Microbial dynamics, risk factors and outcomes of secondary pneumonia in critically ill patients with COVID-19: A multicenter retrospective cohort study.

BACKGROUND: Secondary pneumonia has a significant clinical impact on critically ill patients with COVID-19. AIM: Considering potential geographic variations, this study explores the clinical implications of secondary pneumonia within East Asian populations. METHODS: This multicenter, retrospective cohort study enrolled critical COVID-19 patients requiring intensive care units (ICUs) admission in Taiwan from December 31, 2020, to June 1, 2022. FINDINGS: Among the 187 critical COVID-19 patients, 80 (42.8%) developed secondary pneumonia. The primary causative pathogens were gram-negative bacilli (GNB) (76.8%). Gram-positive cocci and fungi were mainly observed during the initial two weeks of ICU stay. Notably, the incidence of pulmonary aspergillosis was 9.2% during the first week of ICU stay and all Staphylococcus aureus were susceptible to methicillin. Multi-drug resistant organisms (MDROs) were responsible for 28.3% of the cases, exhibiting significantly longer ICU stays compared to the non-MDRO group (median, 27 vs. 14 days, P < 0.001). In the multivariate analysis, Acute Physiology and Chronic Health Evaluation II (APACHE II) and Sequential Organ Failure Assessment (SOFA) scores were associated with a significantly increased risk of secondary pneumonia. In-hospital mortality was significantly higher in patients with secondary pneumonia than in those without (37.7% vs. 16.7%, P = 0.02) and survival analysis demonstrated gram-negative bacilli-related secondary pneumonia contributed to a worse prognosis. CONCLUSIONS: Secondary pneumonia in critical COVID-19 patients significantly raised in-hospital mortality and extended hospital and ICU stays. Moreover, the presence of GNB notably predicted an unfavorable prognosis.

Immunometabolic features of natural killer cells are associated with infection outcomes in critical illness.

Immunosuppression increases the risk of nosocomial infection in patients with chronic critical illness. This exploratory study aimed to determine the immunometabolic signature associated with nosocomial infection during chronic critical illness. We prospectively recruited patients who were admitted to the respiratory care center and who had received mechanical ventilator support for more than 10 days in the intensive care unit. The study subjects were followed for the occurrence of nosocomial infection until 6 weeks after admission, hospital discharge, or death. The cytokine levels in the plasma samples were measured. Single-cell immunometabolic regulome profiling by mass cytometry, which analyzed 16 metabolic regulators in 21 immune subsets, was performed to identify immunometabolic features associated with the risk of nosocomial infection. During the study period, 37 patients were enrolled, and 16 patients (43.2%) developed nosocomial infection. Unsupervised immunologic clustering using multidimensional scaling and logistic regression analyses revealed that expression of nuclear respiratory factor 1 (NRF1) and carnitine palmitoyltransferase 1a (CPT1a), key regulators of mitochondrial biogenesis and fatty acid transport, respectively, in natural killer (NK) cells was significantly associated with nosocomial infection. Downregulated NRF1 and upregulated CPT1a were found in all subsets of NK cells from patients who developed a nosocomial infection. The risk of nosocomial infection is significantly correlated with the predictive score developed by selecting NK cell-specific features using an elastic net algorithm. Findings were further examined in an independent cohort of COVID-19-infected patients, and the results confirm that COVID-19-related mortality is significantly associated with mitochondria biogenesis and fatty acid oxidation pathways in NK cells. In conclusion, this study uncovers that NK cell-specific immunometabolic features are significantly associated with the occurrence and fatal outcomes of infection in critically ill population, and provides mechanistic insights into NK cell-specific immunity against microbial invasion in critical illness.

Alveolar type II epithelial cell FASN maintains lipid homeostasis in experimental COPD.

