Effect of coinfection with influenza virus and bacteria on host damage / Efecto de la coinfección por virus de la influenza y bacterias en el daño al hospedero

Abstract Background: Influenza virus infection is often complicated by a bacterial infection, with this coinfection causing severe pneumonia. If not timely treated, the disease can cause death. Objective: To demonstrate, in animal models, that coinfection with influenza virus and bacteria that affect the respiratory tract causes multisystemic damage. Method: Six groups of mice were formed: a control group, one infected with the influenza virus, two infected with bacteria: Haemophilus influenzae and Streptococcus pneumoniae, respectively; and two co-infected with influenza virus and Haemophilus influenzae or Streptococcus pneumoniae, respectively. Results: Of the six groups of mice, only the group co-infected with influenza virus and Streptococcus pneumoniae showed damage to thoracic and abdominal organs. A decrease in serum cytokine levels was found in all study groups, which was more pronounced in the co-infected mice. Conclusions: The groups of mice infected with Streptococcus pneumoniae or influenza virus alone showed no damage, which indicates that coexistence of these infections caused the damage in the group of co-infected mice.

Resumen Antecedentes: La infección por el virus de la influenza con frecuencia se complica con una infección bacteriana, coinfección que provoca cuadros graves de neumonía, la cual puede ocasionar la muerte si no es tratada en forma oportuna. Objetivo: Demostrar en modelos animales que la coinfección por el virus de la influenza y bacterias que afectan el tracto respiratorio ocasiona daño multisistémico. Método: Se formaron seis grupos de ratones: un grupo control, uno infectado de virus de la influenza, dos infectados de bacterias: Haemophilus influenzae y Streptococcus pneumoniae, respectivamente; y dos coinfectados de virus de la influenza y Haemophilus influenzae y Streptococcus pneumoniae, respectivamente. Resultados: De los seis grupos de ratones, solo en el grupo coinfectado de virus de la influenza y Streptococcus pneumoniae se observó daño en órganos torácicos y abdominales. En todos los grupos se encontró disminución de los niveles séricos de las citocinas, mayor en los ratones coinfectados. Conclusiones: Los grupos de ratones infectados solo de Streptococcus pneumoniae o el virus de la influenza no presentaron daños, lo cual indica que la coexistencia de estas infecciones fue la que ocasionó el daño en el grupo de ratones coinfectados.

Submission for Special Issue: The Role of Platelet Activation in the Pathophysiology of HIV, Tuberculosis, and Pneumococcal Disease. Bedaquiline Suppresses ADP-Mediated Activation of Human Platelets In Vitro via Interference With Phosphatidylinositol 3-Kinase.

Although bedaquiline has advanced the treatment of multidrug-resistant tuberculosis (TB), concerns remain about the cardiotoxic potential of this agent, albeit by unexplored mechanisms. Accordingly, we have investigated augmentation of the reactivity of human platelets in vitro as a potential mechanism of bedaquiline-mediated cardiotoxicity. Platelet-rich plasma (PRP) or isolated cells prepared from the blood of healthy, adult humans were treated with bedaquiline (0.625-10 µg/ml), followed by activation with adenosine 5'-diphosphate (ADP), thrombin or the thromboxane A2 receptor agonist (U46619). Expression of platelet CD62P (P-selectin), platelet aggregation, Ca2+ fluxes and phosphorylation of Akt1 were measured using flow cytometry, spectrophotometry, fluorescence spectrometry, and by ELISA procedures, respectively. Exposure to bedaquiline caused dose-related inhibition of ADP-activated, but not thrombin- or U46619-activated, expression of CD62P by platelets, achieving statistical significance at a threshold concentration of 5 µg/ml and was paralleled by inhibition of aggregation and Ca2+ mobilization. These ADP-selective inhibitory effects of bedaquiline on platelet activation were mimicked by wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3-K), implicating PI3-K as being a common target of both agents, a contention that was confirmed by the observed inhibitory effects of bedaquiline on the phosphorylation of Akt1 following activation of platelets with ADP. These apparent inhibitory effects of bedaquiline on the activity of PI3-K may result from the secondary cationic amphiphilic properties of this agent. If operative in vivo, these anti-platelet effects of bedaquiline may contribute to ameliorating the risk of TB-associated cardiovascular disease, but this remains to be explored in the clinical setting.

