the first-line drug for the treatment of allergic conjunctival disease is an antiallergic eye drop, a steroid eye drop will be selected in accordance with the severity. In the treatment of vernal keratoconjunctivitis, an immunosuppressive eye drop will be concomitantly used with the abovementioned drugs.

Formation of Segmental Rounded Nodules During Infiltration of Adult T-Cell Leukemia Cells Into the Ocular Mucous Membrane

PURPOSE

To document a case of adult T-cell leukemia (ATL) cell infiltration into the ocular mucous membrane that presented with rounded nodule formation.

METHODS

Observational case report.

RESULTS

A 36-year-old woman presented with bilateral conjunctival hyperemia and small papules on the legs and face. After complaining of significant fatigue at 6 months, she was diagnosed with high-risk chronic-type ATL. Ophthalmic examination revealed the formation of bilateral segmental rounded nodules, which were located both at the bulbar conjunctiva around the corneal limbus and at the palpebral conjunctiva around each lacrimal punctum. Although cellular infiltrations were also seen at the corneal subepithelium and stroma, no cellular infiltrations were observed in the anterior chamber, vitreous, or retina. Biopsy was performed of the bulbar and palpebral conjunctiva, and the polymerase chain reaction detected HTLV-1 proviral DNA and monoclonal T-cell receptor γ-chain gene rearrangement in both samples. Pathological evaluations identified atypical lymphoid cells that were consistent with ATL cells. These analyses confirmed that the rounded nodules were formed in conjunction with the infiltration of ATL cells.

CONCLUSIONS

The formation of multiple rounded nodules during ATL cell infiltration into the ocular mucous membrane, especially at the palpebral conjunctiva around the lacrimal punctum, may be a distinguishing feature of ATL.

IL-27 enhances innate immunity of human pulmonary fibroblasts and epithelial cells through upregulation of TLR4 expression

Lung tissue cells play an active role in the pathogenesis of pulmonary inflammatory diseases by releasing a variety of cytokines and chemokines. However, how lung tissue cells respond to microbial stimuli during pulmonary infections remains unclear. In this study, we found that patients with community-acquired pneumonia displayed increased IL-27 levels in bronchoalveolar lavage fluid and serum. We subsequently examined the immunopathological mechanisms for the activation of primary human lung fibroblasts and bronchial epithelial cells by IL-27. We demonstrated that IL-27 priming enhanced LPS-induced production of IL-6 and IL-8 from lung fibroblasts and bronchial epithelia cells via upregulating Toll-like receptor-4 (TLR4) expression. IL-27 upregulated TLR4 expression in lung fibroblasts through activation of Janus-activated kinase (JAK) and Jun NH2-terminal kinase (JNK) signaling pathways, and inhibition of the JAK pathway could partially decrease IL-27-induced TLR4 expression, while inhibition of JNK pathway could completely suppress IL-27-induced TLR4 expression. Our data suggest that IL-27 modulates innate immunity of lung tissue cells through upregulating TLR4 expression during pulmonary infections.

Targeting chemokine receptors in disease--a case study of CCR4

Since their early 1990s, the chemokine receptor family of G protein-coupled receptors (GPCRs) has been the source of much pharmacological endeavour. Best known for their key roles in recruiting leukocytes to sites of infection and inflammation, the receptors present themselves as plausible drug targets for therapeutic intervention. In this article, we will focus our attention upon CC Chemokine Receptor Four (CCR4) which has been implicated in diseases as diverse as allergic asthma and lymphoma. We will review the discovery of the receptors and their ligands, their perceived roles in disease and the successful targeting of CCR4 by both small molecule antagonists and monoclonal antibodies. We will also discuss future directions and strategies for drug discovery in this field.

Expression of thymus and activation-regulated chemokine (TARC) by human dermal cells, but not epidermal keratinocytes

BACKGROUND

Serum levels of thymus and activation-regulated chemokine (TARC/CCL17) have served as a reliable biomarker of disease progression of atopic dermatitis (AD). However, it remains to be scientifically explained why serum TARC levels correlate well with the degree of AD progression.

OBJECTIVE

We hypothesized that dermal cells, but not epidermal keratinocytes, are major cellular sources of TARC and thus responsible for subclinical skin inflammation. This study aimed to identify the skin cells that can produce TARC protein.

METHODS

Primary normal human epidermal keratinocytes (NHEK), dermal microvascular endothelial cells (HMVEC-dBl) and dermal fibroblasts (NHDF) were stimulated with TNF-α and IL-4, alone and in combination. TARC mRNA and protein levels were quantified by qPCR and ELISA, respectively. We also investigated the effects of such immunosuppressants as a corticosteroid (dexamethasone) and tacrolimus (FK506) on TARC production, and used various signaling inhibitors to evaluate the signaling pathways involved in TARC expression.

RESULTS

Although neither TNF-α nor IL-4 alone induced TARC production by any of the tested cell types, together they induced expression of TARC mRNA and appreciable amounts of TARC protein by HMVEC-dBl and NHDF, but not by NHEK. TARC production by those dermal cells was not inhibited by dexamethasone or FK506. TARC production by HMVEC-dBl was completely inhibited by NF-κB and p38 MAPK inhibitors, but not by an ERK inhibitor.

