Severe pneumonia mortality in elderly patients is associated with downregulation of Toll-like receptors 2 and 4 on monocytes

Innate immune responses in pneumonia

The lungs are an immunologically unique environment; they are exposed to innumerable pathogens and particulate matter daily. Appropriate clearance of pathogens and response to pollutants is required to prevent overwhelming infection, while preventing tissue damage and maintaining efficient gas exchange. Broadly, the innate immune system is the collection of immediate, intrinsic immune responses to pathogen or tissue injury. In this review, we will examine the innate immune responses of the lung, with a particular focus on their role in pneumonia. We will discuss the anatomic barriers and antimicrobial proteins of the lung, pathogen and injury recognition, and the role of leukocytes (macrophages, neutrophils, and innate lymphocytes) and lung stromal cells in innate immunity. Throughout the review, we will focus on new findings in innate immunity as well as features that are unique to the lung.

Potential value of pharmacological agents acting on toll-like receptor (TLR) 7 and/or TLR8 in COVID-19

The COVID-19 pandemic is an ongoing global pandemic of coronavirus disease 2019 as an atypical type of viral pneumonia caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Many potential pharmacotherapies are currently being investigated against this disease. This article points to and justifies, the importance of investigating the potential therapeutic value of pharmacological agents acting on Toll-like Receptor (TLR) 7 and/or TLR8 as double-edged swords combating COVID-19. Induction of TLR7 and/or TLR8 may be investigated as a strategy to stimulate immunity and may be added to anti-COVID19 vaccines to cope with their current viral escape challenge. TLR7 stimulation may not only help viral clearance through Th1 antiviral responses but may also provide beneficial broncho- and vaso-dilatory, as well as, anti-inflammatory effects. Pharmacological compounds acting as TLR7 and/or TLR8 agonists may be of value if used by frontline healthcare workers with comorbidities who demonstrate mild symptoms of the disease. On the other hand, TLR7 and/or TLR8 antagonists may be used in combination with immune-modulatory/anti-inflammatory drugs in severe cases of the disease, with potential synergistic effects that could also help in reducing the doses of such therapies, and consequently their adverse effects.

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There is potential value in development of TLR7/8 agonists/antagonists as double-edged swords combating COVID-19.

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TLR7/8 agonists, as immune-stimulants in mild disease, may also be added to preventive vaccines acting against viral escape.

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TLR7/8 antagonists may be combined with immune-suppressants in severe cases for potential synergism and minimized toxicity.

Pneumococcal colonization impairs mucosal immune responses to live attenuated influenza vaccine

Influenza virus infections affect millions of people annually, and current available vaccines provide varying rates of protection. However, the way in which the nasal microbiota, particularly established pneumococcal colonization, shape the response to influenza vaccination is not yet fully understood. In this study, we inoculated healthy adults with live Streptococcuspneumoniae and vaccinated them 3 days later with either tetravalent-inactivated influenza vaccine (TIV) or live attenuated influenza vaccine (LAIV). Vaccine-induced immune responses were assessed in nose, blood, and lung. Nasal pneumococcal colonization had no impact upon TIV-induced antibody responses to influenza, which manifested in all compartments. However, experimentally induced pneumococcal colonization dampened LAIV-mediated mucosal antibody responses, primarily IgA in the nose and IgG in the lung. Pulmonary influenza-specific cellular responses were more apparent in the LAIV group compared with either the TIV or an unvaccinated group. These results indicate that TIV and LAIV elicit differential immunity to adults and that LAIV immunogenicity is diminished by the nasal presence of S. pneumoniae. Therefore, nasopharyngeal pneumococcal colonization may affect LAIV efficacy.

Evidence-Based Complementary and Alternative Medicine Exploring Active Components and Mechanism of Jinhua Qinggan Granules in Treatment of COVID-19 Based on Virus-Host Interaction

This study aimed at exploring the active components and mechanisms of Jinhua Qinggan granules (JQG) in the prevention and treatment of coronavirus disease 2019 (COVID-19) using network pharmacology and molecular docking technology. These efforts were accomplished by employing the holistic approach of traditional Chinese medicine (TCM) and considering the virus-host interaction consisting of viral characteristics, the entry pathway into the host, and the resulting immune response. The chemical constituents and molecular targets of the 12 herbs from JQG were obtained using the TCM Systems Pharmacology database and analysis platform. UniProt was used to search for genes corresponding to JQG protein targets and Cytoscape 3.7.2 to construct the component-target (gene) network. Database for Annotation, Visualization and Integrated Discovery was used to perform enrichment analysis of gene ontology functions and the Kyoto Encyclopedia of Genes and Genomes pathways to predict the mechanism of action. The components ranked high in the network, and the major active components of the principal medicines, based on published literature, were docked with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) 3CL hydrolase, SARS-CoV-2 spike glycoprotein (S protein), angiotensin conversion enzyme II (ACE2), and suppressor of cytokine signaling 1 (SOCS1). Visualization analysis demonstrated that the core active components of JQG had a strong affinity for SARS-CoV-2 3CL hydrolase, SARS-CoV-2 S protein, ACE2, and SOCS1. These data imply that the potential active components of JQG may act on multiple signaling pathways by binding to targets such as SARS-CoV-2 3CL hydrolase, S protein, ACE2, and SOCS1, thereby inhibiting virus replication and targeting cell binding, reducing host inflammation, and activating antiviral immunity to a certain extent.

