Th17 cells demonstrate stable cytokine production in a proallergic environment

STAT3 Signaling Heterogeneity Underlies Cytokine-Expressing Fate in Th17 Cultures

The polarization of naive Th cells into differentiated subsets in vitro was a powerful approach to define the development and function of Th cells in vivo. Th cell cultures identified cytokines that promote polarization and defined the phenotype and stability of differentiated cells. One of the limitations of this approach is the heterogeneity of the differentiated culture, essentially with regard to what proportion of the culture is secreting the hallmark cytokine of interest. This heterogeneity has always been puzzling because all cells in the culture have been exposed to identical culture conditions. We examined this phenomenon using an Il17f lineage-tracing allele (Cost, Cre on seventeen transcript) crossed to stop-flox Rosa-YFP (yellow fluorescent protein) mice. We found that less than half of the cells in a Th17 culture become lineage-positive during a differentiation culture and that it is primarily cells that are lineage-positive that produce cytokines when cultures are restimulated after differentiation. We sorted and analyzed YFP-positive and YFP-negative cells and found similar expression of many Th17 transcription factors, although YFP-negative cells had increased expression of other lineage-defining transcription factors. We observed that YFP-negative cells had diminished expression of Stat3 and Il6ra, as well as decreased STAT3 activation. YFP-negative cells transduced with active STAT3 had significant increases in IL-17A expression, without increases in Th17 transcription factors. Taken together, these data suggest that there is a threshold of STAT3 activation that is required for efficient Th17 differentiation, and that even in a culture of homogeneous naive T cells there is heterogeneity in the receipt of early cytokine signals.

PD-L1 signaling in reactive astrocytes counteracts neuroinflammation and ameliorates neuronal damage after traumatic brain injury

BACKGROUND

Tissue damage and cellular destruction are the major events in traumatic brain injury (TBI), which trigger sterile neuroimmune and neuroinflammatory responses in the brain. While appropriate acute and transient neuroimmune and neuroinflammatory responses facilitate the repair and adaptation of injured brain tissues, prolonged and excessive neuroimmune and neuroinflammatory responses exacerbate brain damage. The mechanisms that control the intensity and duration of neuroimmune and neuroinflammatory responses in TBI largely remain elusive.

METHODS

We used the controlled cortical impact (CCI) model of TBI to study the role of immune checkpoints (ICPs), key regulators of immune homeostasis, in the regulation of neuroimmune and neuroinflammatory responses in the brain in vivo.

RESULTS

We found that de novo expression of PD-L1, a potent inhibitory ICP, was robustly and transiently induced in reactive astrocytes, but not in microglia, neurons, or oligodendrocyte progenitor cells (OPCs). These PD-L1⁺ reactive astrocytes were highly enriched to form a dense zone around the TBI lesion. Blockade of PD-L1 signaling enlarged brain tissue cavity size, increased infiltration of inflammatory Ly-6C^High monocytes/macrophages (M/Mɸ) but not tissue-repairing Ly-6C^LowF4/80⁺ M/Mɸ, and worsened TBI outcomes in mice. PD-L1 gene knockout enhanced production of CCL2 that is best known for its ability to interact with its cognate receptor CCR2 on Ly-6C^High M/Mϕ to chemotactically recruit these cells into inflammatory sites. Mechanically, PD-L1 signaling in astrocytes likely exhibits dual inhibitory activities for the prevention of excessive neuroimmune and neuroinflammatory responses to TBI through (1) the PD-1/PD-L1 axis to suppress the activity of brain-infiltrating PD-1⁺ immune cells, such as PD-1⁺ T cells, and (2) PD-L1 intrinsic signaling to regulate the timing and intensity of astrocyte reactions to TBI.

CONCLUSIONS

PD-L1⁺ astrocytes act as a gatekeeper to the brain to control TBI-related neuroimmune and neuroinflammatory responses, thereby opening a novel avenue to study the role of ICP-neuroimmune axes in the pathophysiology of TBI and other neurological disorders.

