Plasma microRNAs as biomarkers in hereditary angioedema.

BACKGROUND: Hereditary angioedema (HAE) is an autosomal dominant disease with variable expression. In some families with identical genetic abnormalities, the expression can range from several attacks per month to no attacks at all. It is hypothesized that post-transcriptional gene regulation accounts for the variable expression of the disease. OBJECTIVE: To identify candidate microRNAs (miRNAs) that could play a role in HAE by determining whether miRNAs are differentially expressed in patients with HAE vs non-HAE individuals and whether expression profiles are tracked with severity. METHODS: This study compared serum miRNA expression in patients with HAE vs non-HAE using RNA sequencing. Associations between miRNA expression and HAE severity were assessed in patients with mild disease (<6 attacks a year) vs severe disease (>1 attack per month). The functions of candidate miRNAs were analyzed using in silico methods. RESULTS: There were robust miRNA expression differences between patients with HAE and non-HAE controls. A cluster analysis identified subgroups of patients with HAE having unique miRNA profiles that tracked with frequency of attacks. Two miRNAs, miR-99b-5p and miR-127-3p, were differentially expressed between mild and severe HAE (adjusted P < .05). In silico analysis revealed a function of differentially expressed miRNAs in regulation of C1 esterase inhibitor, kininogen, the bradykinin B2 receptor, and adherens junction function. CONCLUSION: Candidate microRNAs were identified that could distinguish patients with and without HAE and may be used to identify phenotypes of HAE.

Prior authorization delays biologic initiation and is associated with a risk of asthma exacerbations.

Background: Biologics are effective treatments for patients with severe allergic disease. Impacts of delays in the prior authorization process on clinical outcomes has not been studied. Objective: The objective was to quantify the times for approval and filling of biologics, and whether patients were at risk of exacerbations during this time frame. Methods: The times for insurance approval and pharmacy filling of biologics (omalizumab, benralizumab, mepolizumab, dupilumab) in 80 subjects with severe asthma (n = 60) or urticaria (n = 20) from our clinic were reviewed. We compared the impact of clinical features, insurance, specialty pharmacy on fill times, and quantified exacerbations and prednisone use while awaiting biologic initiation. Results: The mean ± standard deviation (SD) time (days) from submission of a prescription to the first dose available for injection was 44.0 ± 23.2 days. This was composed of the mean ± SD time for insurance approval (21.5 ± 19.6 days) and the mean ± SD time for a specialty pharmacy to fill the medication (22.8 ± 14.1 days). There was no significant difference between the times for diagnosis (asthma versus urticaria), specific biologic, or insurance. The "buy and bill" system was faster than filling via a specialty pharmacy (mean ± SD, 7.3 ± 8.5 days versus 23.3 ± 21.3 days, respectively, p < 0.001). Clinical features of patients with fast versus slow approval times was not significantly different. The subjects with asthma were at high risk of exacerbations and need for prednisone while awaiting initiation of the biologics; 28 of 59 patients (47%) required prednisone, with an mean cumulative dose of 483.2 ± 273.7 mg per person. Conclusion: The prior authorization process for biologics was slow, and the subjects were at high risk of exacerbations during this time. The system needs to be improved to expedite approval and initiation of these medications.

miR-155 Modulates Cockroach Allergen- and Oxidative Stress-Induced Cyclooxygenase-2 in Asthma.

