Th1 and type 1 cytotoxic T cells dominate responses in T-bet overexpression transgenic mice that develop contact dermatitis

T-bet Regulates Ion Channels and Transporters and Induces Apoptosis in Intestinal Epithelial Cells

T-bet, encoded by TBX21, is extensively expressed across various immune cell types, and orchestrates critical functions in their development, survival, and physiological activities. However, the role of T-bet in non-immune compartments, notably the epithelial cells, remains obscure. Herein, a Tet-O-T-bet transgenic mouse strain is generated for doxycycline-inducible T-bet expression in adult animals. Unexpectedly, ubiquitous T-bet overexpression causes acute diarrhea, intestinal damage, and rapid mortality. Cell-type-specific analyses reveal that T-bet-driven pathology is not attributable to its overexpression in CD4+ T cells or myeloid lineages. Instead, inducible T-bet overexpression in the intestinal epithelial cells is the critical determinant of the observed lethal phenotype. Mechanistically, T-bet overexpression modulates ion channel and transporter profiles in gut epithelial cells, triggering profound fluid secretion and subsequent lethal dehydration. Furthermore, ectopic T-bet expression enhances gut epithelial cell apoptosis and markedly suppresses colon cancer development in xenograft models. Collectively, the findings unveil a previously unrecognized role of T-bet in intestinal epithelial cells for inducing apoptosis, diarrhea, and local inflammation, thus implicating its potential as a therapeutic target for the treatment of cancer and inflammatory diseases.

Inhibition of DYRK1B suppresses inflammation in allergic contact dermatitis model and Th1/Th17 immune response

Allergic contact dermatitis (ACD) is a type IV hypersensitivity mainly mediated by Th1/Th17 immune response. Topical corticosteroid is currently the first-line treatment for allergic contact dermatitis (ACD) and systemic administration of immunosuppressive drugs are used in patients with severe disseminated cases. However, increased risk of adverse effects has limited their use. Thus, the development of a novel immunosuppressant for ACD with low toxicity is a challenging issue. In this study, we began our study by using a murine contact hypersensitivity (CHS) model of ACD to examine the immunosuppressive effects of DYRK1B inhibition. We found that mice treated with a selective DYRK1B inhibitor show reduced ear inflammation. In addition, a significant reduction of Th1 and Th17 cells in the regional lymph node upon DYRK1B inhibition was observed by FACS analysis. Studies in vitro further revealed that DYRK1B inhibitor does not only suppressed Th1 and Th17 differentiation, but also promotes regulatory T cells (Treg) differentiation. Mechanistically, FOXO1 signaling was enhanced due to the suppression of FOXO1^Ser329 phosphorylation in the presence of DYRK1B inhibitor. Therefore, these findings suggest that DYRK1B regulates CD4 T cell differentiation through FOXO1 phosphorylation and DYRK1B inhibitor has a potential as a novel agent for treatment of ACD.

Precision immunointerception of EGFR-driven tumorigenesis for lung cancer prevention

Epidermal growth factor receptor (EGFR) mutations occur in about 50% of lung adenocarcinomas in Asia and about 15% in the US. EGFR mutation-specific inhibitors have been developed and made significant contributions to controlling EGFR mutated non-small cell lung cancer. However, resistance frequently develops within 1 to 2 years due to acquired mutations. No effective approaches that target mutant EGFR have been developed to treat relapse following tyrosine kinase inhibitor (TKI) treatment. Vaccination against mutant EGFR is one area of active exploration. In this study, we identified immunogenic epitopes for the common EGFR mutations in humans and formulated a multi-peptide vaccine (E^mut Vax) targeting the EGFR L858R, T790M, and Del19 mutations. The efficacy of the E^mut Vax was evaluated in both syngeneic and genetic engineered EGFR mutation-driven murine lung tumor models with prophylactic settings, where the vaccinations were given before the onset of the tumor induction. The multi-peptide E^mut Vax effectively prevented the onset of EGFR mutation-driven lung tumorigenesis in both syngeneic and genetically engineered mouse models (GEMMs). Flow cytometry and single-cell RNA sequencing were conducted to investigate the impact of E^mut Vax on immune modulation. E^mut Vax significantly enhanced Th1 responses in the tumor microenvironment and decreased suppressive Tregs to enhance anti-tumor efficacy. Our results show that multi-peptide E^mut Vax is effective in preventing common EGFR mutation-driven lung tumorigenesis, and the vaccine elicits broad immune responses that are not limited to anti-tumor Th1 response.

Ablation of BATF Alleviates Transplant Rejection via Abrogating the Effector Differentiation and Memory Responses of CD8+ T Cells

Allogeneic CD8⁺ T cells are prominently involved in allograft rejection, but how their effector differentiation and function are regulated at a transcriptional level is not fully understood. Herein, we identified the basic leucine zipper ATF-like transcription factor (BATF) as a key transcription factor that drives the effector program of allogeneic CD8⁺ T cells. We found that BATF is highly expressed in graft-infiltrating CD8⁺ T cells, and its ablation in CD8⁺ T cells significantly prolonged skin allograft survival in a fully MHC-mismatched transplantation model. To investigate how BATF dictates allogeneic CD8⁺ T cell response, BATF^-/- and wild-type (WT) CD8⁺ T cells were mixed in a 1:1 ratio and adoptively transferred into B6.Rag1^-/- mice 1 day prior to skin transplantation. Compared with WT CD8⁺ T cells at the peak of rejection response, BATF^-/- CD8⁺ T cells displayed a dysfunctional phenotype, evident by their failure to differentiate into CD127^-KLRG1⁺ terminal effectors, impaired proliferative capacity and production of pro-inflammatory cytokines/cytotoxic molecules, and diminished capacity to infiltrate allografts. In association with the failure of effector differentiation, BATF^-/- CD8⁺ T cells largely retained TCF1 expression and expressed significantly low levels of T-bet, TOX, and Ki67. At the memory phase, BATF-deficient CD8⁺ T cells displayed impaired effector differentiation upon allogeneic antigen re-stimulation. Therefore, BATF is a critical transcriptional determinant that governs the terminal differentiation and memory responses of allogeneic CD8⁺ T cells in the transplantation setting. Targeting BATF in CD8⁺ T cells may be an attractive therapeutic approach to promote transplant acceptance.

