Tryptophan catabolism via the kynurenine pathway regulates infection and inflammation: from mechanisms to biomarkers and therapies.

BACKGROUND: L-Tryptophan (L-Trp), an essential amino acid, is the only amino acid whose level is regulated specifically by immune signals. Most proportions of Trp are catabolized via the kynurenine (Kyn) pathway (KP) which has evolved to align the food availability and environmental stimulation with the host pathophysiology and behavior. Especially, the KP plays an indispensable role in balancing the immune activation and tolerance in response to pathogens. SCOPE OF REVIEW: In this review, we elucidate the underlying immunological regulatory network of Trp and its KP-dependent catabolites in the pathophysiological conditions by participating in multiple signaling pathways. Furthermore, the KP-based regulatory roles, biomarkers, and therapeutic strategies in pathologically immune disorders are summarized covering from acute to chronic infection and inflammation. MAJOR CONCLUSIONS: The immunosuppressive effects dominate the functions of KP induced-Trp depletion and KP-produced metabolites during infection and inflammation. However, the extending minor branches from the KP are not confined to the immune tolerance, instead they go forward to various functions according to the specific condition. Nevertheless, persistent efforts should be made before the clinical use of KP-based strategies to monitor and cure infectious and inflammatory diseases.

Complement-pentraxins synergy: Navigating the immune battlefield and beyond.

The complement is a crucial immune defense system that triggers rapid immune responses and offers efficient protection against foreign invaders and unwanted host elements, acting as a sentinel. Activation of the complement system occurs upon the recognition of pathogenic microorganisms or altered self-cells by pattern-recognition molecules (PRMs) such as C1q, collectins, ficolins, and pentraxins. Recent accumulating evidence shows that pentraxins establish a cooperative network with different classes of effector PRMs, resulting in synergistic effects in complement activation. This review describes the complex interaction of pentraxins with the complement system and the implications of this cooperative network for effective host defense during pathogen invasion.

Loss of CFTR function in macrophages alters the cell transcriptional program and delays lung resolution of inflammation.

Cystic fibrosis (CF) is an autosomal recessive genetic disorder caused by mutations in the CF Transmembrane-conductance Regulator (CFTR) gene. The most severe pathologies of CF occur in the lung, manifesting as chronic bacterial infection, persistent neutrophilic inflammation, and mucopurulent airway obstruction. Despite increasing knowledge of the CF primary defect and the resulting clinical sequelae, the relationship between the CFTR loss of function and the neutrophilic inflammation remains incompletely understood. Here, we report that loss of CFTR function in macrophages causes extended lung inflammation. After intratracheal inoculation with Pseudomonas aeruginosa, mice with a macrophage-specific Cftr-knockout (Mac-CF) were able to mount an effective host defense to clear the bacterial infection. However, three days post-inoculation, Mac-CF lungs demonstrated significantly more neutrophil infiltration and higher levels of inflammatory cytokines, suggesting that Mac-CF mice had a slower resolution of inflammation. Single-cell RNA sequencing revealed that absence of CFTR in the macrophages altered the cell transcriptional program, affecting the cell inflammatory and immune responses, antioxidant system, and mitochondrial respiration. Thus, loss of CFTR function in macrophages influences cell homeostasis, leading to a dysregulated cellular response to infection that may exacerbate CF lung disease.

Geriatric Phenotypes and Their Impact on Oral Health.

Older adults have multiple morbidities that can impact oral, systemic, and psychological health. Although each disorder requires consideration from the provider before treatment, by assessing the common phenotypic presentations of older adults, we can better understand, select, and coordinate treatment modifications that would need to be considered and implemented for dental care.

Empyema necessitans: After recent thoracostomy in an immunocompromised patient.

This paper consists of a clinical image of an unexpected complication of a pleural space infection that dissects through the pleura into the soft tissues of the chest in an immunocompromised patient.

Association Between Empirical Anti-Pseudomonal Antibiotics for Recurrent Lower Respiratory Tract Infections and Mortality: A Retrospective Cohort Study.

