Acyloxyacyl hydrolase promotes pulmonary defense by preventing alveolar macrophage tolerance.

Although alveolar macrophages (AMs) play important roles in preventing and eliminating pulmonary infections, little is known about their regulation in healthy animals. Since exposure to LPS often renders cells hyporesponsive to subsequent LPS exposures ("tolerant"), we tested the hypothesis that LPS produced in the intestine reaches the lungs and stimulates AMs, rendering them tolerant. We found that resting AMs were more likely to be tolerant in mice lacking acyloxyacyl hydrolase (AOAH), the host lipase that degrades and inactivates LPS; isolated Aoah-/- AMs were less responsive to LPS stimulation and less phagocytic than were Aoah+/+ AMs. Upon innate stimulation in the airways, Aoah-/- mice had reduced epithelium- and macrophage-derived chemokine/cytokine production. Aoah-/- mice also developed greater and more prolonged loss of body weight and higher bacterial burdens after pulmonary challenge with Pseudomonas aeruginosa than did wildtype mice. We also found that bloodborne or intrarectally-administered LPS desensitized ("tolerized") AMs while antimicrobial drug treatment that reduced intestinal commensal Gram-negative bacterial abundance largely restored the innate responsiveness of Aoah-/- AMs. Confirming the role of LPS stimulation, the absence of TLR4 prevented Aoah-/- AM tolerance. We conclude that commensal LPSs may stimulate and desensitize (tolerize) alveolar macrophages in a TLR4-dependent manner and compromise pulmonary immunity. By inactivating LPS in the intestine, AOAH promotes antibacterial host defenses in the lung.

Acyloxyacyl hydrolase promotes the resolution of lipopolysaccharide-induced acute lung injury.

Pulmonary infection is the most common risk factor for acute lung injury (ALI). Innate immune responses induced by Microbe-Associated Molecular Pattern (MAMP) molecules are essential for lung defense but can lead to tissue injury. Little is known about how MAMP molecules are degraded in the lung or how MAMP degradation/inactivation helps prevent or ameliorate the harmful inflammation that produces ALI. Acyloxyacyl hydrolase (AOAH) is a host lipase that inactivates Gram-negative bacterial endotoxin (lipopolysaccharide, or LPS). We report here that alveolar macrophages increase AOAH expression upon exposure to LPS and that Aoah+/+ mice recover more rapidly than do Aoah-/- mice from ALI induced by nasally instilled LPS or Klebsiella pneumoniae. Aoah-/- mouse lungs had more prolonged leukocyte infiltration, greater pro- and anti-inflammatory cytokine expression, and longer-lasting alveolar barrier damage. We also describe evidence that the persistently bioactive LPS in Aoah-/- alveoli can stimulate alveolar macrophages directly and epithelial cells indirectly to produce chemoattractants that recruit neutrophils to the lung and may prevent their clearance. Distinct from the prolonged tolerance observed in LPS-exposed Aoah-/- peritoneal macrophages, alveolar macrophages that lacked AOAH maintained or increased their responses to bioactive LPS and sustained inflammation. Inactivation of LPS by AOAH is a previously unappreciated mechanism for promoting resolution of pulmonary inflammation/injury induced by Gram-negative bacterial infection.

Efficacy of immune checkpoint inhibitors in advanced non-small cell lung cancer patients with rare KRAS mutations: a real-world retrospective study.

