Hybrid Delivery of Mindfulness Meditation and Perceived Stress in Pediatric Resident Physicians: A Randomized Clinical Trial of In-Person and Digital Mindfulness Meditation

Physicians are experiencing epidemic levels of work-related stress and burnout. Determine efficacy of mindfulness meditation delivered as a hybrid (in-person and digital) format to reduce perceived stress in pediatric residents. Pediatric residents (n = 66) were block randomized to a hybrid Mindful Awareness Practices (MAPs) intervention, comprised of one in-person 60-min session and 6-week access to a digitally delivered MAPs curriculum (n = 27) or wait-list control (n = 39). Perceived Stress Scale (PSS) was administered at baseline and post-intervention as the primary outcome measure. A priori secondary outcomes were measured using the Abbreviated Maslach Burnout Inventory-9, Beck Depression Inventory, Beck Anxiety Inventory, UCLA Loneliness Scale, and Pittsburgh Sleep Quality Index. After the first session, 58% participated at least one digital session (M = 2.0; SD = 1.3). MAPs participants showed significant decrease in PSS compared to controls, with between-group mean difference of 2.20 (95% CI 0.47-3.93) at post-intervention (effect size 0.91; 0.19-1.62). No secondary outcome group differences were detected. Exposure to a hybrid mindfulness intervention was associated with improvement in perceived stress among pediatric residents.Trial Registration: NCT03613441.

Advances in medical management of acute liver failure in children: promoting native liver survival

Paediatric acute liver failure (PALF) is defined as a biochemical evidence of acute liver injury in a child with no previous history of chronic liver disease characterised by an international normalised ratio (INR) of 1·5 or more unresponsive to vitamin K with encephalopathy, or INR of 2·0 or more with or without encephalopathy. PALF can rapidly progress to multiorgan dysfunction or failure. Although the transplant era has substantially changed the outlook for these patients, transplantation itself is not without risks, including those associated with life-long immunosuppression. Consequently, there has been an increased focus on improving medical management to prioritise bridging of patients to native liver survival, which is possible due to improved understanding of the underlying pathophysiology of multiorgan involvement in PALF. In this Review, we discuss recent advances in the medical management of PALF with an aim of reducing the need for liver transplantation. The Review will focus on the non-specific immune-mediated inflammatory response, extracorporeal support devices, neuromonitoring and neuroprotection, and emerging cellular and novel future therapeutic options.

Vaccine apartheid: This is not the way to end the pandemic

There are many reasons why the international community as a whole should advocate for COVID-19 vaccine equity: global economic recession, uncontrolled outbreaks with higher risk of virus variants and persistent unsafe travelling in an era of now vaccine-preventable cause of death. This inequity is an avoidable threat to global health. Funding agencies, policy makers, drug companies and NGOs among others have the moral duty to end this vaccine apartheid and to make vaccine equity a reality. In this viewpoint, we discuss how inequalities in vaccination access affect a proper control of the pandemic, highlighting specific consequences on child health.

Structured Chart Review: Assessment of a Structured Chart Review Methodology

BACKGROUND AND OBJECTIVES

Chart reviews are frequently used for research, care assessments, and quality improvement activities despite an absence of data on reliability and validity. We aim to describe a structured chart review methodology and to establish its validity and reliability.

METHODS

A generalizable structured chart review methodology was designed to evaluate causes of morbidity or mortality and to identify potential therapeutic advances. The review process consisted of a 2-tiered approach with a primary review completed by a site physician and a short secondary review completed by a central physician. A total of 327 randomly selected cases of known mortality or new morbidities were reviewed. Validity was assessed by using postreview surveys with a Likert scale. Reliability was assessed by percent agreement and interrater reliability.

RESULTS

The primary reviewers agreed or strongly agreed in 94.9% of reviews that the information to form a conclusion about pathophysiological processes and therapeutic advances could be adequately found. They agreed or strongly agreed in 93.2% of the reviews that conclusions were easy to make, and confidence in the process was 94.2%. Secondary reviewers made modifications to 36.6% of cases. Duplicate reviews (n = 41) revealed excellent percent agreement for the causes (80.5%-100%) and therapeutic advances (68.3%-100%). κ statistics were strong for the pathophysiological categories but weaker for the therapeutic categories.

CONCLUSIONS

A structured chart review by knowledgeable primary reviewers, followed by a brief secondary review, can be valid and reliable.

Case Report: Insulin-Dependent Diabetes Mellitus and Diabetic Keto-Acidosis in a Child With COVID-19

During the COVID pandemic, a surge in pediatric Type 1 Diabetes Mellitus (T1DM) cases appears to be occurring, potentially due to the presence of autoantibody-induced immune dysregulation triggered by COVID-19. We describe one such case in a previously healthy 7-year-old with asymptomatic COVID-19 presenting with a high nasopharyngeal SARS CoV-2 virus load, detectable COVID-19 IgG antibodies, diabetic keto-acidosis and islet cell autoantibodies. COVID-19 is not a trivial disease in children and adolescents and can lead to lifelong sequelae such as T1DM. Raising awareness about a possible association between COVID-19 and T1DM in children is critical.