Altered Toll-Like Receptor Signalling in Children with Down Syndrome

Toll-like receptors (TLRs) are the key in initiating innate immune responses. TLR2 is crucial in recognising lipopeptides from gram-positive bacteria and is implicated in chronic inflammation. Children with Down syndrome (DS) are prone to infections from these pathogens and have an increased risk of autoimmunity. Sparstolonin B (SsnB) is a TLR antagonist which attenuates cytokine production and improves outcomes in sepsis. We hypothesised that TLR signalling may be abnormal in children with DS and contribute to their clinical phenotype. We evaluated TLR pathways in 3 ways: determining the expression of TLR2 on the surface of neutrophils and monocytes by flow cytometry, examining the gene expression of key regulatory proteins involved in TLR signal propagation, MyD88, IRAK4, and TRIF, by quantitative PCR, and lastly determining the cytokine production by ELISA following immunomodulation with proinflammatory stimuli (lipopolysaccharide (LPS), Pam3Csk4) and the anti-inflammatory agent SsnB. We report TLR2 expression being significantly increased on neutrophils, total monocytes, and intermediate and nonclassical monocytes in children with DS (n = 20, mean age 8.8 ± SD 5.3 years, female n = 11) compared to controls (n = 15, mean age 6.2 ± 4.2 years, female n = 5). At baseline, the expression of MyD88 was significantly lower, and TRIF significantly raised in children with DS. The TLR antagonist SsnB was effective in reducing TLR2 and CD11b expression and abrogating cytokine production in both cohorts. We conclude that TLR signalling and the TLR2 pathway are dysregulated in DS, and this disparate innate immunity may contribute to chronic inflammation in DS. SsnB attenuates proinflammatory mediators and may be of therapeutic benefit.

The Systemic Lupus Erythematosus Infection Predictive Index (LIPI): A Clinical-Immunological Tool to Predict Infections in Lupus Patients

Among autoimmune diseases, systemic lupus erythematosus (SLE) patients have a unique predisposition to develop infections, which represents one of their main causes of morbidity and mortality. Many infections occur at disease diagnosis in the absence of immunosuppressive therapy, suggesting that the immunological abnormalities in SLE patients might be fundamental for the development of this complication. The aim of this study was to address the main clinical and immunological features associated with the development of infection and to create and validate a compound clinical-immunological infection predictive index in a cohort of SLE patients. We included 55 SLE patients with < 5 years since diagnosis. The clinical and immunological features were evaluated periodically and patients were followed-up during 1 year, searching for the development of infection. Immunophenotyping was performed by multiparametric flow cytometry and neutrophil extracellular traps (NETs) were assessed by confocal microscopy. Eighteen patients (32.7%) presented 19 infectious events, 5 (26.3%) were severe. For the construction of the index, we performed a logistic regression analysis and the cutoff points were determined with ROC curves. Increased numbers of peripheral Th17 cells, B cell lymphopenia, and lower TLR2 expression in monocytes, as well as the use of cyclophosphamide were the major risk factors for the development of infection and thus were included in the index. Besides, patients that developed infection were characterized by increased numbers of low-density granulocytes (LDGs) and higher expression of LL-37 in NETs upon infection. Finally, we validated the index retrospectively in a nested case-control study. A score >1.5 points was able to predict infection in the following year (AUC = 0.97; LR- = 0.001, specificity 100%, P = 0.0003). Our index encompasses novel immunological features able to prospectively predict the risk of infection in SLE patients.

Emergency treatment and nursing of children with severe pneumonia complicated by heart failure and respiratory failure: 10 case reports

Pneumonia refers to lung inflammation caused by different pathogens or other factors, and is a common pediatric disease occurring in infants and young children. It is closely related to the anatomical and physiological characteristics of infants and young children and is more frequent during winter and spring, or sudden changes in temperature. Pneumonia is a serious disease that poses a threat to children's health and its morbidity and mortality rank first, accounting for 24.5-65.2% of pediatric inpatients. Due to juvenile age, severe illness and rapid changes, children often suffer acute heart failure, respiratory failure and even toxic encephalopathy at the same time. The concurrence in different stages of the process of emergency treatment tends to relapse, which directly places the lives of these children at risk. Severe pneumonia constitutes one of the main causes of infant mortality. In the process of nursing children with severe pneumonia, intensive care was provided, including condition assessment and diagnosis, close observation of disease, keeping the airway unblocked, rational oxygen therapy, prevention and treatment of respiratory and circulatory failure, support of vital organs, complications, and health education. The inflammatory response was proactively controlled, to prevent suffocation and reduce mortality. In summary, positive and effective nursing can promote the rehabilitation of children patients, which can be reinforced with adequate communication with the parents and/or caretakers.

