Proteomic signatures of perioperative oxygen delivery in skin after major surgery

Objective Maintaining adequate oxygen delivery after major surgery is associated with minimizing organ dysfunction, although the precise molecular mechanisms remain unclear. Background Skin, the largest organ in the body, is vulnerable to reduced oxygen delivery. We hypothesized that the skin proteome, assessed before and after surgery, would reveal molecular differences in patients randomized to receive cardiovascular therapy aimed at maintaining preoperative oxygen delivery (DO2). Methods Abdominal punch skin biopsies were snap frozen or fixed in paraformaldehyde immediately before and 48h after elective esophageal or liver resection. Immediately after surgery, patients were randomized to standard of care or therapy to maintain preoperative DO2. On-line two-dimensional liquid chromatography, followed by ultra-high definition label-free mass spectrometry analysis, and/or immunoblots quantified significant proteomic changes. Selected proteins identified by mass spectrometry were confirmed by immunohistochemistry and immunoblot. In a murine hepatic resection model, confirmation of specific proteomic signatures identified in patients was sought by immunoblotting. Results Paired biopsies were analyzed from 35 patients (mean age:68±9y; 31% female). We identified 2096 proteins, of which 157 were differentially expressed after surgery. Similar results for selected proteins were found using immunohistochemistry (n=6 patients), immunoblots (n=12 patients) and murine abdominal skin obtained after liver resection (n=14). After surgery, 14 proteins distinguished esophagectomy patients with normal (n=10) versus low (n=7) DO2.values. Failure to maintain preoperative DO2 was associated with upregulation of proteins counteracting oxidative stress and. Conclusions Serial skin biopsies afford mechanistic insight into end-organ injury by quantifying proteomic changes associated with impaired oxygen delivery during high-risk surgery. Trial registration ISRCTN76894700 Funding Academy of Medical Sciences/Health Foundation Clinician Scientist Award [GLA]; British Oxygen Company research chair grant in Anesthesia [GLA]; Great Ormond Street Hospital Biomedical Research Centre [EB,WH,KM]; British Heart Foundation:PG/17/40/33028 [MC]; UK NIHR [GLA]; Barts Charity [TJ] Mini-Abstract Skin, one of the largest organs in the body, is vulnerable to reduced oxygen delivery. Proteomic analysis of skin biopsies obtained before and after surgery show distinct metabolic and inflammatory changes related to perioperative oxygen delivery. Mirrored by complementary laboratory data in mice, skin proteomics reveal new insights into perioperative organ dysfunction. ### Competing Interest Statement GLA is an editor for Intensive Care Medicine Experimental and the British Journal of Anaesthesia. GLA has undertaken consultancy work for GlaxoSmithKline. There are no other relationships or activities that could appear to have influenced the submitted work. ### Clinical Trial ISRCTN76894700 ### Funding Statement Funding. Academy of Medical Sciences/Health Foundation Clinician Scientist Award CSF3 [GLA]; British Oxygen Company research chair grant in Anesthesia [GLA]; Great Ormond Street Hospital Biomedical Research Centre [EB,WH,KM]; British Heart Foundation:PG/17/40/33028 [MC]; UK NIHR [GLA]; Barts Charity [TJ] ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: South London Research Ethics Committee Office (09/H0805/58). All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes Data requests to GL Ackland g.ackland{at}qmul.ac.uk