Pneumococcal neuraminidases A and B both have essential roles during infection of the respiratory tract and sepsis

We examined the role of the neuraminidases NanA and NanB in colonization and infection in the upper and lower respiratory tract by Streptococcus pneumoniae, as well as the role of these neuraminidases in the onset and development of septicemia following both intranasal and intravenous infection. We demonstrated for the first time using outbred MF1 mouse models of infection that both NanA and NanB were essential for the successful colonization and infection of the upper and lower respiratory tract, respectively, as well as pneumococcal survival in nonmucosal sites, such as the blood. Our studies have shown that in vivo a neuraminidase A mutant is cleared from the nasopharynx, trachea, and lungs within 12 h postinfection, while a neuraminidase B mutant persists but does not increase in either the nasopharynx, trachea, or lungs. We also demonstrated both neuraminidase mutants were unable to cause sepsis following intranasal infections. When administered intravenously, however, both mutants survived initially but were unable to persist in the blood beyond 48 h postinfection and were progressively cleared. The work presented here demonstrates the importance of pneumococcal neuraminidase A and for the first time neuraminidase B in the development of upper and lower respiratory tract infection and sepsis.     

Teratoid carcinosarcoma of the paranasal sinuses

Malignant tumours with teratoid or blastomatous features are exceptionally rare in the upper respiratory tract with only 8 documented cases, including the 3 in this report. The tumours occurred in adults aged 27 to 62 yr, and the sites of origin were the ethmoid sinus (4 cases), ethmoid and other paranasal sinuses (2 cases), unspecified sinuses (1 case) and nasopharynx (1 case). The disease was rapidly fatal in 3 cases in which treatment was restricted to surgery and was associated with longer survivals in those given supportive radiotherapy. The tumours are locally aggressive and may invade soft tissues, bone, orbit and cranial cavity. Histologically, the tumours are characterized by a mixture of epithelial and mesenchymal components including cellular elements with immature or embryonal characteristics. These tumours, variously termed malignant teratoma, blastoma, teratocarcinoma or teratoid carcinosarcoma, probably comprise a homogeneous group of neoplasms since their histological and biological features are essentially similar. It is postulated that the tumours develop from primitive embryonic tissues or pluripotential cells that have remained sequestered in the sinonasal tract.     

Anatomy of the nasal cavity in the chinchilla

There is currently great interest worldwide in developing noninvasive methods for the delivery of vaccines for upper respiratory tract diseases, including middle ear infection (otitis media, OM). One such noninvasive approach believed to have great potential for the prevention of diseases of the airway is to deliver vaccines by the intranasal (i.n.) route. Induction of a local, mucosal immune response in the upper respiratory tract, and particularly in the nasopharynx, would be a highly efficacious approach to prevention of OM. The chinchilla is the preferred rodent host for studying OM. However, although the anatomy of the chinchilla vomeronasal organ, inner ear, middle ear and Eustachian tube have been well-studied, to date there have been no reports in the literature of a similar complete analysis of the nasopharynx and nasal cavities of the chinchilla. In order to develop a relevant animal model of i.n. delivery as a potential immunization approach for the prevention of OM and to use these models for preclinical assessments of various vaccine candidates, it was important that we better understand the anatomy of the chinchilla nasal cavities and nasopharynx. Our anatomical studies revealed that the naso- and maxilloturbinates of the chinchilla nasal cavity more closely resemble the simple turbinates found in other rodents rather than the branched or complex turbinates seen in dogs, cats, and rabbits thus facilitating the i.n. delivery of vaccine candidates. The chinchilla nasal mucosa also contains numerous lymphoid aggregates like that of other rodents. Our findings thus suggest that we will be able to deliver i.n. vaccines effectively to chinchillas and that these vaccines will likely be able to induce specific immune responses.     

Upper and lower respiratory tract infection by Streptococcus pneumoniae is affected by pneumolysin deficiency and differences in capsule type

