Ricardo J. José

Protection against Streptococcus pneumoniae lung infection after nasopharyngeal colonization requires both humoral and cellular immune responses

Streptococcus pneumoniae is a common cause of pneumonia and infective exacerbations of chronic lung disease, yet there are few data on how adaptive immunity can specifically prevent S. pneumoniae lung infection. We have used a murine model of nasopharyngeal colonization by the serotype 19F S. pneumoniae strain EF3030 followed by lung infection to investigate whether colonization protects against subsequent lung infection and the mechanisms involved. EF3030 colonization induced systemic and local immunoglobulin G against a limited number of S. pneumoniae protein antigens rather than capsular polysaccharide. During lung infection, previously colonized mice had increased early cytokine responses and neutrophil recruitment and reduced bacterial colony-forming units in the lungs and bronchoalveolar lavage fluid compared with control mice. Colonization-induced protection was lost when experiments were repeated in B-cell- or neutrophil-deficient mice. Furthermore, the improved interleukin (IL)-17 response to infection in previously colonized mice was abolished by depletion of CD4+ cells, and prior colonization did not protect against lung infection in mice depleted of CD4+ cells or IL17. Together these data show that naturally acquired protective immunity to S. pneumoniae lung infection requires both humoral and cell-mediated immune responses, providing a template for the design of improved vaccines that can specifically prevent pneumonia or acute bronchitis.

Macrophage Migration Inhibitory Factor–CXCR4 Is the Dominant Chemotactic Axis in Human Mesenchymal Stem Cell Recruitment to Tumors

Mesenchymal stromal cells (MSCs) are inherently tumor homing and can be isolated, expanded, and transduced, making them viable candidates for cell therapy. This tumor tropism has been used to deliver anticancer therapies to various tumor models. In this study, we sought to discover which molecules are the key effectors of human MSC tumor homing in vitro and using an in vivo murine model. In this study, we discover a novel role for macrophage migration inhibitory factor (MIF) as the key director of MSC migration and infiltration toward tumor cells. We have shown this major role for MIF using in vitro migration and invasion assays, in presence of different receptor inhibitors and achieving a drastic decrease in both processes using MIF inhibitor. Additionally, we demonstrate physical interaction between MIF and three receptors: CXCR2, CXCR4, and CD74. CXCR4 is the dominant receptor used by MIF in the homing tumor context, although some signaling is observed through CXCR2. We demonstrate downstream activation of the MAPK pathway necessary for tumor homing. Importantly, we show that knockdown of either CXCR4 or MIF abrogates MSC homing to tumors in an in vivo pulmonary metastasis model, confirming the in vitro two-dimensional and three-dimensional assays. This improved understanding of MSC tumor tropism will further enable development of novel cellular therapies for cancers.

Sedation for flexible bronchoscopy: current and emerging evidence

Flexible bronchoscopy is commonly performed by respiratory physicians and is the gold standard for directly visualising the airways, allowing for numerous diagnostic and therapeutic interventions. With the widespread use of flexible bronchoscopy and the evolution of interventional bronchoscopy with more complex and longer procedures, physicians are placing increasing importance on the use of sedation as a necessary adjunct to topical anaesthesia. There is no standardised practice for the use of sedation in bronchoscopy with a good deal of variation among physicians regarding the use of pre-procedure medication and pharmacological sedatives. In addition, there is ongoing debate and controversy about proceduralist-administered versus anaesthetist-administered sedation whilst at the same time there is a growing body of evidence that nonanaesthetist administered sedation is safe and cost-effective. In this review we summarise the evidence for the use of sedation as an adjunct to topical anaesthesia in bronchoscopy and provide the clinician with up-to-date concise guidance for the use of pharmacological sedatives in bronchoscopy and future directions for sedation in the bronchoscopy suite.

