Kayhan T. Nouri-Aria

Long-term clinical efficacy of grass-pollen immunotherapy.

BACKGROUND Pollen immunotherapy is effective in selected patients with IgE-mediated seasonal allergic rhinitis, although it is questionable whether there is long-term benefit after the discontinuation of treatment. METHODS We conducted a randomized, double-blind, placebo-controlled trial of the discontinuation of immunotherapy for grass-pollen allergy in patients in whom three to four years of this treatment had previously been shown to be effective. During the three years of this trial, primary outcome measures were scores for seasonal symptoms and the use of rescue medication. Objective measures included the immediate conjunctival response and the immediate and late skin responses to allergen challenge. Cutaneous-biopsy specimens obtained 24 hours after intradermal allergen challenge were examined for T-cell infiltration and the presence of cytokine-producing T helper cells (TH2 cells) (as evidenced by the presence of interleukin-4 messenger RNA). A matched group of patients with hay fever who had not received immunotherapy was followed as a control for the natural course of the disease. RESULTS Scores for seasonal symptoms and the use of rescue antiallergic medication, which included short courses of prednisolone, remained low after the discontinuation of immunotherapy, and there was no significant difference between patients who continued immunotherapy and those who discontinued it. Symptom scores in both treatment groups (median areas under the curve in 1995, 921 for continuation of immunotherapy and 504 for discontinuation of immunotherapy; P=0.60) were markedly lower than those in the group that had not received immunotherapy (median value in 1995, 2863). Although there was a tendency for immediate sensitivity to allergen to return late after discontinuation, there was a sustained reduction in the late skin response and associated CD3+ T-cell infiltration and interleukin-4 messenger RNA expression. CONCLUSIONS Immunotherapy for grass-pollen allergy for three to four years induces prolonged clinical remission accompanied by a persistent alteration in immunologic reactivity.

Grass Pollen Immunotherapy Induces Mucosal and Peripheral IL-10 Responses and Blocking IgG Activity

T regulatory cells and IL-10 have been implicated in the mechanism of immunotherapy in patients with systemic anaphylaxis following bee stings. We studied the role of IL-10 in the induction of clinical, cellular, and humoral tolerance during immunotherapy for local mucosal allergy in subjects with seasonal pollinosis. Local and systemic IL-10 responses and serum Ab concentrations were measured before/after a double-blind trial of grass pollen (Phleum pratense, Phl P) immunotherapy. We observed local increases in IL-10 mRNA-positive cells in the nasal mucosa after 2 years of immunotherapy, but only during the pollen season. IL-10 protein-positive cells were also increased and correlated with IL-10 mRNA+ cells. These changes were not observed in placebo-treated subjects or in healthy controls. Fifteen and 35% of IL-10 mRNA signals were colocalized to CD3+ T cells and CD68+ macrophages, respectively, whereas only 1–2% of total CD3+ cells and 4% of macrophages expressed IL-10. Following immunotherapy, peripheral T cells cultured in the presence of grass pollen extract also produced IL-10. Immunotherapy resulted in blunting of seasonal increases in serum allergen Phl p 5-specific IgE, 60- to 80-fold increases in Phl p 5-specific IgG, and 100-fold increases in Phl p 5-specific IgG4. Post-immunotherapy serum exhibited inhibitory activity, which coeluted with IgG4, and blocked IgE-facilitated binding of allergen-IgE complexes to B cells. Both the increases in IgG and the IgG “blocking” activity correlated with the patients’ overall assessment of improvement. Thus, grass pollen immunotherapy may induce allergen-specific, IL-10-dependent “protective” IgG4 responses.