CONCLUSION

Dermal cells, but not epidermal keratinocytes, may be important cellular sources of TARC in AD skin. Therefore, even if epidermal eczematous lesions seem to be improved, complete inhibition of inflammation in the dermis is thought to be particularly important for suppressing both the TARC blood level and progression of AD. However, immunosuppressants did not directly inhibit TARC production by the dermal cells. Anti-inflammatory therapy may decrease TARC blood levels in AD patients indirectly, via its inhibitory effects on TNF-α- and/or IL-4-producing cells in the dermis.

Distinct conformations of the chemokine receptor CCR4 with implications for its targeting in allergy

CC chemokine receptor 4 (CCR4) is expressed by Th2 and regulatory T cells and directs their migration along gradients of the chemokines CCL17 and CCL22. Both chemokines and receptor are upregulated in allergic disease, making CCR4 a therapeutic target for the treatment of allergy. We set out to assess the mechanisms underlying a previous report that CCL22 is a dominant ligand of CCR4, which may have implications for its therapeutic targeting. Human T cells expressing endogenous CCR4 and transfectants engineered to express CCR4 were assessed for receptor function, using assays of calcium release, chemotaxis, receptor endocytosis, and ligand binding. Despite the two ligands having equal potency in calcium flux and chemotaxis assays, CCL22 showed dominance in both receptor endocytosis assays and heterologous competitive binding assays. Using two different CCR4-specific Abs, we showed that CCR4 exists in at least two distinct conformations, which are differentially activated by ligand. A major population is activated by both CCL17 and CCL22, whereas a minor population is activated only by CCL22. Mutation of a single C-terminal residue K310 within a putative CCR4 antagonist binding site ablated activation of CCR4 by CCL17, but not by CCL22, despite having no effect on the binding of either ligand. We conclude that CCL17 and CCL22 are conformationally selective ligands of CCR4 and interact with the receptor by substantially different mechanisms. This finding suggests that the selective blockade of CCR4 in allergy may be feasible when one CCR4 ligand dominates, allowing the inhibition of Th2 signaling via one ligand while sparing regulatory T cell recruitment via another.

CCL17/thymus and activation-regulated chemokine induces calcitonin gene-related peptide in human airway epithelial cells through CCR4

BACKGROUND

Calcitonin gene-related peptide (CGRP) is a potent arterial and venous vasodilator. Increased airway epithelial cell expression of CGRP, together with increased CCL17 expression, was previously observed in a model of provoked asthma in atopic human subjects.

OBJECTIVE

We sought to determine whether CCL17 induces CCR4-dependent CGRP synthesis and secretion by human airway epithelial cells.

METHODS

Human airway epithelial cell lines (BEAS-2B and A549) and human primary airway cells were cultured with CCL17 or various other cytokines, and CGRP expression was measured by using RT-PCR, quantitative immunofluorescence, and enzyme immunoassay. CCR4 expression was determined in cultured cells by using flow cytometry and in bronchial biopsy specimens by using immunohistochemistry.

RESULTS

CCL17 induced a several thousand-fold increase in CGRP mRNA expression and released peptide product from BEAS-2B and A549 cells in a time- and concentration-dependent fashion. Concentration-dependent CCL17-induced release of CGRP by primary human airway epithelial cells was also observed. Under comparable conditions, CCL17 induced greater CGRP release from BEAS-2B cells than either IL-13, a cytokine mixture (TNF-α, GM-CSF, and IL-1), or CCL22. CCR4 was expressed by BEAS-2B and A549 cells and internalized after ligation with CCL17. CCL17-induced CGRP release was inhibited by a specific anti-CCR4 blocking antibody. Bronchial biopsy specimens obtained from healthy volunteers and asthmatic patients before and after provoked asthma all exhibited CCR4 staining of equivalent intensity, indicating that the receptor is constitutively expressed.

CONCLUSIONS

CCL17-induced, CCR4-dependent release of CGRP by human airway epithelial cells represents a novel inflammatory pathway and a possible target in patients with asthma and allergic disease.

Synergy of IL-27 and TNF-α in regulating CXCL10 expression in lung fibroblasts

IL-27 is involved in inflammatory reactions. CXCL10 is an important chemokine contributing to airway inflammatory disease. In this study, we investigated whether IL-27 modulated the synthesis of CXCL10 in primary human lung fibroblasts (HLFs). HLFs were activated by IL-27 alone, or in combination with other cytokines. CXCL10 synthesis was measured by real-time PCR and ELISA. An examination of transcriptional regulation was performed via the transient transfection of promoter constructs, whereas mRNA stability was assessed by actinomycin D chase and real-time PCR. The underlying signaling pathways were studied by Western blotting and intracellular staining, using flow cytometry. Our results demonstrated that IL-27 induced and synergized with TNF-α to up-regulate CXCL10 mRNA and protein concentrations in a steroid-insensitive manner. This synergistic CXCL10 production was dependent on the transcriptional regulation of CXCL10 gene promoter activity and the enhanced stability of CXCL10 mRNA because of IL-27 and TNF-α, and this synergism was regulated by the activation of p38 mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-OH kinase (PI3K)-Akt dominantly, and in small part via NF-κB. Interestingly, IL-27 promoted the basal and enhanced TNF-α-induced phosphorylation of p38 MAPK and Akt, but not IκBα. Moreover, enhanced CXCL10 mRNA stability occurred via a p38 MAPK-dependent pathway. Finally, clinical analysis showed that IL-27 was detected in the bronchoalveolar lavage of patients with asthma, chronic obstructive pulmonary disease (COPD), and pulmonary tuberculosis (PTB), and increased IL-27 concentrations were correlated with increased CXCL10 concentrations in patients with COPD and PTB. Our findings suggest that IL-27 has the potential to amplify airway inflammation via the induction of CXCL10 from HLFs, in combination with TNF-α.

