Subepithelial Collagen Deposition Research Articles

Dual Roles of CD40 on Microbial Containment and the Development of Immunopathology in Response to Persistent Fungal Infection in the Lung

Persistent pulmonary infection with Cryptococcus neoformans in C57BL/6 mice results in chronic inflammation that is characterized by an injurious Th2 immune response. In this study, we performed a comparative analysis of cryptococcal infection in wild-type versus CD40-deficient mice (in a C57BL/6 genetic background) to define two important roles of CD40 in the modulation of fungal clearance as well as Th2-mediated immunopathology. First, CD40 promoted microanatomic containment of the organism within the lung tissue. This protective effect was associated with: i) a late reduction in fungal burden within the lung; ii) a late accumulation of lung leukocytes, including macrophages, CD4+ T cells, and CD8+ T cells; iii) both early and late production of tumor necrosis factor-α and interferon-γ by lung leukocytes; and iv) early IFN-γ production at the site of T cell priming in the regional lymph nodes. In the absence of CD40, systemic cryptococcal dissemination was increased, and mice died of central nervous system infection. Second, CD40 promoted pathological changes in the airways, including intraluminal mucus production and subepithelial collagen deposition, but did not alter eosinophil recruitment or the alternative activation of lung macrophages. Collectively, these results demonstrate that CD40 helps limit progressive cryptococcal growth in the lung and protects against lethal central nervous system dissemination. CD40 also promotes some, but not all, elements of Th2-mediated immunopathology in response to persistent fungal infection in the lung.

TH2 heterogeneity: Does function follow form?

T(H)2 immune responses are required for the 2 fundamental pathological processes characteristic of allergic disease: IgE-mediated hypersensitivity and eosinophilic inflammation. The 3 established T(H)2 cytokines, IL-4, IL-5, and IL-13, each play a nonredundant role in allergic disease pathology. The recent explosion of T(H) subpopulations combined with the wide availability of polychromatic cytokine staining has facilitated the discovery of T(H)2 lineage heterogeneity. In this article we review T(H)2 heterogeneity and ask the following question: At what point do these subpopulations graduate from in vitro curiosities to immunologically robust therapeutic targets? We propose criteria to establish a T-cell subset as a biologically relevant entity and address the evidence to support these T(H)2 subpopulations having a unique function or specific contribution to allergic pathology or host defense.

Connective tissue growth factor expression is increased in collagenous colitis and coeliac disease

Subepithelial collagen deposition is a classical feature of collagenous colitis (CC), but is also seen in untreated coeliac disease. The end-stage mediator of excess cellular collagen production is connective tissue growth factor (CTGF). The aim of this study was to investigate CTGF expression by in situ hybridization (ISH) and polymerase chain reaction (PCR) in CC and coeliac disease as well as lymphocytic colitis (LC), Crohn's colitis and ulcerative colitis (UC). For coeliac disease we analysed fresh frozen material by quantitative reverse transcription-polymerase chain reaction (RT-PCR) and archival material for ISH. PCR transcripts in coeliac disease were moderately elevated and labelled cells were significantly increased in the subepithelial zone. For CC, LC and UC we investigated archival material because of the rarity of the first two conditions. There was a marked increase in CTGF expression in the subepithelial zone in CC, localizing to cells with the morphology of smooth muscle cells, which was not seen in LC. The colocalization of CTGF transcripts with areas of excessive collagen deposition in coeliac disease and CC suggest that it might be the end-stage mediator of local fibrosis in these conditions.