Associação de meningite e pericardite na doença pneumocócica invasiva: um caso raro / Association of meningitis and pericarditis in invasive pneumococcal disease: a rare case

RESUMO Objetivo: Relatar um caso raro de uma criança com meningite associada a pericardite na doença pneumocócica invasiva. Descrição do caso: Este relato descreve uma evolução clínica desfavorável de um lactente feminino de 6 meses de idade, previamente hígido, que apresentou inicialmente sintomas respiratórios e febre. A radiografia de tórax revelou um aumento da área cardíaca sem alterações radiográficas nos pulmões. Após a identificação do derrame pericárdico, o paciente apresentou convulsões e entrou em coma. Pneumonia foi descartada durante a investigação clínica. Contudo, foi identificado Streptococcus pneumoniae nas culturas de líquor e sangue. O exame neurológico inicial foi compatível com morte encefálica, posteriormente confirmada pelo protocolo. Comentários: A pericardite purulenta tornou-se uma complicação rara da doença pneumocócica invasiva desde o advento da terapia antibiótica. Pacientes com pneumonia extensa são primariamente predispostos e, mesmo com tratamento adequado e precoce, estão sujeitos a altas taxas de mortalidade. A associação de meningite pneumocócica e pericardite é incomum e, portanto, de difícil diagnóstico. Por isso, uma alta suspeição diagnóstica é necessária para instituir o tratamento precoce e aumentar a sobrevida.

ABSTRACT Objective: To report a rare case of a child with invasive pneumococcal disease that presented meningitis associated with pericarditis. Case description: This report describes the unfavorable clinical course of a previously healthy 6-months-old female infant who initially presented symptoms of fever and respiratory problems. A chest X-ray revealed an increased cardiac area with no radiographic changes in the lungs. After identifying a pericardial effusion, the patient experienced seizures and went into coma. Pneumonia was excluded as a possibility during the clinical investigation. However, Streptococcus pneumoniae was identified in the cerebrospinal fluid and blood cultures. An initial neurological examination showed that the patient was brain dead, which was then later confirmed according to protocol. Comments: Purulent pericarditis has become a rare complication of invasive pneumococcal disease since the advent of antibiotic therapy. Patients with extensive pneumonia are primarily predisposed and, even with early and adequate treatment, are prone to high mortality rates. The association of pneumococcal meningitis and pericarditis is uncommon, and therefore difficult to diagnose. As such, diagnostic suspicion must be high in order to institute early treatment and increase survival.

Chain pain following cardiac surgery in a 35-year-old man.

CLINICAL INTRODUCTION: A 35-year-old man with multiple cardiovascular risk factors presented with a recent history of fever and acute heart failure. His initial echocardiogram showed evidence of severe aortic regurgitation due to ongoing infective endocarditis. Preoperative coronary angiography revealed no coronary abnormalities. Urgent aortic valve replacement was performed and a 29 mm St Jude mechanical valve was implanted. While blood and resected valvular tissue cultures were negative for bacteria, a PCR-based analysis revealed the presence of penicillin-sensitive Streptococcus pneumoniae. Echocardiographic follow-up study at day 3 showed excellent mechanical valve function with no persistent signs of endocarditis. Eight days after surgery, our patient presented with severe chest pain. The ECG is shown in figure 1A and coronary angiography was performed for diagnostic confirmation (figure 1B-D and online supplementary video 1).DC1SP110.1136/heartjnl-2018-313577.supp1Supplementary file 1 heartjnl;105/3/234/F1F1F1Figure 1(A) 12-lead ECG. (B, C) Selective angiogram of the left main, left anterior descending artery and circumflex artery. (D) Aortic root angiography. QUESTION: Which of the following is most likely the diagnostic?Occlusion of the left anterior descending coronary arteryDissection of the left anterior descending coronary arteryValsalva aneurysm presenting as an acute coronary syndromeLeft anterior descending coronary artery spasmLeft main coronary aneurysm.

Defining the role of pneumococcal neuraminidases and O-glycosidase in pneumococcal haemolytic uraemic syndrome.

