In-silico evaluation of natural alkaloids against the main protease and spike glycoprotein as potential therapeutic agents for SARS-CoV-2

Severe Acute Respiratory Syndrome Corona Virus (SARS-CoV-2) is the causative agent of COVID-19 pandemic, which has resulted in global fatalities since late December 2019. Alkaloids play a significant role in drug design for various antiviral diseases, which makes them viable candidates for treating COVID-19. To identify potential antiviral agents, 102 known alkaloids were subjected to docking studies against the two key targets of SARS-CoV-2, namely the spike glycoprotein and main protease. The spike glycoprotein is vital for mediating viral entry into host cells, and main protease plays a crucial role in viral replication; therefore, they serve as compelling targets for therapeutic intervention in combating the disease. From the selection of alkaloids, the top 6 dual inhibitory compounds, namely liensinine, neferine, isoliensinine, fangchinoline, emetine, and acrimarine F, emerged as lead compounds with favorable docked scores. Interestingly, most of them shared the bisbenzylisoquinoline alkaloid framework and belong to Nelumbo nucifera, commonly known as the lotus plant. Docking analysis was conducted by considering the key active site residues of the selected proteins. The stability of the top three ligands with the receptor proteins was further validated through dynamic simulation analysis. The leads underwent ADMET profiling, bioactivity score analysis, and evaluation of drug-likeness and physicochemical properties. Neferine demonstrated a particularly strong affinity for binding, with a docking score of -7.5025 kcal/mol for main protease and -10.0245 kcal/mol for spike glycoprotein, and therefore a strong interaction with both target proteins. Of the lead alkaloids, emetine and fangchinoline demonstrated the lowest toxicity and high LD50 values. These top alkaloids, may support the body's defense and reduce the symptoms by their numerous biological potentials, even though some properties naturally point to their direct antiviral nature. These findings demonstrate the promising anti-COVID-19 properties of the six selected alkaloids, making them potential candidates for drug design. This study will be beneficial in effective drug discovery and design against COVID-19 with negligible side effects.

POS1495-HPR COVID-19, INFLUENZA AND PNEUMOCOCCUS VACCINATION UPTAKE IN PATIENTS WITH RHEUMATIC DISEASE: A PROSPECTIVE AUDIT

Background

Patients with autoimmune inflammatory rheumatic diseases are susceptible to infections. This could be attributed to theimmunosuppressive effect of the underlying condition or the use of immunomodulatory medications. According to the Department of Health guidelines inthe UK and the European League Against Rheumatism (EULAR), patients who are immunosuppressed should be vaccinated against influenza and pneumococcal infection, as well as COVID-19 infection.

Objectives

Our aim was to explore the Pneumococcal, Influenza and COVID-19 vaccination uptake of our patients with different autoimmune inflammatory rheumatological conditions. In addition, to assess the side effects profile and the status of their underlying rheumatological diseases following COVID-19 vaccination.

Methods

We undertook a prospective audit of consecutive patients with regards to their vaccination update for influenza, pneumococcus, and COVID-19, utilizing a standard questionnaire and compared the results to our 2017 data.

Results

Some 81% of patients received the influenza vaccination (compared to 47% in 2017) representing a 172% improvement, p<0.001. Some 53% received the pneumococcus vaccination compared to 28% in 2017, indicating a 185% improvement, p=0.003. With regards to COVID-19 vaccination, 98/101(97%) of eligible patients received at least one dose and 66% received two doses. 47% received Astra Zeneca, 52% Pfizer and 1% unsure. 46% of patients mentioned, no one specifically discussed the COVID vaccine with them - got information via SMS/ from media, However, 37% of patients were informed by GP Doctor/ Nurse, 14% from the person giving the vaccine, and 7% from specialist hospital doctor. Safety concerns were indicated by all 3 patients who deferred vaccination.

