Ribavirin or CpG DNA sequence-modulated dendritic cells decrease the IgE level and airway inflammation

Precision meets repurposing: Innovative approaches in human papillomavirus and Epstein-Barr virus-driven cancer therapy

Viral malignancies represent a distinct entity among cancers. Oncoviruses like the Human Papilloma Virus (HPV) and the Epstein Barr Virus (EBV) are highly potent inducers of oncogenic transformation leading to tumor development. HPV and EBV are known to be increasingly involved in the pathogenesis of various classes of cancers like cervical, head and neck, colorectal, breast, oral and anogenitial. Therapeutic vaccines directed at such oncoviruses, often fail to unleash the desired immune response against the tumor. This is largely due to the immunosuppressive microenvironment of the virus-induced tumors. Consequently, metronomic chemotherapies administered in conjunction with therapeutic viral vaccines have considerably enhanced the antitumor activity of these vaccines. Moreover, given the unique attributes of HPV and EBV-associated cancers, therapeutic agents directly targeting the oncoproteins of these viruses are still obscure. In this light, an increasing number of reports have evidenced the repurposing of drugs for therapeutic benefits in such cancers. This work delineates the significance and implications of metronomic chemotherapy and drug repurposing in HPV and EBV-associated cancers.

Anti-Inflammatory Activity of Melatonin: a Focus on the Role of NLRP3 Inflammasome

Melatonin is a hormone of the pineal gland that contributes to the regulation of physiological activities, such as sleep, circadian rhythm, and neuroendocrine processes. Melatonin is found in several plants and has pharmacological activities including antioxidant, anti-inflammatory, hepatoprotective, cardioprotective, and neuroprotective. It also has shown therapeutic efficacy in treatment of cancer and diabetes. Melatonin affects several molecular pathways to exert its protective effects. The NLRP3 inflammasome is considered a novel target of melatonin. This inflammasome contributes to enhanced level of IL-1β, caspase-1 activation, and pyroptosis stimulation. The function of NLRP3 inflammasome has been explored in various diseases, including cancer, diabetes, and neurological disorders. By inhibiting NLRP3, melatonin diminishes inflammation and influences various molecular pathways, such as SIRT1, microRNA, long non-coding RNA, and Wnt/β-catenin. Here, we discuss these molecular pathways and suggest that melatonin-induced inhibition of NLRP3 should be advanced in disease therapy.

Immunomodulatory Responses Of Toll Like Receptors Against 2019nCoV

The present review discusses the immune signals via toll like receptors (TLRs) against 2019nCoV. We researched using different database, up to June 18th, 2020. All the included articles were published in English language. The outcome of this review, that some TLRs agonists or antagonists are progressed as drugs to combat and down regulating TLRs immune signals respectively. TLRs 3 and 4 recognized 2019nCoV spike protein through immune and molecular signals that leading to immune stimulation of pro-inflammatory cytokines and even the immune fever. While the TLRs7 and 8 recognized single-stranded ribonucleic acids (ssRNAs) leading to elevation of the tumour necrosis factor α (TNF-α), interleukin (IL)-6 and -12 levels. TLRs agonists or antagonists utilized as immunotherapeutic targets against 2019nCoV via TLRs signals. Chloroquine and hydroxychloroquine; the approval compounds for 2019nCoV therapy can be inhibiting the class II major histocompatibility complex molecules expression and antigen presentation and even immune suppressions of the pro-inflammatory cytokines profile.

Melatonin biosynthesis restored by CpG oligodeoxynucleotides attenuates allergic airway inflammation via regulating NLRP3 inflammasome

AIMS

Both CpG oligodeoxynucleotide (CpG-ODN) and melatonin have been reported to induce Th1 response and contribute to allergic asthma resistance. Here, we aimed to reveal how they confer such effect as well as whether they crosstalk with each other.

