Amb a 1-immunostimulatory oligodeoxynucleotide conjugate immunotherapy decreases the nasal inflammatory response

BACKGROUND

Amb a 1-immunostimulatory phosphorothioate oligonucleotide conjugate (AIC) is a novel immunotherapeutic compound consisting of purified Amb a 1 from short ragweed proteins covalently linked to an immunostimulatory phosphorothioate oligodeoxyribonucleotide. In sensitized animals AIC can stimulate an Amb a 1-specific T(H)1 response and decrease pulmonary reactivity to ragweed challenge. Clinical trials have documented reduced allergic response to AIC in comparison with licensed ragweed extract.

OBJECTIVES

We sought to determine the in vivo effect of short-course immunotherapy with AIC on eosinophilia and cytokine mRNA expression in the nasal mucosa of ragweed-sensitive patients.

METHODS

Ragweed-sensitive patients with allergic rhinitis were treated with 6 escalating doses of AIC (0.06-12 microg, n = 28) or placebo (n = 29) at weekly intervals immediately before the 2001 ragweed season. Symptom scores and medication use were recorded for the 2001 and 2002 ragweed seasons for all patients. A subset of patients (12 receiving AIC and 7 receiving placebo) consented to have nasal biopsy specimens taken before immunization and before and after the first ragweed season. The preseason and postseason biopsy specimens were taken 24 hours after ragweed allergen challenge and compared with the initial unchallenged biopsy specimen to assess cytokine and inflammatory cell responses by using immunocytochemistry and in situ hybridization.

RESULTS

AIC was safe and well tolerated by all patients. There was no difference between the AIC and placebo groups in the number of allergen-induced major basic protein-, IL-4-, IL-5-, or IFN-gamma-positive cells in the mucosa in the first weeks after AIC immunization. On rechallenge and rebiopsy after the end of the 2001 ragweed season, however, AIC-treated patients had a significantly reduced increase in eosinophils and IL-4 mRNA-positive cells and an increased number of IFN-gamma mRNA-positive cells compared with placebo-treated patients. No difference between treatment groups was observed in symptom scores or medication use during the first ragweed season. During the second ragweed season, however, there was a significant decrease in chest symptoms and a trend toward reduced nasal symptoms in the AIC-treated group.

CONCLUSION

Short-course immunotherapy with AIC can modify the response of nasal mucosa to allergen challenge by increasing T(H)1 cytokine production and decreasing T(H)2 cytokine production and eosinophilia. This modification was not immediate but was observed 4 to 5 months after completion of immunotherapy and seasonal ragweed-pollen exposure. The T-cell subset shift after immunization and seasonal exposure was followed by evidence of clinical efficacy in the second ragweed season without additional AIC immunizations.

Differences in innate immune function between allergic and nonallergic children: new insights into immune ontogeny

BACKGROUND

Microbial products are of central interest in the modulation of allergic propensity.

OBJECTIVE

We sought to explore whether allergic children show differences in microbial Toll-like receptor (TLR)-mediated responses over their first 5 years of life.

METHODS

Mononuclear cells isolated from 35 allergic and 35 nonallergic children at birth and 1, 2.5, and 5 years of age were stimulated with TLR2-TLR9 ligands to study innate immune function and with allergens or mitogen to assess adaptive T-cell responses. Cytokine production was measured by using Luminex multiplexing technology.

RESULTS

Nonallergic children show progressive and significant age-related increases in innate cytokine responses (IL-1β, IL-6, TNF-α, and IL-10) to virtually all TLR ligands. This innate maturation corresponds with a parallel increase in adaptive T(H)1 (IFN-γ) responses to allergens and mitogens. In contrast, allergic children show exaggerated innate responses at birth (P < .01) but a relative decrease with age thereafter, so that by age 5 years, TLR responses are attenuated compared with those seen in nonallergic subjects (P < .05). This early hyperresponsiveness in allergic subjects fails to translate to a corresponding maturation of T(H)1 function, which remains attenuated relative to that seen in nonallergic subjects but is associated with a characteristic age-dependent increase in allergen-specific T(H)2 responses (P < .01).

CONCLUSION

Our findings suggest significant differences in the developmental trajectory of innate immune function in children with allergic disease that might contribute to the recognized differences in postnatal adaptive T-cell immunity.