Most side-effects were observed following the first dose (74 patients) vs. the second dose (13 patients) and were mainly mild (66%), but also moderate (19%) and severe (15%). The sore arm was the commonest side-effect, whilst the majority of side-effects resolved within two days. Crucially, 28% reported a flare of the rheumatological condition following the vaccination. No patients receiving at least one dose were diagnosed with COVID-19 infection subsequently.

Conclusion

Vaccination rates for influenza and pneumococcus have improved substantially since 2017, although the population with rheumatic diseases still has low uptake in pneumococcal vaccination. The COVID-19 vaccination uptake has been extremely high in this cohort.

Disclosure of Interests

None declared

Alpha 1-antichymotrypsin inhibits A beta degradation in vitro and in vivo

The neuropathology of Alzheimer's disease (AD) is characterized by extensive deposition of the toxic amyloid beta peptide (A beta) in selected regions of the brain and brain vasculature (Selkoe, 1999). Thus, lowering the levels of A beta may be beneficial for AD patients. A beta is a proteolytic fragment derived from the amyloid precursor protein (APP). The mechanisms of A beta formation from its precursor have been studied extensively; however, considerably less effort has been invested into studying A beta clearance. We find that the degradation of A beta in our system is dependent upon the presence of a metallopeptidase E.C.3.4.24.15 (MP24.15) (Yamin et al., 1999). We have previously purified MP24.15 to homogeneity from AD brain and identified it as an APP-processing protease in vitro (Papastoitsis, 1994). To confirm its role in cell culture, we transfected SKNMC neuroblastoma cells with sense and antisense cDNAs of MP24.15 and with a mock construct. Compared to mock conditioned media (CM), CM of MP24.15-overexpressing cells had very high A beta-degrading activity. Conversely, CM of antisense-expressing cells lacked A beta-degrading activity. These results suggested that MP24.15 is involved in A beta degradation. Characterization of the proteolytic activity directly responsible for A beta degradation using a spectrum of protease inhibitors revealed that only serine protease inhibitors completely blocked A beta degradation. Therefore, MP24.15 appears to activate a serine protease, which then cleaves A beta. Interestingly, alpha 1-antichymotrypsin (ACT) which we discovered to be highly elevated in AD brain (Abraham, et al., 1988) also inhibited A beta degradation. To our delight, ACT proved to be an inhibitor of A beta degradation in vivo as well. When we crossed transgenic mice expressing human ACT with plaque-producing mice expressing human APP, the doubly transgenic mice had twice as many plaques at 20 months of age as the APP mice (Mucke et al., 2000). Successful completion of this study could lead to the design of reagents that would reduce the amyloid load in AD patients.

Metalloendopeptidase EC 3.4.24.15 is necessary for Alzheimer's amyloid-beta peptide degradation

We have investigated the functional relationship between metalloendopeptidase EC 3.4.24.15 (MP24.15) and the amyloid precursor protein involved in Alzheimer's disease (AD) and discovered that the enzyme promotes Abeta degradation. We show here that conditioned medium (CM) of MP24.15 antisense-transfected SKNMC neuroblastoma has significantly higher levels of Abeta. Furthermore, synthetic-Abeta degradation was increased or decreased following incubation with CM of sense or antisense-transfected cells, respectively. Soluble Abeta1-42 was degraded more slowly than soluble Abeta1-40, while aggregated Abeta1-42 showed almost no degradation. Pretreatment of CM with serine proteinase inhibitors 4-(2-aminoethyl)benzenesulfonyl fluoride and diisopropyl fluorophosphate completely inhibited Abeta degradation. Additionally, alpha1-antichymotrypsin (ACT), a serpin family inhibitor tightly associated with plaques and elevated in AD brain, blocked up to 60% of Abeta degradation. Interestingly, incubation of CM of MP24. 15-overexpressing cells with ACT formed an SDS-resistant ACT complex, suggesting an ACT-serine proteinase interaction. Recombinant MP24. 15 alone did not degrade Abeta. 14C-Diisopropyl fluorophosphate-radiolabeled CM from MP24.15-overexpressing cells contained increased levels of several active serine proteinases, suggesting that MP24.15 activates one or more Abeta-degrading serine proteases. Thus, ACT may cause Abeta accumulation by inhibiting an Abeta-degrading enzyme or by direct binding to Abeta, rendering it degradation-resistant. Identification of the Abeta-degrading enzyme and MP24.15's role in its activation is underway. Pharmacological modulation of either enzyme may provide a means of regulating Abeta in the brain.

