Human Rhinovirus Induced Cytokine/Chemokine Responses in Human Airway Epithelial and Immune Cells

Infections with human rhinovirus (HRV) are commonly associated with acute upper and lower respiratory tract disease and asthma exacerbations. The role that HRVs play in these diseases suggests it is important to understand host-specific or virus-specific factors that contribute to pathogenesis. Since species A HRVs are often associated with more serious HRV disease than species B HRVs, differences in immune responses they induce should inform disease pathogenesis. To identify species differences in induced responses, we evaluated 3 species A viruses, HRV 25, 31 and 36 and 3 species B viruses, HRV 4, 35 and 48 by exposing human PBMCs to HRV infected Calu-3 cells. To evaluate the potential effect of memory induced by previous HRV infection on study responses, we tested cord blood mononuclear cells that should be HRV naïve. There were HRV-associated increases (significant increase compared to mock-infected cells) for one or more HRVs for IP-10 and IL-15 that was unaffected by addition of PBMCs, for MIP-1α, MIP-1β, IFN-α, and HGF only with addition of PBMCs, and for ENA-78 only without addition of PBMCs. All three species B HRVs induced higher levels, compared to A HRVs, of MIP-1α and MIP-1β with PBMCs and ENA-78 without PBMCs. In contrast, addition of CBMCs had less effect and did not induce MIP-1α, MIP-1β, or IFN-α nor block ENA-78 production. Addition of CBMCs did, however, increase IP-10 levels for HRV 35 and HRV 36 infection. The presence of an effect with PBMCs and no effect with CBMCs for some responses suggest differences between the two types of cells possibly because of the presence of HRV memory responses in PBMCs and not CBMCs or limited response capacity for the immature CBMCs relative to PBMCs. Thus, our results indicate that different HRV strains can induce different patterns of cytokines and chemokines; some of these differences may be due to differences in memory responses induced by past HRV infections, and other differences related to virus factors that can inform disease pathogenesis.     

Trehalose-Mediated Autophagy Impairs the Anti-Viral Function of Human Primary Airway Epithelial Cells

Human rhinovirus (HRV) is the most common cause of acute exacerbations of chronic lung diseases including asthma. Impaired anti-viral IFN-λ1 production and increased HRV replication in human asthmatic airway epithelial cells may be one of the underlying mechanisms leading to asthma exacerbations. Increased autophagy has been shown in asthmatic airway epithelium, but the role of autophagy in anti-HRV response remains uncertain. Trehalose, a natural glucose disaccharide, has been recognized as an effective autophagy inducer in mammalian cells. In the current study, we used trehalose to induce autophagy in normal human primary airway epithelial cells in order to determine if autophagy directly regulates the anti-viral response against HRV. We found that trehalose-induced autophagy significantly impaired IFN-λ1 expression and increased HRV-16 load. Inhibition of autophagy via knockdown of autophagy-related gene 5 (ATG5) effectively rescued the impaired IFN-λ1 expression by trehalose and subsequently reduced HRV-16 load. Mechanistically, ATG5 protein interacted with retinoic acid-inducible gene I (RIG-I) and IFN-β promoter stimulator 1 (IPS-1), two critical molecules involved in the expression of anti-viral interferons. Our results suggest that induction of autophagy in human primary airway epithelial cells inhibits the anti-viral IFN-λ1 expression and facilitates HRV infection. Intervention of excessive autophagy in chronic lung diseases may provide a novel approach to attenuate viral infections and associated disease exacerbations.     