Gastrointestinal: Collagenous Sprue

A 66-year-old woman with no past medical history presented for further evaluation of chronic diarrhea. Five months previously, she had a sudden-onset of watery, large volume stools that occurred four to six times per day. After one month of persistent symptoms, she underwent an upper endoscopy which revealed the small bowel mucosa to be diffusely abnormal with mucosal granularity, scalloping, and a fine mosaic mucosal pattern with cobblestoning and whitish villi (Figure 1). Small bowel biopsies showed villous atrophy and increased intraepithelial lymphocytes with a mixed population of lymphocytes, plasma cells, and eosinophils (Figure 2). Serologic testing for celiac disease with both IgA and IgG tissue transglutaminase antibodies was negative. Human leukocyte antigen (HLA) haplotype testing showed positivity for HLA DQ2 and HLA DQ8. A presumptive diagnosis of serologically negative celiac disease was made and she was initiated on and compliant with a gluten-free diet for two months without any improvement in diarrhea. Because of persistent symptoms, she was referred for further evaluation. On further review of the small bowel biopsy, in addition to villous atrophy and increased intraepithelial lymphocytes, there was thickening (>10 micrometer) of the subepithelial collagen band (Figure 2, arrow); findings diagnostic of collagenous sprue. In most malabsorptive disorders, histopathologic examination of the small bowel biopsy is not diagnostic as there is a limited spectrum of mucosal response to injury. However, in some cases there may be specific histologic features present that may be diagnostic. The malabsorptive disorders with diagnostic histologic features include: Whipple's disease, abetalipoproteinemia, intestinal lymphangiectasia, giardiasis, lymphoma, autoimmune enteropathy, and collagenous sprue. Collagenous sprue is a clinicopathological entity characterized by chronic diarrhea and malabsorption with the histological findings of subepithelial collagen deposition and villous atrophy of the small intestinal mucosa. The only histologic feature that differentiates it from celiac disease is the thickened subepithelial collagen band. Weinstein et al. introduced the term ‘collagenous sprue’ in a report in the New England Journal of Medicine in 1970 in which they described an individual with malabsorption who was initially thought to have celiac disease but failed to respond to a gluten-free diet (GFD). Traditional thinking is that collagenous sprue is a complication of celiac disease. However, many patients with collagenous sprue have no evidence of celiac disease and collagenous sprue may represent the final result of a mucosal insult other than gluten sensitivity. The etiology of collagenous sprue is unknown but immune-mediated mechanisms are likely given initial responses to immunosuppressive therapy. Regardless of the etiology, collagenous sprue is thought to portend a poor prognosis with severe morbidity and mortality. Our patient was started on budesonide 9 mg daily and after three days had a complete resolution of diarrhea. The budesonide was subsequently tapered with a recurrence of diarrhea at budesonide 3 mg daily. She has been maintained on budesonide 6 mg daily without adverse sequelae. Clinical improvement on a GFD is an important component of diagnosing celiac disease. Lack of response to a GFD should raise the possibility of alternative diagnoses and small bowel biopsies should then be reviewed by an expert pathologist to exclude other diagnoses. Duodenal intraepithelial lymphocytosis and villous atrophy may occur in other small bowel disorders including collagenous sprue. Contributed by

Eosinophils Are Dispensable for Allergic Remodeling and Immunity in a Model of House Dust Mite–induced Airway Disease

Current thinking accredits eosinophils with preeminent contributions to allergic airway responses, including a major role in the development of airway remodeling, a process thought to significantly contribute to airway dysfunction. However, direct evidence in support of this notion is limited and often controversial. We elucidated the requirement for eosinophils in the generation of allergic sensitization, airway inflammation, and remodeling in a model involving chronic respiratory exposure to house dust mite (HDM). We used three methods to selectively eliminate eosinophils, a depleting antibody (anti-CCR3), and two strains of eosinophil-deficient mice (ΔdblGATA and the transgenic line PHIL). Anti-CCR3 treatment markedly reduced pulmonary eosinophilia (> 80%) over the course of HDM exposure but had no effect on the remaining inflammatory response, the extent of lung Th2 cells, or the development of remodeling-associated changes, including subepithelial collagen deposition and smooth muscle thickening. In addition, we observed that, despite the absence of eosinophils, HDM-exposed GATA mice mounted robust airway and lung inflammation and hyperresponsiveness and showed a remodeling response equivalent to that observed in wild-type mice. Moreover, these mice had similar serum HDM-specific IgE levels and Th2-associated splenocyte cytokine production as HDM-exposed wild-type control mice. Similar observations were made in PHIL eosinophil-deficient mice subjected to chronic HDM exposure, although slight decreases in airway mononuclear cells, but not lung Th2 cells, and remodeling were noted. Collectively, these data demonstrate that, at variance with the prevailing paradigm, eosinophils play negligible roles in the generation of HDM-induced allergic immunity and airway remodeling.

