Differentiation of Th subsets inhibited by nonstructural proteins of respiratory syncytial virus is mediated by ubiquitination

Respiratory syncytial virus induces β2-adrenergic receptor dysfunction in human airway smooth muscle cells

Pharmacologic agonism of the β₂-adrenergic receptor (β₂AR) induces bronchodilation by activating the enzyme adenylyl cyclase to generate cyclic adenosine monophosphate (cAMP). β₂AR agonists are generally the most effective strategy to relieve acute airway obstruction in asthmatic patients, but they are much less effective when airway obstruction in young patients is triggered by infection with respiratory syncytial virus (RSV). Here, we investigated the effects of RSV infection on the abundance and function of β₂AR in primary human airway smooth muscle cells (HASMCs) derived from pediatric lung tissue. We showed that RSV infection of HASMCs resulted in proteolytic cleavage of β₂AR mediated by the proteasome. RSV infection also resulted in β₂AR ligand-independent activation of adenylyl cyclase, leading to reduced cAMP synthesis compared to that in uninfected control cells. Last, RSV infection caused stronger airway smooth muscle cell contraction in vitro due to increased cytosolic Ca²⁺ concentrations. Thus, our results suggest that RSV infection simultaneously induces loss of functional β₂ARs and activation of multiple pathways favoring airway obstruction in young patients, with the net effect of counteracting β₂AR agonist-induced bronchodilation. These findings not only provide a potential mechanism for the reported lack of clinical efficacy of β₂AR agonists for treating virus-induced wheezing but also open the path to developing more precise therapeutic strategies.

The role of Th17 cells in viral infections

The present review provides an overview of recent advances regarding the function of Th17 cells and their produced cytokines in the progression of viral diseases. Viral infections alone do not lead to virus-induced malignancies, as both genetic and host safety factors are also involved in the occurrence of malignancies. Acquired immune responses, through the differentiation of Th17 cells, form the novel components of the Th17 cell pathway when reacting with viral infections all the way from the beginning to its final stages. As a result, instead of inducing the right immune responses, these events lead to the suppression of the immune system. In fact, the responses from Th17 cells during persistent viral infections causes chronic inflammation through the production of IL-17 and other cytokines which provide a favorable environment for tumor growth and its development. Additionally, during the past decade, these cells have been understood to be involved in tumor progression and metastasis. However, further research is required to understand Th17 cells' immune mechanisms in the vast variety of viral diseases. This review aims to determine the roles and effects of the immune system, especially Th17 cells, in the progression of viral diseases; which can be highly beneficial for the diagnosis and treatment of these infections.

Regulatory T cells and T helper 17 cells in viral infection

CD4⁺ T cells are the central element of the adaptive immune responses and protect the body from a variety of pathogens. Starting from naive cells, CD4⁺ T cells can differentiate into various effector cell subsets with specialized functions including T helper (Th) 1, Th2, Th17, regulatory T (Treg) and T follicular helper (Tfh) cells. Among them, Tregs and Th17 cells show a strong plasticity allowing the functional adaptation to various physiological and pathological environments during immune responses. Although they are derived from the same precursor cells and their differentiation pathways are interrelated, the terminally differentiated cells have totally opposite functions. Studies have shown that Tregs and Th17 cells have rather complex interplays in viral infection: Th17 cells may contribute to immune activation and disease progression while Tregs may inhibit this process and play a key role in the maintenance of immune homoeostasis, possibly at the cost of compromised viral control. In this review, we take respiratory syncytial virus (RSV), hepatitis B virus (HBV)/hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infections as examples to discuss these interplays and their impacts on disease progression in viral infection.

