Short ragweed allergen induces eosinophilic lung disease in HLA-DQ transgenic mice

Plexin B1 controls Treg numbers, limits allergic airway inflammation, and regulates mucins

We investigated the effect of global Plexin B1 deficiency on allergic airway responses to house dust mite (HDM) or ovalbumin (OVA). In the HDM model, there were higher Th2 cytokine levels in the BALF of Plexin B1 knock-out (KO) mice compared to wild type (WT), and tissue inflammation and mucus production were modestly enhanced. In the OVA model, Plexin B1 deficiency led to increases in lung inflammation, mucus production, and lung Th2 cytokines accompanied by dysregulated mucin gene expression without affecting anti-OVA IgE/IgG1 levels. Spleen cells from Plexin B1 KO mice proliferated more robustly than WT cells in vitro to a variety of stimuli. Plexin B1 KO CD4+ T cells from spleens expressed higher levels of Ki-67 and CD69 compared to WT cells. Spleen cells from naïve Plexin B1 KO mice secreted increased amounts of IL-4 and IL-6 when pulsed in vitro with OVA whereas in vivo OVA-primed spleen cells produced IL-4/IL-5 when subjected to in vitro OVA restimulation. The upregulated allergic inflammatory response in Plexin B1 KO mice was associated with a lower number of Tregs in the lung tissues. Moreover, these mice displayed lower numbers of Treg cells in the lymphoid tissues at the baseline. These results demonstrate a previously unrecognized link between Plexin B1, Treg cells, and mucus in allergic lung inflammation.

Aerofloral studies and allergenicity of dominant pollen types in Taraba and Bauchi States of Northeastern Nigeria

Pollen and spores have been identified as major airborne bio-particles inducing respiratory disorders including allergic rhinitis and atopic dermatitis among hypersensitive individuals. The present study was conducted with a view to investigating monthly depositional rate of atmospheric palynomorphs to determine the influence of the immediate vegetation on airborne pollen distribution; allergenic activities of dominant atmospheric pollen types at selected study locations in Taraba and Bauchi States, Northeastern Nigeria. Bioaerosols were collected using Tauber-like pollen traps and subjected to standard palynological treatment procedures, microscopy and photomicrography. Plant enumeration within the surrounding vegetation revealed that some airborne pollen types were produced by local plants at the study locations. Spores of Nephrolepis sp., Pteris sp. and a trilete fern, as well as diatoms were also recovered. Crude protein contents of some dominant pollen types; Borreria verticillata (L.) G.F.W. Meyer and Panicum maximum Jacq. for Taraba State; Leucaena leucocephala (Lam.) de Wit. and Terminalia catappa L. for Bauchi State, were quantified and extracted to sensitize Mus musculus mice for serology (ELISA) and haematology (differential and total white blood cell counts). Statistical significance was tested and recorded in the correlation between levels of serological and haematological parameters elicited by each test group; differences between levels of these parameters elicited by each test group and those of the control, as well as at varying sensitization periods. In the Leucaena leucocephala test group, swollen body and histopathological morbid features showing more extensive areas of inflammatory cells and alveoli filled with fluid in the lungs, were recorded in two dead M. musculus, respectively. The study revealed that all the tested pollen types are possible allergens at the study locations, establishing a complexity of interaction among allergy mediators at varied periods of mice sensitization and forming a paradigm of human immune response to the different pollen allergens.

Signaling via dopamine and adenosine receptors modulate viral peptide-specific and T-cell IL-8 response in COVID-19

B-cell but not T-cell responses have been extensively studied using peripheral blood mononuclear cells (PBMCs) obtained from patients with coronavirus disease 2019 (COVID-19). Our recent study showed that not only T-helper (Th) 17 but also Th1 cells directly produce interleukin (IL)-8, a major source of neutrophilic inflammation, which is also known to induce disseminated intravascular coagulation (DIC) in COVID-19 patients. Neutrophilic inflammation caused by IL-17A or IL-8 can be fatal; thus, therapeutic intervention is highly expected. The present study aimed to investigate the T-cell responses in the Japanese patients. We synthesized spike protein-derived 15-mer peptides that are expected to bind to HLA class II allelic products frequently observed in the Japanese population, and checked the T-cell responses in Japanese patients with COVID-19. We have found that (i) patients show marked IL-8 but not IL-17A responses; (ii) these responses are restricted by HLA-DR; and (iii) IL-8 responses are abrogated by a dopamine D2 like receptor (D2R) agonist, ropinirole, and an adenosine A2a receptor (A2aR) antagonist, istradefylline. Compounds used for the treatment of Parkinson's disease may ease DIC in COVID-19. (183 words).

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.

Are We Meeting the Promise of Endotypes and Precision Medicine in Asthma?

While the term asthma has long been known to describe heterogeneous groupings of patients, only recently have data evolved which enable a molecular understanding of the clinical differences. The evolution of transcriptomics (and other 'omics platforms) and improved statistical analyses in combination with large clinical cohorts opened the door for molecular characterization of pathobiologic processes associated with a range of asthma patients. When linked with data from animal models and clinical trials of targeted biologic therapies, emerging distinctions arose between patients with and without elevations in type 2 immune and inflammatory pathways, leading to the confirmation of a broad categorization of type 2-Hi asthma. Differences in the ratios, sources, and location of type 2 cytokines and their relation to additional immune pathway activation appear to distinguish several different (sub)molecular phenotypes, and perhaps endotypes of type 2-Hi asthma, which respond differently to broad and targeted anti-inflammatory therapies. Asthma in the absence of type 2 inflammation is much less well defined, without clear biomarkers, but is generally linked with poor responses to corticosteroids. Integration of "big data" from large cohorts, over time, using machine learning approaches, combined with validation and iterative learning in animal (and human) model systems is needed to identify the biomarkers and tightly defined molecular phenotypes/endotypes required to fulfill the promise of precision medicine.