Effects of Arkadia on airway remodeling through enhancing TGF-β signaling in allergic rats

Upregulation of transforming growth factor-β (TGF-β) signaling is interrelated with the development of airway remodeling. In this study, we examined the role of two E3 ubiquitin ligases, Arkadia and Smurf2, which are critically required for TGF-β signaling in airway remodeling. Rats were immunized with ovalbumin (OVA) and then challenged with an OVA aerosol. In in vitro experiments, normal human bronchial epithelial cells were stimulated with TGF-β1 with or without the preincubation of Arkadia/Smurf2 small interfering RNA (siRNA) or lactacystin (an inhibitor of proteasomal degradation). In the lungs of OVA-treated rats, a large number of inflammatory cells were present near the airways. An increased subepithelial collagen deposition was associated with high expression levels of Smad7, SnoN and Ski mRNAs, Arkadia, Smurf2, and TGF-β type I receptor (TβRI), but low expression levels of Smad7, SnoN and Ski proteins. Smad7, SnoN and Ski interacted with both Arkadia and Smurf2 while TβRI only interacted with Smurf2 but not with Arkadia. In in vitro experiments, the inhibitory effect of TGF-β1 on the expression of Smad7, SnoN and Ski was reversed by Arkadia siRNA and lactacystin, whereas the stimulatory effect of TGF-β1 on the expression of TβRI protein and Smad7/SnoN/Ski mRNAs was not affected. In contrast, Smurf2 siRNA did not influence the effects of TGF-β1 on the expression of the above proteins. Our results suggest that Arkadia may contribute to the pathogenesis of airway remodeling through enhancing TGF-β signaling by inducing the reduction of Smad7, SnoN and Ski proteins in OVA-sensitized and -challenged rats.

Overexpression of Smad2 Drives House Dust Mite–mediated Airway Remodeling and Airway Hyperresponsiveness via Activin and IL-25

Airway hyperreactivity and remodeling are characteristic features of asthma. Interactions between the airway epithelium and environmental allergens are believed to be important in driving development of pathology, particularly because altered epithelial gene expression is common in individuals with asthma. To investigate the interactions between a modified airway epithelium and a common aeroallergen in vivo. We used an adenoviral vector to generate mice overexpressing the transforming growth factor-beta signaling molecule, Smad2, in the airway epithelium and exposed them to house dust mite (HDM) extract intranasally. Smad2 overexpression resulted in enhanced airway hyperreactivity after allergen challenge concomitant with changes in airway remodeling. Subepithelial collagen deposition was increased and smooth muscle hyperplasia was evident resulting in thickening of the airway smooth muscle layer. However, there was no increase in airway inflammation in mice given the Smad2 vector compared with the control vector. Enhanced airway hyperreactivity and remodeling did not correlate with elevated levels of Th2 cytokines, such as IL-13 or IL-4. However, mice overexpressing Smad2 in the airway epithelium showed significantly enhanced levels of IL-25 and activin A after HDM exposure. Blocking activin A with a neutralizing antibody prevented the increase in lung IL-25 and inhibited subsequent collagen deposition and also the enhanced airway hyperreactivity observed in the Smad2 overexpressing HDM-exposed mice. Epithelial overexpression of Smad2 can specifically alter airway hyperreactivity and remodeling in response to an aeroallergen. Moreover, we have identified novel roles for IL-25 and activin A in driving airway hyperreactivity and remodeling.