Pathological spontaneous activity as a prognostic marker in chronic inflammatory demyelinating polyneuropathy

BACKGROUND AND PURPOSE

Monitoring of the disease course of patients with chronic inflammatory demyelinating polyneuropathy (CIDP) remains challenging because nerve conduction studies do not adequately correlate with functional disability. The prognostic value of pathological spontaneous activity (PSA) in needle electromyography (EMG) in different CIDP subgroups in a longitudinal context has, to date, not been analysed. We aimed to determine whether PSA was a prognostic marker or a marker of disease activity in a cohort of patients with CIDP.

METHODS

A total of 127 patients with CIDP spectrum disorder were retrospectively analysed over 57 ± 47 months regarding the occurrence of PSA (fibrillations and positive sharp waves). The presence of PSA at diagnosis, newly occurring PSA, and continuously present PSA were longitudinally correlated with clinical disability using the Inflammatory Neuropathy Cause and Treatment Overall Disability Sum Score (INCAT-ODSS) and CIDP subtype.

RESULTS

Pathological spontaneous activity occurred in 49.6% of all CIDP patients at first diagnosis. More frequent evidence of PSA was significantly associated with a higher INCAT-ODSS at the last follow-up. Continuous and new occurrence of PSA were associated with higher degree of disability at the last follow-up. The majority of patients with sustained evidence of PSA were characterized by an atypical phenotype, higher degree of disability, and the need for escalation of treatment.

CONCLUSIONS

Pathological spontaneous activity was associated with a higher degree of disability and occurred more frequently in atypical CIDP variants according to the longitudinal data of a large cohort of patients with CIDP. Our results showed that EMG examination was an adequate marker for disease progression and should be evaluated during the disease course.

Hemostatic Balance in Pediatric Acute Liver Failure: Epidemiology of Bleeding and Thrombosis, Physiology, and Current Strategies

Pediatric Acute Liver Failure (PALF) is a rapidly progressive clinical syndrome encountered in the pediatric ICU which may rapidly progress to multi-organ dysfunction, and on occasion to life threatening cerebral edema and hemorrhage. Pediatric Acute Liver Failure is defined as severe acute hepatic dysfunction accompanied by encephalopathy and liver-based coagulopathy defined as prolongation of International Normalized Ratio (INR) >1.5. However, coagulopathy in PALF is complex and warrants a deeper understanding of the hemostatic balance in acute liver failure. Although an INR value of >1.5 is accepted as the evidence of coagulopathy and has historically been viewed as a prognostic factor of PALF, it may not accurately reflect the bleeding risk in PALF since it only measures procoagulant factors. Paradoxically, despite the prolongation of INR, bleeding risk is lower than expected (around 5%). This is due to "rebalanced hemostasis" due to concurrent changes in procoagulant, anticoagulant and fibrinolytic systems. Since the liver is involved in both procoagulant (Factors II, V, IX, XI, and fibrinogen) and anticoagulant (Protein C, Protein S, and antithrombin) protein synthesis, PALF results in "rebalanced hemostasis" or even may shift toward a hypercoagulable state. In addition to rebalanced coagulation there is altered platelet production due to decreased thrombopoietin production by liver, increased von Willebrand factor from low grade endothelial cell activation, and hyperfibrinolysis and dysfibrinogenemia from altered synthetic liver dysfunction. All these alterations contribute to the multifactorial nature of coagulopathy in PALF. Over exuberant use of prophylactic blood products in patients with PALF may contribute to morbidities such as fluid overload, transfusion-associated lung injury, and increased thrombosis risk. It is essential to use caution when using INR values for plasma and factor administration. In this review we will summarize the complexity of coagulation in PALF, explore "rebalanced hemostasis," and discuss the limitations of current coagulation tests. We will also review strategies to accurately diagnose the coagulopathy of PALF and targeted therapies.

Feasibility of Online Mental Wellness Self-assessment and Feedback for Pediatric and Neonatal Critical Care Nurses

PURPOSE

The primary goal of this study was to test the feasibility of an educational online self-assessment of burnout, resilience, trauma, depression, anxiety, and common workplace stressors among nurses working in a pediatric intensive care unit or neonatal intensive care unit setting. The secondary, exploratory objectives were to estimate the prevalence of psychiatric symptoms in this sample and to identify those variables that most strongly predict burnout.

DESIGN AND METHODS

Data from optional and anonymous online measures were analyzed for 115 nurses (67.9% aged 25-44; 61.7% Caucasian) working in an urban children's hospital pediatric or neonatal ICU. Multiple linear regressions identified demographic variables and workplace stressors that significantly predicted each of three components of burnout.

RESULTS

Most respondents found the educational assessment and feedback to be helpful. Choosing nursing as a second career was associated with better resilience. Having worked in ICU settings longer and being older were both linked to lower levels of anxiety. Predictors of burnout varied across the three burnout subscales.

CONCLUSIONS

Implementation of an online self-assessment with immediate educational feedback is feasible in critical care settings. The variability of predictors across the three burnout subscales indicates the need for tailored interventions for those at risk. Future research may include follow-up of nurses to examine changes in scores over time and expansion of the tool for other medical personnel.

PRACTICE IMPLICATIONS

An educational online self-assessment can be a helpful tool for pediatric critical care nurses experiencing varying degrees of burnout and distress.

