Cimetidine reduces impairment of cellular immunity after cardiac operations with cardiopulmonary bypass

Repurposing drugs in oncology (ReDO)-cimetidine as an anti-cancer agent

Cimetidine, the first H₂ receptor antagonist in widespread clinical use, has anti-cancer properties that have been elucidated in a broad range of pre-clinical and clinical studies for a number of different cancer types. These data are summarised and discussed in relation to a number of distinct mechanisms of action. Based on the evidence presented, it is proposed that cimetidine would synergise with a range of other drugs, including existing chemotherapeutics, and that further exploration of the potential of cimetidine as an anti-cancer therapeutic is warranted. Furthermore, there is compelling evidence that cimetidine administration during the peri-operative period may provide a survival benefit in some cancers. A number of possible combinations with other drugs are discussed in the supplementary material accompanying this paper.

What is the optimum prophylaxis against gastrointestinal haemorrhage for patients undergoing adult cardiac surgery: histamine receptor antagonists, or proton-pump inhibitors?

A best evidence topic was written according to a structured protocol. The question addressed was what is the optimum prophylaxis against gastrointestinal haemorrhage for patients undergoing adult cardiac surgery: histamine receptor antagonists (H(2)RA) or proton-pump inhibitors? A total of 201 papers were found; of which, 8 represented the best evidence. The authors, date, journal, study type, population, main outcome measures and results were tabulated. Only one randomized controlled trial (RCT) with relevant clinical outcomes was identified. The rest of the studies consisted of five prospective studies and two retrospective studies. In the RCT, there were no reported cases of gastrointestinal haemorrhage in the proton-pump inhibitor cohort, whereas 4 patients taking H(2)RA developed it. The rate of active gastrointestinal ulceration was higher in the H(2)RA cohort in comparison with the proton-pump inhibitor cohort (21.4 vs 4.3%). A prospective study followed 2285 consecutive patients undergoing cardiac surgery who received either no prophylaxis, or a proton-pump inhibitor. Chi-squared analysis showed the risk of bleeding to be lower in those receiving the proton-pump inhibitor (P < 0.05). Another study of 6316 patients undergoing coronary artery bypass grafting demonstrated a reduced risk of gastrointestinal bleed with prophylactic intravenous omeprazole (odds ratio = 0.2; confidence intervals = 0.1-0.8; P < 0.05). One study successfully showed that proton-pump inhibitors are effective in adequately suppressing gastric acid levels, regardless of Helicobacter pylori infection status; conversely, this study suggested that H(2)RAs were not. The evidence for H(2)RAs is marginal, with no study showing a clear benefit. One study showed that ulcer prophylaxis with H(2)RA did not correlate with the clinical outcome. Another study demonstrated gastric ulceration to be a common gastrointestinal complication in spite of regular H(2)RA use. There is also evidence to suggest that acid suppression increases the risk of nosocomial pneumonia, although open heart surgery may be a confounding factor in this association. Two RCTs showed that H(2)RAs may augment the immune system and reducing stress following cardiac surgery. Proton-pump inhibitors appear to be the superior agent for prophylaxis against gastrointestinal bleed in patients undergoing cardiac surgery, although rigorous comparative data are sparse. Furthermore, level-I evidence would confirm this.

Prostaglandin el attenuates impairment of cellular immunity after cardiopulmonary bypass

OBJECTIVE

It is well documented that cardiopulmonary bypass (CPB) severely impairs cellular immunity. The objective of this study was to investigate the effect of prostaglandin E1 (PGE1) on cellular immunity after CPB.

METHODS

Patients who underwent elective cardiac surgery were randomly divided into the PGE1 group (n=12) and the control group (n=12). In the PGE1 group, PGE1 was administered at 20 ng/kg/min from just after the induction of anesthesia to the end of surgery. Peripheral blood mononuclear cells (PBMCs) were taken before anesthesia and on postoperative days 1, 3 and 7 (POD 1, POD 3 and POD 7). Proliferation responses of T cells to phytohemagglutinin (PHA) and pure protein derivative (PPD) antigen were measured as indicators of cellular immunity.

RESULTS

PGE1 significantly attenuated the impairment of both PHA and PPD response after cardiac surgery on POD 1 (PHA response, 30 +/- 21% vs. 53 +/- 32%, control vs. PGE, p=0.048; PPD response, 18 +/- 21% vs. 39 +/- 27%, control vs. PGE, p=0.046). The reduced glutathione content of PBMCs in the control group was significantly decreased on POD 1.

CONCLUSION

PGE1 attenuated the impairment of cellular immunity after cardiac surgery with CPB by reducing oxidative stress on PBMCs.