Alveolar epithelial type II (AEC2) cells strictly regulate lipid metabolism to maintain surfactant synthesis. Loss of AEC2 cell function and surfactant production are implicated in the pathogenesis of the smoking-related lung disease chronic obstructive pulmonary disease (COPD). Whether smoking alters lipid synthesis in AEC2 cells and whether altering lipid metabolism in AEC2 cells contributes to COPD development are unclear. In this study, high-throughput lipidomic analysis revealed increased lipid biosynthesis in AEC2 cells isolated from mice chronically exposed to cigarette smoke (CS). Mice with a targeted deletion of the de novo lipogenesis enzyme, fatty acid synthase (FASN), in AEC2 cells (FasniΔAEC2) exposed to CS exhibited higher bronchoalveolar lavage fluid (BALF) neutrophils, higher BALF protein, and more severe airspace enlargement. FasniΔAEC2 mice exposed to CS had lower levels of key surfactant phospholipids but higher levels of BALF ether phospholipids, sphingomyelins, and polyunsaturated fatty acid-containing phospholipids, as well as increased BALF surface tension. FasniΔAEC2 mice exposed to CS also had higher levels of protective ferroptosis markers in the lung. These data suggest that AEC2 cell FASN modulates the response of the lung to smoke by regulating the composition of the surfactant phospholipidome.

Using an In-Sample Addition of Medronic Acid for the Analysis of Purine- and Pyrimidine-Related Derivatives and Its Application in the Study of Lung Adenocarcinoma A549 Cell Lines by LC-MS/MS.

Intracellular purine- and pyrimidine-related derivatives are vital molecules for preserving genetic information and are essential for cellular bioenergetics and signal transduction. This study developed a practical liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantifying intracellular purine- and pyrimidine-related derivatives. To solve the distorted peak shape related to di- and triphosphate nucleotides, in-sample addition of medronic acid and ammonium phosphate was performed. Using the BEH-amide column, the results showed that adding 0.5 mM medronic acid to the sample significantly improved the peak shape without causing an obvious ion suppressive effect. Method validation confirmed that the coefficients of determination (R2) values for linearity evaluation were above 0.94 for all analytes. The intraday and interday accuracies ranged from 85.1 to 128.4%, with the precision below 16.6%. The validated method was successfully applied in characterizing the alterations of purine- and pyrimidine-related derivatives in the A549 cell line with perturbed mitochondrial fission or blockade of the electron transport chain. Collectively, this study demonstrates that the strategy of in-sample medronic acid addition is effective in improving the quantification of intracellular purine- and pyrimidine-related derivatives. We believe that our proposed platform can facilitate the development of novel drugs targeting purine and pyrimidine metabolism in the future.

HLJ1 amplifies endotoxin-induced sepsis severity by promoting IL-12 heterodimerization in macrophages.

Heat shock protein (HSP) 40 has emerged as a key factor in both innate and adaptive immunity, whereas the role of HLJ1, a molecular chaperone in HSP40 family, in modulating endotoxin-induced sepsis severity is still unclear. During lipopolysaccharide (LPS)-induced endotoxic shock, HLJ1 knockout mice shows reduced organ injury and IFN-γ (interferon-γ)-dependent mortality. Using single-cell RNA sequencing, we characterize mouse liver nonparenchymal cell populations under LPS stimulation, and show that HLJ1 deletion affected IFN-γ-related gene signatures in distinct immune cell clusters. In CLP models, HLJ1 deletion reduces IFN-γ expression and sepsis mortality rate when mice are treated with antibiotics. HLJ1 deficiency also leads to reduced serum levels of IL-12 in LPS-treated mice, contributing to dampened production of IFN-γ in natural killer cells but not CD4+ or CD8+ T cells, and subsequently to improved survival rate. Adoptive transfer of HLJ1-deleted macrophages into LPS-treated mice results in reduced IL-12 and IFN-γ levels and protects the mice from IFN-γ-dependent mortality. In the context of molecular mechanisms, HLJ1 is an LPS-inducible protein in macrophages and converts misfolded IL-12p35 homodimers to monomers, which maintains bioactive IL-12p70 heterodimerization and secretion. This study suggests HLJ1 causes IFN-γ-dependent septic lethality by promoting IL-12 heterodimerization, and targeting HLJ1 has therapeutic potential in inflammatory diseases involving activated IL-12/IFN-γ axis.

Prognostic significance of dynamin-related protein 1 expression in advanced lung adenocarcinoma.

