Drugs for the prevention and treatment of COVID-19 and its complications: An update on what we learned in the past 2 years.

The COVID-19 Committee of the Lincei Academy has reviewed the scientific evidence supporting the efficacy and safety of existing and new drugs/biologics for the preventing and treating of COVID-19 and its complications. This position paper reports what we have learned in the field in the past 2 years. The focus was on, but not limited to, drugs and neutralizing monoclonal antibodies, anti-SARS-CoV-2 agents, anti-inflammatory and immunomodulatory drugs, complement inhibitors and anticoagulant agents. We also discuss the risks/benefit of using cell therapies on COVID-19 patients. The report summarizes the available evidence, which supports recommendations from health authorities and panels of experts regarding some drugs and biologics, and highlights drugs that are not recommended, or drugs for which there is insufficient evidence to recommend for or against their use. We also address the issue of the safety of drugs used to treat underlying concomitant conditions in COVID-19 patients. The investigators did an enormous amount of work very quickly to understand better the nature and pathophysiology of COVID-19. This expedited the development and repurposing of safe and effective therapeutic interventions, saving an impressive number of lives in the community as well as in hospitals.

Efficacy of certolizumab pegol in naïve versus multi-treated patients affected by psoriatic arthritis.

BACKGROUND: The efficacy and safety of certolizumab pegol over 52 weeks was compared in two groups of patients: Group 1 comprised patients naïve to biologic treatments; Group 2 comprised patients previously treated with one or more antitumor necrosis factor (TNF)-α and/or anti-interleukin (IL) agents. METHODS: We reported results in 50 patients affected by both mild psoriasis (PsO) and psoriatic arthritis (PsA). Primary endpoint was a reduction from baseline at week 52 of Disease Activity Score (DAS44-ESR) in both groups of patients. Secondary endpoints were a reduction from baseline at week 52 of Psoriasis Area Severity Index (PASI), Visual Analog Scale for Pain (PAIN VAS), ESR, CRP, and Dermatology Life Quality Index (DLQI). RESULTS: We observed a statistically significant improvement of both cutaneous and rheumatic disease in all patients, with a consistent reduction of DAS44-ESR, PASI, and PAIN VAS from baseline to week 52. DAS44-ESR decreased from 3.9 at BL to 1.5 at W52 (Group 1), and from 3.8 to 1.7 at W52 (Group 2). Mean PASI Score decreased from 3.2 at baseline (BL) to 0.4 at W52 (Group 1), and from 5.4 to 0.7 at W52 (Group 2). Mean PAIN-VAS decreased from a value of 73.5 at BL to 2.5 at W52 (Group 1), and from a value of 62.4 at BL to 9.2 at W52 (Group 2). We also found a reduction in ESR, CRP and DLQI values for each time point. CONCLUSIONS: Our results confirm that CZP can be administered safely and effectively to treat both psoriasis and psoriatic arthritis irrespective of previous treatments with biologic agents.

Characterization of transglutaminase type II role in dendritic cell differentiation and function.

DCs play an essential role in the endotoxic shock, and their profound depletion occurs in septic patients and septic mice. TG2(-/-) mice are more resistant to the endotoxic shock induced by LPS. Here, we studied the cellular and molecular basis of this effect, analyzing the role of the enzyme in DC maturation and function. We show that TG2 is up-regulated drastically during the final, functional maturation of DCs consequent to LPS treatment. In keeping with this finding, the inhibition of the enzyme cross-linking activity determines the impairment of DC function highlighted by wide phenotypic changes associated with a reduced production of cytokines (IL-10, IL-12) after LPS treatment and a lower ability to induce IFN-gamma production by naïve T cells. The in vivo analysis of DCs obtained from TG2(-/-) mice confirmed that the enzyme ablation leads to an impairment of DC maturation and their reduced responsiveness to LPS treatment. In fact, a marked decrease in DC death, TLR4 down-regulation, and impaired up-regulation of MHCII and CD86 were observed in TG2(-/-) mice. Taken together, these data suggest that TG2 plays an important role in regulating the response of DCs to LPS and could be a candidate target for treating endotoxin-induced sepsis.

Transglutaminase 2 is involved in autophagosome maturation.