Percutaneous Removal of a Cardiac Mass in a Patient with Infective Endocarditis: A Case Report

Infective endocarditis (IE) in the pediatric population is uncommon and presents with nonspecific signs. Nonetheless, prompt diagnosis and management are critical given its high mortality rate. We present the case of a 15-year-old boy who initially presented with bilateral multifocal pneumonia and was found to have IE with a right ventricular vegetation. The vegetation was removed percutaneously, obviating a more invasive surgical approach. The patient tolerated the procedure well and rapidly improved following removal of the vegetation. This case report highlights the utility of a novel, minimally invasive approach for the management of cardiac masses.

Pathophysiology and Management of Acute Respiratory Distress Syndrome in Children

Acute respiratory distress syndrome (ARDS) is a syndrome of noncardiogenic pulmonary edema and hypoxia that accompanies up to 30% of deaths in pediatric intensive care units. Pediatric ARDS (PARDS) is diagnosed by the presence of hypoxia, defined by oxygenation index or Pao₂/Fio₂ ratio cutoffs, and new chest infiltrate occurring within 7 days of a known insult. Hallmarks of ARDS include hypoxemia and decreased lung compliance, increased work of breathing, and impaired gas exchange. Mortality is often accompanied by multiple organ failure. Although many modalities to treat PARDS have been investigated, supportive therapies and lung protective ventilator support remain the mainstay.

Endogenous hepcidin and its agonist mediate resistance to selected infections by clearing non-transferrin-bound iron

The iron-regulatory hormone hepcidin is induced early in infection, causing iron sequestration in macrophages and decreased plasma iron; this is proposed to limit the replication of extracellular microbes, but could also promote infection with macrophage-tropic pathogens. The mechanisms by which hepcidin and hypoferremia modulate host defense, and the spectrum of microbes affected, are poorly understood. Using mouse models, we show that hepcidin was selectively protective against siderophilic extracellular pathogens (Yersinia enterocolitica O9) by controlling non-transferrin-bound iron (NTBI) rather than iron-transferrin concentration. NTBI promoted the rapid growth of siderophilic but not nonsiderophilic bacteria in mice with either genetic or iatrogenic iron overload and in human plasma. Hepcidin or iron loading did not affect other key components of innate immunity, did not indiscriminately promote intracellular infections (Mycobacterium tuberculosis), and had no effect on extracellular nonsiderophilic Y enterocolitica O8 or Staphylococcus aureus Hepcidin analogs may be useful for treatment of siderophilic infections.

COPD phenotypes in a lung cancer screening population

BACKGROUND AND AIMS

COPD (chronic obstructive pulmonary disease) is a very heterogeneous disease, and phenotypic categorization of a high-risk population has many potential benefits. The present study uses a symptom questionnaire, low-dose computed tomography (LDCT) and pulmonary function tests (PFT) to phenotypically subgroup a high-risk population.

METHODS

Study group consisted of current or former smokers who underwent lung cancer screening with LDCT as a subgroup of Pittsburgh Lung Screening Study. In addition to LDCT, PFT and a symptom query questionnaire were obtained from each patient.

RESULTS

The study group consisted of 3183 subjects (age 50-79) subdivided into eight groups according to presence of symptoms, obstruction on PFT and presence of emphysema on LDCT. A total of 501 (15.7%) subjects were asymptomatic, with no airflow obstruction or evidence of emphysema. There were 866 (27.2%) subjects with both obstruction on PFT and emphysema on LDCT, but only 660 (20.7%) had symptoms. Five hundred thirty (16.6%) of the subjects had no emphysema on LDCT but had obstruction on PFT, although only 370 (11.6%) had symptoms. Four hundred seventy-four (14.9%) of subjects had emphysema on LDCT, but no airflow obstruction, with 312 (9.8%) symptomatic. Finally, 812 (25.5%) of subjects had no evidence of airflow obstruction on PFT or emphysema on LDCT, but had symptoms.

CONCLUSION

Combining LDCT with PFT and a comprehensive questionnaire allows subgroup classification of COPD phenotypes in a high-risk population and may lead to earlier intervention and an improved framework for future studies.

Prevalence of hepatitis delta virus (HDV) infection in chronic hepatitis B patients in eastern Turkey: still a serious problem to consider

Hepatitis delta virus (HDV) is a serious cause of liver-related morbidity and mortality. Coexistent infection with HDV tends to aggravate the course of hepatitis B virus (HBV)-associated liver disease. The aim of this study was to determine the prevalence of HDV infection among patients chronically infected with HBV in the Elazig region, which is in eastern Turkey. A group of 282 patients infected with chronic HBV were investigated for the study. Anti-HDV seropositivity was evaluated in all patients. The anti-HDV-positive patients were further tested for HDV RNA. Severity of liver disease was assessed by liver biopsy. Regression analysis was used to determine the relationship between independent variables and HDV positivity. Of 282 chronic HBV patients, 192 were men (68.1%) and 90 were women (31.9%). The mean age was 43.8 ± 12.7 (between 18 and 73 years). Anti-HDV was positive in 45.5% of the patients (128/282). Among the 128 anti-HDV-positive patients, 116 were checked for HDV RNA and 56.9% were found positive (66/116). Chronic HDV infection rate was therefore present in at least 23.4% of the whole study group (66/282). There were 83 patients with cirrhosis (29.4%) in the study group. Anti-HDV seroprevalence and HDV RNA presence were higher in those with cirrhosis (61.4% and 42.2%, respectively). No significant relationship was found between anti-HDV seropositivity and demographic factors such as age, sex and operation or transfusion history except family history. HDV-RNA-positive patients had significantly higher ALT and lower albumin levels when compared to HDV-RNA-negative patients. HDV-RNA-positive patients also had a significantly higher fibrosis stage. In conclusion, these findings demonstrated that HDV infection is endemic and still a serious problem in the Elazig region of eastern Turkey. HDV infection is significantly related to the family exposure and increases the risk of severe liver fibrosis in this region.

