Aulikki Koskinen

Integrated Signals Between IL-13, IL-4, and IL-5 Regulate Airways Hyperreactivity

In this investigation, we have examined the integrated relationship between IL-13, IL-4, and IL-5 for the development of airways hyperreactivity (AHR) in a model of asthma in BALB/c mice. Sensitization and aeroallergen challenge of both wild-type (WT) and IL-13 gene-targeted (IL-13−/−) mice induced allergic disease that was characterized by pulmonary eosinophilia and AHR to β-methacholine. Although these responses in IL-13−/− mice were heightened compared with WT, they could be reduced to the level in nonallergic mice by the concomitant neutralization of IL-4. Mice in which both IL-4 and IL-13 were depleted displayed a marked reduction in tissue eosinophils, despite the development of a blood eosinophilia. Similar neutralization of IL-4 in WT mice only partially reduced AHR with no effect on tissue eosinophilia. In addition, neutralization of IL-5 in IL-13−/− mice, but not in WT mice, inhibited AHR, suggesting that tissue eosinophilia is linked to the mechanism underlying AHR only in the absence of IL-13. Additionally, mucus hypersecretion was attenuated in IL-13−/− mice, despite the persistence of AHR. Taken together, our data suggest both a modulatory role for IL-13 during sensitization and a proinflammatory role during aeroallergen challenge. The latter process appears redundant with respect to IL-4.

Intrinsic Defect in T Cell Production of Interleukin (IL)-13 in the Absence of Both IL-5 and Eotaxin Precludes the Development of Eosinophilia and Airways Hyperreactivity in Experimental Asthma

Interleukin (IL)-5 and IL-13 are thought to play key roles in the pathogenesis of asthma. Although both cytokines use eotaxin to regulate eosinophilia, IL-13 is thought to operate a separate pathway to IL-5 to induce airways hyperreactivity (AHR) in the allergic lung. However, identification of the key pathway(s) used by IL-5 and IL-13 in the disease process is confounded by the failure of anti–IL-5 or anti–IL-13 treatments to completely inhibit the accumulation of eosinophils in lung tissue. By using mice deficient in both IL-5 and eotaxin (IL-5/eotaxin−/−) we have abolished tissue eosinophilia and the induction of AHR in the allergic lung. Notably, in mice deficient in IL-5/eotaxin the ability of CD4+ T helper cell (Th)2 lymphocytes to produce IL-13, a critical regulator of airways smooth muscle constriction and obstruction, was significantly impaired. Moreover, the transfer of eosinophils to IL-5/eotaxin−/− mice overcame the intrinsic defect in T cell IL-13 production. Thus, factors produced by eosinophils may either directly or indirectly modulate the production of IL-13 during Th2 cell development. Our data show that IL-5 and eotaxin intrinsically modulate IL-13 production from Th2 cells and that these signaling systems are not necessarily independent effector pathways and may also be integrated to regulate aspects of allergic disease.

Role of interleukin‐13 in eosinophil accumulation and airway remodelling in a mouse model of chronic asthma

Background Interleukin‐13 is believed to be important in asthmatic inflammation and airway hyper‐reactivity.

Interleukin-5 and eosinophils induce airway damage and bronchial hyperreactivity during allergic airway inflammation in BALB/c mice.

The cytokines IL‐4 and lL‐5 secreted from antigen‐activated CD4+ T cells are thought to play central roles in the clinical expression and pathogenesis of asthma. However, there is conflicting evidence in animal models of allergic airway inflammation as to the relative importance of IL‐5 and eosinophils to the mechanisms underlying the induction of bronchial hyperreactivity and morphological changes to the airways in response to aeroallergen. In a recent investigation, the development of aeroallergen‐induced bronchial hyperreactivity in BALB/c mice was thought to be exclusively regulated by IL‐4, with no role for lL‐5 or eosinophils being demonstrated. In contrast, allergic airway disease could not be induced in IL‐5‐deficient mice of the C57BL/6 strain. A model of allergic airway inflammation, which displays certain phenotypic characteristics of late‐phase asthmatic responses, was used in the present investigation to establish a role for IL‐5 and eosinophils in the initiation of bronchial hyperreactivity and in the pathogenesis of allergic airway disease in BALB/c mice. Sensitization and repetitive aerosolization of mice with ovalbumin resulted in a severe airway inflammatory response which directly correlated with the induction of extensive airway damage and bronchial hyperreactivity to β‐methacholine. Treatment of mice with anti‐IL‐5 mAb before aeroallergen challenge, abolished blood and airway eosinophilia, lung damage and significantly reduced bronchial hyperreactivity. These results show that IL‐5 and eosinophilic inflammation play a substantial role in the pathophysiology of allergic airway disease and, moreover, that aeroallergen‐induced bronchial hyperreactivity is not exclusively regulated by IL‐4. These results also suggest that eosinophils are predominantly responsible for regulating aeroallergen‐induced structural changes to the airways which contribute, in part, to the mechanism underlying the induction of bronchial hyperreactivity. Thus, there are at least two distinct pathophysiological mechanisms for the induction of aeroallergen‐induced airway occlusion.

Increased Survival after Gemfibrozil Treatment of Severe Mouse Influenza

ABSTRACT Gemfibrozil, an agent that inhibits production of proinflammatory cytokines in addition to its clinically useful lipid-lowering activity, increased survival in BALB/c mice that were already ill from infection by influenza virus A/Japan/305/57 (H2N2). Gemfibrozil was administered intraperitoneally once daily from days 4 to 10 after intranasal exposure to the virus. Survival increased from 26% in vehicle-treated mice (n = 50) to 52% in mice given gemfibrozil at 60 mg/kg/day (n = 46) (P = 0.0026). If this principle translates to patients, a drug already approved for human use, albeit by a different route for another purpose, might be adapted relatively fast for use against influenza, conceivably including human infection with a derivative of the avian H5N1 strain.