Interleukin-1 beta-modulated gene expression in immortalized human chondrocytes

Immortalized human chondrocytes were established by transfection of primary cultures of juvenile costal chondrocytes with vectors encoding simian virus 40 large T antigen and selection in suspension culture over agarose. Stable cell lines were generated that exhibited chondrocyte morphology, continuous proliferative capacity (> 80 passages) in monolayer culture in serum-containing medium, and expression of mRNAs encoding chondrocyte-specific collagens II, IX, and XI and proteoglycans in an insulin-containing serum substitute. They did not express type X collagen or versican mRNA. These cells synthesized and secreted extracellular matrix molecules that were reactive with monoclonal antibodies against type II collagen, large proteoglycan (PG-H, aggrecan), and chondroitin-4- and chondroitin-6-sulfate. Interleukin-1 beta (IL-1 beta) decreased the levels of type II collagen mRNA and increased the levels of mRNAs for collagenase, stromelysin, and immediate early genes (egr-1, c-fos, c-jun, and jun-B). These cell lines also expressed reporter gene constructs containing regulatory sequences (-577/+3,428 bp) of the type II collagen gene (COL2A1) in transient transfection experiments, and IL-1 beta suppressed this expression by 50-80%. These results show that immortalized human chondrocytes displaying cartilage-specific modulation by IL-1 beta can be used as a model for studying normal and pathological repair mechanisms.

Human endothelial actin-binding protein (ABP-280, nonmuscle filamin): a molecular leaf spring

Actin-binding protein (ABP-280, nonmuscle filamin) is a ubiquitous dimeric actin cross-linking phosphoprotein of peripheral cytoplasm, where it promotes orthogonal branching of actin filaments and links actin filaments to membrane glycoproteins. The complete nucleotide sequence of human endothelial cell ABP cDNA predicts a polypeptide subunit chain of 2,647 amino acids, corresponding to 280 kD, also the mass derived from physical measurements of the native protein. The actin-binding domain is near the amino-terminus of the subunit where the amino acid sequence is similar to other actin filament binding proteins, including alpha-actinin, beta-spectrin, dystrophin, and Dictyostelium abp-120. The remaining 90% of the sequence comprises 24 repeats, each approximately 96 residues long, predicted to have stretches of beta-sheet secondary structure interspersed with turns. The first 15 repeats may have substantial intrachain hydrophobic interactions and overlap in a staggered fashion to yield a backbone with mechanical resilience. Sequence insertions immediately before repeats 16 and 24 predict two hinges in the molecule near points where rotary-shadowed molecules appear to swivel in electron micrographs. Both putative hinge regions are susceptible to cleavage by proteases and the second also contains the site that binds the platelet glycoprotein Ib/IX complex. Phosphorylation consensus sequences are also located in the hinges or near them. Degeneracy within every even-numbered repeat between 16 and 24 and the insertion before repeat 24 may convert interactions within chains to interactions between chains to account for dimer formation within a domain of 7 kD at the carboxy-terminus. The structure of ABP dimers resembles a leaf spring. Interchain interactions hold the leaves firmly together at one end, whereas intrachain hydrophobic bonds reinforce the arms of the spring where the leaves diverge, making it sufficiently stiff to promote high-angle branching of actin filaments. The large size of the leaves, their interruption by two hinges and flexible actin-binding site, facilitate cross-linking of widely dispersed actin filaments.