Synthesis, Photophysical Properties, Theoretical Studies, and Living Cancer Cell Imaging Applications of New 7-(Diethylamino)quinolone Chalcones.

In this article, three unsymmetrical 7-(diethylamino)quinolone chalcones with D-π-A-D and D-π-A-π-D type push-pull molecular arrangements were synthesized via a Claisen-Schmidt reaction. Using 7-(diethylamino)quinolone and vanillin as electron donor (D) moieties, these were linked together through the α,ß-unsaturated carbonyl system acting as a linker and an electron acceptor (A). The photophysical properties were studied, revealing significant Stokes shifts and strong solvatofluorochromism caused by the ICT and TICT behavior produced by the push-pull effect. Moreover, quenching caused by the population of the TICT state in THF-H2O mixtures was observed, and the emission in the solid state evidenced a red shift compared to the emission in solution. These findings were corroborated by density functional theory (DFT) calculations employing the wb97xd/6-311G(d,p) method. The cytotoxic activity of the synthesized compounds was assessed on BHK-21, PC3, and LNCaP cell lines, revealing moderate activity across all compounds. Notably, compound 5b exhibited the highest activity against LNCaP cells, with an LC50 value of 10.89 µM. Furthermore, the compounds were evaluated for their potential as imaging agents in living prostate cells. The results demonstrated their favorable cell permeability and strong emission at 488 nm, positioning them as promising candidates for cancer cell imaging applications.

Exploring the secrets of virus entry: the first respiratory syncytial virus carrying beta lactamase.

Background: Respiratory Syncytial Virus (RSV) presents a significant health threat, especially to young children. In-depth understanding of RSV entry mechanisms is essential for effective antiviral development. This study introduces an innovative RSV variant, featuring the fusion of the beta-lactamase (BlaM) enzyme with the RSV-P phosphoprotein, providing a versatile tool for dissecting viral entry dynamics. Methods: Using the AlphaFold2 algorithm, we modeled the tertiary structure of the P-BlaM chimera, revealing structural similarities with both RSV-P and BlaM. Functional assessments, utilizing flow cytometry, quantified beta-lactamase activity and GFP expression in infected bronchial epithelial cells. Western blot analysis confirmed the integrity of P-BlaM within virions. Results: The modeled P-BlaM chimera exhibited structural parallels with RSV-P and BlaM. Functional assays demonstrated robust beta-lactamase activity in recombinant virions, confirming successful P-BlaM incorporation as a structural protein. Quercetin, known for its antiviral properties, impeded viral entry by affecting virion fusion. Additionally, Ulixertinib, an ERK-1/2 inhibitor, significantly curtailed viral entry, implicating ERK-1/2 pathway signaling. Conclusions: Our engineered RSV-P-BlaM chimera emerges as a valuable tool, illuminating RSV entry mechanisms. Structural and functional analyses unveil potential therapeutic targets. Quercetin and Ulixertinib, identified as distinct stage inhibitors, show promise for targeted antiviral strategies. Time-of-addition assays pinpoint quercetin's specific interference stage, advancing our comprehension of RSV entry and guiding future antiviral developments.

Respiratory syncytial virus entry mechanism in host cells: A general overview.

Respiratory syncytial virus (RSV) is a virus that causes acute respiratory infections in neonates and older adults. To infect host cells, the attachment glycoprotein (G) interacts with a cell surface receptor. This interaction determines the specific cell types that are susceptible to infection. RSV possesses a type I fusion protein F. Type I fusion proteins are metastable when rearrangement of the prefusion F occurs; the fusion peptide is exposed transforming the protein into postfusion form. The transition between the prefusion form and its postfusion form facilitates the viral envelope and the host cell membrane to fuse, enabling the virus to enter the host cell. Understanding the entry mechanism employed by RSV is crucial for developing effective antiviral therapies. In this review, we will discuss the various types of viral fusion proteins and explore the potential entry mechanisms utilized by RSV. A deeper understanding of these mechanisms will provide valuable insights for the development of novel approaches to treat RSV infections.

Epigenetic Modulators as Treatment Alternative to Diverse Types of Cancer.

