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Background. Streptococcus pneumoniae is the most common causative organism in community-acquired pneumonia. Pneumococci that try to invade the lower airways are recognized by innate immune cells through pattern recognition receptors, including Toll-like receptors 2, 4, and 9. Interleukin 1 (IL-1) receptor-associated kinase (IRAK)-M is a proximal inhibitor of Toll-like receptor signaling. Methods. To determine the role of IRAK-M in host defense during pneumococcal pneumonia, IRAK-M- deficient and wild-type mice were intranasally infected with S. pneumoniae. Results. IRAK-M-deficient mice demonstrated a reduced lethality after infection with S. pneumoniae via the airways. Whereas bacterial burdens were similar in IRAK-M-deficient and wild-type mice early (3 hours) after infection, from 24 hours onward the number of pneumococci recovered from lungs and distant body sites were 10-100-fold lower in the former mouse strain. The diminished bacterial growth and dissemination in IRAK-M-deficient mice were preceded by an increased early influx of neutrophils into lung tissue and elevated pulmonary levels of IL-1[beta] and CXCL1. IRAK-M deficiency did not influence bacterial growth after intravenous administration of S. pneumoniae. Conclusions. These data suggest that IRAK-M impairs host defense during pneumococcal pneumonia at the primary site of infection at least in part by inhibiting the early immune response. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Pneumonia is characterized by an acute inflammatory response in the lung, which is frequently associated with changes in coagulation and fibrinolysis in the bronchoalveolar space. Here, we compared the effects of lipoteichoic acid (LTA), a major cell wall component of Gram-positive bacteria, and lipopolysaccharide (LPS), in the human bronchoalveolar space. DESIGN: Controlled in vivo volunteer study. SETTING: Clinical research unit. SUBJECTS: Twenty-three healthy nonsmoking male volunteers. INTERVENTIONS: Sterile saline was instilled into a lung subsegment followed by bronchoscopic instillation of either LTA (Staphylococcus aureus, at a dose of 4, 20, or 100 ng/kg body weight) or LPS (Escherichia coli, 4 ng/kg body weight) into the contralateral lung. Bronchoalveolar lavage fluid was obtained 6 hours thereafter. MEASUREMENTS AND MAIN RESULTS: Bronchial instillation of LTA- or LPS-activated bronchoalveolar coagulation, as reflected by increases in the levels of thrombin-antithrombin complexes, d-dimer, and soluble tissue factor. Concurrently, LTA and LPS inhibited anticoagulant mechanisms, as indicated by reductions in antithrombin, Protein C, and Activated Protein C concentrations together with elevated levels of soluble thrombomodulin. Both LTA and LPS administration was associated with an inhibition of pulmonary fibrinolysis, as measured by a reduction in plasminogen activator activity and elevated levels of plasminogen activator inhibitor type I. CONCLUSIONS: This study is the first to describe the effects of LTA on hemostasis in humans, demonstrating that LTA induces similar changes in the human bronchoalveolar space as LPS, characterized by activation of coagulation with concurrent inhibition of anticoagulant and fibrinolytic pathways. [ABSTRACT FROM AUTHOR]

