Search

Aeroallergens are the most common triggers for the development of asthma. Recent birth cohort studies have identified viral infections occurring against a background of aeroallergen sensitization as a potent risk factor for initiation of asthma. Viral infection enhances immunopathogenic potential of pre-existing inhalant allergy via modulating airway mucosal dendritic cells. By using an allergen inhalation challenge clinical model, studies have shown that the late asthma response (LAR) is associated with more pronounced allergen-induced airway inflammation and airway hyperresponsiveness. The degree of airway eosinophilia, regulated by bone marrow progenitor cells and interleukin-5 level, correlates with the magnitude of the LAR and the increase in hyperresponsiveness. Both myeloid and plasmacytoid dendritic cell subsets have been involved in the pathogenesis of allergen-induced LAR. Myeloid dendritic cells are responsible for the allergen presentation and induction of inflammation and plasmacytoid dendritic cells play a role in the resolution of allergen-induced inflammation. A variety of potential new classes of asthma medication has also been evaluated with the allergen inhalation challenge in mild asthmatic subjects. Examples are TPI ASM8, an inhaled anti-sense oligonucleotide drug product, which attenuated both early and LARs via inhibition of the target gene mRNA of chemokine receptor 3, and the common β chain of interleukin-3, interleukin-5 and granulocyte-macrophage colony-stimulating factor receptor. Anti-human antibody interleukin-13 (IM-638) significantly attenuated both early and late allergen-induced asthma response. Pitrakinra, which targets both interleukin-4 and interleukin-13, substantially diminishes allergen-induced airway responses. Allergen-induced airway responses are a valuable way to evaluate the activity of possible new therapies in asthmatic airways.

Background: TPI ASM8 contains two modified phosphorothioate antisense oligonucleotides (AON), one targeting the common beta chain (βc) of the IL-3/IL-5/GM-CSF receptors and the other targeting the chemokine receptor CCR3. Inhalation of TPI ASM8 significantly improves lung function and sputum eosinophilia after allergen inhalation challenge in asthmatics., Objective: This study assessed whether TPI ASM8 reduces airway levels of haemopoietic progenitor cells., Methods: This open-label study was conducted in 14 stable, allergic mild asthmatic subjects with early- and late-phase allergen-induced bronchoconstriction. Subjects underwent allergen challenges after 4-day treatment with placebo, 4 mg b.i.d. and 8 mg o.d. of TPI ASM8. Sputum was induced before, 7 and 24 h after allergen challenges for progenitor measurements. Treatments were separated by 2-3 weeks., Results: TPI ASM8 reduced allergen-induced sputum eosinophils, and the early and late asthmatic responses (P<0.05). TPI ASM8 also reduced the number of CD34(+) CCR3(+) cells (P=0.004) and CD34(+) IL-5Rα(+) cells (P=0.016), and the proportion of CD34(+) cells expressing IL-5Rα (P=0.036)., Conclusions and Clinical Relevance: TPI ASM8 was safe and well tolerated. The results of this study demonstrate blocking of CCR3 and βc expression by TPI ASM8 significantly inhibits the accumulation of eosinophils and eosinophil progenitors in the airways after allergen challenge. Inhibition of airway progenitor cell accumulation presents a novel therapeutic target., (© 2011 Blackwell Publishing Ltd.)

Background: TPI ASM8 contains two modified antisense oligonucleotides (AON) targeting the beta subunit (β(c) ) of the IL-3, IL-5, GM-CSF receptors and the chemokine receptor CCR3. A previous study suggested that TPI ASM8 had broader effects than just inhibition of eosinophils in asthmatics., Objective: We assessed whether TPI ASM8 caused a dose-dependent attenuation in the inflammatory and physiological changes after inhaled allergen challenge (AIC)., Methods: This single-center, open-label, stepwise-ascending dose study was conducted in fourteen stable, mild allergic asthmatics. Following placebo AIC, subjects underwent AIC after 4 days treatment with 1, 2, and 4 mg BID and finally 8 mg once daily (OD) of TPI ASM8, inhaled via the I-Neb™ nebuliser. Treatments were separated by 2-3-week washout periods., Results: TPI ASM8 was safe and well tolerated at all doses. TPI ASM8 8 mg OD reduced eosinophils in sputum after AIC (by 60.9% at 7 h and 68.4% at 24 h post-AIC, P=0.016 and P=0.007, respectively). Additionally, TPI ASM8 8 mg OD significantly attenuated the early and late airway responses as shown by the reduction in the area under the curve by 45% (P=0.016) and 59%, (P=0.0015), respectively, the increase in eosinophil cationic protein (ECP) by up to 57% (P=0.021), and airway responsiveness to methacholine by more than 1 doubling dose (P=0.012). A dose-response relationship was noted, and efficacy was maintained with once per day administration., Conclusions: TPI ASM8 attenuated a broad range of inflammatory and physiological changes after AIC, suggesting that CCR3, IL-3, and GM-CSF also are important targets for the management of asthma., (© 2011 John Wiley & Sons A/S.)