Exposure to cockroach allergen is a strong risk factor for developing asthma. Asthma has been associated with allergen-induced airway epithelial damage and heightened oxidant stress. In this study, we investigated cockroach allergen-induced oxidative stress in airway epithelium and its underlying mechanisms. We found that cockroach extract (CRE) could induce reactive oxygen species (ROS) production, particularly mitochondrial-derived ROS, in human bronchial epithelial cells. We then used the RT2 Profiler PCR array and identified that cyclooxygenase-2 (COX-2) was the most significantly upregulated gene related to CRE-induced oxidative stress. miR-155, predicted to target COX-2, was increased in CRE-treated human bronchial epithelial cells, and was showed to regulate COX-2 expression. Moreover, miR-155 can bind COX-2, induce COX-2 reporter activity, and maintain mRNA stability. Furthermore, CRE-treated miR-155-/- mice showed reduced levels of ROS and COX-2 expression in lung tissues and PGE2 in bronchoalveolar lavage fluid compared with wild-type mice. These miR-155-/- mice also showed reduced lung inflammation and Th2/Th17 cytokines. In contrast, when miR-155-/- mice were transfected with adeno-associated virus carrying miR-155, the phenotypic changes in CRE-treated miR-155-/- mice were remarkably reversed, including ROS, COX-2 expression, lung inflammation, and Th2/Th17 cytokines. Importantly, plasma miR-155 levels were elevated in severe asthmatics when compared with nonasthmatics or mild-to-moderate asthmatics. These increased plasma miR-155 levels were also observed in asthmatics with cockroach allergy compared with those without cockroach allergy. Collectively, these findings suggest that COX-2 is a major gene related to cockroach allergen-induced oxidative stress and highlight a novel role of miR-155 in regulating the ROS-COX-2 axis in asthma.

Isolation and profiling of plasma microRNAs: Biomarkers for asthma and allergic rhinitis.

Chronic inflammatory diseases can be particularly challenging to diagnose and characterize, as inflammatory changes in tissue may not be present in blood. There is a crucial need to develop non-invasive biomarkers that would be useful in diagnosing disease and selecting medical therapies. For example, there are no blood tests to diagnose asthma, a common inflammatory lung disease. MicroRNA (miRNA) expression profiling in blood is emerging as a potentially sensitive and useful biomarker of many diseases. In particular, we have characterized a cost-effective PCR-based array technology to measure and profile circulating miRNAs in the plasma of patients with allergic rhinitis and asthma. Here, we describe the methods to isolate, quantify, and analyze miRNAs in the plasma of human subjects as well as ways to determine their diagnostic utility.

Mannose receptor modulates macrophage polarization and allergic inflammation through miR-511-3p.

BACKGROUND: Mannose receptor (MRC1/CD206) has been suggested to mediate allergic sensitization and asthma to multiple glycoallergens, including cockroach allergens. OBJECTIVE: We sought to determine the existence of a protective mechanism through which MRC1 limits allergic inflammation through its intronic miR-511-3p. METHODS: We examined MRC1-mediated cockroach allergen uptake by lung macrophages and lung inflammation using C57BL/6 wild-type (WT) and Mrc1-/- mice. The role of miR-511-3p in macrophage polarization and cockroach allergen-induced lung inflammation in mice transfected with adeno-associated virus (AAV)-miR-511-3p (AAV-cytomegalovirus-miR-511-3p-enhanced green fluorescent protein) was analyzed. Gene profiling of macrophages with or without miR-511-3p overexpression was also performed. RESULTS: Mrc1-/- lung macrophages showed a significant reduction in cockroach allergen uptake compared with WT mice, and Mrc1-/- mice had an exacerbated lung inflammation with increased levels of cockroach allergen-specific IgE and TH2/TH17 cytokines in a cockroach allergen-induced mouse model compared with WT mice. Macrophages from Mrc1-/- mice showed significantly reduced levels of miR-511-3 and an M1 phenotype, whereas overexpression of miR-511-3p rendered macrophages to exhibit a M2 phenotype. Furthermore, mice transfected with AAV-miR-511-3p showed a significant reduction in cockroach allergen-induced inflammation. Profiling of macrophages with or without miR-511-3p overexpression identified 729 differentially expressed genes, wherein expression of prostaglandin D2 synthase (Ptgds) and its product PGD2 were significantly downregulated by miR-511-3p. Ptgds showed a robust binding to miR-511-3p, which might contribute to the protective effect of miR-511-3p. Plasma levels of miR-511-3p were significantly lower in human asthmatic patients compared with nonasthmatic subjects. CONCLUSION: These studies support a critical but previously unrecognized role of MRC1 and miR-511-3p in protection against allergen-induced lung inflammation.