Innate immunity and effector and regulatory mechanisms involved in allergic contact dermatitis

Skin's innate immunity is the initial activator of immune response mechanisms, influencing the development of adaptive immunity. Some contact allergens are detected by Toll-like receptors (TLRs) and inflammasome NLR3. Keratinocytes participate in innate immunity and, in addition to functioning as an anatomical barrier, secrete cytokines, such as TNF, IL-1β, and IL-18, contributing to the development of Allergic Contact Dermatitis. Dendritic cells recognize and process antigenic peptides into T cells. Neutrophils cause pro-inflammatory reactions, mast cells induce migration/maturation of skin DCs, the natural killer cells have natural cytotoxic capacity, the γδ T cells favor contact with hapten during the sensitization phase, and the innate lymphoid cells act in the early stages by secreting cytokines, as well as act in inflammation and tissue homeostasis. The antigen-specific inflammation is mediated by T cells, and each subtype of T cells (Th1/Tc1, Th2/Tc2, and Th17/Tc17) activates resident skin cells, thus contributing to inflammation. Skin's regulatory T cells have a strong ability to inhibit the proliferation of hapten-specific T cells, acting at the end of the Allergic Contact Dermatitis response and in the control of systemic immune responses. In this review, we report how cutaneous innate immunity is the first line of defense and focus its role in the activation of the adaptive immune response, with effector response induction and its regulation.

T-bet, but not Gata3, overexpression is detrimental in a neurotropic viral infection

Intracerebral Theiler's murine encephalomyelitis virus (TMEV) infection in mice induces inflammatory demyelination in the central nervous system. Although C57BL/6 mice normally resistant to TMEV infection with viral clearance, we have previously demonstrated that RORγt-transgenic (tg) C57BL/6 mice, which have Th17-biased responses due to RORγt overexpression in T cells, became susceptible to TMEV infection with viral persistence. Here, using T-bet-tg C57BL/6 mice and Gata3-tg C57BL/6 mice, we demonstrated that overexpression of T-bet, but not Gata3, in T cells was detrimental in TMEV infection. Unexpectedly, T-bet-tg mice died 2 to 3 weeks after infection due to failure of viral clearance. Here, TMEV infection induced splenic T cell depletion, which was associated with lower anti-viral antibody and T cell responses. In contrast, Gata3-tg mice remained resistant, while Gata3-tg mice had lower IFN-γ and higher IL-4 production with increased anti-viral IgG1 responses. Thus, our data identify how overexpression of T-bet and Gata3 in T cells alters anti-viral immunity and confers susceptibility to TMEV infection.

T-bet over-expression regulates aryl hydrocarbon receptor-mediated T helper type 17 differentiation through an interferon (IFN)γ-independent pathway

Various transcription factors are also known to enhance or suppress T helper type 17 (Th17) differentiation. We have shown previously that the development of collagen-induced arthritis was suppressed in T-bet transgenic (T-bet Tg) mice, and T-bet seemed to suppress Th17 differentiation through an interferon (IFN)-γ-independent pathway, although the precise mechanism remains to be clarified. The present study was designed to investigate further the mechanisms involved in the regulation of Th17 differentiation by T-bet over-expression, and we found the new relationship between T-bet and aryl hydrocarbon receptor (AHR). Both T-bet Tg mice and IFN-γ^-/- -over-expressing T-bet (T-bet Tg/IFN-γ^-/- ) mice showed inhibition of retinoic acid-related orphan receptor (ROR)γt expression and IL-17 production by CD4⁺ T cells cultured under conditions that promote Th-17 differentiation, and decreased IL-6 receptor (IL-6R) expression and signal transducer and activator of transcription-3 (STAT-3) phosphorylation in CD4⁺ T cells. The mRNA expression of ahr and rorc were suppressed in CD4⁺ T cells cultured under Th-17 conditions from T-bet Tg mice and T-bet Tg/IFN-γ^-/- mice. CD4⁺ T cells of wild-type (WT) and IFN-γ^-/- mice transduced with T-bet-expressing retrovirus also showed inhibition of IL-17 production, whereas T-bet transduction had no effect on IL-6R expression and STAT-3 phosphorylation. Interestingly, the mRNA expression of ahr and rorc were suppressed in CD4⁺ T cells with T-bet transduction cultured under Th17 conditions. The enhancement of interleukin (IL)-17 production from CD4⁺ T cells by the addition of AHR ligand with Th17 conditions was cancelled by T-bet over-expression. Our findings suggest that T-bet over-expression-induced suppression of Th17 differentiation is mediated through IFN-γ-independent AHR suppression.

Role of CD4+ T Cells in the Pathophysiology of Multiple Sclerosis

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system. Although the precise etiology of MS remains unclear, CD4⁺ T cells have been proposed to play not only effector but also regulatory roles in MS. CD4⁺ T cells can be divided into four subsets: pro-inflammatory helper T (Th) 1 and Th17 cells, anti-inflammatory Th2 cells and regulatory T cells (Tregs). The roles of CD4⁺ T cells in MS have been clarified by either “loss-of-function” or “gain-of-function” methods, which have been carried out mainly in autoimmune and viral models of MS: experimental autoimmune encephalomyelitis and Theiler's murine encephalomyelitis virus infection, respectively. Observations in MS patients were consistent with the mechanisms found in the MS models, that is, increased pro-inflammatory Th1 and Th17 activity is associated with disease exacerbation, while anti-inflammatory Th2 cells and Tregs appear to play a protective role.

