The pathology of asthma: brief review

Low Serum Levels of Zinc, Selenium, and Vitamin D3 Are Biomarkers of Airway Inflammation and Poor Asthma Control: A Two-Centre Study

Background Asthma is a chronic inflammatory disease with its control being affected by underlying oxidative stress. Trace elements, along with vitamin D3, play an important role in immune alterations leading to an imbalance of Th1/Th2 helper cells. However, their role in asthma pathogenesis and control is inconsistent and inconclusive. The objective of our study was to assess levels of serum trace elements like zinc, copper, selenium, iron, magnesium, vitamin D3 levels, IgE, and HsCRP in asthmatic children, compare with healthy controls, and assess their association with the level of asthma control. Methods A cross-sectional study was conducted from 2019 to 2021 enrolling 100 asthmatic children and 75 healthy controls. The level of asthma control was assessed as uncontrolled, partly controlled, and controlled asthma as per GINA Guidelines. Mean and standard deviation were calculated for each element and mean differences between groups were analyzed by student t-test. A p-value of <0.05 was considered significant. Results The mean age was 8.75±2.89 yrs in cases and 9.04±2.79 in controls. A total of 57.6% of cases had atopic comorbidities. The mean serum zinc levels were 51±12.8 mg/dl, which was very low in asthmatic children as compared to 60±18.2mg/dl (p-value 0.0002) in healthy controls. Serum selenium was 13±3 µg/dl in asthmatics vs. 15±4 µg/dl (p-value 0.0002) in healthy controls. Serum copper was 115.2±21.92µg/dl vs. 125.3±31.99µg/dl (p-value 0.015), Serum vitamin D3 levels were 13.07±7.82ng/ml vs. 17.82±14.62 ng/ml(p-value 0.006) in both groups, respectively. SIgE and HsCRP were high in asthmatic children suggestive of eosinophilic inflammation. Serum zinc was 49±5.45 mg/dl in the uncontrolled group, 53±6.1 in the partly controlled, and 58±8.0 in the well-controlled group (p<0.0001). Serum selenium was 10± 3.0 µg/dl in the uncontrolled group vs. 13± 2.0 and 14± 2.0 µg/dl in the partly controlled and well-controlled groups, respectively (p-value <0.0001). Vitamin D3 was significantly low (9.32±5.95ng/dl) in the uncontrolled group vs. 12.99±4.97 and 13.40±5.92 ng/dl(p<0.005) in the partly controlled and well-controlled groups respectively. Vitamin D3 showed a strong positive correlation with zinc (r=0.4,p< 0.0001) and a negative correlation with inflammatory markers like SIgE and HsCRP. Conclusion Children with asthma had low zinc, selenium, and vitamin D3 levels, and were associated with airway inflammation and poor asthma control.

The Ability of Resveratrol to Attenuate Ovalbumin-Mediated Allergic Asthma Is Associated With Changes in Microbiota Involving the Gut-Lung Axis, Enhanced Barrier Function and Decreased Inflammation in the Lungs

Asthma is a chronic respiratory disease highly prevalent worldwide. Recent studies have suggested a role for microbiome-associated gut-lung axis in asthma development. In the current study, we investigated if Resveratrol (RES), a plant-based polyphenol, can attenuate ovalbumin (OVA)-induced murine allergic asthma, and if so, the role of microbiome in the gut-lung axis in this process. We found that RES attenuated allergic asthma with significant improvements in pulmonary functions in OVA-exposed mice when tested using plethysmography for frequency (F), mean volume (MV), specific airway resistance (sRaw), and delay time(dT). RES treatment also suppressed inflammatory cytokines in the lungs. RES modulated lung microbiota and caused an abundance of Akkermansia muciniphila accompanied by a reduction of LPS biosynthesis in OVA-treated mice. Furthermore, RES also altered gut microbiota and induced enrichment of Bacteroides acidifaciens significantly in the colon accompanied by an increase in butyric acid concentration in the colonic contents from OVA-treated mice. Additionally, RES caused significant increases in tight junction proteins and decreased mucin (Muc5ac) in the pulmonary epithelium of OVA-treated mice. Our results demonstrated that RES may attenuate asthma by inducing beneficial microbiota in the gut-lung axis and through the promotion of normal barrier functions of the lung.