The genetic and epigenetic landscapes of the epithelium in asthma

Asthma is a global health problem with increasing prevalence. The airway epithelium is the initial barrier against inhaled noxious agents or aeroallergens. In asthma, the airway epithelium suffers from structural and functional abnormalities and as such, is more susceptible to normally innocuous environmental stimuli. The epithelial structural and functional impairments are now recognised as a significant contributing factor to asthma pathogenesis. Both genetic and environmental risk factors play important roles in the development of asthma with an increasing number of genes associated with asthma susceptibility being expressed in airway epithelium. Epigenetic factors that regulate airway epithelial structure and function are also an attractive area for assessment of susceptibility to asthma. In this review we provide a comprehensive discussion on genetic factors; from using linkage designs and candidate gene association studies to genome-wide association studies and whole genome sequencing, and epigenetic factors; DNA methylation, histone modifications, and non-coding RNAs (especially microRNAs), in airway epithelial cells that are functionally associated with asthma pathogenesis. Our aims were to introduce potential predictors or therapeutic targets for asthma in airway epithelium. Overall, we found very small overlap in asthma susceptibility genes identified with different technologies. Some potential biomarkers are IRAKM, PCDH1, ORMDL3/GSDMB, IL-33, CDHR3 and CST1 in airway epithelial cells. Recent studies on epigenetic regulatory factors have further provided novel insights to the field, particularly their effect on regulation of some of the asthma susceptibility genes (e.g. methylation of ADAM33). Among the epigenetic regulatory mechanisms, microRNA networks have been shown to regulate a major portion of post-transcriptional gene regulation. Particularly, miR-19a may have some therapeutic potential.

Generating Transgenic Mouse Models for Studying Celiac Disease

This chapter provides a brief overview of current animal models for studying celiac disease, with a focus on generating HLA transgenic mouse models. Human Leukocyte Antigen class II molecules have been a particular target for transgenic mice due to their tight association with celiac disease, and a number of murine models have been developed which had the endogenous MHC class II genes replaced with insertions of disease susceptible HLA class II alleles DQ2 or DQ8. Additionally, transgenic mice that overexpress interleukin-15 (IL-15), a key player in the inflammatory cascade that leads to celiac disease, have also been generated to model a state of chronic inflammation. To explore the contribution of specific bacteria in gluten-sensitive enteropathy, the nude mouse and rat models have been studied in germ-free facilities. These reductionist mouse models allow us to address single factors thought to have crucial roles in celiac disease. No single model has incorporated all of the multiple factors that make up celiac disease. Rather, these mouse models can allow the functional interrogation of specific components of the many stages of, and contributions to, the pathogenic mechanisms that will lead to gluten-dependent enteropathy. Overall, the tools for animal studies in celiac disease are many and varied, and provide ample space for further creativity as well as to characterize the complete and complex pathogenesis of celiac disease.

Cysteine peptidases as schistosomiasis vaccines with inbuilt adjuvanticity

Schistosomiasis is caused by several worm species of the genus Schistosoma and afflicts up to 600 million people in 74 tropical and sub-tropical countries in the developing world. Present disease control depends on treatment with the only available drug praziquantel. No vaccine exists despite the intense search for molecular candidates and adjuvant formulations over the last three decades. Cysteine peptidases such as papain and Der p 1 are well known environmental allergens that sensitize the immune system driving potent Th2-responses. Recently, we showed that the administration of active papain to mice induced significant protection (P<0.02, 50%) against an experimental challenge infection with Schistosoma mansoni. Since schistosomes express and secrete papain-like cysteine peptidases we reasoned that these could be employed as vaccines with inbuilt adjuvanticity to protect against these parasites. Here we demonstrate that sub-cutaneous injection of functionally active S. mansoni cathepsin B1 (SmCB1), or a cathepsin L from a related parasite Fasciola hepatica (FhCL1), elicits highly significant (P<0.0001) protection (up to 73%) against an experimental challenge worm infection. Protection and reduction in worm egg burden were further increased (up to 83%) when the cysteine peptidases were combined with other S. mansoni vaccine candidates, glyceraldehyde 3-phosphate dehydrogenase (SG3PDH) and peroxiredoxin (PRX-MAP), without the need to add chemical adjuvants. These studies demonstrate the capacity of helminth cysteine peptidases to behave simultaneously as immunogens and adjuvants, and offer an innovative approach towards developing schistosomiasis vaccines

Neuroimmune semaphorin 4A as a drug and drug target for asthma

Neuroimmune semaphorin 4A (Sema4A) has been shown to play an important costimulatory role in T cell activation and regulation of Th1-mediated diseases such as multiple sclerosis (MS), experimental autoimmune encephalomyelitis (EAE), and experimental autoimmune myocarditis (EAM). Sema4A has three functional receptors, Tim-2 expressed on CD4+ T cells, Th2 cells in particular, and Plexin B1 and D1 predominantly expressed on epithelial and endothelial cells, correspondingly. We recently showed that Sema4A has a complex expression pattern in lung tissue in a mouse model of asthma. We and others have shown that corresponding Plexin expression can be found on immune cells as well. Moreover, we demonstrated that Sema4A-deficient mice displayed significantly higher lung local and systemic allergic responses pointing to its critical regulatory role in the disease. To determine the utility of Sema4A as a novel immunotherapeutic, we introduced recombinant Sema4A protein to the allergen-sensitized WT and Sema4A(-/-) mice before allergen challenge. We observed significant reductions in the allergic inflammatory lung response in Sema4A-treated mice as judged by tissue inflammation including eosinophilia and mucus production. Furthermore, we demonstrated that in vivo administration of anti-Tim2 Ab led to a substantial upregulation of allergic inflammation in WT mouse lungs. These data highlight the potential to develop Sema4A as a new therapeutic for allergic airway disease.

IL-13 and STAT6 signaling involve in low dose lipopolysaccharide induced murine model of asthma

Background

We reported that level of lipopolysaccharide (LPS) exposure determined the type of airway inflammation in a murine model of asthma.

Objective

The purpose of this study is to evaluated the role of IL-13 in low dose LPS induced murine model of asthma using IL-13 and signal transducer and activator of transcription 6 (STAT6) deficient mice.