Terminal NK cell maturation is controlled by concerted actions of T-bet and Zeb2 and is essential for melanoma rejection

The transcription factor Zeb2 cooperates with T-bet to control NK cell maturation, viability, and exit from the bone marrow and is essential for rejection of melanoma lung metastasis.

Natural killer (NK) cell maturation is a tightly controlled process that endows NK cells with functional competence and the capacity to recognize target cells. Here, we found that the transcription factor (TF) Zeb2 was the most highly induced TF during NK cell maturation. Zeb2 is known to control epithelial to mesenchymal transition, but its role in immune cells is mostly undefined. Targeted deletion of Zeb2 resulted in impaired NK cell maturation, survival, and exit from the bone marrow. NK cell function was preserved, but mice lacking Zeb2 in NK cells were more susceptible to B16 melanoma lung metastases. Reciprocally, ectopic expression of Zeb2 resulted in a higher frequency of mature NK cells in all organs. Moreover, the immature phenotype of Zeb2^−/− NK cells closely resembled that of Tbx21^−/− NK cells. This was caused by both a dependence of Zeb2 expression on T-bet and a probable cooperation of these factors in gene regulation. Transgenic expression of Zeb2 in Tbx21^−/− NK cells partially restored a normal maturation, establishing that timely induction of Zeb2 by T-bet is an essential event during NK cell differentiation. Finally, this novel transcriptional cascade could also operate in human as T-bet and Zeb2 are similarly regulated in mouse and human NK cells.

Th2-biased GATA-3 transgenic mice developed severe experimental peritoneal fibrosis compared with Th1-biased T-bet and Th17-biased RORγt transgenic mice

Encapsulating peritoneal sclerosis is one of the most serious complications of long-term peritoneal dialysis. The pathogenesis of encapsulating peritoneal sclerosis has not been elucidated, but several putative factors necessary for the development of peritoneum fibrosis (PF) have been reported. However, the roles of T helper (Th) cells in the progression of PF are unknown. The purpose of this study was to clarify the roles of Th1, Th2, and Th17 cells in the progression of PF. T-bet, GATA-3, and RORγt are Th1, Th2, and Th17 lineage commitment transcription factors, respectively. We previously generated Th1-biased (T-bet transgenic (Tg)) mice, Th2-biased (GATA-3 Tg) mice, and Th17-biased (RORγt Tg) mice. In this study, Th1, Th2, Th17-biased, and wild-type mice were administered chlorhexidine gluconate (CG) intraperitoneally and analyzed on day 21. CG-injected GATA-3 Tg mice showed a distended intestinal tract and developed marked thickening of the submesothelial space compared with the other groups. CG-injected GATA-3 Tg mice also showed significant expression of α-SMA positive cells, macrophages, and collagen III in the submesothelium. In contrast, CG-injected T-bet Tg mice only developed mild peritoneal fibrosis. Cytokines analysis in peritoneal fluid showed that IFN-γ was significantly increased in CG-injected T-bet Tg mice and that IL-13 was significantly increased in CG-injected GATA-3 Tg mice. Moreover, intraperitoneal administration of IFN-γ improved PF in GC-injected wild-type mice. Our results suggest that Th2 cells may play roles in the development of experimental PF and that Th1 cells may alleviate the severity of experimental PF.

Caribbean and La Réunion Chikungunya Virus Isolates Differ in Their Capacity To Induce Proinflammatory Th1 and NK Cell Responses and Acute Joint Pathology

Chikungunya virus (CHIKV) is a mosquito-borne arthralgic alphavirus that has garnered international attention as an important emerging pathogen since 2005. More recently, it invaded the Caribbean islands and the Western Hemisphere. Intriguingly, the current CHIKV outbreak in the Caribbean is caused by the Asian CHIKV genotype, which differs from the La Réunion LR2006 OPY1 isolate belonging to the Indian Ocean lineage. Here, we adopted a systematic and comparative approach against LR2006 OPY1 to characterize the pathogenicity of the Caribbean CNR20235 isolate and consequential host immune responses in mice. Ex vivo infection using primary mouse tail fibroblasts revealed a weaker replication efficiency by CNR20235 isolate. In the CHIKV mouse model, CNR20235 infection induced an enervated joint pathology characterized by moderate edema and swelling, independent of mononuclear cell infiltration. Based on systemic cytokine analysis, localized immunophenotyping, and gene expression profiles in the popliteal lymph node and inflamed joints, two pathogenic phases were defined for CHIKV infection: early acute (2 to 3 days postinfection [dpi]) and late acute (6 to 8 dpi). Reduced joint pathology during early acute phase of CNR20235 infection was associated with a weaker proinflammatory Th1 response and natural killer (NK) cell activity. The pathological role of NK cells was further demonstrated as depletion of NK cells reduced joint pathology in LR2006 OPY1. Taken together, this study provides evidence that the Caribbean CNR20235 isolate has an enfeebled replication and induces a less pathogenic response in the mammalian host.

IMPORTANCE The introduction of CHIKV in the Americas has heightened the risk of large-scale outbreaks due to the close proximity between the United States and the Caribbean. The immunopathogenicity of the circulating Caribbean CHIKV isolate was explored, where it was demonstrated to exhibit reduced infectivity resulting in a weakened joint pathology. Analysis of serum cytokine levels, localized immunophenotyping, and gene expression profiles in the organs revealed that a limited Th1 response and reduced NK cells activity could underlie the reduced pathology in the host. Interestingly, higher asymptomatic infections were observed in the Caribbean compared to the La Réunion outbreaks in 2005 and 2006. This is the first study that showed an association between key proinflammatory factors and pathology-mediating leukocytes with a less severe pathological outcome in Caribbean CHIKV infection. Given the limited information regarding the sequela of Caribbean CHIKV infection, our study is timely and will aid the understanding of this increasingly important disease.