BACKGROUND: Dynamin-related protein 1 (DRP1) is a key regulator of mitochondrial fission and is activated by phosphorylation at serine 616. We previously demonstrated that DRP1 activation is regulated by epidermal growth factor receptor (EGFR) signaling and multiple kinases in lung adenocarcinoma, and is significantly associated with an increased risk of postoperative recurrence in early stage lung adenocarcinoma. However, it is unclear whether DRP1 activation is associated with worse prognosis in patients with advanced lung adenocarcinoma. This study is aimed to examine whether P(S616)-DRP1 expression is significantly related to the survival of patients with advanced lung adenocarcinoma. MATERIALS AND METHODS: Biopsy samples were obtained from patients with stage IV lung adenocarcinoma. The activation status of DRP1 in cancer cells was quantified based on the immunohistochemical stain of phosphorylated DRP1 at serine 616 [P(S616)-DRP1]. Results of EGFR, ALK, ROS1, and KRAS mutations were retrieved from the medical records. The staining intensity and the histological scores (H-scores) of P(S616)-DRP1 were analyzed for association with progression-free survival (PFS) under first-line tyrosine-kinase inhibitors (TKIs) and with overall survival (OS). RESULTS: Overall, 123 patients with stage IV lung adenocarcinoma constituted the study population, and 90 (73.2%) patients received TKIs as the first-line treatments. The median P(S616)-DRP1H-score was used to dichotomize the study population into the high (n = 61) and low (n = 62) DRP1 activation groups. DRP1 was significantly less phosphorylated in lung adenocarcinoma with EGFR, ALK, ROS1, and KRAS mutations. Importantly, in patients who received first-line TKIs, DRP1 phosphorylation was not significantly correlated with PFS and OS. Multivariate Cox proportional hazard models showed that high DRP1 activation in cancer cells was not significantly associated with worse OS in the study population (adjusted hazard ratio: 1.402, 95% confidence interval: 0.865-2.271, p = 0.170). Similar results were obtained in the analysis based on the intensities of P(S616)-DRP1 in cancer cells. CONCLUSIONS: Our data demonstrate that DRP1 phosphorylation is not related to the prognosis of patients with advanced lung adenocarcinoma.

Multi-kinase framework promotes proliferation and invasion of lung adenocarcinoma through activation of dynamin-related protein 1.

Recent studies revealed the role of dynamin-related protein 1 (DRP1), encoded by the DNM1L gene, in regulating the growth of cancer cells of various origins. However, the regulation, function, and clinical significance of DRP1 remain undetermined in lung adenocarcinoma. Our study shows that the expression and activation of DRP1 are significantly correlated with proliferation and disease extent, as well as an increased risk of postoperative recurrence in stage I to stage IIIA lung adenocarcinoma. Loss of DRP1 in lung adenocarcinoma cell lines leads to an altered mitochondrial morphology, fewer copies of mitochondrial DNA, decreased respiratory complexes, and impaired oxidative phosphorylation. Additionally, the proliferation and invasion are both suppressed in DRP1-depleted lung adenocarcinoma cell lines. Our data further revealed that DRP1 activation through serine 616 phosphorylation is regulated by ERK/AKT and CDK2 in lung adenocarcinoma cell lines. Collectively, we propose the multikinase framework in activating DRP1 in lung adenocarcinoma to promote the malignant properties. Biomarkers related to mitochondrial reprogramming, such as DRP1, can be used to evaluate the risk of postoperative recurrence in early-stage lung adenocarcinoma.

Persistent severe acute respiratory distress syndrome for the prognostic enrichment of trials.

BACKGROUND: Acute respiratory distress syndrome (ARDS) is heterogeneous. As an indication of the heterogeneity of ARDS, there are patients whose syndrome improves rapidly (i.e., within 24 hours), others whose hypoxemia improves gradually and still others whose severe hypoxemia persists for several days. The latter group of patients with persistent severe ARDS poses challenges to clinicians. We attempted to assess the baseline characteristics and outcomes of persistent severe ARDS and to identify which variables are useful to predict it. METHODS: A secondary analysis of patient-level data from the ALTA, EDEN and SAILS ARDSNet clinical trials was conducted. We defined persistent severe ARDS as a partial pressure of arterial oxygen to fraction of inspired oxygen ratio (PaO2:FiO2) of equal to or less than 100 mmHg on the second study day following enrollment. Regularized logistic regression with an L1 penalty [Least Absolute Shrinkage and Selection Operator (LASSO)] techniques were used to identify predictive variables of persistent severe ARDS. RESULTS: Of the 1531 individuals with ARDS alive on the second study day after enrollment, 232 (15%) had persistent severe ARDS. Of the latter, 100 (43%) individuals had mild or moderate hypoxemia at baseline. Usage of vasopressors was greater [144/232 (62%) versus 623/1299 (48%); p<0.001] and baseline severity of illness was higher in patients with versus without persistent severe ARDS. Mortality at 60 days [95/232 (41%) versus 233/1299 (18%); p<0.001] was higher, and ventilator-free (p<0.001), intensive care unit-free [0 (0-14) versus 19 (7-23); p<0.001] and non-pulmonary organ failure-free [3 (0-21) versus 20 (1-26); p<0.001] days were fewer in patients with versus without persistent severe ARDS. PaO2:FiO2, FiO2, hepatic failure and positive end-expiratory pressure at enrollment were useful predictive variables. CONCLUSIONS: Patients with persistent severe ARDS have distinct baseline characteristics and poor prognosis. Identifying such patients at enrollment may be useful for the prognostic enrichment of trials.