Objectives: Previous research has suggested beneficial heterologous effects of the Bacillus Calmette-Guérin (BCG) vaccine on non-mycobacterial infections and other immune-mediated diseases. During the COVID-19 pandemic, randomized controlled trials BCG-PRIME (n = 5349) and BCG-CORONA-ELDERLY (n = 1907) investigated the impact of BCG on SARS-CoV-2 infections in older individuals. We extended the follow-up in these studies by one year (BCG-Long Term study), to assess the overall effects of BCG vaccination on infectious and immune-mediated diseases in individuals aged over 60., Methods: Prior participants were invited to complete a one-year follow-up survey after their completion of the original trial. Data on vaccinations, hospital admissions, infectious episodes, and new medical diagnoses were collected and compared between BCG- and placebo-vaccinated participants. Variables of interest were combined with the previous trial databases and analyzed using relative risks (RR) and an adjusted Cox regression model accounting for participation probability., Results: The response in the follow-up survey was 60%, including 4238 individuals in the final analysis (2317 had received BCG and 1921 placebo). Incidence and severity of infectious diseases and other diagnoses, including cardiovascular diseases and cancer, did not differ between the groups. The proportion of individuals hospitalized for cardiac arrhythmias after BCG was two-fold higher than reported after placebo (1.6% versus 0.8%, RR 2.0 (95% confidence interval 1.1-3.6)). Cardiac arrhythmia-related hospitalizations were primarily due to exacerbation of pre-existing arrhythmias., Conclusion: The results of the present study confirm that BCG has no relevant effect on non-mycobacterial infectious diseases and other immune-mediated diseases in a population of generally mycobacteria-naïve older Dutch individuals in the two years following vaccination. However, our study suggests that BCG may aggravate pre-existing cardiac arrhythmia, which warrants further investigation., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: MGN is a scientific founder of TTxD, Lemba and BioTrip, and a member of the TTxD scientific advisory board. MGN has received research grants from TTxD and GSK., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Introduction: During the COVID19 pandemic, older patients hospitalized for COVID-19 exhibited an increased mortality risk compared to younger patients. While ageing is associated with compromised immune responses and frailty, their contributions and interplay remain understudied. This study investigated the association between inflammatory markers and mortality and potential modification by frailty among older patients hospitalized for COVID-19., Methods: Data were from three multicenter Dutch cohorts (COVID-OLD, CliniCo, Covid-Predict). Patients were 70 years or older, hospitalized for COVID-19and categorized into three frailty groups: fit (Clinical frailty score (CFS) 1-3), pre-frail (CFS 4-5), and frail (CFS 6-9). Immunological markers (lymphocyte count, neutrophil count, C-reactive protein, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and systemic inflammation index (SII)) were measured at baseline. Associations with in hospital mortality were examined using logistic regression., Results: A total of 1697 patients were included from COVID-OLD, 656 from Covid-Predict, and 574 from CliniCo. The median age was 79, 77, and 78 years for each cohort. Hospital mortality rates were 33 %, 27 % and 39 % in the three cohorts, respectively. A lower CRP was associated with a higher frailty score in all three cohorts (all p < 0.01). Lymphocyte count, neutrophil count, NLR, PLR, or SII, were similar across frailty groups. Higher CRP levels were associated with increased in-hospital mortality risk across all frailty groups, across all cohorts (OR (95 % CI), 2.88 (2.20-3.78), 3.15 (1.95-5.16), and 3.28 (1.87-5.92)), and frailty did not modify the association between inflammatory markers and in-hospital mortality (all p-interaction>0.05)., Conclusion: While frailty is a significant factor in determining overall outcomes in older patients, our study suggests that the elevated risk of mortality in older patients with frailty compared to fit patients is likely not explained by difference in inflammatory responses., Competing Interests: Declaration of competing interest The authors declare that they have no known conflict of interest., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Objectives: To evaluate the quality of culture follow-up after emergency department (ED) discharge in patients with urinary tract infections (UTIs)., Methods: This convergent mixed methods study included an observational cohort study and a qualitative interview study in UTI patients discharged from the ED of a Dutch university hospital. The primary outcomes of the observational study were the proportion of patients requiring adjustment of antibiotic therapy after culture review, and the proportion of patients in whom these adjustments were made. Logistic regression identified factors associated with these outcomes. Interviews assessed patient experiences and transcripts were analysed using inductive thematic content analysis. Integration of the results informed recommendations for high-quality follow-up., Results: Out of 455 patients, 285 (63%) required culture-based treatment adjustments. In most patients, no adjustments were made (239/285, 84%). De-escalation was most frequently omitted (98%), followed by discontinuation of antibiotics (92%). A mean of 7.1 (SD  3.8) antibiotic days per patient could have been avoided in 103 patients. Patients with diabetes were less likely to require adjustments (aOR   0.50, 95%-CI  0.29-0.85). Patients with moderate or severe renal impairment (aOR  4.1, 95%-CI  1.45-11.33; aOR  4.2, 95%-CI   1.50-11.94) or recurrent UTIs (aOR  5.0, 95%-CI  2.27-11.18) were more likely to have received necessary adjustments. Twelve interviews also revealed varying degrees of follow-up. Three themes were identified: 'information and communication', 'coordination and accessibility of care' and 'individual needs and preferences'. Recommendations for high-quality follow-up advocate a person centred approach., Conclusions: This study highlights the importance of urine culture follow-up after ED discharge, mainly to reduce unnecessary antibiotic treatment, promote de-escalation and improve patient experience., (© The Author(s) 2024. Published by Oxford University Press on behalf of British Society for Antimicrobial Chemotherapy.)