Review of allergic contact dermatitis: Scratching the surface

Contact dermatitis-including allergic contact dermatitis (ACD)-n and results in over four million lost work days per year in the United States alone. ACD is a classic example of a type IV delayed hypersensitivity reaction, and represents a significant burden on the health system, economy, and patient quality of life. Thorough history taking, clinical examination, histologic evaluation, and patch testing are keys to diagnosing contact dermatitis. Patch testing, especially with comprehensive and customized panels based on the patient’s exposure history, is particularly useful in identifying potential allergens in the case of allergic contact dermatitis. ACD management requires a combination of direct medical intervention, patient education, and appropriate environmental modification to prevent exposure to offending allergens in the home or workplace. Continuing advances in the study of ACD has led to an increased understanding of the disease processes, new methods for diagnosis, and improved management. This article reviews ACD-aiming to connect recent investigational data with the current clinical understanding of disease pathophysiology, diagnostic techniques, and management strategies.

A lymphocyte-mediated cause of secondary PAP

In this issue of Blood, Iriguchi et al report that T-lymphocyte–restricted overexpression of T-bet causes a maturational arrest in mononuclear phagocyte lineage cells and severe secondary pulmonary alveolar proteinosis (PAP).

T-bet regulates differentiation of forkhead box protein 3+ regulatory T cells in programmed cell death-1-deficient mice

Programmed cell death-1 (PD-1) plays an important role in peripheral T cell tolerance, but whether or not it affects the differentiation of helper T cell subsets remains elusive. Here we describe the importance of PD-1 in the control of T helper type 1 (Th1) cell activation and development of forkhead box protein 3 (FoxP3(+)) regulatory T cells (Tr(egs)). PD-1-deficient T cell-specific T-bet transgenic (P/T) mice showed growth retardation, and the majority died within 10 weeks. P/T mice showed T-bet over-expression, increased interferon (IFN)-γ production by CD4(+) T cells and significantly low FoxP3(+) T(reg) cell percentage. P/T mice developed systemic inflammation, which was probably induced by augmented Th1 response and low FoxP3(+) T(reg) count. The study identified a unique, previously undescribed role for PD-1 in Th1 and T(reg) differentiation, with potential implication in the development of Th1 cell-targeted therapy.

RORγt, but not T-bet, overexpression exacerbates an autoimmune model for multiple sclerosis

Th17 cells play an important role in multiple sclerosis (MS) and its autoimmune model, experimental autoimmune encephalomyelitis (EAE). However, studies have not addressed how enhanced Th17 immune responses can affect demyelinating diseases. We induced EAE with MOG in RORγt transgenic C57BL/6 mice that overexpress a Th17 inducing transcription factor. RORγt transgenic mice developed more severe EAE than wild-type mice with more robust anti-MOG Th17 immune responses. In contrast, mice overexpressing T-bet, a Th1-inducing transcription factor, were resistant to EAE. Therefore, a genetic bias toward Th17 immune responses could contribute to CNS immunopathology.

T-cell-restricted T-bet overexpression induces aberrant hematopoiesis of myeloid cells and impairs function of macrophages in the lung

Although overexpression of T-bet, a master transcription factor in type-1 helper T lymphocytes, has been reported in several hematologic and immune diseases, its role in their pathogenesis is not fully understood. In the present study, we used transgenic model mice (T-bet(tg/wt) and T-bet(tg/tg)) to investigate the effects of T-bet overexpression selectively in T lymphocytes on the development of hematologic and immune diseases. The results showed that T-bet overexpression in T cells spontaneously induced maturation arrest in the mononuclear phagocyte lineage, as well as spontaneous dermatitis and pulmonary alveolar proteinosis (PAP)-like disease in T-bet(tg/wt) and T-bet(tg/tg) mice, respectively. T-bet(tg/tg) alveoli with the PAP phenotype showed remarkable reorganization of alveolar mononuclear phagocyte subpopulations and impaired function, in addition to augmented T-cell infiltration. In addition, PAP development in T-bet(tg/tg) mice was found to be associated with increased migration of myeloid cells from the bone marrow into the peripheral blood. These findings reveal an unexpected link between T-bet overexpression in T lymphocytes and the development of PAP caused by reorganization of mononuclear phagocytes in the lung, and provide new insight into the molecular pathogenesis of secondary PAP accompanied by hematologic disorders.

Innate lymphoid cells in the skin

Innate lymphoid cells (ILCs) are part of a heterogeneous family of innate immune cells with newly identified roles in mediating immunity, tissue homeostasis and pathologic inflammation. Here, we review recent studies delineating the roles of ILCs in the pathogenesis of multiple inflammatory skin disorders and their unique effector functions. Finally, we address how these studies have informed our understanding of the regulation of ILCs and the therapeutic potential of targeting these cells in the context of skin inflammation.

Overexpression of GATA-3 in T cells accelerates dextran sulfate sodium-induced colitis

Ulcerative colitis (UC) is an inflammatory bowel disease, and its pathogenesis includes genetic, environmental, and immunological factors, such as T helper cells and their secreted cytokines. T helper cells are classified as Th1, Th2, and Th17 cells. However, it is unclear which T helper cells are important in UC. Dextran sulfate sodium (DSS)-induced colitis is a commonly used model of UC. In this study, we induced DSS colitis in Th1 dominant (T-bet transgenic (Tg)) mice, Th2 dominant (GATA-3 Tg) mice, and Th17 dominant (RORγt Tg) mice to elucidate the roles of T helper cell in DSS colitis. The results showed that GATA-3 Tg mice developed the most severe DSS colitis compared with the other groups. GATA-3 Tg mice showed a significant decreased in weight from day 1 to day 7, and an increased high score for the disease activity index compared with the other groups. Furthermore, GATA-3 Tg mice developed many ulcers in the colon, and many neutrophils and macrophages were detected on day 4 after DSS treatment. Measurement of GATA-3-induced cytokines demonstrated that IL-13 was highly expressed in the colon from DSS-induced GATA-3 Tg mice. In conclusion, GATA-3 overexpression in T-cells and IL-13 might play important roles in the development of DSS colitis.