Th1 and Th17 Responses to Helicobacter pylori in Bangladeshi Infants,Children and Adults

Both Th1 and Th17 cells are important components of the immune response to Helicobacter pylori (Hp) in adults, but less is known about T cell responses to Hp during early childhood, when the infection is often acquired. We investigated Th1 and Th17 type responses to Hp in adults, children and infants in Bangladesh, where Hp is highly endemic. IL-17 and IFN-γ mRNA levels in gastric biopsies from Hp-infected Bangladeshi adults were analyzed and compared to levels in infected and uninfected Swedish controls. Since biopsies could not be collected from infants and children, cytokine responses in Bangladeshi infants (6–12 months), children (3–5 years) and adults (>19 years) were instead compared by stimulating peripheral blood mononuclear cells (PBMCs) with a Hp membrane preparation (MP) and analyzing culture supernatants by ELISA and cytometric bead array. We found significantly higher expression of IL-17 and IFN-γ mRNA in gastric mucosa of Hp-infected Bangladeshi and Swedish adults compared to uninfected Swedish controls. PBMCs from all age groups produced IL-17 and IFN-γ after MP stimulation, but little Th2 cytokines. IL-17 and IFN-γ were primarily produced by CD4⁺ T cells, since CD4⁺ T cell depleted PBMCs produced reduced amounts of these cytokines. Infant cells produced significantly more IL-17, but similar levels of IFN-γ, compared to adult cells after MP stimulation. In contrast, polyclonal stimulation induced lower levels IL-17 and IFN-γ in infant compared to adult PBMCs and CD4⁺ T cells. The strong IL-17 production in infants after MP stimulation was paralleled by significantly higher production of the IL-17 promoting cytokine IL-1β from infant compared to adult PBMCs and monocytes. In conclusion, these results show that T cells can produce high levels of IL-17 and IFN-γ in response to Hp from an early age and indicate a potential role for IL-1β in promoting Th17 responses to Hp during infancy.     

Increased Inflammatory Response in Cytomegalovirus Seropositive Patients with Alzheimer’s Disease

Alzheimer’s disease (AD) has been associated with increased local inflammation in the affected brain regions, and in some studies also with elevated levels of proinflammatory cytokines in peripheral blood. Cytomegalovirus (CMV) is known to promote a more effector-oriented phenotype in the T-cell compartment, increasing with age. The aim of this study was to investigate the inflammatory response of peripheral blood mononuclear cells (PBMCs) from AD patients and non-demented (ND) controls. Using a multiplex Luminex xMAP assay targeting GM-CSF, IFN-γ, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IP-10 and TNF-α, cytokine profiles from PBMCs were analysed after stimulation with anti-CD3/CD28 beads, CMV pp65 peptide mix or amyloid β (Aβ) protofibrils, respectively. CMV seropositive AD subjects presented with higher IFN-γ levels after anti-CD3/CD28 and CMV pp65 but not after Aβ stimulation, compared to CMV seropositive ND controls. When analysing IFN-γ response to anti-CD3/CD28 stimulation on a subgroup level, CMV seropositive AD subjects presented with higher levels compared to both CMV seronegative AD and CMV seropositive ND subjects. Taken together, our data from patients with clinically manifest AD suggest a possible role of CMV as an inflammatory promoter in AD immunology. Further studies of AD patients at earlier stages of disease, could provide better insight into the pathophysiology.     

The Placental Protein Syncytin-1 Impairs Antiviral Responses and Exaggerates Inflammatory Responses to Influenza

Background

Pregnancy increases susceptibility to influenza. The placenta releases an immunosuppressive endogenous retroviral protein syncytin-1. We hypothesised that exposure of peripheral monocytes (PBMCs) to syncytin-1 would impair responses to H1N1pdm09 influenza.

Methods and Findings

Recombinant syncytin-1 was produced. PBMCs from non-pregnant women (n=10) were exposed to H1N1pdm09 in the presence and absence of syncytin-1 and compared to responses of PBMCs from pregnant women (n=12). PBMCs were characterised using flow cytometry, release of interferon (IFN)-α, IFN-λ, IFN-γ, IL-10, IL-2, IL-6 and IL-1β were measured by cytometric bead array or ELISA. Exposure of PBMCs to H1N1pdm09 resulted in the release of IFN-α, (14,787 pg/mL, 95% CI 7311-22,264 pg/mL) IFN-λ (1486 pg/mL, 95% CI 756-2216 pg/mL) and IFN-γ (852 pg/mL, 95% CI 193-1511 pg/mL) after 48 hours. This was significantly impaired in pregnant women (IFN-α; p<0.0001 and IFN-λ; p<0.001). Furthermore, in the presence of syncytin-1, PBMCs demonstrated marked reductions in IFN-α and IFN-λ, while enhanced release of IL-10 as well as IL-6 and IL-1β.