Methods

Mice were sensitized with an intranasal application of LPS-depleted ovalbumin (OA) and different doses of LPS (0.1 and 10 µg), and then challenged intranasally with OA alone. The phenotype changes between wild type (WT) and IL-13^-/- mice and between WT and STAT6^-/- mice were evaluated.

Results

We confirmed again that low and high dose LPS resulted in different phenotypes of murine asthma. In the present study, we observed that phenotypes of murine asthma induced by low dose LPS were abolished in the homozygous null mutation of the IL-13 and STAT6 gene. However, those changes were not shown in mice sensitized OA plus high dose LPS.

Conclusion

IL-13 plays an important role in low dose LPS induced murine model of asthma. Our results provided a new insight in understanding of the potential role of IL-13 in innate immunity in human allergic asthma.

STAT6 controls the number of regulatory T cells in vivo, thereby regulating allergic lung inflammation

STAT6 plays a central role in IL-4-mediated allergic responses. Several studies indicate that regulatory T cells (Tregs) can be modulated by IL-4 in vitro. We previously showed that STAT6(-/-) mice are highly resistant to allergic lung inflammation even when wild-type Th2 effectors were provided and that they have increased numbers of Tregs. However, the role of STAT6 in modulating Tregs in vivo during allergic lung inflammation has not been thoroughly investigated. To examine Treg and STAT6 interaction during allergic inflammation, STAT6(-/-), STAT6xRAG2(-/-), and RAG2(-/-) mice were subjected to OVA sensitization and challenge following adoptive transfer of OVA-specific, wild-type Th2 effectors with or without prior Treg depletion/inactivation, using anti-CD25 (PC61). As expected, STAT6(-/-) mice were highly resistant to airway inflammation and remodeling. In contrast, allergic lung inflammation was partially restored in STAT6(-/-) mice treated with PC61 to levels observed in STAT6xRAG2(-/-) mice. In some cases, STAT6xRAG2(-/-) mice were also given natural Tregs along with Th2 effectors. Adoptive transfer of natural Tregs caused a substantial reduction in bronchoalveolar lavage eosinophil composition and suppressed airway remodeling and T cell migration into the lung in STAT6xRAG2(-/-) mice to levels comparable to those in STAT6(-/-) mice. These results demonstrate the STAT6-dependent suppression of Tregs in vivo to promote allergic airway inflammation.

STAT4-dependent and -independent Th2 responses correlate with protective immunity against lung infection with Pneumocystis murina

Although it is clear that the loss of CD4(+) T cells is a predisposing factor for the development of Pneumocystis pneumonia, specific Th mechanisms mediating protection are not well understood. Th1, Th2, and Th17 responses have each been implicated in protective responses during infection. As STAT4 may promote Th1 and Th17 development, yet antagonize Th2 development, we investigated its role in Pneumocystis murina host defense. STAT4 was required for Th1 and, unexpectedly, Th2 responses in the lungs of C57BL/6 (BL/6) and BALB/c mice 14 d postchallenge, but only BALB/c Stat4(-/-) mice demonstrated susceptibility to P. murina lung infection. BL/6 Stat4(-/-), but not BALB/c Stat4(-/-), mice maintained an enhanced alternatively activated (M2) macrophage signature in the lungs, which we have previously reported to be associated with enhanced P. murina clearance. In addition, anti-P. murina class-switched Abs were increased in BL/6 Stat4(-/-) mice, but not BALB/c Stat4(-/-) mice. Supporting our experimental observations, plasma from HIV-infected individuals colonized with Pneumocystis jirovecii contained significantly lower levels of the Th2 cytokines IL-4, IL-5, and IL-13 compared with HIV-infected individuals who were not colonized. Collectively, our data suggest that robust local and systemic Th2-mediated responses are critical for immunity to Pneumocystis.

A comparison of antiasthma drugs between acute and chronic ovalbumin-challenged guinea-pig models of asthma

Pre-clinical evaluation of asthma therapies requires animal models of chronic airways inflammation, airway hyperresponsiveness (AHR) and lung remodelling that accurately predict drug effectiveness in human asthma. However, most animal models focus on acute allergen challenges where chronic inflammation and airway remodelling are absent. Chronic allergen challenge models have been developed in mice but few studies use guinea-pigs which may be more relevant to humans. We tested the hypothesis that a chronic rather than acute pulmonary inflammation model would best predict clinical outcome for asthma treatments. Guinea-pigs sensitized with ovalbumin (OVA) received single (acute) or nine OVA inhalation challenges at 48 h intervals (chronic). Airways function was recorded as specific airways conductance (sG(aw)) in conscious animals for 12 h after OVA challenge. AHR to inhaled histamine, inflammatory cell influx and lung histology were determined 24 h after the single or 9th OVA exposure. The inhaled corticosteroid, fluticasone propionate (FP), the phosphodiesterase 4 inhibitor, roflumilast, and the inducible nitric oxide synthase (iNOS) inhibitor, GW274150, orally, were administered 24 and 0.5 h before and 6 h after the single or final chronic OVA exposure. Both models displayed early (EAR) and late (LAR) asthmatic responses to OVA challenge, as falls in sG(aw), AHR, as increased histamine-induced bronchoconstriction, and inflammatory cell influx. Tissue remodelling, seen as increased collagen and goblet cell hyperplasia, occurred after multiple OVA challenge. Treatment with FP and roflumilast inhibited the LAR, cell influx and AHR in both models, and the remodelling in the chronic model. GW274150 also inhibited the LAR, AHR and eosinophil influx in the acute model, but not, together with the remodelling, in the chronic model. In the clinical setting, inhaled corticosteroids and phosphodiesterase 4 inhibitors are relatively effective against most features of asthma whereas the iNOS inhibitor GW274150 was ineffective. Thus, while there remain certain differences between our data and clinical effectiveness of these antiasthma drugs, a chronic pulmonary inflammation guinea-pig model does appear to be a better pre-clinical predictor of potential asthma therapeutics than an acute model.

