Increased alternative complement pathway function and improved Survival during Critical Illness

William Bain, Huihua Li, Rick van der Geest, Sara R. Moore, Tolani F. Olonisakin, Brian Ahn, Erin Papke, Kaveh Moghbeli, Rebecca DeSensi, Sarah Rapport, Melissa Saul, Mei Hulver, Zeyu Xiong, Rama K. Mallampalli, Prabir Ray, Alison Morris, Lina Ma, Yohei Doi, Yingze Zhang, Georgios D. KitsiosHrishikesh S. Kulkarni, Bryan J. McVerry, Viviana P. Ferreira, Mehdi Nouraie, Janet S. Lee

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Rationale: Complement is crucial for host defense butmay also drive dysregulated inflammation. There is limited understanding of alternative complement function, which can amplify all complement activity, during critical illness. Objectives: We examined the function and key components of the alternative complement pathway in a series of critically ill patients and in a mouse pneumonia model. Methods: Total classical (CH50) and alternative complement (AH50) function were quantified in serum from 321 prospectively enrolled critically ill patients and compared with clinical outcomes. Alternative pathway (AP) regulatory factors were quantified by ELISA (n = 181) and examined via transcriptomics data from external cohorts. Wild-type, Cfb2/2, and C32/2 mice were infected intratracheally with Klebsiella pneumoniae (KP) and assessed for extrapulmonary dissemination. Measurements and Main Results: AH50 greater than or equal to median, but not CH50 greater than or equal to median, was associated with decreased 30-day mortality (adjusted odds ratio [OR], 0.53 [95% confidence interval (CI), 0.31 0.91]), independent of chronic liver disease. One-year survival was improved in patients with AH50 greater than or equal to median (adjusted hazard ratio = 0.59 [95% CI, 0.41 0.87]). Patients with elevated AH50 had increased levels of AP factors B, H, and properdin, and fewer showed a hyperinflammatory subphenotype (OR, 0.30 [95% CI, 0.18 0.49]). Increased expression of proximal AP genes was associated with improved survival in two external cohorts. AH50 greater than or equal to median was associated with fewer bloodstream infections (OR, 0.67 [95% CI, 0.45 0.98). Conversely, depletion of AP factors, or AH50 less than median, impaired in vitro serum control of KP that was restored by adding healthy serum. Cfb2/2 mice demonstrated increased extrapulmonary dissemination and serum inflammatory markers after intratracheal KP infection compared with wild type. Conclusions: Elevated AP function is associated with improved survival during critical illness, possibly because of enhanced immune capacity.

Original languageEnglish
Pages (from-to)230-240
Number of pages11
JournalAmerican journal of respiratory and critical care medicine
Issue number2
StatePublished - Jul 15 2020


  • Complement
  • Critical illness
  • Host defense
  • Pneumonia
  • Serum


Dive into the research topics of 'Increased alternative complement pathway function and improved Survival during Critical Illness'. Together they form a unique fingerprint.

Cite this