Identification of a novel human MD-2 splice variant that negatively regulates Lipopolysaccharide-induced TLR4 signaling

Myeloid differentiation factor 2 (MD-2) is a secreted gp that assembles with TLR4 to form a functional signaling receptor for bacterial LPS. In this study, we have identified a novel alternatively spliced isoform of human MD-2, termed MD-2 short (MD-2s), which lacks the region encoded by exon 2 of the MD-2 gene. Similar to MD-2, MD-2s is glycosylated and secreted. MD-2s also interacted with LPS and TLR4, but failed to mediate LPS-induced NF-kappaB activation and IL-8 production. We show that MD-2s is upregulated upon IFN-gamma, IL-6, and TLR4 stimulation and negatively regulates LPS-mediated TLR4 signaling. Furthermore, MD-2s competitively inhibited binding of MD-2 to TLR4. Our study pinpoints a mechanism that may be used to regulate TLR4 activation at the onset of signaling and identifies MD-2s as a potential therapeutic candidate to treat human diseases characterized by an overly exuberant or chronic immune response to LPS.

TLR/MyD88 and liver X receptor alpha signaling pathways reciprocally control Chlamydia pneumoniae-induced acceleration of atherosclerosis

Experimental and clinical studies link Chlamydia pneumoniae infection to atherogenesis and atherothrombotic events, but the underlying mechanisms are unclear. We tested the hypothesis that C. pneumoniae-induced acceleration of atherosclerosis in apolipoprotein E (ApoE)(-/-) mice is reciprocally modulated by activation of TLR-mediated innate immune and liver X receptor alpha (LXRalpha) signaling pathways. We infected ApoE(-/-) mice and ApoE(-/-) mice that also lacked TLR2, TLR4, MyD88, or LXRalpha intranasally with C. pneumoniae followed by feeding of a high fat diet for 4 mo. Mock-infected littermates served as controls. Atherosclerosis was assessed in aortic sinuses and in en face preparation of whole aorta. The numbers of activated dendritic cells (DCs) within plaques and the serum levels of cholesterol and proinflammatory cytokines were also measured. C. pneumoniae infection markedly accelerated atherosclerosis in ApoE-deficient mice that was associated with increased numbers of activated DCs in aortic sinus plaques and higher circulating levels of MCP-1, IL-12p40, IL-6, and TNF-alpha. In contrast, C. pneumoniae infection had only a minimal effect on atherosclerosis, accumulation of activated DCs in the sinus plaques, or circulating cytokine increases in ApoE(-/-) mice that were also deficient in TLR2, TLR4, or MyD88. However, C. pneumoniae-induced acceleration of atherosclerosis in ApoE(-/-) mice was further enhanced in ApoE(-/-)LXRalpha(-/-) double knockout mice and was accompanied by higher serum levels of IL-6 and TNF-alpha. We conclude that C. pneumoniae infection accelerates atherosclerosis in hypercholesterolemic mice predominantly through a TLR/MyD88-dependent mechanism and that LXRalpha appears to reciprocally modulate and reduce the proatherogenic effects of C. pneumoniae infection.

Chlamydia pneumoniae-induced foam cell formation requires MyD88-dependent and -independent signaling and is reciprocally modulated by liver X receptor activation

Chlamydia pneumoniae is detected by macrophages and other APCs via TLRs and can exacerbate developing atherosclerotic lesions, but how that occurs is not known. Liver X receptors (LXRs) centrally control reverse cholesterol transport, but also negatively modulate TLR-mediated inflammatory pathways. We isolated peritoneal macrophages from wild-type, TLR2, TLR3, TLR4, TLR2/4, MyD88, TRIF, MyD88/TRIF, and IFN regulatory factor 3 (IRF3) KO mice, treated them with live or UV-killed C. pneumoniae in the presence or absence of oxidized LDL, then measured foam cell formation. In some experiments, the synthetic LXR agonist GW3965 was added to macrophages infected with C. pneumoniae in the presence of oxidized LDL. Both live and UV-killed C. pneumoniae induced IRF3 activation and promoted foam cell formation in wild-type macrophages, whereas the genetic absence of TLR2, TLR4, MyD88, TRIF, or IRF3, but not TLR3, significantly reduced foam cell formation. C. pneumoniae-induced foam cell formation was significantly reduced by the LXR agonist GW3965, which in turn inhibited C. pneumoniae-induced IRF3 activation, suggesting a bidirectional cross-talk. We conclude that C. pneumoniae facilitates foam cell formation via activation of both MyD88-dependent and MyD88-independent (i.e., TRIF-dependent and IRF3-dependent) pathways downstream of TLR2 and TLR4 signaling and that TLR3 is not involved in this process. This mechanism could at least partly explain why infection with C. pneumoniae accelerates the development of atherosclerotic plaque and lends support to the proposal that LXR agonists might prove clinically useful in suppressing atherogenesis.

