Selective C-reactive protein apheresis for Covid-19 patients suffering from organ damage

Endothelial Glycocalyx Injury in SARS-CoV-2 Infection: Molecular Mechanisms and Potential Targeted Therapy

This review aims at summarizing state-of-the-art knowledge on glycocalyx and SARS-CoV-2. The endothelial glycocalyx is a dynamic grid overlying the surface of the endothelial cell (EC) lumen and consists of membrane-bound proteoglycans and glycoproteins. The role of glycocalyx has been determined in the regulation of EC permeability, adhesion, and coagulation. SARS-CoV-2 is an enveloped, single-stranded RNA virus belonging to β-coronavirus that causes the outbreak and the pandemic of COVID-19. Through the respiratory tract, SARS-CoV-2 enters blood circulation and interacts with ECs possessing angiotensin-converting enzyme 2 (ACE2). Intact glycolyx prevents SARS-CoV-2 invasion of ECs. When the glycocalyx is incomplete, virus spike protein of SARS-CoV-2 binds with ACE2 and enters ECs for replication. In addition, cytokine storm targets glycocalyx, leading to subsequent coagulation disorder. Therefore, it is intriguing to develop a novel treatment for SARS-CoV-2 infection through the maintenance of the integrity of glycocalyx. This review aims to summarize state-of-the-art knowledge of glycocalyx and its potential function in SARS-CoV-2 infection.

[CRP apheresis in acute myocardial infarction and COVID-19]

C‑reactive protein (CRP) is the best-known acute phase protein. In humans, inflammation and infection are usually accompanied by an increase in CRP levels in the blood, which is why CRP is an important biomarker in daily clinical routine. CRP can mediate the initiation of phagocytosis by labeling damaged cells. This labeling leads to activation of the classical complement pathway (up to C4) and ends in the elimination of pathogens or reversibly damaged or dead cells. This seems to make sense in case of an external wound of the body. However, in the case of "internal wounds" (e.g., myocardial infarction, stroke), CRP induces tissue damage to potentially regenerable tissue by cell labeling, which has corresponding deleterious effects on cardiac and brain tissue or function. The described labeling of ischemic but potentially regenerable cells by CRP apparently also occurs in coronavirus disease 2019 (COVID-19). Parts of the lung become ischemic due to intra-alveolar edema and hemorrhage, and this is accompanied by a dramatic increase in CRP. Use of selective immunoadsorption of CRP from blood plasma ("CRP apheresis") to rapidly and efficiently lower the fulminant CRP load in the body fills this pharmacotherapeutic gap. With CRP apheresis, it is possible for the first time to remove this pathological molecule quickly and efficiently in clinical practice.

Seven COVID-19 Patients Treated with C-Reactive Protein (CRP) Apheresis

Background: The fulminant course of COVID-19, triggered by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), presents with a high mortality rate and still lacks a causative treatment. C-reactive protein (CRP) has been shown to increase dramatically during the disease progression and correlates with deleterious outcomes. Selective CRP apheresis can reduce circulating CRP levels fast and effective. Methods: Seven hospitalized patients with documented severe COVID-19 progression, elevated CRP plasma levels (>100 mg/L) and signs of respiratory failure were treated with CRP apheresis. Two to twelve CRP apheresis sessions were performed generally in 24 h time intervals and depending on CRP plasma levels. Results: All patients had comorbidities. CRP apheresis reduced CRP plasma levels by up to 84% within a few hours, without exhibiting side effects in any patient. Despite signs of severe lung infiltration in all patients, only one patient died. The other patients showed improvements within the chest X-ray after CRP apheresis and were able to recover regardless of intubation and/or ECMO (4 patients). All remaining six patients were discharged from the hospital in good clinical condition. Conclusions: This case series presents a mortality rate of only 14%, which is dramatically lower than expected from the presented CRP levels as well as comorbidities and ventilation requirements. Our clinical observations regarding the here presented seven patients support the hypothesis that CRP is a candidate to be therapeutically targeted in the early stage of severe COVID-19.