Purpose: Whether the empirical use of anti-pseudomonal antibiotics actually improves patient outcomes is unclear. Hence, we aimed to determine whether empirical anti-pseudomonal antibiotics are better than anti-pseudomonal antibiotics in treating patients with recurrent lower respiratory tract infections (LRTIs). Patients and Methods: We extracted data from the Japanese nationwide database of the Real World Data Co., Ltd. Our target population was patients with LRTIs, defined as chronic obstructive pulmonary disease exacerbation and pneumonia. We included patients aged ≥40 years who were admitted for lower respiratory tract infections ≥2 times within 90 days. We excluded patients who had an event (death or transfer) within 24 h after admission. We ran a frailty model adjusted for the following confounding factors: number of recurrences, age, body mass index, activities of daily living, Hugh-Johns classification, altered mental status, oxygen use on admission, blood urea nitrogen, and systemic steroid use. Results: We included 893 patients with 1362 observations of recurrent LRTIs. There were 897 (66%) observations in the non-anti-pseudomonal antibiotic group and 465 (34%) in the anti-pseudomonal group; the numbers of in-hospital deaths were 86/897 (10%) and 63/465 (14%), respectively. Our frailty model yielded an adjusted hazard ratio (HR) (anti-pseudomonal group/non-anti-pseudomonal group) of 1.49 (95% confidence interval, 1.03-2.14). Conclusion: The empirical use of anti-pseudomonal antibiotics was associated with a higher HR of in-hospital mortality than the use of non-anti-pseudomonal antibiotics. Physicians might need to consider limiting the prescription of anti-pseudomonal antibiotics based on background factors such as the patient's baseline function and disease severity. Further studies are needed to evaluate the causal relationship between empirical anti-pseudomonal antibiotics and mortality, and identify specific patient population who benefit from empirical anti-pseudomonal antibiotics.

Automatic Identification of Myeloperoxidase Natural Inhibitors in Plant Extracts.

The aim of this study is the development of an automated method for myeloperoxidase activity evaluation and its application in testing the inhibitory action of different plant extracts on the activity of the enzyme. This enzyme has its concentration increased in inflammatory and infectious processes, so it is a possible target to limit these processes. Therefore, an automatic sequential in-jection analysis (SIA) system was optimized and demonstrated that it is possible to obtain results with satisfactory accuracy and precision. With the developed method, plant extracts were studied, as promising candidates for MPO inhibition. In the group of selected plant extracts, IC50 values from 0.029 ± 0.002 mg/mL to 35.4 ± 3.5 mg/mL were obtained. Arbutus unedo L. proved to be the most inhibitory extract for MPO based on its phenolic compound content. The coupling of an automatic SIA method to MPO inhibition assays is a good alternative to other conventional methods, due to its simplicity and speed. This work also supports the pharmacological use of these species that inhibit MPO, and exhibit activity that may be related to the treatment of infection and inflammation.

Report of the 24th Meeting on Signal Transduction 2021.

The annual meeting "Signal Transduction-Receptors, Mediators and Genes" of the Signal Transduction Society (STS) is an interdisciplinary conference which is open to all scientists sharing a common interest in the elucidation of the signaling pathways mediating physiological or pathological processes in the health and disease of humans, animals, plants, fungi, prokaryotes, and protists. The 24th meeting on signal transduction was held from 15 to 17 November 2021 in Weimar, Germany. As usual, keynote presentations by invited scientists introduced the respective workshops, and were followed by speakers chosen from the submitted abstracts. A special workshop focused on "Target Identification and Interaction". Ample time was reserved for the discussion of the presented data during the workshops. Unfortunately, due to restrictions owing to the SARS-CoV-2 pandemic, the poster sessions-and thus intensive scientific discussions at the posters-were not possible. In this report, we provide a concise summary of the various workshops and further aspects of the scientific program.

Outcomes associated with antibiotic administration for isolated maternal fever in labor.

