BackgroundThe complement system is an essential component of our innate defense and plays a vital role in the pathogenesis of many diseases. Assessment of complement activation is critical in monitoring both disease progression and response to therapy. Complement analysis requires accurate and standardized sampling and assay procedures, which has proven to be challenging.ObjectiveWe performed a systematic analysis of the current methods used to assess complement components and reviewed whether the identified studies performed their complement measurements according to the recommended practice regarding pre-analytical sample handling and assay technique. Results are supplemented with own data regarding the assessment of key complement biomarkers to illustrate the importance of accurate sampling and measuring of complement components.MethodsA literature search using the Pubmed/MEDLINE database was performed focusing on studies measuring the key complement components C3, C5 and/or their split products and/or the soluble variant of the terminal C5b-9 complement complex (sTCC) in human blood samples that were published between February 2017 and February 2022. The identified studies were reviewed whether they had used the correct sample type and techniques for their analyses.ResultsA total of 92 out of 376 studies were selected for full-text analysis. Forty-five studies (49%) were identified as using the correct sample type and techniques for their complement analyses, while 25 studies (27%) did not use the correct sample type or technique. For 22 studies (24%), it was not specified which sample type was used.ConclusionA substantial part of the reviewed studies did not use the appropriate sample type for assessing complement activation or did not mention which sample type was used. This deviation from the standardized procedure can lead to misinterpretation of complement biomarker levels and hampers proper comparison of complement measurements between studies. Therefore, this study underlines the necessity of general guidelines for accurate and standardized complement analysis

Nontuberculous mycobacteria (NTM) are highly drug-resistant, opportunistic pathogens that can cause pulmonary disease. The outcomes of the currently recommended treatment regimens are poor, especially for Mycobacterium abscessus. New or repurposed drugs are direly needed. Auranofin, a gold-based antirheumatic agent, was investigated for Mycobacterium tuberculosis. Here, we test auranofin against NTM in vitro and ex vivo. We tested the susceptibility of 63 NTM isolates to auranofin using broth microdilution. Next, we assessed synergy between auranofin and antimycobacterial drugs using the checkerboard method and calculated the fractional inhibition concentration index (FICI). Using time-kill kinetics assays (TK), we assessed pharmacodynamics of auranofin alone and in combination with drug combinations showing the lowest FICIs for M. abscessus CIP 104536. A response surface analysis was used to assess synergistic interactions over time in TKs. Primary isolated macrophages were infected with M. abscessus and treated with auranofin. Finally, using KEGG Orthology, we looked for orthologues to auranofins drug target in M. tuberculosis. M. abscessus had the lowest auranofin MIC50 (2 μg/ml) among the tested NTM. The lowest average FICIs were observed between auranofin and amikacin (0.45) and linezolid (0.50). Auranofin exhibited concentration-dependent killing of M. abscessus, with >1-log killing at concentrations of >2× MIC. Only amikacin was synergistic with auranofin according to Bliss independence. Auranofin could not lower the intracellular bacterial load in macrophages. Auranofin itself may not be feasible for M. abscessus treatment, but these data point toward a promising, unutilized drug target.

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Objective: Chloroquine has been frequently administered for treatment of coronavirus disease 2019 but there are serious concerns about its efficacy and cardiac safety. Our objective was to investigate the pharmacokinetics and safety of chloroquine in hospitalized COVID-19 patients. Design: A prospective observational study. Setting: Dutch hospitals Patients: Patients admitted to the hospital for treatment of COVID-19. Interventions: Pharmacokinetic sampling Measurements: The plasma concentrations of chloroquine and desethylchloroquine and QTc time. Main Results: A total of 83 patients were included. The median (IQR) plasma concentration chloroquine during treatment was 1.05 μmol/L (0.63 - 1.55 μmol/L). None of the patients reached exposure exceeding the concentration to inhibit SARS-CoV-2 replication by 90% (IC90) of 6.9 μM. Furthermore, ΔQTc >60 milliseconds occurred after initiation of chloroquine treatment in 34% patients and during treatment QTc ≥500 milliseconds was observed in 46% of patients. Conclusions: Recommended dose chloroquine treatment results in plasma concentrations that are unlikely to inhibit viral replication. Furthermore, the incidence of QTc prolongation was high. The preclinical promise of chloroquine as antiviral treatment in patients with COVID-19 is overshadowed by its cardiac toxicity and lack of effective exposure. It is unlikely that a positive clinical effect will be found with chloroquine for treatment of COVID-19.