Tyrosol improves ovalbumin (OVA)-induced asthma in rat model through prevention of airway inflammation

Asthma is an inflammatory disease that affects many people around the world, especially persons at paediatric age group. The effectiveness of tyrosol, a natural phenolic compound, was examined in the asthma model induced by ovalbumin (OVA). For this purpose, four groups, each consisting of eight rats, were arranged. For 21 days, physiological saline solution was treated to the control group and OVA was treated to the groups of OVA, OVA + dexamethasone (Dexa) and OVA + tyrosol groups, intraperitoneally and through inhalation. Additionally, 0.25 mg/kg Dexa was treated to the OVA + Dexa group and 20 mg/kg tyrosol to the OVA + tyrosol group by oral gavage. Serum, blood, bronchoalveolar lavage fluid (BALF) and lung tissues of the rats were examined. It was observed that MDA level decreased, GSH level and GPx activity increased, and there was no change in CAT activity in lung tissues of the tyrosol treatment groups. It was also observed that NF-κB, TNF-α, IL-4, IL-5, IL-13, IFN-γ and IgE levels decreased compared to the OVA group in lung tissue and serum samples except for serum NF-κB and IL-4. However, no effect on IL-1 β level was observed. In addition, it was determined that tyrosol treatment increased the IL-10 level on both tissue samples. The results of the histopathological investigation of lung tissue showed that tyrosol significantly ameliorated OVA-induced histopathological lesions. Additionally, PAS staining showed that mucus hypersecretion was significantly reduced with the use of tyrosol. In addition, it was determined that the number of eosinophils decreased significantly in blood and BALF samples. The obtained results showed that tyrosol possessed antioxidant and anti-inflammatory features on OVA-induced rats and preserved tissue architecture.

Optical Microscopy and the Extracellular Matrix Structure: A Review

Biological tissues are not uniquely composed of cells. A substantial part of their volume is extracellular space, which is primarily filled by an intricate network of macromolecules constituting the extracellular matrix (ECM). The ECM serves as the scaffolding for tissues and organs throughout the body, playing an essential role in their structural and functional integrity. Understanding the intimate interaction between the cells and their structural microenvironment is central to our understanding of the factors driving the formation of normal versus remodelled tissue, including the processes involved in chronic fibrotic diseases. The visualization of the ECM is a key factor to track such changes successfully. This review is focused on presenting several optical imaging microscopy modalities used to characterize different ECM components. In this review, we describe and provide examples of applications of a vast gamut of microscopy techniques, such as widefield fluorescence, total internal reflection fluorescence, laser scanning confocal microscopy, multipoint/slit confocal microscopy, two-photon excited fluorescence (TPEF), second and third harmonic generation (SHG, THG), coherent anti-Stokes Raman scattering (CARS), fluorescence lifetime imaging microscopy (FLIM), structured illumination microscopy (SIM), stimulated emission depletion microscopy (STED), ground-state depletion microscopy (GSD), and photoactivated localization microscopy (PALM/fPALM), as well as their main advantages, limitations.

Erythromycin Releasing PVA/sucrose and PVA/honey Hydrogels as Wound Dressings with Antibacterial Activity and Enhanced Bio-adhesion

The present study deals with preparation and characterization of thermally crosslinked PVA-based hydrogels containing honey and sucrose for the purpose of erythromycin delivery. The hydrogels have been characterized and compared by scanning electron microscopy, Fourier transform infrared spectroscopy, and bio-adhesion tests. Swelling measurements showed that addition of sucrose and honey decreased the equilibrium swelling of the hydrogels. Results of release studies showed that the amount of erythromycin, released at the early hours was higher for PVA/sucrose and PVA/honey hydrogels compared to PVA hydrogel while the drug released at later times was highly reduced for PVA/honey hydrogel. Both Peppas-Sahlin and Korsmeyer-Peppas models fitted well to the release data. Fitting Peppas-Sahlin model to the release data showed that at the initial times, release of drug from the hydrogel network was mainly governed by Fickian mechanism; however, at later times the drug is dominantly released by relaxational mechanism due to swelling of the network,. Addition of honey improved the bio-adhesion of PVA/honey hydrogel as compared to PVA/sucrose and pure PVA hydrogel. Results of antibacterial tests showed growth inhibitory action of erythromycin-loaded PVA hydrogels against Pseudomonas aeruginosa and Staphylococcus aureus bacteria. This study indicates that these hybrid hydrogels are capable of being used as functional wound dressings aiming to control the rate of antibiotic delivery to the wound site and prevent the wounds from infection.