Conclusions

Our data indicates that a placental derived protein, syncytin-1 may be responsible for the heightened vulnerability of pregnant women to influenza.     

Effects of Reticuloendotheliosis Virus Infection on Cytokine Production in SPF Chickens

Infection with reticuloendotheliosis virus (REV), a gammaretrovirus in the Retroviridae family, can result in immunosuppression and subsequent increased susceptibility to secondary infections. The effects of REV infection on expression of mRNA for cytokine genes in chickens have not been completely elucidated. In this study, using multiplex branched DNA (bDNA) technology, we identified molecular mediators that participated in the regulation of the immune response during REV infection in chickens. Cytokine and chemokine mRNA expression levels were evaluated in the peripheral blood mononuclear cells (PBMCs). Expression levels of interleukin (IL)-4, IL-10, IL-13 and tumor necrosis factor (TNF)-α were significantly up-regulated while interferon (IFN)-α, IFN-β, IFN-γ, IL-1β，IL-2, IL-3, IL-15, IL-17F, IL-18 and colony-stimulating factor (CSF)-1 were markedly decreased in PBMCs at all stages of infection. Compared with controls, REV infected chickens showed greater expression levels of IL-8 in PBMCs 21 and 28 days post infection. In addition, REV regulates host immunity as a suppressor of T cell proliferative responses. The results in this study will help us to understand the host immune response to virus pathogens.     

Respiratory Syncytial Virus Induced Type I IFN Production by pDC Is Regulated by RSV-Infected Airway Epithelial Cells,RSV-Exposed Monocytes and Virus Specific Antibodies

Innate immune responses elicited upon virus exposure are crucial for the effective eradication of viruses, the onset of adaptive immune responses and for establishing proper immune memory. Respiratory syncytial virus (RSV) is responsible for a high disease burden in neonates and immune compromised individuals, causing severe lower respiratory tract infections. During primary infections exuberant innate immune responses may contribute to disease severity. Furthermore, immune memory is often insufficient to protect during RSV re-exposure, which results in frequent symptomatic reinfections. Therefore, identifying the cell types and pattern recognition receptors (PRRs) involved in RSV-specific innate immune responses is necessary to understand incomplete immunity against RSV. We investigated the innate cellular response triggered upon infection of epithelial cells and peripheral blood mononuclear cells. We show that CD14⁺ myeloid cells and epithelial cells are the major source of IL-8 and inflammatory cytokines, IL-6 and TNF-α, when exposed to live RSV Three routes of RSV-induced IFN-α production can be distinguished that depend on the cross-talk of different cell types and the presence or absence of virus specific antibodies, whereby pDC are the ultimate source of IFN-α. RSV-specific antibodies facilitate direct TLR7 access into endosomal compartments, while in the absence of antibodies, infection of monocytes or epithelial cells is necessary to provide an early source of type I interferons, required to engage the IFN-α,β receptor (IFNAR)-mediated pathway of IFN-α production by pDC. However, at high pDC density infection with RSV causes IFN-α production without the need for a second party cell. Our study shows that cellular context and immune status are factors affecting innate immune responses to RSV. These issues should therefore be addressed during the process of vaccine development and other interventions for RSV disease.     

Differential Cytokine Profiles upon Comparing Selective versus Classic Glucocorticoid Receptor Modulation in Human Peripheral Blood Mononuclear Cells and Inferior Turbinate Tissue

Background

Glucocorticoid Receptor agonists, particularly classic glucocorticoids, are the mainstay among treatment protocols for various chronic inflammatory disorders, including nasal disease. To steer away from steroid-induced side effects, novel GR modulators exhibiting a more favorable therapeutic profile remain actively sought after. Currently, the impact of 2-(4-acetoxyphenyl)-2-chloro-N-methylethylammonium chloride a plant-derived selective glucocorticoid receptor modulator named compound A, on cytokine production in ex vivo human immune cells and tissue has scarcely been evaluated.