TGF-β Isoform Specific Regulation of Airway Inflammation and Remodelling in a Murine Model of Asthma

The TGF-β family of mediators are thought to play important roles in the regulation of inflammation and airway remodelling in asthma. All three mammalian isoforms of TGF-β, TGF-β1–3, are expressed in the airways and TGF-β1 and -β2 are increased in asthma. However, there is little information on the specific roles of individual TGF-β isoforms. In this study we assess the roles of TGF-β1 and TGF-β2 in the regulation of allergen-induced airway inflammation and remodelling associated with asthma, using a validated murine model of ovalbumin sensitization and challenge, and isoform specific TGF-β neutralising antibodies. Antibodies to both isoforms inhibited TGF-β mediated Smad signalling. Anti-TGF-β1 and anti-TGF-β2 inhibited ovalbumin-induced sub-epithelial collagen deposition but anti-TGF-β1 also specifically regulated airway and fibroblast decorin deposition by TGF-β1. Neither antibody affected the allergen-induced increase in sub-epithelial fibroblast-like cells. Anti- TGF-β1 also specifically inhibited ovalbumin-induced increases in monocyte/macrophage recruitment. Whereas, both TGF-β1 and TGF-β2 were involved in regulating allergen-induced increases in eosinophil and lymphocyte numbers. These data show that TGF-β1 and TGF-β2 exhibit a combination of specific and shared roles in the regulation of allergen-induced airway inflammation and remodelling. They also provide evidence in support of the potential for therapeutic regulation of specific subsets of cells and extracellular matrix proteins associated with inflammation and remodelling in airway diseases such as asthma and COPD, as well as other fibroproliferative diseases.

Gluten-Free Diet and Steroid Treatment Are Effective Therapy for Most Patients With Collagenous Sprue

Collagenous sprue (CS) is characterized by the presence of a distinctive band of subepithelial collagen deposition in the small bowel. We evaluated the clinical characteristics, treatments, and outcomes of patients with CS. Thirty patients with CS were identified at the 3 Mayo Clinic sites between 1993 and 2009. Clinical data from medical records were reviewed. The study cohort was 70% female (age range, 53-91 years). Most patients had severe diarrhea and weight loss. Hospitalization to treat dehydration was necessary in 16 (53%) patients. Associated immune-mediated diseases were noted in 70% of the patients; celiac disease was the most frequent. Other associated diseases were microscopic colitis, hypothyroidism, and autoimmune enteropathy. The median thickness of the layer of subepithelial collagen deposition in the small bowel was 29 mum (20-56.5 mum). Subepithelial collagen deposition in the colon or stomach was noted in 8 patients. A clinical response was observed in 24 (80%) patients after treatment with a combination of a gluten-free diet and immunosuppressive drugs. Histologic improvement was confirmed in 9 patients, with complete remission in 5. Two patients died (1 of complications of CS and 1 of another illness). Most patients with CS are treated effectively with a combination of gluten-free diet and steroids. CS is often associated with collagen deposition or chronic inflammation in other segments of the gastrointestinal tract as well as other immune-mediated disorders.

Linear mucosal defects: a characteristic endoscopic finding of lansoprazole-associated collagenous colitis

copathologic entity characterized by chronic watery diarrhea and, histologically, by the subepithelial deposition of collagen [1,2]. Some luminal antigens, including nonsteroidal anti-inflammatory drugs (NSAIDs) and proton pump inhibitors (PPIs), particularly lansoprazole, are thought to contribute to the development of collagenous colitis. On endoscopy, collagenous colitis usually shows no orminimal nonspecific abnormalities. However, a recent report showed that “linearmucosal defects”, including mucosal tears and sharp longitudinal ulcers, are characteristic colonoscopic findings of lansoprazoleassociated collagenous colitis [3]. We report a case of lansoprazole-associated collagenous colitis that showedmultiple linearmucosal defects in the colon. A 67-year-old womanwas referred to our hospital with a 1-month history of continuous watery diarrhea and abdominal pain. The patient had been taking 15mg of lansoprazole daily for the past 4 months for gastroesophageal reflux disease. She had no previous history of other gastrointestinal disease. The left lower abdomen was painful on palpation. A stool culture was negative for any enteric pathogens. Colonoscopy revealed a linear mucosal defect surrounded by edematous mucosa in the descending colon (l Fig. 1) and the proximal sigmoid colon (l Fig. 2). In addition, a linear and scarred mucosal defect was observed in the distal sigmoid colon (l Fig. 3). The sharply demarcated margin of the mucosal defect differentiated it from ischemic colitis. Multiple biopsy specimens, including those around the mucosal defect, were found to have thickened subepithelial collagen bands and inflammation of the lamina propria (l Fig. 4). This patient’s clinical and histological findings were compatible with the diagnosis of collagenous colitis. After discontinuation of lansoprazole treatment, the patient’s symptoms improved. Although the endoscopic finding in collagenous colitis is generally considered to be normal or near-normal mucosa, observation of a linear mucosal defect is useful for diagnosis of lansoprazole-associated collagenous colitis.