Renal involvement as a rare complication of Dorfman-Chanarin syndrome: a case report

Dorfman-Chanarin syndrome is a rare, autosomal recessive inherited lipid storage disease with congenital ichthyotic erythroderma due to an acylglycerol recycling defect. It is characterized by accumulation of neutral lipids in different tissues. Liver, muscle, ear, eye, and central nervous system are generally involved, so we presented a patient with severe ichthyosis, lipid vacuoles in neutrophils, and multiorgan involvement including a very rare complication, renal involvement. A 7-month-old girl was presented with frequent respiratory infection, congenital ichthyotic erithroderma and suspicion for immune deficiency. On her physical examination hepatomegaly, developmental delay, palmar and plantar hyperkeratosis and increased deep tendon reflexes with clonus and high tonus were found. Laboratory investigations revealed elevation at transaminases levels, hypoalbuminemia, hypergammaglobulinemia, presence of autoantibodies and eosinophilia. Vacuolization in leukocytes confirmed Dorfman-Chanarin syndrome, whereas no mutation at RAG1-2 and ARTEMIS genes ruled-out immune deficient status of the patient. At the age of eight months the patient died from severe renal failure. Her necropsies demonstrated microvesicular lipid accumulation not only at the liver but also at the renal species. The variability of involvement of different systems in Dorfman-Chanarin syndrome is well described, however the renal findings has not been reported previously at the literature.

Serum leptin levels in patients with nasal polyposis

BACKGROUND

Nasal polyposis is one of the most common inflammatory pathologies of the nasal cavity. The aetiopathogenetic mechanisms of nasal polyp formation are still unclear.

OBJECTIVES

The aim of this study was to investigate the serum leptin levels in patients with nasal polyposis.

DESIGN

A randomised, prospective study was performed of 28 adult patients with nasal polyposis and 22 control subjects of a similar age, sex and body mass index.

RESULTS

Serum leptin levels were 12.10 +/- 9.39 ng/ml in the nasal polyposis patients and 6.17 +/- 7.68 ng/ml in the controls. A significant difference (p = 0.021) was observed in the mean serum leptin levels between nasal polyposis patients and controls.

CONCLUSION

Serum leptin levels were found to be significantly higher in patients with nasal polyposis. Leptin, apart from its primary role in the regulation of body weight and energy expenditure, may have a role in the inflammatory response of nasal polyposis.

Seroprevalence ofHelicobacter pyloriinfection in patients with chronic nonspecific pharyngitis: preliminary study

Background and objectives:

Chronic nonspecific pharyngitis is a chronic inflammation of the pharynx. It is found worldwide, and treatment is difficult. The underlying aetiopathogenesis is still controversial. The aim of this study was to investigateHelicobacter pyloriseroprevalence in chronic nonspecific pharyngitis patients without other possible causative factors for chronic pharyngeal irritation and withoutH pylorigastric mucosal infection.

Materials and methods:

Forty-one patients with symptoms of chronic nonspecific pharyngitis and 30 healthy control subjects were enrolled in this prospective, controlled, clinical study. In both study and control groups, selected patients were shown to have gastric mucosa uninfected byH pylori, as demonstrated by the 14C-urea breath test. Comprehensive otorhinolaryngological examination did not elicit any factor contributing to the chronic pharyngeal complaint. SerumH pyloriimmunoglobulin G antibody titres were assayed using serum enzyme-linked immunosorbent assay. The difference between the study and control groups was analysed by the chi-square test (the likelihood ratio was used).

Results:

Thirty-two of the 41 patients (78 per cent) and 14 of the 30 control subjects (46.7 per cent) were found to beH pyloripositive. Patients with chronic nonspecific pharyngitis were found to have a significantly higher rate ofH pyloriseropositivity than the control group (p = 0.016).

Conclusion:

These data may be important in developing future treatment strategies for chronic nonspecific pharyngitis.

MyD88 is pivotal for the early inflammatory response and subsequent bacterial clearance and survival in a mouse model of Chlamydia pneumoniae pneumonia

Chlamydia pneumoniae is the causative agent of respiratory tract infections and a number of chronic diseases. Here we investigated the involvement of the common TLR adaptor molecule MyD88 in host responses to C. pneumoniae-induced pneumonia in mice. MyD88-deficient mice were severely impaired in their ability to mount an acute early inflammatory response toward C. pneumoniae. Although the bacterial burden in the lungs was comparable 5 days after infection, MyD88-deficient mice exhibited only minor signs of pneumonia and reduced expression of inflammatory mediators. MyD88-deficient mice were unable to up-regulate proinflammatory cytokines and chemokines, demonstrated delayed recruitment of CD8+ and CD4+ T cells to the lungs, and were unable to clear the pathogen from their lungs at day 14. At day 14 the MyD88-deficent mice developed a severe, chronic lung inflammation with elevated IL-1beta and IFN-gamma leading to increased mortality, whereas wild-type mice as well as TLR2- or TLR4-deficient mice recovered from acute pneumonia and did not show delayed bacterial clearance. Thus, MyD88 is essential to recognize C. pneumoniae infection and initiate a prompt and effective immune host response against this organism leading to clearance of bacteria from infected lungs.