Comparative analysis of human-derived feeder layers with 3T3 fibroblasts for the ex vivo expansion of human limbal and oral epithelium

Corneal transplantation with cultivated limbal or oral epithelium is a feasible treatment option for limbal stem cell deficiency (LSCD). Currently utilized co-culture of stem cells with murine 3T3 feeder layer renders the epithelial constructs as xenografts. To overcome the potential risks involved with xenotransplantation, we investigated the use of human-derived feeder layers for the ex vivo expansion of epithelial (stem) cells. Human limbal and oral epithelium was co-cultured with mouse 3T3 fibroblasts, human dermal fibroblasts (DF), human mesenchymal stem cells (MSC), and with no feeder cells (NF). Cell morphology was monitored with phase-contrast microscopy, and stem cell characteristics were assessed by immunohistochemistry, real-time PCR for p63 and ABCG2, (stem cell markers), and by colony-forming efficiency (CFE) assay. Immunohistochemical analysis detected positive staining for CK3 (cornea specific marker) and Iβ1 and p63 (putative stem cell markers) in all culture conditions. The level of Iβ1 and p63 was significantly higher in both limbal and oral cells cultured on the 3T3 feeder, as compared to the MSC or NF group (p<0.01). This level was comparable to the cells cultured on DF. Expression of p63 and ABCG2 in limbal and oral epithelial cells in the 3T3 and DF groups was significantly higher than that in the MSC or NF group (p<0.01). No statistical difference was detected between 3T3 and DF groups. The CFE of both limbal and oral cells co-cultured on 3T3 fibroblasts was comparable to cells grown on DF, and was significantly higher than that of cells co-cultured with MSC or NF (p<0.01). Epithelial cells grown on a DF feeder layer maintained a stem cell-like phenotype, comparable to cells grown on a 3T3 feeder layer. In conclusion, DF provides a promising substitute for 3T3 feeder cells during cultivation of xenobiotic-free corneal equivalents.

Synergistic induction of eotaxin and VCAM-1 expression in human corneal fibroblasts by staphylococcal peptidoglycan and either IL-4 or IL-13

BACKGROUND

Common features of allergic or atopic ocular and skin diseases are the participation of Th2 lymphocytes and eosinophils and colonization by Staphylococcus aureus. To examine the role of interaction between Th2 cells and bacterial infection in tissue eosinophilia, we determined the effects of Th2 cytokines and peptidoglycan derived from the cell wall of S. aureus on corneal fibroblasts.

METHODS

Chemokine concentrations and the cell surface expression of adhesion molecules were determined by ELISAs, and chemokine and adhesion molecule mRNAs were quantitated by real-time PCR analysis. Signaling by the transcription factor NF-κB was evaluated by immunoblot and immunofluorescence analyses as well as by assay of DNA binding activity.

RESULTS

Among Th2 cytokines tested, only interleukin (IL)-4 and IL-13 induced a low level of eotaxin release by corneal fibroblasts, as did peptidoglycan. However, the combination of peptidoglycan and either IL-4 or IL-13 induced a marked synergistic increase both in eotaxin release (without affecting that of IL-8) and in the abundance of eotaxin mRNA. The combination of peptidoglycan and IL-4 or IL-13 also synergistically increased the surface expression of VCAM-1, but not that of ICAM-1. Peptidoglycan activated NF-κB in corneal fibroblasts, and inhibitors of NF-κB attenuated eotaxin release induced by peptidoglycan alone or in combination with IL-4 or IL-13.

CONCLUSIONS

Interaction of innate and adaptive immunity, as manifested by synergistic stimulation of eotaxin and VCAM-1 expression in corneal fibroblasts by peptidoglycan and Th2 cytokines, may play an important role in tissue eosinophilia associated with ocular allergy.

Early detection of tumor cells by innate immune cells leads to T(reg) recruitment through CCL22 production by tumor cells

In breast carcinomas, patient survival seems to be negatively affected by the recruitment of regulatory T cells (T(reg)) within lymphoid aggregates by CCL22. However, the mechanisms underpinning this process, which may be of broader significance in solid tumors, have yet to be described. In this study, we determined how CCL22 production is controlled in tumor cells. In human breast carcinoma cell lines, CCL22 was secreted at low basal levels that were strongly increased in response to inflammatory signals [TNF-α, IFN-γ, and interleukin (IL)-1β], contrasting with CCL17. Primary breast tumors and CD45(+) infiltrating immune cells appeared to cooperate in driving CCL22 secretion, as shown clearly in cocultures of breast tumor cell lines and peripheral blood mononuclear cells (PBMC) or their supernatants. We determined that monocyte-derived IL-1β and TNF-α are key players as monocyte depletion or neutralization of these cytokines attenuated secretion of CCL22. However, when purified monocytes were used, exogenous human IFN-γ was also required to generate this response suggesting a role for IFN-γ-producing cells within PBMCs. In this setting, we found that human IFN-γ could be replaced by the addition of (i) IL-2 or K562-activated natural killer (NK) cells or (ii) resting NK cells in the presence of anti-MHC class I antibody. Taken together, our results show a dialogue between NK and tumor cells leading to IFN-γ secretion, which in turn associates with monocyte-derived IL-1β and TNF-α to drive production of CCL22 by tumor cells and subsequent recruitment of T(reg). As one validation of this conclusion in primary breast tumors, we showed that NK cells and macrophages tend to colocalize within tumors. In summary, our findings suggest that at early times during tumorigenesis, the detection of tumor cells by innate effectors (monocytes and NK cells) imposes a selection for CCL22 secretion that recruits T(reg) to evade this early antitumor immune response.