Neuroimmune semaphorin 4A downregulates the severity of allergic response

To define the role of semaphorin 4A (Sema4A) in allergic response, we employed Sema4A⁻/⁻ and wild-type (WT) mice in the experimental model of ovalbumin (OVA)-induced allergic airway inflammation. We observed a selective increase in eosinophilic airway infiltration accompanied by bronchial epithelial cell hyperplasia in allergen-treated Sema4A⁻/⁻ mice relative to WT mice. This enhanced inflammatory response was associated with a selective increase in bronchoalveolar lavage (BAL) interleukin 13 (IL-13) content, augmented airway hyperreactivity, and lower regulatory T cell (Treg) numbers. In vivo allergen-primed Sema4A⁻/⁻ CD4+ T cells were more effective in transferring T helper type 2 (Th2) response to naive mice as compared with WT CD4+ T cells. T-cell proliferation and IL-13 productions in OVA₃₂₃₋₃₃₉-restimulated Sema4A⁻/⁻ cell cultures were upregulated. Generated bone marrow chimeras showed an equal importance of both lung-resident cell and inflammatory cell Sema4A expression in optimal disease regulation. These data provide a new insight into Sema4A biology and define Sema4A as an important regulator of Th2-driven lung pathophysiology.

Visualization of murine intranasal dosing efficiency using luminescent Francisella tularensis: effect of instillation volume and form of anesthesia

Intranasal instillation is a widely used procedure for pneumonic delivery of drugs, vaccine candidates, or infectious agents into the respiratory tract of research mice. However, there is a paucity of published literature describing the efficiency of this delivery technique. In this report we have used the murine model of tularemia, with Francisella tularensis live vaccine strain (FTLVS) infection, to evaluate the efficiency of pneumonic delivery via intranasal dosing performed either with differing instillation volumes or different types of anesthesia. FTLVS was rendered luminescent via transformation with a reporter plasmid that constitutively expressed the Photorhabdus luminescens lux operon from a Francisella promoter. We then used an IVIS Spectrum whole animal imaging system to visualize FT dissemination at various time points following intranasal instillation. We found that instillation of FT in a dose volume of 10 µl routinely resulted in infection of the upper airways but failed to initiate infection of the pulmonary compartment. Efficient delivery of FT into the lungs via intranasal instillation required a dose volume of 50 µl or more. These studies also demonstrated that intranasal instillation was significantly more efficient for pneumonic delivery of FTLVS in mice that had been anesthetized with inhaled (isoflurane) vs. parenteral (ketamine/xylazine) anesthesia. The collective results underscore the need for researchers to consider both the dose volume and the anesthesia type when either performing pneumonic delivery via intranasal instillation, or when comparing studies that employed this technique.

WITHDRAWN: A brief autobiography

The Publisher regrets that this article is an accidental duplication of an article that has already been published, doi:10.1016/j.jaut.2011.05.017 The duplicate article has therefore been withdrawn.

Chella David: a lifetime contribution in translational immunology

Immunology, like most scientific disciplines, is filled with buzz words. One such buzz word or term has been coined "translational immunology". Indeed, translational research is amongst the most popular expressions used to justify the use of basic research in the hopes that such research will lead to solutions to clinical problems. In fact, no such justification is needed and some of the most important observations in clinical medicine have been derived from basic science; basic science that had no idea at its time of its usefulness in clinical medicine. This special issue is devoted to Chella David. Chella's contributions in immunology have been legion. Before inbred mice became popular, long before multi-million dollar companies were developed to develop such models, Chella David was hard at the bench studying the genetics of the murine immune system and the importance of such mouse models in autoimmune diseases. Importantly, Dr. David provided animals without strings, without the burdens of MTAs, that now impede research. Chella has been generous with his time, with his reagents, and has been a caring and devoted mentor to generations of students. This issue is part of our series to recognize autoimmunologists and dedicated themes that include papers in multiple disciplines of immunology, but especially are focused on cutting-edge applications that will improve clinical therapeutics. Chella David, at age 75, is an athlete in immunology and still keeps going with the same enthusiasm as manifest as a young post-doc.

Expression of neuroimmune semaphorins 4A and 4D and their receptors in the lung is enhanced by allergen and vascular endothelial growth factor

Background

Semaphorins were originally identified as molecules regulating a functional activity of axons in the nervous system. Sema4A and Sema4D were the first semaphorins found to be expressed on immune cells and were termed "immune semaphorins". It is known that Sema4A and Sema4D bind Tim-2 and CD72 expressed on leukocytes and PlexinD1 and B1 present on non-immune cells. These neuroimmune semaphorins and their receptors have been shown to play critical roles in many physiological and pathological processes including neuronal development, immune response regulation, cancer, autoimmune, cardiovascular, renal, and infectious diseases. However, the expression and regulation of Sema4A, Sema4D, and their receptors in normal and allergic lungs is undefined.

Results

Allergen treatment and lung-specific vascular endothelial growth factor (VEGF) expression induced asthma-like pathologies in the murine lungs. These experimental models of allergic airway inflammation were used for the expression analysis of immune semaphorins and their receptors employing immunohistochemistry and flow cytometry techniques. We found that besides accessory-like cells, Sema4A was also detected on bronchial epithelial and smooth muscle cells, whereas Sema4D expression was high on immune cells such as T and B lymphocytes. Surprisingly, under inflammation various cell types including macrophages, lymphocytes, and granulocytes in the lung expressed Tim-2, a previously defined marker for Th2 cells. CD72 was found on lung immune, inflammatory, and epithelial cells. Bronchial epithelial cells were positive for both plexins, whereas some endothelial cells selectively expressed Plexin D1. Plexin B1 expression was also detected on lung DC. Both allergen and VEGF upregulated the expression of neuroimmune semaphorins and their receptors in the lung tissue. However, the lung tissue Sema4A-Tim2 expression was rather weak, whereas Sema4D-CD72 ligand-receptor pair was vastly upregulated by allergen. Soluble Sema4D protein was present in the lung lysates and a whole Sema4A protein plus its dimer were readily detected in the bronchoalveolar (BAL) fluids under inflammation.

Conclusions

This study clearly shows that neuroimmune semaphorins Sema4A and Sema4D and their receptors might serve as potential markers for the allergic airway inflammatory diseases. Our current findings pave the way for further investigations of the role of immune semaphorins in inflammation and their use as potential therapeutic targets for the inflammatory lung conditions.