Autophagy is a highly conserved cellular process responsible for the degradation of long-lived proteins and organelles. Autophagy occurs at low levels under normal conditions, but it is enhanced in response to stress, e.g. nutrient deprivation, hypoxia, mitochondrial dysfunction and infection. "Tissue" transglutaminase (TG2) accumulates, both in vivo and in vitro, to high levels in cells under stressful conditions. Therefore, in this study, we investigated whether TG2 could also play a role in the autophagic process. To this end, we used TG2 knockout mice and cell lines in which the enzyme was either absent or overexpressed. The ablation of TG2 protein both in vivo and in vitro, resulted in an evident accumulation of microtubule-associated protein 1 light chain 3 cleaved isoform II (LC3 II) on pre-autophagic vesicles, suggesting a marked induction of autophagy. By contrast, the formation of the acidic vesicular organelles in the same cells was very limited, indicating an impairment of the final maturation of autophagolysosomes. In fact, the treatment of TG2 proficient cells with NH4Cl, to inhibit lysosomal activity, led to a marked accumulation of LC3 II and damaged mitochondria similar to what we observed in TG2-deficient cells. These data indicate a role for TG2-mediated post-translational modifications of proteins in the maturation of autophagosomes accompanied by the accumulation of many damaged mitochondria.

Transglutaminase 2 ablation leads to defective function of mitochondrial respiratory complex I affecting neuronal vulnerability in experimental models of extrapyramidal disorders.

Transglutaminase 2 (TG2) represents the most ubiquitous isoform belonging to the TG family, and has been implicated in the pathophysiology of basal ganglia disorders, such as Parkinson's disease and Huntington's disease. We show that ablation of TG2 in knockout mice causes a reduced activity of mitochondrial complex I associated with an increased activity of complex II in the whole forebrain and striatum. Interestingly, TG2-/- mice were protected against nigrostriatal damage induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, which is converted in vivo into the mitochondrial complex I inhibitor, 1-methyl-4-phenyl-pyridinium ion. In contrast, TG2-/- mice were more vulnerable to nigrostriatal damage induced by methamphetamine or by the complex II inhibitor, 3-nitropropionic acid. Proteomic analysis showed that proteins involved in the mitochondrial respiratory chain, such as prohibitin and the beta-chain of ATP synthase, are substrates for TG2. These data suggest that TG2 is involved in the regulation of the respiratory chain both in physiology and pathology, contributing to set the threshold for neuronal damage in extrapyramidal disorders.

"Tissue" transglutaminase contributes to the formation of disulphide bridges in proteins of mitochondrial respiratory complexes.

In this study we provide the first in vivo evidences showing that, under physiological conditions, "tissue" transglutaminase (TG2) might acts as a protein disulphide isomerase (PDI) and through this activity contributes to the correct assembly of the respiratory chain complexes. Mice lacking TG2 exhibit mitochondrial energy production impairment, evidenced by decreased ATP levels after physical challenge. This defect is phenotypically reflected in a dramatic decrease of motor behaviour of the animals. We propose that the molecular mechanism, underlying such a phenotype, resides in a defective disulphide bonds formation in ATP synthase (complex V), NADH-ubiquinone oxidoreductase (complex I), succinate-ubiquinone oxidoreductase (complex II) and cytochrome c oxidase (complex IV). In addition, TG2-PDI might control the respiratory chain by modulating the formation of the prohibitin complexes. These data elucidate a new pathway that directly links the TG2-PDI enzymatic activity with the regulation of mitochondrial respiratory chain function.

Transglutaminase type II is a key element in the regulation of the anti-inflammatory response elicited by apoptotic cell engulfment.

A key feature of the macrophage-dependent clearance of apoptotic cells is the down-regulation of proinflammatory cytokines. Deficiency in the phagocytosis of apoptotic cells is often associated with the development of inflammatory reactions, resulting in chronic inflammatory and autoimmune diseases. The molecular mechanisms that regulate the engulfment process and particularly the immunomodulatory factors involved are still largely unknown in mammals. We have previously reported that the ablation of transglutaminase type II (TG2) in mice results in the defective clearance of apoptotic cells associated with the development of splenomegaly, autoantibodies, and glomerulonephritis. In this study we have investigated the mechanisms at the basis of the development of inflammation/autoimmunity associated with the defective clearance of apoptotic cells characterizing TG2 knockout mice. To this aim we compared the macrophage response to apoptotic cell exposure in wild-type vs TG2-null mice. We demonstrated that the lack of TG2 results in an impaired capacity of macrophages to engulf, but not to bind, apoptotic cells, which is paralleled by an abnormal inflammatory response both in vivo and in vitro. We have identified a differential response in the release of several cytokines in TG2(-/-) vs wild-type mice. Particularly relevant is the finding that both TGF-beta and IL-12 regulations were significantly altered in the absence of TG2. These results help explain the autoimmune phenotype developed by these mice and suggest that TG2 is a key regulatory element of the anti-inflammatory features of apoptosis.