The mRNA-based BNT162b2 protects against severe disease and mortality caused by SARS-CoV-2 via induction of specific antibody and T-cell responses. Much less is known about its broad effects on immune responses against other pathogens. Here, we investigated the adaptive immune responses induced by BNT162b2 vaccination against various SARS-CoV-2 variants and its effects on the responsiveness of immune cells upon stimulation with heterologous stimuli. BNT162b2 vaccination induced effective humoral and cellular immunity against SARS-CoV-2 that started to wane after six months. We also observed long-term transcriptional changes in immune cells after vaccination. Additionally, vaccination with BNT162b2 modulated innate immune responses as measured by inflammatory cytokine production after stimulation - higher IL-1/IL-6 release and decreased IFN-α production. Altogether, these data expand our knowledge regarding the overall immunological effects of this new class of vaccines and underline the need for additional studies to elucidate their effects on both innate and adaptive immune responses., Competing Interests: Declaration of Competing Interest M.G.N and L.A.B.J are scientific founders of TTxD and Lemba., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Objectives: To test whether Bacillus Calmette-Guérin (BCG) vaccination would reduce the incidence of COVID-19 and other respiratory tract infections (RTIs) in older adults with one or more comorbidities., Methods: Community-dwelling adults aged 60 years or older with one or more underlying comorbidities and no contraindications to BCG vaccination were randomized 1:1 to BCG or placebo vaccination and followed for 6 months. The primary endpoint was a self-reported, test-confirmed COVID-19 incidence. Secondary endpoints included COVID-19 hospital admissions and clinically relevant RTIs (i.e. RTIs including but not limited to COVID-19 requiring medical intervention). COVID-19 and clinically relevant RTI episodes were adjudicated. Incidences were compared using Fine-Gray regression, accounting for competing events., Results: A total of 6112 participants with a median age of 69 years (interquartile range, 65-74) and median of 2 (interquartile range, 1-3) comorbidities were randomized to BCG (n = 3058) or placebo (n = 3054) vaccination. COVID-19 infections were reported by 129 BCG recipients compared to 115 placebo recipients [hazard ratio (HR), 1.12; 95% CI, 0.87-1.44]. COVID-19-related hospitalization occurred in 18 BCG and 21 placebo recipients (HR, 0.86; 95% CI, 0.46-1.61). During the study period, 13 BCG recipients died compared with 18 placebo recipients (HR, 0.71; 95% CI, 0.35-1.43), of which 11 deaths (35%) were COVID-19-related: six in the placebo group and five in the BCG group. Clinically relevant RTI was reported by 66 BCG and 72 placebo recipients (HR, 0.92; 95% CI, 0.66-1.28)., Discussion: BCG vaccination does not protect older adults with comorbidities against COVID-19, COVID-19 hospitalization, or clinically relevant RTIs., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background and Objective: A recent study has suggested that circadian rhythm has an important impact on the immunological effects induced by Bacillus Calmette-Guérin (BCG) vaccination. The objective of this study was to evaluate whether the timing of BCG vaccination (morning or afternoon) affects its impact on severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infections and clinically relevant respiratory tract infections (RTIs)., Methods: This is a post-hoc analysis of the BCG-CORONA-ELDERLY (NCT04417335) multicenter, placebo-controlled trial, in which participants aged 60 years and older were randomly assigned to vaccination with BCG or placebo, and followed for 12 months. The primary endpoint was the cumulative incidence of SARS-CoV-2 infection. To assess the impact of circadian rhythm on the BCG effects, participants were divided into four groups: vaccinated with either BCG or placebo in the morning (between 9:00h and 11:30h) or in the afternoon (between 14:30h and 18:00h)., Results: The subdistribution hazard ratio of SARS-CoV-2 infection in the first six months after vaccination was 2.394 (95% confidence interval [CI], 0.856-6.696) for the morning BCG group and 0.284 (95% CI, 0.055-1.480) for the afternoon BCG group. When comparing those two groups, the interaction hazard ratio was 8.966 (95% CI, 1.366-58.836). In the period from six months until 12 months after vaccination cumulative incidences of SARS-CoV-2 infection were comparable, as well as cumulative incidences of clinically relevant RTI in both periods., Conclusion: Vaccination with BCG in the afternoon offered better protection against SARS-CoV-2 infections than BCG vaccination in the morning in the first six months after vaccination., Competing Interests: MN is scientific founder of TTxD and Lemba has received scientific support from GSK, Ono Pharma, and TTxD. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Föhse, Taks, Moorlag, Bonten, van Crevel, ten Oever, van Werkhoven, Netea, van de Maat and Hoogerwerf.)