Grass pollen immunotherapy induces Foxp3-expressing CD4+CD25+ cells in the nasal mucosa

BACKGROUND Regulatory T (Treg) cells play an important role in controlling allergic inflammation. The transcription factor Foxp3 regulates the development and function of natural and adaptive CD4(+)CD25(+) Treg cells. OBJECTIVES We sought to examine the effect of grass pollen injection immunotherapy on the numbers of Foxp3(+)CD4(+) and Foxp3(+)CD25(+) T cells in and out of season and their expression of IL-10 in the nasal mucosa of patients with hay fever. METHODS Nasal biopsy specimens were obtained from untreated patients with hay fever, participants with grass pollen allergy who had received 2 years of immunotherapy, and healthy control subjects. Dual-immunofluorescence microscopy was used to enumerate and colocalize Foxp3 expression to CD4(+) and CD25(+) T cells in the nasal mucosa. Triple staining was performed to colocalize Foxp3(+) cells to CD3(+)CD25(+) and CD3(+) IL-10-expressing cells. RESULTS At peak season, numbers of Foxp3(+)CD25(+) (P = .02) and Foxp3(+)CD4(+) (P = .03) cells were significantly increased in the nasal mucosa of immunotherapy-treated patients compared with numbers before treatment. Foxp3(+)CD25(+) (P = .03) and Foxp3(+)CD4(+) (P = .04) cells were also greater in immunotherapy-treated patients out of season compared with those in untreated patients with hay fever. Within the immunotherapy-treated group, 20% of CD3(+)CD25(+) cells expressed Foxp3, and 18% of Foxp3(+)CD3(+) cells were IL-10 positive. CONCLUSION The presence of local Foxp3(+)CD25(+)CD3(+) cells in the nasal mucosa, their increased numbers after immunotherapy, and their association with clinical efficacy and suppression of seasonal allergic inflammation support a putative role for Treg cells in the induction of allergen-specific tolerance in human subjects.

Sublingual grass pollen immunotherapy is associated with increases in sublingual Foxp3-expressing cells and elevated allergen-specific immunoglobulin G4, immunoglobulin A and serum inhibitory activity for immunoglobulin E-facilitated allergen binding to B cells

Background The mechanisms of sublingual immunotherapy (SLIT) are less well understood than those of subcutaneous immunotherapy (SCIT).

Grass pollen sublingual immunotherapy for seasonal rhinoconjunctivitis: a randomized controlled trial

Background Previous studies suggest that sublingual immunotherapy (SLIT) represents a safer alternative to injection immunotherapy but equivalent efficacy is yet to be confirmed.

Grass Pollen Immunotherapy Induces an Allergen-Specific IgA2 Antibody Response Associated with Mucosal TGF-β Expression

Allergen immunotherapy (IT) has long-term efficacy in IgE-mediated allergic rhinitis and asthma. IT has been shown to modify lymphocyte responses to allergen, inducing IL-10 production and IgG Abs. In contrast, a putative role for IgA and local TGF-β-producing cells remains to be determined. In 44 patients with seasonal rhinitis/asthma, serum IgA1, IgA2, and polymeric (J chain-containing) Abs to the major allergen Phl p 5 were determined by ELISA before and after a 2-year double-blind trial of grass pollen (Phleum pratense) injection IT. Nasal TGF-β expression was assessed by in situ hybridization. Sera from five IT patients were fractionated for functional analysis of the effects of IgA and IgG Abs on IL-10 production by blood monocytes and allergen-IgE binding to B cells. Serum Phl p 5-specific IgA2 Abs increased after a 2-year treatment (∼8-fold increase, p = 0.002) in contrast to IgA1. Increases in polymeric Abs to Phl p 5 (∼2-fold increase, p = 0.02) and in nasal TGF-β mRNA (p = 0.05) were also observed, and TGF-β mRNA correlated with serum Phl p 5 IgA2 (r = 0.61, p = 0.009). Post-IT IgA fractions triggered IL-10 secretion by monocytes while not inhibiting allergen-IgE binding to B cells as observed with IgG fractions. This study shows for the first time that the IgA response to IT is selective for IgA2, correlates with increased local TGF-β expression, and induces monocyte IL-10 expression, suggesting that IgA Abs could thereby contribute to the tolerance developed in IT-treated allergic patients.