Celiac disease with a mixed pattern: a case report

IntroductionCeliac disease can be severe and associated with progressive malabsorption and death. A subset of patients may develop subepithelial collagen deposition, a condition referred to as collagenous sprue.Case presentationWe report a case of a 46-year-old female who was previously diagnosed as having seronegative arthritis and inflammatory bowel disease, and three years later after the initial diagnosis she was histologically confirmed to have celiac disease in association with collagenous sprue, another underlying malabsorptive disorder.ConclusionAlthough the precise relationship between celiac disease and collagenous sprue has been debated and remains controversial, it should be considered among the differential diagnoses of chronic diarrhea with progressive malabsorption.

Collagenous Sprue

Collagenous sprue is a rare form of small bowel enteropathy characterized by chronic diarrhea and progressive malabsorption with little data available on its natural history. The pathologic lesion consists of subepithelial collagen deposition associated with variable alterations in villous architecture. The small bowel biopsies of 12 cases were reviewed. Clinical details, celiac serology, and T-cell receptor gene rearrangement study results, when available, were collated. There were 8 females and 4 males (age ranged from 41 to 84 y) who presented with chronic diarrhea and weight loss. Small intestinal biopsies showed subepithelial collagen deposition with varying degrees of villous atrophy and varying numbers of intraepithelial lymphocytes. Four patients had previous biopsies showing enteropathic changes without collagen deposition. Seven cases were associated with collagenous colitis and 1 also had features of lymphocytic colitis. Three patients also had collagen deposition in gastric biopsies. One case was associated with lymphocytic gastritis. Celiac disease (CD, gluten-sensitive enteropathy) was documented in 4 patients. Five patients made a clinical improvement with combinations of a gluten-free diet and immunosuppressive therapy. Two patients died of complications of malnutrition and 1 of another illness. Clonal T-cell populations were identified in 5 of 6 cases tested. Four of these patients improved clinically after treatment but 1 has died. Collagenous sprue evolved on a background of CD in 4 cases. There was no history of CD in others and these cases may be the result of a biologic insult other than gluten sensitivity. None has developed clinical evidence of lymphoma to date.

Monitoring sputum eosinophils in mucosal inflammation and remodelling: a pilot study

Normalisation of eosinophil counts in sputum of asthmatic patients reduces eosinophilic exacerbations. However, the effect of this strategy on airway remodelling remains to be determined. We compared bronchial inflammation and collagen deposition after 2 yrs of treatment guided by either sputum eosinophils (sputum strategy, SS) or by clinical criteria (clinical strategy, CS). As a pilot study, 20 mild asthmatic patients were randomly assigned to CS or SS strategies. Bronchial biopsies were obtained when minimum treatment needed to maintain control was identified and this was continued for 2 yrs. Biopsies were immunostained for inflammatory cells, mucin 5A (MUC5A) and collagen. The mean dose of inhaled corticosteroids at the start and end of the study was similar in both SS and CS groups. Forced expiratory volume in 1 s increased in both groups at the study end. In SS, mucosal lymphocyte and eosinophil counts, but not neutrophils, were reduced at the end of the study. In CS, only activated eosinophil and neutrophil counts decreased. MUC5A staining decreased in SS but not CS. No change in collagen deposition underneath the basement membrane was observed in either strategy. Treatment strategies that normalise sputum eosinophils also reduce mucosal inflammatory cells and MUC5A expression, but do not change subepithelial collagen deposition in mild to moderate asthma.

