Immunonutrition in intensive care has not yet demonstrated a beneficial effect on organ failure, the acquisition of nosocomial infections, or mortality. It did not correct for acquired immunosuppression in intensive care patients. Despite numerous methodological problems (use of several pharmaconutrients, very heterogeneous set of patients) and the absence of clinical data, deleterious effects have been attributed to immunonutrition in intensive care, in particular in septic patients and patients in intensive care . Arginine (ARG) is a semi-essential amino acid involved in many immunological mechanisms. It is synthesized in sufficient quantity under normal conditions but quickly becomes insufficient under catabolic conditions such as in severe sepsis. Arginine is not only the precursor of nitrogen monoxide (NO) but also an essential substrate for numerous enzymatic reactions which participate in the maintenance of immune homeostasis, in particular T lymphocyte function. Depletion of the cellular medium in arginine will induce an abnormality in the metabolism of immune cells responsible for a dysfunction of these cells (lymphopenia linked to early apoptosis) and thus expose patients to organ failure and nosocomial infections.

It has been found that hypoargininemia in intensive care patients is associated with the persistence of organ dysfunction (SOFA score), the occurrence of nosocomial infections and mortality. Also, it has been demonstrated that in these patients, enteral administration of ARG was not deleterious and increased ornithine synthesis, suggesting a preferential use of ARG via the arginases route, without significant increase in argininaemia or effect on immune functions. L-citrulline (CIT), an endogenous precursor of ARG, constitutes an interesting alternative for increasing the availability of ARG. Sponsor recent data demonstrate that the administration of CIT in intensive care is not deleterious and that it very significantly reduces mortality in an animal model of sepsis, corrects hypoargininemia, with convincing data on immunological parameters such as lymphopenia, which is associated with mortality, organ dysfunction and the occurrence of nosocomial infections. The availability of ARG directly impacts the mitochondrial metabolism of T lymphocytes and their function. Our hypothesis is therefore that CIT supplementation is more effective than administration of ARG in correcting hypoargininemia, reducing lymphocyte dysfunction, correcting immunosuppression and organ dysfunction in septic patients admitted to intensive care.

Strategy :

Enteral administration of citrulline for 5 days versus iso-nitrogenous placebo. Amino acid assay and immunological parameters (monocytic expression of HLA-DR, MDSCs, cytokines / chemokines, lymphocyte number and phenotype, apoptosis and lymphocyte proliferation and mitochondrial function and T lymphocyte repertoire) will only be carried out on patients included in Rennes (60 patients).

Inclusion Criteria:

• Septic patients in accordance with the definition of sepsis and septic shock published in 2016 (JAMA) and whose use is recommended by the European Society of Intensive Care Medicine;
• Initial aggression dated less than 4 days before admission to intensive care (selection of "community" patients). The onset of aggression will be defined by the onset of clinical signs of infection;
• Patients hospitalized for less than 48 hours before admission to intensive care (selection of patients without malnutrition and immunosuppression acquired in hospital) *;
• Patients under invasive mechanical ventilation with a foreseeable ventilation duration> 2 days **;
• Exclusive enteral nutrition;
• Affiliation to a social security scheme;
• Consent signed by the patient, relative or legal representative or inclusion under emergency procedure

Non Inclusion Criteria:

• Progressive Sars-CoV2 infection
• Pregnancy in progress;
• Morbid obesity (BMI> 40);
• State of immunosuppression defined by at least one of these criteria: continuous administration of steroids at any dose for more than one month before hospitalization, steroids at high doses (> 0.5 mg / kg / day of methylprednisolone or equivalent), radiotherapy or chemotherapy in the previous year, proven humoral or cellular deficiency;
• Contraindication to enteral nutrition (SRLF 2016 recommendations: "Enteral nutrition should probably not be used upstream of a high flow digestive fistula in cases of intestinal obstruction, ischemia of the small intestine or digestive hemorrhage. active (Strong agreement) ");
• Participation in intervention research on a drug, or intervention research that could impact the immune system

Exclusion Criteria:

- Institution of immunosuppressive therapy such as chemotherapy, cyclophosphamide, high dose corticosteroid therapy (> 0.5 mg / kg / day ; hydrocortisone used in the management of septic shock is not considered an exclusion criterion).

Prospective, multicenter, placebo-controlled, randomized, double-blind study on two parallel groups.