The host and bacterial factors that lead to development of pneumococcal haemolytic uraemic syndrome (pHUS) remain poorly defined; however, it is widely believed that pneumococcal exposure of the Thomsen-Friedenreich antigen (T-antigen) on host surfaces is a key step in pathogenesis. Two enzymatic activities encoded by pneumococci determine the level of T-antigen exposed. Neuraminidases cleave terminal sialic acid to expose the T-antigen which is subsequently cleaved by O-glycosidase Eng. While a handful of studies have examined the role of neuraminidases in T-antigen exposure, no studies have addressed the potential role of O-glycosidase. This study used 29 pHUS isolates from the USA and 31 serotype-matched controls. All isolates contained eng, and no significant correlation between enzymatic activity and disease state (pHUS and blood non-pHUS isolates) was observed. A prior study from Taiwan suggested that neuraminidase NanC contributes to the development of pHUS. However, we observed no difference in nanC distribution. Similar to previously published data, we found no significant correlation between neuraminidase activity and disease state. Accurate quantification of these enzymatic activities from bacteria grown in whole blood is currently impossible, but we confirmed that there were no significant correlations between disease state and neuraminidase and O-glycosidase transcript levels after incubation in blood. Genomic sequencing of six pHUS isolates did not identify any genetic elements possibly contributing to haemolytic uraemic syndrome. These findings support the hypothesis that while exposure of T-antigen may be an important step in disease pathogenesis, host factors likely play a substantial role in determining which individuals develop haemolytic uraemic syndrome after pneumococcal invasive disease.

Characteristics and Outcome of Streptococcus pneumoniae Endocarditis in the XXI Century: A Systematic Review of 111 Cases (2000-2013).

Streptococcus pneumoniae is an infrequent cause of severe infectious endocarditis (IE). The aim of our study was to describe the epidemiology, clinical and microbiological characteristics, and outcome of a series of cases of S. pneumoniae IE diagnosed in Spain and in a series of cases published since 2000 in the medical literature. We prospectively collected all cases of IE diagnosed in a multicenter cohort of patients from 27 Spanish hospitals (n = 2539). We also performed a systematic review of the literature since 2000 and retrieved all cases with complete clinical data using a pre-established protocol. Predictors of mortality were identified using a logistic regression model. We collected 111 cases of pneumococcal IE: 24 patients from the Spanish cohort and 87 cases from the literature review. Median age was 51 years, and 23 patients (20.7%) were under 15 years. Men accounted for 64% of patients, and infection was community-acquired in 96.4% of cases. The most important underlying conditions were liver disease (27.9%) and immunosuppression (10.8%). A predisposing heart condition was present in only 18 patients (16.2%). Pneumococcal IE affected a native valve in 93.7% of patients. Left-sided endocarditis predominated (aortic valve 53.2% and mitral valve 40.5%). The microbiological diagnosis was obtained from blood cultures in 84.7% of cases. In the Spanish cohort, nonsusceptibility to penicillin was detected in 4.2%. The most common clinical manifestations included fever (71.2%), a new heart murmur (55%), pneumonia (45.9%), meningitis (40.5%), and Austrian syndrome (26.1%). Cardiac surgery was performed in 47.7% of patients. The in-hospital mortality rate was 20.7%. The multivariate analysis revealed the independent risk factors for mortality to be meningitis (OR, 4.3; 95% CI, 1.4-12.9; P < 0.01). Valve surgery was protective (OR, 0.1; 95% CI, 0.04-0.4; P < 0.01). Streptococcus pneumoniae IE is a community-acquired disease that mainly affects native aortic valves. Half of the cases in the present study had concomitant pneumonia, and a considerable number developed meningitis. Mortality was high, mainly in patients with central nervous system (CNS) involvement. Surgery was protective.

Diagnosis of Streptococcus pneumoniae-associated hemolytic uremic syndrome.