Circulating microRNAs as biomarkers in patients with allergic rhinitis and asthma.

BACKGROUND: MicroRNAs (miRNAs) are emerging as important regulatory molecules that might be involved in the pathogenesis of various diseases. Circulating miRNAs might be noninvasive biomarkers to diagnose and characterize asthma and allergic rhinitis (AR). OBJECTIVE: We sought to determine whether miRNAs are differentially expressed in the blood of asthmatic patients compared with those in the blood of nonasthmatic patients with AR and nonallergic nonasthmatic subjects. Furthermore, we sought to establish whether miRNAs could be used to characterize or subtype asthmatic patients. METHODS: Expression of plasma miRNAs was measured by using real-time quantitative PCR in 35 asthmatic patients, 25 nonasthmatic patients with AR, and 19 nonallergic nonasthmatic subjects. Differentially expressed miRNAs were identified by using Kruskal-Wallis 1-way ANOVA with Bonferroni P value adjustment to correct for multiple comparisons. A random forest classification algorithm combined with a leave-one-out cross-validation approach was implemented to assess the predictive capacities of the profiled miRNAs. RESULTS: We identified 30 miRNAs that were differentially expressed among healthy, allergic, and asthmatic subjects. These miRNAs fit into 5 different expression pattern groups. Among asthmatic patients, miRNA expression profiles identified 2 subtypes that differed by high or low peripheral eosinophil levels. Circulating miR-125b, miR-16, miR-299-5p, miR-126, miR-206, and miR-133b levels were most predictive of allergic and asthmatic status. CONCLUSIONS: Subsets of circulating miRNAs are uniquely expressed in patients with AR and asthmatic patients and have potential for use as noninvasive biomarkers to diagnose and characterize these diseases.

Regulation of UGT2B Expression and Activity by miR-216b-5p in Liver Cancer Cell Lines.

The UDP-glucuronosyltransferase (UGT) 2B enzymes are important in the detoxification of a variety of endogenous and exogenous compounds, including many hormones, drugs, and carcinogens. Identifying novel mechanisms governing their expression is important in understanding patient-specific response to drugs and cancer risk factors. In silico prediction algorithm programs were used to screen for microRNAs (miRNAs) as potential regulators of UGT2B enzymes, with miR-216b-5p identified as a potential candidate. Luciferase data suggested the presence of a functional miR-216b-5p binding motif within the 3' untranslated regions of UGTs 2B7, 2B4, and 2B10. Overexpression of miR-216b-5p mimics significantly repressed UGT2B7 (P < 0.001) and UGT2B10 (P = 0.0018) mRNA levels in HuH-7 cells and UGT2B4 (P < 0.001) and UGT2B10 (P = 0.018) mRNA in Hep3B cells. UGT2B7 protein levels were repressed in both HuH-7 and Hep3B cells in the presence of increasing miR-216b-5p concentrations, corresponding with significant (P < 0.001 and P = 0.011, respectively) decreases in glucuronidation activity against the UGT2B7-specific substrate epirubicin. Inhibition of endogenous miR-216b-5p levels significantly increased UGT2B7 mRNA levels in HuH-7 (P = 0.021) and Hep3B (P = 0.0068) cells, and increased epirubicin glucuronidation by 85% (P = 0.057) and 50% (P = 0.012) for HuH-7 and Hep3B cells, respectively. UGT2B4 activity against codeine and UGT2B10 activity against nicotine were significantly decreased in both HuH-7 and Hep3B cells (P < 0.001 and P = 0.0048, and P = 0.017 and P = 0.043, respectively) after overexpression of miR-216b-5p mimic. This is the first evidence that miRNAs regulate UGT 2B7, 2B4, and 2B10 expression, and that miR-216b-5p regulation of UGT2B proteins may be important in regulating the metabolism of UGT2B substrates.