Mycobacterium tuberculosis heat shock proteins use diverse Toll-like receptor pathways to activate pro-inflammatory signals

Although the Toll-like receptors used by Mycobacterium tuberculosis membrane and secreted factors are known, the pathways activated by M. tuberculosis heat shock proteins are not. An efficient immune response against the intracellular pathogen M. tuberculosis is critically dependent on rapid detection of the invading pathogen by the innate immune system and coordinated activation of the adaptive immune response. Macrophage phagocytosis of M. tuberculosis is accompanied by activation of the transcription factor NF-kappaB and secretion of inflammatory mediators that play an important role in granuloma formation and immune protection during M. tuberculosis infection. The interaction between M. tuberculosis and the various Toll-like receptors is complex, and it appears that distinct mycobacterial components may interact with different members of the Toll-like receptor family. Here we show that recombinant, purified, mycobacterial heat shock proteins 65 and 70 induce NF-kappaB activity in a dose-dependent manner in human endothelial cells. Furthermore, we show that whereas mycobacterial heat shock protein 65 signals exclusively through Toll-like receptor 4, heat shock protein 70 also signals through Toll-like receptor 2. Mycobacterial heat shock protein 65-induced NF-kappaB activation was MyD88-, TIRAP-, TRIF-, and TRAM-dependent and required the presence of MD-2. A better understanding of the recognition of mycobacterial heat shock proteins and their role in the host immune response to the pathogen may open the way to a better understanding of the immunological processes induced by this important human pathogen and the host-pathogen interactions and may help in the rational design of more effective vaccines or vaccine adjuvants.

Rac1 and Toll-IL-1 Receptor Domain-Containing Adapter Protein Mediate Toll-Like Receptor 4 Induction of HIV-Long Terminal Repeat

Opportunistic infections, common in HIV-1-infected patients, increase HIV replication; however, the intracellular signaling mechanisms involved are not clearly known. We have shown that Toll-like receptor 2 (TLR2), TLR4, and TLR9 mediate microbial Ag-induced HIV-long terminal repeat (HIV-LTR) trans-activation and HIV-1 replication, and that LPS-induced HIV-LTR trans-activation is mediated through myeloid differentiation adapter protein. Recently, Toll-IL-1R domain-containing adapter protein (TIRAP) has been identified as an adapter molecule that mediates responses to TLR2 and TLR4 ligands, and TIRAP was suggested to provide signaling specificity for different TLRs. Rac1, a small GTP-binding protein that is activated upon LPS stimulation of macrophages, activates phosphatidylinositol 3-kinase and Akt and leads to NF-kappaB activation. The roles of Rac1 and TIRAP in LPS activation of HIV replication is not known. In the present study we show that LPS stimulation of human microvessel endothelial cells leads to Rac1 activation. Constitutively active Rac1 (Rac1V12) simulated the effect of LPS to activate HIV-LTR, whereas the expression of dominant negative Rac1 (Rac1N17) partially blocked LPS-induced HIV-LTR trans-activation. Rac1V12-induced HIV-LTR activation was independent of myeloid differentiation adapter protein, and dominant negative TIRAP blocked Rac1V12-induced HIV-LTR trans-activation. In this study we show for the first time that activation of Rac1 leads to HIV-LTR trans-activation, and this is mediated through TIRAP. Together these results underscore the importance of Rac1 and TIRAP in TLR4 activation of HIV replication and help delineate the signaling pathways induced by TLRs to mediate microbial Ag-induced HIV replication and HIV pathogenesis.

Chlamydial heat shock protein 60 activates macrophages and endothelial cells through Toll-like receptor 4 and MD2 in a MyD88-dependent pathway

Active inflammation and NF-kappaB activation contribute fundamentally to atherogenesis and plaque disruption. Accumulating evidence has implicated specific infectious agents including Chlamydia pneumoniae in the progression of atherogenesis. Chlamydial heat shock protein 60 (cHSP60) has been implicated in the induction of deleterious immune responses in human chlamydial infections and has been found to colocalize with infiltrating macrophages in atheroma lesions. cHSP60 might stimulate, enhance, and maintain innate immune and inflammatory responses and contribute to atherogenesis. In this study, we investigated the signaling mechanism of cHSP60. Recombinant cHSP60 rapidly activated NF-kappaB in human microvascular endothelial cells (EC) and in mouse macrophages, and induced human IL-8 promoter activity in EC. The inflammatory effect of cHSP60 was heat labile, thus excluding a role of contaminating LPS, and was blocked by specific anti-chlamydial HSP60 mAb. In human vascular EC which express Toll-like receptor 4 (TLR4) mRNA and protein, nonsignaling TLR4 constructs that act as dominant negative blocked cHSP60-mediated NF-kappaB activation. Furthermore, an anti-TLR4 Ab abolished cHSP60-induced cellular activation, whereas a control Ab had no effect. In 293 cells, cHSP60-mediated NF-kappaB activation required both TLR4 and MD2. A dominant-negative MyD88 construct also inhibited cHSP60-induced NF-kappaB activation. Collectively, our results indicate that cHSP60 is a potent inducer of vascular EC and macrophage inflammatory responses, which are very relevant to atherogenesis. The inflammatory effects are mediated through the innate immune receptor complex TLR4-MD2 and proceeds via the MyD88-dependent signaling pathway. These findings may help elucidate the mechanisms by which chronic asymptomatic chlamydial infection contribute to atherogenesis.

