Respiratory syncytial virus induces functional thymic stromal lymphopoietin receptor in airway epithelial cells

EFFECT OF ANTI-TSLPR MONOCLONAL ANTIBODY ON VIABILITY, PROAPOPTOTIC GENES EXPRESSION, AND PRODUCTION OF PRO-INFLAMMATORY CYTOKINES IN MCF-7 AND A549 CELLS

BACKGROUND

Thymic stromal lymphopoietin (TSLP) and its receptor (TSLPR) are expressed in various cancer cells. However, their role in cancer development is not well defined.

AIM

To investigate the effects of anti-TSLPR antibody on the viability, proapoptotic genes expression, and production of pro-inflammatory cytokines in MCF-7 and A549 cancer cells.

MATERIALS AND METHODS

MCF-7 and A549 cells were exposed to anti-TSLPR monoclonal antibody for 24, 48, and 72 h. The effect on cell viability was examined by MTT assay. The expression levels of TP53, BAX, and CASP3 genes were evaluated by the quantitative reverse transcription polymerase chain reaction (qRT-PCR). Levels of interleukin (IL)-6, tumor necrosis factor-alpha (TNF-α), and transforming growth factor (TGF-β1) were measured by the enzyme-linked immunosorbent assay (ELISA).

RESULTS

The treatment of MCF-7 cells with anti- TSLPR antibody slightly stimulates cell proliferation after 48 h and 72 h following initial cytotoxicity in 24 h with a significant reduction in IL-6 and TNF-α production. A significant increase in the BAX expression in anti-TSLPR treated cells at a concentration of 2.5 μg/ml at 24-h point was evident. In anti-TSLPR-treated A549 cells, no decrease in cell count was observed, and slight dose-dependent stimulation of cell proliferation was evident in 48 h and 72 h of culture. A significant increase in TP53, BAX, and CASP3 expression upon treatment with 2.5 μg/ml of anti-TSLPR was evident in A549 cells.

CONCLUSION

The effects of anti-TSLPR on cell viability, proapoptotic gene expression, and production of pro-inflammatory cytokines (IL-6 and TNF-α) vary in MCF-7 and A549 cells.

The Role of TSLP in Atopic Dermatitis: From Pathogenetic Molecule to Therapeutical Target

Atopic dermatitis (AD) is a kind of chronic skin disease with inflammatory infiltration, characterized by skin barrier dysfunction, immune response dysregulation, and skin dysbiosis. Thymic stromal lymphopoietin (TSLP) acts as a regulator of immune response, positively associated with AD deterioration. Mainly secreted by keratinocytes, TSLP interacts with multiple immune cells (including dendritic cells, T cells, and mast cells), following induction of Th2-oriented immune response during the pathogenesis of AD. This article primarily focuses on the TSLP biological function, the relationship between TSLP and different cell populations, and the AD treatments targeting TSLP.

Innate Type 2 Responses to Respiratory Syncytial Virus Infection

Respiratory syncytial virus (RSV) is a common and contagious virus that results in acute respiratory tract infections in infants. In many cases, the symptoms of RSV remain mild, however, a subset of individuals develop severe RSV-associated bronchiolitis. As such, RSV is the chief cause of infant hospitalization within the United States. Typically, the immune response to RSV is a type 1 response that involves both the innate and adaptive immune systems. However, type 2 cytokines may also be produced as a result of infection of RSV and there is increasing evidence that children who develop severe RSV-associated bronchiolitis are at a greater risk of developing asthma later in life. This review summarizes the contribution of a newly described cell type, group 2 innate lymphoid cells (ILC2), and epithelial-derived alarmin proteins that activate ILC2, including IL-33, IL-25, thymic stromal lymphopoietin (TSLP), and high mobility group box 1 (HMGB1). ILC2 activation leads to the production of type 2 cytokines and the induction of a type 2 response during RSV infection. Intervening in this innate type 2 inflammatory pathway may have therapeutic implications for severe RSV-induced disease.

Comparative Analysis of Thymic and Blood Treg in Myasthenia Gravis: Thymic Epithelial Cells Contribute to Thymic Immunoregulatory Defects

