Role of therapeutic plasma exchange in the management of COVID-19-induced cytokine storm syndrome.

The risk of mortality in patients with coronavirus disease 2019 (COVID-19) is largely related to an excessive immune response, resulting in a hyperinflammatory and hypercoagulable condition collectively referred to as cytokine storm syndrome (CSS). Management of critically ill patients with COVID-19 has included attempts to abate this process, prevent disease progression, and reduce mortality. In this context, therapeutic plasma exchange (TPE) offers an approach to eliminate inflammatory factors and cytokines, offset the pathologic coagulopathy, and reduce the CSS effects. The aim of this review is to analyze available data on the use of TPE for the treatment of CSS in patients with COVID-19. Systematic searches of PubMed, Scopus and COVID-19 Research were conducted to identify articles published between March 1, 2020 and May 26, 2021 reporting the use of TPE for the treatment of COVID-19-induced CSS. A total of 34 peer-reviewed articles (1 randomized controlled trial, 4 matched case-control series, 15 single-group case series, and 14 case reports), including 267 patients, were selected. Despite the low evidence level of the available data, TPE appeared to be a safe intervention for critically ill patients with COVID-19-induced CSS. Although inconsistencies exist between studies, they showed a general trend for decreased interleukin-6, C-reactive protein, ferritin, D-dimer, and fibrinogen levels and increased lymphocyte counts following TPE, supporting the immunomodulatory effect of this treatment. Moreover, TPE was associated with improvements in clinical outcomes in critically ill patients with COVID-19. While TPE may offer a valuable option to treat patients with COVID-19-induced CSS, high-quality randomized controlled clinical trials are needed to confirm its potential clinical benefits, feasibility, and safety. Moreover, clear criteria should be established to identify patients with CSS who might benefit from TPE.

Lessons learned from the use of convalescent plasma for the treatment of COVID-19 and specific considerations for immunocompromised patients.

Coronavirus disease 2019 (COVID-19) convalescent plasma (CovCP) infusions have been widely used for the treatment of hospitalized patients with COVID-19. The aims of this narrative review were to analyze the safety and efficacy of CovCP infusions in the overall population and in immunocompromised patients with COVID-19 and to identify the lessons learned concerning the use of convalescent plasma (CP) to fill treatment gaps for emerging viruses. Systematic searches (PubMed, Scopus, and COVID-19 Research) were conducted to identify peer-reviewed articles and pre-prints published between March 1, 2020 and May 1, 2021 on the use of CovCP for the treatment of patients with COVID-19. From 261 retrieved articles, 37 articles reporting robust controlled studies in the overall population of patients with COVID-19 and 9 articles in immunocompromised patients with COVID-19 were selected. While CovCP infusions are well tolerated in both populations, they do not seem to improve clinical outcomes in critically-ill patients with COVID-19 and no conclusion could be drawn concerning their potential benefits in immunocompromised patients with COVID-19. To be better prepared for future epidemics/pandemics and to evaluate potential benefits of CP treatment, only CP units with high neutralizing antibodies (NAbs) titers should be infused in patients with low NAb titers, patient eligibility criteria should be based on the disease pathophysiology, and measured clinical outcomes and methods should be comparable across studies. Even if CovCP infusions did not improve clinical outcomes in patients with COVID-19, NAb-containing CP infusions remain a safe, widely available and potentially beneficial treatment option for future epidemics/pandemics.

Influence of vascular access devices upon efficiency of therapeutic plasma exchange.