DNA is packaged in an octamer of histones, forming chromatin, a complex of DNA and proteins. The structural matrix of a chromosome, chromatin and its changes are now regarded as important factors in controlling gene expression, which has sparked a lot of interest in understanding genetic pathways governing various diseases, including cancer. DNA methylation in the CpG dinucleotide as a transcriptional silencing mechanism, post-translational histone modifications such as acetylation, methylation, and others that affect chromatin structure, ATP-dependent chromatin remodelling, and miRNA-mediated gene silencing are all found to be important in various types of cancer. In this review, we analyze the main alterations in gene expression, epigenetic modification patterns in cancer cells, the main modulators and inhibitors of each epigenetic mechanism, and the molecular evolution of the most representative inhibitors, all of which point to a promising future for HAT, HDAC, non-glycoside DNMT inhibitors, and domain inhibitors.

A new pipeline for structural characterization and classification of RNA-Seq microbiome data.

BACKGROUND: High-throughput sequencing enables the analysis of the composition of numerous biological systems, such as microbial communities. The identification of dependencies within these systems requires the analysis and assimilation of the underlying interaction patterns between all the variables that make up that system. However, this task poses a challenge when considering the compositional nature of the data coming from DNA-sequencing experiments because traditional interaction metrics (e.g., correlation) produce unreliable results when analyzing relative fractions instead of absolute abundances. The compositionality-associated challenges extend to the classification task, as it usually involves the characterization of the interactions between the principal descriptive variables of the datasets. The classification of new samples/patients into binary categories corresponding to dissimilar biological settings or phenotypes (e.g., control and cases) could help researchers in the development of treatments/drugs. RESULTS: Here, we develop and exemplify a new approach, applicable to compositional data, for the classification of new samples into two groups with different biological settings. We propose a new metric to characterize and quantify the overall correlation structure deviation between these groups and a technique for dimensionality reduction to facilitate graphical representation. We conduct simulation experiments with synthetic data to assess the proposed method's classification accuracy. Moreover, we illustrate the performance of the proposed approach using Operational Taxonomic Unit (OTU) count tables obtained through 16S rRNA gene sequencing data from two microbiota experiments. Also, compare our method's performance with that of two state-of-the-art methods. CONCLUSIONS: Simulation experiments show that our method achieves a classification accuracy equal to or greater than 98% when using synthetic data. Finally, our method outperforms the other classification methods with real datasets from gene sequencing experiments.

Importance of Virus Characteristics in Respiratory Syncytial Virus-Induced Disease.

Severe lower respiratory tract infection in infants and young children is most frequently caused by respiratory syncytial virus (RSV). RSV infects the smallest airways, making breathing difficult and in some infants requiring medical support. Severity is affected by viral dose, infant age, virus genotype, and effectiveness of the innate/adaptive immune responses. Severe disease correlates with later wheezing and asthma in some children. The adaptive immune response is protective but wanes after each infection, likely due to the ability of the RSV NS1/NS2 proteins to inhibit the innate immune response. Several vaccine approaches and candidates are currently in clinical trials.

Split and Merge Watershed: a two-step method for cell segmentation in fluorescence microscopy images.

The development of advanced techniques in medical imaging has allowed scanning of the human body to microscopic levels, making research on cell behavior more complex and more in-depth. Recent studies have focused on cellular heterogeneity since cell-to-cell differences are always present in the cell population and this variability contains valuable information. However, identifying each cell is not an easy task because, in the images acquired from the microscope, there are clusters of cells that are touching one another. Therefore, the segmentation stage is a problem of considerable difficulty in cell image processing. Although several methods for cell segmentation are described in the literature, they have drawbacks in terms of over-segmentation, under-segmentation or misidentification. Consequently, our main motivation in studying cell segmentation was to develop a new method to achieve a good tradeoff between accurately identifying all relevant elements and not inserting segmentation artifacts. This article presents a new method for cell segmentation in fluorescence microscopy images. The proposed approach combines the well-known Marker-Controlled Watershed algorithm (MC-Watershed) with a new, two-step method based on Watershed, Split and Merge Watershed (SM-Watershed): in the first step, or split phase, the algorithm identifies the clusters using inherent characteristics of the cell, such as size and convexity, and separates them using watershed. In the second step, or the merge stage, it identifies the over-segmented regions using proper features of the cells and eliminates the divisions. Before applying our two-step method, the input image is first preprocessed, and the MC-Watershed algorithm is used to generate an initial segmented image. However, this initial result may not be suitable for subsequent tasks, such as cell count or feature extraction, because not all cells are separated, and some cells may be mistakenly confused with the background. Thus, our proposal corrects this issue with its two-step process, reaching a high performance, a suitable tradeoff between over-segmentation and under-segmentation and preserving the shape of the cell, without the need of any labeled data or relying on machine learning processes. The latter is advantageous over state-of-the-art techniques that in order to achieve similar results require labeled data, which may not be available for all of the domains. Two cell datasets were used to validate this approach, and the results were compared with other methods in the literature, using traditional metrics and quality visual assessment. We obtained 90% of average visual accuracy and an F-index higher than 80%. This proposal outperforms other techniques for cell separation, achieving an acceptable balance between over-segmentation and under-segmentation, which makes it suitable for several applications in cell identification, such as virus infection analysis, high-content cell screening, drug discovery, and morphometry.

