Cable Pili and the Associated 22 Kda Adhesin Contribute to Burkholderia Cenocepacia Persistence In Vivo

Infection by Burkholderia cenocepacia in cystic fibrosis (CF) patients is associated with poor clinical prognosis. Previously, we demonstrated that one of the highly transmissible strains, BC7, expresses cable pili and the associated 22 kDa adhesin, both of which contribute to BC7 binding to airway epithelial cells. However, the contribution of these factors to induce inflammation and bacterial persistence in vivo is not known.Wild-type BC7 stimulated higher IL-8 responses than the BC7 cbl and BC7 adhA mutants in both CF and normal bronchial epithelial cells. To determine the role of cable pili and the associated adhesin, we characterized a mouse model of B. cenocepacia, where BC7 are suspended in Pseudomonas aeruginosa alginate. C57BL/6 mice were infected intratracheally with wild-type BC7 suspended in either alginate or PBS and were monitored for lung bacterial load and inflammation. Mice infected with BC7 suspended in PBS completely cleared the bacteria by 3 days and resolved the inflammation. In contrast, mice infected with BC7 suspended in alginate showed persistence of bacteria and moderate lung inflammation up to 5 days post-infection. Using this model, mice infected with the BC7 cbl and BC7 adhA mutants showed lower bacterial loads and mild inflammation compared to mice infected with wild-type BC7. Complementation of the BC7 cblS mutation in trans restored the capacity of this strain to persist in vivo. Immunolocalization of bacteria revealed wild-type BC7 in both airway lumen and alveoli, while the BC7 cbl and BC7 adhA mutants were found mainly in airway lumen and peribronchiolar region.B. cenocepacia suspended in alginate can be used to determine the capacity of bacteria to persist and cause lung inflammation in normal mice. Both cable pili and adhesin contribute to BC7-stimulated IL-8 response in vitro, and BC7 persistence and resultant inflammation in vivo

Viruses exacerbating chronic pulmonary disease: the role of immune modulation

Chronic pulmonary diseases are a major cause of morbidity and mortality and their impact is expected to increase in the future. Respiratory viruses are the most common cause of acute respiratory infections and it is increasingly recognized that respiratory viruses are a major cause of acute exacerbations of chronic pulmonary diseases such as asthma, chronic obstructive pulmonary disease and cystic fibrosis. There is now increasing evidence that the host response to virus infection is dysregulated in these diseases and a better understanding of the mechanisms of abnormal immune responses has the potential to lead to the development of new therapies for virus-induced exacerbations. The aim of this article is to review the current knowledge regarding the role of viruses and immune modulation in chronic pulmonary diseases and discuss avenues for future research and therapeutic implications

Targeting IL-1β and IL-17A driven inflammation during influenza-induced exacerbations of chronic lung inflammation.

For patients with chronic lung diseases, such as chronic obstructive pulmonary disease (COPD), exacerbations are life-threatening events causing acute respiratory distress that can even lead to hospitalization and death. Although a great deal of effort has been put into research of exacerbations and potential treatment options, the exact underlying mechanisms are yet to be deciphered and no therapy that effectively targets the excessive inflammation is available. In this study, we report that interleukin-1β (IL-1β) and interleukin-17A (IL-17A) are key mediators of neutrophilic inflammation in influenza-induced exacerbations of chronic lung inflammation. Using a mouse model of disease, our data shows a role for IL-1β in mediating lung dysfunction, and in driving neutrophilic inflammation during the whole phase of viral infection. We further report a role for IL-17A as a mediator of IL-1β induced neutrophilia at early time points during influenza-induced exacerbations. Blocking of IL-17A or IL-1 resulted in a significant abrogation of neutrophil recruitment to the airways in the initial phase of infection or at the peak of viral replication, respectively. Therefore, IL-17A and IL-1β are potential targets for therapeutic treatment of viral exacerbations of chronic lung inflammation

Gastrointestinal events and association with initiation of treatment for osteoporosis