STAT6 expression in multiple cell types mediates the cooperative development of allergic airway disease

Th2 cells induce asthma through the secretion of cytokines. Two such cytokines, IL-4 and IL-13, are critical mediators of many features of this disease. They both share a common receptor subunit, IL-4Rα, and signal through the STAT6 pathway. STAT6(-/-) mice have impaired Th2 differentiation and reduced airway response to allergen. Transferred Th2 cells were not able to elicit eosinophilia in response to OVA in STAT6(-/-) mice. To clarify the role of STAT6 in allergic airway inflammation, we generated mouse bone marrow (BM) chimeras. We observed little to no eosinophilia in OVA-treated STAT6(-/-) mice even when STAT6(+/+) BM or Th2 cells were provided. However, when Th2 cells were transferred to STAT6×Rag2(-/-) mice, we observed an eosinophilic response to OVA. Nevertheless, the expression of STAT6 on either BM-derived cells or lung resident cells enhanced the severity of OVA-induced eosinophilia. Moreover, when both the BM donor and recipient lacked lymphocytes, transferred Th2 cells were sufficient to induce the level of eosinophilia comparable with that of wild-type (WT) mice. The expression of STAT6 in BM-derived cells was more critical for the enhanced eosinophilic response. Furthermore, we found a significantly higher number of CD4(+)CD25(+)Foxp3(+) T cells (regulatory T cells [Tregs]) in PBS- and OVA-treated STAT6(-/-) mouse lungs compared with that in WT animals suggesting that STAT6 limits both naturally occurring and Ag-induced Tregs. Tregs obtained from either WT or STAT6(-/-) mice were equally efficient in suppressing CD4(+) T cell proliferation in vitro. Taken together, our studies demonstrate multiple STAT6-dependent and -independent features of allergic inflammation, which may impact treatments targeting STAT6.

HLA class II transgenic mice mimic human inflammatory diseases

Population studies have shown that among all the genetic factors linked with autoimmune disease development, MHC class II genes on chromosome 6 accounts for majority of familial clustering in the common autoimmune diseases. Despite the highly polymorphic nature of HLA class II genes, majority of autoimmune diseases are linked to a limited set of class II-DR or -DQ alleles. Thus a more detailed study of these HLA-DR and -DQ alleles were needed to understand their role in genetic predisposition and pathogenesis of autoimmune diseases. Although in vitro studies using class-II restricted CD4 T cells and purified class II molecules have helped us in understanding some aspects of HLA class-II association with disease, it is difficult to study the role of class II genes in vivo because of heterogeneity of human population, complexity of MHC, and strong linkage disequilibrium among different class II genes. To overcome this problem, we pioneered the generation of HLA-class II transgenic mice to study role of these molecule in inflammatory disease. These HLA class II transgenic mice were used to develop novel in vivo disease model for common autoimmune diseases such as rheumatoid arthritis, multiple sclerosis, insulin-dependent diabetes mellitus, myasthenia gravis, celiac disease, autoimmune relapsing polychondritis, autoimmune myocarditis, thyroiditis, uveitis, as well as other inflammatory disease such as allergy, tuberculosis and toxic shock syndrome. As the T-cell repertoire in these humanized HLA transgenic mice are shaped by human class II molecules, they show the same HLA restriction as humans, implicate potential triggering mechanism and autoantigens, and identify similar antigenic epitopes seen in human. This review describes the value of these humanized transgenic mice in deciphering role of HLA class II molecules in immunopathogenesis of inflammatory diseases.

Inhibition of NF-kappaB activation reduces the tissue effects of transgenic IL-13

IL-13 is a major Th2 cytokine that is capable of inducing inflammation, excessive mucus production, airway hyperresponsiveness, alveolar remodeling, and fibrosis in the murine lung. Although IL-13 through its binding to IL-4Ralpha/IL-13Ralpha1 uses the canonical STAT6-signaling pathway to mediate these tissue responses, recent studies have demonstrated that other signaling pathways may also be involved. Previous studies from our laboratory demonstrated that IL-13 mediates its tissue effects by inducing a wide variety of downstream genes many of which are known to be regulated by NF-kappaB. As a result, we hypothesized that NF-kappaB activation plays a critical role in the pathogenesis of IL-13-induced tissue alterations. To test this hypothesis, we compared the effects of transgenic IL-13 in mice with normal and diminished levels of NF-kappaB activity. Three pharmacologic approaches were used to inhibit NF-kappaB including 1) PS1145, a small molecule inhibitor of IkappaBalpha kinase (IKK2), 2) antennapedia-linked NF-kappaB essential modulator-binding domain (NBD) peptide (wild-type NBD), and 3) an adenoviral construct expressing a dominant-negative version of IKK2. We also crossed IL-13-transgenic mice with mice with null mutations of p50 to generate mice that overproduced IL-13 in the presence and absence of this NF-kappaB component. These studies demonstrate that all these interventions reduced IL-13-induced tissue inflammation, fibrosis and alveolar remodeling. In addition, we show that both PS1145 and wild-type NBD inhibit lung inflammatory and structural cell apoptosis. PS1145 inhibits caspase activation and up-regulates inhibitor of apoptosis protein cellular-inhibitor of apoptosis protein 1 (c-IAP-1). Therefore, NF-kappaB is an attractive target for immunotherapy of IL-13-mediated diseases.

Toxic oil syndrome: Genetic restriction and immunomodulatory effects due to adulterated oils in a model of HLA transgenic mice

Toxic oil syndrome (TOS) was described in Spain in 1981, due to the ingestion of contaminated rapeseed oil denatured with 2% aniline. More than 20,000 persons were affected, causing over 2500 deaths. Immunological findings were: eosinophilia, mRNA for Th2 cytokines (IL-4 and IL-5) in lungs, elevated total IgE and sIL-2R and increase of DR2 HLA class II phenotypic frequency in patients died by TOS. Our objective is to test the genetic restriction found in humans using HLA transgenic mice. Results show that mice expressing human DR2 and DQ6 (both in linkage disequilibrium), had higher percentage of eosinophils (DQ6) and IgE (DR2) than other transgenic mice tested (DR3 and DR4). Also, a Th2 shift was found in DR2 transgenic mice when toxic oil was administered with OVA. This has been corroborated by the IL-5 mRNA expression in 4 out of 6 lung tissues from TOS oil treated BALB/c mice. These data indicate that an immunological response was induced as consequence of the toxic administration. These results correlate with those found in TOS patients and reinforce the implication of genetic restrictions in the acquisition of toxic-mediated disease.