Mitophagy-dependent macrophage reprogramming protects against kidney fibrosis.

Mitophagy, by maintaining mitochondrial quality control, plays a key role in maintaining kidney function and is impaired in pathologic states. Macrophages are well known for their pathogenic role in kidney fibrosis. Here, we report that PINK1/Parkin-mediated mitophagy in macrophages is compromised in experimental and human kidney fibrosis. We demonstrate downregulation of mitophagy regulators mitofusin-2 (MFN2) and Parkin downstream of PINK1 in kidney fibrosis. Loss of either Pink1 or Prkn promoted renal extracellular matrix accumulation and frequency of profibrotic/M2 macrophages. Pink1-/- or Prkn-/- BM-derived macrophages (BMDMs) showed enhanced expression of rictor. Mitochondria from TGF-ß1-treated Pink1-/- BMDMs exhibited increased superoxide levels, along with reduced respiration and ATP production. In addition, mitophagy in macrophages involves PINK1-mediated phosphorylation of downstream MFN2, MFN2-facilitated recruitment of Parkin to damaged mitochondria, and macrophage-specific deletion of Mfn2 aggravates kidney fibrosis. Moreover, mitophagy regulators were downregulated in human CKD kidney and TGF-ß1-treated human renal macrophages, whereas Mdivi1 treatment suppressed mitophagy mediators and promoted fibrotic response. Taken together, our study is the first to our knowledge to demonstrate that macrophage mitophagy plays a protective role against kidney fibrosis via regulating the PINK1/MFN2/Parkin-mediated pathway.

Mitofusins regulate lipid metabolism to mediate the development of lung fibrosis.

Accumulating evidence illustrates a fundamental role for mitochondria in lung alveolar type 2 epithelial cell (AEC2) dysfunction in the pathogenesis of idiopathic pulmonary fibrosis. However, the role of mitochondrial fusion in AEC2 function and lung fibrosis development remains unknown. Here we report that the absence of the mitochondrial fusion proteins mitofusin1 (MFN1) and mitofusin2 (MFN2) in murine AEC2 cells leads to morbidity and mortality associated with spontaneous lung fibrosis. We uncover a crucial role for MFN1 and MFN2 in the production of surfactant lipids with MFN1 and MFN2 regulating the synthesis of phospholipids and cholesterol in AEC2 cells. Loss of MFN1, MFN2 or inhibiting lipid synthesis via fatty acid synthase deficiency in AEC2 cells exacerbates bleomycin-induced lung fibrosis. We propose a tenet that mitochondrial fusion and lipid metabolism are tightly linked to regulate AEC2 cell injury and subsequent fibrotic remodeling in the lung.

Increased Plasma Acetylcarnitine in Sepsis Is Associated With Multiple Organ Dysfunction and Mortality: A Multicenter Cohort Study.