BACKGROUND: The American College of Obstetricians and Gynecologists currently recommends that antibiotic treatment should be considered for women with isolated maternal fevers during labor. However, there is little known about the maternal and neonatal impact of antibiotic treatment in this scenario. OBJECTIVE: We sought to assess the outcomes in women with a nonsustained, isolated maternal fever treated with antibiotics and compare it with expectant management. STUDY DESIGN: This was a retrospective cohort study of laboring women with a singleton gestation at term and a single temperature of between 38.0°C and 38.9°C without other evidence of infection (leukocytosis >15,000/mm3, fetal tachycardia, malodorous amniotic fluid, suspected alternate source of infection) at a tertiary teaching hospital. A contemporaneously maintained, validated obstetrical database was used to identify women for our cohort. Women with rheumatologic or renal disease, nongestational diabetes, preterm labor, placental abruption, vaginal bleeding, HIV, malpresentation, and fetal anomalies were excluded. The primary outcome was a postpartum fever above 38.0°C. Secondary maternal outcomes were treatment for postpartum endometritis, uterine atony, postpartum hemorrhage, admission to the intensive care unit, and postpartum length of stay. Secondary neonatal outcomes were neonatal intensive care unit admission, 5-minute Apgar score of <7, 5-minute Apgar score of <4, neonatal intensive care unit length of stay, and neonatal antibiotic administration. The results were compared using univariable and multivariable analyses. RESULTS: From January 1, 2015, to December 31, 2018, 359 women were identified; 85 received antibiotics and 274 did not. The baseline characteristics were similar between the groups, except for gestational age at the time of delivery (39.2 weeks vs 39.5 weeks for the antibiotic and no antibiotic groups, respectively; P=.02). The incidence in postpartum fever showed a downward trend in the antibiotic group (10.59% for the antibiotic group vs 18.98% for the no antibiotic group; P=.07). Significantly fewer women in the antibiotic group were treated for postpartum endometritis (3.53% vs 11.31%; P=.03). Neonatal intensive care unit admission and neonatal antibiotic administration rates were higher in the antibiotic group (41.18% vs 17.88%; P<.001 and 36.47% vs 12.41%; P<.001, respectively). The incidence of 5-minute Apgar score of <7 was higher in the antibiotic group (8.25% vs 2.19%; P=.016). After controlling for age, gestational age, body mass index, group B streptococci status, delivery method, parity, administration of epidural, and receipt of acetaminophen, the odds for postpartum fever were reduced by a factor of 0.42 (95% confidence interval, 0.18-0.99) among women who received antibiotics when compared with those who did not receive antibiotics. Outcome results are presented in Table 2. CONCLUSION: Although there was a lower rate of treatment for endometritis among women who received antibiotics for a single isolated maternal fever, there was a higher rate of neonatal intensive care unit admissions and 5-minute Apgar score of <7. This indicates that there likely is maternal benefit associated with antibiotic use, however, there are concerns about the neonatal risk.

Stereoselective Synthesis, Configurational Assignment and Biological Evaluations of the Lipid Mediator RvD2n-3 DPA.

Herein we report the first total synthesis of RvD2n-3 DPA , an endogenously formed mediator biosynthesized from the omega-3 fatty acid n-3 docosapentaenoic acid. The key steps are the Midland Alpine borane reduction, Sonogashira cross-coupling reactions, and a Z-selective alkyne reduction protocol, yielding RvD2n-3 DPA methyl ester in 13 % yield over 12 steps (longest linear sequence). The physical property data (UV chromophore, chromatography and MS/MS fragmentation) of the synthetic lipid mediator matched those obtained from biologically produced material. Moreover, synthetic RvD2n-3 DPA also carried the potent biological activities of enhancing macrophage uptake of Staphylococcus aureus and zymosan A bioparticles.

Aging influences the cardiac macrophage phenotype and function during steady state and during inflammation.