The human cutaneous chemokine system

Irrespective of the immune status, the vast majority of all lymphocytes reside in peripheral tissues whereas those present in blood only amount to a small fraction of the total. It has been estimated that T cells in healthy human skin outnumber those present in blood by at least a factor of two. How lymphocytes within these two compartments relate to each other is not well understood. However, mounting evidence suggest that the study of T cell subsets present in peripheral blood does not reflect the function of their counterparts at peripheral sites. This is especially true under steady-state conditions whereby long-lived memory T cells in healthy tissues, notably those in epithelial tissues at body surfaces, are thought to fulfill a critical immune surveillance function by contributing to the first line of defense against a series of local threats, including microbes, tumors, and toxins, and by participating in wound healing. The relative scarcity of information regarding peripheral T cells and the factors regulating their localization is primarily due to inherent difficulties in obtaining healthy tissue for the extraction and study of immune cells on a routine basis. This is most certainly true for humans. Here, we review our current understanding of T cell homing to human skin and compare it when possible with gut-selective homing. We also discuss candidate chemokines that may account for the tissue selectivity in this process and present a model whereby CCR8, and its ligand CCL1, selectively regulate the homeostatic migration of memory lymphocytes to skin tissue.

Expression of interleukin-4 receptor α in human corneal epithelial cells

PURPOSE

We previously reported that human conjunctival epithelial cells expressed functioning interleukin-4 receptor α (IL-4Rα). In this study, we investigated whether human corneal epithelial cells also express functioning IL-4Rα.

METHODS

The presence of IL-4Rα mRNA and protein in human corneal epithelium was examined by reverse-transcriptase polymerase chain reaction (RT-PCR) and immunohistology, respectively. The cell surface expression of IL-4Rα and the transcripts upregulated upon IL-4Rα ligand (IL-4 or IL-13) stimulation were examined by flow cytometry and quantitative RT-PCR, respectively, using immortalized human corneal-limbal epithelial (HCLE) cells.

RESULTS

The mRNA and protein of IL-4Rα were detected in human corneal epithelium. Flow cytometry analysis showed the cell surface expression of IL-4Rα protein. Quantitative RT-PCR assay of HCLE cells showed the upregulation of the transcripts tumor necrosis factor alpha-induced protein 6 (TNFAIP6), RAS guanyl-releasing protein 1 (RASGRP1), carbonic anhydrase II (CA2), cytokine-inducible SH2-containing protein (CISH), hyaluronan synthase 3 (HAS3), calpain 14 (CAPN14), endothelin receptor type A (EDNRA), cathepsin C (CTSC), and lecithin retinol acyltransferase (LRAT) as well as human conjunctival epithelial cells.

CONCLUSION

Human corneal epithelial cells expressed functioning IL-4Rα, and stimulation of its ligands, IL-4 and IL-13, could induce the expression of various genes, e.g., antiinflammatory molecule genes such as TNFAIP6 and CISH and cellular differentiation and proliferation-related molecule genes such as RASGRP1, HAS3, EDNRA, and LRAT.

Japanese guideline for allergic conjunctival diseases

The definition, classification, pathogenesis, test methods, clinical findings, criteria for diagnosis, and therapies of allergic conjunctival disease are summarized based on the Guidelines for Clinical Management of Allergic Conjunctival Disease (Second Edition) revised in 2010. Allergic conjunctival disease is defined as "a conjunctival inflammatory disease associated with a Type I allergy accompanied by some subjective or objective symptoms." Allergic conjunctival disease is classified into allergic conjunctivitis, atopic keratoconjunctivitis, vernal keratoconjunctivitis, and giant papillary conjunctivitis. Representative subjective symptoms include ocular itching, hyperemia, and lacrimation, whereas objective symptoms include conjunctival hyperemia, swelling, folliculosis, and papillae. Patients with vernal keratoconjunctivitis, which is characterized by conjunctival proliferative changes called giant papilla accompanied by varying extents of corneal lesion, such as corneal erosion and shield ulcer, complain of foreign body sensation, ocular pain, and photophobia. In the diagnosis of allergic conjunctival diseases, it is required that type I allergic diathesis is present, along with subjective and objective symptoms accompanying allergic inflammation. The diagnosis is ensured by proving a type I allergic reaction in the conjunctiva. Given that the first-line drug for the treatment of allergic conjunctival disease is an antiallergic eye drop, a steroid eye drop will be selected in accordance with the severity. In the treatment of vernal keratoconjunctivitis, an immunosuppressive eye drop will be concomitantly used with the above mentioned drugs.

Cytokines and chemokines in immune-based ocular surface inflammation

Altered levels of several cytokines and chemokines have been found in different types of inflammatory ocular surface diseases, such as allergy or dry-eye syndrome. It has also been demonstrated that epithelial cells play a key role in the persistence and even initiation of chronic mucosal inflammation. The recent development of 'multiplex detection' technologies has facilitated the identification of specific patterns of expression of these molecules in some ocular immune-based inflammatory disorders. Analysis of these molecules in tissues, cells (in vivo and in vitro) and tears has revealed that not only inflammatory cells but also epithelial and fibroblast resident cells are sources of these molecules. The purpose of this review is to summarize recent studies in this field.