Gut microbiota components are associated with fixed airway obstruction in asthmatic patients living in the tropics.

Microbiome composition has been associated to several inflammatory diseases, including asthma. There are few studies exploring the relationships of gut microbiota with airway obstruction pheonotypes in adult asthma, especially those living in the tropics. We sought to evaluate the relationships of gut microbiota with the airway obstruction and other variables of interest in asthmatic patients living in the tropics according to three phenotypes: No Airway Obstruction (NAO), Reversible Airway Obstruction (RAO) or Fixed Airway Obstruction (FAO). We found that Streptococcaceae:Streptococcus and Enterobacteriaceae:Escherichia-Shigella consistently discriminated asthmatic individuals suffering FAO from NAO or RAO, plus Veillonellaceae:Megasphaera when comparing FAO and RAO (p < 0.05; FDR < 0.05). In the FAO, the network showing the genus relations was less complex and interconnected. Several Rumminococcaceae, Lachnospiraceae and Clostridiales were enriched in patients with low specific IgE levels to mites and Ascaris. All patients shared a common exposure framework; control medication usage and smoking habit were uncommon and equally distributed between them. In conclusion, in this tropical asthmatic population, components of human gut microbiota are associated with the presence of a FAO phenotype and lower specific IgE response to mites and Ascaris.

A Lachnospiraceae-dominated bacterial signature in the fecal microbiota of HIV-infected individuals from Colombia, South America.

HIV infection has a tremendous impact on the immune system's proper functioning. The mucosa-associated lymphoid tissue (MALT) is significantly disarrayed during HIV infection. Compositional changes in the gut microbiota might contribute to the mucosal barrier disruption, and consequently to microbial translocation. We performed an observational, cross-sectional study aimed at evaluating changes in the fecal microbiota of HIV-infected individuals from Colombia. We analyzed the fecal microbiota of 37 individuals via 16S rRNA gene sequencing; 25 HIV-infected patients and 12 control (non-infected) individuals, which were similar in body mass index, age, gender balance and socioeconomic status. To the best of our knowledge, no such studies have been conducted in Latin American countries. Given its compositional nature, microbiota data were normalized and transformed using Aitchison's Centered Log-Ratio. Overall, a change in the network structure in HIV-infected patients was revealed by using the SPIEC-EASI MB tool. Genera such as Blautia, Dorea, Yersinia, Escherichia-Shigella complex, Staphylococcus, and Bacteroides were highly relevant in HIV-infected individuals. Differential abundance analysis by both sparse Partial Least Square-Discriminant Analysis and Random Forest identified a greater abundance of Lachnospiraceae-OTU69, Blautia, Dorea, Roseburia, and Erysipelotrichaceae in HIV-infected individuals. We show here, for the first time, a predominantly Lachnospiraceae-based signature in HIV-infected individuals.

Characterization of treatment failure in HIV positive patients in the Colombian Caribbean region / Caracterización del fracaso terapéutico en pacientes VIH positivos en la región del Caribe Colombiano

Background: Treatment failure in patients receiving antiretroviral therapy against human immunodeficiency virus (HIV) is always a concern. Objective: To examine the correlates associated with treatment failure in patients living in the Colombian Caribbean city of Barranquilla, an aspect that was poorly studied in this region. Methods: Treatment failure (TF) was evaluated in a cross-sectional study from virological, immunological and clinical standpoints. Results: It was established that 29.5% of patients under highly active antiretroviral therapy (ART) could be considered in TF. Among those, virological failure was most frequent (20.9%), followed by immunological- (14.0%) and clinical failure (4.7%). In patients showing lack of adherence to the treatment, the likelihood of suffering from treatment- and virogical-failure were respectively increased by 6.67-fold and 12.19-fold, compared with patients showing good adherence. Although there was no statistically significant association, TF tended to be more frequent in young adults, in patients with low income and, low level of education. When ART regimens were compared, there was no apparent difference in TF between regimens based on non-nucleoside reverse transcriptase inhibitors and those based on protease inhibitors. This is very important in the context of recent ART strategies, such as early-initiated ART, aimed at achieving long-term infection control. Conclusions: Is confirmed the importance of treatment adherence to avoid TF and further highlights the importance of educating HIV-infected patients in all parts of the world, especially those individuals with a lower socio-economic status.