TLR4 polymorphisms mediate impaired responses to respiratory syncytial virus and lipopolysaccharide

Severe bronchiolitis following respiratory syncytial virus (RSV) infection occurs in only a small subset of infected infants and the basis for variations in disease severity is not understood. Innate immune responses to RSV are mediated by TLR-4, and the (299)Gly and (399)Ile alleles of the TLR4 gene have been linked epidemiologically with increased severity of RSV disease in children. We hypothesized that cellular immune responses to RSV mediated by these variant forms of the receptor are defective relative to responses mediated via the common form of the receptor. Human bronchial epithelial cells were transfected with TLR4 constructs encoding the common TLR4 gene sequence ((299)Asp/(399)Thr), or the (299)Gly or (399)Ile alleles, and cytokine responses to in vitro RSV challenge were analyzed in the different transfected cells. Follow-up studies compared RSV-induced responses in PBMC from children expressing these same TLR4 genotypes. Human bronchial epithelial expressing (299)Gly or (399)Ile displayed normal levels of intracellular TLR4 but failed to efficiently translocate the receptor to the cell surface. This was associated with reduced NF-kappaB signaling post-TLR4 engagement, reduced production of IFNs, IL-8, IL-10, IL-12p35, IL-18, and CCL8, and the absence of acute-phase TNF-alpha. These findings were mirrored by blunted PBMC responses to RSV in children expressing the same TLR4 variants. Compromised first-line defense against RSV at the airway-epithelial surface of children expressing these TLR4 variants may thus confer increased susceptibility to severe infections with this virus.

Innate lymphocyte-induced CXCR3B-mediated melanocyte apoptosis is a potential initiator of T-cell autoreactivity in vitiligo

T-cells play a crucial role in progression of autoimmunity, including vitiligo, yet the initial steps triggering their activation and tissue damage remain unknown. Here we demonstrate increased presence of type-1 innate lymphoid cells (NK and ILC1)-producing interferon gamma (IFNγ) in the blood and in non-lesional skin of vitiligo patients. Melanocytes of vitiligo patients have strong basal expression of chemokine-receptor-3 (CXCR3) isoform B which is directly regulated by IFNγ. CXCR3B activation by CXCL10 at the surface of cultured human melanocytes induces their apoptosis. The remaining melanocytes, activated by the IFNγ production, express co-stimulatory markers which trigger T-cell proliferation and subsequent anti-melanocytic immunity. Inhibiting the CXCR3B activation prevents this apoptosis and the further activation of T cells. Our results emphasize the key role of CXCR3B in apoptosis of melanocytes and identify CXCR3B as a potential target to prevent and to treat vitiligo by acting at the early stages of melanocyte destruction.

Lung-gut cross-talk: evidence, mechanisms and implications for the mucosal inflammatory diseases

The mucosal immune system (including airway, intestinal, oral and cervical epithelium) is an integrated network of tissues, cells and effector molecules that protect the host from environmental insults and infections at mucous membrane surfaces. Dysregulation of immunity at mucosal surfaces is thought to be responsible for the alarming global increase in mucosal inflammatory diseases such as those affecting the gastrointestinal (Crohn's disease, ulcerative colitis and irritable bowel syndrome) and respiratory (asthma, allergy and chronic obstructive pulmonary disorder) system. Although immune regulation has been well-studied in isolated mucosal sites, the extent of the immune interaction between anatomically distant mucosal sites has been mostly circumstantial and the focus of much debate. With novel technology and more precise tools to examine histological and functional changes in tissues, today there is increased appreciation of the 'common mucosal immunological system' originally proposed by Bienenstock nearly 40 years ago. Evidence is amounting which shows that stimulation of one mucosal compartment can directly and significantly impact distant mucosal site, however the mechanisms are unknown. Today, we are only beginning to understand the complexity of relationships and communications that exist between different mucosal compartments. A holistic approach to studying the mucosal immune system as an integrated global organ is imperative for future advances in understanding mucosal immunology and for future treatment of chronic diseases. In this review, we particularly focus on the latest evidence and the mechanisms operational in driving the lung-gut cross-talk.

Small airway inflammation in asthma

Asthma was originally described as an inflammatory disease that predominantly involves the central airways. Pathological and physiological evidence reported during the past few years suggests that the inflammatory process extends beyond the central airways to the peripheral airways and the lung parenchyma. The small airways are capable of producing T-helper-2 cytokines, as well as chemokines, and they have recently been recognized as a predominant site of airflow obstruction in asthmatic persons. The inflammation at this distal site has been described as more severe than large airway inflammation. These findings are of great clinical significance, and highlight the need to consider the peripheral airways as a target in any therapeutic strategy for treatment of asthma.

Presence of commensal house dust mite allergen in human gastrointestinal tract: a potential contributor to intestinal barrier dysfunction

BACKGROUND

Abnormal gut barrier function is the basis of gut inflammatory disease. It is known that house dust mite (HDM) aero-allergens induce inflammation in respiratory mucosa. We have recently reported allergen from Dermatophagoides pteronyssinus (Der p1) to be present in rodent gut.