Eosinophil degranulation in the allergic lung of mice primarily occurs in the airway lumen

Eosinophil degranulation is thought to play a pivotal role in the pathogenesis of allergic disorders. Although mouse models of allergic disorders have been used extensively to identify the contribution of eosinophils to disease, ultrastructural evidence of active granule disassembly has not been reported. In this investigation, we characterized the degree of eosinophil activation in the bone marrow, blood, lung tissue, and airways lumen [bronchoalveolar lavage fluid (BALF)] of ovalbumin‐sensitized and aero‐challenged wild‐type and interleukin‐5 transgenic mice. Degranulation was most prominent in and primarily compartmentalized to the airways lumen. Eosinophils released granule proteins by the process of piecemeal degranulation (PMD). Accordingly, recruitment and activation of eosinophils in the lung correlated with the detection of cell‐free eosinophil peroxidase in BALF and with the induction of airways hyper‐reactivity. As in previous studies with human eosinophils, degranulation of isolated mouse cells did not occur until after adherence to extracellular matrix. However, higher concentrations of exogenous stimuli appear to be required to trigger adherence and degranulation (piecemeal) of mouse eosinophils when compared with values reported for studies of human eosinophils. Thus, mouse eosinophils undergo PMD during allergic inflammation, and in turn, this process may contribute to pathogenesis. However, the degranulation process in the allergic lung of mice is primarily compartmentalized to the airway lumen. Understanding the mechanism of eosinophil degranulation in the airway lumen may provide important insights into how this process occurs in human respiratory diseases.

Cytotoxic T Cells Are the Predominant Players Providing Cross-Protective Immunity Induced by γ-Irradiated Influenza A Viruses

ABSTRACT We previously demonstrated that a single dose of nonadjuvanted intranasal γ-irradiated influenza A virus can provide robust protection in mice against both homologous and heterosubtypic challenges, including challenge with an H5N1 avian virus strain. We investigated the mechanism behind the observed cross-protection to define which arms of the adaptive immune response are involved in mediating this protection. Studies with gene knockout mice showed the cross-protective immunity to be mediated mainly by T cells and to be dependent on the cytolytic effector molecule perforin. Adoptive transfer of memory T cells from immunized mice, but not of memory B cells, protected naïve recipients against lethal heterosubtypic influenza virus challenge. Furthermore, γ-irradiated influenza viruses induced cross-reactive Tc-cell responses but not cross-neutralizing or cross-protective antibodies. In addition, histological analysis showed reduced lung inflammation in vaccinated mice compared to that in unvaccinated controls following heterosubtypic challenge. This reduced inflammation was associated with enhanced early recruitment of T cells, both CD4+ and CD8+, and with early influenza virus-specific cytotoxic T-cell responses. Therefore, cross-protective immunity induced by vaccination with γ-irradiated influenza A virus is mediated mainly by Tc-cell responses.

Residual active granzyme B in cathepsin C-null lymphocytes is sufficient for perforin-dependent target cell apoptosis.

Cathepsin C activates serine proteases expressed in hematopoietic cells by cleaving an N-terminal dipeptide from the proenzyme upon granule packaging. The lymphocytes of cathepsin C–null mice are therefore proposed to totally lack granzyme B activity and perforin-dependent cytotoxicity. Surprisingly, we show, using live cell microscopy and other methodologies, that cells targeted by allogenic CD8+ cytotoxic T lymphocyte (CTL) raised in cathepsin C–null mice die through perforin-dependent apoptosis indistinguishable from that induced by wild-type CTL. The cathepsin C–null CTL expressed reduced but still appreciable granzyme B activity, but minimal granzyme A activity. Also, in contrast to mice with inactivation of both their granzyme A/B genes, cathepsin C deficiency did not confer susceptibility to ectromelia virus infection in vivo. Overall, our results indicate that although cathepsin C clearly generates the majority of granzyme B activity, some is still generated in its absence, pointing to alternative mechanisms for granzyme B processing and activation. Cathepsin C deficiency also results in considerably milder immune deficiency than perforin or granzyme A/B deficiency.

Intranasal Flu Vaccine Protective against Seasonal and H5N1 Avian Influenza Infections

Background Influenza A (flu) virus causes significant morbidity and mortality worldwide, and current vaccines require annual updating to protect against the rapidly arising antigenic variations due to antigenic shift and drift. In fact, current subunit or split flu vaccines rely exclusively on antibody responses for protection and do not induce cytotoxic T (Tc) cell responses, which are broadly cross-reactive between virus strains. We have previously reported that γ-ray inactivated flu virus can induce cross-reactive Tc cell responses. Methodology/Principal Finding Here, we report that intranasal administration of purified γ-ray inactivated human influenza A virus preparations (γ-Flu) effectively induces heterotypic and cross-protective immunity. A single intranasal administration of γ-A/PR8[H1N1] protects mice against lethal H5N1 and other heterotypic infections. Conclusions/Significance Intranasal γ-Flu represents a unique approach for a cross-protective vaccine against both seasonal as well as possible future pandemic influenza A virus infections.

Residual active granzyme B in cathepsin C–null lymphocytes is sufficient for perforin-dependent target cell apoptosis

Sutton et al. 2007. J. Cell Biol. doi:10.1083/jcb.200609077 [OpenUrl][1][Abstract/FREE Full Text][2] [1]: {openurl}?query=rft_id%253Dinfo%253Adoi%252F10.1083%252Fjcb.200609077%26rft_id%253Dinfo%253Apmid%252F17283185%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%