Background: The Dutch Working Party on Antibiotic Policy (SWAB) in collaboration with relevant professional societies, has updated their evidence-based guidelines on empiric antibacterial therapy of sepsis in adults., Methods: Our multidisciplinary guideline committee generated ten population, intervention, comparison, and outcome (PICO) questions relevant for adult patients with sepsis. For each question, a literature search was performed to obtain the best available evidence and assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system. The quality of evidence for clinically relevant outcomes was graded from high to very low. In structured consensus meetings, the committee formulated recommendations as strong or weak. When evidence could not be obtained, recommendations were provided based on expert opinion and experience (good practice statements)., Results: Fifty-five recommendations on the antibacterial therapy of sepsis were generated. Recommendations on empiric antibacterial therapy choices were differentiated for sepsis according to the source of infection, the potential causative pathogen and its resistance pattern. One important revision was the distinction between low, increased and high risk of infection with Enterobacterales resistant to third generation cephalosporins (3GRC-E) to guide the choice of empirical therapy. Other new topics included empirical antibacterial therapy in patients with a reported penicillin allergy and the role of pharmacokinetics and pharmacodynamics to guide dosing in sepsis. We also established recommendations on timing and duration of antibacterial treatment., Conclusions: Our multidisciplinary committee formulated evidence-based recommendations for the empiric antibacterial therapy of adults with sepsis in The Netherlands., (© 2022. The Author(s).)

Background: Recognising patients who need immediate hospital treatment for sepsis while simultaneously limiting unnecessary referrals is challenging for GPs., Aim: To develop and validate a sepsis prediction model for adult patients in primary care., Design and Setting: This was a prospective cohort study in four out-of-hours primary care services in the Netherlands, conducted between June 2018 and March 2020., Method: Adult patients who were acutely ill and received home visits were included. A total of nine clinical variables were selected as candidate predictors, next to the biomarkers C-reactive protein, procalcitonin, and lactate. The primary endpoint was sepsis within 72 hours of inclusion, as established by an expert panel. Multivariable logistic regression with backwards selection was used to design an optimal model with continuous clinical variables. The added value of the biomarkers was evaluated. Subsequently, a simple model using single cut-off points of continuous variables was developed and externally validated in two emergency department populations., Results: A total of 357 patients were included with a median age of 80 years (interquartile range 71-86), of which 151 (42%) were diagnosed with sepsis. A model based on a simple count of one point for each of six variables (aged >65 years; temperature >38°C; systolic blood pressure ≤110 mmHg; heart rate >110/min; saturation ≤95%; and altered mental status) had good discrimination and calibration (C-statistic of 0.80 [95% confidence interval = 0.75 to 0.84]; Brier score 0.175). Biomarkers did not improve the performance of the model and were therefore not included. The model was robust during external validation., Conclusion: Based on this study's GP out-of-hours population, a simple model can accurately predict sepsis in acutely ill adult patients using readily available clinical parameters., (© The Authors.)

Background: Knowledge on bacterial co-infections in COVID-19 is crucial to use antibiotics appropriately. Therefore, we aimed to determine the incidence of bacterial co-infections, antibiotic use and application of antimicrobial stewardship principles in hospitalized patients with COVID-19., Methods: We performed a retrospective observational study in four hospitals (1 university, 2 non-university teaching, 1 non-teaching hospital) in the Netherlands from March to May 2020 including consecutive patients with PCR-confirmed COVID-19. Data on first microbiological investigations obtained at the discretion of the physician and antibiotic use in the first week of hospital admission were collected., Results: Twelve (1.2%) of the 925 patients included had a documented bacterial co-infection (75.0% pneumonia) within the first week. Microbiological testing was performed in 749 (81%) patients: sputum cultures in 105 (11.4%), blood cultures in 711 (76.9%), pneumococcal urinary antigen testing in 202 (21.8%), and Legionella urinary antigen testing in 199 (21.5%) patients, with clear variation between hospitals. On presentation 556 (60.1%; range 33.3-73.4%) patients received antibiotics for a median duration of 2 days (IQR 1-4). Intravenous to oral switch was performed in 41 of 413 (9.9%) patients who received intravenous treatment >48 h. Mean adherence to the local guideline on empiric antibiotic therapy on day 1 was on average 60.3% (range 45.3%-74.7%)., Conclusions: On presentation to the hospital bacterial co-infections are rare, while empiric antibiotic use is abundant. This implies that in patients with COVID-19 empiric antibiotic should be withheld. This has the potential to dramatically reduce the current overuse of antibiotics in the COVID-19 pandemic.