Poly(I:C) synergizes with Th2 cytokines to induce TARC/CCL17 in middle ear fibroblasts established from mucosa of otitis media with effusion

CONCLUSION

These results suggest that middle ear fibroblasts contribute to the recruitment of Th2 cells into the middle ear by producing thymus and activation-regulated chemokine (TARC).

OBJECTIVES

Intractable otitis media is more common in atopic subjects and asthmatics than in the otherwise normal population. Although type 2 T helper (Th2) cytokines play crucial roles in the middle ear of these populations, the mechanism underlying the predominance of Th2 cytokines has yet to be clarified. TARC has been known to facilitate recruitment of Th2 polarized cells, resulting in high levels of Th2 cytokines in the middle ear. We investigated whether middle ear-derived fibroblasts produce TARC when stimulated with poly(I:C) and Th2 cytokines (IL-4, IL-13).

MATERIALS AND METHODS

Fibroblast lines were established from middle ear mucosa. TARC mRNA expression was evaluated by real-time RT-PCR. The amount of TARC in the culture supernatants was measured by ELISA.

RESULTS

Poly(I:C) induced only TARC gene expression in middle ear-derived fibroblasts. Combined stimulation with poly(I:C) and Th2 cytokine (IL-4, IL-13) synergistically induced TARC production by the cultured middle ear-derived fibroblasts. This response was dose and time dependent.

Cutaneous lymphocyte antigen-positive T cells may predict the development of acute GVHD: alterations and differences of CLA+ T- and NK-cell fractions

Acute GVHD (aGVHD) is a serious complication after allogeneic SCT (allo-SCT). However, an adequate immunological index is not yet available for assessing its severity. We analyzed the fraction of cutaneous lymphocyte antigen (CLA)+ cells in peripheral blood T and natural killer (NK) cells in 33 patients and evaluated its association with aGVHD. The CLA+ T-cell fraction often increased 3-7 days before the onset of aGVHD, and the maximum percentage of CLA+ T cells in grades II-IV aGVHD cases was significantly higher than that in grade 0 or I aGVHD (P<0.01). When the cutoff value of the maximum CLA+ T-cell percentage was set at 20%, any higher percentage was a significant risk for the development of severe aGVHD (P<0.0001). The maximum CLA+ T-cell percentage was significantly correlated with a high body temperature, low percutaneous oxygen saturation, and fibrinogen/fibrin degradation product D-dimer level. The post-allo-SCT CLA+ T cells exhibited a high ability to produce IL-2 and IFN-gamma, and may be the effectors and immunological markers for aGVHD. The CLA+ NK-cell-fraction steadily increased 2-4 weeks after allo-SCT but was not influenced by aGVHD. The CLA+ T-cell percentage may predict the development of severe aGVHD in clinical settings.

CC chemokine ligand 17 in periodontal diseases: expression in diseased tissues and production by human gingival fibroblasts

BACKGROUND AND OBJECTIVE

It has been reported that T helper 2 (Th2) cells are related to exacerbation of periodontal disease. However, it is uncertain how the migration of Th2 cells is controlled. In this study, we examined the expression of CC chemokine ligand 17 (CCL17), which is a Th2 chemokine, in periodontal tissues. Moreover, we investigated the effects of cytokines and toll-like receptor (TLR) ligands on the production of CCL17 by human gingival fibroblasts (HGFs).

MATERIAL AND METHODS

We used immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR) to detect CCL17 in periodontal tissues. HGFs were exposed to cytokines and TLR ligands. Expression of CCL17 was examined by RT-PCR and enzyme-linked immunosorbent assay. We used signal transduction inhibitors in some experiments.

RESULTS

Both CCL17 and its receptor, CC chemokine receptor 4 (CCR4), were expressed in diseased periodontal tissues. A combination of tumour necrosis factor alpha (TNF-alpha) and interleukin (IL)-4/IL-13 increased CCL17 expression. Moreover, treatment of HGFs with a low dose of interferon-gamma (IFN-gamma) in combination with TNF-alpha and IL-4 or IL-13 had synergistic effects on the production of CCL17, whereas a high dose of IFN-gamma inhibited CCL17 production. Furthermore, Escherichia coli (E. coli) lipopolysaccharide (TLR4 ligand) and Pam3CSK4 (TLR2 ligand) inhibited CCL17 production by TNF-alpha + IL-4-stimulated HGFs, while CpG DNA (TLR9 ligand) enhanced TNF-alpha + IL-4 induced-CCL17 production by HGFs. Furthermore, a c-Jun NH2 terminal kinase (JNK) inhibitor, a phosphatidylinositol-3-kinase (PI3K) inhibitor and a nuclear factor kappa B (NF-kappa B) inhibitor inhibited CCL17 production by HGFs.

CONCLUSION

These results suggest that the CCL17 produced by HGFs may be involved in the migration of Th2 cells into inflamed tissues, and provide evidence that CCL17 production is controlled by cytokines and TLR ligands in periodontal disease.

