SARS-CoV-2-Induced ARDS Associates with MDSC Expansion, Lymphocyte Dysfunction, and Arginine Shortage.

PURPOSE: The SARS-CoV-2 infection can lead to a severe acute respiratory distress syndrome (ARDS) with prolonged mechanical ventilation and high mortality rate. Interestingly, COVID-19-associated ARDS share biological and clinical features with sepsis-associated immunosuppression since lymphopenia and acquired infections associated with late mortality are frequently encountered. Mechanisms responsible for COVID-19-associated lymphopenia need to be explored since they could be responsible for delayed virus clearance and increased mortality rate among intensive care unit (ICU) patients. METHODS: A series of 26 clinically annotated COVID-19 patients were analyzed by thorough phenotypic and functional investigations at days 0, 4, and 7 after ICU admission. RESULTS: We revealed that, in the absence of any difference in demographic parameters nor medical history between the two groups, ARDS patients presented with an increased number of myeloid-derived suppressor cells (MDSC) and a decreased number of CD8pos effector memory cell compared to patients hospitalized for COVID-19 moderate pneumonia. Interestingly, COVID-19-related MDSC expansion was directly correlated to lymphopenia and enhanced arginase activity. Lastly, T cell proliferative capacity in vitro was significantly reduced among COVID-19 patients and could be restored through arginine supplementation. CONCLUSIONS: The present study reports a critical role for MDSC in COVID-19-associated ARDS. Our findings open the possibility of arginine supplementation as an adjuvant therapy for these ICU patients, aiming to reduce immunosuppression and help virus clearance, thereby decreasing the duration of mechanical ventilation, nosocomial infection acquisition, and mortality.

Bacterial and fungal infections: a frequent and deadly complication among critically ill acute liver failure patients.

BACKGROUND: Acute liver failure (ALF) is a rare but life-threatening condition mostly requiring intensive care unit (ICU) admission. ALF induces immune disorders and may promote infection acquisition. However, the clinical spectrum and impact on patients' prognosis remain poorly explored. METHODS: We conducted a retrospective single-centre study on patients admitted for ALF to the ICU of a referral University Hospital from 2000 to 2021. Baseline characteristics and outcomes according to the presence of infection until day 28 were analysed. Risk factors for infection were determined using logistic regression. The impact of infection on 28-day survival was assessed using the proportional hazard Cox model. RESULTS: Of the 194 patients enrolled, 79 (40.7%) underwent infection: community-acquired, hospital-acquired before ICU and ICU-acquired before/without and after transplant in 26, 23, 23 and 14 patients, respectively. Most infections were pneumonia (41.4%) and bloodstream infection (38.8%). Of a total of 130 microorganisms identified, 55 were Gram-negative bacilli (42.3%), 48 Gram-positive cocci (36.9%) and 21 were fungi (16.2%). Obesity (OR 3.77 [95% CI 1.18-14.40]; p = .03) and initial mechanical ventilation (OR 2.26 [95% CI 1.25-4.12]; p = .007) were independent factors associated with overall infection. SAPSII > 37 (OR 3.67 [95% CI 1.82-7.76], p < .001) and paracetamol aetiology (OR 2.10 [95% CI 1.06-4.22], p = .03) were independently associated with infection at admission to ICU. On the opposite, paracetamol aetiology was associated with lower risk of ICU-acquired infection (OR 0.37 [95% CI 0.16-0.81], p = .02). Patients with any type of infection had lower day 28 survival rates (57% versus 73%; HR 1.65 [1.01-2.68], p = .04). The presence of infection at ICU admission (p = .04), but not ICU-acquired infection, was associated with decreased survival. CONCLUSIONS: The prevalence of infection is high in ALF patients which is associated with a higher risk of death. Further studies assessing the use of early antimicrobial therapy are needed.

Influenza- and COVID-19-Associated Pulmonary Aspergillosis: Are the Pictures Different?

Invasive pulmonary aspergillosis (IPA) in intensive care unit patients is a major concern. Influenza-associated acute respiratory distress syndrome (ARDS) and severe COVID-19 patients are both at risk of developing invasive fungal diseases. We used the new international definitions of influenza-associated pulmonary aspergillosis (IAPA) and COVID-19-associated pulmonary aspergillosis (CAPA) to compare the demographic, clinical, biological, and radiological aspects of IAPA and CAPA in a monocentric retrospective study. A total of 120 patients were included, 71 with influenza and 49 with COVID-19-associated ARDS. Among them, 27 fulfilled the newly published criteria of IPA: 17/71 IAPA (23.9%) and 10/49 CAPA (20.4%). Kaplan-Meier curves showed significantly higher 90-day mortality for IPA patients overall (p = 0.032), whereas mortality did not differ between CAPA and IAPA patients. Radiological findings showed differences between IAPA and CAPA, with a higher proportion of features suggestive of IPA during IAPA. Lastly, a wide proportion of IPA patients had low plasma voriconazole concentrations with a higher delay to reach concentrations > 2 mg/L in CAPA vs. IAPA patients (p = 0.045). Severe COVID-19 and influenza patients appeared very similar in terms of prevalence of IPA and outcome. The dramatic consequences on the patients' prognosis emphasize the need for a better awareness in these particular populations.

Is the COVID-19 Pandemic a Good Time to Include Aspergillus Molecular Detection to Categorize Aspergillosis in ICU Patients? A Monocentric Experience.

(1) Background: The diagnosis of invasive aspergillosis (IA) in an intensive care unit (ICU)remains a challenge and the COVID-19 epidemic makes it even harder. Here, we evaluatedAspergillus PCR input to help classifying IA in SARS-CoV-2-infected patients. (2) Methods: 45COVID-19 patients were prospectively monitored twice weekly for Aspergillus markers and anti-Aspergillus serology. We evaluated the concordance between (Ι) Aspergillus PCR and culture inrespiratory samples, and (ΙΙ) blood PCR and serum galactomannan. Patients were classified asputative/proven/colonized using AspICU algorithm and two other methods. (3) Results: Theconcordance of techniques applied on respiratory and blood samples was moderate (kappa = 0.58and kappa = 0.63, respectively), with a higher sensitivity of PCR. According to AspICU, 9/45 patientswere classified as putative IA. When incorporating PCR results, 15 were putative IA because theymet all criteria, probably with a lack of specificity in the context of COVID-19. Using a modifiedAspICU algorithm, eight patients were classified as colonized and seven as putative IA. (4)Conclusion: An appreciation of the fungal burden using PCR and Aspergillus serology was addedto propose a modified AspICU algorithm. This proof of concept seemed relevant, as it was inagreement with the outcome of patients, but will need validation in larger cohorts.