Importance: Although inadequate sleep has a proven negative association with health care outcomes, to date, no large-scale studies have examined sleep in general hospital wards., Objectives: To assess the subjective quantity and quality of sleep and to identify the hospital-related factors associated with sleep disturbances in hospitalized patients., Design: For this nationwide, single-day, multicenter, cross-sectional, observational study, which took place on February 22, 2017, all hospitals in the Netherlands were encouraged by word of mouth and conventional and social media to participate in this study. A total of 39 hospitals participated. Included patients were at least 18 years of age, were able to give informed consent, and had spent at least 1 night in a regular-care hospital ward., Exposures: Hospitalization in a regular-care ward., Main Outcomes and Measures: Quantity and quality of last night's sleep in the hospital compared with habitual sleep at home the month before hospitalization. The Consensus Sleep Diary and the Dutch-Flemish Patient-Reported Outcomes Measurement Information System (PROMIS) Sleep Disturbance item bank were used. Complementary questions assessed sleep-disturbing factors., Results: A total of 2005 patients were included (median age, 68 years; interquartile range, 57-77 years; 994 of 1935 [51.4%] were male [70 patients did not identify their sex]). Compared with habitual sleep at home, the total sleep time in the hospital was 83 minutes (95% CI, 75-92 minutes; P < .001) shorter. The mean number of nocturnal awakenings was 2.0 (95% CI, 1.9-2.1) times at home vs 3.3 (95% CI, 3.2-3.5) times during hospitalization (P < .001). Patients woke up 44 minutes (95% CI, 44-45 minutes; P < .001) earlier than their habitual wake-up time at home. A total of 1344 patients (70.4%) reported having been awakened by external causes, which in 718 (35.8%) concerned hospital staff. All aspects of sleep quality measured using PROMIS questions were rated worse during hospitalization than at home. The most reported sleep-disturbing factors were noise of other patients, medical devices, pain, and toilet visits., Conclusions and Relevance: This study demonstrated that the duration and quality of sleep in hospitalized patients were significantly affected and revealed many potentially modifiable hospital-related factors negatively associated with sleep. Raising awareness about the importance of adequate sleep in the vulnerable hospital population and introducing interventions to target sleep-disturbing factors may improve healing.

Background: Streptococcus pneumoniae is the most commonly identified pathogen in community-acquired pneumonia (CAP). Myeloid-related protein (MRP) 8/14 is a major component of neutrophils that is released upon infection or injury. MRP8/14 is essential for protective immunity during infection by a variety of micro-organisms through its capacity to chelate manganese and zinc. Here, we aimed to determine the role of MRP8/14 in pneumococcal pneumonia., Methods: MRP8/14 was determined in bronchoalveolar lavage fluid (BALF) and serum of CAP patients, in lung tissue of patients who had succumbed to pneumococcal pneumonia, and in BALF of healthy subjects challenged with lipoteichoic acid (a component of the gram-positive bacterial cell wall) via the airways. Pneumonia was induced in MRP14 deficient and normal wildtype mice. The effect of MRP8/14 on S. pneumoniae growth was studied in vitro., Results: CAP patients displayed high MRP8/14 levels in BALF, lung tissue and serum. Healthy subjects challenged with lipoteichoic acid demonstrated elevated MRP8/14 in BALF. Likewise, mice with pneumococcal pneumonia had high MRP8/14 levels in lungs and the circulation. MRP14 deficiency, however, was associated with reduced bacterial growth and lethality, in the absence of notable effects on the inflammatory response. High zinc levels strongly inhibited growth of S. pneumoniae in vitro, which was partially reversed by MRP8/14., Conclusions: In sharp contrast to its previously reported host-protective role in several infections, the present results reveal that in a model of CAP, MRP8/14 is misused by S. pneumoniae, facilitating bacterial growth by attenuating zinc toxicity toward the pathogen., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)