Post-transcriptional regulation of meprin α by the RNA-binding proteins Hu antigen R (HuR) and tristetraprolin (TTP).

Meprins are multimeric proteases that are implicated in inflammatory bowel disease by both genetic association studies and functional studies in knock-out mice. Patients with inflammatory bowel disease show decreased colonic expression of meprin α, although regulation of expression, particularly under inflammatory stimuli, has not been studied. The studies herein demonstrate that the human meprin α transcript is bound and stabilized by Hu antigen R at baseline, and that treatment with the inflammatory stimulus phorbol 12-myristate 13-acetate downregulates meprin α expression by inducing tristetraprolin. The enhanced binding of tristetraprolin to the MEP1A 3'-UTR results in destabilization of the transcript and occurs at a discrete site from Hu antigen R. This is the first report to describe a mechanism for post-transcriptional regulation of meprin α and will help clarify the role of meprins in the inflammatory response and disease.

High-grade fever and pancytopenia in an adult patient with common variable immune deficiency.

Fever of unknown origin in patients with common variable immune deficiency (CVID) can be caused by variety of infectious, autoimmune, or malignancy-related etiologies. We present a 52-year-old man with history of CVID, who presented with 3 weeks of persistent high-grade fevers. During admission, he developed severe pancytopenia with shock and multiorgan failure. An extensive workup was performed for typical and atypical infections, autoimmune pathologies, and malignancy. His peripheral blood smear showed marked anisocytosis and poikilocytosis with elevated atypical lymphocytes. Flow cytometry showed markedly elevated CD8 counts, with abnormal CD4/CD8 ratio. Monospot test was negative but real-time polymerase chain reaction showed high Epstein-Barr virus load. Initial clinical suspicion was high for bacterial infections including pneumonia and acute sinusitis complicated by bacteremia and sepsis. Hematologic malignancy was also high on the differentials because of presence of rapidly progressive pancytopenia. The final diagnosis in this case illustrates a rare but potentially fatal disease that can present in CVID patients with persistent fevers and pancytopenia and can be refractory to standard treatment regimen. Because allergy and immunology physicians commonly treat CVID patients, they should be aware of this disease condition including pathophysiology, clinical presentation, laboratory workup, and treatment options.

Identification of biologic-responsive phenotypes in elderly people with eosinophilic asthma.

Background: Asthma in the elderly is not as well studied as in younger age groups. Age-related immunosenescence may result in diminished TH2 inflammation, which raises a question about whether asthma in elderly patients responds well to anti-TH2 asthma biologics. Objective: We sought to determine whether asthma in elderly people has different TH2 biomarkers and clinical features compared to nonelderly people, and if disease in the 2 age groups responds differently to anti-TH2 biologics. We also aimed to identify treatment-responsive phenotypes with clinical and biomarker features that could be used to predict best response to biologics. Methods: A retrospective chart review was conducted for 56 patients (30 elderly [age ≥62 years] and 26 nonelderly [ages 18-59 years] subjects) with severe asthma treated with dupilumab or benralizumab. Differences in baseline characteristics and response to treatment were analyzed. A hierarchical cluster analysis was also performed to identify treatment-responsive phenotypes. Significance threshold was P = .05 for all analyses. Results: Baseline characteristics and TH2 biomarkers (blood eosinophil level, total IgE, aeroallergen sensitivity) were similar between elderly and nonelderly subjects. The disease in both groups responded well to biologics (improvement in ACT scores, decreased exacerbations, decreased need for prednisone), but no significant response difference was found based on age groups. Cluster analysis identified 3 phenotypes, as follows: cluster 1, youngest age, moderate eosinophil levels, lowest total IgE, few environmental allergies, and least response to biologics; cluster 2, intermediate age, lowest eosinophil level, highest IgE level, many environmental allergies, and an intermediate response to biologics; and cluster 3, oldest ages, highest eosinophil levels, high total IgE, few environmental allergies, and best response to biologics. These results confirm trends seen in another study utilizing cluster analyses showing that subjects with highest levels of IgE and eosinophils responded better to biologic treatment for asthma. Conclusion: Elderly people with asthma should be considered for biologic therapy no differently than younger people. There may be subgroups of patients with different biologic responses based on age, allergenicity, IgE, and eosinophil levels that could be used to predict treatment response.