Background: Kirsten rat sarcoma homolog (KRAS) mutations are one of the key drivers in non-small cell lung cancer (NSCLC) and FDA-approved specific inhibitors of KRAS-G12C mutation are available clinically. However, inhibitors of certain KRAS mutation subtypes remain unavailable, especially rare KRAS mutations including G13C, G13D, and Q61H. In this study, we retrospectively investigated the outcomes of NSCLC patients with rare KRAS-mutation to determine if they may benefit from immune checkpoint inhibitors (ICIs). Methods: Our retrospective study involved 240 advanced NSCLC patients with KRAS mutations, who visited Shanghai Chest Hospital from July 2018 to July 2021. Complete clinical and pathological data were recorded and progression-free survival (PFS) and overall survival (OS) were adopted as primary endpoints. Results: The median follow-up time was 36.5 months (range, 30.8-42.1 months) and the median OS was 9.7 months (range, 7.6-11.8 months). Of the 240 patients evaluated, 130 (54.2%) received chemotherapy and 110 (45.8%) received ICI-based treatment. Among the patients who received chemotherapy, patients with rare KRAS-mutations presented worse survival outcomes (median PFS, 3.4 vs. 4.1 months, P=0.047; median OS, 5.2 vs. 7.1 months, P=0.02) than conventional KRAS-mutant patients. PFS and OS of rare KRAS-mutation patients were prolonged after immunotherapy (median PFS 7.3 vs. 3.4 months, P<0.001; median OS, 13.3 vs. 5.2 months, P<0.001) and had no significant difference compared with conventional KRAS-mutant patients, in part of them whose programmed death-ligand 1 (PD-L1) expression data before immunotherapy were available (n=72), patients with a higher rate of PD-L1 positive tumor cells (≥50%) presented elevated PFS and OS. Conclusions: Despite having potential survival disadvantage compared with other NSCLC patients, rare KRAS-mutant patients (other than G12A, C, D, V) could benefit specifically from ICI-based therapy and survival outcomes are correlated with PD-L1 expression.

PEG2000-PLA-based nanoscale polymeric micelles reduce paclitaxel-related toxicity in beagle dogs.

Nanoplatform-based drug delivery plays an important role in clinical practice. Polymeric micellar (Pm) nanocarriers have been demonstrated to reduce the toxicity of paclitaxel in rats and non-small cell lung cancer (NSCLC) patients. However, the underlying toxicological profile needs to be further illustrated. Here, we used beagles as study subjects and sought to further observe the toxicological profile of polymeric micellar paclitaxel (Pm-Pac) via acute toxicity tests and short-term and long-term toxicity tests. The results from the acute toxicity test indicated that the lethal dose of Pm-Pac in beagles was 20-30 mg/kg, and the acute toxicity-targeted organs were the digestive system and immuno-haematopoietic system. The short-term toxicity test suggested that paclitaxel-induced toxicity (peripheral neuropathy toxicity, haemopoietic toxicity, heart system toxicity, and so on) in beagles can be reduced when paclitaxel is delivered via the Pm delivery system. The long-term toxicity test suggested that Pm-Pac can reduce haemopoietic toxicity in beagles. Collectively, this study provides novel insight into the toxicological profile of Pm-Pac in healthy beagles and provides a potential basis for promising clinical combination strategies in the future.

A highly conserved host lipase deacylates oxidized phospholipids and ameliorates acute lung injury in mice.

Oxidized phospholipids have diverse biological activities, many of which can be pathological, yet how they are inactivated in vivo is not fully understood. Here, we present evidence that a highly conserved host lipase, acyloxyacyl hydrolase (AOAH), can play a significant role in reducing the pro-inflammatory activities of two prominent products of phospholipid oxidation, 1-palmitoyl-2-glutaryl-sn-glycero-3-phosphocholine and 1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphocholine. AOAH removed the sn-2 and sn-1 acyl chains from both lipids and reduced their ability to induce macrophage inflammasome activation and cell death in vitro and acute lung injury in mice. In addition to transforming Gram-negative bacterial lipopolysaccharide from stimulus to inhibitor, its most studied activity, AOAH can inactivate these important danger-associated molecular pattern molecules and reduce tissue inflammation and injury.

TP53 Mutation Status and Biopsy Lesion Type Determine the Immunotherapeutic Stratification in Non-Small-Cell Lung Cancer.

Immunotherapy, a chemotherapy-free process, has emerged as a promising therapeutic strategy to prolong the overall survival (OS) of patients with non-small-cell lung cancer (NSCLC). However, effective stratification factors for immunotherapy remain unclear. The purpose of this study was to discuss the potential stratification factors of NSCLC immunotherapy using immune checkpoint inhibitors (ICIs) by integrating genomic profiling and tumor lesion-type information. In this study, 344 patients with NSCLC, whose clinical and tissue (including metastatic and primary lesions) mutation information was available, were included. The potential gene mutation status for predicting the outcomes of immunotherapy was screened by comparing the difference in mutation frequency between responders and non-responders. Our results indicated that the potential predictors of immunotherapy were significantly different, especially between patients with TP53(+) (including metastatic and primary lesions) and TP53(-) (including metastatic and primary lesions). According to this classification, patients with NSCLC who suggested immunotherapy had a higher OS than those who did not (25 months vs. 7 months, P < 0.0001, hazard ratio = 0.39). Collectively, this study provides a new perspective for screening immunotherapy predictors in NSCLC, suggesting that the TP53 mutation status and source of biopsy tissue should be considered during the development of immunotherapy biomarkers.

