The Inhibition of Phosphoinositide-3 Kinases Induce Resolution of Inflammation in a Gout Model

Phosphoinositide-3 kinases (PI3Ks) are central signaling enzymes that are involved in many aspects of immune cell function. PI3Kγ and PI3Kδ are the major isoforms expressed in leukocytes. The role of PI3K isoforms in the resolution of inflammation is still poorly understood. Here, we investigated the contribution of PI3Kγ and PI3Kδ to the resolution of inflammation in a model of gout in mice.

Methods and Results: Experiments were performed in wild-type male C57/Bl6 mice. Selective inhibitors of PI3K-γ (AS605240) or PI3Kδ (GSK045) were injected in the joint 12 h after injection of MSU crystals, hence at the peak of inflammation. Inhibition of either PI3K isoform decreased number of neutrophils that migrated in response to the injection of MSU crystals. This was associated with reduction of myeloperoxidase activity and IL-1β levels in periarticular tissues and reduction of histological score. Joint dysfunction, as seen by reduced mechanical hypernociception, was improved by treatment with either inhibitor. The decrease in neutrophil numbers was associated with enhanced apoptosis and efferocytosis of these cells. There was shortening of resolution intervals, suggesting inhibition of either isoform induced the resolution of neutrophilic inflammation. Blockade of PI3Kγ or PI3Kδ reduced Nuclear Factor kappa B (NF-κB) activation. A pan-PI3K inhibitor (CL27c) reduced inflammation induced by MSU crystals by a magnitude that was similar to that attained by the PI3Kγ or PI3Kδ selective inhibitors alone.

Conclusion: Taken together, these results suggest that neutrophils can use PI3Kγ or PI3Kδ to remain in the cavity and blockade of either isoenzyme is sufficient to induce their apoptosis and resolve inflammation in a murine model of gout.

Inhalation of the prodrug PI3K inhibitor CL27c improves lung function in asthma and fibrosis

PI3K activation plays a central role in the development of pulmonary inflammation and tissue remodeling. PI3K inhibitors may thus offer an improved therapeutic opportunity to treat non-resolving lung inflammation but their action is limited by unwanted on-target systemic toxicity. Here we present CL27c, a prodrug pan-PI3K inhibitor designed for local therapy, and investigate whether inhaled CL27c is effective in asthma and pulmonary fibrosis. Mice inhaling CL27c show reduced insulin-evoked Akt phosphorylation in lungs, but no change in other tissues and no increase in blood glycaemia, in line with a local action. In murine models of acute or glucocorticoid-resistant neutrophilic asthma, inhaled CL27c reduces inflammation and improves lung function. Finally, inhaled CL27c administered in a therapeutic setting protects from bleomycin-induced lung fibrosis, ultimately leading to significantly improved survival. Therefore, local delivery of a pan-PI3K inhibitor prodrug reduces systemic on-target side effects but effectively treats asthma and irreversible pulmonary fibrosis.

Activation of PI3K plays a role in pulmonary inflammation. Here, the authors develop a drug inhibitor of PI3K, and show that it inhibits lung inflammation and damage in mouse models of asthma and lung fibrosis.

Abstract 4988: PI3Kγ-deficiency protects against pancreatic tumorigenesis at the expense of diet-Induced hyperlipidemia and hepatotoxicity