OBJECTIVES: Recent metabolomic studies of sepsis showed that increased circulatory acylcarnitines were associated with worse survival. However, it is unknown whether plasma carnitine and acylcarnitines can reflect the severity of sepsis, and the role of specific acylcarnitines in prognostic assessment need further confirmation. This study aimed to clarify these questions. DESIGN: Prospective multicenter cohort studies with derivation and validation cohort design. SETTING: ICUs at two medical centers and three regional hospitals in Taiwan. PATIENTS: Patients with sepsis and acute organ dysfunction were enrolled. Recruitment of the derivation (n = 90) and validation cohorts (n = 120) occurred from October 2010 through March 2012 and January 2013 through November 2014, respectively. INTERVENTIONS: Plasma samples were collected immediately after admission, and the levels of carnitine and acylcarnitines were measured by ultra-high performance liquid chromatography-mass spectrometry. MEASUREMENTS AND MAIN RESULTS: In the derivation cohort, increased plasma levels of short- and medium-chain acylcarnitines were significantly associated with hepatobiliary dysfunction, renal dysfunction, thrombocytopenia, and hyperlactatemia. However, acetylcarnitine is the only acylcarnitine significantly correlating with various plasma cytokine concentrations and also associated with blood culture positivity and 28-day mortality risk. The association between plasma acetylcarnitine and multiple organ dysfunction severity, blood culture positivity, and 28-day mortality, was confirmed in the validation cohort. Patients with high plasma acetylcarnitine (≥ 6,000 ng/mL) had significantly increased 28-day mortality compared with those with plasma acetylcarnitine less than 6,000 ng/mL (52.6% vs 13.9%; hazard ratio, 5.293; 95% CI, 2.340-11.975; p < 0.001 by Cox proportional hazard model). CONCLUSIONS: We confirm that plasma acetylcarnitine can reflect the severity of organ dysfunction, inflammation, and infection in sepsis and can serve as a prognostic biomarker for mortality prediction.

RIPK3 promotes kidney fibrosis via AKT-dependent ATP citrate lyase.

Renal fibrosis is a common pathogenic response to injury in chronic kidney disease (CKD). The receptor-interacting protein kinase-3 (RIPK3), a regulator of necroptosis, has been implicated in disease pathogenesis. In mice subjected to unilateral ureteral obstruction-induced (UUO-induced) or adenine diet-induced (AD-induced) renal fibrosis, models of progressive kidney fibrosis, we demonstrate increased kidney expression of RIPK3. Mice genetically deficient in RIPK3 displayed decreased kidney fibrosis and improved kidney function relative to WT mice when challenged with UUO or AD. In contrast, mice genetically deficient in mixed-lineage kinase domain-like protein (MLKL), a downstream RIPK3 target, were not protected from UUO-induced kidney fibrosis. We demonstrate a pathway by which RIPK3 promotes fibrogenesis through the AKT-dependent activation of ATP citrate lyase (ACL). Genetic or chemical inhibition of RIPK3 suppressed the phosphorylation of AKT and ACL in response to TGF-ß1 in fibroblasts. Inhibition of AKT or ACL suppressed TGF-ß1-dependent extracellular matrix production and myofibroblast differentiation in fibroblasts. Pharmacological inhibition of ACL suppressed UUO-induced kidney fibrosis. RIPK3 expression was highly regulated in human CKD kidney. In conclusion, we identify a pathway by which RIPK3 promotes kidney fibrosis independently of MLKL-dependent necroptosis as a promising therapeutic target in CKD.

Significant Clinical Factors Associated with Long-term Mortality in Critical Cancer Patients Requiring Prolonged Mechanical Ventilation.

Studies about prognostic assessment in cancer patients requiring prolonged mechanical ventilation (PMV) for post-intensive care are scarce. We retrospectively enrolled 112 cancer patients requiring PMV support who were admitted to the respiratory care center (RCC), a specialized post-intensive care weaning facility, from November 2009 through September 2013. The weaning success rate was 44.6%, and mortality rates at hospital discharge and after 1 year were 43.8% and 76.9%, respectively. Multivariate logistic regression showed that weaning failure, in addition to underlying cancer status, was significantly associated with an increased 1-year mortality (odds ratio, 6.269; 95% confidence interval, 1.800-21.834; P = 0.004). Patients who had controlled non-hematologic cancers and successful weaning had the longest median survival, while those with other cancers who failed weaning had the worst. Patients with low maximal inspiratory pressure, anemia, and poor oxygenation at RCC admission had an increased risk of weaning failure. In conclusion, cancer status and weaning outcome were the most important determinants associated with long-term mortality in cancer patients requiring PMV. We suggest palliative care for those patients with clinical features associated with worse outcomes. It is unknown whether survival in this specific patient population could be improved by modifying the risk of weaning failure.

NOX4-dependent fatty acid oxidation promotes NLRP3 inflammasome activation in macrophages.

