Increased expression of upstream TH2-cytokines in a mouse model of viral-induced asthma exacerbation

Additional file 2: Table S2. Primary and secondary antibodies used during western blot analysis of lung homogenate samples. All primary antibodies were diluted in TBS-T with 5 % BSA, while the secondary antibody was diluted in TBS-T with 5 % milk

Imiquimod shows anti-viral actions in human bronchial epithelium - implications for COVID-19 treatment

Introduction: Combining anti-viral and anti-inflammatory effects in a single drug may be beneficial in treating COVID-19. We hypothesized that the TLR7 agonist imiquimod (imq) may exert these actions in human bronchial epithelial cells (HBECs), which are targets in SARS-CoV-2 mediated lung injury. Methods: Using primary HBECs from asthmatic donors (N=18), we explored actions of imq related to airway viral resistance and tolerance. HBECs were treated with imq alone or in combination with the viral mimic poly (I:C) or the SARS-CoV-2 spike protein 1 (SP1). Anti-viral and pro-inflammatory mediators were analyzed by Luminex, RT-qPCR and mRNA gene pathway analysis. Results: imq treatment alone induced IFN-ß and CCL5 (p<0.05) mRNA and reduced transcription of IL-1ß (p<0.01) at 24h. In SP1 or poly (I:C) stimulated HBECs, treatment with imq augmented IFN-ß mRNA expression by a 2-fold, respectively (p<0.05). Imq in combination with poly (I:C) decreased protein release of IL-8, CCL5, IL-1ß and IL-6 (p<0.05). Furthermore, gene pathway analysis revealed that imq enriched poly(I:C)-induced IFN signaling, IL-20 family signaling (epithelial repair), antigen presentation and cytokine signaling. Enriched cytokine signaling genes included negative regulators such as IKBKG and SIGIRR. Conclusion: imq exerts distinct anti-viral resistance effects in HBECs by increasing anti-viral signaling and improves viral infection tolerance by diminishing epithelial cytokines potentially involved in severe COVID-19. Our findings highlight a possibility of developing dual action drugs suitable for anti-SARS-CoV-2 treatment

Antagonism of the prostaglandin D(2 )receptor CRTH2 attenuates asthma pathology in mouse eosinophilic airway inflammation

BACKGROUND: Mast cell-derived prostaglandin D(2 )(PGD(2)), may contribute to eosinophilic inflammation and mucus production in allergic asthma. Chemoattractant receptor homologous molecule expressed on TH(2 )cells (CRTH2), a high affinity receptor for prostaglandin D(2), mediates trafficking of TH(2)-cells, mast cells, and eosinophils to inflammatory sites, and has recently attracted interest as target for treatment of allergic airway diseases. The present study involving mice explores the specificity of CRTH2 antagonism of TM30089, which is structurally closely related to the dual TP/CRTH2 antagonist ramatroban, and compares the ability of ramatroban and TM30089 to inhibit asthma-like pathology. METHODS: Affinity for and antagonistic potency of TM30089 on many mouse receptors including thromboxane A(2 )receptor mTP, CRTH2 receptor, and selected anaphylatoxin and chemokines receptors were determined in recombinant expression systems in vitro. In vivo effects of TM30089 and ramatroban on tissue eosinophilia and mucus cell histopathology were examined in a mouse asthma model. RESULTS: TM30089, displayed high selectivity for and antagonistic potency on mouse CRTH2 but lacked affinity to TP and many other receptors including the related anaphylatoxin C3a and C5a receptors, selected chemokine receptors and the cyclooxygenase isoforms 1 and 2 which are all recognized players in allergic diseases. Furthermore, TM30089 and ramatroban, the latter used as a reference herein, similarly inhibited asthma pathology in vivo by reducing peribronchial eosinophilia and mucus cell hyperplasia. CONCLUSION: This is the first report to demonstrate anti-allergic efficacy in vivo of a highly selective small molecule CRTH2 antagonist. Our data suggest that CRTH2 antagonism alone is effective in mouse allergic airway inflammation even to the extent that this mechanism can explain the efficacy of ramatroban

C57Bl/6N mice have an attenuated lung inflammatory response to dsRNA compared to C57Bl/6J and BALB/c mice