Detrimental role of CC chemokine receptor 4 in murine polymicrobial sepsis

CC chemokine receptor 4 (CCR4) and its two ligands, CCL17 and CCL22, are critically involved in different immune processes. In models of lipopolysaccharide-induced shock, CCR4-deficient (CCR4(-/-)) mice showed improved survival rates associated with attenuated proinflammatory cytokine release. Using CCR4(-/-) mice with a C57BL/6 background, this study describes for the first time the role of CCR4 in a murine model of polymicrobial abdominal sepsis, the colon ascendens stent peritonitis (CASP). CASP-induced sepsis led to a massive downregulation of CCR4 in lymphoid and nonlymphoid tissues, whereas the expression of CCL17 and CCL22 was independent of the presence of CCR4. After CASP, CCR4(-/-) animals showed a strongly enhanced bacterial clearance in several organs but not in the peritoneal lavage fluid and the blood. In addition, significantly reduced levels of proinflammatory cytokines/chemokines were measured in organ supernatants as well as in the sera of CCR4(-/-) mice. CCR4 deficiency consequently resulted in an attenuated severity of systemic sepsis and a strongly improved survival rate after CASP or CASP with intervention. Thus, our data provide clear evidence that CCR4 plays a strictly detrimental role in the course of polymicrobial sepsis.

A survey for rhinitis in an automotive ring manufacturing plant

We report findings regarding otolaryngologist-confirmed rhinitis, current exposure to MWF aerosols, fungi, and endotoxins for workers in a plant manufacturing automobile piston rings. Questionnaire data showed that 61.5% of 187 workers exhibited rhinitis-related symptoms. Rhinitis was confirmed in 99 of 115 workers whom were medically examined. Otolaryngologist-confirmed rhinitis was present in 10 of 19 grinding workers (52.6%), 67 of 142 production workers (47.2%), and 22 of 26 quality control (QC) workers (84.6%). These rates are much higher than the rates of rhinitis-related symptoms in automobile plants and other occupational settings and quite high even allowing for the common occurrence of rhinitis in the general population. We found that rhinitis could develop even in workers exposed to less than 0.5mg/m(3) MWF aerosol. The average exposure to fungi exceeded 10 x 10(3) CFU/m(3), a level higher than that reported for other automobile plants. Although we were unable to identify significant risk factors for rhinitis using only the physician-confirmed rhinitis cases, this study concludes that exposure to MWF aerosol, which would include microbes and metals, could contribute to a high occurrence of rhinitis in grinding and production workers. Forty-nine workers (63.6%) of 77 rhinitis patients in grinding and production operations were determined to handle synthetic MWF directly. For QC workers, for whom the prevalence of physician-confirmed rhinitis was highest, exposure to a low level of MWF aerosol, including specific microbe species we couldn't identify, bright light, dry air, and certain work characteristics during inspection are possible risk factors for development of rhinitis. Further studies including identification of fungi species should be conducted so a firm conclusion can be made regarding the development of rhinitis in QC manufacturing plant workers.

Induction of TARC production by lipopolysaccharide and interleukin-4 in nasal fibroblasts

BACKGROUND

Th2 cell infiltration is a characteristic feature of allergic chronic sinusitis. However, the mechanisms that cause the predominance of Th2 cells in this disease have yet to be clarified. The airway is often exposed to not only Th2 cytokines but also bacterial products such as lipopolysaccharides (LPS). A CC chemokine, TARC, is a potent chemoattractant for Th2 cells. The objectives of this study were twofold. First, we examined whether nasal polyp fibroblasts were able to produce TARC when costimulated with LPS and IL-4. Second, we investigated whether there was any heterogeneity in TARC production among fibroblasts derived from different airway sites.

METHODS

Fibroblast lines were established from human biopsy tissue. The amount of TARC in the supernatants was measured by ELISA. The expression of TARC mRNA was quantitated by real-time PCR.

RESULTS

Combined stimulation with LPS and IL-4 significantly induced TARC production by nasal polyp fibroblasts in a dose- and time-dependent manner. This induction occurred in normal nasal fibroblasts, but not in normal lung fibroblasts.

CONCLUSIONS

Via TARC production, nasal fibroblasts may play an important role in the recruitment of Th2 cells into the sinus mucosa as well as nasal polyps. The heterogeneity in TARC production may reflect functional differences between upper and lower airway fibroblasts.

Serum levels of the Th1 promoter IL-12 and the Th2 chemokine TARC are elevated in erythema multiforme and Stevens-Johnson syndrome/toxic epidermal necrolysis and correlate with soluble Fas ligand expression. An immunoenzymatic study from the Italian Group of Immunopathology

BACKGROUND

No data exist as to Th2 chemokines in erythema multiforme (EM) and Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN).

OBJECTIVE

To evaluate thymus- and activation-regulated chemokine (TARC), macrophage-derived chemokine (MDC) and regulated upon activation, normal T-lymphocyte-expressed and secreted chemokine (RANTES) expression in EM and SJS/TEN and to correlate with the serum levels of the Th1 promoter interleukin (IL)-12 and soluble Fas ligand (sFasL).

MATERIALS AND METHODS

IL-12, sFasL, TARC, MDC and RANTES expression were analyzed by ELISA techniques in 31 untreated EM (n = 24) or SJS/TEN (n = 7) patients and in 28 healthy donors (HD).

RESULTS

EM and SJS/TEN exhibited significantly higher levels of TARC, IL-12 and sFasL with respect to HD. TARC upregulation paralleled both the IL-12 (p = 0.0225) and sFasL increase (p = 0.0194).

CONCLUSIONS

Our results support a role of TARC in the pathophysiology of EM/SJS/TEN and confirm the coexistence of a Th2 response in addition to the predominant Th1 profile.

Discovery of a novel human picornavirus in a stool sample from a pediatric patient presenting with fever of unknown origin

Fever of unknown origin (FUO) is a serious problem in the United States. An unidentified agent was cultured from the stool of an infant who presented with FUO. This virus showed growth in HFDK cells and suckling mice. Using DNase sequence-independent single-primer amplification, we identified several nucleotide sequences with a high homology to Theiler's murine encephalomyelitis virus. Nearly full-length viral genome sequencing and phylogenetic analysis demonstrate that this virus is a member of the Cardiovirus genus of the Picornaviridae family.