BACKGROUND: An efficient vascular access is mandatory for the proper conduction of therapeutic plasma exchanges (TPE). Peripheral and central venous catheters may be used, with respective advantages and limitations. In this study, vascular access devices (IV catheter, dialysis cannula, central venous catheter) and anatomic vein characteristics were evaluated. METHOD: From January to June 2016, 162 TPE in 29 patients were reviewed. Only TPE using centrifugation method (Spectra Optia apheresis system) were evaluated. Volume exchanged, procedure duration, mean flow rate, number of inlet, and return pressure pauses were recorded. Site, width, and depth of punctured veins were studied. RESULTS: Median exchange volume planned was 3500 mL, and 152 (94%) procedures could be completed. Peripheral venous catheter was inserted in 103 (64%) cases (IV catheter: 61, dialysis cannulae: 42). Ultrasound guidance was used in 12 (11%) cases. Median procedure duration was shorter with central venous catheter (94 minutes), rather than dialysis cannula (133 minutes) or IV catheter (133 minutes). Median numbers of inlet pressure pauses were lower with central venous catheter (0) and dialysis cannulae (6), rather than IV catheter (10). There were no complications with peripheral venous access. There were no anatomic differences between catheterized veins with IV catheter or dialysis cannula. CONCLUSION: The use of peripheral venous access is possible in most of TPE, for emergency and during maintenance therapy. Dialysis cannulae are good compromise between classic IV catheters and central venous catheters, as it allows high flow rates, are easy to insert and associated with few complications.

Enzymatic cleavage specificity of the proalpha1(V) chain processing analysed by site-directed mutagenesis.

The proteolytic processing of procollagen V is complex and depends on the activity of several enzymes among which the BMP-1 (bone morphogenetic protein-1)/tolloid metalloproteinase and the furin-like proprotein convertases. Few of these processing interactions could have been predicted by analysing the presence of conserved consensus sequences in the proalpha1(V) chain. In the present study we opted for a cell approach that allows a straightforward identification of processing interactions. A construct encompassing the complete N-terminal end of the proalpha1(V) chain, referred to as Nalpha1, was recombinantly expressed to be used for enzymatic assays and for antibody production. Structural analysis showed that Nalpha1 is a monomer composed of a compact globule and an extended tail, which correspond respectively to the non-collagenous Nalpha1 subdomains, TSPN-1 (thrombospondin-1 N-terminal domain-like) and the variable region. Nalpha1 was efficiently cleaved by BMP-1 indicating that the triple helix is not required for enzyme activity. By mutating residues flanking the cleavage site, we showed that the aspartate residue at position P2' is essential for BMP-1 activity. BMP-1 activity at the C-terminal end of the procollagen V was assessed by generating a furin double mutant (R1584A/R1585A). We showed that, in absence of furin activity, BMP-1 is capable of processing the C-propeptide even though less efficiently than furin. Altogether, our results provide new relevant information on this complex and poorly understood mechanism of enzymatic processing in procollagen V function.

Structural requirements for heparin/heparan sulfate binding to type V collagen.

Collagen-proteoglycan interactions participate in the regulation of matrix assembly and in cell-matrix interactions. We reported previously that a fragment (Ile824-Pro950) of the collagen alpha1(V) chain, HepV, binds to heparin via a cluster of three major basic residues, Arg912, Arg918, and Arg921, and two additional residues, Lys905 and Arg909 (Delacoux, F., Fichard, A., Cogne, S., Garrone, R., and Ruggiero, F. (2000) J. Biol. Chem. 275, 29377-29382). Here, we further characterized the binding of HepV and collagen V to heparin and heparan sulfate by surface plasmon resonance assays. HepV bound to heparin and heparan sulfate with a similar affinity (KD approximately 18 and 36 nM, respectively) in a cation-dependent manner, and 2-O-sulfation of heparin was shown to be crucial for the binding. An octasaccharide of heparin and a decasaccharide of heparan sulfate were required for HepV binding. Studies with HepV mutants showed that the same basic residues were involved in the binding to heparin, to heparan sulfate, and to the cell surface. The contribution of Lys905 and Arg909 was found to be significant. The triple-helical peptide GPC(GPP)5G904-R918(GPP)5GPC-NH2 and native collagen V molecules formed much more stable complexes with heparin than HepV, and collagen V bound to heparin/heparan sulfate with a higher affinity (in the nanomolar range) than HepV. Heat and chemical denaturation strongly decreased the binding, indicating that the triple helix plays a major role in stabilizing the interaction with heparin. Collagen V and HepV may play different roles in cell-matrix interactions and in matrix assembly or remodeling mediated by their specific interactions with heparan sulfate.