Pneumococci frequently colonize the upper respiratory tract, and these pneumococci are believed to act as a reservoir for infection of the lower respiratory tract and bacteremia. We investigated how the pneumococcal toxin pneumolysin affects the capacity of pneumococci to infect the upper and lower respiratory tract of the mouse. Wild-type Streptococcus pneumoniae serotype 2 and 3 strains, a serotype 2 pneumolysin-deficient mutant, and a serotype 2 mutant with the pneumolysin gene reinserted were used to study differences in colonization and disease. In addition, we also examined a pneumococcal chimeric mutant (capsule type switched from serotype 2 to serotype 3) to gain further insight into the role that capsule plays in nasopharyngeal infection. Absence of pneumolysin was found to be associated with significantly lower numbers of pneumococci in the nasopharynx, trachea, and lungs. Differences in pneumococcal capsule type were found to have significant effects on pneumococcal infection of the nasopharynx, trachea, and lungs. However, it was the combination of capsule type and genetic background that was important, and the influence of this combination varied with the site of infection. For example, in the nasopharynx the wild-type serotype 3 strain and the capsule-switched mutant behaved similarly, whereas in the lungs the mutant that was switched to serotype 3 survived less well than the wild-type serotype 3 strain. The combination of capsule type and genetic background also determined virulence. Thus, the wild-type serotype 3 strain was virulent, whereas the capsule-switched mutant was avirulent.     

Cranial base angulation and growth of the human fetal pharynx

The upper airway controls the mechanisms of breathing, swallowing, and vocalization. Information on its normal ontogenetic associations is therefore crucial for understanding human speech evolution as well as the developmental etiology of speech abnormalities. Of particular interest to evolutionary morphologists is the proposed structural association between the upper airway and the cranial base. The present study aims to elucidate whether cranial base angulation is linked to growth of the upper airway during human fetal life. Forty postmortem human fetuses ranging from 10 to 29 weeks of gestation were imaged with high-resolution magnetic resonance imaging. Measurements of basicranial angle, hyoid depth, hormion height, and pharyngeal area were taken from sagittal images. Results show a significant correlation between the internal and external basicranial angles but the correlation between relative hyoid depth and internal cranial base angle was not significant. Findings show a significant correlation between increases in the size of the oropharynx relative to the nasopharynx and increases in the internal cranial base angle (retroflexion). These findings give limited support (rrank=0.46; P<0.01) for the hypothesis that restructuring of the upper airway underlies basicranial retroflexion during prenatal life.     

Persistence of Diplococcus pneumoniae after Influenza Virus Infection in Macaca mulatta

Exposure of monkeys to aerosols of influenza virus followed later by aerosols of Diplococcus pneumoniae resulted in persistence of the bacteria in the upper respiratory tract for an average of 28 days. Examination of selected tissues for pneumococci revealed that pneumococci were widely disseminated throughout the respiratory tract at 3 and 7 days after exposure, but were cleared from lower respiratory tissues and were found mainly in tonsils, oropharynx, and posterior nasopharynx after 14 days.     

Establishment of streptococci in the upper respiratory tract: longitudinal changes in the mouth and nasopharynx up to 2 years of age

As part of a series of longitudinal studies on the development of the indigenous microflora of the upper respiratory tract, the establishment of streptococci in the oral cavity and nasopharynx and IgA1 protease production by the early streptococcal flora was examined in 50 healthy Caucasian infants at the ages of 2, 6, 12, 18 and 24 months. In the oral cavity, streptococci were found in all infants on every sampling occasion, Streptococcus mitis biovar 1 being the main finding in each age group. S. salivarius and S. mitis biovar 2 reached their highest prevalence during the first year of life, whereas the prevalence of S. oralis and S. sanguis showed no significant increase before 12 months of age. Salivary streptococci mainly consisted of the above-mentioned species during the follow-up period. In contrast to the oral cavity, no stable colonisation pattern was observed for viridans streptococci in the nasopharynx. S. mitis biovar 1 and S. pneumoniae, a traditional respiratory pathogen, were the principal streptococcal species among nasopharyngeal isolates. IgA1 protease production by early streptococci was common in infancy. Among the oral streptococcal microflora, S. mitis biovar 1 (especially during the first year of life) and S. oralis and S. sanguis constituted the main species responsible for this enzyme activity. In the nasopharynx, IgA1 protease was produced by S. mitis biovar 1, S. oralis and S. pneumoniae. In conclusion, streptococcal colonisation differs in these two close habitats in the upper respiratory tract.     

Inhibitory and bactericidal effects of hydrogen peroxide production by Streptococcus pneumoniae on other inhabitants of the upper respiratory tract