HLA-DQ8 is a predisposing molecule for detergent enzyme subtilisin BPN'-induced hypersensitivity

Several million individuals are exposed to agents in the workplace associated with atopy and asthma. Detergent enzymes have been implicated in occupationally induced hypersensitivity. However, the genetic susceptibility and T cell responses to detergent enzymes are undefined. We generated and used HLA-DQ6, -DQ8, -DR2, -DR3, and -DR4 transgenic mice to examine the immune and inflammatory components involved in the response to the detergent enzyme subtilisin BPN'. Based on in vitro and in vivo studies, for the first time, we present evidence that DQ8 is a strong susceptibility marker for BPN'-induced hypersensitivity. Only DQ8 mice showed consistent T cell responses to five immunodominant regions of BPN' comprising peptides #14 to 16, 36-37, 42-43, 62-63, and 80-81. The DQ8 mice also developed allergic eosinophilic inflammatory reactions in the airways following intranasal instillations of this enzyme. The DQ8 mice also responded to BPN' with a significant IgG1 and IgE production. We propose that the HLA Class II tg mice are useful for understanding allergenic responses to enzymes in humans, screening of allergenic and immunogenic properties of detergent enzymes, and for the development of modified enzymes to maintain efficient detergent qualities without allergic properties.

Blood concentrations of Th2-type immunoglobulins are selectively increased in weanling mice subjected to acute malnutrition

Male and female C57BL/6J mice, initially 19 days old, consumed a complete purified diet either ad libitum (age-matched control) or in restricted daily quantities (energy deficiency), or they consumed a purified isocaloric low-protein diet ad libitum (protein and energy deficit). In a 14-day experimental period, malnourished animals lost approximately 1.5% of their initial body weight daily. Zero-time controls, 19 days old, were also included in the study. Serum levels of Th2-type (IgG1 and IgE) and Th1-type (IgG2a and IgG3) immunoglobulins were quantified by enzyme-linked immunosorbent assay, and total IgG concentration was also assessed. Both malnourished groups exhibited high serum concentrations of IgG1 and IgE relative to the age-matched control group, whereas levels of the Th1-type immunoglobulins were unaffected. Total IgG concentration in the malnourished groups reflected the usual finding in humans (i.e., no effect or elevated). The results are consistent with the proposition of Th2-polarized immune competence in acute weanling deficiencies of energy, protein, or both.

Identification of antigenic epitopes on human allergens: studies with HLA transgenic mice

Environmental factors play an important role in the rise and manifestation of allergic conditions in genetically predisposed subjects. Increased exposure to indoor/outdoor allergens is a significant factor in the development of allergic sensitization and asthma. Recently, strong relationships between the immune response to several highly purified allergens and specific human leukocyte antigen (HLA)-DQ and -DR haplotypes have been reported. The major antigens from clinically important allergens have been cloned and sequenced. However, whether innate structural features of major allergens or peculiar immune recognition of these molecules contribute to the overly robust immune responses is not known. We generated and used transgenic (tg) mice expressing single HLA class II transgene(s) to characterize the allergen epitopes presented by particular HLA class II molecules. Next, we generated in vivo models for asthma in the HLA tg mice by intranasal challenge with allergenic extracts. Furthermore, we used a single epitope to induce an allergic lung inflammation. Our system offers a sophisticated technique for systematically identifying the genetic (individual human class II) and antigenic (individual allergenic epitopes) basis of asthma sensitivity and has important implications for new treatment strategies.

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.

HLA class II influences the immune response and antibody diversification to Ro60/Sjögren's syndrome-A: heightened antibody responses and epitope spreading in mice expressing HLA-DR molecules

Abs to Ro/SSA Ags in the sera of patients with systemic lupus erythematosus and Sjögren's syndrome are influenced by the HLA class II genes. To investigate the role of individual HLA class II genes in immune responses to human Ro60 (hRo60), mice lacking murine class II molecules and carrying either HLA genes DR2(DRB1*1502), DR3(DRB1*0301), DQ6(DQA1*0103/DQB1*0601), or DQ8(DQA1*0301/DQB1*0302), were immunized with rhRo60. The results show that hRo60 induces strong T and B cell responses in DR2, DR3, and DQ8 mice in comparison to weaker responses in DQ6 mice. In all mice, the majority of the dominant T cell epitopes were located in the amino portion (aa 61-185) and the carboxy portion (aa 381-525) of the hRo60 molecules. In contrast, the early dominant B cell epitopes were located in the middle and carboxy portion of the hRo60 molecule (aa 281-315 and 401-538). In DR2, DR3, and DQ8 mice, the B cell epitopes subsequently spread to the amino and carboxy portion of the hRo60 molecule but were limited to the middle and carboxy portion in DQ6 mice. The DR2 and DR3 mice produced the highest titers of immunoprecipitating Abs against hRo60 and native mouse Ro60. In addition, only DR2 mice exclusively produced immunoprecipitating Abs to native mouse Ro52 and Abs to mouse La by slot blot analysis, whereas in other strains of mice Abs to mouse La were cross-reactive with the immunogen. The results of the present study demonstrate the importance of HLA class II in controlling the immune responses to the Ro-ribonucleoprotein.