MAIN METHODS

Six-week-old Female C57BL/6 mice were challenged by OVA to induce allergic airway inflammation, and were treated with CpG-ODN, CpG-ODN plus Luzindole or melatonin respectively. Bronchoalveolar lavage fluid (BALF) cellularity was classified and counted by Wright's-Giemsa staining. HE and PAS staining were used to analyze airway inflammation. The levels of IL-4, IL-5, IL-13,GM-CSF and IFN-γ, as well as IL-1β and IL-18 were analyzed by ELISA. Protein expressions of ASMT, AANAT, NLRP3, IL-1β and caspase-1 in lung tissue were detected by Western blotting, expression of ASMT and AANAT were further observed by immunohistochemistry.

KEY FINDINGS

We found that CpG-ODN considerably suppressed OVA-induced airway leukocytes infiltration, goblet cell hyperplasia and Th2 cytokines production. Furthermore, the resolution effect of CpG-ODN on OVA-induced allergic airway inflammation occurred in parallel with decreased-activation of NLRP3 inflammasome and increased biosynthesis of melatonin. Blocking the effect of endogenous melatonin by Luzindole abolished the suppressive effect of CpG-ODN on OVA-induced airway inflammation and activation of NLRP3 inflammasome, suggesting such effect was mediated by endogenous melatonin. Moreover, exogenous melatonin pronouncedly ameliorated airway inflammation and decreased the activation of NLRP3 inflammasome.

SIGNIFICANCE

These results proven that CpG-ODN protects against allergic airway inflammation via suppressing the activation of NLRP3 inflammasome, and such effect may be resulted from the restored-production of melatonin.

TLRs in pulmonary diseases

Toll-like receptors (TLRs) comprise a clan of proteins involved in identification and triggering a suitable response against pathogenic attacks. As lung is steadily exposed to multiple infectious agents, antigens and host-derived danger signals, the inhabiting stromal and myeloid cells of the lung express an aggregate of TLRs which perceive the endogenously derived damage-associated molecular patterns (DAMPs) along with pathogen associated molecular patterns (PAMPs) and trigger the TLR-associated signalling events involved in host defence. Thus, they form an imperative component of host defence activation in case of microbial infections as well as non-infectious pulmonary disorders such as interstitial lung disease, acute lung injury and airways disease, such as COPD and asthma. They also play an equally important role in lung cancer. Targeting the TLR signalling network would pave ways to the design of more reliable and effective vaccines against infectious agents and control deadly infections, desensitize allergens and reduce inflammation. Moreover, TLR agonists may act as adjuvants by increasing the efficiency of cancer vaccines, thereby contributing their role in treatment of lung cancer too. Overall, TLRs present a compelling and expeditiously bolstered area of research and addressing their signalling events would be of significant use in pulmonary diseases.

Holding the Inflammatory System in Check: TLRs and Their Targeted Therapy in Asthma

Inflammation is a complex biological response to detrimental stimuli and can be a double-edged sword. Inflammation plays a protective role in removing pathogenic factors, but dysregulated inflammation is associated with several major fatal diseases such as asthma, cancer, and cardiovascular diseases. Asthma is a complex heterogenous disease caused by genetic and environmental factors. TLRs are the primary proteins associated with the innate and adaptive immune responses to these fatal factors and play an important role in recognizing pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs), which initiates the downstream immune response. Due to the complex TLRs cascade and nowadays unsuccessful control in asthma, new studies are focused on TLRs and other potential targets in TLR cascade to minimize airway inflammation.

Oral administration of heat-inactivated Lactobacillus plantarum K37 modulated airway hyperresponsiveness in ovalbumin-sensitized BALB/c mice