BACKGROUND: Hemolytic uremic syndrome related to pneumococcal infection (P+HUS) can be difficult to diagnose due to the lack of a specific test and the absence of a consensus for definite diagnostic criteria. METHODS: A retrospective study was conducted on the cases that have been considered as P+HUS in the participating centers during the past 10 years. Diagnostic strategy and criteria used for the diagnosis of P+HUS were evaluated and compared with a review of literature data. RESULTS: A total of 17 children were studied. Tests ruling out other causes of HUS were performed in 94% of cases. Direct confirmatory tests for P+HUS were done in a minority of cases as Thomsen-Friedenreich antigen testing using lectin assay were done in only 2 patients (11%). Retrospectively, the diagnosis of P+HUS was confirmed in 28% to 89% of cases depending on the already published criteria used. A literature review focused on the last 15 years confirmed these diagnostic difficulties due to variable definition criteria and bring a new light on the potential usefulness of tests used to reveal T activation in this setting. CONCLUSION: To date, in a context of suspicion of P+HUS, no precise, practical and consensual strategy exists for T-antigen exposure diagnosis. The T-antigen activation test using peanut lectin might be the most appropriate test for a direct diagnosis of P+HUS. A large prospective study is required to confirm this hypothesis. However, before such data are available, its use could be of help when a suspicion of P+HUS is present given the therapeutic impact of such a diagnosis.

Viability and virulence of pneumolysin, pneumococcal surface protein A, and pneumolysin/pneumococcal surface protein A mutants in the ear.

IMPORTANCE: Understanding how pneumococcal proteins affect the pathology of the middle ear and inner ear is important for the development of new approaches to prevent otitis media and its complications. OBJECTIVES: To determine the viability and virulence of Streptococcus pneumoniae mutants deficient in pneumolysin (Ply-) and pneumococcal surface protein A (PspA-) in the chinchilla middle ear. DESIGN: Bullae of chinchillas were inoculated bilaterally with wild-type (Wt), Ply-, PspA-, and Ply-/PspA- strains. Bacterial colony-forming units (CFUs) in middle ear effusions were counted at 48 hours. The CFUs of the PspA- group were also counted at 6 to 36 hours after inoculation. Temporal bone histopathological results were compared. SETTING AND PARTICIPANTS: Twenty-seven chinchillas in an academic research laboratory. EXPOSURE: Chinchilla middle ears were inoculated with S pneumoniae to produce sufficient volumes of effusions and noticeable histopathological changes in the ears. MAIN OUTCOMES AND MEASURES: The CFU counts in the middle ear effusions and histopathological changes were compared to determine the effect of pneumococcal protein mutations on chinchilla ears. RESULTS: At 48 hours, CFUs in middle ears were increased for the Wt and Ply-/PspA- strains, but Ply- remained near inoculum level. No bacteria were detected in the PspA- group. The CFUs of PspA- decreased over time to a low level at 30 to 36 hours. In vitro, PspA- in Todd-Hewitt broth showed an increase in bacterial growth of 2 logs at 43 hours, indicating PspA- susceptibility to host defenses in vivo. The PspA- and Ply- groups had fewer pathologic findings than the Wt or Ply-/PspA- groups. Histopathological analysis showed significant differences in the number of bacteria in the scala tympani in the Wt group compared with the Ply-, PspA-, and Ply-/PspA- groups. The PspA- strain was the least virulent. CONCLUSIONS AND RELEVANCE: The PspA- mutant was much less viable and less virulent in the ear than the Wt, Ply-, and Ply-/PspA- strains. There was no significant attenuation in the viability and virulence of the Ply-/PspA- mutant compared with the Wt or single mutants. The viability and virulence of pneumococcal mutants seemed to be protein and organ specific.

Inhibitory effect of polyunsaturated fatty acids on apoptosis induced by Streptococcus pneumoniae in alveolar macrophages.