Antecedentes: El fracaso terapéutico (FT) en pacientes que están recibiendo terapia antirretroviral contra el Virus de la Inmunodeficiencia Humana (VIH) ha sido siempre preocupante. Objetivo: Examinar las variables asociadas con el FT, un problema que ha sido pobremente estudiado en la región, en pacientes que habitan en Barranquilla, ciudad del Caribe colombiano. Métodos: El FT fue evaluado en un estudio transversal desde los puntos de vista virológico, inmunológico y clínico. Resultados: Se determinó que el 29.5% de los pacientes bajo terapia antirretroviral (TAR) de gran actividad podría considerase en FT. El fracaso virológico fue el más frecuente (20.9%), seguido por el inmunológico (14.0%) y el clínico (4.7%). En pacientes que mostraron falta de adherencia al tratamiento, las posibilidades de presentar un FT y virológico fue mayor, 6.67 y 12.19 veces, respectivamente, comparados con pacientes que mostraron buena adherencia. Aun cuando no hubo una asociación estadística significativa, el FT tendió a ser más frecuente en adultos jóvenes, en pacientes con bajos ingresos y bajo nivel de educación. Cuando se compararon diferentes regímenes de TAR no hubo una diferencia aparente entre el FT en los regímenes basados en inhibidores no nucleósidos de la transcriptasa inversa y en aquellos basados en inhibidores de la proteasa. Esto es muy importante en el contexto de recientes estrategias de TAR, como es el caso de las iniciadas en forma temprana con el fin de lograr el control de la infección a largo plazo. Conclusiones: Se confirma la importancia de la adherencia al tratamiento para evitar el FT y la importancia de educar a los pacientes infectados con el VIH, especialmente aquellos individuos con un nivel socioeconómico bajo.

Characterization of treatment failure in HIV positive patients in the Colombian Caribbean region.

BACKGROUND: Treatment failure (TF) in patients receiving antiretroviral therapy against human immunodeficiency virus (HIV) is always a concern. OBJECTIVE: To examine the correlates associated with TF in patients living in the Colombian Caribbean city of Barranquilla, an aspect that was poorly studied in this region. METHODS: Treatment failure was evaluated in a cross-sectional study from virological, immunological and clinical standpoints. RESULTS: It was established that 29.5% of patients under highly active antiretroviral therapy (ART) could be considered in TF. Among those, virological failure was most frequent (20.9%), followed by immunological- (14.0%) and clinical failure (4.7%). In patients showing lack of adherence to the treatment, the likelihood of suffering from TF and virogical failure were respectively increased by 6.67-fold and 12.19-fold, compared with patients showing good adherence. Although there was no statistically significant association, TF tended to be more frequent in young adults, in patients with low income and, low level of education. When ART regimens were compared, there was no apparent difference in TF between regimens based on non-nucleoside reverse transcriptase inhibitors and those based on protease inhibitors. This is very important in the context of recent ART strategies, such as early-initiated ART, aimed at achieving long-term infection control. CONCLUSIONS: Is confirmed the importance of treatment adherence to avoid TF and further highlights the importance of educating HIV-infected patients in all parts of the world, especially those individuals with a lower socio-economic status.