This study aimed to investigate the anti-allergic effects of Lactobacillus plantarum K37 (K37) on airway hyperresponsiveness (AHR) and systemic allergic responses in ovalbumin (OVA)-sensitized and -challenged BALB/c mice. Heat-inactivated K37 (10⁵, 10⁷, and 10⁹ CFU/mouse, day) were orally administered to OVA-sensitized BALB/c mice to investigate their effects on AHR, immunoglobulin (Ig) and cytokine production. The results showed that K37 dose-dependently lowered the serum levels of IgE, OVA-specific IgE and OVA-specific IgG1, ameliorated AHR induced by methacholine and suppressed eosinophil infiltration in bronchoalveolar lavage fluid (BALF). The cytokine production in spleen cells culture and BALF showed that K37 drove the immune responses toward T-helper cell type 1 (Th1) responses, elevated levels of IL-2 and IFN-γ, and reduced of IL-4, IL-5 and IL-13. K37 also improved cell infiltration in lung sections. Our results demonstrated that oral administration of K37 alleviated effectively the allergic responses invivo. Thus, K37 can be a good source material and a promising candidate for prophylactic and therapeutic treatments of allergic diseases, like asthma.

A new era of targeting the ancient gatekeepers of the immune system: toll-like agonists in the treatment of allergic rhinitis and asthma

Toll-like receptors (TLR) belong to a large family of pattern recognition receptors known as the ancient 'gatekeepers' of the immune system. TLRs are located at the first line of defense against invading pathogens as well as aeroallergens, making them interesting targets to modulate the natural history of respiratory allergy. Agonists of TLRs have been widely employed in therapeutic or prophylactic preparations useful for asthma/allergic rhinitis (AR) patients. MPL® (a TLR4 agonist) and the CpG oligodeoxynucleotide of 1018 ISS, a TLR9 agonist, show strong immunogenicity effects that make them appropriate adjuvants for allergy vaccines. Targeting the TLRs can enhance the efficacy of specific allergen immunotherapy, currently the only available 'curative' treatment for respiratory allergies. In addition, intranasal administration of AZD8848 (a TLR7 agonist) and VTX-1463 (a TLR8 agonist) as stand-alone therapeutics have revealed efficacy in the relief of the symptoms of AR patients. No anaphylaxis has been so far reported with such compounds targeting TLRs, with the most common adverse effects being transient and local irritation (e.g. redness, swelling and pruritus). Many other compounds that target TLRs have been found to suppress airway inflammation, eosinophilia and airway hyper-responsiveness in various animal models of allergic inflammation. Indeed, in the future a wide variability of TLR agonists and even antagonists that exhibit anti-asthma/AR effects are likely to emerge.

Assessment of the effect of ribavirin on myeloid and plasmacytoid dendritic cells during interferon-based therapy of chronic hepatitis B patients

The combination of ribavirin and peginterferon is the current standard of anti-viral treatment for chronic HCV patients. However, little is known on the mode of action of ribavirin in the anti-viral treatment of HCV patients. To investigate the immunomodulatory mechanism of ribavirin, we studied peginterferon alone versus peginterferon and ribavirin in chronic HBV patients. The addition of ribavirin did not affect the number of myeloid dendritic cells (mDC) or plasmacytoid dendritic cells (pDC), nor did it enhance T-helper-1 cell activity or T-cell proliferation. In contrast, it increased upregulation of activation markers on mDC and pDC, which was sustained throughout treatment. However, the addition of ribavirin had no effect on IFNα production by pDC. Our findings demonstrate that, although ribavirin does not lead to a viral load decline, in vivo treatment with ribavirin affects the activation of pDC and mDC in chronic HBV patients.

Pharmacology and therapeutic potential of pattern recognition receptors

Pharmacologists have used pathogen-associated molecular patterns (PAMPs), such as lipopolysaccharide (LPS) for decades as a stimulus for studying mediators involved in inflammation and for the screening of anti-inflammatory compounds. However, in the view of immunologists, LPS was too non-specific for studying the mechanisms of immune signalling in infection and inflammation, as no receptors had been identified. This changed in the late 1990s with the discovery of the Toll-like receptors. These 'pattern recognition receptors' (PRRs) were able to recognise highly conserved sequences, the so called pathogen associated molecular patterns (PAMPs) present in or on pathogens. This specificity of particular PAMPs and their newly defined receptors provided a common ground between pharmacologists and immunologists for the study of inflammation. PRRs also recognise endogenous agonists, the so called danger-associated molecular patterns (DAMPs), which can result in sterile inflammation. The signalling pathways and ligands of many PRRs have now been characterised and there is no doubt that this rich vein of research will aid the discovery of new therapeutics for infectious conditions and chronic inflammatory disease.