Pancreatic ductal adenocarcinoma (PDAC) presents a significant challenge clinically, with poor overall survival and widespread resistance to conventional therapies. Several novel molecular targets are being considered in the management of PDAC patients. To this end, as hyperactive PI3K signaling is implicated in both disease incidence and progression, the inhibition of PI3K p110γ isoform is showing early promise in vivo and has been proposed as a reasonable target for therapy. Classically, p110γ is expressed predominantly in macrophages. However, using both primary pancreatic cancer samples and established patient databases, we found that p110γ is commonly upregulated in the cancer epithelium. Further, p110γ is expressed in human cell lines, and the pharmacologic inhibition of p110γ with AS-604850 both delayed mtKRAS/mtTP53-induced acinar-to-ductal metaplasia ex vivo, and sensitized tumor cells to gemcitabine in vitro. Given the apparent importance of epithelial p110γ to the neoplastic phenotype, we next generated mice with constitutive activation of p110γ targeted to the exocrine pancreas (PI3KγCA). When combined with a KRAS activating mutation, PI3KγCA mice developed highly advanced disease forms with robust fibrosis, inflammation, and AKT activation/proliferation. In accordance with these observations, both homo- and heterozygous global deletion of p110γ protected against KRAS-induced tumorigenesis, reducing downstream AKT signaling and proliferation in vivo. However, despite the reduction in tumor burden, mutant KRAS mice with p110γ-deficiency displayed early signs of hepatotoxicity. Since p110γ has several key roles in lipid metabolism, we next assessed p110γ loss in the setting of a high-fat diet (HFD). These mtKRAS/p110γKO mice developed pronounced hyperlipidemia and severe hepatic cell injury/steatosis. Additionally, the previously observed protective effect in the pancreas was markedly diminished, and neoplastic tissues displayed pronounced AKT pathway activation, indicating potential compensatory signaling through non-p110γ isoforms. Indeed, how p110γ loss and lipid accumulation in liver impact development of mtKRAS-induced neoplasia and cancer is a very interesting future aim. Combined, these observations suggest that systemic p110γ inhibition should be carefully considered, particularly given the potential for reduced efficacy, hyperlipidemia, and hepatic injury in obese patients, unless specific targeting to the pancreas can be achieved.

Citation Format: Carolina Torres, Daniel R. Principe, Alex Park, Ronald McKinney, Matthew J. Dorman, Ajay Rana, Emilio Hirsch, Jose Cordoba-Chacon, Paul J. Grippo. PI3Kγ-deficiency protects against pancreatic tumorigenesis at the expense of diet-Induced hyperlipidemia and hepatotoxicity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4988.

Application of hydroxypropyl methylcellulose as a protective agent against magnesium stearate induced crystallization of amorphous itraconazole

Itraconazole is a fungicide drug which has low bioavailability due to its poor water solubility. Amorphous solid dispersion (ASD) is a tool that has the potential to greatly increase the dissolution rate and extent of compounds. In this work, the dissolution of tablets containing the ASD of itraconazole with either hydroxypropyl methylcellulose (HPMC) or vinylpyrrolidone-vinyl acetate copolymer (PVPVA) was compared in order to find a formulation which can prevent the drug from the precipitation caused by magnesium stearate. Formulations containing the PVPVA-based ASD with HPMC included in various forms could reach 90% dissolution in 2 h, while HPMC-based ASDs could release 100% of the drug. However, HPMC-based ASD had remarkably poor grindability and low bulk density, which limited its processability and applicability. The latter issue could be resolved by roller compacting the ASD, which significantly increases the bulk density and the flowability of the powder blends used for tableting. This roller compaction step might be a base for the industrial application of HPMC-based, electrospun ASDs.

Protumor Steering of Cancer Inflammation by p50 NF-κB Enhances Colorectal Cancer Progression

Although tumor-associated macrophages (TAM) display a M2-skewed tumor-promoting phenotype in most cancers, in colorectal cancer, both TAM polarization and its impact remain controversial. We investigated the role of the M2-polarizing p50 NF-κB subunit in orchestrating TAM phenotype, tumor microenvironment composition, and colorectal cancer progression. We first demonstrated, by parallel studies in colitis-associated cancer (CAC) and in genetically driven Apc^Min mouse models, that the p50-dependent inhibition of M1-polarized gut inflammation supported colorectal cancer development. In accordance with these studies, p50^-/- mice displayed exacerbated CAC with fewer and smaller tumors, along with enhanced levels of M1/Th1 cytokines/chemokines, including IL12 and CXCL10, whose administration restrained CAC development in vivo The inflammatory profile supporting tumor resistance in colons from p50^-/- tumor bearers correlated inversely with TAM load and positively with both recruitment of NK, NKT, CD8⁺ T cells and number of apoptotic tumor cells. In agreement, myeloid-specific ablation of p50 promoted tumor resistance in mice, whereas in colorectal cancer patients, a high number of p50⁺ TAMs at the invasive margin was associated with decreased IL12A and TBX21 expression and worse postsurgical outcome. Our findings point to p50 involvement in colorectal cancer development, through its engagement in the protumor activation of macrophages, and identify a candidate for prognostic and target therapeutic intervention. Cancer Immunol Res; 6(5); 578-93. ©2018 AACR.