Polarized subsets of human T-helper cells induce distinct patterns of chemokine production by normal and systemic sclerosis dermal fibroblasts

The role of fibroblasts in inflammatory processes and their cross-talk with T cells is increasingly being recognized. Our aim was to explore the capacity of dermal fibroblasts to produce inflammatory chemokines potentially involved in fibrosis occurring in response to contact with polarized human T cells. Our findings indicate that the program of chemokine production by fibroblasts is differentially regulated depending on the T-helper (Th) cell subset used to activate them. Thus, Th1 and Th2 cells preferentially induced production of IFN-γ inducible protein (IP)-10 and IL-8, respectively, whereas monocyte chemoattractant protein (MCP)-1 was equally induced by both subsets at mRNA and protein levels. Neutralization experiments indicated that membrane-associated tumour necrosis factor-α and IL-1 played a major role in the induction of IL-8 and MCP-1 by Th1 and Th2 cells, whereas membrane-associated IFN-γ (present only in Th1 cells) was responsible, at least in part, for the lower IL-8 and higher IP-10 production induced by Th1 cells. The contributions of tumour necrosis factor-α, IL-1 and IFN-α were confirmed when fibroblasts were cultured separated in a semipermeable membrane from living T cells activated by CD3 cross-linking. We observed further differences when we explored signal transduction pathway usage in fibroblasts. Pharmacological inhibition of c-Jun N-terminal kinase and nuclear factor-κB resulted in inhibition of IL-8 mRNA transcription induced by Th1 cells but not that by Th2 cells, whereas inhibition of MEK/ERK (mitogen-activated protein kinase of extracellular signal-regulated kinase/extracellular signal-regulated kinase) and nuclear factor-κB resulted in inhibition of MCP-1 mRNA induced by Th2 but not by Th1 cells. Finally, no distinct differences in chemokine production were observed when the responses to T cell contact or to prototypic Th1 and Th2 cytokines were examined in systemic sclerosis versus normal fibroblasts. These findings indicate that fibroblasts have the potential to participate in shaping the inflammatory response through the activation of flexible programs of chemokine production that depend on the Th subset eliciting their response.

IL-4 induces expression of TARC/CCL17 via two STAT6 binding sites

A cardinal feature of allergic disorders and immune responses is enhanced leukocyte trafficking. This is largely orchestrated by chemokines. The CC chemokine thymus- and activation-regulated chemokine (TARC/CCL17) selectively attracts Th2 cells via the G protein-coupled chemokine receptor CCR4. We show here that TARC/CCL17 is expressed by human T cells upon stimulation with IL-4. Mapping of the transcriptional start site revealed the presence of two putative STAT6 binding motifs in proximity to the start position. EMSA and chromatin immunoprecipitation experiments demonstrated that STAT6 was able to bind to both motifs. A fragment of the TARC/CCL17 promoter containing both sites was tested in reporter gene assays for IL-4 inducibility. The promoter was inducible in a STAT6-deficient cell line only after introduction of functional STAT6. When mutations were inserted into one of the STAT6 motifs, IL-4-induced promoter activation was reduced. With both sites mutated, inducibility was completely abrogated. These data demonstrate collectively that T cells serve as a source of TARC/CCL17 when stimulated with IL-4 and that STAT6 is essential for this.

Fibroblasts as local immune modulators in ocular allergic disease

Vernal keratoconjunctivitis (VKC), a severe form of ocular allergic disease, is characterized by the formation of giant papillae at the upper tarsal conjunctiva and corneal lesions that threaten vision. Recent evidence indicates that resident fibroblasts function as immune modulators in the pathogenesis of the chronic allergic inflammation associated with VKC. The T helper 2 (Th2) cell-derived cytokines interleukin (IL)-4 and IL-13 stimulate the migration and proliferation of conjunctival fibroblasts as well as protecting these cells from apoptotic cell death, effects that likely underlie the hyperplasia of fibroblasts that contributes to the formation of giant papillae. Conjunctival fibroblasts also synthesize extracellular matrix proteins and tissue inhibitors of metalloproteinases as well as down-regulate the expression of matrix metalloproteinases in response to these cytokines, effects that likely contribute to the excessive deposition of extracellular matrix that is characteristic of giant papillae. Stimulation of fibroblasts in the corneal stroma with the combination of a proinflammatory cytokine and either IL-4 or IL-13 results in up-regulation of the expression of the chemokine eotaxin and thymus- and activation-regulated chemokine as well as of vascular cell adhesion molecule-1, which together mediate the infiltration and activation of eosinophils and Th2 cells. Fibroblasts therefore appear to play a central role in the induction and amplification of ocular allergic inflammation and the consequent development of giant papillae and corneal disorders in individuals with VKC. Fibroblasts and fibroblast-derived factors thus represent new and potentially important therapeutic targets for treatment of the giant papillae and corneal disorders associated with VKC.