Regulation of Neutrophilic Inflammation by Proteinase-Activated Receptor 1 during Bacterial Pulmonary Infection

Neutrophils are key effector cells of the innate immune response to pathogenic bacteria, but excessive neutrophilic inflammation can be associated with bystander tissue damage. The mechanisms responsible for neutrophil recruitment to the lungs during bacterial pneumonia are poorly defined. In this study, we focus on the potential role of the major high-affinity thrombin receptor, proteinase-activated receptor 1 (PAR-1), during the development of pneumonia to the common lung pathogen Streptococcus pneumoniae. Our studies demonstrate that neutrophils were indispensable for controlling S. pneumoniae outgrowth but contributed to alveolar barrier disruption. We further report that intra-alveolar coagulation (bronchoalveolar lavage fluid thrombin–antithrombin complex levels) and PAR-1 immunostaining were increased in this model of bacterial lung infection. Functional studies using the most clinically advanced PAR-1 antagonist, SCH530348, revealed a key contribution for PAR-1 signaling in influencing neutrophil recruitment to lung airspaces in response to both an invasive and noninvasive strain of S. pneumoniae (D39 and EF3030) but that PAR-1 antagonism did not impair the ability of the host to control bacterial outgrowth. PAR-1 antagonist treatment significantly decreased pulmonary levels of IL-1β, CXCL1, CCL2, and CCL7 and attenuated alveolar leak. Ab neutralization studies further demonstrated a nonredundant role for IL-1β, CXCL1, and CCL7 in mediating neutrophil recruitment in response to S. pneumoniae infection. Taken together, these data demonstrate a key role for PAR-1 during S. pneumoniae lung infection that is mediated, at least in part, by influencing multiple downstream inflammatory mediators.

Naturally Acquired Human Immunity to Pneumococcus Is Dependent on Antibody to Protein Antigens

Naturally acquired immunity against invasive pneumococcal disease (IPD) is thought to be dependent on anti-capsular antibody. However nasopharyngeal colonisation by Streptococcus pneumoniae also induces antibody to protein antigens that could be protective. We have used human intravenous immunoglobulin preparation (IVIG), representing natural IgG responses to S. pneumoniae, to identify the classes of antigens that are functionally relevant for immunity to IPD. IgG in IVIG recognised capsular antigen and multiple S. pneumoniae protein antigens, with highly conserved patterns between different geographical sources of pooled human IgG. Incubation of S. pneumoniae in IVIG resulted in IgG binding to the bacteria, formation of bacterial aggregates, and enhanced phagocytosis even for unencapsulated S. pneumoniae strains, demonstrating the capsule was unlikely to be the dominant protective antigen. IgG binding to S. pneumoniae incubated in IVIG was reduced after partial chemical or genetic removal of bacterial surface proteins, and increased against a Streptococcus mitis strain expressing the S. pneumoniae protein PspC. In contrast, depletion of type-specific capsular antibody from IVIG did not affect IgG binding, opsonophagocytosis, or protection by passive vaccination against IPD in murine models. These results demonstrate that naturally acquired protection against IPD largely depends on antibody to protein antigens rather than the capsule.

Proteinase-activated receptors in fibroproliferative lung disease

The coagulation cascade plays a central role in the pathogenesis of fibroproliferative lung diseases such as the acute respiratory distress syndrome (ARDS) and idiopathic pulmonary fibrosis (IPF) through multifaceted effects on haemostasis, inflammation and tissue repair. However, targeting the coagulation cascade using traditional anticoagulant approaches has not resulted in improved outcomes for these patients. The cellular effects of the coagulation cascade are mediated via a family of four proteinase-activated receptors (PAR1–4). PARs are G protein-coupled receptors that have a unique method of activation involving proteolytic cleavage. They play key roles in mediating the interplay between coagulation and inflammation and tissue repair and fibrosis. Current evidence suggests a central role for PAR1 and PAR2 in influencing these responses, although data from animal models suggest that their contribution is highly dependent on both the nature of the insult and disease status. Nonetheless, these receptors may represent important targets in conditions associated with uncontrolled coagulation signalling responses including IPF, ARDS, asthma and chronic obstructive pulmonary disease.

Community-acquired pneumonia.

Purpose of review Community-acquired pneumonia (CAP) is the most common infectious disease cause of death. We summarize recent findings regarding the epidemiology of CAP in adults, efficacy of vaccines against Streptococcus pneumoniae, diagnostics, and discuss the current controversy between CAP and healthcare-associated pneumonia (HCAP). Recent findings The emergence of the Middle East respiratory syndrome coronavirus and the avian influenza A strain H7N9 are of concern but still these are infrequent causes of CAP. Recent data indicate that vaccinating children also protects adults against CAP by generating significant herd immunity, and that the conjugated pneumococcal vaccine in adults may offer some efficacy in preventing CAP caused by vaccine serotypes. The immunochromotagraphic urinary antigen test has improved the diagnostic yield for the aetiology of CAP, and initial data demonstrate that a novel multiplex urinary antigen test will further increase the sensitivity for detection of S. pneumoniae. There has been significant concern that a relatively recently described pneumonia category, HCAP, requires empirical treatment for potentially multidrug-resistant organisms (MDRO). However, new evidence shows that (at least in Europe) pneumonia caused by MDRO remains uncommon even in HCAP category patients. Summary CAP remains a major cause of morbidity and mortality. Advances in vaccination and diagnosis should help reduce the amount of disease due to S. pneumoniae, the commonest cause of CAP. Outside of the United States, MDRO are relatively uncommon causes of CAP, and the increased mortality of HCAP category patients seems to be related to their comorbidities and age rather than microbial aetiology.