Detection of bacterial translocation during intestinal distension in rats using the polymerase chain reaction

To investigate whether distension causes bacterial translocation (BT), a rat model reported earlier by us was used and to detect the presence of bacterial DNA in blood by polymerase chain reaction (PCR) assay, the most sensitive detection method to date. In 4 groups of 4-week-old Wistar-albino rats a total of 15 animals each were included. In the 1st group (distension+gavage), 1010 Escherichia coli colonies were given via gavage and distension was carried out by rectal air inoculation. In the 2nd group (gavage), animals were inoculated with E. coli and no distension was induced. The 3rd group (distension) were only distended and no bacteria were inoculated. The control group were neither distended nor inoculated with E. coli. Blood samples were collected 3 h after manipulations and both blood cultures and PCR assays were performed. According to the PCR results BT was evident in 80% of group 1, 20% of group 2, and 33% of group 3 animals. BT was not determined in the control group. Significantly low percentages of positivity were observed in blood cultures in all groups (P < 0.05). These results confirm reports that BT occurs in the presence of distension and that PCR is a superior way of determining BT. Thus, it would be advisable to utilize PCR technology in cases where the possibility of distension exists, as early intervention might be useful before any severe clinical pathology (sepsis, multiple-organ-system failure) becomes evident.

Bacteriological and PCR analysis of clinical material aspirated from otitis media with effusions

Otitis media with effusions (OME) can lead to significant hearing loss in childhood. Although previous studies have shown that bacterial DNA is present in a significant percentage of effusions sterile by culture, whether the DNA represents viable organisms or 'fossilized remains' is unknown. The aim of the present study was the determination of Streptococcus pneumonia, Moraxella catarrhalis and Haemophilus influenza in the clinical materials from OME. For this purpose, effusion samples aspirated from the mid-ear were analyzed bacteriologically. Samples were also tested with polymerase chain reaction (PCR) assay. A total of 37 samples obtained from 20 patients aging between 4 and 14 were analyzed. In 17 patients, both ears demonstrated effusions, whereas in three patients, only one ear had effusions. In aerobic bacterial culture assays, nine samples (24.3%) showed bacterial growth. None of the samples were positive for anaerobic culture experiments. PCR analysis of the samples showed that 35 samples (94.5%) contained bacterial DNA. In 19 samples, only one bacterial species and in 16 samples more than one bacterial species were detected. The results of this study demonstrate that effusion fluid from otitis media cases contain a battery of bacterial species and these bacteria might play roles in the pathogens of OME. Our results indicate the PCR technique is more specific and sensitive in detection of bacteria in middle-ear effusion of OME, compared with conventional methods.

Cooperation of Toll-like receptor 2 and 6 for cellular activation by soluble tuberculosis factor and Borrelia burgdorferi outer surface protein A lipoprotein: role of Toll-interacting protein and IL-1 receptor signaling molecules in Toll-like receptor 2 signaling

Toll-like receptor 2 (TLR2) and TLR4 play important roles in innate immune responses to various microbial agents. We have previously shown that human dermal endothelial cells (HMEC) express TLR4, but very little TLR2, and respond to LPS, but not to Mycobacterium tuberculosis 19-kDa lipoprotein, unless transfected with TLR2. Here we report that HMEC are unresponsive to several additional biologically relevant TLR2 ligands, including, phenol-soluble modulin (PSM), a complex of three small secreted polypeptides from the skin commensal Staphylococcus epidermidis, soluble tuberculosis factor (STF), and Borrelia burgdorferi outer surface protein A lipoprotein (OspA-L). Expression of TLR2 renders HMEC responsive to all these ligands. We further characterized the signaling pathway in response to STF, OspA-L, and PSM in TLR2-transfected HMEC. The TLR2 signaling pathway for NF-kappaB trans-activation shares the IL-1R signaling molecules. Dominant negative constructs of TLR2 or TLR6 inhibit the responses of STF and OspA-L as well as PSM in TLR2-transfected HMEC, supporting the concept of functional cooperation between TLR2 and TLR6 for all these TLR2 ligands. Moreover, we show that Toll-interacting protein (Tollip) coimmunoprecipitates with TLR2 and TLR4 using HEK 293 cells, and overexpression of Tollip inhibits NF-kappaB activation in response to TLR2 and TLR4 signaling. Collectively, these findings suggest that there is functional interaction between TLR2 and TLR6 in the cellular response to STF and OspA-L in addition to S. epidermidis (PSM) Ags, and that engagement of TLR2 triggers a signaling cascade, which shares the IL-1R signaling molecules, similar to the TLR4-LPS signaling cascade. Our data also suggest that Tollip may be an important constituent of both the TLR2 and TLR4 signaling pathways.