Role of structural cells of the cornea and conjunctiva in the pathogenesis of vernal keratoconjunctivitis

Vernal keratoconjunctivitis (VKC) is a severe type of allergic conjunctival disease characterized by the presence both of various corneal epithelial and stromal lesions as well as of conjunctival proliferative changes such as giant papillae of the upper tarsal conjunctiva and limbal lesions. These clinical findings as well as various pathophysiological characteristics of VKC are distinct from those of other types of ocular allergy and allergic diseases of other organs. The outer eye possesses specific allergological characteristics, one of which is communication between the cornea and conjunctiva through a thin layer of tear fluid. Fibroblasts of the cornea and the conjunctiva are activated by proinflammatory and T helper 2 (Th2) cell-derived cytokines. Corneal fibroblasts enhance ocular allergic reactions as a result of their activation-induced expression both of chemokines such as eotaxin and TARC as well as of adhesion molecules such as ICAM-1 and VCAM-1, all of which together promote the activation and infiltration of eosinophils and Th2 lymphocytes. In contrast, corneal epithelial cells suppress such reactions by physically separating corneal fibroblasts from bioactive substances in tear fluid. Exaggerated proliferation of and deposition of extracellular matrix by conjunctival fibroblasts likely exacerbate conjunctival inflammation. Restoration of an intact corneal epithelium and inhibition of the activities of corneal and conjunctival fibroblasts may provide a basis for the development of new treatments for severe ocular allergic diseases such as VKC.

Immunosuppressive effects of CCL17 on pulmonary antifungal responses during pulmonary invasive aspergillosis

Aspergillus fumigatus-sensitized CCR4-deficient (CCR4-/-) mice exhibit an accelerated clearance of conidia during fungal asthma. In the present study, we examined the roles of CCL17 and CCL22, two CCR4 ligands, during pulmonary invasive aspergillosis in neutropenic mice. Kaplan-Meier survival curve analysis revealed that wild-type C57BL/6 (CCR4+/+) mice were significantly protected from the lethal effects of Aspergillus compared with their wild-type controls following systemic neutralization with anti-CCL17 but not anti-CCL22 antibodies. Systemic neutralization of CCL17 significantly increased whole-lung CCL2 levels. Mouse survival and histological analysis revealed that the receptor mediating the deleterious effects of CCL17 was CCR4 since mice genetically deficit in CCR4 (CCR4-/-) did not develop invasive aspergillosis. Enzyme-linked immunosorbent assay analysis of whole-lung samples at day 2 after conidial challenge in neutrophil-depleted CCR4-/- and CCR4+/+ mice revealed that whole-lung IL-12 levels were significantly increased in the CCR4-/- group compared with the wild-type group. Also at day 2 after conidial challenge, significantly greater numbers of CD11c+ F4/80+ and CD11c+/CD86+ but fewer CD3/NK1.1+ cells were present in the lungs of CCR4-/- mice compared with their wild-type counterparts. Thus, CCL17-CCR4 interactions dramatically impair the pulmonary antifungal response against A. fumigatus in neutropenic mice.

Aspergillus and asthma--any link?

The innate immune and acquired immune responses are not separate, parallel systems but form interdependent components of a single integrated immune response. This is nicely highlighted by an expanding database demonstrating that the innate immune response provides the acquired immune response with information about the origin of the antigen and the type of response required via pattern recognition receptors (PRRs). Aspergillus is among a growing list of allergens that can aggravate asthmatic responses. Significant pulmonary pathology is associated with Aspergillus-induced allergic and asthmatic lung disease characterized by increased Th2 cytokine generation, IgE and IgG, eosinophilia, airway hyper-responsiveness and airway remodeling. Experimental data from a model of chronic fungal asthma demonstrate that thymus associated and regulated chemokine (TARC/CCL17) and macrophage derived chemokine (MDC/CCL22), working via CCR4, directly impair the innate anti-fungal immune response, thereby promoting the maintenance of acquired Th2-mediated asthmatic disease. Both chemokines appear to accomplish this by regulating the expression of PRRs such as toll like receptors (TLRs) and triggering receptor expressed on myeloid cells (TREM-1) by immune cells. Thus, the link between Aspergillus and asthma appears to reside in the magnitude and appropriateness of the host innate immune response, and ongoing research is revealing promising targets for therapy.

Chemokines provide the sustained inflammatory bridge between innate and acquired immunity

In this review we focus on the role of chemokines in discreet areas of innate immunity and demonstrate that chemokines are key participants to not only the early inflammatory response to a foreign agent, but important to the sustained immune reaction. Our studies support the concept that a concerted and interactive innate and acquired immune reaction is key for an automatic, dynamic, sustained, and regulated response toward clearing foreign stimuli. It is imperative that the in vivo concept of innate and acquired immunity be considered a continuum of a global assault on a foreign agent and not as modes, which are independent of one another.

Occupational asthma

Substantial epidemiologic and clinical evidence indicates that agents inhaled at work can induce asthma. In industrialized countries, occupational factors have been implicated in 9 to 15% of all cases of adult asthma. Work-related asthma includes (1) immunologic occupational asthma (OA), characterized by a latency period before the onset of symptoms; (2) nonimmunologic OA, which occurs after single or multiple exposures to high concentrations of irritant materials; (3) work-aggravated asthma, which is preexisting or concurrent asthma exacerbated by workplace exposures; and (4) variant syndromes. Assessment of the work environment has improved, making it possible to measure concentrations of several high- and low-molecular-weight agents in the workplace. The identification of host factors, polymorphisms, and candidate genes associated with OA is in progress and may improve our understanding of mechanisms involved in OA. A reliable diagnosis of OA should be confirmed by objective testing early after its onset. Removal of the worker from exposure to the causal agent and treatment with inhaled glucocorticoids lead to a better outcome. Finally, strategies for preventing OA should be implemented and their cost-effectiveness examined.