Inactivated P. aeruginosa restores immune imbalance of chronic idiopathic urticaria

The main pathology involved in chronic idiopathic urticaria (CIU) is immunological dysfunction which mainly adapts to the immune system of body. Pseudomonas aeruginosa-mannose-sensitive hemagglutinin (PA) is an inactivated Pseudomonas aeruginosa biological product which displays a broad immune regulatory effect. The current study was designed to explore the protective nature of PA as an immune regulator in CIU. The participants were randomly divided into CIU + PA, CIU, control + PA and control group. lg E, anti FcεRI, anti IgE antibody, IL-4, IL-17, TGF-β1 and interferon-γ in the sera were assayed by ELISA. Then CD4⁺ T cells and CD19⁺ B cells were isolated from peripheral blood of patients with CIU (n = 10) and healthy control (n = 10). CD4⁺ T cells and CD19⁺ B proliferation and apoptosis were analyzed through CCK-8 and flow cytometry respectively. T helper cells differentiations were assessed by real-time PCR. The results revealed that compared with the control group, the curative effect of CIU + PA group was more effective than that of the CIU control group. There was a hyper proliferation of CD19⁺ B cells in the CIU patients. Moreover, it was also discovered that presence of Th1 decreased while Th2 cells increased in CIU patients. PA significantly inhibited the proliferation of CD19⁺ B and Th2 cells but at the same time promoted the proliferation of Th1 compared to healthy control. The conclusion arrived at from this study is that the PA displayed a remarkable regulatory effect in CD4⁺ T cells and CD19⁺ B cells function by promoting Th1 but inhibited Th2 and the hyperfunction of B cells of CIU patients.

Transcriptome analyses provide the first insight into the molecular basis of cold tolerance in Larimichthys polyactis

Larimichthys polyactis is one of the most economically important marine fish species that have become newly cultured in China in recent years. The gene expression changes that L. polyactis experiences in cold toleranceis still unknown, limiting the expansion of its cultivation, fast growth, and high yield. To investigate the molecular mechanism behind L. polyactis's cold tolerance and to provide a resource for conducting genetic research on L. polyactis, transcriptome sequencing using RNA-seq was performed on individuals that survived cold stress at 4 °C (cold tolerant, CT), and individuals that barely survived 4 °C (cold sensitive, CS), which was considered as the control. A number of 387,607,550 clean reads were obtained from the transcriptomes, and comparative transcriptomic analysis identified 141 differently expressed genes (DEGs), of which 67 were up-regulated and 74 were down-regulated in CT compared to CS under cold stress. Furthermore, ten differently expressed genes were selected from the RNA-Seq analysis to be further validated by real-time PCR. Functional network analysis indicated that L. polyactis adapted to cold stress by employing a series of mechanisms to minimize damages caused by exposure to cold temperatures. The molecular mechanisms identified through RNA-Seq included Extracellular matrix (ECM) receptor interaction, glycerolipid metabolism, regulation of autophagy and focal adhesion pathway as playing vital roles in cold tolerance in L. polyactis. This study may help elucidate how L. polyactis tolerates cold, which is of value for breeding cold-tolerant L. polyactis stocks for cultivation.

Peripheral immune cell markers in children with recurrent respiratory infections in the absence of primary immunodeficiency

The immune system of a child has a degree of immaturity that is maintained until 6–7 years of age. Immaturity may be due to age-related functional disorders in the immune response. A healthy child can contract a series of infections which contribute to the maturation of the immune system during the pre-pubertal period. If repeated infections with prolonged or severe complications occur during childhood, the presence of an immunodeficiency should then be considered. Much more frequent than primary immunodeficiency are recurrent infections (frequently involving the upper respiratory tract), which are less severe and occur under the conditions of an immune system with no apparent major defects. A child can present with 4 to 8 episodes of respiratory infections within a year, during the first 5 years of its life. The average duration of infection is 8 days and up to 2 weeks; if the child presents with 3 episodes of acute infections over a period of 6 months, the respiratory infections are then considered recurrent. The aim of this study was to identify the immunological changes or deviations that cause this clinical syndrome in children. For this purpose, 30 children with recurrent respiratory infections and 10 healthy children were included. Immunoglobulin levels were examined and immunophenotyping was performed. We found that the serum immunoglobulin levels were in the normal range in 70% of the children. On the contrary, our data revealed changes in peripheral cell populations, the most important being the decrease in the T-cluster of differentiation (CD)8⁺ and total B cell percentages and the increase in the number of memory B cells. The data obtained herein indicated that the decrease in the number of total B cells was mainly due to the decrease in the number of naive IgD⁺ B cells. On the whole, the findings of this study indicate that recurrent respiratory infections may be associated with an altered cellular immune response. In such situations, the investigation of immunological parameters, such as T and B cell subtypes could complete the clinical diagnosis and guide the treatment strategy, thus increasing the quality of life of patients.