Ribavirin as an anti-cancer therapy: acute myeloid leukemia and beyond?

Ribavirin was discovered nearly 40 years ago as a broad-spectrum antiviral drug. Recent data suggest that ribavirin may also be an effective cancer therapy. In this case, ribavirin targets an oncogene, the eukaryotic translation initiation factor eIF4E, elevated in approximately 30% of cancers including many leukemias and lymphomas. Specifically, ribavirin impedes eIF4E mediated oncogenic transformation by acting as an inhibitor of eIF4E. In a phase II clinical trial, ribavirin treatment led to substantial clinical benefit in patients with poor-prognosis acute myeloid leukemia (AML). Here molecular targeting of eIF4E correlated with clinical response. Ribavirin also targets a key enzyme in the guanosine biosynthetic pathway, inosine monophosphate dehydrogenase (IMPDH), and also modulates immunity. Parallels with known antiviral mechanisms could be informative; however, after 40 years, these are not entirely clear. The antiviral effects of ribavirin appear cell-type specific. This variation likely arises for many reasons, including cell specific variations in ribavirin metabolism as well as virus specific factors. Thus, it seems that the mechanisms for ribavirin action in cancer therapy may also vary in terms of the cancer/tissue under study. Here we review the anticancer activities of ribavirin and discuss the possible utility of incorporating ribavirin into diverse cancer therapeutic regimens.

Oligonucleotide based-strategies for allergy with special reference to siRNA

BACKGROUND

Allergic diseases are a significant global health care problem. Current pharmacological approaches address symptoms but do not alter the underlying immune dysregulation. Current allergen-specific immunotherapy has several drawbacks. Therefore, approaches that attenuate allergic responses safely and effectively at the level of upstream causative events are desirable. Oligonuleotide-based therapies [CpG DNA, antisense oligonucleotides, and small interfering RNA (siRNA)] are promising approaches.

OBJECTIVE/METHODS

We review developments in oligonucleotide-based therapies and the potential of siRNA for treating allergy.

RESULTS/CONCLUSIONS

Strategies with oligonucleotides basically aim to reduce T helper type 2 (Th2) responses. It is controversial whether the reduction of Th2 responses does, in fact, attenuate allergic diseases. Increased understanding of allergic mechanisms will enhance the efficacy of oligonucleotide-based therapy.

Administration of polysaccharides from Antrodia camphorata modulates dendritic cell function and alleviates allergen-induced T helper type 2 responses in a mouse model of asthma

Asthma is a chronic disease characterized by airway inflammation caused by the dysregulated production of cytokines secreted by allergen-specific type 2 T helper (Th2) cells. Antrodia camphorata is a commonly used fungus in Asian folk medicine, and A. camphorata polysaccharides are reported to possess anti-cancer activities. In this study, the immunomodulatory effects of purified fractionated polysaccharides (GF2) from A. camphorata on dendritic cells (DCs) and their potential preventive effects against ovalbumin (OVA) -induced asthma were investigated. In the presence of GF2, lipopolysaccharide (LPS) -activated DCs exhibited up-regulated expression of major histocompatibility complex (MHC) class II and co-stimulatory molecules, as well as enhanced interleukin-10 (IL-10) and IL-12 production. GF2 treatment on LPS-activated DCs suppressed naïve CD4(+) T-cell proliferation and Th2 cell polarization with IL-10 production in an allogeneic mixed lymphocyte reaction. In animal experiments, a high dose of GF2 efficiently reduced expression levels of OVA-specific immunoglobulin G1 (IgG1) and IgE. However, lower doses of GF2 significantly enhanced OVA-specific IgG2a production. Our data also showed that administration of GF2 dose-dependently inhibited the development of airway hyperresponsiveness, airway eosinophilia and Th2 responses. OVA-specific CD4(+) T cells from higher doses of GF2-treated mice had significantly lower proliferative capacities compared with control mice. Moreover, treatment with GF2 significantly increased the high levels of IL-10 and low levels of interferon-gamma produced by T cells. Taken together, these data indicate that administration of A. camphorata polysaccharides (GF2) may have therapeutic potential when used as an adjuvant for the immunomodulatory treatment of allergic asthma.