M1189 Collagenous Sprue: Clinical Characteristics, Response to Steroids, and Prognosis

Background: Collagenous sprue (CS) is a very rare cause of severe malabsorption with an enteropathy that is characterized by villous atrophy and a distinctive band of subepithelial collagen deposition. A poor outcome has been reported historically. Aim: To describe the clinical characteristics, treatment, and prognosis in a contemporary cohort of patients with CS. Methods: We included cases with biopsy-proven CS evaluated at the Mayo Clinic Results: 15 patients (80% females) with a median age of 67 years (range, 53-83) were included. The clinical manifestations were diarrhea (100%), loss of weight (93%), and abdominal pain (14%). Hospitalizationwas required because severe diarrhea in 9 (64%) patients. Hypoalbuminemia and anemia were evident in 9 (64%) and 7 (50%) patients, respectively. Humanleukocyte antigen genes DQ2 or DQ8 were present in 12 (80%) patients (DQ2+ single dose [n=8], DQ2+ double dose [n=3], and DQ2+/DQ8+ [n=1]). Celiac antibodies were present in only 1 patient. A prior diagnosis of celiac disease was evident in 7 (47%) patients. Histologically, all cases had both the abnormal collagen deposition and some degree of villous atrophy. Aberrant (clonal) intraepithelial lymphocytes were detected in 1 (of 12) patients tested by both immunostaining and T-cell clonality analysis. Associated disorders were collagenous gastritis (n=4), collagenous colitis (n=4), small-intestine bacterial overgrowth (n=4), lymphocytic colitis (n=2), lymphocytic gastritis (n=1), autoimmune hepatitis (n=1), and hyposplenism (n=1). All patients received treatment with a combination of a strict gluten-free diet and steroids such as budesonide 9mg/day (n=12), prednisone 30-40 mg/day (n=2) and dexamethasone 8 mg/day (n=1). Parenteral nutrition was necessary in 11 (79%) patients. One patient developed enteropathy-type T-cell lymphoma during followup and received a combination of nitrogen mustard and methylprednisolone. Clinical followup after treatment was available in 12 (92%) patients (median time = 16 months; range, 172), disappearance of diarrhea was observed in 11 with complete histologic remission documented in one case. Three patients died during follow-up because of emaciation, enteropathy-type T-cell lymphoma, and aspiration pneumonia, respectively. Conclusions: We report the largest case series of CS. Treatment with a combination of gluten-free diet and steroids (especially budesonide) was useful to control symptoms in most patients; however, length of follow-up was limited so far to a few months in the majority of our patients. CS was associated with collagen deposition in other organs, autoimmune conditions, and lymphoma.

M1190 Natural History of Eosinophilic Gastroenteritis

Background: Collagenous sprue (CS) is a very rare cause of severe malabsorption with an enteropathy that is characterized by villous atrophy and a distinctive band of subepithelial collagen deposition. A poor outcome has been reported historically. Aim: To describe the clinical characteristics, treatment, and prognosis in a contemporary cohort of patients with CS. Methods: We included cases with biopsy-proven CS evaluated at the Mayo Clinic Results: 15 patients (80% females) with a median age of 67 years (range, 53-83) were included. The clinical manifestations were diarrhea (100%), loss of weight (93%), and abdominal pain (14%). Hospitalizationwas required because severe diarrhea in 9 (64%) patients. Hypoalbuminemia and anemia were evident in 9 (64%) and 7 (50%) patients, respectively. Humanleukocyte antigen genes DQ2 or DQ8 were present in 12 (80%) patients (DQ2+ single dose [n=8], DQ2+ double dose [n=3], and DQ2+/DQ8+ [n=1]). Celiac antibodies were present in only 1 patient. A prior diagnosis of celiac disease was evident in 7 (47%) patients. Histologically, all cases had both the abnormal collagen deposition and some degree of villous atrophy. Aberrant (clonal) intraepithelial lymphocytes were detected in 1 (of 12) patients tested by both immunostaining and T-cell clonality analysis. Associated disorders were collagenous gastritis (n=4), collagenous colitis (n=4), small-intestine bacterial overgrowth (n=4), lymphocytic colitis (n=2), lymphocytic gastritis (n=1), autoimmune hepatitis (n=1), and hyposplenism (n=1). All patients received treatment with a combination of a strict gluten-free diet and steroids such as budesonide 9mg/day (n=12), prednisone 30-40 mg/day (n=2) and dexamethasone 8 mg/day (n=1). Parenteral nutrition was necessary in 11 (79%) patients. One patient developed enteropathy-type T-cell lymphoma during followup and received a combination of nitrogen mustard and methylprednisolone. Clinical followup after treatment was available in 12 (92%) patients (median time = 16 months; range, 172), disappearance of diarrhea was observed in 11 with complete histologic remission documented in one case. Three patients died during follow-up because of emaciation, enteropathy-type T-cell lymphoma, and aspiration pneumonia, respectively. Conclusions: We report the largest case series of CS. Treatment with a combination of gluten-free diet and steroids (especially budesonide) was useful to control symptoms in most patients; however, length of follow-up was limited so far to a few months in the majority of our patients. CS was associated with collagen deposition in other organs, autoimmune conditions, and lymphoma.