Lipopolysaccharide (LPS) is ubiquitous in the environment. Inhalation of LPS has been implicated in the pathogenesis and/or severity of several lung diseases, including pneumonia, chronic obstructive pulmonary disease and asthma. Alveolar macrophages are the main resident leukocytes exposed to inhaled antigens. To obtain insight into which innate immune pathways become activated within human alveolar macrophages upon exposure to LPS in vivo, we conducted a study in eight healthy humans, in which we instilled sterile saline into a lung segment by bronchoscope, followed by instillation of LPS into the contralateral lung. Six hours later, a bilateral bronchoalveolar lavage was performed and whole-genome transcriptional profiling was done on purified alveolar macrophages, comparing cells exposed to saline or LPS from the same individuals. LPS induced differential expression of 2,932 genes in alveolar macrophages; 1,520 genes were upregulated, whereas 1,440 genes were downregulated. A total of 26 biological functions were overrepresented in LPS-exposed macrophages; 44 canonical pathways affected by LPS were identified, among which the genes associated with the role of pattern recognition receptors in recognition of bacteria and viruses represented the top pathway. Other pathways included cellular immune response, signaling by tumor necrosis factor (receptor) family members, cytokine signaling and glucocorticoid receptor signaling. These results reveal for the first time a large number of functional pathways influenced by the biologically relevant challenge provided by LPS administered into the airways. These data can assist in identifying novel targets for therapeutic intervention in pulmonary diseases associated with LPS exposure, including pneumonia, asthma and chronic obstructive pulmonary disease.

Pneumonia is a common cause of morbidity and mortality and the most frequent source of sepsis. Bacteria that try to invade normally sterile body sites are recognized by innate immune cells through pattern recognition receptors, among which toll-like receptors (TLRs) feature prominently. Interleukin-1 receptor (IL-1R)-associated kinase (IRAK)-M is a proximal inhibitor of TLR signaling expressed by epithelial cells and macrophages in the lung. To determine the role of IRAK-M in host defense against bacterial pneumonia, IRAK-M-deficient (IRAK-M(-/-)) and normal wild-type (WT) mice were infected intranasally with Klebsiella pneumoniae. IRAK-M mRNA was upregulated in lungs of WT mice with Klebsiella pneumonia, and the absence of IRAK-M resulted in a strongly improved host defense as reflected by reduced bacterial growth in the lungs, diminished dissemination to distant body sites, less peripheral tissue injury and better survival rates. Although IRAK-M(-/-) alveolar macrophages displayed enhanced responsiveness toward intact K. pneumoniae and Klebsiella lipopolysaccharide (LPS) in vitro, IRAK-M(-/-) mice did not show increased cytokine or chemokine levels in their lungs after infection in vivo. The extent of lung inflammation was increased in IRAK-M(-/-) mice shortly after K. pneumoniae infection, as determined by semiquantitative scoring of specific components of the inflammatory response in lung tissue slides. These data indicate that IRAK-M impairs host defense during pneumonia caused by a common gram-negative respiratory pathogen.

Rationale: After surviving the initial hyperinflammatory phase, patients with sepsis display features consistent with immunosuppression, which renders the host susceptible to nosocomial infections, in particular bacterial pneumonia. Suppression of tumorigenicity 2 (ST2) is a negative regulator of Toll-like receptor signaling implicated in endotoxin tolerance., Objectives: The present study sought to determine the role of ST2 in modulating host defense in the lung during sepsis, using a murine model of cecal ligation and puncture (CLP)-induced sepsis followed by a secondary infection with Pseudomonas aeruginosa via the airways., Methods: CLP or sham surgery was performed on BALB/c wild-type (WT) and ST2 knockout (KO) mice, and 24 hours later animals were challenged with 10(8) live P. aeruginosa., Measurements and Main Results: CLP mice demonstrated impaired clearance of Pseudomonas from their lungs and reduced pulmonary levels of tumor necrosis factor-α and IL-6 compared with sham mice. After CLP, ST2KO mice with secondary pneumonia displayed a strongly improved survival and a better bacterial clearance compared with WT mice, which was accompanied by enhanced lung inflammation. CLP did not influence the responsiveness of alveolar macrophages toward P. aeruginosa ex vivo irrespective of the st2 genotype. In contrast, CLP resulted in a reduced capacity of WT CD4(+) and CD8(+) T cells to produce IFN-γ and tumor necrosis factor-α, an immune suppressive effect that was not seen in ST2KO mice., Conclusions: These findings indicate that gene products of ST2 contribute to the immune-compromised state during sepsis and the ensuing disturbed homeostasis of lung host defense.