Age-related immune-modulating properties of seminal fluid that control the severity of asthma are gender specific

Reproductive organs play a pivotal role in asthma development and progression, especially in women. Endocrine environment changes associated with the menstrual cycle, pregnancy, and menopause can exacerbate the clinical features of asthma. Factors secreted by reproductive organs may be responsible for the gender difference and age-related changes in adult asthma. Here, we show that mammalian seminal fluid has anti-asthma effects exclusively in females. Exposure to murine seminal fluid markedly reduced eosinophilic airway inflammation in 2-month-old female mice upon ovalbumin inhalation. The anti-asthma effect with seminal fluid from 10-month-old males was double that with fluid from 2-month-old males, suggesting that it depended on male sexual maturation. We further found that seminal fluid from middle-aged human volunteers had beneficial effects in asthmatic female mice; these effects were associated with transcriptional repression of osteopontin and IL-17A, which are poor prognostic factors for asthma. In 2-month-old male mice, however, human seminal fluid failed to decrease asthmatic features and even enhanced osteopontin and IL-17A transcription. Our data demonstrate that age-related seminal fluid exerts opposing effects in asthmatic male and female mice. These findings may help the development of novel approaches to control the prevalence and age-related progression of asthma in women.

Interleukin-10 (IL-10) Produced by Mutant Toxic Shock Syndrome Toxin 1 Vaccine-Induced Memory T Cells Downregulates IL-17 Production and Abrogates the Protective Effect against Staphylococcus aureus Infection

Development of long-term memory is crucial for vaccine-induced adaptive immunity against infectious diseases such as Staphylococcus aureus infection. Toxic shock syndrome toxin 1 (TSST-1), one of the superantigens produced by S. aureus, is a possible vaccine candidate against infectious diseases caused by this pathogen. We previously reported that vaccination with less toxic mutant TSST-1 (mTSST-1) induced T helper 17 (Th17) cells and elicited interleukin-17A (IL-17A)-mediated protection against S. aureus infection 1 week after vaccination. In the present study, we investigated the host immune response induced by mTSST-1 vaccination in the memory phase, 12 weeks after the final vaccination. The protective effect and IL-17A production after vaccination with mTSST-1 were eliminated because of IL-10 production. In the presence of IL-10-neutralizing monoclonal antibody (mAb), IL-17A production was restored in culture supernatants of CD4⁺ T cells and macrophages sorted from the spleens of vaccinated mice. Vaccinated mice treated with anti-IL-10 mAb were protected against systemic S. aureus infection in the memory phase. From these results, it was suggested that IL-10 produced in the memory phase suppresses the IL-17A-dependent vaccine effect through downregulation of IL-17A production.

Effect of Lactobacillus acidophilus KLDS 1.0738 on miRNA expression in in vitro and in vivo models of β-lactoglobulin allergy

This study aims to investigate the correlation between the ability of L. acidophilus to modulate miRNA expression and prevent Th17-dominated β-lactoglobulin (β-Lg) allergy. In vitro immunomodulation was evaluated by measuring splenocyte proliferation, Th17-related immune response and miRNA expression in β-Lg-sensitized splenocytes cultured with live L. acidophilus. Next, the allergic mouse model was used to evaluate anti-allergy capability of lactobacilli. The β-Lg challenge led to induction of up-regulation of miR-146a, miR-155, miR-21 and miR-9 expression in both in vivo and in vitro, along with increased Th17-related cytokine levels and mRNA expression of RORγt and IL-17. However, treatment of live L. acidophilus significantly suppressed hypersensitivity responses and Th17 cell differentiation. Moreover, administration of live L. acidophilus reduced expression of four miRNAs, especially miR-146a and miR-155. In addition, the decreased expression of the miRNAs in the spleen of the L. acidophilus-treated group was closely associated with decrease of IL-17 and RORγt mRNA expression.

Transcriptional regulation of CD4+ TH cells that mediate tissue inflammation

Acquired and genetic immunodeficiencies have revealed an indispensable role for CD4⁺ T cells in the induction of protective host immune responses against a myriad of microbial pathogens. Influenced by the cytokines present in the microenvironment, activated CD4⁺ T cells may differentiate into several highly-specialized helper subsets defined by the production of distinct signature cytokines tailored to combat diverse classes of pathogens. The process of specification and differentiation is controlled by networks of core, master, and accessory transcription factors, which ensure that CD4⁺ T helper (T_H ) cell responses mounted against an invading microbe are of the correct specificity and type. However, aberrant activation or inactivation of transcription factors can result in sustained and elevated expression of immune-related genes, leading to chronic activation of CD4⁺ T_H  cells and organ-specific autoimmunity. In this review, we provide an overview of the molecular basis of CD4⁺ T_H  cell differentiation and examine how combinatorial expression of transcription factors, which promotes genetic plasticity of CD4⁺ T_H  cells, can contribute to immunological dysfunction of CD4⁺ T_H responses. We also discuss recent studies which highlight the potential of exploiting the genetic plasticity of CD4⁺ T_H  cells in the treatment of autoimmune and other immune-mediated disorders.

