Imbalance of pro- and anti-inflammatory cytokine responses in elderly patients after coronary artery bypass grafting

A Systematic Review and Meta-Analysis Examining the Impact of Age on Perioperative Inflammatory Biomarkers

BACKGROUND

Dysregulation of immune responses to surgical stress in older patients and those with frailty may manifest as differences in inflammatory biomarkers. We conducted a systematic review and meta-analysis to examine differences in perioperative inflammatory biomarkers between older and younger patients, and between patients with and without frailty.

METHODS

MEDLINE, Embase, Cochrane, and CINAHL databases were searched (Inception to June 23, 2020). Observational or experimental studies reporting the perioperative level or activity of biomarkers in surgical patients stratified by age or frailty status were included. The primary outcome was inflammatory biomarkers (grouped by window of ascertainment: pre-op; post-op: <12 hours, 12-24 hours, 1-3 days, 3 days to 1 week, and >1 week). Quality assessment was conducted using the Newcastle-Ottawa Scale. Inverse-variance, random-effects meta-analysis was conducted.

RESULTS

Forty-five studies (4263 patients) were included in the review, of which 36 were pooled for meta-analysis (28 noncardiac and 8 cardiac studies). Two studies investigated frailty as the exposure, while the remaining investigated age. In noncardiac studies, older patients had higher preoperative levels of interleukin (IL)-6 and C-reactive protein (CRP), lower preoperative levels of lymphocytes, and higher postoperative levels of IL-6 (<12 hours) and CRP (12-24 hours) than younger patients. In cardiac studies, older patients had higher preoperative levels of IL-6 and CRP and higher postoperative levels of IL-6 (<12 hours and >1 week).

CONCLUSIONS

Our findings demonstrate a paucity of frailty-specific studies; however, the presence of age-associated differences in the perioperative inflammatory response is consistent with age-associated states of chronic systemic inflammation and immunosenescence. Additional studies assessing frailty-specific changes in the systemic biologic response to surgery may inform the development of targeted interventions.

Attenuated recovery of contractile function in aging hearts following global ischemia/reperfusion: Role of extracellular HSP27 and TLR4

BACKGROUND

While cardiac functional recovery is attenuated in the elderly following cardiac surgery with obligatory global myocardial ischemia/reperfusion (I/R), the underlying mechanism remains incompletely understood. We observed previously that human and mouse myocardium releases heat shock protein (HSP) 27 during global I/R. Extracellular HSP27 induces myocardial inflammatory response and plays a role in post-ischemic cardiac dysfunction in adult mouse hearts.

OBJECTIVE

This study was to determine the role of extracellular HSP27 and Toll-like receptor 4 (TLR4) in the attenuated functional recovery in aging mouse hearts following global I/R.

METHODS AND RESULTS

Hearts isolated from aging (18-24 months) and adult (4-6 months) mice were subjected to ex vivo global I/R. Augmented release of HSP27 in aging hearts is associated with greater production of cytokines (TNF-α and IL-1β) and worse functional recovery. Anti-HSP27 suppressed the inflammatory response and markedly improved functional recovery in aging hearts. Perfusion of recombinant HSP27 to aging hearts resulted in greater cytokine production and more severe contractile depression in comparison to adult hearts. TLR4 deficiency abolished cytokine production and functional injury in aging hearts exposed to recombinant HSP27. Interestingly, aging hearts had higher TLR4 protein levels and displayed enhanced TLR4-mediated NF-κB activation following HSP27 stimulation or I/R.

CONCLUSION

Extracellular HSP27 and TLR4 jointly enhance the inflammatory response and hamper functional recovery following I/R in aging hearts. The enhanced inflammatory response to global I/R and attenuated post-ischemic functional recovery in aging hearts is due, at least in part, to augmented myocardial release of HSP27 and elevated myocardial TLR4 levels.

Interleukin 6 production during cardiac surgery correlates with increasing age

BACKGROUND

Cardiac surgery produces a proinflammatory response characterized by cytokine production. Proinflammatory cytokines such as interleukin 6 (IL-6) may contribute to morbidity and mortality after cardiopulmonary bypass (CPB). Elderly patients undergoing CPB are at increased risk of morbidity and mortality. We hypothesized that patients aged >70 y produce more IL-6 during CPB.