Ankita Modi,1 Ethel S Siris,2 Jackson Tang,3 Shiva Sajjan,1 Shuvayu S Sen1 1Center for Observational and Real-World Evidence, Merck & Co., Inc, Kenilworth, NJ, 2Toni Stabile Osteoporosis Center, Columbia University Medical Center, NY Presbyterian Hospital, New York, NY, 3Asclepius Analytics Ltd, Brooklyn, NY, USA Background: Preexisting gastrointestinal (GI) events may deter the use of pharmacologic treatment in patients diagnosed with osteoporosis (OP). The objective of this study was to examine the association between preexisting GI events and OP pharmacotherapy initiation among women diagnosed with OP. Methods: The study utilized claims data from a large US managed care database to identify women aged ≥55 years with a diagnosis code for OP (index date) during 2002–2009. Patients with a claim for pharmacologic OP treatment in the 12-month pre-index period (baseline) were excluded. OP treatment initiation in the post-index period was defined as a claim for bisphosphonates (alendronate, ibandronate, risedronate, zoledronic acid), calcitonin, raloxifene, or teriparatide. During the post-index period (up to 12 months), GI events were identified before treatment initiation. A time-dependent Cox regression model was used to investigate the likelihood of initiating any OP treatment. Among patients initiating OP treatment, a discrete choice model was utilized to assess the relationship between post-index GI events and likelihood of initiating with a bisphosphonate versus a non-bisphosphonate. Results: In total, 65,344 patients (mean age 66 years) were included; 23.7% had a GI event post diagnosis and before treatment initiation. Post-index GI events were associated with a 75% lower likelihood of any treatment initiation (hazard ratio 0.25; 95% confidence interval 0.24–0.26). Among treated patients (n=23,311), those with post-index GI events were 39% less likely to receive a bisphosphonate versus a non-bisphosphonate (odds ratio 0.61; 95% confidence interval 0.54–0.68). Conclusion: GI events after OP diagnosis were associated with a decreased likelihood of OP treatment initiation and an increased likelihood of treatment initiation with a non-bisphosphonate versus a bisphosphonate. Keywords: osteoporosis, postmenopausal, bisphosphonates, prescribing pattern

Burkholderia cenocepacia Type VI Secretion System Mediates Escape of Type II Secreted Proteins into the Cytoplasm of Infected Macrophages

<div><p><em>Burkholderia cenocepacia</em> is an opportunistic pathogen that survives intracellularly in macrophages and causes serious respiratory infections in patients with cystic fibrosis. We have previously shown that bacterial survival occurs in bacteria-containing membrane vacuoles (BcCVs) resembling arrested autophagosomes. Intracellular bacteria stimulate IL-1β secretion in a caspase-1-dependent manner and induce dramatic changes to the actin cytoskeleton and the assembly of the NADPH oxidase complex onto the BcCV membrane. A Type 6 secretion system (T6SS) is required for these phenotypes but surprisingly it is not required for the maturation arrest of the BcCV. Here, we show that macrophages infected with <em>B. cenocepacia</em> employ the NLRP3 inflammasome to induce IL-1β secretion and pyroptosis. Moreover, IL-1β secretion by <em>B. cenocepacia-</em>infected macrophages is suppressed in deletion mutants unable to produce functional Type VI, Type IV, and Type 2 secretion systems (SS). We provide evidence that the T6SS mediates the disruption of the BcCV membrane, which allows the escape of proteins secreted by the T2SS into the macrophage cytoplasm. This was demonstrated by the activity of fusion derivatives of the T2SS-secreted metalloproteases ZmpA and ZmpB with adenylcyclase. Supporting this notion, ZmpA and ZmpB are required for efficient IL-1β secretion in a T6SS dependent manner. ZmpA and ZmpB are also required for the maturation arrest of the BcCVs and bacterial intra-macrophage survival in a T6SS-independent fashion. Our results uncover a novel mechanism for inflammasome activation that involves cooperation between two bacterial secretory pathways, and an unanticipated role for T2SS-secreted proteins in intracellular bacterial survival.</p> </div