OBJECTIVE

To examine whether Der p1 is present in human gut and to assess its effect on gut barrier function and inflammation.

DESIGN

Colonic biopsies, gut fluid, serum and stool were collected from healthy adults during endoscopy. Der p1 was measured by ELISA. Effect of HDM was assessed on gut permeability, tight-junction and mucin expression, and cytokine production, in presence or absence of cysteine protease inhibitors or serine protease inhibitors. In vivo effect of HDM was examined in mice given oral HDM or protease-neutralised HDM. Role of HDM in low-grade inflammation was studied in patients with IBS.

RESULTS

HDM Der p1 was detected in the human gut. In colonic biopsies from healthy patients, HDM increased epithelial permeability (p<0.001), reduced expression of tight-junction proteins and mucus barrier. These effects were associated with increased tumour necrosis factor (TNF)-α and interleukin (IL)-10 production and were abolished by cysteine-protease inhibitor (p<0.01). HDM effects did not require Th2 immunity. Results were confirmed in vivo in mice. In patients with IBS, HDM further deteriorated gut barrier function, induced TNF-α but failed to induce IL-10 secretion (p<0.001).

CONCLUSIONS

HDM, a ubiquitous environmental factor, is present in the human gut where it directly affects gut function through its proteolytic activity. HDM may be an important trigger of gut dysfunction and warrants further investigation.

Role of toll-like receptor 4 in protection by bacterial lipopolysaccharide in the nasal mucosa of atopic children but not adults

BACKGROUND

Exposure to bacterial products in early life could protect against development of atopy. We examined the effect of bacterial lipopolysaccharide on allergic inflammation and expression of cytokines and lipopolysaccharide receptor (toll-like receptor 4 TLR4) in nasal mucosa of 15 atopic children and ten atopic adults.

METHODS

Explanted mucosa was cultured with allergen with or without lipopolysaccharide (0.1 mg/L) for 24 h. Immunocytochemistry and in-situ hybridisation were used to phenotype the cells and cytokines.

FINDINGS

In explants from atopic children, lipopolysaccharide prevented allergen-induced T-helper type 2 (Th2) inflammation and upregulated Th1 cytokine reactivity and expression. These effects were blocked by antibody to interleukin 10. In children but not in adults, lipopolysaccharide caused increases of three times in T-cell reactivity, five times in T-cell proliferation, and four times in expression of interleukin 10 compared with mucosa stimulated with allergen alone. This difference in response was mirrored by lipopolysaccharide-induced increases in TLR4 reactivity in children but not adults. TLR4 receptor was expressed by CD3-positive T cells, and TLR4-positive cells contained interleukin 10. Lipopolysaccharide increased expression of cells positive for both CD3 and TLR4; both TLR4 and interleukin 10; and both CD4 and CD25.

INTERPRETATION

Lipopolysaccharide inhibits allergic inflammation in nasal mucosa of atopic children by skewing local immune responses from Th2 to Th1 and upregulating production of interleukin 10. These effects are mediated by TLR4. Our results emphasise an important difference between adults and children in their ability to respond to bacterial products. These differences could have a role in normal maturation of the immune system.

Changes in thymic regulatory T-cell maturation from birth to puberty: differences in atopic children

BACKGROUND

Characterization of regulatory immune pathways is a research priority for both the pathogenesis of allergic disease and potential therapeutic strategies.

OBJECTIVE

The thymus is a rich source of regulatory T (Treg) cells, which offers a novel opportunity to document the maturation of these pathways beyond limited studies on small volumes of peripheral blood available from young children.

METHODS

Thymus tissue was collected from children undergoing cardiac surgery (age, 1 week to 14 years), and skin prick testing was performed from 12 months of age. The ontogeny of Treg cell maturation and function was examined in atopic (n = 20) and nonatopic (n = 20) children by assessing their phenotype, enumeration, proliferation, and suppressive ability.

RESULTS

Age-related changes in the thymic cytokine milieu paralleled the changes seen in peripheral immune function. Specifically, the thymic microenvironment is similarly T(H)2 skewed during the early postnatal period, and this undergoes age-related suppression as the T(H)1 (IFN-γ) response increased. We detected CD4(+)CD25(+)CD127(lo/-) forkhead box protein 3 (FOXP3)-positive Treg cells in the neonatal thymus. These cells suppressed the proliferative response to allogeneic stimulation of CD4(+)CD25(-) T cells dose dependently. In nonatopic children Treg cell turnover and suppressive function increased with age and paralleled the increase in global thymic FOXP3 mRNA expression, whereas in atopic children Treg cell maturation was significantly delayed compared with that seen in age-matched nonatopic children.