A host lipase prevents lipopolysaccharide-induced foam cell formation.

Although microbe-associated molecular pattern (MAMP) molecules can promote cholesterol accumulation in macrophages, the existence of a host-derived MAMP inactivation mechanism that prevents foam cell formation has not been described. Here, we tested the ability of acyloxyacyl hydrolase (AOAH), the host lipase that inactivates gram-negative bacterial lipopolysaccharides (LPSs), to prevent foam cell formation in mice. Following exposure to small intraperitoneal dose(s) of LPSs, Aoah -/- macrophages produced more low-density lipoprotein receptor and less apolipoprotein E and accumulated more cholesterol than did Aoah +/+ macrophages. The Aoah -/- macrophages also maintained several pro-inflammatory features. Using a perivascular collar placement model, we found that Aoah -/- mice developed more carotid artery foam cells than did Aoah +/+ mice after they had been fed a high fat, high cholesterol diet, and received small doses of LPSs. This is the first demonstration that an enzyme that inactivates a stimulatory MAMP in vivo can reduce cholesterol accumulation and inflammation in arterial macrophages.

ctDNA-Profiling-Based UBL Biological Process Mutation Status as a Predictor of Atezolizumab Response Among TP53-Negative NSCLC Patients.

Atezolizumab, an immune checkpoint inhibitor, has been approved for use in clinical practice in non-small cell lung cancer (NSCLC) patients, but potential biomarkers for response stratification still need further screening. In the present study, a total of 399 patients with high-quality ctDNA profiling results were included. The mutation status of ubiquitin-like conjugation (UBL) biological process genes (including ABL1, APC, LRP6, FUBP1, KEAP1, and TOP2A) and clinical information were further integrated. The results suggested that the patients with the clinical characteristics of male or history of smoking had a higher frequency of UBL mutation positivity [UBL (+)]; the patients who were UBL (+) had shorter progression-free survival (PFS) (1.69 vs. 3.22 months, p = 0.0007) and overall survival (8.61 vs. 16.10 months, p < 0.0001) than those patients with UBL mutation negativity [UBL (-)]; and more promising predictive values were shown in the smoker subgroup and ≤ 3 metastasis subgroup. More interestingly, we found the predictor has more performance in TP53-negative cohorts [training in an independent POPLAR and OAK cohorts (n = 200), and validation in an independent MSKCC cohort (n = 127)]. Overall, this study provides a predictor, UBL biological process gene mutation status, not only for identifying NSCLC patients who may respond to atezolizumab therapy but also for screening out the potential NSCLC responders who received other immune checkpoint inhibitors.

LPS inactivation by a host lipase allows lung epithelial cell sensitization for allergic asthma.

Allergic asthma is a chronic inflammatory disease primarily mediated by Th2 immune mechanisms. Numerous studies have suggested that early life exposure to lipopolysaccharide (LPS) is negatively associated with allergic asthma. One proposed mechanism invokes desensitization of lung epithelial cells by LPS. We report here that acyloxyacyl hydrolase (AOAH), a host lipase that degrades and inactivates LPS, renders mice more susceptible to house dust mite (HDM)-induced allergic asthma. Lung epithelial cells from Aoah-/- mice are refractory to HDM stimulation, decreasing dendritic cell activation and Th2 responses. Antibiotic treatment that diminished commensal LPS-producing bacteria normalized Aoah-/- responses to HDM, while giving LPS intrarectally ameliorated asthma. Aoah-/- mouse feces, plasma, and lungs contained more bioactive LPS than did those of Aoah+/+ mice. By inactivating commensal LPS, AOAH thus prevents desensitization of lung epithelial cells. An enzyme that prevents severe lung inflammation/injury in Gram-negative bacterial pneumonia has the seemingly paradoxical effect of predisposing to a Th2-mediated airway disease.