Targeting C-Reactive Protein by Selective Apheresis in Humans: Pros and Cons

C-reactive protein (CRP), the prototype human acute phase protein, may be causally involved in various human diseases. As CRP has appeared much earlier in evolution than antibodies and nonetheless partly utilizes the same biological structures, it is likely that CRP has been the first antibody-like molecule in the evolution of the immune system. Like antibodies, CRP may cause autoimmune reactions in a variety of human pathologies. Consequently, therapeutic targeting of CRP may be of utmost interest in human medicine. Over the past two decades, however, pharmacological targeting of CRP has turned out to be extremely difficult. Currently, the easiest, most effective and clinically safest method to target CRP in humans may be the specific extracorporeal removal of CRP by selective apheresis. The latter has recently shown promising therapeutic effects, especially in acute myocardial infarction and COVID-19 pneumonia. This review summarizes the pros and cons of applying this novel technology to patients suffering from various diseases, with a focus on its use in cardiovascular medicine.

Patients with COVID-19: in the dark-NETs of neutrophils

SARS-CoV-2 infection poses a major threat to the lungs and multiple other organs, occasionally causing death. Until effective vaccines are developed to curb the pandemic, it is paramount to define the mechanisms and develop protective therapies to prevent organ dysfunction in patients with COVID-19. Individuals that develop severe manifestations have signs of dysregulated innate and adaptive immune responses. Emerging evidence implicates neutrophils and the disbalance between neutrophil extracellular trap (NET) formation and degradation plays a central role in the pathophysiology of inflammation, coagulopathy, organ damage, and immunothrombosis that characterize severe cases of COVID-19. Here, we discuss the evidence supporting a role for NETs in COVID-19 manifestations and present putative mechanisms, by which NETs promote tissue injury and immunothrombosis. We present therapeutic strategies, which have been successful in the treatment of immunο-inflammatory disorders and which target dysregulated NET formation or degradation, as potential approaches that may benefit patients with severe COVID-19.

Case Report: C-Reactive Protein Apheresis in a Patient With COVID-19 and Fulminant CRP Increase

Background

Plasma levels of C-reactive protein (CRP), induced by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) triggering COVID-19, can rise surprisingly high. The increase of the CRP concentration as well as a certain threshold concentration of CRP are indicative of clinical deterioration to artificial ventilation. In COVID-19, virus-induced lung injury and the subsequent massive onset of inflammation often drives pulmonary fibrosis. Fibrosis of the lung usually proceeds as sequela to a severe course of COVID-19 and its consequences only show months later. CRP-mediated complement- and macrophage activation is suspected to be the main driver of pulmonary fibrosis and subsequent organ failure in COVID-19. Recently, CRP apheresis was introduced to selectively remove CRP from human blood plasma.

Case Report

A 53-year-old, SARS-CoV-2 positive, male patient with the risk factor diabetes type 2 was referred with dyspnea, fever and fulminant increase of CRP. The patient's lungs already showed a pattern enhancement as an early sign of incipient pneumonia. The oxygen saturation of the blood was ≤ 89%. CRP apheresis using the selective CRP adsorber (PentraSorb® CRP) was started immediately. CRP apheresis was performed via peripheral venous access on 4 successive days. CRP concentrations before CRP apheresis ranged from 47 to 133 mg/l. The removal of CRP was very effective with up to 79% depletion within one apheresis session and 1.2 to 2.14 plasma volumes were processed in each session. No apheresis-associated side effects were observed. It was at no point necessary to transfer the patient to the Intensive Care Unit or to intubate him due to respiratory failure. 10 days after the first positive SARS-CoV-2 test, CRP levels stayed below 20 mg/l and the patient no longer exhibited fever. Fourteen days after the first positive SARS-CoV-2 test, the lungs showed no sign of pneumonia on X-ray.

Conclusion

This is the first report on CRP apheresis in an early COVID-19 patient with fulminant CRP increase. Despite a poor prognosis due to his diabetes and biomarker profile, the patient was not ventilated, and the onset of pneumonia was reverted.