An inverse correlation between colonization of the human nasopharynx by Streptococcus pneumoniae and Haemophilus influenzae, both common upper respiratory pathogens, has been reported. Studies were undertaken to determine if either of these organisms produces substances which inhibit growth of the other. Culture supernatants from S. pneumoniae inhibited growth of H. influenzae, whereas culture supernatants from H. influenzae had no effect on the growth of S. pneumoniae. Moreover, coculture of S. pneumoniae and H. influenzae led to a rapid decrease in viable counts of H. influenzae. The addition of purified catalase prevented killing of H. influenzae in coculture experiments, suggesting that hydrogen peroxide may be responsible for this bactericidal activity. H. influenzae was killed by concentrations of hydrogen peroxide similar to that produced by S. pneumoniae. Hydrogen peroxide is produced by the pneumococcus through the action of pyruvate oxidase (SpxB) under conditions of aerobic growth. Both an spxB mutant and a naturally occurring variant of S. pneumoniae, which is downregulated in SpxB expression, were unable to kill H. influenzae. A catalase-reversible inhibitory effect of S. pneumoniae on the growth of the respiratory tract pathogens Moraxella catarrhalis and Neisseria meningitidis was also observed. Elevated hydrogen peroxide production, therefore, may be a means by which S. pneumoniae is able to inhibit a variety of competing organisms in the aerobic environment of the upper respiratory tract.     

Ultrasound investigation of fetal human upper respiratory anatomy

Although the human upper respiratory-upper digestive tract is an area of vital importance, relatively little is known about either the structural or functional changes that occur in the region during the fetal period. While investigations in our laboratory have begun to chart these changes through the use of postmortem materials, in vivo studies have been rarely attempted. This study combines ultrasonography with new applications of video editing to examine aspects of prenatal upper respiratory development. Structures of the fetal upper respiratory-digestive tract and their movements were studied through the use of ultrasonography and detailed frame-by-frame analysis. Twenty-five living fetuses, aged 18-36 weeks gestation, were studied in utero during routine diagnostic ultrasound examination. These real-time linear array sonograms were videotaped during each study. Videotapes were next analyzed for anatomical structures and movement patterns, played back through the ultrasound machine in normal speed, and then examined with a frame-by-frame video editor (FFVE) to identify structures and movements. Still images were photographed directly from the video monitor using a 35 mm camera. Results show that upper respiratory and digestive structures, as well as their movements, could be seen clearly during normal speed and repeat frame-by-frame analysis. Major structures that could be identified in the majority of subjects included trachea in 20 of 25 fetuses (80%); larynx, 76%; pharynx, 76%. Smaller structures were more variable, but were nevertheless observed on both sagittal and coronal section: piriform sinuses, 76%; thyroid cartilage, 36%; cricoid cartilage, 32%; and epiglottis, 16%. Movements of structures could also be seen and were those typically observed in connection with swallowing: fluttering tongue movements, changes in pharyngeal shape, and passage of a bolus via the piriform sinuses to esophagus. Fetal swallows had minimal laryngeal motion. This study represents the first time that the appearance of upper airway and digestive tract structures have been quantified in conjunction with their movements in the living fetus.     

Integration between the cranial boundaries of the nasopharynx and the upper cervical vertebrae in Homo and Pan

The nasopharynx is an important anatomical structure involved in respiration. Its bony boundaries, including the basicranium and upper cervical vertebrae, may be subject to selective pressures and constraints related to respiratory function. Here, we investigate phenotypic integration, or covariation, between the face, the basicranial boundaries of the nasopharynx, and the atlas and axis to understand constraints affecting these structures. We collected three-dimensional coordinate data from a sample of 80 humans and 44 chimpanzees, and used two-block partial least squares to assess RV (a multivariate generalization of Pearson's r²), r_PLS, the covariance ratio, and effect size for integration among structures. We find that integration is significant among some of these structures, and that integration between the basicranial nasopharynx and vertebrae and between the face and vertebrae is likely independent. We also find divergences in the pattern of integration between humans and chimpanzees suggesting greater constraints among the human face and nasopharynx, which we suggest are linked to divergent developmental trajectories in the two taxa. Evolutionary changes in human basicranial anatomy, coupled with human-like developmental trajectories, may have required that the face grow to compensate any variation in nasopharyngeal structure. However, we were unable to determine whether the nasopharynx or the face is more strongly integrated with the vertebrae, and therefore whether respiration or biomechanical considerations related to positional behavior may be more strongly tied to vertebral evolution. Future work should focus on greater sample sizes, soft tissue structures, and more diverse taxa to further clarify these findings.     

