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Kimmey, J. M.

Publications and source records attributed to Kimmey, J. M..

2 recordsLinked to original sources
bioRxiv2020

Role of Inflammasome-independent Activation of IL-1β by the Pseudomonas aeruginosa Protease LasB

Pulmonary damage by Pseudomonas aeruginosa during cystic fibrosis lung infection and ventilator-associated pneumonia is mediated both by pathogen virulence factors and host inflammation. Impaired immune function due to tissue damage and inflammation, coupled with pathogen multidrug resistance, complicates management of these deep-seated infections. Therefore, preservation of lung function and effective immune clearance may be enhanced by selectively controlling inflammation. Pathological inflammation during P. aeruginosa pneumonia is driven by interleukin-1{beta} (IL-1{beta}). This proinflammatory cytokine is canonically regulated by caspase-family inflammasome proteases, but we report that plasticity in IL-1{beta} proteolytic activation allows for its direct maturation by the pseudomonal protease LasB. LasB promotes IL-1{beta} activation, neutrophilic inflammation, and destruction of lung architecture characteristic of severe P. aeruginosa pulmonary infection. Discovery of this IL-1{beta} regulatory mechanism provides a distinct target for anti-inflammatory therapeutics, such that matrix metalloprotease inhibitors blocking LasB limit inflammation and pathology during P. aeruginosa pulmonary infections. HighlightsO_LIIL-1{beta} drives pathology during pulmonary infection by Pseudomonas aeruginosa. C_LIO_LIThe Pseudomonas protease LasB cleaves and activates IL-1{beta} independent of canonical and noncanonical inflammasomes C_LIO_LIMetalloprotease inhibitors active against LasB limit inflammation and bacterial growth C_LI Research in ContextInflammation is highly damaging during lung infections by the opportunistic pathogen Pseudomonas aeruginosa. Sun et al. demonstrate that the Pseudomonas LasB protease directly activates IL-1{beta} in an inflammasome-independent manner. Inhibition of IL-1{beta} conversion by LasB protects against neutrophilic inflammation and destruction of the lung. Adjunctive therapeutics that limit pathological inflammation induced by infection would be beneficial for the treatment of pulmonary infections when used with conventional antibiotics.

microbiology↗
bioRxiv2020

Exploration of bacterial bottlenecks and Streptococcus pneumoniae pathogenesis by CRISPRi-seq

Streptococcus pneumoniae is a commensal bacterium of the human nasopharynx, but can cause harmful infections if it spreads to other parts of the body, such as pneumonia, sepsis or meningitis. To facilitate pathogenesis studies, we constructed a doxycycline-inducible pooled CRISPR interference (CRISPRi) library targeting all operons in protypical S. pneumoniae strain D39V. Our library design allows fitness within the pool to be assessed by a one-step PCR reaction directly followed by Illumina sequencing (CRISPRi-seq). The doxycycline-inducible CRISPRi system is tightly controllable and suitable for both bottleneck exploration and evaluation of gene fitness in vitro and in vivo. Here, we applied CRISPRi-seq to identify genetic factors important for causing pneumococcal pneumonia. Mice were infected intratracheally with our CRISPRi library and bacteria collected at 24 h (from lung) and 48 h (from both lung and blood) post-infection. CRISPRi-seq showed a critical bottleneck at 48 h after intratracheal infection, with only a few bacteria surviving the brunt of the innate immune response to cause systemic infection. However, earlier at 24 h post-infection, many significant differences in gene fitness cost between in vitro and in vivo conditions were identified, including genes encoding known and putative novel virulence factors, genes essential only in vivo, and genes essential only in vitro. A key advantage of CRISPRi-seq over traditional transposon-based genetic screens is that all genes, including essential genes, can be tested for their role in virulence and pathogenicity. The approaches developed here should be generally applicable to study infection bottlenecks and in vivo fitness for other important human and animal pathogens.

microbiology↗