CONCLUSION

These data suggest that the developmental changes in the thymus parallel the recognized changes in peripheral blood responses. There is also a developmental delay in the function of thymic regulatory cells in atopic compared with nonatopic children. These differences are fundamental to understanding early events that lead to immune dysregulation and might predispose to allergic disease.

New insights into the pathophysiology of the small airways in asthma

Airway inflammation and remodeling in asthma occur in the central airways and also in the small airways and in the lung parenchyma. The small airways and the lung parenchyma can produce many Th2 cytokines, chemokines, and mediators involved in initiation and perpetuation of the inflammatory process. The distal lung has been recognized as a predominant site of airflow obstruction in asthmatics. Distal inflammation has been described as more severe than large airway inflammation, and strong evidence of remodeling in the lung periphery is emerging. Recognition of asthma as a disease of the entire respiratory tract has clinical significance, highlighting the need to target the distal lung in any strategy for effective treatment of this disease.

Thymic indoleamine 2,3-dioxygenase-positive eosinophils in young children: potential role in maturation of the naive immune system

Eosinophils expressing indoleamine 2, 3-dioxygenase (IDO) may contribute to T-helper cell (Th)2 predominance. To characterize human thymus IDO+ eosinophil ontogeny relative to Th2 regulatory gene expression, we processed surgically obtained thymi from 22 children (age: 7 days to 12 years) for immunohistochemistry and molecular analysis, and measured cytokine and kynurenine levels in tissue homogenates. Luna+ eosinophils ( approximately 2% of total thymic cells) decreased in number with age (P = 0.02) and were IDO+. Thymic IDO immunoreactivity (P = 0.01) and kynurenine concentration (P = 0.01) decreased with age as well. In addition, constitutively-expressed interleukin (IL)-5 and IL-13 in thymus supernatants was highest in youngest children. Eosinophil numbers correlated positively with expression of the Th2 cytokines IL-5, IL-13 (r = 0.44, P = 0.002), and IL-4 (r = 0.46, P = 0.005), transcription factor signal transducer and activator of transcription-6 (r = 0.68, P = 0.001), and the chemokine receptor, CCR3 (r = 0.17, P = 0.04), but negatively with IL-17 mRNA (r = -0.57, P = 0.02) and toll-like receptor 4 expression (r = -0.74, P = 0.002). Taken together, these results suggest that functional thymic IDO+ eosinophils during human infant life may have an immunomodulatory role in Th2 immune responses.

T-cell proliferation induced by local application of LPS in the nasal mucosa of nonatopic children

BACKGROUND

Recently, there has been a great deal of interest in the role of bacterial products in altering the allergic immune response in early life.

OBJECTIVE

We sought to develop a model of bacterial inflammation in human subjects to characterize the ex vivo response to LPS in the nasal mucosa of young nonatopic children.

METHODS

Using the explant technique, we cultured nasal mucosa in the presence or absence of increasing concentrations of LPS (0.001-1 microg LPS/mL) for 24 hours. Immunocytochemistry and in situ hybridization were used to phenotype the cells and cytokines in the explant, and immunofluorescence was used to study proliferation of T cells in explants cultured with LPS and 5-bromo-2'-deoxyuridine (BrdU).

RESULTS

CD68, CD3, tryptase, elastase, IFN- gamma IL-12, and IL-10 immunoreactivity was detected in unstimulated tissue. LPS stimulation caused a dose-dependent increase in the number of CD3(+) (n = 7, P <.05), CD68(+) (n = 7, P <.01), elastase-positive (n = 7, P <.01), tryptase-positive (n = 7, P <.05), IL-2 -positive (n = 6, P <.05), IL-12 -positive (n = 6, P <.05), and IFN- gamma-positive (n = 6, P <.05) cells compared with media alone. LPS had no effect on major basic protein, IL-4, IL-5, or IL-13 immunoreactivity. LPS (0.1 microg/mL) caused an increase in the number of BrdU-positive cells as early as 2 hours after incubation (n = 8, P <.001). The maximal BrdU immunoreactivity was seen 24 hours after incubation with LPS, at which time approximately 70% of BrdU- positive cells were CD3(+) T cells.

CONCLUSIONS

Our results suggest that LPS is capable of inducing local inflammation, T(H)1 cytokine immunoreactivity, and proliferation of CD3(+) activated T cells in the absence of de novo cell recruitment. This model holds promise for future studies investigating the importance of bacterial products in regulating local immune function in young atopic children.