Penicillin Allergy: Mechanisms, Diagnosis, and Management.

Allergy to penicillin can occur via any of the 4 types of Gel-Coombs hypersensitivity reactions, producing distinct clinical histories and physical examination findings. Treatments include penicillin discontinuation, and depending on the type of reaction, epinephrine, antihistamines, and/or glucocorticoids. Most beta-lactams may be safely used in penicillin-allergic patients, with the possible exception of first-generation and second-generation cephalosporins. Penicillin testing includes skin testing, patch testing, and graded challenge. The selection of the type of testing depends on the clinical setting, equipment availability, and type of hypersensitivity reaction. Desensitization may be used in some cases where treatment with penicillins is essential.

Chemokine transcripts as targets of the RNA-binding protein HuR in human airway epithelium.

HuR is a regulator of mRNA turnover or translation of inflammatory genes through binding to adenylate-uridylate-rich elements and related motifs present in the 3'untranslated region (UTR) of mRNAs. We postulate that HuR critically regulates the epithelial response by associating with multiple ARE-bearing, functionally related inflammatory transcripts. We aimed to identify HuR targets in the human airway epithelial cell line BEAS-2B challenged with TNF-α plus IFN-γ, a strong stimulus for inflammatory epithelial responses. Ribonucleoprotein complexes from resting and cytokine-treated cells were immunoprecipitated using anti-HuR and isotype-control Ab, and eluted mRNAs were reverse-transcribed and hybridized to an inflammatory-focused gene array. The chemokines CCL2, CCL8, CXCL1, and CXCL2 ranked highest among 27 signaling and inflammatory genes significantly enriched in the HuR RNP-IP from stimulated cells over the control immunoprecipitation. Among these, 20 displayed published HuR binding motifs. Association of HuR with the four endogenous chemokine mRNAs was validated by single-gene ribonucleoprotein-immunoprecipitation and shown to be 3'UTR-dependent by biotin pull-down assay. Cytokine treatment increased mRNA stability only for CCL2 and CCL8, and transient silencing and overexpression of HuR affected only CCL2 and CCL8 expression in primary and transformed epithelial cells. Cytokine-induced CCL2 mRNA was predominantly cytoplasmic. Conversely, CXCL1 mRNA remained mostly nuclear and unaffected, as CXCL2, by changes in HuR levels. Increase in cytoplasmic HuR and HuR target expression partially relied on the inhibition of AMP-dependent kinase, a negative regulator of HuR nucleocytoplasmic shuttling. HuR-mediated regulation in airway epithelium appears broader than previously appreciated, coordinating numerous inflammatory genes through multiple posttranscriptional mechanisms.

The human glucocorticoid receptor as an RNA-binding protein: global analysis of glucocorticoid receptor-associated transcripts and identification of a target RNA motif.