Association between trace elements levels and asthma susceptibility

BACKGROUND

It is well-documented that the dysregulation of trace elements may be involved in the pathogenesis of asthma. However, the precise changes of trace elements levels in asthma cases remain elusive. We established whether trace elements levels were associated with asthma susceptibility by pooling case-control studies.

METHODS

34 studies were included. We extracted the standard mean differences (SMDs) and corresponding 95% confidence intervals (CIs). A pooled-analysis was performed.

RESULTS

No marked difference (95% CI: -1.437-0.218, p = 0.149) of Se level between asthma and controls. Significant difference (95% CI: 0.112-1.032, p = 0.015; 95% CI: 0.376-1.331, p < 10^-4) of Cu level between asthma and controls was noted among overall populations and Asians. No marked difference of Zn level between asthma and controls was observed among overall populations, Asians, Caucasians and Africans. Significant difference (95% CI: -0.567 to -0.238, p < 10^-4) of Mg level between asthma and controls was noted among Asians. Marked difference (95% CI: 0.258-2.864, p = 0.019; 95% CI: 0.270-3.282, p = 0.021) of Fe level between asthma and controls was noted among overall populations and Asians. Age had no impact on the pooled SMDs of Se, Cu, Zn, Mg and Fe between asthma and controls. Sensitivity analyses did not change the overall results. No publication bias was noted for overall populations.

CONCLUSIONS

Alterations of Cu, Mg and Fe levels may be a biomarker of asthma risk among specific populations. Further studies should be performed to clarify the strength of these elements in asthma.

Asthmatic granulomatosis as a rare variant of uncontrolled severe asthma

Asthmatic granulomatosis (AG) is a variant of severe asthma, first described in 2012, that consists of small airway changes compatible with asthma as well as interstitial nonnecrotizing granulomas. Treatment of AG requires immunosuppression as opposed to the traditional asthma therapy of inhaled steroids. We describe a 5-year course of a patient with AG that has shown no improvement with immunosuppression or other standards of therapy.

ITGB4 deficiency in bronchial epithelial cells directs airway inflammation and bipolar disorder-related behavior

BACKGROUND

Chronic persistent airway inflammation has been associated with the comorbidity of asthma and bipolar disorder (BD). However, the direct relevance between airway inflammation and BD-like psychiatric comorbidity is almost unknown. Integrin β4 (ITGB4) is downregulated on the airway epithelial of asthma patients, which might play a critical role in the parthenogenesis of airway inflammation. So this study aimed to examine the role of ITGB4 deficiency in mediating airway inflammation and further leading to the BD-like behaviors.

METHODS

ITGB4^-/- mice were generated by mating ITGB4^fl/fl mice with CCSP-rtTA^tg/-/TetO-Cretg/tg mice. Mania-like behavior tests were performed, including hyperlocomotion, D-amphetamine-induced hyperactivity, open-field test, and elevated plus-maze test. Depressive-like behavior tests were carried out, including sucrose preference, forced swimming, and learned helplessness. Inflammatory cells (Th17, Th1, Th2) in the lung were examined by flow cytometry. Futhermore, inflammatory cytokines (IL-4, IL-13) in bronchoalveolar lavage fluid and sera were detected by ELISA. Protein expression of the IL-4Rα on choroid plexus, microglial marker (IBA1), and synapse-associated proteins (synaptophysin, SYP) in the hippocampus and prefrontal cortex were examined by western blotting. Additionally, proinflammatory cytokines (IL-1β, IL-6, and TNF-α) in the hippocampus and prefrontal cortex were detected by immunohistochemistry. Inflammatory disorder in the lung, hippocampus, and prefrontal cortex was tested by hematoxylin and eosin (H&E) staining. And cell apoptosis in the hippocampus and prefrontal cortex was measured by TUNEL test.