The turtle and the rabbit story in a modern (PI3)key

Mitosis is a complex process controlling proper distribution of chromosomes and preventing genomic instability, a typical hallmark of cancer. We recently reported that that a class II isoform of Phosphoinositide 3-kinase (PI3K), PI3K-C2α, is involved in the organization of the mitotic spindle. Our study demonstrate that, differently to all other PI3K isoforms, PI3K-C2α shows an unexpected tumor suppressor function independent of its catalytic activity.

Functions of PDE3 Isoforms in Cardiac Muscle

Isoforms in the PDE3 family of cyclic nucleotide phosphodiesterases have important roles in cyclic nucleotide-mediated signalling in cardiac myocytes. These enzymes are targeted by inhibitors used to increase contractility in patients with heart failure, with a combination of beneficial and adverse effects on clinical outcomes. This review covers relevant aspects of the molecular biology of the isoforms that have been identified in cardiac myocytes; the roles of these enzymes in modulating cAMP-mediated signalling and the processes mediated thereby; and the potential for targeting these enzymes to improve the profile of clinical responses.

The innate immune system in chronic cardiomyopathy: a European Society of Cardiology (ESC) scientific statement from the Working Group on Myocardial Function of the ESC

Activation of the immune system in heart failure (HF) has been recognized for over 20 years. Initially, experimental studies demonstrated a maladaptive role of the immune system. However, several phase III trials failed to show beneficial effects in HF with therapies directed against an immune activation. Preclinical studies today describe positive and negative effects of immune activation in HF. These different effects depend on timing and aetiology of HF. Therefore, herein we give a detailed review on immune mechanisms and their importance for the development of HF with a special focus on commonalities and differences between different forms of cardiomyopathies. The role of the immune system in ischaemic, hypertensive, diabetic, toxic, viral, genetic, peripartum, and autoimmune cardiomyopathy is discussed in depth. Overall, initial damage to the heart leads to disease specific activation of the immune system whereas in the chronic phase of HF overlapping mechanisms occur in different aetiologies.

Therapeutic Targeting of PDEs and PI3K in Heart Failure with Preserved Ejection Fraction (HFpEF)

PURPOSE OF REVIEW

Heart Failure with preserved Ejection Fraction (HFpEF) is a prevalent disease with considerable individual and societal burden. HFpEF patients often suffer from multiple pathological conditions thatcomplicate management and adversely affect outcome, including pulmonary hypertension and chronic obstructive pulmonary disease (COPD). To date, no treatment proved to be fully effective in reducing morbidity and mortality in HFpEF, possibly due to an incomplete understanding of the underlying molecular mechanisms.

RECENT FINDINGS

The emerging view proposes chronic systemic inflammation, leading to endothelial dysfunction and interstitial fibrosis, as a prominent cause of HFpEF, rather than a mere co-existent disease. In the last decade, efforts from pharmaceutical companies attempted to target pharmacologically enzymes which play key roles in systemic and lung inflammation, such as the cyclic nucleotide-degrading enzymes phosphodiesterases (PDEs) and phosphoinositide-3 phosphate kinases (PI3Ks), especially to limit COPD. In this review, we will summarize major successes and drawbacks of hitting these enzymes to tackle inflammation in HFpEF-associated co-morbidities, with a major focus on the results of completed and ongoing clinical trials. Finally, we will discuss the potential of repurposing and/or developing new PDE and PI3K inhibitors for HFpEF therapy.