Bacterial lipopolysaccharide activates HIV long terminal repeat through Toll-like receptor 4

In HIV-infected patients, concurrent infections with bacteria and viruses are known to induce HIV replication as assessed by increases in plasma HIV RNA levels. In the present study, we determined the cell surface receptor and molecular mechanisms of enterobacterial LPS-induced HIV transcription. Human dermal microvessel endothelial cells (HMEC) were transfected with an HIV-long terminal repeat (LTR)-luciferase construct and subsequently stimulated with purified bacterial LPS. Our studies demonstrate that human Toll-like receptor 4 (TLR4) mediates LPS-induced NF-kappaB and HIV-LTR activation in HMEC through IL-1 signaling molecules, namely myeloid differentiation protein, IL-1R-associated kinase, TNFR-associated factor, and NF-kappaB-inducing kinase. Cotransfection of HMEC with HIV-LTR-luciferase and TLR4 cDNA from LPS-hyporesponsive C3H/HeJ mice abrogates LPS-induced HIV transcription as does the use of dominant-negative mutants of the IL-1 signaling molecules. Transfection of HMEC with an HIV-LTR-mutant that lacks the NF-kappaB binding site or pretreatment of cells with chemical inhibitors of the NF-kappaB pathway also blocked LPS-induced HIV-LTR transactivation. These data support the conclusion that TLR4 mediates enterobacterial LPS-induced HIV transcription via IL-1 signaling molecules and NF-kappaB activation plays an important role in HIV-LTR transactivation.

Cholinesterase activity is similar in C3H/HeJ and A/J mice and does not account for their different bronchoconstrictor responsiveness

Significant interstrain variation in airway responsiveness to acetylcholine (ACh) exists in inbred mouse strains. We hypothesized that part of the variation may be due to between-strain differences in cholinesterase activity. We asked if administration of neostigmine (an acetylcholinesterase inhibitor) and/or succinylcholine (an agent which competes for and inhibits butyrylcholinesterase) altered ACh responsiveness in hyporesponsive C3H/HeJ and hyperresponsive A/J mouse strains. Airway responses to ACh were measured by the airway pressure time index in the presence and absence of succinylcholine (10 mg/kg) and/or neostigmine (0.7 mg/kg). In addition, acetylcholinesterase and butyrylcholinesterase activity were directly measured. Acetylcholinesterase and butyrylcholinesterase inhibition increased airway responses to acetylcholine in both strains, but did not eliminate or decrease the differences in airway responsiveness to ACh previously seen in the two strains. Cholinesterase activities in the two strains were not significantly different. We conclude that differences in either acetylcholinesterase or butyrylcholinesterase in the A/J or C3H/HeJ mouse strains are unlikely to contribute to the differences in airway responsiveness to exogenously administered cholinergic agonists.

Effect of lung inflation in vivo on airways with smooth muscle tone or edema

Fibrous attachments to the airway wall and a subpleural surrounding pressure can create an external load against which airway smooth muscle must contract. A decrease in this load has been proposed as a possible cause of increased airway narrowing in asthmatic individuals. To study the interaction between the airways and the surrounding lung parenchyma, we investigated the effect of lung inflation on relaxed airways, airways contracted with methacholine, and airways made edematous by infusion of bradykinin into the bronchial artery. Measurements were made in anesthetized sheep by using high-resolution computed tomography to visualize changes in individual airways. During methacholine infusion, airway area was decreased but increased minimally with increases in transpulmonary pressure. Bradykinin infusion caused a 50% increase in airway wall area and an small decrease in airway luminal area. In contrast to airways contracted with methacholine, the luminal area after bradykinin increased substantially with increases in transpulmonary pressure, reaching 99% of the relaxed area at total lung capacity. Thus airway edema by itself did not prevent full distension of the airway at lung volumes approaching total lung capacity. Therefore, we speculate that if a deep inspiration fails to relieve airway narrowing in vivo, this must be a manifestation of airway smooth muscle contraction and not airway wall edema.

Prevention of lidocaine aerosol-induced bronchoconstriction with intravenous lidocaine

BACKGROUND

Lidocaine applied topically provokes bronchoconstriction in persons with hyperreactive airway disease. The authors questioned whether intravenous lidocaine would prevent lidocaine-aerosol induced bronchoconstriction. They compared the effects of lidocaine administered intravenously and by the aerosol route on baseline airway tone, and on the prevention of histamine-induced bronchoconstriction in five Basenji-Greyhound dogs.

METHODS

Dogs were pretreated with either intravenous or aerosol lidocaine followed by histamine aerosol challenge. On separate days, dogs were pretreated with intravenous lidocaine, followed by aerosol lidocaine administration at similar doses. Airway caliber was assessed using high-resolution computed tomography. Data were analyzed by two-way analysis of variance. Serum lidocaine concentrations were obtained.

RESULTS

Histamine alone decreased the airway area by 32 +/- 3%. Lidocaine administered intravenously or by the aerosol route significantly inhibited histamine-induced bronchoconstriction. There was no significant difference between the two routes in preventing histamine-induced bronchoconstriction. At the dose that inhibited histamine-induced bronchoconstriction, lidocaine administered by the aerosol route decreased baseline airway area by 27 +/- 3% (P < 0.01), whereas intravenous lidocaine had no effect. Intravenous lidocaine prevented lidocaine aerosol-induced bronchoconstriction, and the combination of intravenous and aerosol lidocaine significantly dilated the airways by 20 +/- 5% (P < 0.01 compared with control).

CONCLUSIONS

An intravenous bolus of lidocaine prevents the initial bronchoconstriction induced by lidocaine when administered as an aerosol.