Methods and Results

The current study aimed to investigate the effect of a classic glucocorticoid versus compound A on cytokine and inflammatory mediator production after stimulation with Staphylococcus aureus–derived enterotoxin B protein in peripheral blood mononuclear cells (PBMCs) as well as in inferior nasal turbinate tissue. To this end, tissue fragments were stimulated with RPMI (negative control) or Staphylococcus aureus–derived enterotoxin B protein for 24 hours, in presence of solvent, or the glucocorticoid methylprednisolone or compound A at various concentrations. Supernatants were measured via multiplex for pro-inflammatory cytokines (IL-1β, TNFα) and T-cell- and subset-related cytokines (IFN-γ, IL-2, IL-5, IL-6, IL-10, and IL-17). In concordance with the previously described stimulatory role of superantigens in the development of nasal polyposis, a 24h Staphylococcus aureus–derived enterotoxin B protein stimulation induced a significant increase of IL-2, IL-1β, TNF-α, and IL-17 in PBMCs and in inferior turbinates and of IL-5 and IFN-γ in PBMCs.

Conclusion

Notwithstanding some differences in amplitude, the overall cytokine responses to methylprednisolone and compound A were relatively similar, pointing to a conserved and common mechanism in cytokine transrepression and anti-inflammatory actions of these GR modulators. Furthermore, these results provide evidence that selective glucocorticoid receptor modulator-mediated manipulation of the glucocorticoid receptor in human tissues, supports its anti-inflammatory potential.     

Regulation of Porcine Plasmacytoid Dendritic Cells by Cytokines

Plasmacytoid dendritic cells (pDC) are the most potent producers of type-I interferon (IFN) and represent the main interferon (IFN)-α source in response to many viruses. Considering the important roles played by type I IFN’s, not only as antiviral effectors but also as potent alarming cytokine of the immune system, we investigated how such responses are regulated by various cytokines. To this end, we stimulated enriched pDC in the presence or absence of particular cytokines with a strong activator, CpG DNA, or a weak activator of pDC, foot-and-mouth disease virus (FMDV). Alternatively, we pre-incubated pDC for 16 h before stimulation. The pro-inflammatory cytokines tested Interleukin (IL)-6, IL17A, tumour necrosis factor (TNF)-α did not influence IFN-α responses except TNF-α, which promoted responses induced by FMDV. The haematopoietic cytokines Fms-related tyrosine kinase 3 ligand (Flt3-L) and granulocyte-macrophage colony-stimulating factor (GM-CSF) had enhancing effects on pDC activation at least in one of the protocols tested. IFN-β and IFN-γ were the most potent at enhancing FMDV-induced IFN-α, up to 10-fold. Interestingly, also the Th2 cytokine IL-4 was an efficient promoter of pDC activity, while IL-10 was the only negative regulator of IFN-α in pDC identified. The cytokines enhancing IFN-α responses also promoted pDC survival in cell culture with the exception of GM-CSF. Taken together this work illustrates how the cytokine network can influence pDC activation, a knowledge of relevance for improving vaccines and therapeutic interventions during virus infections, cancers and autoimmune diseases in which pDC play a role.     

TGF-β and IL-10 Production by HIV-Specific CD8+ T Cells Is Regulated by CTLA-4 Signaling on CD4+ T Cells

Immune dysregulation in HIV-1 infection is associated with increased expression of inhibitory molecules such as CTLA-4, TGF-β, and IL-10. In this study we examined one potential mechanism for regulating TGF-β and IL-10 expression by HIV-specific suppressor CD8+ T cells. No overlap between TGF-β, IL-10, and IFN-γ cytokine production by HIV-specific CD8+ T cells was observed. TGF-β positive and IL-10 positive cells were FOXP3 negative, CD25 negative, and displayed a heterogeneous surface expression of CD127. TGF-β and IL-10 positive CD8+ T cells did not express CTLA-4. Nevertheless, CTLA-4 blockade resulted in a significant decrease in HIV-specific TGF-β positive and IL-10 positive CD8+ T cell responses, and a concomitant increase in HIV-specific IFN-γ positive CD8+ T cell responses. Depletion of CD4+ T cells abrogated the impact of CTLA-4 on HIV-specific TGF-β positive and IL-10 positive CD8+ T cells. Our study suggests that CTLA-4 Signaling on CD4+ T cells regulates the inhibitory functions of the HIV-specific suppressor CD8+ T cells.     