METHODS

Twenty-three patients (ages 23-80) undergoing cardiac surgery had blood sampled from the ascending aorta and coronary sinus on initial cannulation for bypass, at 30 min of aortic cross-clamp time, on release of the aortic cross-clamp, and at 20 min after reperfusion. Group 1 patients (n = 8) were aged <60 y, group 2 patients (n = 7) were aged between 60 and 70 y, and group 3 patients (n = 8) were aged >70 y. Plasma levels of tumor necrosis factor-alpha, IL-1, and IL-6 were analyzed.

RESULTS

The three groups did not differ with respect to preoperative ejection fraction, New York Heart Association classification, mean aortic cross-clamp time, or mean CPB time. IL-6 levels rose throughout myocardial ischemia and reperfusion in all three age groups. The increase in IL-6 during ischemia and reperfusion in the age group >70 was greater than the increase in younger patients. IL-6 was similar in the coronary sinus and the ascending aorta.

CONCLUSIONS

These data suggest that patients aged >70 y undergoing cardiac operations generate more IL-6 during CPB. The increased circulating IL-6 in elderly patients may incite a proinflammatory state that could subsequently underlie the associated higher mortality and morbidity of these procedures in elderly patients.

Is Minimally Invasive Spine Surgery Also Minimally Pro-Inflammatory? Muscular Markers, Inflammatory Parameters and Cytokines to Quantify the Operative Invasiveness Assessment in Spine Fusion

Over the last decades, minimally invasive surgery (MIS) techniques entered in the surgical routine due to their major advantage in reducing the unnecessary exposure of tissue and, thus, the trauma. Even in the context of orthopedics and spine surgery these practices have been widely developed and applied. Besides the clinical outcome of the patients, few studies have quantitatively assessed the traumatic and inflammatory effects of a specific surgical technique. Indeed, currently, a universally accepted biological outcome measure, such as a panel of biochemical markers, to define the success of MIS approach is still lacking. We reviewed the literature to collect the published data regarding the quantitative analysis of trauma induced by either conventional or minimally invasive surgery with the aim of highlighting evidence useful to guide future studies. Previous publications show some evidence in support of the hypothesis that MIS approaches are less traumatic, and possibly less pro-inflammatory, than conventional ones. Creatin kinase (as a marker of muscular damage) and C-reactive protein (as a marker of systemic inflammation) seem to reproducibly follow different trends in minimally invasive surgery compared to conventional procedures. Moreover, cytokines, such as interleukin (IL)-6 and IL-10 are also promising markers in this context.

Postoperative suppression of inflammatory cytokines after distal gastrectomy in elderly patients

PURPOSE

Surgical procedures are being performed on elderly people with increasing frequency, but accordingly, postoperative complications and mortality rates are higher than for younger patients. We conducted this study to establish if cytokine responses after distal gastrectomy in elderly patients differ from those in younger patients.

METHODS

Twenty-one patients undergoing distal gastrectomy were divided into two groups based on age: the elderly group consisted of 10 patients aged >/=75 years, and the younger group consisted of 11 patients aged <65 years. Blood samples were collected from the patients preoperatively, and then on postoperative days (PODs) 1, 3, and 7, for analysis of interleukin (IL)-6, IL-8, IL-10, soluble tumor necrosis factor receptors (sTNF-R), and IL-1 receptor antagonist (IL-1ra); and also to measure TNF-alpha and IL-1beta after incubation with Escherichia coli lipopolysaccharide.

RESULTS

The IL-6 concentration and TNF-alpha on POD 1 were both significantly lower in the elderly group than in the younger group (P = 0.0058 and P = 0.022, respectively).

CONCLUSION

Cytokine profiles after distal gastrectomy in elderly patients differ from those in younger patients, with lower pro-inflammatory and inflammatory cytokine responses evident in the elderly.

The quantitative analysis of tissue injury markers after mini-open lumbar fusion

STUDY DESIGN

A prospective and comparative analysis of tissue injury after mini-open lumbar fusion and conventional technique.

OBJECTIVE

To evaluate the tissue injury quantitatively after mini-open lumbar fusion.

SUMMARY OF BACKGROUND DATA

The advantages of minimally invasive techniques demonstrated by clinical reports have been a smaller scar, lesser pain, and rapid rehabilitation. It has not been established, however, that the minimally invasive technique has less tissue injury and less systemic response than the conventional spine surgery.