RSV-induced bronchiolitis but not upper respiratory tract infection is accompanied by an increased nasal IL-18 response

The aim of this study was to investigate potential differences in the local nasal immune response between bronchiolitis and upper respiratory tract infection induced by respiratory syncytial virus (RSV). Nasal brush samples were obtained from 14 infants with RSV bronchiolitis and from 8 infants with RSV upper respiratory tract infection. The samples were taken during infection (acute phase) and 2-4 weeks later (convalescent phase). Cytospin preparations were stained immunohistochemically for T cells, macrophages, and eosinophils. Staining also took place for intercellular adhesion molecule-1 (ICAM-1), T-helper 1 (Th1)-like (interleukin-12 [IL-12], interferon-gamma [IFN-gamma]), Th2-like (IL-4, IL-10), and proinflammatory cytokines (IL-6, IL-8, IL-18). During both RSV-induced bronchiolitis and upper respiratory tract infection, cellular inflammation was observed. This was characterised by an increase in the numbers of nasal macrophages, which tended to be higher in bronchiolitis than in upper respiratory tract infection. Numbers of T lymphocytes and ICAM-1 positive cells increased during both bronchiolitis and upper respiratory tract infection. There were no differences between numbers in the groups. Interestingly, a distinct nasal proinflammatory cytokine response was observed in RSV-induced bronchiolitis. This is characterised by an increase in the number of IL-18 positive cells. This increase is specific for bronchiolitis, as a similar increase could not be detected in RSV-induced upper respiratory tract infection. Numbers of IL-6 and IL-12 positive cells were higher in both bronchiolitis and upper respiratory tract infection, and there were no differences between the groups. By contrast, the number of IL-8, IFN-gamma, IL-4, and IL-10-positive cells remained constant. In conclusion, clear differences were found in nasal immune responses of children with RSV-induced upper respiratory tract infection or bronchiolitis. The induction of a strong IL-18 response was typical for bronchiolitis, as this could not be observed in RSV-induced upper respiratory tract infection, and could explain the eosinophilia that is observed frequently during bronchiolitis.     

呼吸道内颗粒物沉积的数值模拟

目的通过数值模拟方法研究人呼吸过程中吸入的颗粒物在呼吸道内的沉积规律及其影响因素。方法建立正常人呼吸道三维数值模型,模拟吸气过程中气流在呼吸道内的分布规律。在鼻孔或口等气流入口处释放颗粒,模拟悬浮颗粒物随着吸入气流在呼吸道内的沉积过程。同时改变颗粒物直径、密度、呼吸气流速率等参数,通过对比分析,研究颗粒物在呼吸道内沉积的影响因素。结果颗粒物在呼吸道内主要沉积在鼻阈、固有鼻腔气道中部、鼻咽部以及支气管内壁,并且颗粒物的沉积率随着其直径、密度、呼吸气流速率的增大而增加,几个参数对沉积率的影响程度也不相同。结论颗粒物在呼吸道内主要沉积在气道几何形状复杂或者气道走向剧烈改变的位置,颗粒物的直径、密度、呼吸气流速率均会影响到其在呼吸道内的沉积率。研究结果可为空气污染引发呼吸道疾病风险的临床评估提供数值依据。     

Is IgA nephropathy induced by hyperproduction of interferon-alpha?

The frequent occurrence of tonsillitis or upper respiratory tract infections preceeding exacerbations of haematuria in IgA nephropathy (IgAN) suggests a relationship to the pathogenesis. Since it has been shown that release of type I interferon (IFN-alpha) can promote the release of BAFF which aids maturation of B lymphocytes, and IFN-alpha is released as part of innate immunity to pathogens of the upper respiratory tract, it is suggested than IFN-alpha may trigger the pathogenic process of IgAN. How cells in the tonsils contribute and whether Il-6 formation in the lungs also helps development of Th.2 lymphocytes are to be considered.     

Animal models of virus-induced chronic airway disease

There is increasing evidence that experiencing viral wheezing illnesses early in life, especially in conjunction with allergic sensitization, is an important risk factor for the onset of asthma. In this review, the potential advantages and disadvantages of using rodent models of virus-induced chronic airway dysfunction to investigate the mechanisms by which early-life viral respiratory tract infections could initiate a process leading to chronic airway dysfunction and the asthmatic phenotype are discussed. The potential usefulness of rodent models for elucidating the viral, host, environmental, and developmental factors that might influence these processes is emphasized. There is a need for the continued development of rodent models of early-life viral respiratory tract infections that include the development of chronic airway dysfunction, the capacity to add components of allergic sensitization and allergic airway inflammation, and the ability to address both immunologic and physiologic consequences. Investigation of these rodent models should complement the research from pediatric cohort studies and begin to bring us closer to understanding the role of viral respiratory tract infections in the inception of childhood asthma.     