CD8+ T Cells Mediate Female-Dominant IL-4 Production and Airway Inflammation in Allergic Asthma

The prevalence and severity of bronchial asthma are higher in females than in males after puberty. Although antigen-specific CD8⁺ T cells play an important role in the development of asthma through their suppressive effect on cytokine production, the contribution of CD8⁺ T cells to sex differences in asthmatic responses remains unclear. In the present study, we investigated the sex-specific effect of CD8⁺ T cells in the suppression of asthma using an ovalbumin mouse model of asthma. The number of inflammatory cells in bronchoalveolar lavage (BAL) fluid, lung type 2 T-helper cytokine levels, and interleukin-4 (IL-4) production by bronchial lymph node cells were significantly higher in female wild-type (WT) mice compared with male mice, whereas no such sex differences were observed between male and female cd8α-disrupted mice. The adaptive transfer of male, but not female, CD8⁺ T cells reduced the number of inflammatory cells in the recovered BAL fluid of male recipient mice, while no such sex difference in the suppressive activity of CD8⁺ T cells was observed in female recipient mice. Male CD8⁺ T cells produced higher levels of IFN-γ than female CD8⁺ T cells did, and this trend was associated with reduced IL-4 production by male, but not female, CD4⁺ T cells. Interestingly, IFN-γ receptor expression on CD4⁺ T cells was significantly lower in female mice than in male mice. These results suggest that female-dominant asthmatic responses are orchestrated by the reduced production of IFN-γ by CD8⁺ T cells and the lower expression of IFN-γ receptor on CD4⁺ T cells in females compared with males.     

Effects of the Commercial Flame Retardant Mixture DE-71 on Cytokine Production by Human Immune Cells

IntroductionAlthough production of polybrominated diphenyl ethers (PBDEs) is now banned, release from existing products will continue for many years. The PBDEs are assumed to be neurotoxic and toxic to endocrine organs at low concentrations. Their effect on the immune system has not been investigated thoroughly. We aimed to investigate the influence of DE-71 on cytokine production by peripheral blood mononuclear cells (PBMCs) stimulated with Escherichia Coli lipopolysaccharide (LPS) or phytohaemagglutinin-L (PHA-L).ResultsAt non-cytotoxic concentrations (0.01–10 μg/mL), DE-71 significantly enhanced secretion of IL-1β, IL-6, CXCL8, IL-10, and TNF-α (p<0.001–0.019; n = 6) from LPS-stimulated PBMCs. IFN-γ, TNF-α, IL-17A, and IL-17F (p = <0.001–0.043; n = 6) secretion were enhanced from PHA-L-stimulated PBMCs as well. Secretion of IL-1β, IL-2, IL-10, IL-8 and IL-6 was not significantly affected by DE-71.ConclusionsWe demonstrate an enhancing effect of DE-71 on cytokine production by normal human PBMCs stimulated with LPS or PHA-L ex vivo.     

Budesonide and formoterol effects on rhinovirus replication and epithelial cell cytokine responses

Background

Combination therapy with budesonide and formoterol reduces exacerbations of asthma, which are closely associated with human rhinovirus (RV) infections in both children and adults. These data suggest that budesonide and formoterol inhibit virus-induced inflammatory responses of airway epithelial cells.

Methods

To test this hypothesis, bronchial epithelial (BE) cells were obtained from airway brushings of 8 subjects with moderate-to-severe allergic asthma and 9 with neither asthma nor respiratory allergies. Cultured BE cells were incubated for 24 hours with budesonide (1.77 μM), formoterol (0.1 μM), both, or neither, and then inoculated with RV-16 (5×10⁶ plaque forming units [PFU]/mL). After 24 hours, viral replication (RV RNA), cytokine secretion (CXCL8, CXCL10, TNFα, IFN-β, IL-28) and mRNA expression (CXCL8, CXCL10, TNF, IFNB1, IL28A&B) were analyzed.