Local induction of a specific Th1 immune response by allergen linked immunostimulatory DNA in the nasal explants of ragweed-allergic subjects

BACKGROUND

Allergen immunotherapy is effective in allergic individuals however efforts are being made to improve its safety, convenience, and efficacy. It has recently been demonstrated that allergen-linked immunostimulatory DNA (ISS) is effective in stimulating an allergen-specific Th1 response with decreased allergenicity. The objective of this study is to investigate whether ISS linked to purified ragweed allergen Amb-a-1 (AIC) can inhibit local allergen-specific Th2 and induce allergen-specific Th1 responses in explanted nasal mucosa of ragweed-sensitive subjects. In addition, we set out to determine whether AIC is more effective compared to stimulation with unlinked Amb a 1 and ISS.

METHODS

Tissue from ragweed-sensitive patients (n = 12) was cultured with whole ragweed allergen (RW), Amb-a-1, AIC, Amb-a-1 and ISS (unlinked), or tetanus toxoid (TT) for 24 hours. IL-4, -5, -13, TNF-alpha and IFN-gamma mRNA-positive cells were visualized by in situ hybridization and T cells, B cells and neutrophils were enumerated using immunocytochemistry.

RESULTS

RW or Amb-a-1 increased the number of IL-4, IL-5, and IL-13 mRNA+ cells in the tissue compared to medium alone. AIC had similar cytokine mRNA reactivity as control tissue. AIC and TT increased IFNgamma-mRNA expression. Unlinked Amb-a-1 and ISS showed similar effects to AIC, however this response was weaker. The number of TNF mRNA+ cells, T cells, B cells and neutrophils remained unchanged.

CONCLUSIONS

AIC is effective in stimulating a local allergen-specific Th1- and abolishing Th2-cytokine mRNA reactivity in the nose and may be considered as a strong candidate for an improved approach to immunotherapy in ragweed-sensitive individuals.

Does airway remodelling occur in the upper airways of patients with allergic rhinitis?

Cite this as: M. K. Tulic and Q. Hamid, Clinical & Experimental Allergy, 2010 (40) 1714–1716.

The role of the distal lung in asthma

Accumulating patholological and physiological evidence in the last few years suggests that the airway inflammation and remodeling that characterize asthma occur not only in the central airways but extend to the distal lung and the lung parenchyma. The distal airways are capable of producing T-helper (Th)2 cytokines as well as chemokines, and more recently, they have been recognized as a predominant site of airflow obstruction in asthmatics. A similar TH2-type cytokine profile and infiltration of inflammatory cells has also been reported in the lung parenchyma. The inflammation at this distal site has been described as more severe when compared with the large airway inflammation, and evidence of remodeling in the lung periphery is emerging. Recognition of asthma as a disease of the entire respiratory tract has an important clinical significance highlighting the need also to consider the distal lung as a target in any therapeutic strategy for effective treatment of this disease.

Vitamin D in pregnancy and early life: the right target for prevention of allergic disease?

EVALUATION OF: Weisse et al. Maternal and newborn vitamin D status and its impact on food allergy development in the German LINA cohort study. Allergy 68, 220-228 (2013). Allergic diseases are the most common chronic disorders of childhood. The alarming trend is that these diseases are expressed early in life and are no longer outgrown in childhood. Over the last 10 years, the rates of food allergy and eczema have continued to increase dramatically in children as part of what appears to be a 'second wave' of the allergy epidemic. Although the risk factors for allergic disease are multifactorial, the early onset has implicated lifestyle and environmental factors as significant contributors to this escalating trend. Weisse et al. present supporting evidence for vitamin D being positively associated with children's risk for food allergy or sensitization against food allergens during their first 2 years of life and argue against the use of vitamin D supplements to protect against allergy. Here, the authors provide a mechanistic insight into how high cord blood vitamin D levels can result in increased food allergy risk in children.

Focusing on the Dark Side of the Moon: Involvement of the Nonlesional Skin in Vitiligo

Research over the last decade has revealed that the normally pigmented skin of patients with vitiligo is not normal at all, as evidenced by alterations in cutaneous morphology and modifications in cellular and metabolic functions that ultimately drive immune activation against melanocytes. Furthermore, nonlesional skin is in a state of subclinical inflammation until triggered by internal and/or external exposomal events. Therefore, targeting early processes that drive immune dysregulation in normally pigmented skin may avoid or reduce melanocyte loss. Thus, shifting the focus to nonlesional skin may prevent the appearance of clinical manifestations of the disease rather than treating the lesions.