Background Lower respiratory infections caused by ssRNA viruses are a major health burden globally. Translational mouse models are a valuable tool for medical research, including research on respiratory viral infections. In in vivo mouse models, synthetic dsRNA can be used as a surrogate for ssRNA virus replication. However, studies investigating how genetic background of mice impacts the murine lung inflammatory response to dsRNA is lacking. Hence, we have compared lung immunological responses of BALB/c, C57Bl/6N and C57Bl/6J mice to synthetic dsRNA. Methods dsRNA was administered intranasally to BALB/c, C57Bl/6N and C57Bl/6J mice once/day for three consecutive days. Lactate dehydrogenase (LDH) activity, inflammatory cells, and total protein concentration were analyzed in bronchoalveolar lavage fluid (BALF). Pattern recognition receptors levels (TLR3, MDA5 and RIG-I) were measured in lung homogenates using RT-qPCR and western blot. Gene expression of IFN-β, TNF-α, IL-1β and CXCL1 was assessed in lung homogenates by RT-qPCR. ELISA was used to analyze protein concentrations of CXCL1 and IL-1β in BALF and lung homogenates. Results BALB/c and C57Bl/6J mice showed infiltration of neutrophils to the lung, and an increase in total protein concentration and LDH activity in response to dsRNA administration. Only modest increases in these parameters were observed for C57Bl/6N mice. Similarly, dsRNA administration evoked an upregulation of MDA5 and RIG-I gene and protein expression in BALB/c and C57Bl/6J, but not C57Bl/6N, mice. Further, dsRNA provoked an increase in gene expression of TNF-α in BALB/c and C57Bl/6J mice, IL-1β only in C57Bl/6N mice and CXCL1 exclusively in BALB/c mice. BALF levels of CXCL1 and IL-1β were increased in BALB/c and C57Bl/6J mice in response to dsRNA, whereas the response of C57Bl/6N was blunt. Overall, inter-strain comparisons of the lung reactivity to dsRNA revealed that BALB/c, followed by C57Bl/6J, had the most pronounced respiratory inflammatory responses, while the responses of C57Bl/6N mice were attenuated. Conclusions We report clear differences of the lung innate inflammatory response to dsRNA between BALB/c, C57Bl/6J and C57Bl/6N mice. Of particular note, the highlighted differences in the inflammatory response of C57Bl/6J and C57Bl/6N substrains underscore the value of strain selection in mouse models of respiratory viral infections

Development and Resolution of Allergic Airway Inflammation in vivo: effects of therapeutic intervention

Eosinophils, containing tissue toxic granule proteins, are regarded a culprit cell in asthma pathogenesis. Using animal and human experimental models of asthma effects on eosinophilic airway inflammation were investigated in vivo. The current research paradigm regarding spontaneous and steroid-induced clearance of airway tissue eosinophils exclusively involves death through apoptosis followed by phagocytosis of the apoptotic eosinophils. Since this paradigm is based on observations in vitro and in airway lumen, in vivo studies on occurrence of eosinophil apoptosis in airway tissues are urgently warranted. Using well-validated techniques we demonstrated that eosinophil apoptosis may not occur, not even at spontaneous or steroid-induced resolution of airway eosinophilic inflammation. Yet, by Fas-receptor stimulation in mouse allergic airways, we could for the first time produce apoptotic eosinophils in lung tissues. However, instead of being phagocytosed most apoptotic eosinophils underwent secondary necrosis. Fas-receptor stimulation also induced direct cytolysis of non-apoptotic eosinophils, a mode of death and degranulation that also occurs in asthma. Consequently, airway inflammation was greatly aggravated. Indeed, our in vivo studies involving Fas-induced eosinophil apoptosis turned a promising asthma treatment modality? into a mechanism causing exacerbation of airway inflammation. Furthermore, we demonstrated that eosinophil cell clearance in vivo involved trans-epithelial migration of cells into the airway lumen. This luminal entry mechanism allowed 350 000 eosinophils/cm2 airway mucosal surface to be cleared from the airway tissue each minute without affecting the epithelial integrity. Once in the lumen some eosinophils underwent apoptosis before being removed, likely by mucociliary clearance or coughing. Hence, we suggest that facilitating cell clearance by luminal entry may constitute an important characteristic of future treatments that shall resolve airway inflammatory conditions. Interestingly, we discovered that steroid treatment permitted luminal entry of eosinophils while it inhibited selectively the CC-chemokine RANTES. These data suggest that inhibiting RANTES-dependent cell recruitment and promoting clearance of inflammatory cells into the airway lumen are significant components of the pharmacology of therapeutic steroids