Posttranscriptional regulation is emerging as a key factor in glucocorticoid (GC)-mediated gene regulation. We investigated the role of the human GC receptor (GR) as an RNA-binding protein and its effect on mRNA turnover in human airway epithelial cells. Cell treatment with the potent GC budesonide accelerated the decay of CCL2 mRNA (t(1/2) = 8 ± 1 min versus 62 ± 17 min in DMSO-treated cells) and CCL7 mRNA (t(1/2) = 15 ± 4 min versus 114 ± 37 min), but not that of CCL5 mRNA (t(1/2)=231 ± 8 min versus 266 ± 5 min) in the BEAS-2B cell line. This effect was inhibited by preincubation with an anti-GR Ab, indicating that GR itself plays a role in the turnover of these transcripts. Coimmunoprecipitation and biotin pulldown experiments showed that GR associates with CCL2 and CCL7 mRNAs, but not CCL5 mRNA. These methods confirmed CCL2 mRNA targeting by GR in human primary airway epithelial cells. Association of the GR was localized to the 5' untranslated region of CCL2 mRNA and further mapped to nt 44-60. The collection of transcripts associated with GR, identified by immunoprecipitation of GR-mRNA complexes followed by microarray analysis, revealed 479 transcripts that associated with GR. Computational analysis of the primary sequence and secondary structures of these transcripts yielded a GC-rich motif, which was shown to bind to GR in vitro. This motif was used to predict binding of GR to an additional 7889 transcripts. These results indicate that cytoplasmic GR interacts with a subset of mRNA through specific sequences and can regulate turnover rates, suggesting a novel posttranscriptional role for GR as an RNA-binding protein.

The Myc 3' Wnt responsive element regulates neutrophil recruitment after acute colonic injury in mice.

BACKGROUND: The Wnt/ß-catenin pathway regulates intestinal development, homeostasis, and regeneration after injury. Wnt/ß-catenin signaling drives intestinal proliferation by activating expression of the c-Myc proto-oncogene (Myc) through the Myc 3' Wnt responsive DNA element (Myc 3' WRE). In a previous study, we found that deletion of the Myc 3' WRE in mice caused increased MYC expression and increased cellular proliferation in the colon. When damaged by dextran sodium sulfate (DSS), the increased proliferative capacity of Myc 3' WRE(-/-) colonocytes resulted in a more rapid recovery compared with wild-type (WT) mice. In that study, we did not examine involvement of the immune system in colonic regeneration. PURPOSE: To characterize the innate immune response in Myc 3' WRE(-/-) and WT mice during and after DSS-induced colonic injury. METHODS: Mice were fed 2.5 % DSS in their drinking water for five days to induce colonic damage and were then returned to normal water for two or four days to recover. Colonic sections were prepared and neutrophils and macrophages were analyzed by immunohistochemistry. Cytokine and chemokine levels were analyzed by probing a cytokine array with colonic lysates. RESULTS: In comparison with WT mice, there was enhanced leukocyte infiltration into the colonic mucosal and submucosal layers of Myc 3' WRE(-/-) mice after DSS damage. Levels of activated neutrophils were substantially increased in damaged Myc 3' WRE(-/-) colons as were levels of the neutrophil chemoattractants C5/C5a, CXCL1, and CXCL2. CONCLUSION: The Myc 3' WRE regulates neutrophil infiltration into DSS-damaged colons.

Penicillin Allergy: Mechanisms, Diagnosis, and Management.

Allergy to penicillin can occur via any of the 4 types of Gel-Coombs hypersensitivity reactions, producing distinct clinical histories and physical examination findings. Treatments include penicillin discontinuation, and depending on the type of reaction, epinephrine, antihistamines, and/or glucocorticoids. Most beta-lactams may be safely used in penicillin-allergic patients, with the possible exception of first-generation and second-generation cephalosporins. Penicillin testing includes skin testing, patch testing, and graded challenge. The selection of the type of testing depends on the clinical setting, equipment availability, and type of hypersensitivity reaction. Desensitization may be used in some cases where treatment with penicillins is essential.

Physician approaches to beta-lactam use in patients with penicillin hypersensitivity.