Klebsiella pneumoniae is a common cause of nosocomial pneumonia. Osteopontin (OPN) is a phosphorylated glycoprotein involved in inflammatory processes, some of which is mediated by CD44. The aim of this study was to determine the role of OPN during K. pneumoniae-induced pneumonia. Wild-type (WT) and OPN knockout (KO) mice were intranasally infected with 10⁴ colony forming units of K. pneumoniae, or administered Klebsiella lipopolysaccharides (LPS). In addition, recombinant OPN (rOPN) was intranasally administered to WT and CD44 KO mice. During Klebsiella pneumonia, WT mice displayed elevated pulmonary and plasma OPN levels. OPN KO and WT mice showed similar pulmonary bacterial loads 6 h after infection; thereafter, Klebsiella loads were higher in lungs of OPN KO mice and the mortality rate in this group was higher than in WT mice. Early neutrophil recruitment into the bronchoalveolar space was impaired in the absence of OPN after intrapulmonary delivery of either Klebsiella bacteria or Klebsiella LPS. Moreover, rOPN induced neutrophil migration into the bronchoalveolar space, independent from CD44. In vitro, OPN did not affect K. pneumoniae growth or neutrophil function. In conclusion, OPN levels were rapidly increased in the bronchoalveolar space during K. pneumoniae pneumonia, where OPN serves a chemotactic function towards neutrophils, thereby facilitating an effective innate immune response.

Purpose: Patients with sepsis-after surviving the initial hyperinflammatory phase-display features consistent with immunosuppression, including hyporesponsiveness of immunocompetent cells to bacterial agents. Immunosuppression is thought to be facilitated by negative regulators of toll-like receptors, including membrane-bound ST2. We investigated the release of soluble ST2 (sST2), a decoy receptor that inhibits membrane-bound ST2 signaling, during sepsis., Methods: The study population comprised 95 patients with severe sepsis admitted to one of two intensive care units (ICUs) at the day the diagnosis of severe sepsis was made. Blood was obtained daily from admission (day 0) until day 7 and finally at day 14. Twenty-four healthy subjects served as controls. sST2 and cytokines were measured in serum., Results: Mortality among patients was 34% in the ICU and 45% in the hospital. On admission, sepsis patients had higher sST2 levels [10,989 (7,871-15,342) pg/ml, geometric mean (95% confidence interval, CI)] than controls [55 (20-145) pg/ml, P < 0.0001]. Serum sST2 remained elevated in patients from day 0 to 14 and correlated with disease severity scores (P < 0.001) and cytokine levels on day 0 and during course of disease (P < 0.0001). Nonsurvivors displayed elevated sST2 levels compared with survivors of the intensive care unit (P < 0.0001)., Conclusions: Sepsis results in sustained elevation of serum sST2 levels, which correlates with disease severity and mortality.

The airways are continuously exposed to respiratory pathogens, which may result in bacterial pneumonia, one of the most common infectious diseases and the leading cause of sepsis. Considering that recurrent exposure to microbial products can lead to tolerance of immune cells, and that this might contribute to the susceptibility to nosocomial infection, we investigated the effect of in vivo lipopolysaccharide (LPS) instillation on the responsiveness of alveolar macrophages. In eight healthy humans, sterile saline was instilled into a lung segment by bronchoscope, followed by instillation of LPS into the contralateral lung; 6 hours later, a bilateral bronchoalveolar lavage was performed, and purified alveolar macrophages were ex vivo stimulated with LPS or lipoteichoic acid (LTA), triggering Toll-like receptor (TLR)-4 and -2, respectively. In vivo LPS-exposed alveolar macrophages were primed, as reflected by increased ex vivo LPS- and LTA-induced IL-1 beta and IL-6 gene expression and production compared with in vivo saline-exposed alveolar macrophages. LPS instillation did not influence the surface expression of TLR4 or TLR2. Furthermore, LPS instillation did not impact on the expression of a number of extracellular and intracellular regulators of TLR signaling. However, p38 mitogen-activated protein kinase remained phosphorylated in alveolar macrophages upon LPS instillation. The current data demonstrate that LPS instillation in the human lung primes alveolar macrophages for further stimulation with either LPS or LTA, possibly by sustained p38 mitogen-activated protein kinase activation.