Inflammation programs self-reactive CD8+ T cells to acquire T-box-mediated effector function but does not prevent deletional tolerance

CD8(+) T cells must detect foreign antigens and differentiate into effector cells to eliminate infections. But, when self-antigen is recognized instead, mechanisms of peripheral tolerance prevent acquisition of effector function to avoid autoimmunity. These distinct responses are influenced by inflammatory and regulatory clues from the tissue environment, but the mechanism(s) by which naive T cells interpret these signals to generate the appropriate immune response are unclear. The identification of the molecules operative in these cell-fate decisions is crucial for developing new treatment options for patients with cancer or autoimmunity, where manipulation of T cell activity is desired to alter the course of disease. With the use of an in vivo murine model to examine CD8(+) T cell responses to healthy self-tissue, we correlated self-tolerance with a failure to induce the T-box transcription factors T-bet and Eomes. However, inflammation associated with acute microbial infection induced T-bet and Eomes expression and promoted effector differentiation of self-reactive T cells under conditions that normally favor tolerance. In the context of a Listeria infection, these functional responses relied on elevated T-bet expression, independent of Eomes. Alternatively, infection with LCMV induced higher Eomes expression, which was sufficient in the absence of T-bet to promote effector cytokine production. Our results place T-box transcription factors at a molecular crossroads between CD8(+) T cell anergy and effector function upon recognition of peripheral self-antigen, and suggest that inflammation during T cell priming directs these distinct cellular responses.

A nucleic acid-based medication for allergic skin diseases

Among allergic skin diseases, atopic dermatitis is the most difficult to cure. In the majority of patients, atopic dermatitis can be easily controlled by treatment based on three therapeutic approaches: avoidance of precipitating factors, skin care, and medication. In some adult patients, however, severe atopic dermatitis is refractory to treatment, and no fundamental effective treatment modality has yet been established for such cases. Chronic contact dermatitis without an identified causative hapten is also considered an allergic skin disease that is difficult to cure. Topical nucleic acid-based medications are currently being applied clinically, and an ointment containing nuclear factor-κB decoy oligodeoxynucleotides (hereafter referred to as Decoy) has reached clinical trials. In addition, synthetic double-stranded DNA with high affinity for signal transducers and activators of transcription 6 (STAT6) introduced in vivo as a decoy cis element to bind the transcriptional factor and block the activated gene that contributes to the onset and progression of atopic dermatitis functions as an effective therapeutic agent. We also introduce another STAT1 decoy treatment, cytosine-phosphate-guanine-ODN or STAT6 small interfering RNA therapy, for allergic skin diseases.

T-bet and Eomes instruct the development of two distinct natural killer cell lineages in the liver and in the bone marrow

Trail(+)DX5(-)Eomes(-) natural killer (NK) cells arise in the mouse fetal liver and persist in the adult liver. Their relationships with Trail(-)DX5(+) NK cells remain controversial. We generated a novel Eomes-GFP reporter murine model to address this question. We found that Eomes(-) NK cells are not precursors of classical Eomes(+) NK cells but rather constitute a distinct lineage of innate lymphoid cells. Eomes(-) NK cells are strictly dependent on both T-bet and IL-15, similarly to NKT cells. We observed that, in the liver, expression of T-bet in progenitors represses Eomes expression and the development of Eomes(+) NK cells. Reciprocally, the bone marrow (BM) microenvironment restricts T-bet expression in developing NK cells. Ectopic expression of T-bet forces the development of Eomes(-) NK cells, demonstrating that repression of T-bet is essential for the development of Eomes(+) NK cells. Gene profile analyses show that Eomes(-) NK cells share part of their transcriptional program with NKT cells, including genes involved in liver homing and NK cell receptors. Moreover, Eomes(-) NK cells produce a broad range of cytokines, including IL-2 and TNF in vitro and in vivo, during immune responses against vaccinia virus. Thus, mutually exclusive expression of T-bet and Eomes drives the development of different NK cell lineages with complementary functions.

Effects of intestinal bacteria-derived p-cresyl sulfate on Th1-type immune response in vivo and in vitro

Protein fermentation by intestinal bacteria generates various compounds that are not synthesized by their hosts. An example is p-cresol, which is produced from tyrosine. Patients with chronic kidney disease (CKD) accumulate high concentrations of intestinal bacteria-derived p-cresyl sulfate (pCS), which is the major metabolite of p-cresol, in their blood, and this accumulation contributes to certain CKD-associated disorders. Immune dysfunction is a CKD-associated disorder that frequently contributes to infectious diseases among CKD patients. Although some studies imply pCS as an etiological factor, the relation between pCS and immune systems is poorly understood. In the present study, we investigated the immunological effects of pCS derived from intestinal bacteria in mice. For this purpose, we fed mice a tyrosine-rich diet that causes the accumulation of pCS in their blood. The mice were shown to exhibit decreased Th1-driven 2, 4-dinitrofluorobenzene-induced contact hypersensitivity response. The concentration of pCS in blood was negatively correlated with the degree of the contact hypersensitivity response. In contrast, the T cell-dependent antibody response was not influenced by the accumulated pCS. We also examined the in vitro cytokine responses by T cells in the presence of pCS. The production of IFN-γ was suppressed by pCS. Further, pCS decreased the percentage of IFN-γ-producing Th1 cells. Our results suggest that intestinal bacteria-derived pCS suppressesTh1-type cellular immune responses.