Ribavirin for respiratory syncytial virus bronchiolitis reduced the risk of asthma and allergen sensitization

Respiratory syncytial virus (RSV) bronchiolitis in early life is a risk factor for later development of asthma and atopy. Ribavirin is the only effective drug currently available against acute RSV bronchiolitis. However, the long-term effects of ribavirin remain unclear. We investigated a cohort of children hospitalized with RSV bronchiolitis from when they were under 2 yr old until they reached a mean age of 6.2 yr. In total, we enrolled 175 children in this study. Both the group treated with ribavirin and the group not treated with ribavirin included high-risk young children with congenital heart disease or chronic lung disease. Their respective age-matched controls, that we labeled groups A and B, both without ribavirin treatment, consisted of previously healthy subjects. Wheezing was either verified by physicians or estimated by a questionnaire. Allergen sensitization was judged by serum allergen-specific IgE levels. The cumulative incidence of physician-diagnosed asthma or recurrent wheezing in the ribavirin group (15%) was significantly lower than its incidence in the non-ribavirin-treated group (34%, p = 0.049), and in the control A group (43%, p = 0.005). Allergen sensitization was also least frequent in the ribavirin group. Ribavirin therapy was an independent factor in reducing the risk of developing asthma, asthma/recurrent wheezing, and sensitization to D. pteronyssinus/D. farinae. The long-term value of ribavirin for acute RSV bronchiolitis and its underlying mechanisms deserves further research.

Dendritic cells in allergic airway inflammation

Dendritic cells (DCs) are primary antigen-presenting cells involved in interactions with T cells leading to the proliferation of TH1 or TH2 cell types. In asthma, predominance of TH2 cells appears to be responsible for disease pathogenesis. Differentiation of TH2 cells is driven by a variety of factors such as the expression of high levels of costimulatory molecules, the cytokine profile, and the subset of DCs. Many inflammatory cells involved in the pathogenesis of asthma either directly or indirectly modulate DC function. Traditional treatments for asthma decrease the number of airway DCs in animals as well as in patients with asthma. Immunomodulators including interleukin (IL)-10, transforming growth factor (TGF)-beta, cytosine-phosphate-guanosine-containing oligodeoxynucleotides (CpG-ODN), 1alpha,25-dihydroxyvitamin D3, and fetal liver tyrosine kinase 3 ligand (Flt3L) are involved in the modulation of the function of DCs. Based on the critical review of the interaction between DCs and other inflammatory cells, we propose that activation of T cells by DCs and sensitization to inhaled allergen and resulting airway inflammation are dependent on plasmacytoid and myeloid subset of lung DCs to induce an immune response or tolerance and are tightly regulated by T-regulatory cells. Effects of various therapeutic agents to modulate the function of lung myeloid DCs have been discussed.

Immunostimulatory oligonucleotides in therapy of allergic diseases

At present, the improvement of hygienic life standards is considered as an environmental condition, increasing the prevalence of allergic diseases, as early contact with some pathogens is, according to the hygiene hypothesis, required for maturation of the immune system. The recognition of microbial components involves acquired and innate immunity mechanisms. Recently, the link between innate and acquired immunity has been discovered. It involves the evolutionarily old Toll-like receptor (TLR) system. Ligands recognised by TLRs include unmethylated deoxycytidil-deoxyguanosine (CpG) motif-containing microbial DNA. TLR-mediated signalling induces expression of cytokines preferentially promoting a Th1-directed response. Therefore, synthetic CpG motif-containing immunostimulatory oligonucleotides could be employed in causal allergy treatment. This review discusses some molecular aspects of the TLR system, as well as results of animal studies and early experiences, including treatment safety, from human clinical trials with immunostimulatory CpG motif-containing oligonucleotides.