The thymus is involved in autoimmune Myasthenia gravis (MG) associated with anti-acetylcholine (AChR) antibodies. In MG, thymic regulatory T cells (Treg) are not efficiently suppressive, and conventional T cells (Tconv) are resistant to suppression. To better understand the specific role of the thymus in MG, we compared the phenotype and function of peripheral and thymic Treg and Tconv from controls and MG patients. Suppression assays with thymic or peripheral CD4 + T cells showed that the functional impairment in MG was more pronounced in the thymus than in the periphery. Phenotypic analysis of Treg showed a significant reduction of resting and effector Treg in the thymus but not in the periphery of MG patients. CD31, a marker lost with excessive immunoreactivity, was significantly reduced in thymic but not blood resting Treg. These results suggest that an altered thymic environment may explain Treg differences between MG patients and controls. Since thymic epithelial cells (TECs) play a major role in the generation of Treg, we co-cultured healthy thymic CD4 + T cells with control or MG TECs and tested their suppressive function. Co-culture with MG TECs consistently hampers regulatory activity, as compared with control TECs, suggesting that MG TECs contribute to the immune regulation defects of MG CD4 + T cells. MG TECs produced significantly higher thymic stromal lymphopoietin (TSLP) than control TECs, and a neutralizing anti-TSLP antibody partially restored the suppressive capacity of Treg derived from co-cultures with MG TECs, suggesting that TSLP contributed to the defect of thymic Treg in MG patients. Finally, a co-culture of MG CD4 + T cells with control TECs restored numbers and function of MG Treg, demonstrating that a favorable environment could correct the immune regulation defects of T cells in MG. Altogether, our data suggest that the severe defect of thymic Treg is at least partially due to MG TECs that overproduce TSLP. The Treg defects could be corrected by replacing dysfunctional TECs by healthy TECs. These findings highlight the role of the tissue environment on the immune regulation.

Neonatal Immunity, Respiratory Virus Infections, and the Development of Asthma

Infants are exposed to a wide range of potential pathogens in the first months of life. Although maternal antibodies acquired transplacentally protect full-term neonates from many systemic pathogens, infections at mucosal surfaces still occur with great frequency, causing significant morbidity and mortality. At least part of this elevated risk is attributable to the neonatal immune system that tends to favor T regulatory and Th2 type responses when microbes are first encountered. Early-life infection with respiratory viruses is of particular interest because such exposures can disrupt normal lung development and increase the risk of chronic respiratory conditions, such as asthma. The immunologic mechanisms that underlie neonatal host-virus interactions that contribute to the subsequent development of asthma have not yet been fully defined. The goals of this review are (1) to outline the differences between the neonatal and adult immune systems and (2) to present murine and human data that support the hypothesis that early-life interactions between the immune system and respiratory viruses can create a lung environment conducive to the development of asthma.

A tumor-myeloid cell axis, mediated via the cytokines IL-1α and TSLP, promotes the progression of breast cancer

Tumors actively manipulate the immune response through the production of factors that attract immune cells and subsequently alter their ability to recognize and effectively remove the tumor. While this immune evasion mechanism is an important aspect of tumor survival, the factors that serve as primary growth factors for the tumor are less understood. Here, we demonstrated a novel mechanism by which breast cancer cells manipulate tumor-infiltrating myeloid cells to maintain their survival. Tumor-derived interleukin 1α (IL-1α), acting on infiltrating myeloid cells, induced the expression of a critical tumor survival factor, the cytokine thymic stromal lymphopoietin (TSLP). TSLP promoted the survival of the tumor cells through induction of Bcl-2 expression. TSLP signaling was also required for metastasis to the lung. These studies define a novel IL-1α–TSLP-mediated crosstalk between tumor-infiltrating myeloid cells and tumor cells in the control of metastatic breast cancer.

Thymic stromal lymphopoietin, IL-33, and periostin in hospitalized infants with viral bronchiolitis

Much attention has recently been focused on thymic stromal lymphopoietin (TSLP), IL-33, and periostin in allergic disease, but less is known about their role in viral bronchiolitis.The aim of the study was to investigate whether infants exhibit enhanced nasal airway secretion of TSLP, IL-33, and periostin during natural respiratory viral bronchiolitis compared to healthy controls.In total, 213 infants < 2 years of age, hospitalized with bronchiolitis from October/2013 to April/2016 were enrolled alongside 45 healthy infants. Nasopharyngeal aspirates (NPA) were screened for respiratory viruses by the polymerase chain reaction. TSLP, IL-33, and periostin were measured in NPAs. Clinical data were recorded.At least 1 virus was detected in 186 (87.3%) hospitalized infants: 149 (70%) respiratory syncytial virus (RSV); 42 (19.7%) rhinovirus (HRV); 16 (7.5%) parainfluenza virus (PIV); 9 (4.2%) adenovirus; 10 (4.7%) bocavirus; and 7 (3.3%) metapneumovirus (hMPV). Infants with bronchiolitis had higher levels of TSLP (P = .02), IL-33 (P<.001), and periostin (P = .003) than healthy controls.Detectable levels of TSLP and periostin were more frequent in virus-positive than in virus-negative patients (P = .05). TSLP and IL-33 were also more common in coinfections, mainly RSV and HRV, than in single-infections (P < .05). No patient with bronchiolitis but with negative viral detection had detectable levels of nasal TSLP or IL-33. Infants with hospital stay ≥5 days were more likely to have detectable levels of nasal TSLP and periostin after adjusting by age (P = .01).Bronchiolitis by common respiratory viruses is associated with elevated nasal levels of TSLP, IL-33, and periostin, factors known to be important in the development of Th2-response. Respiratory viruses in early life might shift immune responses toward Th2, involving asthma, and allergic diseases.

