Induction of neutrophil apoptosis and treatment of severe lung inflammation

Inflammatory lung diseases like chronic bronchitis and emphysema (COPD) and scarring conditions are responsible for a huge burden of illness and untimely deaths in the UK, but current treatments are at best poorly-effective. Over the past twenty years we have been taking an alternative approach to harness the mechanisms by which some inflammatory responses are known to get better spontaneously. Specifically we have identified a mechanism by which key inflammatory cells called neutrophils can be made to commit suicide and be removed silently by local scavenger cells called macrophages. Unfortunately this suicide process is usually overcome by powerful survival factors present in the inflamed lung.
In work newly-published in the leading international medical science journal Nature Medicine we have shown that a CDK inhibitor called R-roscovitine, currently under clinical trial in cancer patients, causes a hitherto unexpected induction of neutrophil suicide, even in the presence of survival factors, and makes relevant models of human inflammatory lung disease resolve. This work has recently been publicised in the lay press.
In our proposed programme of research we will define exactly how this works, an approach which may lead to the discovery of other useful anti-inflammatory drugs. We will also carry out a clinical study of the drug s effectiveness using cutting-edge imaging technology to monitor the progress of the disease non-invasively and demonstrate its response to treatment.

Inflammatory lung diseases like COPD, ARDS and interstitial lung diseases (ILD) are an MRC priority for research. Characterised by the persistent accumulation of neutrophils associated with architectural disruption and fibrosis, they are highly resistant to treatment with glucocorticoids and there is a pressing need to identify new therapies. However, under other circumstances even massive inflammatory responses can resolve spontaneously and completely, as exemplified by the dramatic resolution of the pulmonary inflammatory response in streptococcal pneumonia. We have been investigating the resolution mechanisms of inflammation with the aim of harnessing them for therapeutic benefit in inflammatory disease.
The neutrophil, specifically implicated in the pathogenesis of these diseases, was thought to meet its fate in situ by necrosis, despite the predictable histotoxic and pro-inflammatory consequences. Twenty years ago we discovered that the extravasated neutrophil undergoes apoptosis, whereby in contrast it shuts down secretion and is cleared intact by macrophages employing a novel recognition mechanism which fails to provoke release of pro-inflammatory mediators. In an investigative strategy designed to !Ydrive!
this cellular pathway in persistent inflammation, we demonstrated that inflammatory mediators like GM-CSF markedly retarded neutrophil apoptosis (a property shared with glucocorticoids; perhaps partly explaining their relative ineffectiveness in many inflammatory diseases). We then identified a variety of agents which induced granulocyte apoptosis in vitro, but their effects of were overridden by inflammatory mediators known to be present at inflamed sites. However, we have now shown that R-roscovitine and other CDK inhibitors not only induce apoptosis in stimulated inflammatory neutrophils by a mechanism involving down-regulation of the neutrophil survival factors Mcl-1 and XIAP but also dramatically enhance inflammatory resolution in clinically-relevant models of human lung disease.
In order to prove our hypothesis that the pro-resolution effects of CDK inhibitors are mediated specifically through the neutrophil s apoptotic machinery, we will now employ incisive tools (HIV-tat, siRNA and Cre-Lox) to identify CDKs of specific importance and dissect the roles of NFkB and Mcl-1 and other possible survival proteins of the Bcl-2 family in vitro, together with conditional knockouts of Mcl-1 and candidate CDKs in vivo. In parallel we will confirm the efficacy of CDK inhibitors, and demonstrate the value of 18F-FDG PET and other non-invasive biomarkers in murine bleomycin lung injury and in a randomised double-blind study of R-roscovitine (with and without glucocorticoids) of human IPF, in a new approach to the treatment of inflammatory diseases of the lung and other organs.