Role of IL-23 signaling in the progression of premalignant oral lesions to cancer

Mice bearing carcinogen-induced premalignant oral lesions were previously shown to have a pro-inflammatory phenotype, which is replaced with an immune inhibitory phenotype as lesions progress to cancer. Since Th17 cells are prominent at the premalignant lesion state and their levels are supported by IL-23, studies used mice that were IL-23 receptor deficient (IL-23R KO) to determine the requirement for IL-23 signaling in the immunological and clinical status of mice with premalignant oral lesions. The results showed a dependence on IL-23 signaling for the pro-inflammatory state of mice with oral lesions as levels of IL-2, IFN-γ, IL-6, IL-17 and TNF-α were elevated in wildtype mice with premalignant oral lesions, but not in IL-23R KO mice. In contrast, as lesions progressed to cancer, the pro-inflammatory phenotype subsided and was replaced with the inhibitory mediator IL-10 and with Treg cells in wildtype mice, although not in IL-23R KO mice. Clinically, early progression of premalignant oral lesions to cancer was enhanced in IL-23R KO mice compared to progression in wildtype mice. These results show the importance of IL-23 signaling in both the pro-inflammatory phenotype characteristic of premalignant oral lesions and the inhibitory phenotype as lesions progress to cancer.

A Mouse Model of Anaphylaxis and Atopic Dermatitis to Salt-Soluble Wheat Protein Extract

BACKGROUND

Wheat allergy and other immune-mediated disorders triggered by wheat proteins are growing at an alarming rate for reasons not well understood. A mouse model to study hypersensitivity responses to salt-soluble wheat protein (SSWP) extract is currently unavailable. Here we tested the hypothesis that SSWP extract from wheat will induce sensitization as well as allergic disease in mice.

METHODS

Female BALB/cJ mice were weaned onto a plant protein-free diet. The mice were injected a total of 4 times with an SSWP (0.01 mg/mouse) fraction extracted from durum wheat along with alum as an adjuvant. Blood was collected biweekly and SSWP-specific IgE (SIgE) and total IgE (TIgE) levels were measured using ELISA. Systemic anaphylaxis upon intraperitoneal injection with SSWP was quantified by hypothermia shock response (HSR). Mucosal mast cell degranulation was measured by the elevation of mMCP-1 in the blood. The mice were monitored for dermatitis. Skin tissues were used in histopathology and for measuring cytokine/chemokine/adhesion molecule levels using a protein microarray system.

RESULTS

Injection with SSWP resulted in time-dependent SIgE antibody responses associated with the elevation of TIgE concentration. Challenge with SSWP elicited severe HSR that correlated with a significant elevation of plasma mMCP-1 levels. Sensitized mice developed facial dermatitis associated with mast cell degranulation. Lesions expressed significant elevation of Th2/Th17/Th1 cytokines and chemokines and E-selectin adhesion molecule.

CONCLUSION

Here we report a mouse model of anaphylaxis and atopic dermatitis to SSWP extract that may be used for further basic and applied research on wheat allergy.

STAT3 Activation Impairs the Stability of Th9 Cells

Th9 cells regulate multiple immune responses, including immunity to pathogens and tumors, allergic inflammation, and autoimmunity. Despite ongoing research into Th9 development and function, little is known about the stability of the Th9 phenotype. In this study, we demonstrate that IL-9 production is progressively lost in Th9 cultures during several rounds of differentiation. The loss of IL-9 is not due to an outgrowth of cells that do not secrete IL-9, as purified IL-9 secretors demonstrate the same loss of IL-9 in subsequent rounds of differentiation. The loss of IL-9 production correlates with increases in phospho-STAT3 levels within the cell, as well as the production of IL-10. STAT3-deficient Th9 cells have increased IL-9 production that is maintained for longer in culture than IL-9 in control cultures. IL-10 is responsible for STAT3 activation during the first round of differentiation, and it contributes to instability in subsequent rounds of culture. Taken together, our results indicate that environmental cues dictate the instability of the Th9 phenotype, and they suggest approaches to enhance Th9 activity in beneficial immune responses.