Distribution of intranasal instillations in mice: effects of volume, time, body position, and anesthesia

Intranasal instillation techniques are used to deliver various substances to the upper and lower respiratory tract (URT and LRT) in mice. Here, we quantify the relative distribution achieved with intranasal delivery of a nonabsorbable tracer, (99m)Tc-labeled sulfide-colloid. Relative distribution was determined by killing mice after instillation and quantifying the radioactivity in dissected tissues using gamma scintigraphy. A significant effect of delivery volume on relative distribution was observed when animals were killed 5 min after instillation delivered under gas anesthesia. With a delivery volume of 5 microl, no radiation was detected in the LRT; this increased to a maximum of 55.7 +/- 2.5% distribution to the LRT when 50 microl were delivered. The majority of radiation not detected in the LRT was found in the URT. Over the course of the following 1 h, radiation in the LRT remained constant, while that in the URT decreased and appeared in the gastrointestinal tract. Instillation of 25 microl into anesthetized mice resulted in 30.1 +/- 6.9% distribution to the LRT, while only 5.3 +/- 1.5% (P < 0.05) of the same volume was detected in the LRT of awake mice. Varying the body position of mice did not affect relative distribution. When using intranasal instillation, the relative distribution between the URT and LRT and the gastrointestinal tract is heavily influenced by delivery volume and level of anesthesia.

Cryptic determinants and promiscuous sequences on human acetylcholine receptor: HLA-dependent dichotomy in T-cell function

Experimental autoimmune myasthenia gravis can be induced in some strains of mice and rats by immunizing with acetylcholine receptor. Also, epidemiologic studies demonstrate an MHC linkage of myasthenia gravis in the man. In order to obtain direct experimental evidence for the influence of the genes of the MHC complex in the development of myasthenia gravis, we used mice transgenic to individual HLA molecules. We observed an increased susceptibility to the disease in HLA DQ8 transgenic mice compared to HLA DQ6 transgenic mice ( J. Immunol. 160:4169; 1998). These mice lacked endogenous mouse class II molecules. In the present study we mapped the cryptic and dominant sequences on the extra cellular region of human acetylcholine receptor. Although some epitopes (e.g., alpha11-30, alpha141-160, alpha171-190) were common between DQ8 and DQ6 transgenic mice, several others were disparately recognized. We also found a functional dichotomy in T cells from mice differing by one MHC molecule (HLA DQ8 or DQ6) when primed by sequences immunodominant in DQ8 and DQ6 tg mice. Differential disease manifestation in the two different HLA transgenic mice could be explained not only by differential recognition of peptides by these antigen presenting molecules, but also by the difference in the functional profile of T cells generated when primed by promiscuous sequence regions.

Allergic inflammatory response to short ragweed allergenic extract in HLA-DQ transgenic mice lacking CD4 gene

To investigate the role of HLA-DQ molecules and/or CD4(+) T cells in the pathogenesis of allergic asthma, we generated HLA-DQ6 and HLA-DQ8 transgenic mice lacking endogenous class II (Abeta(null)) and CD4 genes and challenged them intranasally with short ragweed allergenic extract (SRW). We found that DQ6/CD4(null) mice developed a strong eosinophilic infiltration into the bronchoalveolar lavage and lung tissue, while DQ8/CD4(null) mice were normal. However, neither cytokines nor eosinophil peroxidase in the bronchoalveolar lavage of DQ6/CD4(null) mice was found. In addition, the airway reactivity to methacholine was elevated moderately in DQ6/CD4(null) mice compared with the high response in DQ/CD4(+) counterparts and was only partially augmented by CD4(+) T cell transfer. The DQ6/CD4(null) mice showed Th1/Th2-type cytokines and SRW-specific Abs in the immune sera in contrast to a direct Th2 response observed in DQ6/CD4(+) mice. The proliferative response of spleen mononuclear cells and peribronchial lymph node cells demonstrated that the response to SRW in DQ6/CD4(null) mice was mediated by HLA-DQ-restricted CD4(-)CD8(-)NK1.1(-) T cells. FACS analysis of PBMC and spleen mononuclear cells demonstrated an expansion of double-negative (DN) CD4(-)CD8(-)TCRalphabeta(+) T cells in SRW-treated DQ6/CD4(null) mice. These cells produced IL-4, IL-5, IL-13, and IFN-gamma when stimulated with immobilized anti-CD3. IL-5 ELISPOT assay revealed that DN T cells were the cellular origin of IL-5 in allergen-challenged DQ6/CD4(null) mice. Our study shows a role for HLA-DQ-restricted CD4(+) and DN T cells in the allergic response.

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

BACKGROUND

Airway inflammation is central to the pathogenesis of allergic asthma, and molecules that mediate this process obviously represent targets for therapy.

OBJECTIVE

To study the role of CD4(+) T cells and/or HLA-DQ molecules in allergic asthma, we have generated and characterized models of short ragweed allergen (SRW)-induced inflammation using transgenic mice with HLA-DQ (DQ6 or DQ8), human CD4 (hCD4), or both on a genetic background that lacks mouse MHC II and CD4 (Abeta(0)/mCD4(0)).

METHODS

Mice were actively sensitized and later challenged intranasally with SRW allergenic extract. Bronchoalveolar lavage fluid composition, airway inflammation and hyperresponsiveness, blood eosinophil levels, and cell proliferation were examined.

RESULTS

In response to SRW treatment, both DQ6 and DQ8 transgenic mice expressing hCD4 developed pulmonary eosinophilia and associated lung tissue damage with increase in eosinophil peroxidase and T(H)2 cytokines in bronchoalveolar lavage fluid, strong airway hyperreactivity, and persistent blood eosinophilia. The response was independent of mast cells/histamine pathway and was mediated by DQ-restricted hCD4(+) T cells. Interestingly, lungs of CD4-deficient DQ6 transgenic mice showed an eosinophilic inflammation without local increase in cytokines and eosinophil peroxidase. The allergic reaction was absent in double-knockout mice and mice expressing either DQ8 or hCD4 alone.

CONCLUSIONS

DQ6 molecules are critical to SRW-induced allergy and can operate in the presence or absence of CD4. However, both DQ antigens and CD4 molecules are critical for full manifestation of allergen-induced asthma in transgenic mice.