Association between TLR4 A299G polymorphism and pneumonia risk: a meta-analysis

Background

Several genetic studies have evaluated the association between Toll-like receptor 4 (TLR4) A299G polymorphism and the risk of pneumonia. However, the results were not consistent. We thus did this meta-analysis.

Material/Methods

Relevant studies were systematically searched by using the NCBI, Medline, Web of Science, and Embase databases. Data were extracted independently by 2 investigators. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated.

Results

Eight case-control studies with 658 patients and 1862 controls were included in this meta-analysis. TLR4 A299G polymorphism was significantly associated with pneumonia risk (OR=1.74; 95% CI 1.19–2.53; P=0.004). The result was significant in adults. In addition, TLR4 A299G polymorphism was also associated with community-acquired pneumonia (CAP) risk. Results from cumulative meta-analysis and sensitivity analysis suggested that the results are reliable and robust.

Conclusions

The results of this meta-analysis suggest that susceptibility to pneumonia was associated with TLR4 A299G polymorphism.

Polymorphisms of Toll-like receptors (TLR2 and TLR4) are associated with the risk of infectious complications in acute myeloid leukemia

Infectious complications continue to be one of the major causes of morbidity and mortality in patients with acute myeloid leukemia (AML). Several single-nucleotide polymorphisms (SNPs) of Toll-like receptors (TLRs) can affect the genetic susceptibility to infections or even sepsis. We sought to investigate the impact of different SNPs on the incidence of developing sepsis and pneumonia in patients with newly diagnosed AML following induction chemotherapy. We analyzed three SNPs in the TLR2 (Arg753Gln) and TLR4 (Asp299Gly and Thr399Ile) gene in a cohort of 155 patients with AML who received induction chemotherapy. The risk of developing sepsis and pneumonia was assessed by multiple logistic regression analyses. The presence of the TLR2 Arg753Gln polymorphism was significantly associated with pneumonia in AML patients (odds ratio (OR): 10.78; 95% confidence interval (CI): 2.0-58.23; P=0.006). Furthermore, the cosegregating TLR4 polymorphisms Asp299Gly and Thr399Ile were independent risk factors for the development of both sepsis and pneumonia (OR: 3.55; 95% CI: 1.21-10.4, P=0.021 and OR: 3.57, 95% CI: 1.3-9.86, P=0.014, respectively). To our best knowledge, this study represents the first analysis demonstrating that polymorphisms of TLR2 and TLR4 influence the risk of infectious complications in patients with AML undergoing induction chemotherapy.

Lung cell-specific modulation of LPS-induced TLR4 receptor and adaptor localization

Lung infection by Gram-negative bacteria is a major cause of morbidity and mortality in humans. Lipopolysaccharide (LPS), located in the outer membrane of the Gram-negative bacterial cell wall, is a highly potent stimulus of immune and structural cells via the TLR4/MD2 complex whose function is sequentially regulated by defined subsets of adaptor proteins. Regulatory mechanisms of lung-specific defense pathways point at the crucial role of resident alveolar macrophages, alveolar epithelial cells, the TLR4 receptor pathway, and lung surfactant in shaping the innate immune response to Gram-negative bacteria and LPS. During the past decade intracellular spatiotemporal localization of TLR4 emerged as a key feature of TLR4 function. Here, we briefly review lung cell type- and compartment-specific mechanisms of LPS-induced TLR4 regulation with a focus on primary resident hematopoietic and structural cells as well as modifying microenvironmental factors involved.

Parainfluenza virus lower respiratory tract disease after hematopoietic cell transplant: viral detection in the lung predicts outcome

BACKGROUND

Parainfluenza virus (PIV) commonly infects patients following hematopoietic cell transplantation (HCT), frequently causing lower respiratory tract disease (LRTD). The definition of LRTD significantly differs among studies evaluating the impact of PIV after HCT.

METHODS

We retrospectively evaluated 544 HCT recipients with laboratory-confirmed PIV and classified LRTD into 3 groups: possible (PIV detection in upper respiratory tract with new pulmonary infiltrates with/without LRTD symptoms), probable (PIV detection in lung with LRTD symptoms without new pulmonary infiltrates), and proven (PIV detection in lung with new pulmonary infiltrates with/without LRTD symptoms).

RESULTS

Probabilities of 90-day survival after LRTD were 87%, 58%, and 45% in possible, probable, and proven cases, respectively. Patients with probable and proven LRTD had significantly worse survival than those with upper respiratory tract infection (probable: hazard ratio [HR], 5.87 [P < .001]; proven: HR, 9.23 [P < .001]), whereas possible LRTD did not (HR, 1.49 [P = .27]). Among proven/probable cases, oxygen requirement at diagnosis, low monocyte counts, and high-dose steroid use (>2 mg/kg/day) were associated with high mortality in multivariable analysis.

CONCLUSIONS

PIV LRTD with viral detection in lungs (proven/probable LRTD) was associated with worse outcomes than was PIV LRTD with viral detection in upper respiratory samples alone (possible LRTD). This new classification should impact clinical trial design and permit comparability of results among centers.