Circulating Bacterial Outer Membrane Vesicle Signatures and Ferroptosis-Related Biomarkers in Sepsis-Associated Acute Lung Injury Among Patients With Extra-Pulmonary Hypervirulent Klebsiella Pneumoniae Infection: A Prospective Observational Translational Cohort Study
试验速览
- 阶段
- 不适用
- 状态
- 尚未招募
- 发起方
- 入组人数
- 120
- 主要终点
- Incidence of New-Onset Sepsis-Associated Acute Lung Injury
研究概览
简要总结
This prospective observational translational cohort study will investigate whether extra-pulmonary infection caused by hypervirulent Klebsiella pneumoniae (hvKP) is associated with an increased risk of sepsis-associated acute lung injury (SALI), compared with infection caused by classical Klebsiella pneumoniae (cKP). The study will further examine whether circulating bacterial outer membrane vesicle (OMV) signals and ferroptosis-related biomarker profiles are associated with subsequent SALI development.
Adults with Sepsis-3 and microbiologically confirmed extra-pulmonary K. pneumoniae infection will be enrolled within 6 hours of sepsis recognition. Patients with acute lung injury at enrollment will be excluded from the primary cohort. Blood samples will be collected at enrollment, 24 hours, and 72 hours. Clinical isolates will undergo molecular characterization to classify infections as hvKP or cKP. The primary outcome will be new-onset SALI within 7 days after enrollment. A nested translational substudy will evaluate the effects of patient-isolate-derived OMVs on human pulmonary microvascular endothelial cells.
The study will not alter antimicrobial therapy, source control, respiratory support, fluid management, or any other aspect of routine clinical care.
详细描述
Sepsis-associated acute lung injury is a major complication of severe extra-pulmonary Gram-negative bacterial infection. Hypervirulent Klebsiella pneumoniae (hvKP) is increasingly recognized as a cause of invasive infection with a high inflammatory burden and a propensity for metastatic spread. Bacterial outer membrane vesicles (OMVs) are biologically active nanoparticles that may transport lipopolysaccharide, virulence-associated molecules, and other inflammatory cargo to distant organs. Experimental evidence suggests that OMV-mediated oxidative stress and ferroptosis-related injury may contribute to pulmonary endothelial dysfunction and acute lung injury; however, the clinical relevance of these mechanisms in patients with extra-pulmonary hvKP sepsis remains unclear.
This prospective multicenter observational translational cohort study will investigate the relationship among molecularly characterized hvKP infection, circulating bacterial OMV-related signals, ferroptosis-related biomarker profiles, and the subsequent development of sepsis-associated acute lung injury. Adults with microbiologically confirmed extra-pulmonary Klebsiella pneumoniae sepsis will be enrolled early after sepsis recognition and followed during the acute phase of illness. Clinical isolates will undergo molecular characterization for prespecified hypervirulence-associated genes and additional strain-level features. Blood specimens collected during routine early follow-up will be processed using standardized procedures for plasma, serum, and peripheral blood mononuclear cell analyses.
The laboratory component will quantify circulating Gram-negative bacterial OMV-related signals in platelet-depleted plasma and evaluate systemic ferroptosis-related biomarker profiles, including lipid peroxidation products, glutathione redox status, iron-related indices, and ferroptosis-associated gene expression. Patient-derived Klebsiella pneumoniae isolates will also be cultured under standardized conditions for OMV isolation and characterization.
A nested translational substudy will compare OMVs derived from representative hvKP and classical Klebsiella pneumoniae isolates. Equal-particle-number OMV preparations will be applied to human pulmonary microvascular endothelial cells to assess lipid peroxidation, ferroptosis-related molecular changes, endothelial barrier integrity, and the in vitro rescue effect of Ferrostatin-1. No investigational intervention will be administered to study participants, and all clinical management will remain at the discretion of the treating physicians.