BACKGROUND & OBJECTIVES: Apoptosis is considered as a major defense mechanism of the body. Multiple pathogens induce macrophage apoptosis as a mode of immune evasion. In earlier studies, n-3 polyunsaturated fatty acids (PUFA) have been reported to be protective against neuronal apoptosis and neuronal degeneration, seen after spinal cord injury. In this study, we tried to evaluate the role of n-3 polyunsaturated fatty acids on the process of macrophage phagocytic activity and apoptosis in mice. METHODS: Mice were divided into three groups (n=60); Group I was fed on sea cod oil; Group II on flaxseed oil supplementation for 9 wk along with standard laboratory chow diet. Group III was fed on standard diet and served as control. After supplementation, phagocytic and apoptotic (morphological staining: acridine orange plus ethidium bromide; H-33342 plus propidium iodide staining and DNA ladder formation) activities of mouse alveolar macrophages were assessed. RESULTS: Alveolar macrophages (obtained from sea cod oil and flaxseed oil fed group mice) showed significant increase in bacterial uptake as well as intracellular killing (P 0.05) of Streptococcus pneumoniae. Significant decrease (P<0.05) in apoptotic cells was observed among alveolar macrophages from sea cod and flaxseed oil fed mice whereas maximum apoptosis was observed in control alveolar macrophages on interaction with bacteria in vitro which was confirmed by DNA laddering. INTERPRETATION & CONCLUSIONS: These findings suggest that dietary supplementation with n-3 polyunsaturated fatty acids to mice led to enhanced phagocytic capability of their alveolar macrophages as well as provided protection against apoptosis upon challenge with S. pneumoniae.

Nicotinamide nucleotide transhydrogenase (NNT) acts as a novel modulator of macrophage inflammatory responses.

Nicotinamide nucleotide transhydrogenase (NNT) is a mitochondrial redox-driven proton pump that couples the production of NADPH to the mitochondrial metabolic rate. In this study, we demonstrated for the first time that NNT has a significant effect in the modulation of the immune response and host defense against pathogens. We found that NNT mRNA is enriched in immune system-related tissues and regulated during macrophage activation. Overexpression of NNT in a macrophage cell-line resulted in decreased levels of reactive oxygen species (ROS) and nitric oxide upon induction of the macrophage inflammatory responses. These cells failed to fully activate MAPK signaling pathways, resulting in defective secretion of proinflammatory cytokines in response to LPS, and were inefficient in clearance of intracellular bacteria. We have shown that C57BL/6J mice, which have a deletion in the Nnt gene, exhibited greater resistance to acute pulmonary infection with Streptococcus pneumoniae. Macrophages from these mice generated more ROS and established a stronger inflammatory response to this pathogen. Our results demonstrate a novel role for NNT as a regulator of macrophage-mediated inflammatory responses.

Estimation and comparison of EQ-5D health states' utility weights for pneumococcal and human papillomavirus diseases in Argentina, Chile, and the United Kingdom.

OBJECTIVES: To estimate and compare EuroQol instrument (EQ-5D) health states' values for pneumococcal and human papillomavirus (HPV) diseases in Argentina, Chile, and the United Kingdom. METHODS: Twelve vignettes were designed, pilot-tested, and administered to a convenience sample in a cross-sectional design to elicit descriptive EQ-5D state data. Country-specific EQ-5D time-trade-off-based weights were used to map these descriptive health states into local country preference weights. Descriptive analysis is reported and intercountry differences for each condition were compared using repeated measures analysis of variance. RESULTS: Seventy-three subjects completed the survey. Pneumococcal disease-related health states mean values ranged from -0.331 (sepsis, Chile) to 0.727 (auditive sequelae, Argentina). HPV-related conditions ranged from 0.152 (cervical cancer, United Kingdom) to 0.848 (cervical intraepithelial neoplasia 1, Argentina). Chile had consistently the lowest mean values in pneumococcal states and in one HPV state, whereas those of the United Kingdom were the lowest in most HPV states. Argentina had the highest mean values in both diseases. Differences in country-specific values for each health state were statistically (P < 0.001) significant except for six health states in which differences between Chilean and United Kingdom weights were nonsignificant. CONCLUSIONS: Utility values for most conditions differed statistically relevantly among analyzed countries, even though the same health states' descriptive set was valued for each. These results reflect the difference in social weights among different countries, which could be attributed to either different population values or valuation study methodologies. They stress the importance of using local preference weights for context-specific decision making.

Antibody and T-cell responses during acute and convalescent stages of invasive pneumococcal disease.

