Requirements for allergen-induced airway inflammation and hyperreactivity in CD4-deficient and CD4-sufficient HLA-DQ transgenic mice

HLA transgenic mice: application in reproducing idiosyncratic drug toxicity

Various types of transgenic mice carrying either class I or II human leukocyte antigen (HLA) molecules are readily available, and reports describing their use in a variety of studies have been published for more than 30 years. Examples of their use include the discovery of HLA-specific antigens against viral infection as well as the reproduction of HLA-mediated autoimmune diseases for the development of therapeutic strategies. Recently, HLA transgenic mice have been used to reproduce HLA-mediated idiosyncratic drug toxicity (IDT), a rare and unpredictable adverse drug reaction that can result in death. For example, abacavir-induced IDT has successfully been reproduced in HLA-B*57:01 transgenic mice. Several reports using HLA transgenic mice for IDT have proven the utility of this concept for the evaluation of IDT using various HLA allele combinations and drugs. It has become apparent that such models may be a valuable tool to investigate the mechanisms underlying HLA-mediated IDT. This review summarizes the latest findings in the area of HLA transgenic mouse models and discusses the current challenges that must be overcome to maximize the potential of this unique animal model.

Asthma translational medicine: report card

Over the last 30 years, scientific research into asthma has focused almost exclusively on one component of the disorder - airway inflammation - as being the key underlying feature. These studies have provided a remarkably detailed and comprehensive picture of the events following antigen challenge that lead to an influx of T cells and eosinophils in the airways. Indeed, in basic research, even the term "asthma" has become synonymous with a T helper 2 cell-mediated disorder. From this cascade of cellular activation processes and mediators that have been identified it has been possible to pinpoint critical junctures for therapeutic intervention, leading experimentalists to produce therapies that are very effective in decreasing airway inflammation in animal models. Many of these compounds have now completed early Phase 2 "proof-of-concept" clinical trials so the translational success of the basic research model can be evaluated. This commentary discusses clinical results from 39 compounds and biologics acting at 23 different targets, and while 6 of these drugs can be regarded as a qualified success, none benefit the bulk of asthma sufferers. Despite this disappointing rate of success, the same immune paradigm and basic research models, with a few embellishments to incorporate newly identified cells and mediators, continue to drive target identification and drug discovery efforts. It is time to re-evaluate the focus of these efforts.

Increased incidence of asthma in HIV-infected children treated with highly active antiretroviral therapy in the National Institutes of Health Women and Infants Transmission Study

BACKGROUND

Immunoreconstitution of HIV(+) patients after treatment with highly active antiretroviral therapy (HAART) appears to provoke inflammatory diseases.

OBJECTIVE

We sought to determine whether HIV(+) children receiving HAART (HIV(+) HAART(+)) have a higher incidence of asthma than HIV(+) children not receiving HAART (HIV(+) HAART(-)).

METHODS

Two thousand six hundred sixty-four children (193 HIV(+) and 2471 HIV(-) children) born to HIV(+) women were evaluated for the incidence and prevalence of asthma (ie, asthma medication use) and change of CD4(+) T-cell percentage with time.

RESULTS

The HIV(+) HAART(+) children had higher CD4(+) T-cell percentages, lower CD8(+) T-cell percentages, and lower viral burdens than the HIV(+) HAART(-) children (P < or = .05 to P < or = .01). The cumulative incidence of asthma medication use in HIV(+) HAART(+) children at 13.5 years increased to 33.5% versus 11.5% in HIV(+) HAART(-) children (hazard ratio, 3.34; P = .01) and was equal to that in the HIV(-) children. In children born before the HAART era, the prevalence of asthma medication use for HIV(+) HAART(+) children at 11 years of age was 10.4% versus 3.8% for HIV(+) HAART(-) children (odds ratio, 3.38; P = .02) and was equal to that of the HIV(-) children. The rate of change of CD4(+) T cells around the time of first asthma medication for HIV(+) HAART(+) versus HIV(+) HAART(-) children was 0.81%/y versus -1.43%/y (P = .01).

CONCLUSION

The increased incidence of asthma in HIV(+) HAART(+) children might be driven by immunoreconstitution of CD4(+) T cells.

Insights into the pathogenesis of asthma utilizing murine models

Asthma is a common syndrome in children and adults. Despite the increasing prevalence and socioeconomic burden, the underlying pathophysiology remains poorly defined in a large percentage of asthmatics. Animal models and, in particular, murine models of allergic airway disease have helped to reveal some of the potential underlying mechanisms and have played an important role in identifying the importance of T cells and TH2 cytokines in development of allergen-induced inflammation and airway hyperresponsiveness. In addition, other cell types including mast cells and eosinophils have been implicated in the development of some aspects of the disease. To further understand this complex syndrome, the development of animal models which mimic elements of this chronic airway disease is essential.

CD28 costimulation is critical for experimental allergic asthma in HLA-DQ8 transgenic mice

The objective of this study was to investigate the contribution of the CD28 costimulatory molecules to allergen-induced primary and chronic inflammatory responses. To this end, we have developed and characterized a short ragweed allergen-induced asthma model involving sensitization of HLA-DQ transgenic mice followed by intranasal challenge with allergen. Forty-eight hours after primary challenge, sensitized DQ8 mice developed pulmonary eosinophilic inflammation, airway hyperreactivity, Th2 cytokines, and IgE/IgG1 Ab. This allergic inflammatory response was absent in H-2Abeta(0) and DQ8/CD28(0) mice. Secondary rechallenge with allergen 4 weeks later induced even greater inflammatory changes in the airways of DQ8 mice with eosinophils being the predominant inflammatory cells while only pulmonary lymphocytosis was observed in DQ8/CD28(0) mice. No inflammation was detected in H-2Abeta(0) mice. Proliferation and cytokine profile studies demonstrated that CD28 regulates T-cell activation and effector function. Therefore, CD28 is essential for the extrinsic asthma and can be a target for immunotherapy.