Allergic contact dermatitis induces upregulation of identical microRNAs in humans and mice

BACKGROUND

MicroRNAs are short, endogenous RNA molecules that can bind to parts of target mRNAs, thus inhibiting their translation and causing accelerated turnover or degradation of transcripts, thereby regulating gene expression. Several microRNAs have been found to be upregulated in atopic dermatitis and psoriasis, indicating a role in inflammatory skin diseases. However, there have been no studies on the expression of microRNAs in allergic contact dermatitis.

OBJECTIVES

To investigate expression of microRNAs in allergic contact dermatitis. Methods. Lesional and non-lesional skin biopsies were collected from subjects with allergic responses to diphenylcyclopropenone (DPCP). Additional samples for profiling were collected from an experimental mouse model by use of the strong allergen dinitrofluorobenzene. RNA was purified from all samples, and locked nucleic acid microarray analysis was performed, followed by validation with quantitative polymerase chain reaction (PCR).

RESULTS

In humans sensitized with DPCP, we found significant upregulation of miR-21, miR-142-3p, miR-142-5p and miR-223 in challenged skin. The same microRNAs were significantly upregulated in the skin of mice in a mouse model of contact allergy. The upregulation of microRNA was confirmed by quantitative PCR.

CONCLUSION

These are the first results indicating that microRNAs may be involved in the pathogenesis of allergic contact dermatitis, and they show that mouse models are valuable tools for further study of the involvement of microRNAs in allergic contact dermatitis.

Contact sensitivity to metals (chromium, cobalt and nickel) in childhood

Metals, especially nickel, are the most common contact allergens in children. Recent data has shown increased incidence of allergy in industrialized countries. Sensitization can occur at any age, even in neonates. Costume jewelry, particularly earrings, is linked to increased sensitization to nickel. Sensitization to cobalt often occurs by the use of costume jewelry. The most common source of sensitization to chromium is leather. Due to the absence of a specific therapy, the main treatment is to identify and avoid the responsible allergens. This article presents an updated view on the epidemiological and clinical aspects of contact allergy to metals, focusing on prevention strategies and risk factors, and warns about possible and new sources of contact.

Transgenic modelling of cytokine polarization in the lung

The lung is one of the commonest sites of exposure to environmental allergen or pathogen, so the expression of a variety of cytokines in the lung is dynamically regulated by inflammatory or structural cells in the lung. In the last decades, characterization of the local lung cytokine milieu in allergic or injury models has identified a collective role of certain cytokines, such as type 1 or type 2 cytokines, driving polarized inflammatory and tissue phenotypes. With the development of transgenic mouse modelling systems, the effector function of individual cytokine and the pathophysiological consequences of cytokine polarization in the lung have been effectively evaluated. Here, we present an overview of the transgenic systems currently used to assess the biological function of cytokine or other mediators in the lung. We discuss the inflammatory and tissue phenotypes detected in the lungs of transgenic mice over-expressing representative T helper type 1 (interferon-γ, interleukin-12), T helper type 2 (interleukins -4, -5, -9, -10 and -13), and T helper type 17 cytokines. The effects of genetic modification of cytokine receptors or transcriptional factors such as GATA-3 and T-bet in pulmonary inflammation and remodelling tissue responses are also discussed because these transcription factors are regarded as essential regulators of cytokine polarization. Finally, we discuss the limitations and future application of transgenic approaches in the studies of human lung diseases characterized by cytokine polarization.

Cell adhesion molecules regulate fibrotic process via Th1/Th2/Th17 cell balance in a bleomycin-induced scleroderma model

Mice s.c. injected with bleomycin, an experimental model for human systemic sclerosis, develop skin and lung fibrosis, which is mediated by inflammatory cell infiltration. This process is highly regulated by multiple adhesion molecules and does not require Ag sensitization. To assess the role of adhesion molecules in this pathogenetic process, bleomycin-induced fibrosis was examined in mice lacking adhesion molecules. L-selectin and/or ICAM-1 deficiency inhibited skin and lung fibrosis with decreased Th2 and Th17 cytokines and increased Th1 cytokines. In contrast, P-selectin deficiency, E-selectin deficiency with or without P-selectin blockade, or P-selectin glycoprotein ligand 1 (PSGL-1) deficiency augmented the fibrosis in parallel with increased Th2 and Th17 cytokines and decreased Th1 cytokines. Furthermore, loss of L-selectin and/or ICAM-1 reduced Th2 and Th17 cell numbers in bronchoalveolar lavage fluid, whereas loss of P-selectin, E-selectin, or PSGL-1 reduced Th1 cell numbers. Moreover, Th1 cells exhibited higher PSGL-1 expression and lower expression of LFA-1, a ligand for ICAM-1, whereas Th2 and Th17 cells showed higher LFA-1 and lower PSGL-1 expression. This study suggests that L-selectin and ICAM-1 regulate Th2 and Th17 cell accumulation into the skin and lung, leading to the development of fibrosis, and that P-selectin, E-selectin, and PSGL-1 regulate Th1 cell infiltration, resulting in the inhibition of fibrosis.