Fas-ligand-expressing adenovirus-transfected dendritic cells decrease allergen-specific T cells and airway inflammation in a murine model of asthma

T cells expressing a type-2 T helper profile of cytokines (Th2 cells) have been demonstrated to play an important role in the initiation and progression of allergic asthma, and it is well known that Fas ligand (FasL) induces apoptosis when bound to its receptor, Fas. In the present study, we examined the possibility of modulating asthma manifestations by dendritic cells (DCs) genetically engineered to express FasL (DC-FasL), which could deliver a death signal to T cells in an antigen-specific manner. The delivery of DC-FasL into ovalbumin (OVA)-immunized allergic mice decreased the airway hyper-responsiveness (AHR). Moreover, we established a mouse model of airway inflammation by using an adoptive transfer of Th2 cells derived from ovalbumin T cell receptor transgenic mice to study the effect of DC-FasL on airway reactivity. The administration of DC-FasL in Th2-cell-induced allergic mice had significantly decreased AHR, airway inflammation, and IL-4, IL-5 and IL-13 production. Furthermore, the numbers of OVA-specific T cells were decreased in the lung of mice receiving DC-FasL. These results demonstrate that FasL-expressing dendritic cells might be applied for the modulation of allergic responses.

Targeting memory Th2 cells for the treatment of allergic asthma

Th2 memory cells play an important role in the pathogenesis of allergic asthma. Evidence from patients and experimental models indicates that memory Th2 cells reside in the lungs during disease remission and, upon allergen exposure, become activated effectors involved in disease exacerbation. The inhibition of memory Th2 cells or their effector functions in allergic asthma influence disease progression, suggesting their importance as therapeutic targets. They are allergen specific and can potentially be suppressed or eliminated using this specificity. They have distinct activation, differentiation, cell surface phenotype, migration capacity, and effector functions that can be targeted singularly or in combination. Furthermore, memory Th2 cells residing in the lungs can be treated locally. Capitalizing on these unique attributes is important for drug development for allergic asthma. The aim of this review is to present an overview of therapeutic strategies targeting Th2 memory cells in allergic asthma, emphasizing Th2 generation, differentiation, activation, migration, effector function, and survival.

Mice vaccinated with allergen-pulsed myeloid dendritic cells are not protected from developing allergen-induced Th2 responses

BACKGROUND

Dendritic cells (DC) play a decisive role in the induction of allergen-induced Th1 and Th2 responses. Since the induction of allergen-specific Th1 responses has shown to inhibit allergen-induced Th2-type inflammation, in this study we investigated whether manipulated myeloid-derived DC pulsed with the specific allergen would predominantly induce allergen-specific Th1 responses thereby reducing the development of Th2 responses.

METHODS

Murine bone marrow (BM)-DC were generated and pulsed with ovalbumin (OVA) and CpG oligodeoxynucleotides (CpG-ODN). Langerhans cells (LC) were also isolated and pulsed in vitro with OVA. Subsequently, mice were vaccinated intravenously with either CpG/OVA-pulsed BM-DC or OVA-pulsed LC, and the protocol to induce OVA-specific Th2 responses using OVA/alum sensitization was initiated. Airway inflammation and OVA-specific serum antibody levels were evaluated 6 days after the intranasal challenge with OVA.

RESULTS

The application ofCpG/OVA-pulsed BM-DC was unable to reduce airway eosinophilia and inflammation in OVA/alum-immunized mice. OVA-specific IgG1 or IgE serum levels were also not reduced. The experiments using LC pulsed with OVA yielded similar results. However, mice vaccinated with CpG/OVA-pulsed BM-DC had greatly enhanced levels of serum OVA-specific IgG2a, suggesting the induction of allergen-specific Th1 responses in vivo. Moreover, allergen-induced mast cell degranulation was decreased using this approach.