Signaling through PI3Kγ: a common platform for leukocyte, platelet and cardiovascular stress sensing

The concerted activation of leukocytes and vessels shapes multiple physiological and pathological responses. A large number of these processes shares a common signal transduction platform involving the activation of plasma membrane bound G protein-coupled receptors (GPCRs). This event is usually amplified by the production of different intra-cellular second messenger molecules. Among these mediators, the phosphorylated lipid phosphatidylinositol (3,4,5)-trisphosphate (PIP3) produced by phosphoinositide 3-kinase γ (PI3Kγ) has recently emerged as a crucial signal in both vascular and white blood cells. The generation of mice lacking PI3Kγ showed that the GPCR/PI3Kγ/PIP3 signaling pathway controls diverse immune modulatory and vascular functions like respiratory burst, cell recruitment, mast cell reactivity, platelet aggregation, endothelial activation as well as smooth muscle contractility. The relative specificity of these events suggests that blocking PI3Kγ function might turn out beneficial for diseases like inflammation, allergy, thrombosis, and major cardiovascular disorders like hypertension, thus offering a wide range of therapeutic opportunities.

Investigation of Deteriorated Dissolution of Amorphous Itraconazole: Description of Incompatibility with Magnesium Stearate and Possible Solutions

Disadvantageous crystallization phenomenon of amorphous itraconazole (ITR) occurring in the course of dissolution process was investigated in this work. A perfectly amorphous form (solid dispersion) of the drug was generated by the electroblowing method (with vinylpyrrolidone-vinyl acetate copolymer), and the obtained fibers were formulated into tablets. Incomplete dissolution of the tablets was noticed under the circumstances of the standard dissolution test, after which a precipitated material could be filtered. The filtrate consisted of ITR and stearic acid since no magnesium content was detectable in it. In parallel with dissolution, ITR forms an insoluble associate, stabilized by hydrogen bonding, with stearic acid deriving from magnesium stearate. This is why dissolution curves do not have the plateaus at 100%. Two ways are viable to tackle this issue: change the lubricant (with sodium stearyl fumarate >95% dissolution can be accomplished) or alter the polymer in the solid dispersion to a type being able to form hydrogen bonds with ITR (e.g., hydroxypropyl methylcellulose). This work draws attention to one possible phenomenon that can lead to a deterioration of originally good dissolution of an amorphous solid dispersion.

Mitotic Spindle Assembly and Genomic Stability in Breast Cancer Require PI3K-C2α Scaffolding Function

Proper organization of the mitotic spindle is key to genetic stability, but molecular components of inter-microtubule bridges that crosslink kinetochore fibers (K-fibers) are still largely unknown. Here we identify a kinase-independent function of class II phosphoinositide 3-OH kinase α (PI3K-C2α) acting as limiting scaffold protein organizing clathrin and TACC3 complex crosslinking K-fibers. Downregulation of PI3K-C2α causes spindle alterations, delayed anaphase onset, and aneuploidy, indicating that PI3K-C2α expression is required for genomic stability. Reduced abundance of PI3K-C2α in breast cancer models initially impairs tumor growth but later leads to the convergent evolution of fast-growing clones with mitotic checkpoint defects. As a consequence of altered spindle, loss of PI3K-C2α increases sensitivity to taxane-based therapy in pre-clinical models and in neoadjuvant settings.

Identification of a Potent Phosphoinositide 3-Kinase Pan Inhibitor Displaying a Strategic Carboxylic Acid Group and Development of Its Prodrugs

Activation of the phosphoinositide 3-kinase (PI3K) pathway is a key signaling event in cancer, inflammation, and other proliferative diseases. PI3K inhibitors are already approved for some specific clinical indications, but their systemic on-target toxicity limits their larger use. In particular, whereas toxicity is tolerable in acute treatment of life-threatening diseases, this is less acceptable in chronic conditions. In the past, the strategy to overcome this drawback was to block selected isoforms mainly expressed in leukocytes, but redundancy within the PI3K family members challenges the effectiveness of this approach. On the other hand, decreasing exposure to selected target cells represents a so-far unexplored alternative to circumvent systemic toxicity. In this manuscript, we describe the generation of a library of triazolylquinolones and the development of the first prodrug pan-PI3K inhibitor.