RESULTS

ITGB4^-/- mice exhibited mania-like behavior, including hyperlocomotion, D-amphetamine-induced hyperactivity, and reduced anxiety-like behavior. While under stressful conditions, ITGB4^-/- mice manifested depressive-like behavior, including anhedonia, behavioral despair, and enhanced learned helplessness. At the same time, ITGB4^-/- mice mainly exerted Th2-type inflammation in periphery, like the number and major cytokines IL-4 and IL-13 of Th2-type inflammation. ITGB4^-/- mice also showed a significant increase of microglia and pro-inflammatory cytokines such as IL-1β, IL-6, and TNF-α in the hippocampus and prefrontal cortex. Additionally, neuron damage, increased neuron apoptosis, and the decrease of SYP were found in ITGB4^-/- mice.

CONCLUSIONS

These findings confirmed that airway inflammatory induced by ITGB4 deficiency is the important incentive for the BD-like behavior during asthma pathogenesis. The ITGB4-deficient mice provide a validated animal model for us to study the possible mechanism of BD-like psychiatric comorbidity of asthma patients.

Anti-asthmatic and anxiolytic effects of Herissantia tiubae, a Brazilian medicinal plant

Herissantia tiubae (HtE) is a Brazilian plant used in folk medicine to treat inflammatory diseases. Our aim was to determine whether the HtE has anti-inflammatory and anxiolytic effects in a murine model of asthma. Ovalbumin (OVA)-sensitized BALB/c mice were treated with HtE (50, 100, or 200 mg/kg) or dexamethasone before each OVA challenge. After the last challenge, animals were subjected to anxiety tests and respiratory measurements. Following euthanasia, we quantified immune cells in the bronchoalveolar lavage (BAL), serum IgE titer and cytokine levels, cellular infiltration and mucus content in the lung tissues, and cellular composition of the mediastinal lymph nodes. OVA challenge in sensitized animals caused: (1) reduction of mean respiratory and dominant respiratory rate (from 398 ± 12 to 286 ± 20 cicles per minute (cpm) and from 320 ± 14 to 162 ± 15 cpm, respectively); (2) increase in behavioral markers of anxiety tests; (3) substantial pro-inflammatory effects, including rise in OVA-specific IgE titer (from 0 to 1:2048) and these inflammatory effect diminished the titer to 1:512 after HtE treatment; rise in plasma IL-13 (from 13 ng/mL in saline to 227 ng/mL in OVA and HtE treatment restored to 1.29 ng/mL; rise in total BAL cell count (from 0.742 cells/mL in saline to 11.77 cells/mL in OVA), with prominent eosinophilia. H. tiubae extract affected respiratory parameters similarly to aminophylline, behavioral changes comparable to diazepam, and inflammation being as efficient as dexamethasone. H. tiubae extract (HtE) possesses both anti-inflammatory and anxiolytic properties in the murine model of asthma.

Localization of matrix metalloproteinase (MMP)-9 in lung tissue of a murine model of allergic asthma

MMP-9 (gelatinase B) is recognized in chronic obstructive pulmonary disease (COPD) and now asthma as playing a central role in matrix degradation in injury, as well as contributing to the remodeling process. The increasing focus on MMP-9 in human and animal research supports the need for a reliable immunostain in lung tissue. However, MMP-9 immunostaining in murine systems is hampered by several factors. First, many of the anti-human antibodies do not readily cross-react with murine MMP-9 despite the high degree of conservation between human and murine MMP-9. Secondly, the availability of detailed protocols is limited. Lung MMP-9 immunostaining is further complicated by technical issues such as edge effect, availability of positive and negative controls, antigen retrieval, staining specificity, and the need to achieve a delicate balance of primary and secondary antibody concentrations, and colorimetric reagents which will allow visualization of specific cell expression in highly delicate lung tissue, while also demonstrating adequate uptake in (extra-pulmonary) tissue controls. We describe a detailed method for immunostaining MMP-9 in mouse lung paraffin-embedded tissue utilizing human ovary as a control since MMP-9 is known to be over-expressed in human ovarian carcinomas.

[Controversies in the association between type 1 diabetes and asthma]

OBJECTIVE

Critical review of the literature to investigate the relationship between asthma and type 1 diabetes mellitus (DM1).

SOURCE OF DATA

Bibliography search in MEDLINE and LILACS databases in the last twenty years.

SUMMARY OF DATA

Several studies demonstrate an inverse relationship between asthma, atopic diseases and the risk to develop DM1. According to the "Hygiene Hypothesis", the risk of allergic diseases decreases with infections early in childhood, towards distance of Th2 profile, common at birth, to the Th1 phenotype. Other articles described lack of association or positive association between DM1 and allergies. There is a possibility of environmental factors interfering in the development of disorders mediated by Th1 and Th2 cells, in the same individual, due to the absence of immunomodulatory mechanisms mediated by interleukin-10 and regulatory cells.