CONCLUSIONS

Taken together, our results demonstrated that the vaccination with OVA-pulsed BM-DC matured with CpG-ODN or OVA-pulsed LC did not result in a reduction in allergen-specific Th2 responses in a murine model of severe atopic asthma. Other DC-based vaccination strategies should be evaluated in order to prevent the development of allergic disorders.

Immunomodulation in asthma: a distant dream or a close reality?

The search for new treatments of asthma or any other disease for that matter is an infinite exercise. The scope for discovering new forms of treatment has increased now more than ever due to a better understanding of the molecular pathogenesis of the disease. Regulation of biomolecular or immunological events could occur at numerous points in the disease pathogenesis. This review describes the strategies to regulate the inappropriate immune responses that are elicited after exposure to an allergen. One such successful therapy is treatment with omalizumab, the anti-IgE antibody. Other therapies include cytokine antagonists, transcription factor antagonists, immunostimulatory DNA therapy, cytokine therapy and anti-T cell strategies. All these agents have been shown to be promising and could serve as an alternative approach to the treatment of asthma and maybe other allergic diseases.

CpG DNA: immunomodulation and remodelling of the asthmatic airway

Asthma is a disorder of increasing severity and prevalence. Present understanding of the pathogenesis of asthma emphasises its inflammatory nature. Unbridled inflammation appears to induce irreversible changes, collectively known as airway remodelling. CpG oligonucleotides are a class of compounds that have been developed from studies of prokaryotic DNA. Bacterial DNA, for example, contains sequence motifs based on the dinucleotides cytosine-guanine (CpG); these motifs are suppressed in mammalian DNA and induce (as part of the innate immune system) inflammation, characterised by the induction of T helper type 1 and regulatory responses. The pattern of inflammation promoted by CpG DNA tends to suppress the cytokine and cellular responses characteristic of asthma and atopic disorders. This has led to the investigation and development of CpG DNA as a novel therapeutic approach for the treatment and prevention of these disorders. In addition to suppressing acute and persistent airway inflammation, CpG DNA also reduces the development of subepithelial collagen deposition, goblet cell hyperplasia/metaplasia, and other aspects of airway remodelling. In this paper, the effects of CpG DNA on asthma inflammation and remodelling are reviewed.

Th1/Th2 cells in inflammatory disease states: therapeutic implications

Inflammation is initiated as a protective response by the host, but can often result in systemic pathology. Among cells of the immune system, T lymphocytes play a major role in the inflammatory response. T cell inflammation is characterised histologically by an infiltration of mononuclear cells. Key regulators of this response are a subset of T lymphocytes called T helper (Th) cells. These cells secrete soluble mediators called cytokines, which orchestrate the immune response. The appropriate regulation of Th cell immunity is critical in the control and prevention of diverse disease states. This review will focus on the role of Th cells in the inflammatory process involved in allergic disease, diabetes, infectious disease, rheumatoid arthritis, heart disease, multiple sclerosis and cancer. In the area of autoimmunity, in particular, a basic understanding of Th cells and cytokines has contributed to the development of clinically efficacious biological agents. This review also examines current and novel treatment strategies under investigation at present that regulate Th cell immunity, which may result in better treatments for immune-mediated diseases.

Modulation of ovalbumin-induced Th2 responses by second-generation immunomodulatory oligonucleotides in mice

