Effects of Vasopressors on Immune Response

The Effects of Different Vasopressors on the Innate Immune Response During Experimental Human Endotoxemia, a Pilot Proof-of-principle Study

Noradrenaline is a catecholamine and the cornerstone treatment for the improvement of hemodynamic parameters in septic shock. Catecholamines exert profound immunomodulatory effects. Noradrenaline in vitro inhibits LPS-induced pro-inflammatory cytokine production, however, the actions on immune function in vivo have not been assessed. Furthermore, effects on the immune system of viable vasopressor alternatives for the treatment of septic patients, namely phenylephrine and vasopressin, need to be established in humans in vivo.

Rationale: Septic shock is a major medical challenge associated with a high mortality rate and increasing incidence. It has become clear that the majority of septic patients do not succumb to an initial pro-inflammatory "hit", but at a later time-point in a pronounced immunosuppressive state, so called 'immunoparalysis'. Noradrenaline is a catecholamine and the cornerstone treatment for the improvement of hemodynamic parameters in septic shock. However, catecholamines exert profound immunomodulatory effects which have mainly been studied for adrenaline. It profoundly inhibits LPS-induced production of TNF-α, and enhances production of anti-inflammatory IL-10 in vitro, as well as in animal and human models of inflammation. Although in vitro studies have shown that noradrenaline inhibits LPS-induced pro-inflammatory cytokine production as potently as adrenaline, the effects of noradrenaline on the immune system in vivo have not yet been studied. Furthermore, effects on the immune system of viable vasopressor alternatives for the treatment of septic patients, namely phenylephrine and vasopressin, need to be established in humans in vivo. Objective: To investigate whether noradrenaline exerts immunomodulatory effects in humans in vivo and to compare noradrenaline to other vasopressors (phenylephrine and vasopressin). Study design: A randomized double-blind placebo-controlled study in healthy human volunteers during experimental endotoxemia. Study population: 40 healthy male volunteers, aged 18-35 yrs. Intervention: The noradrenaline group (n= 10): subjects that will receive intravenous infusion of noradrenaline 0.05 μg/kg/min for 5 hours, starting 60 minutes before intravenous administration of 2 ng/kg LPS. The phenylephrine group (n=10): subjects that will receive intravenous infusion of phenylephrine 0.5 μg/kg/min for 5 hours, starting 60 minutes before intravenous administration of 2 ng/kg LPS. . The vasopressin group (n = 10): subjects that will receive intravenous infusion of vasopressin 0.04 IU/min for 5 hours, starting 60 minutes before intravenous administration of 2 ng/kg LPS. The placebo group (n = 10): subjects that will receive intravenous infusion of NaCl 0.9% for 5 hours, starting 60 minutes before intravenous administration of 2 ng/kg LPS. Main parameters/endpoints: The difference of LPS-induced TNF-α plasma concentrations following endotoxemia between the noradrenaline and the placebo groups

The noradrenaline group: a group of 10 subjects that will receive noradrenaline 0.05 μg/kg/min infusion for 5 hours, starting 60 minutes before endotoxin administration.

The vasopressin group: a group of 10 subjects that will receive vasopressin 0.04 IU/min infusion for 5 hours, starting 60 minutes before endotoxin administration.

The phenylephrine group: a group of 10 subjects that will receive phenylephrine 0.5 μg/kg/min infusion for 5 hours, starting 60 minutes before endotoxin administration.

The placebo group: a group of 10 subjects that will receive NaCl 0.9% infusion for 5 hours, starting 60 minutes before endotoxin administration.

Noradrenaline is an endogenous catecholamine with sympathomimetic effects. It has mainly α-adrenergic receptor selectivity but also β-effects in higher concentrations. It will be administered at 0.05 μg/kg/min, a clinical relevant dose on the low end of the scale.

Phenylephrine is a selective α-adrenergic receptor agonist. It will be administered at 0.5 μg/kg/min, based on its relative vasopressor potency in comparison with noradrenaline.

Vasopressin is 8-arginine-vasopressin, a synthetic analogue of endogenous nonapeptide hormone. It exerts its action via V1 receptors (ubiquitous vasoconstriction) and V2 receptors (renal water resorption). It will be administered at 0.04 IU/min, a clinically relevant dose.

concentration plasma TNFalpha (pg/ml) following endotoxemia between the noradrenaline and the placebo groups

Comparison between health patch device, and 2 phone applications and a subjective stress questionaire

Inclusion Criteria: Written informed consent Age ≥18 and ≤35 yrs Male Healthy Exclusion Criteria: Use of any medication Smoking Previous spontaneous vagal collapse History of atrial or ventricular arrhythmia (Family) history of myocardial infarction or stroke under the age of 65 years Cardiac conduction abnormalities on the ECG consisting of a 2nd degree atrioventricular block or a complex bundle branch block Hypertension (defined as RR systolic > 160 or RR diastolic > 90) Hypotension (defined as RR systolic < 100 or RR diastolic < 50) Renal impairment (defined as plasma creatinin >120 μmol/l) Liver enzyme abnormalities Medical history of any disease associated with immune deficiency CRP > 20 mg/L, WBC > 12x109/L, or clinically significant acute illness, including infections, within 4 weeks before endotoxin administration Participation in a drug trial or donation of blood 3 months prior to the LPS challenge Use of recreational drugs within 7 days prior to experiment day Recent hospital admission or surgery with general anaesthesia (<3 months) Known anaphylaxis or hypersensitivity to the study drugs or their excipients Recent anaesthesia with halogenated agents Known cardiovascular disease (coronary artery disease) Known chronic nephritis

Stolk RF, Naumann F, van der Pasch E, Schouwstra J, Bressers S, van Herwaarden AE, Gerretsen J, Schambergen R, Ruth M, van der Hoeven HG, van Leeuwen HJ, Pickkers P, Kox M. Phenylephrine impairs host defence mechanisms to infection: a combined laboratory study in mice and translational human study. Br J Anaesth. 2021 Mar;126(3):652-664. doi: 10.1016/j.bja.2020.11.040. Epub 2021 Jan 20.

van Loon LM, Stolk RF, van der Hoeven JG, Veltink PH, Pickkers P, Lemson J, Kox M. Effect of Vasopressors on the Macro- and Microcirculation During Systemic Inflammation in Humans In Vivo. Shock. 2020 Feb;53(2):171-174. doi: 10.1097/SHK.0000000000001357.