Results

RV infection induced CXCL10 protein secretion and IFNB1 and IL28 mRNA expression. Drug treatments significantly inhibited secretion of CXCL10 in mock-infected, but not RV-infected, BE cells, and inhibited secretion of TNFα under both conditions. Neither budesonide nor formoterol, alone or in combination, significantly affected viral replication, nor did they inhibit RV-induced upregulation of IFNB1 and IL28 mRNA. Overall, RV replication was positively related to CXCL10 secretion and induction of IFNB1 and IL28 mRNA, but the positive relationship between RV RNA and CXCL10 secretion was stronger in normal subjects than in subjects with asthma.

Conclusions

Budesonide and formoterol can inhibit BE cell inflammatory responses in vitro without interfering with viral replication or production of interferons. These effects could potentially contribute to beneficial effects of budesonide/formoterol combination therapy in preventing RV-induced asthma exacerbations.     

TLR7/TLR8 Activation Restores Defective Cytokine Secretion by Myeloid Dendritic Cells but Not by Plasmacytoid Dendritic Cells in HIV-Infected Pregnant Women and Newborns

Mother-to-child transmission (MTCT) of HIV-1 has been significantly reduced with the use of antiretroviral therapies, resulting in an increased number of HIV-exposed uninfected infants. The consequences of HIV infection on the innate immune system of both mother-newborn are not well understood. In this study, we analyzed peripheral blood and umbilical cord blood (CB) collected from HIV-1-infected and uninfected pregnant women. We measured TNF-α, IL-10 and IFN-α secretion after the stimulation of the cells with agonists of both extracellular Toll-like receptors (TLRs) (TLR2, TLR4 and TLR5) and intracellular TLRs (TLR7, TLR7/8 and TLR9). Moreover, as an indicator of the innate immune response, we evaluated the responsiveness of myeloid dendritic cells (mDCs) and plasmacytoid DCs (pDCs) to TLRs that are associated with the antiviral response. Our results showed that peripheral blood mononuclear cells (PBMCs) from HIV-1-infected mothers and CB were defective in TNF-α production after activation by TLR2, TLR5, TLR3 and TLR7. However, the TNF-α response was preserved after TLR7/8 (CL097) stimulation, mainly in the neonatal cells. Furthermore, only CL097 activation was able to induce IL-10 and IFN-α secretion in both maternal and CB cells in the infected group. An increase in IFN-α secretion was observed in CL097-treated CB from HIV-infected mothers compared with control mothers. The effectiveness of CL097 stimulation was confirmed by observation of similar mRNA levels of interferon regulatory factor-7 (IRF-7), IFN-α and TNF-α in PBMCs of both groups. The function of both mDCs and pDCs was markedly compromised in the HIV-infected group, and although TLR7/TLR8 activation overcame the impairment in TNF-α secretion by mDCs, such stimulation was unable to reverse the dysfunctional type I IFN response by pDCs in the HIV-infected samples. Our findings highlight the dysfunction of innate immunity in HIV-infected mother-newborn pairs. The activation of the TLR7/8 pathway could function as an adjuvant to improve maternal-neonatal innate immunity.     

Type III Interferons,IL-28 and IL-29, Are Increased in Chronic HCV Infection and Induce Myeloid Dendritic Cell-Mediated FoxP3+ Regulatory T Cells

Background & Aims

Hepatitis C virus (HCV) is difficult to eradicate and type III interferons (IFN-λ, composed of IL-28A, IL-28B and IL-29) are novel therapeutic candidates. We hypothesized that IFN-λ have immunomodulatory effects in HCV- infected individuals.

Materials and Methods

We analyzed the expression of IFN-λ and its receptor (composed of IL-10R2 and IFN-λR subunits) in the blood and livers of patients with chronic (c)HCV infection compared to controls (those who cleared HCV by sustained virological response, SVR, and those with liver inflammation of non-viral origin, non-alcoholic steatohepatitis, NASH). We also compared the proliferative capacity of dendritic cells (DCs) obtained from healthy individuals and those with chronic HCV using a mixed leukocyte reaction combined with 3H-Td incorporation. In addition, the composition of the IFN-λ receptor (IFN-λR) on myeloid DCs, plasmacytoid DCs, PBMCs, and T cells was determined by FACS analysis.