Preventive and therapeutic potential of placental extract in contact hypersensitivity

Immunoregulatory effects of placental extract and placenta-derived factors have been demonstrated in various conditions. Accordingly, placental extract has been used as certain types of medical intervention in Asian countries, whereas experimental evidence supporting its therapeutic effects and mechanisms has yet to be fully demonstrated. In this study, we investigate preventive and therapeutic effects of placental extract in contact hypersensitivity (CHS), a mouse model of allergic contact dermatitis. Administration of placental extract prior to the sensitization of allergic antigen (Ag) significantly inhibited the severity of CHS induced by Ag challenge. This effect was associated with reduced numbers of CD4(+) T cells in peripheral blood, decrease of tissue-infiltrating lymphocytes, and preferential production of Th2-type cytokines in Ag-challenged sites. In addition, CHS caused by repetitive challenges of allergic Ag was also prevented and treated by administration of placental extract. Finally, administration of cyclo-trans-4-L-hydroxyprolyl-L-serine, a dipeptide derived from placental extract, also alleviated CHS, suggesting its potential role in the effects of placental extract in CHS. Taken together, our findings demonstrated experimental evidence supporting immunoregulatory effects of placental extract in allergic skin diseases and elucidated its potential mechanisms.

Induction of eosinophil- and Th2-attracting epidermal chemokines and cutaneous late-phase reaction in tape-stripped skin

Skin barrier damage induces various harmful or even protective reactions in the skin, as represented by enhancement of keratinocyte cytokine production. To investigate whether acute removal of stratum corneum modulates the production of chemokines by epidermal cells, we treated ears of BALB/c and C57BL/6 mice by tape-stripping, or acetone-rubbing as a control of acute barrier disruption procedure. There was no difference between the tape-stripped and acetone-rubbed skin sites in the increased and recovered levels of transepidermal water loss. The mRNA expression levels of all the chemokines tested, including Th1 chemokines (CXCL10, CXCL9 and CXCL11), Th2 chemokines (CCL17 and CCL22) and eosinophil chemoattractant (CCL5), were higher in the epidermal cells from BALB/c than in those of C57BL/6 mice. In particular, CCL17, CCL22 and CCL5 were remarkably elevated in BALB/c mice and augmented by tape-stripping more markedly than acetone-rubbing, whereas Th1 chemokines were enhanced by acetone-rubbing more remarkably. Tape-stripping induced dermal infiltration of eosinophils in BALB/c but not C57BL/6 mice. In a contact hypersensitivity model, where BALB/c mice were sensitized on the abdomen and challenged on the ears with fluorescein isothiocyanate, mice exhibited higher ear swelling responses at the late-phase as well as delayed-type reactions, when challenged via the tape-stripped skin. The challenge via tape-stripped skin augmented the expression of IL-4 and CCR4 in the skin homogenated samples, indicating infiltration of Th2 cells. These findings suggest that acute barrier removal induces the expression of Th2 and eosinophil chemokines by epidermal cells and easily evokes the late phase reaction upon challenge with antigen.

IL-17 and IFN-gamma mediate the elicitation of contact hypersensitivity responses by different mechanisms and both are required for optimal responses

Hapten-induced contact hypersensitivity (CHS) in the skin is a delayed type cellular immune response that can be mediated by CD8(+) T cells that produce IFN-gamma or IL-17. However, mechanisms for these cytokines in the elicitation of CHS remain to be fully elucidated. In this study, we show that adoptive transfer of CHS with hapten-primed wild-type (WT) CD8(+) T cells is reduced in IFN-gammaR(-/-) or IL-17R(-/-) mice compared with WT controls. The infiltration of granulocytes and macrophages in the hapten challenged skin of IL-17R(-/-) recipients is significantly reduced whereas it is less affected in IFN-gammaR(-/-) recipients although CD8(+) T cell infiltration is inhibited in both recipients. In contrast, the activity of reactive oxidative species is significantly inhibited in IFN-gammaR(-/-) but is less affected in IL-17R(-/-) recipients. Further analysis reveals that the expression of chemokines and cytokines is differentially regulated in the hapten-challenged skin of IFN-gammaR(-/-) or IL-17R(-/-) recipients compared with WT controls. Interestingly, injection of rIL-17 in the skin induces inflammation with a high level of leukocyte infiltration whereas injection of IFN-gamma induces inflammation with a high level of reactive oxidative species. Moreover, neutralization of IL-17 in IFN-gammaR(-/-) or IFN-gamma in IL-17R(-/-) mice further suppresses the adoptive transfer of CHS by hapten-primed WT CD8(+) T cells. The study demonstrates that IFN-gamma and IL-17 mediate the elicitation of CHS by different mechanisms and that both cytokines are required for optimal responses. This outcome improves understanding of pathogenesis and provides new insights into therapeutic strategies for CHS.

T-bet-deficient NOD mice are protected from diabetes due to defects in both T cell and innate immune system function

The transcription factor T-bet (Tbx21) is critical for Th1 polarization of CD4(+) T cells. Genetic deletion of Tbx21 can cause either exacerbation or attenuation of different autoimmune diseases in animal models. In the nonobese diabetic (NOD) mouse, genetic deletion of the Ifng or the Il12b (IL-12p40) genes, which are both critical Th1 cytokines, does not reduce the incidence of autoimmune diabetes. These results suggest that autoimmune diabetes in the NOD may not be a Th1-driven disease. However, we report that Tbx21 deficiency in the NOD mouse completely blocks insulitis and diabetes due to defects both in the initiation of the anti-islet immune response and in the function of CD4(+) effector T cells. We find defective priming of naive islet-reactive T cells by the innate immune system in Tbx21(-/-) animals. By contrast to naive cells, activated islet-reactive BDC2.5 TCR-transgenic T cells do not require Tbx21 in recipient animals for efficient adoptive transfer of diabetes. However, when these BDC2.5 TCR-transgenic effector cells lack Tbx21, they are less effective at entering the pancreas and promoting diabetes than Tbx21(+/+) cells. Tbx21(-/-) regulatory T cells function normally in vitro and diabetes can be restored in Tbx21(-/-) mice by reducing regulatory T cell numbers. Thus, the absence of diabetes in the NOD.Tbx21(-/-) is due to intrinsic defects in both T cells and cells of the innate immune system paired with the relative preservation of regulatory T cell function.

