The goal of this clinical trial is to investigate the immunomodulatory effects of the drugs dexamethasone, tocilizumab and anakinra in healthy male subjects aged 18 to 35 undergoing experimental endotoxemia. The main questions it aims to answer are:

• What are the effects of these drugs on the development of immunoparalysis in a repeated human endotoxemia model?
• What is the extent of the neuroinflammatory response and how do these drugs affect neuroinflammation in a repeated human endotoxemia model?

Researchers will compare these drugs to a placebo (a look-alike substance that contains no drug).

Participants will visit the Intensive Care research department on two or five occasions (screening included):

• The intervention group will receive an LPS challenge twice, with a week in between. Before the first LPS challenge, one of the described drugs will be administered. Blood, saliva and tear fluid will be collected regularly during the LPS challenge. Cerebrospinal fluid will also be collected through a catheter in the spinal cord.
• The control group will not receive an LPS challenge or drug administration and will have only one study day. During this day, blood, saliva, tear fluid and cerebrospinal fluid will be collected as regularly as during the LPS challenge of the intervention group.

During an LPS challenge, the investigators mimic blood poisoning by giving an endotoxin, also called LPS. This is a small part of the cell wall of a bacteria. This will cause transient flu-like symptoms for 3-4 hours.

The experimental human endotoxemia model is a controlled, standardized and safe model of systemic (sepsis-like) inflammation induced by bacterial lipopolysaccharide (LPS) in healthy volunteers. This model captures many hallmarks of both the hyperinflammatory phenotype (observed following a first LPS challenge) and the immunoparalytic phenotype (observed following a second LPS challenge one week later) of sepsis.

In this study the investigators aim to determine the effects of dexamethasone, tocilizumab and anakinra within the repeated experimental human endotoxemia model on the development of immunoparalysis, reflected by between-group differences in plasma TNF (and other cytokine) concentrations upon the second LPS challenge. The investigators will also profile inflammatory parameters in cerebrospinal fluid (CSF), reflected by within- and between-group differences in CSF TNF (and other cytokine) concentrations following the first LPS challenge, to gain insights in inflammatory responses of the central nervous system.

Anti-inflammatory drugs may help reduce sepsis-induced immunoparalysis and, somewhat counterintuitively, improve immune responses later by dampening the initial hyperinflammation. Pro-inflammatory cytokines, such as TNF, are key in triggering this immunosuppression. Reducing early hyperinflammation could also prevent postoperative immune suppression, lowering the risk of infections. Drugs like dexamethasone, tocilizumab, and anakinra may affect neuroinflammation, depending on their ability to cross the blood-brain barrier (BBB).

Furthermore, the investigators will explore whether cytokine profiles in saliva and tear fluid can be used as a proxy for circulating cytokine responses. Saliva and tear fluid cytokines may serve as non-invasive alternatives to blood measurements, especially for vulnerable populations, though more research is needed to validate their reliability.

Comprehensive assessment of cellular components and cytokine dynamics in blood, CSF, saliva, and tear fluid will be conducted using RNA sequencing, providing insights into cellular and molecular mechanisms during endotoxemia and drug effects. This research will help identify new drug targets and better understand the immunomodulatory effects of dexamethasone, tocilizumab, and anakinra on inflammation and immunosuppression.

Inclusion Criteria:

• Male subjects aged ≥18 and ≤35 years
• Body mass index (BMI) ≥18 and ≤30 kg/m2
• Healthy (as determined by medical history, physical examination, vital signs, 12-lead electrocardiogram and routine clinical laboratory parameters)
• Able to comprehend and sign the Information letter and Informed Consent (IC) prior to enrolment in the study.

Exclusion Criteria:

• Use of any prescription medication or over-the-counter non-steroidal anti-inflammatory drugs

• Known anaphylaxis or hypersensitivity to any (non-)investigational products or their excipients

• History of chronic headache or previous post-dural puncture headache (PDPH)

• History or signs of severe atopic syndrome (asthma, rhinitis with medication and/or eczema)

• History of any disease associated with immune deficiency

• History of cancer in the last 5 years (excluding localised skin cancer or carcinoma in situ)

• History or signs of haematological disease

• History or signs of thromboembolic disorders

• History of peptic / gastric ulcer disease

• History of psychiatric disorders

• Thrombocytopenia (<150*109/mL) or anaemia (<8.0 mmol/L)

• History, signs or symptoms of cardiovascular disease, in particular:

  • Prone to vagal collapse
  • History of atrial or ventricular arrhythmia
  • Cardiac conduction abnormalities on the ECG consisting of a 2nd degree atrio-ventricular block or a complete left bundle branch block
  • Hypertension (defined as RR systolic > 160 or RR diastolic > 90 mmHg)
  • Hypotension (defined as RR systolic < 100 or RR diastolic < 50 mmHg)

• Renal impairment (defined as plasma creatinine >120 μmol/L)

• Liver enzyme abnormalities (above 2x the upper limit of normal)

• Signs of infection (CRP > 20 mg/L, white blood cells > 12x109/L or

  • lt; 4x109/L)

• Clinically significant acute illness, including infections or trauma, within 1 month prior to the first LPS challenge

• Previous (participation in a study with) endotoxin (LPS) administration

• Participation in an experimental intervention or drug trial within 3 months prior to the first LPS challenge

• Any vaccination or blood donation within 1 month prior to the first LPS challenge

• Recent hospital admission or surgery with general anaesthesia within 3 months prior to the first LPS challenge

• Use of recreational drugs within 2 weeks prior to the first LPS challenge

• Suspected of not being able to comply with the trial protocol

• Inability to personally provide written informed consent (e.g. for linguistic or mental reasons) and/or take part in the study

• Demographic data (pseudonimized)
• Outcome data (pseudonimized)

Beginning directly after publication of the paper describing the main results of the study and ending 30 years after publication of the paper describing the main results.

Data will be made available upon reasonable request to the corresponding author.