Aging-mediated immune dysregulation affects the normal cardiac immune cell phenotypes and functions, resulting in cardiac distress. During cardiac inflammation, immune activation is critical for mounting the regenerative responses to maintain normal heart function. We investigated the impact of aging on myeloid cell phenotype and function during cardiac inflammation induced by a sub-lethal dose of LPS. Our data show that hearts of old mice contain more myeloid cells than the hearts of young mice. However, while the number of monocytic-derived suppressor cells did not differ between young and old mice, monocytic-derived suppressor cells from old mice were less able to suppress T-cell proliferation. Since cardiac resident macrophages (CRMs) are important for immune surveillance, clearance of dead cells, and tissue repair, we focused our studies on CRMs phenotype and function during steady state and LPS treatment. In the steady state, we observed significantly more MHC-IIlow and MHC-IIhigh CRMs in the hearts of old mice; however, these populations were decreased in both young and aged mice upon LPS treatment and the decrease in CRM populations correlated with defects in cardiac electrical activity. Notably, mice treated with a liver X receptor (LXR) agonist showed an increase in MerTK expression in CRMs of both young and old mice, which resulted in the reversal of cardiac electrical dysfunction caused by lipopolysaccharide (LPS). We conclude that aging alters the phenotype of CRMs, which contributes to the dysregulation of cardiac electrical dysfunction during infection in aged mice.

Leukocyte Activation Profile Assessed by Raman Spectroscopy Helps Diagnosing Infection and Sepsis.

OBJECTIVES: Leukocytes are first responders to infection. Their activation state can reveal information about specific host immune response and identify dysregulation in sepsis. This study aims to use the Raman spectroscopic fingerprints of blood-derived leukocytes to differentiate inflammation, infection, and sepsis in hospitalized patients. Diagnostic sensitivity and specificity shall demonstrate the added value of the direct characterization of leukocyte's phenotype. DESIGN: Prospective nonrandomized, single-center, observational phase-II study (DRKS00006265). SETTING: Jena University Hospital, Germany. PATIENTS: Sixty-one hospitalized patients (19 with sterile inflammation, 23 with infection without organ dysfunction, 18 with sepsis according to Sepsis-3 definition). INTERVENTIONS: None (blood withdrawal). MEASUREMENTS AND MAIN RESULTS: Individual peripheral blood leukocytes were characterized by Raman spectroscopy. Reference diagnostics included established clinical scores, blood count, and biomarkers (C-reactive protein, procalcitonin and interleukin-6). Binary classification models using Raman data were able to distinguish patients with infection from patients without infection, as well as sepsis patients from patients without sepsis, with accuracies achieved with established biomarkers. Compared with biomarker information alone, an increase of 10% (to 93%) accuracy for the detection of infection and an increase of 18% (to 92%) for detection of sepsis were reached by adding the Raman information. Leukocytes from sepsis patients showed different Raman spectral features in comparison to the patients with infection that point to the special immune phenotype of sepsis patients. CONCLUSIONS: Raman spectroscopy can extract information on leukocyte's activation state in a nondestructive, label-free manner to differentiate sterile inflammation, infection, and sepsis.

Potential Prenatal Origins of Necrotizing Enterocolitis.

Necrotizing enterocolitis is a serious and yet incompletely understood gastrointestinal disease of infancy that predominately impacts premature neonates. Prevention is a key strategy for the management of necrotizing enterocolitis. Although postnatal risk factors have been the focus of prevention efforts, obstetric complications, including intrauterine inflammation and infection, growth restriction, preeclampsia, and prenatal medications, have been associated with an increased risk of necrotizing enterocolitis. This article reviews the evidence behind the prenatal risk factors for necrotizing enterocolitis, and discusses how these risk factors may elucidate the pathogenesis of necrotizing enterocolitis and provide insight into prevention and treatment.

Comparison of early postoperative cytokine changes in patients undergoing intubated and non-intubated thoracic surgery: a randomized controlled trial.

OBJECTIVES: The inflammatory response after surgery is associated with patient prognosis. Patients who undergo thoracic surgery exhibit a profound systemic inflammatory response due to the surgical procedures used and application of one-lung ventilation. The aim of this study was to compare perioperative inflammatory changes in patients after intubated and non-intubated thoracic surgery for primary lung cancer resection. METHODS: This prospective randomized controlled study included forty patients who underwent surgical resection for stage I non-small-cell lung cancer. Blood samples for cytokine analysis were collected just before induction, at 1 and 24 h after surgery. Levels of the pro-inflammatory cytokine and anti-inflammatory cytokines were measured using quantitative sandwich enzyme immunoassay kits. RESULTS: The basal values of cytokines were comparable between 2 groups. Within each group, the postoperative levels of interleukin (IL)-1, IL-6 and tumour necrosis factor-α increased, while those of IL-4 and IL-10 did not change significantly. The levels of IL-6 and tumour necrosis factor-α were significantly lower in group NI at 1 and 24 h postoperatively. Other cytokines did not differ in both groups during postoperative period. The IL-6/IL-10 ratio at 1 h after surgery was lower in non-intubated patients than in intubated patients, but there was no difference at 24 h after surgery. CONCLUSIONS: Non-intubated thoracic surgery may attenuate the early inflammatory cytokine changes following major resection for primary lung cancer compared with intubated conventional surgery. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov registry number NCT04007354.