Potential prophylactic measures against postoperative immunosuppression: could they reduce recurrence rates in oncological patients?

BACKGROUND

Removing the primary tumor is indispensable for eliminating the major pool of metastasizing cells, but the surgical procedure itself is suspected of promoting metastases. This adverse effect is attributed to several mechanisms acting in synergy, including mechanical release of tumor cells, enhanced angiogenesis, secretion of growth factors, and immunosuppression. Here we provide new insights into mechanisms of postoperative immunosuppression and assess the assumptions underlying the hypothesis that, by suppressing cell-mediated immunity (CMI), surgery may render the patient vulnerable to metastases that otherwise could have been controlled.

METHODS

An extensive review of relevant articles in English identified by using the MEDLINE database and cross-referencing.

RESULTS

Current literature suggests that (1) CMI can control minimal residual disease, especially if surgery is performed early; (2) major surgery transiently but markedly suppresses CMI through multiple mechanisms now better understood; (3) surgical stress promotes experimental metastasis through immunosuppression, but the clinical evidence remains indirect because of ethical limitations.

CONCLUSIONS

Minimizing postoperative immunosuppression seems feasible, may limit recurrence, and should be introduced into the broader array of considerations when planning oncological surgeries. In the short run, physicians could try to avoid immunosuppressive anesthetic approaches, inadvertent hypothermia, excessive blood transfusions, and untended postoperative pain. When feasible, minimally invasive surgery should be considered. In the long run, clinical trials should evaluate prophylactic measures, including perioperative immunostimulation and several antagonists to cytokines and hormones specified herein.

Glucocorticoid involvement in suppression of NK activity following surgery in rats

We studied plasma factors mediating suppression of NK activity (NKA) following surgery. Plasma from operated rats suppressed NKA of splenocytes, leukocytes, and purified natural killer (NK) cells, and charcoal stripping nullified suppression. The glucocorticoid antagonist mifepristone prevented suppression, whereas blockers of reactive oxygen metabolites, opioids, catecholamines, prostaglandin-E2, and histamine did not. NKA dropped as corticosterone levels peaked postoperatively, and administration of relevant doses of corticosterone suppressed NKA. Inhibition of glucocorticoid synthesis prevented plasma from suppressing NKA but merely attenuated NKA suppression in operated rats. Thus, postoperative concentrations of corticosterone can directly suppress NKA but additional factors probably act in vivo.

High-dose cimetidine reduces proinflammatory reaction after cardiac surgery with cardiopulmonary bypass

BACKGROUND

Cimetidine, which is usually used for gastric ulcer, enhances cellular immunity. The effect of cimetidine on perioperative proinflammatory response after cardiac surgery with cardiopulmonary bypass was investigated.

METHODS

Elective coronary artery bypass graft cases in which CPB was performed were placed randomly in a cimetidine (C) group (n = 20) or a no-treatment (N) group (n = 20). The time course of plasma levels of neutrophil elastase, interleukin (IL)-6 and IL-8, leukocyte counts, lymphocyte recovery ratio, C-reactive protein, creatine-kinase-MB, and oxygenation index were analyzed.

RESULTS

The plasma levels of neutrophil elastase and IL-8 were inhibited in the C groups at 2 hours after CPB termination. In a comparison of the two groups, the C group demonstrated higher lymphocyte recovery ratio and lower C-reactive protein on postoperative day 5 and shorter intubation time. No intergroup differences were observed in IL-6, leukocyte counts, creatine-kinase-MB levels, or oxygenation index.

CONCLUSIONS

Cimetidine may reduce surgical stress and augment the immune system after cardiac surgery with cardiopulmonary bypass.

Changes in T-cell receptor subsets after cardiac surgery in children

T cells are divided into two subsets, alphabeta and gammadelta, according to the T-cell receptor (TCR) expressed. Recent findings indicate that gammadelta T cells serve as the first defense against microbial pathogens, and represent a link between innate and acquired immunity. We conducted a study to investigate the changes in circulating TCR subsets after cardiac surgery in children. Blood samples from 24 children who underwent cardiac surgery with cardiopulmonary bypass (CPB) were collected serially to analyze TCR subsets by flow cytometry. The alphabeta T cells reached a nadir on postoperative day (POD) 1, but recovered to pre-CPB levels on POD 3. On the other hand, the gammadelta T cells decreased after CPB and did not recover to pre-CPB levels even after POD 7. The alphabeta/gammadelta T-cell ratio was increased after POD 3. In children, gammadelta T cells recover more slowly than alphabeta T cells after cardiac surgery. These changes in TCR subsets may contribute to postoperative immunosuppression.