OBJETIVOS: El fracaso terapéutico (FT) en pacientes que están recibiendo terapia antirretroviral contra el Virus de la Inmunodeficiencia Humana (VIH) ha sido siempre preocupante. OBJETIVO: Examinar las variables asociadas con el fracaso terapéutico, un problema que ha sido pobremente estudiado en la región, en pacientes que habitan en Barranquilla, ciudad del Caribe colombiano. MÉTODOS: El fracaso terapéutico fue evaluado en un estudio transversal desde los puntos de vista virológico, inmunológico y clínico. RESULTADOS: Se determinó que el 29.5% de los pacientes bajo terapia antirretroviral (TAR) de gran actividad podría considerase en fracaso terapéutico. El fracaso virológico fue el más frecuente (20.9%), seguido por el inmunológico (14.0%) y el clínico (4.7%). En pacientes que mostraron falta de adherencia al tratamiento, las posibilidades de presentar un fracaso terapéutico y virológico fue mayor, 6.67 y 12.19 veces, respectivamente, comparados con pacientes que mostraron buena adherencia. Aun cuando no hubo una asociación estadística significativa, el fracaso terapéutico tendió a ser más frecuente en adultos jóvenes, en pacientes con bajos ingresos y bajo nivel de educación. Cuando se compararon diferentes regímenes de TAR no hubo una diferencia aparente entre el fracaso terapéutico en los regímenes basados en inhibidores no nucleósidos de la transcriptasa inversa y en aquellos basados en inhibidores de la proteasa. Esto es muy importante en el contexto de recientes estrategias de TAR, como es el caso de las iniciadas en forma temprana con el fin de lograr el control de la infección a largo plazo. CONCLUSIONES: Se confirma la importancia de la adherencia al tratamiento para evitar el fracaso terapéutico y la importancia de educar a los pacientes infectados con el VIH, especialmente aquellos individuos con un nivel socioeconómico bajo.

Respiratory syncytial virus NS1 protein colocalizes with mitochondrial antiviral signaling protein MAVS following infection.

Respiratory syncytial virus (RSV) nonstructural protein 1(NS1) attenuates type-I interferon (IFN) production during RSV infection; however the precise role of RSV NS1 protein in orchestrating the early host-virus interaction during infection is poorly understood. Since NS1 constitutes the first RSV gene transcribed and the production of IFN depends upon RLR (RIG-I-like receptor) signaling, we reasoned that NS1 may interfere with this signaling. Herein, we report that NS1 is localized to mitochondria and binds to mitochondrial antiviral signaling protein (MAVS). Live-cell imaging of rgRSV-infected A549 human epithelial cells showed that RSV replication and transcription occurs in proximity to mitochondria. NS1 localization to mitochondria was directly visualized by confocal microscopy using a cell-permeable chemical probe for His(6)-NS1. Further, NS1 colocalization with MAVS in A549 cells infected with RSV was shown by confocal laser microscopy and immuno-electron microscopy. NS1 protein is present in the mitochondrial fraction and co-immunoprecipitates with MAVS in total cell lysatesof A549 cells transfected with the plasmid pNS1-Flag. By immunoprecipitation with anti-RIG-I antibody, RSV NS1 was shown to associate with MAVS at an early stage of RSV infection, and to disrupt MAVS interaction with RIG-I (retinoic acid inducible gene) and the downstream IFN antiviral and inflammatory response. Together, these results demonstrate that NS1 binds to MAVS and that this binding inhibits the MAVS-RIG-I interaction required for IFN production.

Cholesterol-rich microdomains as docking platforms for respiratory syncytial virus in normal human bronchial epithelial cells.

Respiratory syncytial virus (RSV) is one of the major causes of respiratory infections in children, and it is the main pathogen causing bronchiolitis in infants. The binding and entry mechanism by which RSV infects respiratory epithelial cells has not yet been determined. In this study, the earliest stages of RSV infection in normal human bronchial epithelial cells were probed by tracking virions with fluorescent lipophilic dyes in their membranes. Virions colocalized with cholesterol-containing plasma membrane microdomains, identified by their ability to bind cholera toxin subunit B. Consistent with an important role for cholesterol in RSV infection, cholesterol depletion profoundly inhibited RSV infection, while cholesterol repletion reversed this inhibition. Merger of the outer leaflets of the viral envelope and the cell membrane appeared to be triggered at these sites. Using small-molecule inhibitors, RSV infection was found to be sensitive to Pak1 inhibition, suggesting the requirement of a subsequent step of cytoskeletal reorganization that could involve plasma membrane rearrangements or endocytosis. It appears that RSV entry depends on its ability to dock to cholesterol-rich microdomains (lipid rafts) in the plasma membrane where hemifusion events begin, assisted by a Pak1-dependent process.

Biología molecular del virus sincitial respiratorio y desarrollo de estrategias profilácticas / Molecular biology of syncytial respiratory virus and development of phrophylactic strategies

El virus sincitial respiratorio es uno de los patógenos con la más alta prevalencia en infecciones deltracto respiratorio superior e inferior. Este virus desencadena cuadros tan severos como bronquiolitisen los lactantes y neumonías en los ancianos. El desarrollo de vacunas se ha visto afectado por lafalta de conocimiento respecto a cuál es el mecanismo inmunitario adecuado para prevenir la infección,además de la capacidad del virus para interferir con el desarrollo de la respuesta inmunitaria.El objetivo es revisar la biología molecular del virus, cómo éste puede interferir con la respuestainmunitaria y cómo este conocimiento previo ha servido para desarrollar estrategias profilácticastipo vacunas que aunque todavía están en escala del laboratorio lucen prometedoras. La fuente deinformación para esta revisión fueron los artículos publicados desde 1990 hasta la fecha en las revistasindexadas en ISI y PUBMED.