Repeated fungal exposure leads to eosinophilia and airway remodeling in a murine model of allergic asthma (80.13)

Abstract Allergic asthma is characterized by airway hyperresponsiveness, inflammation, bronchial smooth muscle cell and goblet cell hyperplasia, and subepithelial fibrosis. Differences between human and mouse lung anatomy makes the accurate reproduction of these characteristics challenging to mimic in a mouse model. We hypothesized that repeated allergen exposure would enhance changes observed in the lungs of allergic mice, thereby closely mimicking human disease. C57BL/6 mice were sensitized and challenged with Aspergillus fumigatus antigen and live conidia via airborne delivery respectively over the course of five weeks. Changes in lung architecture, inflammation, antibody, and cytokine profiles were analyzed at days 3, 7, and 14 after the first challenge. An additional group of mice were subjected to a second fungal challenge two weeks after the first, and the same analysis was carried out. While a single challenge resulted in a rapid infiltration and egress of neutrophils at day 3, there were no neutrophils recruited after the second challenge, although eosinophils were recruited more rapidly and in higher quantities. The trichrome stains showed a striking increase in subepithelial collagen deposition and smooth muscle mass immediately following the second fungal exposure. An increase in immunoglobulin (Ig)-E, and a decrease in IgG2a were observed following the second challenge. While cytokines interleukin (IL)-4, IL-5, interferon (IFN)-γ and tumor necrosis factor (TNF)-α peaked at day 14 after the first challenge, the second challenge resulted in peak cytokine levels at day 3. Airborne fungal conidia permits a natural exposure to allergen and mimics characteristics of human asthma with increased eosinophilia, subepithelial collagen, smooth muscle mass, IgE, and cytokines. (2P20RR015566)

Chronic intranasal administration of Aspergillus fumigatus spores leads to aggravation of airway inflammation and remodelling in asthmatic rats

Epidemiological evidence indicates a close link between exposure to fungi and deterioration of asthma. However, the role of fungi as an exogenous precipitant for initiation and progression of asthma has been incompletely explored. In this study, the effects of Aspergillus fumigatus exposure on airway inflammation and remodelling in a rat model of chronic asthma were investigated. The rat model of chronic asthma was established by systemic sensitization and repeated challenge with ovalbumin (OVA). The asthmatic rats were exposed to chronic intranasal inhalation of A. fumigatus spores. Changes in airway inflammation, remodelling and BHR were measured after exposure to the fungus. Chronic inhalation of A. fumigatus spores elevated the production of T helper 2 (Th2) cytokines, increased the concentration of total serum IgE, and resulted in the recruitment of eosinophils and lymphocyte infiltration into the airways of asthmatic rats. Goblet cell hyperplasia, mucus hyperproduction and subepithelial collagen deposition were also induced by inhalation of the fungus. The remodelling changes induced by inhalation of the fungus paralleled the changes in BHR in this rat model of asthma. Chronic exposure to A. fumigatus aggravated Th2 airway inflammation, promoted airway remodelling and increased BHR in OVA-sensitized and -challenged rats.