High parathyroid hormone predicts exacerbations in COPD patients with hypovitaminosis D.

BACKGROUND: Hypovitaminosis D has been linked to deterioration in clinical parameters and lung function in COPD. As a response to low levels of vitamin D serum Parathyroid Hormone (iPTH) is increased in some, but not all, patients. The aim of this study was to determine whether COPD patients with elevated PTH levels are at higher risk of COPD exacerbations and hospitalizations. METHODS: 166 COPD outpatients were randomly preselected. Clinical and analytical characteristics were assessed at baseline. After excluding patients with other conditions known to disturb calcium metabolism 141 patients were identified. Except one, all patients were prospectively followed for 12 months after obtaining the blood samples. Hypovitaminosis D was considered when serum 25(OH)D < 30 ng/mL. Secondary hyperparathyroidism was considered when serum iPTH was higher than normal (50 pg/mL) in patients with hypovitaminosis D. COPD exacerbations and hospital admissions were recorded during the follow-up. RESULTS: Prevalence of hypovitaminosis D in COPD patients was 89.3%, prevalence of secondary hyperparathyroidism associated with hypovitaminosis D was 22,9%. Cox proportional risk analysis showed that patients belonging to the high iPTH-low 25(OH)D group were at a higher risk of moderate COPD exacerbations (HR 1.81 (CI95% 1.043-3.127), p = 0.035) and hospital admissions (HR 5.45 (CI95% 2.018-14.720), p = 0.002) as compared with those with normal iPTH-low 25(OH)D levels. CONCLUSIONS: COPD patients with hypovitaminosis D and elevated iPTH have higher risk of moderate exacerbations and hospitalizations than those with hypovitaminosis D and normal iPTH.

Lymph node stromal cell subsets-Emerging specialists for tailored tissue-specific immune responses.

The effective priming of adaptive immune responses depends on the precise dispatching of lymphocytes and antigens into and within lymph nodes (LNs), which are strategically dispersed throughout the body. Over the past decade, a growing body of evidence has advanced our understanding of lymph node stromal cells (LNSCs) from viewing them as mere accessory cells to seeing them as critical cellular players for the modulation of adaptive immune responses. In this review, we summarize current advances on the pivotal roles that LNSCs play in orchestrating adaptive immune responses during homeostasis and infection, and highlight the imprinting of location-specific information by micro-environmental cues into LNSCs, thereby tailoring tissue-specific immune responses.

Geriatric Phenotypes and Their Impact on Oral Health.

Older adults have multiple morbidities that can impact oral, systemic, and psychological health. Although each disorder requires consideration from the provider before treatment, by assessing the common phenotypic presentations of older adults, we can better understand, select, and coordinate treatment modifications that would need to be considered and implemented for dental care.

Impact of Corticosteroid Administration within 7 Days of the Hospitalization for Influenza Pneumonia with Respiratory Failure: A Propensity Score Analysis Using a Nationwide Administrative Database.

Influenza pneumonia, which causes acute respiratory distress syndrome and multiple organ failure, has no established management protocol. Recently, corticosteroid therapy was used to treat coronavirus disease 2019 with respiratory failure; however, its effectiveness as a treatment for influenza pneumonia remains controversial. To investigate the impact of corticosteroid therapy for the early phase of severe influenza pneumonia, we compared influenza pneumonia patients with respiratory failure treated with or without corticosteroids within 7 days after hospital admission using a Japanese nationwide administrative database. The primary endpoint was the mortality rate. The secondary endpoints were duration of intensive-care unit management, invasive mechanical ventilation, and hospital stay. The inverse probability weighting method with estimated propensity scores was used to minimize the data collection bias. We included 3519 patients with influenza pneumonia with respiratory failure. Of these, 875 were treated with corticosteroids. There was no significant difference between the groups regarding 30-day and 90-day mortality, duration of intensive-care unit management, invasive mechanical ventilation, and hospital stay. However, the in-hospital mortality rate was higher in the corticosteroid group. The use of systematic corticosteroid therapy in patients with influenza pneumonia was associated with a higher in-hospital mortality rate.