OBJECTIVE: To understand the pattern of immune responses to pneumococcal proteins during invasive disease as a guide to their development as vaccine candidates. METHODS: The antibody concentration and avidity, as well as frequency of interferon-gamma (IFN-γ)-, interleukin-10 (IL-10)-, and tumor necrosis factor-alpha (TNF-α)-containing CD4+ T-lymphocytes in response to pneumolysin, pneumococcal surface protein A (PspA), and choline-binding protein A (CbpA), during and after invasive pneumococcal disease (IPD) in 20 children were compared to those of 20 healthy matched controls. RESULTS: During the acute phase of IPD, the concentrations of antibodies against these three pneumococcal proteins were lower, whereas the frequencies of IL-10- and TNF-α-producing CD4+ T-cells were higher, compared to values obtained during convalescence and in healthy controls (p < 0.01). In addition, the concentrations of antibodies against the capsular polysaccharides for the serotypes isolated from these patients, were all below the detection level of the assay during both the acute and convalescent phases of IPD. CONCLUSION: These data indicate that the recognition of these antigens by the immune system occurs in variable proportions according to the stage of infection, implying the important role of these in the pathogenesis of IPD, and support their usefulness in vaccine development.

Avances en el desarrollo de las vacunas neumocócicas conjugadas: [revisión] / Update on pneumococcal conjugate vaccines: [review]

El estreptococcus pneumoniae se encuentra entre los mayores patógenos causantes de infecciones invasoras y no invasoras en los dos extremos de la vida: en niños menores de 5 años y en personas mayores de 65 años de edad. Las principales manifestaciones asociadas a infecciones neumocócicas son: neumonía, bacteriemia febril, septicemia, otitis media y meningitis. Esta bacteria es uno de los principales agentes involucrados en la mortalidad infantil, con un estimado de 1000000 de muertes globales por año, en niños menores de 5 años de edad, la mayoría provenientes de países en vías de desarrollo, por lo que es considerada como un serio problema para la salud pública alrededor del mundo. En el 2000 se introdujo al mercado de los Estados Unidos de Norte América, la primera vacuna neumocócica conjugada, que a diferencia de la ya disponible vacuna neumocócica polisacárida, es capaz de proporcionar una respuesta inmune efectiva para la protección de niños menores de 2 años. La eficacia reportada para la vacuna conjugada heptavalente en los ensayos clínicos iniciales fue de un 97.4 por ciento contra la enfermedad neumocócica invasora producida por los serotipos incluidos en la vacuna, 4, 9V, 14, 19F, 23F, 18C y 6B. En la actualidad diferentes entidades regulatorias, incluyendo la Agencia Europea de Medicamentos, EMEA, han autorizado la comercialización de la vacuna conjugada 10-valente, en la que, además de los serotipos descritos para la vacuna 7-valente, se incluyen los serotipos 1, 5 y 7F; de estos diez serotipos, ocho se encuentran conjugados con la proteína transportadora D, un elemento que se encuentra en la porción externa del Haemophilus influenzae. La otra nueva vacuna conjugada que está en fase de análisis por diferentes entidades regulatorias, incluyendo la Administración de Alimentos y Drogas de los Estados Unidos...

Streptococcus pneumoniae is one of the major pathogens causing invasive and non invasive infections in children younger than 5 years as well as in the elderly. Primary clinical syndromesassociated with pneumococcal infections are pneumonia, bacteremia, acute otitis media andmeningitis. This microorganism contributes importantly to morbidity and mortality among children under 5years of age, it is estimated that 1,000, 000 deaths occurs per year in that age range alone, mostly from developing countries, thus becoming a serious public health problem around the globe. In year 2000 the first heptavalent conjugated pneumococcal vaccine was licensed in the United States of America, it differed from the already available polysaccharide pneumococcal vaccine,by its ability to provide an effective immune response for the protection of children under the age of 2. The efficacy of the heptavalent conjugated vaccine reported in initial clinical trials was 97,4% against invasive pneumococcal disease related to vaccine serotypes (4, 9V, 14, 19F, 23F, 18C and 6B). Different health authorities worldwide, including the European Medicines Agency(EMEA) had approved the introduction of a 10-valent formulation which includes all 7 PCV7 serotypes plus serotypes 1, 5 and 7F; 8 serotypes are conjugated with protein D as a novel carrier, an element found in the outer core of the non-typeable Haemophilus influenzae. Another new conjugated vaccine is being assessed by several regulatory entities such as the Food and Drug Administration (FDA) and EMEA and in Chile is already approved. This 13-valent formulation includes the 10 serotypes contained in the 10-valent vaccine plus serotypes 3, 6A and 19A, all conjugated to the carrier protein CRM197. These new formulations pretend to enhance vaccine coverage against S. pneumoniae including the frequent serotypes in developing countries (1 and 5) and emerging serotypes such as serotypes 3, 6A, 17F and 9A after a decade of PCV7 immunization.