Sialylated glycans and mucins in the lacrimal gland and eyelid of man and pig. Potential receptors for pathogenic microorganisms

The conjunctiva of the eyelid is coated by secretion products from the lacrimal and eyelid glands, and by mucins produced by conjunctival goblet cells, which together form a glycoprotein-rich layer that lubricates and protects the surface of the eye. However, these ocular carbohydrates may also act as adhesives for viruses and bacteria and thereby facilitate their colonization. This paper provides histochemical demonstration of the in situ localization of such carbohydrate receptors in the form of sialylated glycans and mucins in the lacrimal and eyelid glands and conjunctiva from both humans and pigs. The pig is included in this study because viruses of swine origin may be capable of transmission to humans. We found that the human and pig ocular surfaces contain receptors for bacteria and viruses in the form of mucins (both membrane bound and secreted) and carbohydrates terminating in Sialylα2-6Gal epitopes and to a lesser degree in Sialylα2-3Gal. The glycosylation of the human soft palate could indicate a mucinous route for the spread of microorganisms from the eye via the nasolacrimal duct to the nasopharynx and thus to the upper part of the respiratory tract.     

The evaluation of the degree of attenuation of cold-adapted influenza A virus strains in CBA-strain mouse and Syrian hamster models]

The pattern of the infectious process induced by the epidemic A/Leningrad/134/57 (H2N2) virus and its cold-adapted (CA) variants in CBA mice and Syrian hamsters was studied. The strains under study inoculated into the animals under a mild ether anesthesia differed by virulence, reproductive capacity in the nasopharynx, trachea and lungs, as well as by the isolation rate from extrarespiratory organs of both mice and hamsters. Upon intranasal inoculation of mice without anesthesia, the CA strains were found to be incapable of dissemination into the lower parts of the respiratory tract with distinguished these viruses from the original epidemic strain A/Leningrad/134/57 as well as from the mouse-adapted strain A/PR/8/34 (H1N1) used as control. The experimental results show that both models are suitable for laboratory evaluation of the attenuation degree of human influenza viruses.     

Contributions of pneumolysin, pneumococcal surface protein A (PspA), and PspC to pathogenicity of Streptococcus pneumoniae D39 in a mouse model

Successful colonization of the upper respiratory tract by Streptococcus pneumoniae is an essential first step in the pathogenesis of pneumococcal disease. However, the bacterial and host factors that provoke the progression from asymptomatic colonization to invasive disease are yet to be fully defined. In this study, we investigated the effects of single and combined mutations in genes encoding pneumolysin (Ply), pneumococcal surface protein A (PspA), and pneumococcal surface protein C (PspC, also known as choline-binding protein A) on the pathogenicity of Streptococcus pneumoniae serotype 2 (D39) in mice. Following intranasal challenge with D39, stable colonization of the nasopharynx was maintained over a 7-day period at a level of approximately 10(5) bacteria per mouse. The abilities of the mutant deficient in PspA to colonize the nasopharynx and to cause lung infection and bacteremia were significantly reduced. Likewise, the PspC mutant and, to a lesser extent, the Ply mutant also had reduced abilities to colonize the nasopharynx. As expected, the double mutants colonized less well than the parent to various degrees and had difficulty translocating to the lungs and blood. A significant additive attenuation was observed for the double and triple mutants in pneumonia and systemic disease models. Surprisingly, the colonization profile of the derivative lacking all three proteins was similar to that of the wild type, indicating virulence gene compensation. These findings further demonstrate that the mechanism of pneumococcal pathogenesis is highly complex and multifactorial but ascribes a role for each of these virulence proteins, alone or in combination, in the process.     

人体上呼吸道流体动力学研究进展

随着科学技术的迅猛发展以及大气环境的不断恶化,人体上呼吸道流体动力学的研究越来越受到人们的关注.归纳了人体上呼吸道中流体动力学研究方法,总结了国内外学者所构建的人体上呼吸道力学模型,分析了人体上呼吸道气流运动组织特性和颗粒输运沉积规律的研究现状,展望了人体上呼吸道流体动力学的发展趋势.     

Tissue resident memory T cells in the respiratory tract

Owing to their capacity to rapidly spread across the population, airborne pathogens represent a significant risk to global health. Indeed, several of the past major global pandemics have been instigated by respiratory pathogens. A greater understanding of the immune cells tasked with protecting the airways from infection will allow for the development of strategies that curb the spread and impact of these airborne diseases. A specific subset of memory T-cell resident in both the upper and lower respiratory tract, termed tissue-resident memory (Trm), have been shown to play an instrumental role in local immune responses against a wide breadth of both viral and bacterial infections. In this review, we discuss factors that influence respiratory tract Trm development, longevity, and immune surveillance and explore vaccination regimes that harness these cells, such approaches represent exciting new strategies that may be utilized to tackle the next global pandemic.