Physiological Animal Imaging with 68Ga-Citrate.

BACKGROUND: Gallium-68 is an ideal research and hospital-based PET radioisotope. The uptake mechanism of Gallium citrate is a combination of specific and non-specific processes, for example, vasodilatation, increased vascular permeability, plasma transferrin binding and lactoferrin and siderophores. OBJECTIVE: In this study, by applying the 68Ge/68Ga generator product, a simple technique for the synthesis and quality control of 68Ga-citrate was introduced and was followed by preliminary animal studies. METHODS: The synthesis of 68Ga-citrate was performed with a cationic method using the Scintomics automated synthesis system (Scintomics GmbH GRP module 4V). Since the standard procedure for quality control (QC) was not available, the definition of chemical and radiochemical purity of 68Ga-citrate was carried out according to the ICH Q2(R1) guideline. The standard QC tests were analysed with Scintomics 8100 radio-HPLC system equipped with a radioactivity detector. In this study, a New Zealand rabbit weighing 2520 g was used for PET/CT images. RESULTS: 68Ga-citrate synthesis was performed by a cationic method without using organic solvents. The labelling efficiency was found to be >98%. The HPLC method used to assess the radiochemical purity of 68Ga -citrate was validated as rapid, accurate and reproducible enough to apply it to patients safely. The physiological distribution of 68Ga-citrate was investigated in a healthy rabbit. The blood pool, liver, spleen, kidneys and growth plates were the most common sites of 68Ga-citrate involvement.

Coagulopathy of Patients with COVID-19 is Associated with Infectious and Inflammatory Markers.

BACKGROUND: SARS-CoV-2 infection activates coagulation and stimulates innate immune system. Little is known about coagulopathy and response of inflammation and infection in ICU patients with COVID-19. Derangement of coagulation and markers of infection and inflammation induced by SARS-CoV-2 infection, as well as their correlations were elucidated. METHODS: One hundred eight ICU patients with COVID-19 (28 survivors and 80 non-survivors) in Tongji hospital and Wuhan Jinyintan hospital, in Wuhan, China were included. Coagulation parameters, infectious and inflammatory markers were dynamically analysed. The correlation between coagulopathy of patients and infectious and inflammatory markers was verified. RESULTS: SARS-CoV-2-associated coagulopathy occurred in most cases of critical illness. Raised values of d-dimer and FDP were measured in all patients, especially in non-survivors, who had longer PT, APTT, INR, as well as TT, and lower PTA and AT compared to survivors. SIC and DIC mostly occurred in non-survivors. CRP, ESR, serum ferritin, IL-8, and IL-2R increased in all patients, and were much higher in non-survivors who had significantly higher levels of IL-6 and IL-10. D-dimer was positively associated with CRP, serum ferritin (p = 0.02), PCT (p < 0.001), and IL-2R (p = 0.007). SIC scores were positively correlated with CRP (p = 0.006), PCT (p = 0.0007), IL-1ß (p = 0.048), and IL-6 (p = 0.009). DIC scores were positively associated with CRP (p < 0.0001), ESR (p = 0.02), PCT (p < 0.0001), serum ferritin (p < 0.0001), IL-10 (p = 0.02), and IL-2R (p = 0.0005). CONCLUSION: Prothrombotic state, SIC, and DIC are the characteristics of coagulation in ICU patients with COVID-19. CRP, ESR, serum ferritin, IL-8, IL-2R, IL-6, and PCT were stimulated by SARS-CoV-2 infection. CRP, PCT, serum ferritin, and IL-2R indicate the coagulopathy severity of patients with COVID-19.