Altered metabolism has been implicated in the pathogenesis of inflammatory diseases. NADPH oxidase 4 (NOX4), a source of cellular superoxide anions, has multiple biological functions that may be of importance in inflammation and in the pathogenesis of human metabolic diseases, including diabetes. However, the mechanisms by which NOX4-dependent metabolic regulation affect the innate immune response remain unclear. Here we show that deficiency of NOX4 resulted in reduced expression of carnitine palmitoyltransferase 1A (CPT1A), which is a key mitochondrial enzyme in the fatty acid oxidation (FAO) pathway. The reduced FAO resulted in less activation of the nucleotide-binding domain, leucine-rich-repeat-containing receptor (NLR), pyrin-domain-containing 3 (NLRP3) inflammasome in human and mouse macrophages. In contrast, NOX4 deficiency did not inhibit the activation of the NLR family, CARD-domain-containing 4 (NLRC4), the NLRP1 or the absent in melanoma 2 (AIM2) inflammasomes. We also found that inhibition of FAO by etomoxir treatment suppressed NLRP3 inflammasome activation. Furthermore, Nox4-deficient mice showed substantial reduction in caspase-1 activation and in interleukin (IL)-1ß and IL-18 production, and there was improved survival in a mouse model of NLRP3-mediated Streptococcus pneumoniae infection. The pharmacologic inhibition of NOX4 by either GKT137831, which is currently in phase 2 clinical trials, or VAS-2870 attenuated NLRP3 inflammasome activation. Our results suggest that NOX4-mediated FAO promotes NLRP3 inflammasome activation.

Diffuse alveolar damage in a patient with rheumatoid arthritis under prolonged leflunomide treatment: A Case Report and Literature Review.

Patients with rheumatoid arthritis (RA) often have pulmonary involvement, and interstitial lung disease (ILD) is the primary manifestation, in which diffuse alveolar damage (DAD) is a rare histopathologic pattern. Leflunomide (LEF) is a frequently prescribed disease-modifying antirheumatic drug for treating RA. LEF-related ILD in the form of DAD has been reported in patients with RA, with the duration of LEF treatment before symptom onset ranging from 6 to 1204 days.We present a case of elderly woman with RA under prolonged LEF treatment for >9 years (3291 days), who had acute respiratory failure with the initial presentation of exertional dyspnea, fever, chills, and productive cough for 2 days. The histopathologic result of surgical lung biopsy was compatible with DAD. She was diagnosed as having LEF-related ILD, based on correlated clinical history, compatible histopathologic examination and excluding possible infection after extensive survey.Although the causative role of LEF cannot be confirmed, this case still hints that LEF-related DAD may occur even if LEF has been prescribed for a prolonged period.

Clinical Relevance of Liver Kinase B1(LKB1) Protein and Gene Expression in Breast Cancer.

Liver kinase B1 (LKB1) is a tumor suppressor, and its loss might lead to activation of the mammalian target of rapamycin (mTOR) and tumorigenesis. This study aimed to determine the clinical relevance of LKB1 gene and protein expression in breast cancer patients. LKB1 protein expression was evaluated using immunohistochemistry in tumors from early breast cancer patients in two Taiwanese medical centers. Data on LKB1 gene expression were obtained from the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) data set. The correlations between LKB1 expression, clinicopathologic factors, and patient outcome were analyzed. LKB1 expression was significantly associated with estrogen receptor (ER) expression in 2 of the 4 cohorts, but not with other clinicopathologic factors. LKB1 expression was not a predictor for relapse-free survival, overall survival (OS), or breast cancer-specific survival. In a subgroup analysis of the two Taiwanese cohorts, high LKB1 protein expression was predictive of high OS in human epidermal growth factor receptor 2 (HER2)-positive breast cancer patients (P = 0.013). Our study results indicate that LKB1 expression is not prognostic in the whole population of breast cancer patients, but it is a potential predictor of OS in the subset of HER2-positive patients.

Severe lymphopenia is associated with elevated plasma interleukin-15 levels and increased mortality during severe sepsis.