C-Reactive Protein Triggers Cell Death in Ischemic Cells

C-reactive protein (CRP) is the best-known acute phase protein. In humans, almost every type of inflammation is accompanied by an increase of CRP concentration. Until recently, the only known physiological function of CRP was the marking of cells to initiate their phagocytosis. This triggers the classical complement pathway up to C4, which helps to eliminate pathogens and dead cells. However, vital cells with reduced energy supply are also marked, which is useful in the case of a classical external wound because an important substrate for pathogens is disposed of, but is counterproductive at internal wounds (e.g., heart attack or stroke). This mechanism negatively affects clinical outcomes since it is established that CRP levels correlate with the prognosis of these indications. Here, we summarize what we can learn from a clinical study in which CRP was adsorbed from the bloodstream by CRP-apheresis. Recently, it was shown that CRP can have a direct effect on blood pressure in rabbits. This is interesting in regard to patients with high inflammation, as they often become tachycardic and need catecholamines. These two physiological effects of CRP apparently also occur in COVID-19. Parts of the lung become ischemic due to intra-alveolar edema and hemorrhage and in parallel CRP increases dramatically, hence it is assumed that CRP is also involved in this ischemic condition. It is meanwhile considered that most of the damage in COVID-19 is caused by the immune system. The high amounts of CRP could have an additional influence on blood pressure in severe COVID-19.

An aberrant STAT pathway is central to COVID-19

COVID-19 is caused by SARS-CoV-2 infection and characterized by diverse clinical symptoms. Type I interferon (IFN-I) production is impaired and severe cases lead to ARDS and widespread coagulopathy. We propose that COVID-19 pathophysiology is initiated by SARS-CoV-2 gene products, the NSP1 and ORF6 proteins, leading to a catastrophic cascade of failures. These viral components induce signal transducer and activator of transcription 1 (STAT1) dysfunction and compensatory hyperactivation of STAT3. In SARS-CoV-2-infected cells, a positive feedback loop established between STAT3 and plasminogen activator inhibitor-1 (PAI-1) may lead to an escalating cycle of activation in common with the interdependent signaling networks affected in COVID-19. Specifically, PAI-1 upregulation leads to coagulopathy characterized by intravascular thrombi. Overproduced PAI-1 binds to TLR4 on macrophages, inducing the secretion of proinflammatory cytokines and chemokines. The recruitment and subsequent activation of innate immune cells within an infected lung drives the destruction of lung architecture, which leads to the infection of regional endothelial cells and produces a hypoxic environment that further stimulates PAI-1 production. Acute lung injury also activates EGFR and leads to the phosphorylation of STAT3. COVID-19 patients' autopsies frequently exhibit diffuse alveolar damage (DAD) and increased hyaluronan (HA) production which also leads to higher levels of PAI-1. COVID-19 risk factors are consistent with this scenario, as PAI-1 levels are increased in hypertension, obesity, diabetes, cardiovascular diseases, and old age. We discuss the possibility of using various approved drugs, or drugs currently in clinical development, to treat COVID-19. This perspective suggests to enhance STAT1 activity and/or inhibit STAT3 functions for COVID-19 treatment. This might derail the escalating STAT3/PAI-1 cycle central to COVID-19.

Selective Apheresis of C-Reactive Protein for Treatment of Indications with Elevated CRP Concentrations

Almost every kind of inflammation in the human body is accompanied by rising C-reactive protein (CRP) concentrations. This can include bacterial and viral infection, chronic inflammation and so-called sterile inflammation triggered by (internal) acute tissue injury. CRP is part of the ancient humoral immune response and secreted into the circulation by the liver upon respective stimuli. Its main immunological functions are the opsonization of biological particles (bacteria and dead or dying cells) for their clearance by macrophages and the activation of the classical complement pathway. This not only helps to eliminate pathogens and dead cells, which is very useful in any case, but unfortunately also to remove only slightly damaged or inactive human cells that may potentially regenerate with more CRP-free time. CRP action severely aggravates the extent of tissue damage during the acute phase response after an acute injury and therefore negatively affects clinical outcome. CRP is therefore a promising therapeutic target to rescue energy-deprived tissue either caused by ischemic injury (e.g., myocardial infarction and stroke) or by an overcompensating immune reaction occurring in acute inflammation (e.g., pancreatitis) or systemic inflammatory response syndrome (SIRS; e.g., after transplantation or surgery). Selective CRP apheresis can remove circulating CRP safely and efficiently. We explain the pathophysiological reasoning behind therapeutic CRP apheresis and summarize the broad span of indications in which its application could be beneficial with a focus on ischemic stroke as well as the results of this therapeutic approach after myocardial infarction.