研究设计
- 研究类型
- Observational
- 观察模型
- Cohort
- 时间视角
- Prospective
入排标准
- 年龄范围
- 18 Years 至 85 Years（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •Age 18-85 years .
- •Clinical suspicion of infection with acute organ dysfunction consistent with suspected sepsis at the time of enrollment, as determined by the treating clinical team.
- •Presumed extra-pulmonary source of infection at enrollment, including but not limited to hepatobiliary, urinary, intra-abdominal, skin and soft-tissue, vascular catheter-related, or primary bloodstream infection.
- •Blood cultures and/or clinically indicated source cultures obtained or ordered as part of routine clinical care.
- •Enrollment and first research blood collection completed within 6 hours after initiation of the clinical sepsis evaluation.
- •No evidence of acute lung injury at the index time point, according to the protocol-defined criteria.
- •Written informed consent obtained from the participant or legally authorized representative, unless an ethics-approved deferred-consent procedure is used.
排除标准
- •Suspected or confirmed primary pulmonary infection at enrollment, including community-acquired pneumonia, hospital-acquired pneumonia, ventilator-associated pneumonia, or aspiration pneumonia.
- •Acute lung injury or acute respiratory distress syndrome present at the index time point.
- •Acute cardiogenic pulmonary edema, acute decompensated heart failure, or another condition that would preclude reliable adjudication of subsequent non-cardiogenic acute lung injury.
- •Recent inhalation injury, near-drowning, major thoracic trauma, or transfusion-related acute lung injury.
- •Previous enrollment in this study.
- •Inability to obtain informed consent from the participant or legally authorized representative when deferred-consent procedures are not permitted by the local ethics committee.
研究组 & 干预措施
Cohort 1 Title: Hypervirulent Klebsiella pneumoniae Infection
Cohort 1 Description:
Participants with subsequently confirmed extra-pulmonary Klebsiella pneumoniae infection whose clinical isolate carries iucA, iroB, peg-344, rmpA, and rmpA2.
Cohort 2 Title: Classical Klebsiella pneumoniae Infection
Cohort 2 Description:
Participants with subsequently confirmed extra-pulmonary Klebsiella pneumoniae infection whose clinical isolate lacks all five prespecified hypervirulence-associated genes: iucA, iroB, peg-344, rmpA, and rmpA2.
Cohort 3 Title: Indeterminate Klebsiella pneumoniae Molecular Phenotype
Cohort 3 Description:
Participants with subsequently confirmed extra-pulmonary Klebsiella pneumoniae infection whose clinical isolate carries one to four of the five prespecified hypervirulence-associated genes. This cohort will be included in exploratory analyses only.
结局指标
主要结局
Incidence of New-Onset Sepsis-Associated Acute Lung Injury
时间窗: From enrollment (T0) through Day 7
New-onset sepsis-associated acute lung injury occurring after enrollment and within 7 days, defined by acute respiratory deterioration, new bilateral pulmonary opacities, hypoxemia, and respiratory failure not fully explained by cardiac failure or fluid overload. Acute lung injury will be adjudicated independently by two physicians blinded to bacterial molecular classification and biomarker results.
次要结局
- Circulating Gram-Negative Bacterial Outer Membrane Vesicle-Related Signal(At enrollment (T0), 24 hours, and 72 hours after enrollment)
- Ferroptosis-Related Biomarker Profile(At enrollment (T0), 24 hours, and 72 hours after enrollment)
- Severity of Respiratory Dysfunction(From enrollment through Day 7)
- Ventilator-Free Days(From enrollment through Day 28)
- All-Cause Mortality(From enrollment through Day 28)
- Lowest PaO₂/FiO₂ Ratio (or SpO₂/FiO₂ Ratio)(From enrollment through Day 7)
- Respiratory Sequential Organ Failure Assessment (SOFA) Score(From enrollment through Day 7)
研究者
Jingyuan,Xu
Associate Professor and Director, Department of Critical Care Medicine
Southeast University, China