Results

We report that the expression of IFN-λ protein in serum and mRNA in liver is increased in cHCV patients, but not in those with HCV SVR or NASH, compared to controls. Liver level of IFN-λR mirrored the expression of serum IFN-λ and was higher in cHCV, compared to controls and HCV-SVR patients, suggesting that elevation of IFN-λ and IFN-λR are HCV-dependent. We further identified that innate immune cell populations expressed complete IFN-λ receptor. In vitro, recombinant IFN-λ promoted differentiation of monocyte-derived dendritic cells (DCs) into a phenotype with low T cell stimulatory capacity and high PD-L1 expression, which further promoted expansion of existing regulatory T cells. IFN-λ-DCs failed to induce de novo generation of regulatory T cells. The inhibitory capacity of IFN-λ-DCs was counteracted by recombinant IL-12 and by neutralization of the PD-1/PD-L1 system.

Conclusions

Our novel findings of the immunomodulatory effect of IFN-λ contribute to the understanding of the anti-inflammatory and/or anti-viral potential of IFN-λ in cHCV.     

Efficacy of IFN-λ1 to Protect Human Airway Epithelial Cells against Human Rhinovirus 1B Infection

Impaired interferon (IFN) production has been observed in various obstructive respiratory diseases. This contributes to enhanced sensitivity towards viral infections triggering acute exacerbations. To compensate for this impaired host IFN response, there is need to explore new therapeutic strategies, like exogenous administration of IFNs as prophylactic treatment. In the present study, we examined the protective potential of IFN-λ1 and compared it with the previously established protecting effect of IFN-β. A549 cells and human primary bronchial epithelial cells were first treated with either IFN-β (500 IU/ml) or IFN-λ1 (500 ng/ml) for 18 h. For infection, two approaches were adopted: i) Continuous scenario: after pre-treatment, cells were infected immediately for 24 h with human rhinovirus 1B (HRV1B) in IFN-containing medium, or were cultured for another 72 h in IFN-containing medium, and then infected for 24 h with HRV1B, ii) Pre-treatment scenario: IFN-containing medium was replaced after 18 h and cells were infected for 4 h either immediately after pre-treatment or after additional culturing for 72 h in IFN-free medium. The protective effect was evaluated in terms of reduction in the number of viral copies/infectious progeny, and enhanced expression of IFN-stimulated genes (ISGs). In both cell types and in both approaches, IFN-λ1 and IFN-β treatment resulted in pronounced and long-lasting antiviral effects exemplified by significantly reduced viral copy numbers and diminished infectious progeny. This was associated with strong up-regulation of multiple ISGs. However, in contrast to the IFN-β induced expression of ISGs, which decreased over time, expression of ISGs induced by IFN-λ1 was sustained or even increased over time. Here we demonstrate that the protective potential of IFN-λ1 is comparable to IFN-β. Yet, the long-lasting induction of ISGs by IFN-λ1 and most likely less incitement of side effects due to more localized expression of its receptors could make it an even more promising candidate for prophylactic treatment than IFN-β.     

Toll-Like Receptor 8 Agonist and Bacteria Trigger Potent Activation of Innate Immune Cells in Human Liver