CONCLUSION

The existing information about the inverse association between Th1-mediated diseases (e.g., DM1), and those that are Th2-mediated (e.g., allergies) are conflicting requiring more investigation to explain this question.

B and T lymphocyte attenuator regulates T cell survival in the lung

The initiation, intensity, and duration of T cell-directed inflammatory responses are dependent upon the coordination of both activating and inhibitory signals mediated by specific receptors on the T lymphocyte. The recently described receptor, B and T lymphocyte attenuator (BTLA), has been demonstrated to have an important role in limiting the duration of inflammation in a murine model of allergic asthma. In this study, we have examined the role of BTLA on the proliferation, recruitment, and survival of T cells in response to inhaled allergen. We find that there is decreased cell death in T cells from BTLA-deficient mice, whereas proliferation and recruitment to the lungs are unchanged. Thus, the regulation of cell death through BTLA signaling is a key determinant of the inflammatory response in the lung.

Role of eosinophil chemotactic factor by T lymphocytes on airway hyperresponsiveness in a murine model of allergic asthma

Airway hyperresponsiveness (AHR) is an important feature of bronchial asthma. Although the incidence of AHR has genetic and environmental components, the mechanism of AHR in asthma remains unclear. The identification of genes that are preferentially expressed in a murine model of AHR could help elucidate the molecular mechanisms of this pulmonary pathology. Suppressive subtractive hybridization analysis revealed that eosinophil chemotactic factor by T lymphocytes (ECF-L), a mouse chitinase family protein, was selectively expressed in the lungs of mice with AHR. Induction of ECF-L expression was observed soon after allergen exposure but before the onset of airway inflammation. Cell-specific ECF-L expression was examined by in situ hybridization using digoxigenin-labeled antisense RNA probes and immunofluorescence staining. The assay revealed that the ECF-L-expressing cells in the lungs of the AHR-model mice are alveolar macrophages. Intratracheal administration of an adenoviral vector that expressed antisense ECF-L RNA (Ad-ECF-L-AS) suppressed AHR and eosinophil infiltration. These results indicate that ECF-L may play a critical role in allergic inflammation and bronchial asthma.

Asphyxia by Tracheobronchial Thrombus

Asphyxia secondary to airway obstruction has numerous underlying causes, both acute and chronic. Causes of chronic airway obstruction, such as neoplasms and tracheal scarring, are often clinically apparent well prior to asphyxia. Causes of acute airway obstruction may not be as obvious to clinicians or investigators. These include infections, anaphylactic reactions, status asthmaticus, inhalational injuries, and aspirations, which may result in acute obstruction and sudden death. We report the deaths of 2 individuals, a 43-year-old female and a 78-year-old female, both with adenocarcinoma. The 43-year-old was hospitalized with a stage III, poorly differentiated infiltrating ductal carcinoma of the breast metastatic to the lymph nodes. She was intubated to treat poor respiratory function and acidosis. A bronchoalveolar lavage was consistent with alveolar hemorrhage; no organisms were identified. Blood and "clot" were in her endotracheal tube, so the endotracheal tube was replaced. She became comatose and life support was withdrawn. At autopsy, a large red-gray thrombus obstructed the trachea and extended into the right bronchus. Microscopically, the entire clot was composed of fibrin, red blood cells, and some mucus. Findings of acute respiratory distress syndrome with hyaline membranes were identified. The cause of death was listed as acute respiratory distress syndrome with tracheobronchial thrombus. Experiencing a decline in mental status, the 78-year-old had metastatic adenocarcinoma of unknown primary. She developed sudden respiratory distress and an airway obstruction was discovered. After failure to relieve the obstruction, she decompensated and died. At autopsy, a large, red-gray thrombus obstructed the distal trachea and both bronchi. Microscopically, the thrombus was composed of fibrin, platelets, and red blood cells. The cause of death was asphyxia secondary to airway obstruction by thrombus. We present these 2 unusual cases of asphyxia and review of the literature focusing on asphyxia and the etiology of airway thrombi.