Comparison of Acute Inflammatory and Chronic Structural Asthma-Like Responses between C57BL/6 and BALB/c Mice

Background: The interactions between airway responsiveness, structural remodelling and inflammation in allergic asthma remain poorly understood. Prolonged challenge with inhaled allergen is necessary to replicate many of the features of airway wall remodelling in mice. In both mice and humans, genetic differences can have a profound influence on allergy, inflammation, airway responsiveness and structural changes. Methods: The aim of this study was to provide a comparative analysis of allergen-induced airway changes in sensitized BALB/c and C57BL/6 mice that were exposed to inhaled allergen for 2 (‘acute’), 6 or 9 weeks (‘chronic’). Inflammation, remodelling and responsiveness were analyzed. Results: Both strains developed a Th-2-driven airway inflammation with allergen-specific IgE, airway eosinophilia and goblet cell hyperplasia upon 2 weeks of allergen inhalation. This was accompanied by a significant increase in airway smooth muscle mass and hyperresponsiveness in BALB/c but not in C57BL/6 mice. However, airway eosinophilia was more pronounced in the C57BL/6 strain. Chronic allergen exposure (6 or 9 weeks) resulted in an increase in airway smooth muscle mass as well as subepithelial collagen and fibronectin deposition in both strains. The emergence of these structural changes paralleled the disappearance of inflammation in both C57BL/6 and BALB/c mice and loss of hyperresponsiveness in the BALB/c strain. TGF-β₁was accordingly elevated in both strains. Conclusion: Airway inflammation, remodelling and hyperresponsiveness are closely intertwined processes. Genetic background influences several aspects of the acute allergic phenotype. Chronic allergen exposure induces a marked airway remodelling that parallels a decreased inflammation, which was largely comparable between the two strains.

Lymphocytic enterocolitis in systemic lupus erythematosus

Microscopic colitis (MC) is a recognized cause of chronic watery diarrhea. It is characterized by subepithelial collagen deposition or intraepithelial lymphocytic infiltration of the colonic mucosa which, however, appears grossly normal on endoscopy. The term microscopic enterocolitis is applied when MC is associated with similar microscopic affection of the ileum and/or proximal small intestine. MC is reported to be associated with a variety of autoimmune conditions. Systemic lupus erythematosus (SLE) is rarely reported in association with MC. We report a female patient with microscopic enterocolitis as one of the presenting manifestations of SLE.

C-Jun N-Terminal Kinase 1 Is Required for the Development of Pulmonary Fibrosis

Collagen deposition is observed in a diverse set of pulmonary diseases, and the unraveling of the molecular signaling pathways that facilitate collagen deposition represents an ongoing area of investigation. The stress-activated protein kinase, c-Jun N-terminal kinase 1 (JNK1), is activated by a large variety of cellular stresses and environmental insults. Recent work from our laboratory demonstrated the critical role of JNK1 in epithelial to mesenchymal transition. The goal of the present study was to examine the involvement of JNK1 in subepithelial collagen deposition in mice subjected to models of allergic airways disease and interstitial pulmonary fibrosis. Activation of JNK was slightly enhanced in lungs from mice subjected to sensitization and challenge with ovalbumin (Ova), and predominant localization of phospho-JNK was observed in the bronchial epithelium. While mice lacking JNK1 (JNK1-/- mice) displayed enhanced lung inflammation and cytokine production compared with wild-type (WT) mice, JNK1-/- mice accumulated less subepithelial collagen deposition in response to antigen, and showed decreased expression of profibrotic genes compared with WT animals. Furthermore, transforming growth factor (TGF)-beta1 content in the bronchoalveolar lavage was diminished in JNK1-/- mice compared with WT animals subjected to antigen. Finally, we demonstrated that mice lacking JNK1 were protected against TGF-beta1 and bleomycin-induced pro-fibrotic gene expression and pulmonary fibrosis. Collectively, these findings demonstrate an important requirement for JNK1 in promoting collagen deposition in multiple models of fibrosis.