Oligodeoxynucleotides containing unmethylated CpG dinucleotides (CpG DNAs) prevent development of T-helper type 2 (Th2) immune responses and reverse established allergic responses in mouse models. We recently reported that second-generation immunomodulatory oligonucleotides (IMOs) containing novel structures (immunomers) and a synthetic immunostimulatory CpR (R=2'-deoxy-7-deazguanosine) motif induce the production of distinct cytokine secretion profiles in vitro and in vivo. In the present study, we evaluated IMOs containing CpG and CpR motifs to modulate allergen-induced Th2 immune responses in prevention and treatment models. Mice sensitized and challenged with ovalbumin (OVA) were treated with a CpG DNA or an IMO by administration either at the time of OVA sensitization (co-administration; prevention) or after establishment of an allergic response (treatment). Spleens, blood, and lungs were collected and analyzed for immune responses. Spleen-cell cultures harvested from OVA-sensitized mice showed a significant decrease in Th2 cytokine levels with a concomitant increase in Th1 cytokine levels only when CpG DNA or IMOs were co-administered with OVA. The co-administration of CpG DNA or IMOs during OVA sensitization significantly reduced serum OVA-specific and total IgE levels in mice. The mice who received CpG DNA or IMOs co-administered with OVA showed a small reduction in serum OVA-specific and total IgG1 levels and a significant increase in serum OVA-specific and total IgG2a levels. Similar results were found in mice with established allergic responses who received IMO treatment. IMO treatment also resulted in strong inhibition of inflammatory cell infiltration and goblet cell hyperplasia in the lungs compared with untreated mice lungs. These data demonstrate that IMOs prevent antigen-induced Th2 immune responses when co-administered to mice during OVA sensitization and that IMOs reverse established allergic responses induced by OVA.

Adenovirus expressing Fas ligand gene decreases airway hyper-responsiveness and eosinophilia in a murine model of asthma

Allergic asthma is characterized by airway hyper-responsiveness (AHR) and cellular infiltration of the airway with predominantly eosinophils and Th2 cells. The normal resolution of inflammation in the lung occurs through the regulated removal of unneeded cells by Fas-Fas ligand-mediated apoptosis. Fas ligand (FasL) is a member of the tumor necrosis factor family, and when bound to Fas, it induces apoptosis of the cells. To examine the effect of the FasL gene on airway inflammation and immune effector cells in allergic asthma, recombinant adenovirus expressing murine FasL (Ad-FasL) was delivered intratracheally into ovalbumin (OVA)-immunized mice. We found that a single administration of Ad-FasL in OVA-immunized mice significantly alleviated AHR and eosinophilia by inducing the apoptosis of eosinophils and/or reducing eosinophil attractant factors, such as IL-5 and eotaxin levels. The number of infiltrated lymphocytes and Th2 cytokines, including IL-5 and IL-13, decreased in OVA-immunized mice by administration of Ad-FasL. KC and TNF-alpha production also decreased in Ad-FasL-treated OVA-immunized mice. These findings indicated that the administration of Ad-FasL to OVA-sensitized mice significantly suppressed pulmonary allergic responses. Although more studies are needed, these results suggested that Ad-FasL might be applied as an alternative therapy for allergic asthma.

Dendritic cells modulated by cytokine-expressing adenoviruses alleviate eosinophilia and airway hyperresponsiveness in an animal model of asthma

BACKGROUND

It has been found that TH1-related cytokines can decrease the accumulation of eosinophils in lung tissue and relieve airway constriction.

OBJECTIVE

Dendritic cells (DCs) have been found to prime naive T-helper cells efficiently. In this study, DCs infected with TH1 cytokine-expressing adenovirus can be used to induce antigen-specific TH1 cells for treatment in an animal model of asthma.

METHODS

Cytokine gene-modulated DCs pulsed with ovalbumin antigen (OVA) were injected intravenously into naive mice 1 week before sensitization with OVA antigen. The mice were then monitored for OVA-specific IgE, airway inflammatory cell infiltration, and airway hyperresponsiveness in the study.

RESULTS

Significant levels of IL-12 or IL-18 were expressed by Ad-IL-12 or Ad-IL-18 infected, bone marrow-derived DCs. Ad-IL-12 and Ad-IL-18 co-infected DCs effectively, decreasing sera anti-OVA IgE antibody levels, lung eosinophilia, and airway hyperresponsiveness.

CONCLUSION

We concluded that DCs modulated by TH1-prone cytokine-expressing adenoviruses can alleviate TH2-type airway inflammation in a murine model and can provide possible therapeutic application for DCs in asthma.