Mesenchymal Stem Cells Promoted Lung Wound Repair through Hox A9 during Endotoxemia-Induced Acute Lung Injury

Objectives. Acute lung injury (ALI) is a common clinical critical disease. Stem cells transplantation is recognized as an effective way to repair injured lung tissues. The present study was designed to evaluate the effects of mesenchymal stem cells (MSCs) on repair of lung and its mechanism. Methods. MSCs carrying GFP were administrated via trachea into wild-type SD rats 4 hours later after LPS administration. The lung histological pathology and the distribution of MSCs were determined by HE staining and fluorescence microscopy, respectively. Next, differentially expressed HOX genes were screened by using real-time PCR array and abnormal expression and function of Hox A9 were analyzed in the lung and the cells. Results. MSCs promoted survival rate of ALI animals. The expression levels of multiple HOX genes had obvious changes after MSCs administration and HOX A9 gene increased by 5.94-fold after MSCs administration into ALI animals. HOX A9 was distributed in endothelial cells and epithelial cells in animal models and overexpression of Hox A9 can promote proliferation and inhibit inflammatory adhesion of MSCs. Conclusion. HoxA9 overexpression induced by MSCs may be closely linked with lung repair after endotoxin shock.

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.

Human respiratory syncytial virus non-structural protein NS1 modifies miR-24 expression via transforming growth factor-β

Human respiratory syncytial virus (RSV) is a major health challenge in the young and elderly owing to the lack of a safe and effective vaccine and proven antiviral drugs. Understanding the mechanisms by which viral genes and proteins modulate the host response to infection is critical for identifying novel disease intervention strategies. In this study, the RSV non-structural protein NS1 was shown to suppress miR-24 expression during infection. Lack of NS1 was linked to increased expression of miR-24, whilst NS1 overexpression suppressed miR-24 expression. NS1 was found to induce Kruppel-like factor 6 (KLF6), a transcription factor that positively regulates the transforming growth factor (TGF)-b pathway to induce cell cycle arrest. Silencing of KLF6 led to increased miR-24 expression via downregulation of TGF-β. Treatment with exogenous TGF-β suppressed miR-24 expression and induced KLF6. Confocal microscopy showed co-localization of KLF6 and RSV NS1. These findings indicated that RSV NS1 interacts with KLF6 and modulates miR-24 expression and TGF-β, which facilitates RSV replication.

The role of Th17 and Treg responses in the pathogenesis of RSV infection

The respiratory syncytial virus (RSV) represents the leading cause of viral bronchiolitis and pneumonia in children worldwide and is associated with high morbidity, hospitalization rate, and significant mortality rates. The immune response elicited by RSV is one of the main factors contributing to the pathogenesis of the disease. Two subsets of the cellular immune response, the T helper 17 cell (Th17) and the regulatory T-cell (Treg), and more particularly the balance between these two subsets, might play a significant role in the pathogenesis of the RSV infection. The developmental pathways of Th17 and Treg cells are closely and reciprocally interconnected and plasticity has been demonstrated from Treg toward Th17. During an RSV infection, the functions of both subsets are opposed to one another regarding viral clearance and clinical severity. Th17 and Treg cells offer a promising new view on the pathogenesis of an RSV infection and deserve further exploration.

Viral manipulation of the host immune response

Viruses are obligate intracellular parasites that require a host for essential machinery to replicate and ultimately be transmitted to new susceptible hosts. At the same time, the immune system has evolved to protect the human body from invasion by viruses and other pathogens. To counter this, viruses have developed an arsenal of strategies to not only avoid immune detection but to actively manipulate host immune responses to create an environment more favorable for infection. Here, we describe recent advances uncovering novel mechanisms by which viruses skew host immune responses through modulation of cytokine and chemokine signaling networks, interference with antigen presentation and T cell responses, and preventing antibody production.