Enhanced inflammation in aged mice following infection with Streptococcus pneumoniae is associated with decreased IL-10 and augmented chemokine production

Streptococcus pneumoniae is the most common cause of severe pneumonia in the elderly. However, the impact of aging on the innate inflammatory response to pneumococci is poorly defined. We compared the innate immune response in old vs. young adult mice following infection with S. pneumoniae. The accumulation of neutrophils recovered from bronchoalveolar lavage fluid and lung homogenates was increased in aged compared with young adult mice, although bacterial outgrowth was similar in both age groups, as were markers of microvascular leak. Aged mice had similar levels of IL-1β, TNF, IFN-γ, IL-17, and granulocyte colony-stimulating factor following S. pneumoniae infection, compared with young mice, but increased levels of the chemokines CXCL9, CXCL12, CCL3, CCL4, CCL5, CCL11, and CCL17. Moreover, levels of IL-10 were significantly lower in aged animals. Neutralization of IL-10 in infected young mice was associated with increased neutrophil recruitment but no decrease in bacterial outgrowth. Furthermore, IL-10 neutralization resulted in increased levels of CCL3, CCL5, and CXCL10. We conclude that aging is associated with enhanced inflammatory responses following S. pneumoniae infection as a result of a compromised immunomodulatory cytokine response.

Anesthesia for bronchoscopy.

Purpose of review To discuss the recent advances in sedation and anesthesia for the practice of both flexible and rigid bronchoscopy, which are increasingly performed outside of the operating room by interventional pulmonologists and thoracic surgeons. Recent findings Studies have recently documented the advantages of pharmacological sedatives and anesthetics for use in bronchoscopy. In particular, we review the increasing body of literature highlighting the advantages and benefits of propofol anesthesia for both flexible and rigid bronchoscopy. Summary As our practice expands, relocation of appropriately triaged pulmonary interventional procedures including rigid bronchoscopy that were previously assigned to a traditional operating room setting improves provider flexibility, presents more cost-effective options while maintaining patient safety and satisfaction and reducing the time to recovery. Anesthesia practice has, therefore, shifted to caring for these sick patients outside the operating room and increasingly cooperation between anesthesiologist and proceduralist is required.

Protective Role of the Capsule and Impact of Serotype 4 Switching on Streptococcus mitis

ABSTRACT The polysaccharide capsule surrounding Streptococcus pneumoniae is essential for virulence. Recently, Streptococcus mitis, a human commensal and a close relative of S. pneumoniae, was also shown to have a capsule. In this study, the S. mitis type strain switched capsule by acquisition of the serotype 4 capsule locus of S. pneumoniae TIGR4, following induction of competence for natural transformation. Comparison of the wild type with the capsule-switching mutant and with a capsule deletion mutant showed that the capsule protected S. mitis against phagocytosis by RAW 264.7 macrophages. This effect was enhanced in the S. mitis strain expressing the S. pneumoniae capsule, which showed, in addition, increased resistance against early clearance in a mouse model of lung infection. Expression of both capsules also favored survival in human blood, and the effect was again more pronounced for the capsule-switching mutant. S. mitis survival in horse blood or in a mouse model of bacteremia was not significantly different between the wild type and the mutant strains. In all models, S. pneumoniae TIGR4 showed higher rates of survival than the S. mitis type strain or the capsule-switching mutant, except in the lung model, in which significant differences between S. pneumoniae TIGR4 and the capsule-switching mutant were not observed. Thus, we identified conditions that showed a protective function for the capsule in S. mitis. Under such conditions, S. mitis resistance to clearance could be enhanced by capsule switching to serotype 4, but it was enhanced to levels lower than those for the virulent strain S. pneumoniae TIGR4.