IL-7-dependent B lymphocytes are essential for the anti-polysaccharide response and protective immunity to Streptococcus pneumoniae.

Young children are impaired in their response to T cell-independent (TI) Ags, such as pneumococcal polysaccharide (PPS). B lymphopoeisis early in life is IL-7 independent, whereas in adults it is IL-7 dependent. Therefore, we hypothesized that IL-7-driven B lymphopoiesis plays a critical role in promoting Ab responses to TI Ags. Young but not adult mice are impaired in responses to PPS vaccination and to 4-hydroxy-3-nitrophenyl-acetyl-Ficoll, a widely studied model TI Ag, and B1b cells generate Ab responses to these Ags. In this paper, we show that, despite having B1b, B1a, and MZ B cells-all of which are involved in TI responses-young wild-type or adult mice deficient either in IL-7 or in IL-7Ralpha are severely impaired in anti-PPS responses and do not survive Streptococcus pneumoniae challenge, indicating IL-7-dependent B cells are required for TI immunity. Consistent with this, PPS immunization induced a robust TI response in young IL-7 transgenic mice that was comparable to adult wild-type responses. Moreover, immunized young or adult IL-7 transgenic mice were completely resistant to S. pneumoniae challenge. Our data indicate that activating the IL-7 signaling pathway could restore impaired TI responses in the young.

TNF-alpha, IL-1beta, IL-6, and cinc-1 levels in rat brain after meningitis induced by Streptococcus pneumoniae.

Bacterial meningitis caused by Streptococcus pneumoniae is associated with a significant mortality rate and persisting neurologic sequelae, including sensory-motor deficits, seizures, and impairment of learning and memory. The presence of proliferating bacteria within the subarachnoid and ventricular space compartments triggers an intense inflammatory host response at killing the invading microorganism. Proinflammatory mediators released in the process, including tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-1beta, and IL-6, were shown to contribute to the development of brain injury in bacterial meningitis. Thus, the aim of this study was to verify the levels of the TNF-alpha, IL-1beta, IL-6, and CINC-1 in the rat brain after pneumococcal meningitis. The animals underwent a magna cistern tap receiving either 10 microL of sterile saline as a placebo or an equivalent volume of a S. pneumoniae suspension at the concentration of 5x10(9) cfu/mL. The placebo group was killed immediately after the induction and the meningitis group at 0, 6, 12, 24, 48, and 96h after induction. The brains were removed followed by the isolation of the hippocampus and prefrontal cortex for determining TNF-alpha, IL-1beta, IL-6, and CINC-1 levels. In the hippocampus we found increased levels of the TNF-alpha only at 6h (p<0.01; F=3.777); CINC-1 levels increased at 6 and 24h (p<0.001; p<0.05; F=15.05); and IL-6 and IL-1beta levels were not altered. In the prefrontal cortex, the TNF-alpha levels were found to be increased only at 6h (p<0.05; F=4.921); IL-6 (p<0.05; F=11.69) and IL-1beta (p<0.001; F=132.0) levels were found to be increased only at 24h after meningitis induction; and CINC-1 levels were found to be increased at 6, 12, and 24h (p<0.01; p<0.01; p<0.01; F=16.86) after meningitis induction. Our data suggest that cytokine/chemokine levels can be putative biomarkers of brain damage in the first hours of the pneumococcal meningitis.

Age-dependent differences of interleukin-6 activity in cardiac function after burn complicated by sepsis.