Introduction: Sepsis is associated with a dysregulation of apoptosis in immune cells, which has been implicated in both immunosuppression and multiple organ failure. We describe the expression profiles of genes encoding key regulators of apoptosis in highly purified monocytes, granulocytes and CD4+ T lymphocytes., Methods: Sixteen patients with sepsis were recruited from the intensive care unit and were compared with 24 healthy controls. RNA was isolated from highly purified monocyte, granulocyte and CD4+ T-lymphocyte populations. Gene expression profiles were determined using multiplex ligation-dependent probe amplification for the simultaneous detection of 30 pro- and anti-apoptotic target genes., Results: Relative to healthy controls, patients with sepsis showed increased transcription of both pro- and anti-apoptotic genes in peripheral blood leukocytes. Specific monocyte, granulocyte and CD4+ T-lymphocyte mRNA profiles were identified. Anti-apoptotic profiles were found in monocytes and granulocytes, while CD4+ T lymphocytes displayed a foremost pro-apoptotic mRNA profile., Conclusions: These data indicate that in patients with sepsis, the alterations in apoptosis of circulating leukocytes occur in a cell-specific manner., (2010 S. Karger AG, Basel.)

Rationale: Recognition of pathogen-associated molecular patterns by Toll-like receptors (TLRs) is considered to be important for an appropriate immune response against pathogens that enter the lower airways., Objectives: We studied the effects of two different TLR agonists relevant for respiratory infections in the human lung: lipoteichoic acid (LTA; TLR2 agonist, component of gram-positive bacteria) and lipopolysaccharide (LPS; TLR4-agonist, component of gram-negative bacteria)., Methods: Fifteen healthy subjects were given LPS or LTA: by bronchoscope, sterile saline was instilled into a lung segment followed by instillation of LTA or LPS into the contralateral lung. After 6 hours, a bronchoalveolar lavage was performed and inflammatory parameters were determined. Isolated RNA from purified alveolar macrophages was analyzed by multiplex ligation-dependent probe amplification. In addition, spontaneous cytokine release by alveolar macrophages was measured., Measurements and Main Results: Marked differences were detected between LTA- and LPS-induced lung inflammation. Whereas both elicited neutrophil recruitment, only LPS instillation was associated with activation of neutrophils (CD11b surface expression, degranulation product levels) and consistent rises of chemo-/cytokine levels. Moreover, LPS but not LTA activated alveolar macrophages, as reflected by enhanced expression of 10 different mRNAs encoding proinflammatory mediators and increased spontaneous cytokine release upon incubation ex vivo. Remarkably, only LTA induced C5a release., Conclusions: This is the first study to report the in vivo effects of LTA in men and to compare inflammation induced by LTA and LPS in the human lung. Our data suggest that stimulation of TLR2 or TLR4 results in differential pulmonary inflammation, which may be of relevance for understanding pathogenic mechanisms at play during gram-positive and gram-negative respiratory tract infection.

Objectives: To record the number of haemophilicas aged 0-18 years in the Western Cape (WC), what event led to the diagnosis, the level of clotting factor, treatment, functional status of their joints and impact of the disease on the family., Design: A prospective study of patients registered with the South African National Haemophilia Registry and new patients, utilising the patients' paediatricians, hospital records, patient and guardian interviews, physical examination and provincial nurse haemophilia co-ordinators., Setting: Haemophilia care centres at the three WC academic hospitals, regional hospitals and homes of patients. Two elective medical students, MHH and JJH, collected the information., Subjects: All boys with confirmed haemophilia A or B in the WC., Outcome Measures: Events that led to diagnosis, degree of haemophilia, use of clotting factor, functional status, and effect on family., Results: Of 78 patients (59 haemophilia A, 19 haemophilia B) identified, 49 could be studied. Forty-three per cent had severe, 29% moderate and 22% mild disease (6% unknown). Family history was present in 49%, but led to diagnosis in only 12%. The most common first symptoms were subcutaneous and mucosal bleeding. Delay in diagnosis varied from 0 to 9 months. Twenty-nine per cent of guardians were suspected of child abuse. RSA produced clotting factor was used 'on demand' in 73% of patients, for periodic prophylaxis in 20% and as continuous prophylaxis in 7%. Joints were functionally restricted in 43% of patients. The majority of guardians (59%) said the disease had a major impact on the family., Conclusions: The diagnosis of haemophilia in children with a positive family history was often delayed. Haemophilia causes significant morbidity in our patients and their families.