Beta-lactam antibiotics are widely used, but hypersensitivity reactions are common and difficult to manage. This study was designed to identify lack of knowledge regarding the safe use of alternative beta-lactams in penicillin-allergic patients and assess management differences between allergists and nonallergists. An electronic physician survey was sent to 623 providers in allergy, internal medicine, pediatrics, and family medicine, querying beta-lactam use in patients with a history of penicillin allergy. A total of 110 (17.7%) surveys were completed. For patients with a prior maculopapular rash to penicillin, most providers were uncomfortable prescribing penicillins again, although they would use other beta-lactams. In patients with an exfoliative dermatitis to penicillin, 46% of responders would not prescribe any beta-lactam again. For patients with a positive skin test to penicillin, only 45.1% of nonallergists were comfortable prescribing monobactams versus 62.5% of allergists; 30.3% of all responders would give a carbapenem. In patients with urticaria to penicillin, pediatricians were the most comfortable prescribing third- or fourth-generation cephalosporins. Providers (both allergists and nonallergists) were unfamiliar with the safety of prescribing penicillin in patients with history of maculopapular rash, the safety of monobactams, and low cross-reactivity with carbapenems in penicillin-allergic individuals. Nonallergists were also unfamiliar with the usefulness of penicillin skin testing. Improved education is needed to address these areas. Additionally, we found variability in responses regarding exfoliative dermatitis and comfort prescribing cephalosporins in patients with suspected IgE-mediated drug allergy to penicillin, highlighting the need for additional research in these areas.

A challenging diagnosis of alpha-1-antitrypsin deficiency: identification of a patient with a novel F/Null phenotype.

Alpha-1-antitrypsin (A1AT) deficiency is a genetic disease characterized by low levels and/or function of A1AT protein. A1AT deficiency can result in the development of COPD, liver disease, and certain skin conditions. The disease can be diagnosed by demonstrating a low level of A1AT protein and genotype screening for S and Z mutations, which are the most common. However, there are many genetic variants in A1AT deficiency, and this screening may miss rarer cases, such as those caused by dysfunctional protein. We identified a patient with a previously unreported F/null phenotype that was missed by routine screening. This case highlights the wide variation in possible mutations, limitations in diagnostics, and the importance of combining clinical suspicion with measurement of protein levels, phenotypic analysis, and in appropriate cases expanded genetic analysis.

miR-511-3p protects against cockroach allergen-induced lung inflammation by antagonizing CCL2.

miR-511-3p, encoded by CD206/Mrc1, was demonstrated to reduce allergic inflammation and promote alternative (M2) macrophage polarization. Here, we sought to elucidate the fundamental mechanism by which miR-511-3p attenuates allergic inflammation and promotes macrophage polarization. Compared with WT mice, the allergen-challenged Mrc1-/- mice showed increased airway hyperresponsiveness (AHR) and inflammation. However, this increased AHR and inflammation were significantly attenuated when these mice were pretransduced with adeno-associated virus-miR-511-3p (AAV-miR-511-3p). Gene expression profiling of macrophages identified Ccl2 as one of the major genes that was highly expressed in M2 macrophages but antagonized by miR-511-3p. The interaction between miR-511-3p and Ccl2 was confirmed by in silico analysis and mRNA-miR pulldown assay. Further evidence for the inhibition of Ccl2 by miR-511-3p was given by reduced levels of Ccl2 in supernatants of miR-511-3p-transduced macrophages and in bronchoalveolar lavage fluids of AAV-miR-511-3p-infected Mrc1-/- mice. Mechanistically, we demonstrated that Ccl2 promotes M1 macrophage polarization by activating RhoA signaling through Ccr2. The interaction between Ccr2 and RhoA was also supported by coimmunoprecipitation assay. Importantly, inhibition of RhoA signaling suppressed cockroach allergen-induced AHR and lung inflammation. These findings suggest a potentially novel mechanism by which miR-511-3p regulates allergic inflammation and macrophage polarization by targeting Ccl2 and its downstream Ccr2/RhoA axis.