Cissampelos sympodialis Eichl. (Menispermaceae): oral treatment decreases IgE levels and induces a Th1-skewed cytokine production in ovalbumin-sensitized mice

The murine model of ovalbumin (OVA)-induced allergy was used to evaluate the effectiveness of oral treatment with the leaf extract of Cissampelos sympodialis Eichl. (Menispermaceae) (CS) in the modulation of immunoglobulin E (IgE) production and T cell activation. CS treatment with doses ranging from 200 to 600 mg/Kg/day for 15 days before and during OVA-sensitization promoted reduction in total and OVA-specific serum IgE. CS at 400 or 600 mg/Kg/day also reduced paw edema induced by local OVA challenge. Daily intake of up to 600 mg/Kg of oral CS by BALB/c mice did not reduce weight gain, which is indicative of a lack of systemic toxicity. To assess the effect of CS treatment on T cell proliferative response to stimuli in vitro, the mitogenic response of spleen cells of treated and control animals were evaluated. Cells from CS-treated animals showed an elevated background proliferative response to concanavalin-A (Con-A) when compared to those from control animals. Oral intake of CS increased the in vitro production of IFN-gamma and IL-10 by Con-A stimulated cells. Mice treated with 200 mg/Kg/day CS showed increasing levels of IFN-gamma. These results show that oral treatment with Cissampelos sympodialis extract has an immunomodulatory effect, reducing allergy-associated responses possibly by a preferential activation of Th1-type cytokines.

3D-QSAR studies on thieno[3,2-d]pyrimidines as phosphodiesterase IV inhibitors

Cyclic nucleotide phosphodiesterase IV (PDE IV) inhibitors find utility in asthma and Chronic Obstructive Pulmonary Disease (COPD) therapy. A series of 29 thieno[3,2-d]pyrimidines with affinity for PDE IV was subjected to three dimensional quantitative structure activity relationship (3D-QSAR) studies using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). Both CoMFA and CoMSIA provided statistically valid models with good correlative and predictive power. The incorporation of hydrophobic, hydrogen bond donor and hydrogen bond acceptor fields showed insignificant improvement in CoMSIA model. The 3D-QSAR models provide information for predicting the affinity of related compounds and designing more potent inhibitors.

Measurement of airway inflammation in asthma

Chronic airway inflammation is considered responsible for symptoms and disorders of airway function associated with asthma. This process is the target of anti-inflammatory therapy, so a number of standardized, noninvasive techniques have been developed to assess it. More recent approaches include the measurement of exhaled gases and nonvolatile substances in breath condensate. Results from studies using a wide variety of inflammatory markers have shown group differences between patients with asthma and healthy control subjects, but evidence for the diagnostic use of these markers in individual patients is scarce. Similarly, despite many studies demonstrating some correlation between markers of airway inflammation and a measure of disease control, none has yet convincingly shown a place for the use of these markers in an individual with corticosteroid-treated asthma. However, application of these markers continues to further our understanding of the disease process and provides the potential for more appropriate, customized therapy.

Expression of the Ym2 lectin-binding protein is dependent on interleukin (IL)-4 and IL-13 signal transduction: identification of a novel allergy-associated protein

Asthma pathophysiology is intimately regulated by CD4(+) Th2 lymphocytes and the cytokines interleukin (IL)-4 and IL-13. However, the mechanisms by which these cytokines promote disease have not been fully elucidated. In order to identify novel molecular mediators of allergy, a comparison was made of the bronchoalveolar lavage, which demonstrated that the Ym2 protein was abundantly up-regulated in the lung during the development of allergy. Low levels of the Ym1 isomer were also detected. Importantly, neither Ym1 nor Ym2 has been characterized previously in the context of allergic pulmonary inflammation. Western immunoblot showed that enhanced expression of these proteins was dependent on CD4(+) T cells and IL-4 or IL-13 signaling via the IL-4Ralpha subunit. In addition, intratracheal instillation of IL-13 into naive mice was sufficient to induce expression. Ym1 is homologous to eosinophil chemotactic factor L. However, only weak eosinophil chemotaxis was observed in response to Ym protein in both in vitro and in vivo assays. By contrast, the homology of Ym1 and Ym2 to proteins associated with tissue remodeling, together with the previous findings that Ym1 is homologous to chitinase and binds heparin sulfate and GlcN oligomers (chitobiose, chitotriose, and chitotetraose), strongly suggests these proteins play an important role in airway wall remodeling in the allergic lung.