CD47 expression on T cell is a self-control negative regulator of type 1 immune response

The cytokine milieu and dendritic cells (DCs) direct Th1 development. Yet, the control of Th1 polarization by T cell surface molecules remains ill-defined. We here report that CD47 expression on T cells serves as a self-control mechanism to negatively regulate type 1 cellular and humoral immune responses in vivo. Th2-prone BALB/c mice that lack CD47 (CD47(-/-)) displayed a Th1-biased Ab profile at steady state and after immunization with soluble Ag. CD47(-/-) mice mounted a T cell-mediated exacerbated and sustained contact hypersensitivity (CHS) response. After their adoptive transfer to naive CD47-deficient hosts 1 day before immunization with soluble Ag, CD47(-/-) as compared with CD47(+/+)CD4(+) transgenic (Tg) T cells promoted the deviation of Ag-specific T cell responses toward Th1 that were characterized by a high IFN-gamma:IL-4 cytokine ratio. Although selective CD47 deficiency on DCs led to increased IL-12p70 production, CD47(-/-)Tg T cells produced more IFN-gamma and displayed higher T-bet expression than CD47(+/+) Tg T cells in response to OVA-loaded CD47(-/-) DCs. CD47 as part of the host environment has no major contribution to the Th1 polarization responses. We thus identify the CD47 molecule as a T cell-negative regulator of type 1 responses that may limit unwanted collateral damage to maximize protection and minimize host injury.

Th17 cells: a new therapeutic target in inflammatory dermatoses

Th17 cells, named for their secretion of interleukin-17 (IL-17), are a new class of T-cells involved in a wide range of cutaneous autoimmune and inflammatory conditions. An overactive Th17 cell response in the skin can produce damaging results. There appears to be a partial role for the Th17 axis in the pathogenesis of a range of dermatological diseases including allergic contact dermatitis, atopic dermatitis, psoriasis, and scleroderma. Immunologists have also discovered a unique association between Th17 cells and cutaneous T-cell lymphoma. The Th17 branch has been linked to a number of additional systemic inflammatory diseases with significant cutaneous pathology such as systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, and Behcet's disease. Newly developed treatment modalities for neutralizing the Th17 branch of the immune system are proving to be valuable additions to the current therapeutic armamentarium.

Differential cytokine and transcription factor expression in patients with allergic reactions to drugs

BACKGROUND

Allergic drug reactions (ADR) can be either immediate reaction (IR) (IgE mediated) or delayed reaction (DR) (T-cell mediated). They follow the Th1/Th2 paradigm, with DR expressing interferon-gamma (IFN-gamma) with down-regulation of interleukin-4 (IL-4) and IR expressing IL-4 with down-regulation of IFN-gamma. We studied the extension of this polarization in DR and IR by examining the cytokine and transcription factor profile in T-cell subpopulations during the acute phase of an ADR.

METHODS

Expressions of cytokines [IL-4, IFN-gamma and tumor necrosis factor-alpha (TNF-alpha)] and transcription factors (c-maf, GATA-3 and T-bet) were analysed by semi-quantitative real time-polymerase chain reaction in peripheral blood mononuclear cells and in CD4 and CD8 subpopulations from ADR patients.

RESULTS

In DR, IFN-gamma, TNF-alpha and T-bet increased significantly in both CD4 and CD8 subpopulations, depending on the clinical severity. In IR, IL-4, c-Maf and GATA-3 were increased, but only significantly in CD4. A positive correlation existed between IFN-gamma and T-bet in DR and between IL-4 and c-Maf and GATA-3 in IR. In DR, IFN-gamma, TNF-alpha and T-bet were increased during the acute phase in CD4 and CD8. In IR, IL-4, c-Maf and GATA-3 were all increased in the acute phase, but only in CD4.

CONCLUSIONS

These results support the Th1/Th2 paradigm in ADR, confirming previous findings that include the expression in both CD4 and CD8 T cells, and extending the observation to the transcription factors involved in the polarization of the immune response. Monitoring the reactions in the cell populations implicated, could be an important tool for assessing the mechanisms involved in ADR.

Signal transducer and activator of transcription 1 decoy oligodeoxynucleotide suppression of contact hypersensitivity

BACKGROUND

Cytokines play a pivotal role in allergy development through activating signaling mechanisms, such as the Janus kinase/signal transducer and activator of transcription (STAT) pathway, which controls the expression of numerous proinflammatory genes.

OBJECTIVE

In comparison with 2 different corticosteroids and a calcineurin inhibitor, the efficacy of a STAT1 decoy oligodeoxynucleotide (dODN)-containing ointment on hapten-induced contact hypersensitivity was examined in 3 different animal models.

METHODS

After sensitization, the test compounds were administered before hapten challenge, after hapten challenge, or both to different sites of the animal skin. Subsequent erythema and edema formation was scored macroscopically, microscopically, or by a shift in ear weight. Biopsy specimens were taken and processed for histopathology, immunohistochemistry, and real-time PCR analyses.

RESULTS

Treatment with the STAT1 dODN but not the corresponding control ODN markedly improved the clinical signs of inflammation in all 3 animal models in a dose-related manner. In guinea pig skin this was accompanied by a distinct decrease in leukocyte infiltration into the dermis after 24 hours. In addition, expression of CD40, IFN-gamma, IL-1beta, IL-8, IL-12, and TNF-alpha was strongly attenuated. The dODN was equally effective in the domestic pig model when administered therapeutically, and its preventive effect in the mouse model lasted for more than 48 hours.

CONCLUSIONS

Altogether, treatment with the dODN proved to be at least as effective as treatment with the reference compounds.