Streptococcus pneumoniae is a complex Gram-positive bacterium comprising over 90 different serotypes and is a major cause of pneumonia. Susceptibility to S. pneumoniae is remarkably age-related being greatest in children under 5 years old and adults over 65. Whilst the immaturity of the immune system is largely responsible for poor immunity in the former, the underlying causes of susceptibility in older adults is complex. Immunity to S. pneumoniae is mediated predominantly through the inflammatory response in the nasopharyngeal mucosa recruiting phagocytes (neutrophils and monocyte/macrophages) which recognise the pathogen via TLR2 and ingest and kill the bacteria, with the induction of Th17 cells being required to maintain neutrophil recruitment and ensure clearance of the infection. In this review we discuss the impact of ageing upon these aspects of immunity to S. pneumoniae, as well as age-related changes to the serotypes present in the adult nasopharyngeal tract which could further influence susceptibility to infection.

Pancreatic ductal adenocarcinoma (PDAC) is predicted to become the second leading cause of cancer‐related deaths in the United States by 2020, due in part to innate resistance to widely used chemotherapeutic agents and limited knowledge about key molecular factors that drive tumor aggression. We previously reported a novel negative prognostic biomarker, keratin 17 (K17), whose overexpression in cancer results in shortened patient survival. In this study, we aimed to determine the predictive value of K17 and explore the therapeutic vulnerability in K17‐expressing PDAC, using an unbiased high‐throughput drug screen. Patient‐derived data analysis showed that K17 expression correlates with resistance to gemcitabine (Gem). In multiple in vitro and in vivo models of PDAC, spanning human and murine PDAC cells, and orthotopic xenografts, we determined that the expression of K17 results in a more than twofold increase in resistance to Gem and 5‐fluorouracil, key components of current standard‐of‐care chemotherapeutic regimens. Furthermore, through an unbiased drug screen, we discovered that podophyllotoxin (PPT), a microtubule inhibitor, showed significantly higher sensitivity in K17‐positive compared to K17‐negative PDAC cell lines and animal models. In the clinic, another microtubule inhibitor, paclitaxel (PTX), is used in combination with Gem as a first‐line chemotherapeutic regimen for PDAC. Surprisingly, we found that when combined with Gem, PPT, but not PTX, was synergistic in inhibiting the viability of K17‐expressing PDAC cells. Importantly, in preclinical models, PPT in combination with Gem effectively decreased tumor growth and enhanced the survival of mice bearing K17‐expressing tumors. This provides evidence that PPT and its derivatives could potentially be combined with Gem to enhance treatment efficacy for the ~ 50% of PDACs that express high levels of K17. In summary, we reported that K17 is a novel target for developing a biomarker‐based personalized treatment for PDAC.

Keratin 17 (K17), an oncofetal intermediate filament protein, is one of the most abundantly expressed proteins in pancreatic ductal adenocarcinomas (PDACs) of the most aggressive molecular subtype. The mechanistic roles of this protein in malignancy, however, are largely unexplored. Here we show that K17 expression and disassembly enhances tumor growth and metastatic potential and shortens survival. Using mass spectrometry in K17 isolated from patient’s tumors, we identified a hotspot phosphorylation site in serines 10-13. Site-mutagenesis revealed that phosphorylation of this hotspot is sufficient to disassemble K17 and promote its nuclear translocation. In silico and pharmacologic inhibition studies uncovered the role of the PKC/MEK/RSK pathway in the phosphorylation and disassembly of K17. Murine models bearing tumors expressing phosphomimetic mutations at the serine hotspot displayed enhanced metastases, compared to mice bearing tumors expressing wild-type K17 or phosphorylation-resistant K17. Lastly, we found that detergent-soluble nuclear K17 promotes the expression of metastasis promoting genes in both patient and murine tumors. These results suggest that phosphorylation at specific serines is sufficient to promote pancreatic cancer metastasis and shorter survival, and that these sites could provide novel, druggable therapeutic domains to enhance PDAC patient survival.

Título da Dissertação: Ação do imunomodulador P-MAPA sobre o sistema complemento e receptores do tipo Toll em modelo de inflamação induzida por lipopolissacarídeo.