Sepsis-related mortality has been found increased in RAG-1 knockout mice. However, in patients admitted to medical intensive care units, it is unknown whether severe lymphocyte depletion at admission is associated with increased interleukin (IL)-7 and IL-15 levels in circulation, and increased mortality. We prospectively enrolled 92 patients who were admitted to medical intensive care units for severe sepsis or septic shock. At admission, 24 patients (26.1%) had severe lymphopenia, defined as lymphocyte counts of less than 0.5 × 10(3)/µL. Severe lymphopenia was associated with significantly higher plasma levels of tumor necrosis factor α, IL-6, IL-8, and IL-10 and was also independently associated with 28-day mortality (adjusted hazard ratio, 3.532; 95% confidence interval, 1.482-8.416; P = 0.004). The levels of plasma IL-15, but not IL-7, were increased modestly in patients with severe lymphopenia compared with those without (median, 12.2 vs. 6.4 pg/mL; P = 0.005). The elevated plasma IL-15 levels were contrarily associated with significantly decreased B-cell lymphoma 2 mRNA expression in peripheral blood mononuclear cells. In conclusion, severe lymphopenia was associated with increased mortality in patients with severe sepsis. We found that patients with sepsis with severe lymphopenia had down-regulated B-cell lymphoma 2 mRNA expression in peripheral blood mononuclear cells, despite increased plasma IL-15 concentrations. Whether IL-7 and IL-15 are insufficient in patients with severe lymphopenia during severe sepsis warrants further investigations.

PlGF mediates neutrophil elastase-induced airway epithelial cell apoptosis and emphysema.

BACKGROUND: Chronic pulmonary obstructive disease (COPD) has become the fourth leading cause of death worldwide. Cigarette smoking induces neutrophil elastase (NE) and contributes to COPD, but the detailed mechanisms involved are not fully established. In an animal model of pulmonary emphysema, there are increased expressions of placenta growth factor (PlGF) and lung epithelial (LE) cell apoptosis. This study hypothesized that excessive NE may up-regulate PlGF and that PlGF-induced LE apoptosis mediates the pathogenesis of pulmonary emphysema. METHODS: Human bronchial epithelial cells, BEAS-2B, and primary mouse type II alveolar epithelial cells were treated with NE. The PlGF promoter activity was examined by luciferase activity assay, while PlGF expression and secretion were evaluated by RT-PCR, Western blotting, and ELISA. Both cell lines were treated with PlGF to evaluate its effects and the downstream signaling pathways leading to LE cell apoptosis. PlGF knockout and wild-type mice were instilled with NE to determine the roles of PlGF and its downstream molecules in NE-promoted mice pulmonary apoptosis and emphysema phenotype. RESULTS: The transcriptional factor, early growth response gene-1, was involved in the NE-promoted PlGF promoter activity, and the expression and secretion of PlGF mRNA and protein in LE cells. PlGF-induced LE cell apoptosis and NE-induced mice pulmonary apoptosis and emphysema were mediated by the downstream c-Jun N-terminal kinase (JNK) and protein kinase C (PKC)δ signaling pathways. CONCLUSION: The NE-PlGF-JNK/PKCδ pathway contributes to the pathogenesis of LE cell apoptosis and emphysema. PlGF and its downstream signaling molecules may be potential therapeutic targets for COPD.

Elastase induces lung epithelial cell autophagy through placental growth factor: a new insight of emphysema pathogenesis.

Chronic obstructive pulmonary disease (COPD) is a devastating disease, which is associated with increasing mortality and morbidity. Therefore, there is a need to clearly define the COPD pathogenic mechanism and to explore effective therapies. Previous studies indicated that cigarette smoke (CS) induces autophagy and apoptosis in lung epithelial (LE) cells. Excessive ELANE/HNE (elastase, neutrophil elastase), a factor involved in protease-antiprotease imbalance and the pathogenesis of COPD, causes LE cell apoptosis and upregulates the expression of several stimulus-responsive genes. However, whether or not elastase induces autophagy in LE cell remains unknown. The level of PGF (placental growth factor) is higher in COPD patients than non-COPD controls. We hypothesize that elastase induces PGF expression and causes autophagy in LE cells. In this study, we demonstrated that porcine pancreatic elastase (PPE) induced PGF expression and secretion in LE cells in vitro and in vivo. The activation of MAPK8/JNK1 (mitogen-activated protein kinase 8) and MAPK14/p38alpha MAPK signaling pathways was involved in the PGF mediated regulation of the TSC (tuberous sclerosis complex) pathway and autophagy in LE cells. Notably, PGF-induced MAPK8 and MAPK14 signaling pathways mediated the inactivation of MTOR (mechanistic target of rapamycin), the upregulation of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3 ß) and the increase of autophagosome formation in mice. Furthermore, the PPE-induced autophagy promotes further apoptosis in vitro and in vivo. In summary, elastase-induced autophagy promotes LE cell apoptosis and pulmonary emphysema through the upregulation of PGF. PGF and its downstream MAPK8 and MAPK14 signaling pathways are potential therapeutic targets for the treatment of emphysema and COPD.