Cockroach allergen-induced eosinophilic airway inflammation in HLA-DQ/human CD4(+) transgenic mice

Airway eosinophilic inflammation is a characteristic feature of allergic asthma. Exposure to allergens produced by the German cockroach (Blattella germanica) is a risk factor for allergic disease in genetically predisposed individuals, and has been linked to an increase in asthma morbidity among cockroach-sensitive inner city children. To determine the role and contribution of specific HLA class II in the pathogenesis of allergic airway inflammation in cockroach-induced asthma, we generated double-transgenic, double-knockout mice expressing human HLA-DQ8, HLA-DQ6, and CD4 molecules in the absence of mouse class II and mouse CD4. Mice were actively immunized and later challenged intranasally with cockroach allergen extract. These mice developed bronchoalveolar lavage fluid (BALF) eosinophilia and pulmonary eosinophilia. This was accompanied by an increase in total protein levels, IL-5, and IL-13 in BALF. There were also elevated levels of cockroach-specific serum IgG1 and total serum IgE. Histological analysis revealed peribronchial and perivascular eosinophilic inflammation in cockroach-treated mice. Other pathologic changes in the airways were epithelial cell hypertrophy and mucus production. Treatment with anti-DQ mAb significantly reduced pulmonary and BALF eosinophilia in cockroach allergen-sensitized mice. Abeta(0) mice and transgenic mice expressing human CD4 molecule alone (without class II) or human HLA-DQ8 molecule (without CD4) treated in the same fashion showed no eosinophilia in bronchoalveolar fluid and no pulmonary parenchymal inflammation. Our results provide direct evidence that HLA-DQ molecules and CD4 T cells mediate cockroach-induced eosinophilic inflammation in the airways.

HLA class II polymorphism influences onset and severity of pathology in Schistosoma mansoni-infected transgenic mice

Genetic factors that might influence susceptibility or resistance in naive individuals and early-stage pathology in schistosomiasis are difficult to study in clinical trials, since in areas where the disease is endemic the first contact with the parasite occurs most often at very early ages. Therefore, four strains (DR1.Abeta degrees, DR2.Abeta degrees, DQ8.Abeta degrees, and DQ6.Abeta degrees ) of major histocompatibility complex class II-deficient mice (Abeta degrees ), transgenic for different HLA alleles, have been used to evaluate the potential role of HLA class II polymorphism in the onset of the infection by Schistosoma mansoni. The survival rates and parasitological and immunological parameters after infection were evaluated and compared against the control values obtained with Abeta degrees mice. All four mouse strains used in this study were able to generate a specific immune response against S. mansoni antigens (cytokine production and antibody production). However, only mice expressing DR alleles survived until the chronic stage of the infection and were able to mount protective granulomatous response avoiding hepatic damage, presenting predominant gamma interferon production. In contrast, strains expressing DQ alleles revealed an impairment in generating effective granulomas, resulting in earlier death, which was associated with an impaired hepatic granulomatous response and liquefactic necrosis, reflecting the influence of HLA polymorphism in the establishment of protective response in the early stage of infection.

Immune response of HLA-DQ transgenic mice to house dust mite allergen p2: identification of HLA-DQ restricted minimal epitopes and critical residues

HLA-DQ8 (HLA-DQA1*0301; HLA-DQB1*0302) and HLA-DQ6 (HLA-DQA1*0103; HLA-DQB1*0602) genes were introduced into mouse class II (H-2A(o)(beta)) knockout mice. Transgenic HLA-DQ8 and HLA-DQ6 mice were individually immunized and challenged using synthetic peptides representing HDM (Dermatophagoides pteronyssinus) allergen p2. HLA-DQ8 mice responded to p2 peptides 1-20, 41-60, 51-70, 61-80, 91-110, and 101-120. HLA-DQ6 mice responded to peptides 1-20, 11-30, 21-40, 41-60, and 51-70. Using single amino acid truncated 30-mer peptides, residues necessary for HLA-DQ8 recognition were identified spanning regions 3-12, 50-70, and 91-120. A synthetic peptide comprising residues 3-12 was synthesized and a series of single alanine substitutions was introduced into the minimal peptide. Introduction of alanine residues at positions 3, 11, and 12 resulted in a significant loss of immune recognition. It was concluded that residues 4, 5, 7, 11, and 12 are critical for immune recognition by HLA-DQ8 mice.

HLA-DQ/human CD4-restricted immune response to cockroach allergens in transgenic mice

We investigated the immune response to the German cockroach (Blattella germanica), and one of its major antigens, Blattella germanica group 5 (Bla g 5), in a double-transgenic, double-knockout mouse expressing human HLA-DQ8, HLA-DQ6 and CD4 molecules in the absence of mouse class II and mouse CD4. Transgenic mice were primed and challenged with CR extract or individual synthetic peptides representing Bla g 5. Strong T-cell responses to CR extract were detected in both HLA-DQ/hCD4+ transgenic mice. The responses were two times lower in mice expressing HLA-DQ molecule in the context of mouse CD4. Under similar treatment, no responses were found in the double-knockout Abetadegrees/mCD4degrees mice and in mice expressing human CD4 molecule alone. HLA-DQ/hCD4+ mice produced primarily interleukin (IL)-5, IL-10, and IL-13. Minimal amounts of IL-4 were detected only in HLA-DQ6/ hCD4+ mice. Interferon (IFN)-gamma production was low in both transgenic mouse, suggesting a predominantly T-helper 2 (Th2)-type response. Cockroach allergen extract immunized HLA-DQ8/hCD4+ mice recognized only one of the 20 peptides of Bla g 5 while HLA-DQ6/hCD4+ mice responded primarily to three peptides. Primed with individual peptides, both HLA-DQ/hCD4+ mice responded maximally to peptides 10 (residues 91-110) and 17 (residues 161-180). In addition, HLA-DQ6/hCD4+ mice responded to peptide 16 (residues 151-170). Thus, peptides 10 and 17 contained the major HLA-DQ-restricted hCD4+ T-cell epitopes and could be recognized by both HLA-DQ8 and HLA-DQ6 transgenic mice. Transgenic mice represent a new tool for investigating the immune responses to cockroach allergen. Our results suggest that therapeutic strategies aimed at developing antagonist peptides might be a useful treatment (immunotherapy) for allergic asthma.