The transcription factor network in Th9 cells

The development of T helper cell subsets requires activated T cells that respond to a polarizing cytokine environment resulting in the activation and expression of transcription factors. The subset-specific transcription factors bind and induce the production of specific effector cytokines. Th9 cells express IL-9 and develop in the presence of TGFβ, IL-4, and IL-2. Each of these cytokines activates signaling pathways that are required for Th9 differentiation and IL-9 production. In this review, I summarize what is currently understood about the signaling pathways and transcription factors that promote the Th9 genetic program, providing some perspective for the integration of the signals in regulating the Il9 gene and dictating the expression of other Th9-associated genes. I highlight how experiments in mouse cells have established a transcriptional network that is conserved in human T cells and set the stage toward defining the next important questions for a more detailed understanding of Th9 cell development and function.

Emerging roles of T helper 17 and regulatory T cells in lung cancer progression and metastasis

Lung cancer is a leading cause of cancer-related deaths worldwide. Lung cancer risk factors, including smoking and exposure to environmental carcinogens, have been linked to chronic inflammation. An integral feature of inflammation is the activation, expansion and infiltration of diverse immune cell types, including CD4⁺ T cells. Within this T cell subset are immunosuppressive regulatory T (Treg) cells and pro-inflammatory T helper 17 (Th17) cells that act in a fine balance to regulate appropriate adaptive immune responses.In the context of lung cancer, evidence suggests that Tregs promote metastasis and metastatic tumor foci development. Additionally, Th17 cells have been shown to be an integral component of the inflammatory milieu in the tumor microenvironment, and potentially involved in promoting distinct lung tumor phenotypes. Studies have shown that the composition of Tregs and Th17 cells are altered in the tumor microenvironment, and that these two CD4⁺ T cell subsets play active roles in promoting lung cancer progression and metastasis.We review current knowledge on the influence of Treg and Th17 cells on lung cancer tumorigenesis, progression, metastasis and prognosis. Furthermore, we discuss the potential biological and clinical implications of the balance among Treg/Th17 cells in the context of the lung tumor microenvironment and highlight the potential prognostic function and relationship to metastasis in lung cancer.

EFEITO DO EXTRATO AQUOSO DE PRÓPOLIS MARROM SOBRE A PRODUÇÃO DE IFN-γ APÓS IMUNIZAÇÃO CONTRA PARVOVÍRUS CANINO (CPV) E CORONAVÍRUS CANINO (CCoV)

O objetivo deste estudo foi avaliar a capacidade adjuvante imunoestimulatória do extrato aquoso de própolis marrom (EAPM) quando associado a uma vacina contra parvovírus canino (CPV) e coronavírus canino (CCoV), com relação à produção de IFN-γ. Camundongos foram vacinados com CPV e CCoV (3,0x106 TCDI50) em associação ou não com 400 μg/dose de EAPM. Trinta dias após a terceira dose foi realizado cultivo de esplenócitos para mensuração dos níveis de expressão de mRNA para IFN-γ nos animais imunizados. O aumento nos níveis de expressão de mRNA para IFN-γ para CCoV nos esplenócitos dos camundongos inoculados com a vacina contendo 400 μg/dose de EAPM foi evidenciado por RT-PCR, demonstrando a capacidade da própolis em estimular a resposta imune celular contra os antígenos desse vírus. Ao contrário, os níveis de IFN-γ para CPV não sofreram influência da presença do EAPM.

STAT4 is required for IL-23 responsiveness in Th17 memory cells and NKT cells

STAT4 is a critical mediator of inflammatory immunity and is required for all known IL-12 biological responses, including the induction of IFN-γ and development of Th1 cells. We demonstrate that IL-23, an IL-12-related cytokine, also requires STAT4 for optimal IL-17 secretion from memory T helper cells and NKT cells. Although IL-23 stimulation had modest effects on STAT4 activation, STAT4-deficiency results in reduced Il23r expression. These data demonstrate a restricted requirement for STAT4 in innate and adaptive IL-17-secreting T cell responses that might contribute to inflammatory immunity.