Interleukin (IL)-6 is a pleiotropic cytokine that is activated after acute injuries, and plays an important role during aging. We aim to define the role of IL-6 on myocardial dysfunction following a 40% total body surface area burn followed by late (7 days) Streptococcus pneumoniae sepsis (burn plus sepsis) in 2- and 14-month-old wild type and IL-6(-/-) mice. We measured global hemodynamic and cardiac contractile function with left ventricular pressure-volume analysis 24h after sepsis induction, and measured phosphorylated signal transducer and activator of transcription 3 (p-STAT-3), tumor necrosis factor (TNF)-alpha, and IL-1beta in the heart with Western blot analysis. We also measured mRNA expression of IL-6, TNF-alpha, and IL-1beta. Sham injured mice did not manifest any appreciable level of p-STAT-3 or functional deficiencies regardless of age or presence of the IL-6 gene. Burn plus sepsis injury was associated with a significant deterioration of global hemodynamic and cardiac contractile function in WT mice in both age groups. This dysfunction was attenuated by IL-6 deficiency at age 2 months, but accentuated at age 14 months. Aging was associated with an increase in mRNA expression of IL-6 (WT mice), TNF-alpha, and IL-1beta (all mice). At age 14 months, IL-6 deficient mice exhibited a greater TNF-alpha mRNA expression than the wild type mice. We conclude aging is associated with changed cytokine gene transcription, and burn plus sepsis injury further intensifies such gene responses. IL-6 deficiency does not abrogate STAT-3 phosphorylation and it may enhance expression of other inflammatory cytokines. The differential effects of IL-6 deficiency on the cardiac function in young and aging mice cannot be explained by cytokine gene expression alone, and require further studies.

Clinical and immunological features in IgM deficiency.

BACKGROUND: IgM deficiency is a dysgammaglobulinemia characterized by isolated low levels of serum IgM. Patients with IgM deficiency may exhibit various clinical manifestations. However, IgM deficiency still remains to be explored with regard to diagnosis and treatment. METHODS: Through a retrospective chart review, we investigated the clinical and immunological features of 15 symptomatic adult IgM-deficient patients who were referred to our immunology clinics over a 4-year period. RESULTS: The patients were comprised of 6 males and 9 females, with a mean age of 57.2 years. On initial evaluation, 12 patients (80%) presented with susceptibility to infections, 5 (33%) had atopic manifestations such as asthma and allergic rhinitis, 3 (20%) had both infections and atopy, 4 patients (28%) had fibromyalgia-like symptoms, 3 (20%) had autoimmune manifestations, and 1 patient had lymphoma. The mean serum IgM level was 27.4 mg/dl (range 14-39). Impaired specific antibody response to pneumococcal antigens in 5 out of 11 studied patients (45%) appeared to be a notable association. Subtle abnormalities in IgG subclasses, lymphocyte subsets and in vitro proliferative lymphocyte responses were observed. Five patients who were treated with intravenous immunoglobulin responded very well. CONCLUSION: We propose that a thorough immunological evaluation including specific antibody responses be undertaken in patients with IgM deficiency. IgM-deficient patients who present with recurrent/severe infections may benefit from immunoglobulin treatment particularly in the presence of impaired pneumococcal antibody responses.

Hypoglycemia associated with bacteremic pneumococcal infections.

OBJECTIVES: To evaluate the prevalence and associated presentations of hypoglycemia in bacteremic pneumococcal infections, and serotypes of the isolates. METHODS: This was a retrospective study of 70 episodes of pneumococcal bacteremia that occurred in 2004 and 2005. RESULTS: We found hypoglycemia (plasma glucose<3.05 mmol/l)) in six (8.6%) episodes. The patients were three children (mean age 3 years 1 month; range 1 year 5 months-4 years 5 months) and three adults (mean age 73.3 years; range 63-84 years). One child with asplenia and cyanotic heart disease had primary pneumococcal bacteremia. Of the other two children, one had meningitis and the other pneumonia. All the adults had cancer with previous chemotherapy and multilobar pneumonia, which progressed rapidly to respiratory failure. All patients developed their first hypoglycemic episode within two hours after presentation. The average plasma glucose during hypoglycemia was 1.78+/-0.78 mmol/l (range 0.33-2.94 mmol/l). One child and all of the adults died. Serotypes of isolates were those usually associated with severe pneumococcal infection: 6B and 19F in the children; 3, 14, and 23F in the adults. Only the asplenic child had received pneumococcal vaccine. CONCLUSIONS: Hypoglycemia occurred in 8.6% of bacteremic pneumococcal infections and was associated with high mortality and serotypes that cause severe invasive disease. All patients suspected of having septicemia should have their glucose checked to avoid missing hypoglycemia leading to a worsening of their already poor condition.