METHODS

Twenty patients who had undergone posterior decompression and the fusion of the L4-L5 segment for spinal stenosis were studied prospectively. Ten patients that had the conventional posterior decompression and posterior lumbar interbody fusion (PLIF) at L4-L5 were enrolled in a control group. The remaining 10 patients who underwent MISS techniques (paramedian mini-open approach using a tubular retractor) were enrolled in a study group. The serum enzymes representing skeletal muscle injury (creatinine kinase and aldolase), pro-inflammatory cytokines (IL-6, IL-8), and anti-inflammatory cytokines (IL-10, IL-1 receptor antagonist) were analyzed with ELISA techniques. They were checked on the day before operation and 1, 3, 7, and 14 days after operation.

RESULTS

Serum creatinine kinase and most of the inflammatory cytokines were significantly high in the control group on postoperative days 1 and 3 and returned to the normal level on postoperative day 7. Serum aldolase was significantly high on postoperative day 1, and IL-8 remained elevated until postoperative day 7 in the control group.

CONCLUSION

Mini-open lumbar fusion may significantly contribute to the reduction of muscle injury and systemic inflammatory reactions during the acute postoperative period. This study suggests that mini-open lumbar fusion may also play an important role in preventing medical morbidity after spinal surgery.

Acute changes in circulating hormones in older patients with impaired ventricular function undergoing on-pump coronary artery bypass grafting

OBJECTIVES

Coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB) causes an acute stress response characterized by changes in the levels of several hormones, which might play a role in the high complication rate experienced by older patients after CABG. Thus, the aim of the study was to investigate changes in the circulating levels of anabolic and catabolic hormones in old people undergoing CABG with CPB.

DESIGN

Intervention case study.

METHODS

19 patients (12 males, 7 females) aged 70.1 +/- 6.1 yr (age range 62-80) with coronary artery disease and an ejection fraction <40% who underwent cardiac surgery. Cortisol (Cort), DHEA, DHEAS, LH, estradiol (E2), total testosterone (Te), SHBG, IGF-I were measured the day before, on the day of the procedure and 1, 2, 3, 4, and 30 days after CABG.

RESULTS

After surgery, serum IGF-I levels decreased (p<0.001), while levels of Cort, DHEAS and E2 significantly increased in both men and women. Alterations in Te levels differed between the two sexes with a significant decline in men and a significant increment in women.

CONCLUSION

CABG with CPB resulted in a dramatic drop in Te levels in old men and a significant decline in IGF-I in both sexes. Serum Cort levels also significantly increased in both sexes. These hormonal changes may, at least partially, explain why the elderly need prolonged rehabilitation after CABG.

THE ANTI-INFLAMMATORY EFFECT OF DIAZOXIDE IN CORONARY ARTERY BYPASS GRAFTING

Many therapeutic strategies have been designed to suppress the inflammatory response in patients undergoing coronary artery bypass grafting (CABG). Pharmacological preconditioning with diazoxide is an alternative in effective cardioprotective strategies, but more evidence is required to show its effect on the inflammatory response. Forty patients with stable angina who were scheduled for isolated elective CABG operations were randomized into control and diazoxide (DZX) groups. In the DZX group, 1.5 mg/kg diazoxide was infused intravenously in 5 min followed by a 5-min washout before commencing the cardiopulmonary bypass. In the control group, placebo infusion was given similarly. Blood samples for cytokine measurement were collected from the radial artery and coronary sinus perioperatively, and hemodynamic data were recorded. Thirty-six patients fulfilled the data collection. Cardiac index (CI) increased in both groups over time as compared with baseline. In the DZX group, the increase of CI was greater than that in the control group (P = 0.002). Systemic and coronary sinus plasma levels of IL-6, IL-8, and IL-10 increased significantly after reperfusion in both groups as compared with baseline (P < 0.05). IL-6 and IL-8 both reached the peak value at 6 h after cardiopulmonary bypass. IL-10 reached peak level at 20 min after reperfusion in both groups. There was significantly higher IL-10 in DZX groups (P = 0.015). The ratios of IL-6 to IL-10 and IL-8 to IL-10 were significantly lower in DZX groups than in controls (P = 0.025 and P = 0.041 for each, respectively). Pharmacological preconditioning with DZX in CABG patients shifts the circulating inflammatory cytokine balance toward the anti-inflammatory direction.