Background: We have previously shown that short-course treatment with Amb a 1-immunostimulatory phosphorothioate oligonucleotide conjugate (AIC) before the ragweed season modifies the response of the nasal mucosa to allergen challenge in ragweed-sensitive patients by increasing Th1 cytokines and decreasing both Th2 cytokines and eosinophilia after the ragweed season. The effect of AIC immunotherapy on CD4+CD25+ T cell expression in the nasal mucosa is unknown., Objective: To determine the in vivo effect of short-course AIC immunotherapy on CD4+CD25+ regulatory T cells in the nasal mucosa of ragweed-sensitive subjects., Methods: 19 ragweed-sensitive patients with allergic rhinitis were randomly assigned to receive either 6 escalating doses of AIC (0.06-12microg; n = 12) or placebo (n = 7) at weekly intervals immediately before the 2001 ragweed season. Nasal biopsies were taken at baseline prior to immunization and again post immunization 24 hours after ragweed allergen challenge at the start and end of the ragweed season. The expression of T regulatory cells, IL-10 and TGF-beta was assessed at each time point by immunohistochemistry., Results: The numbers of allergen-induced CD4+-, CD4+CD25+-, IL-10- and TGF-beta-positive cells in the nasal mucosa after AIC immunization before the ragweed season did not differ between the two groups. Repeat challenge after the ragweed season led to a significant increase in CD4+CD25+ cells in AIC-compared with placebo-treated subjects. A trend toward an increase in IL-10-positive cells in the AIC-treated group did not reach statistical significance., Conclusions: Short-course AIC immunotherapy increases CD4+CD25+ regulatory T cell infiltration in the nasal mucosa following allergen challenge after seasonal ragweed-pollen exposure.

Rationale: The drug product TPI ASM8 contains two modified phosphorothioate antisense oligonucleotides designed to inhibit allergic inflammation by down-regulating human CCR3 and the common beta chain (beta(c)) of IL-3, IL-5, and granulocyte-macrophage colony-stimulating factor receptors., Objectives: This study examined the effects of inhaled TPI ASM8 on sputum cellular influx, CCR3 and beta(c) mRNA and protein levels, and the airway physiologic response after inhaled allergen., Methods: Seventeen subjects with mild atopic asthma were randomized in a crossover study to inhale 1,500 microg TPI ASM8 or placebo by nebulizer, once daily for 4 days. On Day 3, subjects underwent allergen inhalation challenge. Sputum samples were collected before and after allergen. CCR3 and beta(c) protein levels were measured by flow cytometry, mRNA was measured using real-time quantitative polymerase chain reaction, and the FEV1 was measured over 7 hours after challenge., Measurements and Main Results: Compared with placebo, TPI ASM8 inhibited sputum eosinophil influx by 46% (P = 0.02) and blunted the increase in total cells (63%) after allergen challenge. TPI ASM8 significantly reduced the early asthmatic response (P = 0.04) with a trend for the late asthmatic response (P = 0.08). The allergen-induced (Day 2 to Day 3) levels of beta(c) mRNA and CCR3 mRNA in sputum-derived cells were inhibited by TPI ASM8 (P = 0.039 and P = 0.054, respectively), with no significant effects on the cell surface protein expression of CCR3 and beta(c) (P > 0.05). No serious adverse events were reported., Conclusions: TPI ASM8 attenuates the allergen-induced increase in target gene mRNA and airway responses in subjects with mild asthma. Clinical trial registered with www.clinicaltrials.gov (NCT 00264966).