Grass pollen immunotherapy for hayfever is associated with increases in local nasal but not peripheral Th1 : Th2 cytokine ratios

Grass pollen immunotherapy is the only treatment for hayfever that is both effective and confers long‐term benefit. Immunotherapy may act by altering the local nasal mucosal T helper type 2 (Th2) to type 1 (Th1) cytokine balance either by down‐regulation and/or immune deviation of T‐lymphocyte responses. There is controversy as to whether these changes are detectable in peripheral blood. We therefore examined both local nasal and peripheral T‐cell responses to allergen exposure in the same subjects before and after immunotherapy. In a double‐blind trial of grass pollen immunotherapy, nasal biopsies were obtained at baseline and during the peak pollen season following 2 years of immunotherapy. Placebo‐treated patients showed a seasonal increase in CD3+ T cells (P = 0·02) and in interleukin‐5 (IL‐5) mRNA+ cells (P = 0·03) and no change in interferon‐γ (IFN‐γ ) mRNA+ cells (P = 0·2) in the nasal mucosa. In contrast, in the immunotherapy‐treated group, there were no changes in the number of CD3+ T cells (P = 0·3) and IL‐5 mRNA+ cells (P = 0·2) but a significant increase in the number of IFN‐γ mRNA+ cells (P = 0·03). Furthermore, clinical improvement in the immunotherapy‐treated group was accompanied by a seasonal increase in the ratio of IFN‐γ to IL‐5 mRNA+ cells in the nasal mucosa (P = 0·03). In contrast, there were no significant changes in peripheral T‐cell proliferative responses or cytokine production for IFN‐γ or IL‐5 in response to grass pollen either within or between the two treatment groups. We conclude that successful grass pollen immunotherapy was associated with an increase in the ratio of IFN‐γ to IL‐5 mRNA+ cells in the nasal mucosa, whereas these changes were not reflected by alterations in peripheral blood T‐cell proliferative responses or cytokine production before/after treatment.

Local receptor revision and class switching to IgE in chronic rhinosinusitis with nasal polyps

Chronic rhinosinusitis with nasal polyps (NP) and allergic rhinitis (AR) is characterized by local Th2 inflammation and up‐regulation of IgE; however, IgE in NP is ‘polyclonal’ and allergen specific, whereas IgE in AR is ‘oligoclonal’ and allergen specific. Germinal center (GC) reactions occur in AR, while only the formation of GC‐like structures in NP is described. The aim of this study was to investigate the involvement of local IgE production, class switch recombination, and receptor revision in NP.

CCR4 in human allergen-induced late responses in the skin and lung

We studied the regulation of CCR4 expression in peripheral blood and in human models of cutaneous and pulmonary allergen challenge. CCR4 expression was detectable on freshly isolated CD4+ lymphocytes and in CD4+ and CD8+ T cell lines derived from blood of atopic donors. Numbers of CCR4+ cells were up‐regulated in T cell lines expanded in the presence of IL‐4. CCR4 mRNA was absent at baseline in normal subjects in lung and skin, but present at baseline in the lung of some atopics. Baseline expression of CCR4 mRNA and protein was higher in lung vs. skin, but allergen‐induced increases in CCR4 mRNA+ cells were observed in both organs. CCR4 protein+ cells were present at higher levels after allergen challenge in atopics compared to normal subjects. CCR4 may be important in the recruitment of T lymphocytes at sites of allergic inflammation, in a non‐organ‐specific manner.

Aberrant dendritic cell function conditions Th2-cell polarization in allergic rhinitis

Myeloid (m) and plasmacytoid (p) dendritic cells (DCs) regulate immune responses to allergens, whereas it remains unclear whether abnormal DC function characterizes patients with airway allergy and whether putative dysfunction exists only in target organs. To evaluate DC function from patients with allergic rhinitis (AR), we assessed nasal, cutaneous as well as blood DCs after in vivo and in vitro allergen challenge, respectively.