Human Respiratory Syncytial Virus: Infection and Pathology

The human respiratory syncytial virus (hRSV) is by far the major cause of acute lower respiratory tract infections (ALRTIs) worldwide in infants and children younger than 2 years. The overwhelming number of hospitalizations due to hRSV-induced ALRTI each year is due, at least in part, to the lack of licensed vaccines against this virus. Thus, hRSV infection is considered a major public health problem and economic burden in most countries. The lung pathology developed in hRSV-infected individuals is characterized by an exacerbated proinflammatory and unbalanced Th2-type immune response. In addition to the adverse effects in airway tissues, hRSV infection can also cause neurologic manifestations in the host, such as seizures and encephalopathy. Although the origins of these extrapulmonary symptoms remain unclear, studies with patients suffering from neurological alterations suggest an involvement of the inflammatory response against hRSV. Furthermore, hRSV has evolved numerous mechanisms to modulate and evade the immune response in the host. Several studies have focused on elucidating the interactions between hRSV virulence factors and the host immune system, to rationally design new vaccines and therapies against this virus. Here, we discuss about the infection, pathology, and immune response triggered by hRSV in the host.

Modulation of host adaptive immunity by hRSV proteins

Globally, the human respiratory syncytial virus (hRSV) is the major cause of lower respiratory tract infections (LRTIs) in infants and children younger than 2 years old. Furthermore, the number of hospitalizations due to LRTIs has shown a sustained increase every year due to the lack of effective vaccines against hRSV. Thus, this virus remains as a major public health and economic burden worldwide. The lung pathology developed in hRSV-infected humans is characterized by an exacerbated inflammatory and Th2 immune response. In order to rationally design new vaccines and therapies against this virus, several studies have focused in elucidating the interactions between hRSV virulence factors and the host immune system. Here, we discuss the main features of hRSV biology, the processes involved in virus recognition by the immune system and the most relevant mechanisms used by this pathogen to avoid the antiviral host response.

HPV16 E7 expression in skin induces TSLP secretion, type 2 ILC infiltration and atopic dermatitis-like lesions

Atopic dermatitis is a common pruritic and inflammatory skin disorder with unknown etiology. Most commonly occurring during early childhood, atopic dermatitis is associated with eczematous lesions and lichenification, in which the epidermis becomes hypertrophied resulting in thickening of the skin. In this study, we report an atopic dermatitis-like pathophysiology results in a murine model following the expression of the high-risk Human Papillomavirus (HPV) 16 oncoprotein E7 in keratinocytes under the Keratin 14 promoter. We show that HPV 16 E7 expression in the skin is associated with skin thickening, acanthosis and light spongiosis. Locally, HPV 16 E7 expressing skin secreted high levels of TSLP and contained increased numbers of ILCs. High levels of circulating IgE were associated with increased susceptibility to skin allergy in a model of cutaneous challenge, and to airway bronchiolar inflammation, enhanced airway goblet cell metaplasia and mucus production in a model of atopic march. Surprisingly, skin pathology occurred independently of T-cells and mast cells. Thus, our findings suggest that the expression of a single HPV oncogene in the skin can drive the onset of atopic dermatitis-like pathology through the induction of TSLP and type 2 ILC infiltration.

A molecular perspective on TH2-promoting cytokine receptors in patients with allergic disease

The cytokines IL-4, IL-13, and thymic stromal lymphopoietin play a key role in allergic disease by virtue of their ability to initiate, maintain, and augment TH2 responses. These molecules mediate their effects through type 1 cytokine receptors, which bind cytokines with a characteristic structure. Receptors are expressed on a broad array of immune cell types and are integral to complex cytokine networks operating in health and disease. TH2-promoting cytokines bind different configurations of receptors. Receptor subunits can exist in surface-bound or soluble forms, as well as in isolation or in partnership with other subunits. Sharing of receptor subunits among different cytokine receptor complexes adds to the intricate landscape. This article describes the characteristics of receptors for IL-4, IL-13, and thymic stromal lymphopoietin and their respective ligands from a structure-function perspective. We detail the mechanisms of receptor complex assembly, the interrelated nature of these receptors, and the effect on allergic inflammation. The ability for novel and atypical types of receptors to modulate inflammatory processes is also discussed. We highlight current and emerging treatments that target TH2-promoting receptor complexes. Understanding the molecular features of these receptors provides insight into different disease phenotypes and the variable clinical outcomes arising from targeted therapies. These considerations can be used to inform future directions for research and creative strategies for treating individual patients.