Respiratory syncytial virus is one of the pathogens with the highest prevalence in infections of upperand lower respiratory tracts. This virus triggers clinical phenotypes as severe as bronchiolytis ininfants and pneumonia in the elderly. The development of vaccines has been hampered by the lackof knowledge regarding the adequate immune mechanism able to address the infection as well as theability of the virus to interfere with the development of a complete immune response. The aim ofthis paper is to review the molecular biology aspects of the virus; how the virus is able to interferewith the immune response; and how this previous knowledge has helped us to develop prophylacticstrategies as vaccines, which they look promising even though they are still at bench scale. Thesource for this review came from articles published from 1990 until today in journal indexed in ISIand PUBMED.

Inhibition of respiratory syncytial virus infection with intranasal siRNA nanoparticles targeting the viral NS1 gene.

Respiratory syncytial virus (RSV) infection is one of the major causes of respiratory tract infection for which no vaccine or antiviral treatment is available. The RSV NS1 protein seems to antagonize the host interferon (IFN) response; however, its mechanism is unknown. Here, we used a plasmid-borne small interfering RNA targeting the NS1 gene (siNS1) to examine the role of NS1 in modulating RSV infection. RSV replication was reduced in A549 cells, but not IFN-deficient Vero cells, transfected with siNS1. siNS1 induced upregulated expression of IFN-beta and IFN-inducible genes in A549 cells. siNS1-transfected human dendritic cells, upon RSV infection, produced elevated type-1 IFN and induced differentiation of naive CD4+ T cells to T helper type 1 (TH1) cells. Mice treated intranasally with siNS1 nanoparticles before or after infection with RSV showed substantially decreased virus titers in the lung and decreased inflammation and airway reactivity compared to controls. Thus, siNS1 nanoparticles may provide an effective inhibition of RSV infection in humans.

Protein kinase C-alpha activity is required for respiratory syncytial virus fusion to human bronchial epithelial cells.

Respiratory syncytial virus (RSV) infection activates protein kinase C (PKC), but the precise PKC isoform(s) involved and its role(s) remain to be elucidated. On the basis of the activation kinetics of different signaling pathways and the effect of various PKC inhibitors, it was reasoned that PKC activation is important in the early stages of RSV infection, especially RSV fusion and/or replication. Herein, the role of PKC-alpha during the early stages of RSV infection in normal human bronchial epithelial cells is determined. The results show that the blocking of PKC-alpha activation by classical inhibitors, pseudosubstrate peptides, or the overexpression of dominant-negative mutants of PKC-alpha in these cells leads to significantly decreased RSV infection. RSV induces phosphorylation, activation, and cytoplasm-to-membrane translocation of PKC-alpha. Also, PKC-alpha colocalizes with virus particles and is required for RSV fusion to the cell membrane. Thus, PKC-alpha could provide a new pharmacological target for controlling RSV infection.

Mite and cockroach proteases activate p44/p42 MAP kinases in human lung epithelial cells.

BACKGROUND: The mechanisms underlying epithelial cell activation by indoor inhaled antigens are poorly understood. METHODS: In this study, we investigated the role of mitogen-activated protein kinases (MAPKs) in A549 epithelial cells upon exposure to antigens of house dust mite (HDMA), German cockroach (GCA), and American cockroach (ACA). RESULTS: Each of these antigens induced a significant increase in IL-8 levels compared to the medium control. Exposure of A549 cells to these antigens induced the phosphorylation of p44/42 MAPKs within 5 minutes, which reached a peak at 25 minutes later and reached baseline levels at 1 hour after exposure. PD98059, a MEK1 inhibitor, significantly decreased phosphorylation of p44/p42 MAPKs and IL-8 production. Exposure of A549 cells with antigens, which had been preincubated with different protease inhibitors, also resulted in a reduction of both MAPK phosphorylation and IL-8 production. CONCLUSION: Thus, proteolytic antigens present in HDMA, GCA and ACA activate the p44/42 MAPKs airway epithelial cells, which lead to elevated IL-8 production and initiation of the inflammatory cascade.