The ability of innate immune cells to sense and respond to impending danger varies by anatomical location. The liver is considered tolerogenic but is still capable of mounting a successful immune response to clear various infections. To understand whether hepatic immune cells tune their response to different infectious challenges, we probed mononuclear cells purified from human healthy and diseased livers with distinct pathogen-associated molecules. We discovered that only the TLR8 agonist ssRNA40 selectively activated liver-resident innate immune cells to produce substantial quantities of IFN-γ. We identified CD161^Bright mucosal-associated invariant T (MAIT) and CD56^Bright NK cells as the responding liver-resident innate immune cells. Their activation was not directly induced by the TLR8 agonist but was dependent on IL-12 and IL-18 production by ssRNA40-activated intrahepatic monocytes. Importantly, the ssRNA40-induced cytokine-dependent activation of MAIT cells mirrored responses induced by bacteria, i.e., generating a selective production of high levels of IFN-γ, without the concomitant production of TNF-α or IL-17A. The intrahepatic IFN-γ production could be detected not only in healthy livers, but also in HBV- or HCV-infected livers. In conclusion, the human liver harbors a network of immune cells able to modulate their immunological responses to different pathogen-associated molecules. Their ability to generate a strong production of IFN-γ upon stimulation with TLR8 agonist opens new therapeutic opportunities for the treatment of diverse liver pathologies.     

Deficiency in Th2 Cytokine Responses Exacerbate Orthopoxvirus Infection

Ectromelia virus (ECTV) causes mousepox in mice, a disease very similar to smallpox in humans. ECTV and variola virus (VARV), the agent of smallpox, are closely related orthopoxviruses. Mousepox is an excellent small animal model to study the genetic and immunologic basis for resistance and susceptibility of humans to smallpox. Resistance to mousepox is dependent on a strong polarized type 1 immune response, associated with robust natural killer (NK) cell, cytotoxic T lymphocyte (CTL) and gamma interferon (IFN-γ) responses. In contrast, ECTV-susceptible mice generate a type 2 response, associated with weak NK cell, CTL and IFN-γ responses but robust IL-4 responses. Nonetheless, susceptible strains infected with mutant ECTV lacking virus-encoded IFN-γ binding protein (vIFN-γbp) (ECTV-IFN-γbp^Δ) control virus replication through generation of type 1 response. Since the IL-4/IL-13/STAT-6 signaling pathways polarize type 2/T helper 2 (Th2) responses with a corresponding suppression of IFN-γ production, we investigated whether the combined absence of vIFN-γbp, and one or more host genes involved in Th2 response development, influence generation of protective immunity. Most mutant mouse strains infected with wild-type (WT) virus succumbed to disease more rapidly than WT animals. Conversely, the disease outcome was significantly improved in WT mice infected with ECTV-IFN-γbp^Δ but absence of IL-4/IL-13/STAT-6 signaling pathways did not provide any added advantage. Deficiency in IL-13 or STAT-6 resulted in defective CTL responses, higher mortality rates and accelerated deaths. Deficiencies in IL-4/IL-13/STAT-6 signaling pathways significantly reduced the numbers of IFN-γ producing CD4 and CD8 T cells, indicating an absence of a switch to a Th1-like response. Factors contributing to susceptibility or resistance to mousepox are far more complex than a balance between Th1 and Th2 responses.     

HBsAg Inhibits IFN-α Production in Plasmacytoid Dendritic Cells through TNF-α and IL-10 Induction in Monocytes

Type I Interferon (IFN) is one of the first lines of defense against viral infection. Plasmacytoid dendritic cells (pDCs) are professional IFN-α-producing cells that play an important role in the antiviral immune response. Previous studies have reported that IFN-α production is impaired in chronic hepatitis B (CHB) patients. However, the mechanisms underlying the impairment in IFN-α production are not fully understood. Here, we report that plasma-derived hepatitis B surface antigen (HBsAg) and HBsAg expressed in CHO cells can significantly inhibit toll like receptor (TLR) 9-mediated Interferon-α (IFN-α) production in peripheral blood mononuclear cells (PBMCs) from healthy donors. Further analysis indicated that monocytes participate in the inhibitory effect of HBsAg on pDCs through the secretion of TNF-α and IL-10. Furthermore, TLR9 expression on pDCs was down-regulated by TNF-α, IL-10 and HBsAg treatment. This down-regulation may partially explain the inhibition of IFN-α production in pDCs. In conclusion, we determined that HBsAg inhibited the production of IFN-α by pDCs through the induction of monocytes that secreted TNF-α and IL-10 and through the down-regulation of TLR9 expression on pDCs. These data may aid in the development of effective antiviral treatments and lead to the immune control of the viral infections.