Inflammatory Response and Activation of Coagulation after COVID-19 Infection.

SARS-CoV-2 (COVID-19) infection is responsible for causing a disease with a wide spectrum of clinical presentations. Predisposition to thromboembolic disease due to excessive inflammation is also attributed to the disease. The objective of this study was to characterize the clinical and laboratory aspects of hospitalized patients, in addition to studying the pattern of serum cytokines, and associate them with the occurrence of thromboembolic events. METHODOLOGY: A retrospective cohort study with 97 COVID-19 patients hospitalized from April to August 2020 in the Triângulo Mineiro macro-region was carried out. A review of medical records was conducted to evaluate the clinical and laboratory aspects and the frequency of thrombosis, as well as the measurement of cytokines, in the groups that presented or did not present a thrombotic event. RESULTS: There were seven confirmed cases of thrombotic occurrence in the cohort. A reduction in the time of prothrombin activity was observed in the group with thrombosis. Further, 27.8% of all patients had thrombocytopenia. In the group that had thrombotic events, the levels of IL1b, IL-10, and IL2 were higher (p < 0.05). CONCLUSIONS: In the studied sample, there was an increase in the inflammatory response in patients with thrombotic events, confirmed by the increase in cytokines. Furthermore, in this cohort, a link was observed between the IL-10 percentage and an increased chance of a thrombotic event.

Clinical-Epidemiology Aspect of Inpatients With Moderate or Severe COVID-19 in a Brazilian Macroregion: Disease and Countermeasures.

COVID-19, also known as coronavirus disease 2019, is an infectious viral disease caused by SARS-CoV-2, a novel coronavirus. Since its emergence, its epidemiology has been explored; however, for some regions of the world, COVID-19's behavior, incidence, and impact remain unclear. In continental nations like Brazil, this lack of knowledge results in nonuniform control, prevention, and treatment measures, which can be controversial in some locations. This study aimed to describe the epidemiological profile of patients with COVID-19 in the macroregion of Triângulo Sul in the state of Minas Gerais (MG), Brazil. Between March 25 and October 21, 2020, data were collected and statistically analyzed from 395 hospitalized patients in the city of Uberaba, MG, suspected to have moderate or severe forms of the disease. Of the 395 suspected cases, 82% were confirmed to be positive for COVID-19. The mean age of positive patients was 58.4 years, and 60.76% were male. Following these patients throughout their hospitalization, a mortality rate of 31.3% was observed. In the population positive for COVID-19, the risk of death increased by 4% for each year of the patient's age. Likewise, the older the patient, the longer their hospitalization and the higher the risk of developing acute respiratory failure. Among the treatments tested in patients, heparin was associated with protection against mortality, and the absence of anticoagulant use was linked to a more than six times greater risk of death. Finally, comorbidities in patients with COVID-19 were positively correlated with increased hospitalization time. In summary, this study revealed that age, presence of comorbidities, length of hospitalization, and drug treatment considerably altered COVID-19's lethality. To understand infection rates and the factors involved in COVID-19's lethality, knowledge of the local epidemiology is necessary.

T Lymphocyte Exhaustion During Human and Experimental Visceral Leishmaniasis.

A key point of immunity against protozoan Leishmania parasites is the development of an optimal T cell response, which includes a low apoptotic rate, high proliferative activity and polyfunctionality. During acute infection, antigen-specific T cells recognize the pathogen resulting in pathogen control but not elimination, promoting the development and the maintenance of a population of circulating effector cells that mount rapid response quickly after re-exposure to the parasite. However, in the case of visceral disease, the functionality of specific T cells is lost during chronic infection, resulting in inferior effector functions, poor response to specific restimulation, and suboptimal homeostatic proliferation, a term referred to as T cell exhaustion. Multiple factors, including parasite load, infection duration and host immunity, affect T lymphocyte exhaustion. These factors contribute to antigen persistence by promoting inhibitory receptor expression and sustained production of soluble mediators, influencing suppressive cell function and the release of endogenous molecules into chronically inflamed tissue. Together, these signals encourage several changes, reprogramming cells into a quiescent state, which reflects disease progression to more severe forms, and development of acquired resistance to conventional drugs to treat the disease. These points are discussed in this review.

Exploring the carbohydrate-binding ability of Canavalia bonariensis lectin in inflammation models.

Lectins are a group of proteins of non-immune origin recognized for their ability to bind reversibly to carbohydrates. Researchers have been intrigued by oligosaccharides and glycoconjugates for their involvement as mediators of complex cellular events and then many biotechnological applications of lectins are based on glycocode decoding and their activities. Here, we report a structural and biological study of a ConA-like mannose/glucose-specific lectin from Canavalia bonariensis seeds, CaBo. More specifically, we evaluate the binding of CaBo with α-methyl-D-mannoside (MMA) and mannose-1,3-α-D-mannose (M13) and the resultant in vivo effects on a rat model of acute inflammation. A virtual screening was also carried out to cover a larger number of possible bindings of CaBo. In silico analysis demonstrated the stability of CaBo interaction with mannose-type ligands, and the lectin was able to induce acute inflammation in rats with the participation of the carbohydrate recognition domain (CRD) and histamine release. These results confirm the ability of CaBo to interact with hybrid and high-mannose N-glycans, supporting the hypothesis that CaBo's biological activity occurs primarily through its interaction with cell surface glycosylated receptors.

Per oral rat treatment with glyconjugate fractions of Genipa americana leaves protects thrombus formation.

: The current study evaluated the effect of the arabinogalactan-glycoconjugate fractions (FI and FII) isolated from Genipa americana leaves given per oral in rat hemostasis protocols. Rats received daily treatment with FI or FII during 7 days and were evaluated for coagulation, platelet aggregation, venous thrombosis and bleeding tendency 1 h after the last treatment. FII prolonged in 5.5-fold the rat plasma coagulation time (activated partial thromboplastin time test). FI inhibited by 46% the platelet aggregation. Both FI and FII prevented thrombus formation by 33 and 28%, respectively. However, the bleeding time was not altered by any fractions, showing an advantage in relation to acetylsalicylic acid or warfarin that increased the bleeding time in 3.6 and 2.9-fold, respectively. Per oral treatment with the arabinogalactan-glyconjugate fractions FI and FII of G. americana leaves in rats prevents thrombus formation, being devoid of hemorrhagic risk. These results bring novel therapeutic possibilities for thromboembolic diseases.

An arabinogalactan-glycoconjugate from Genipa americana leaves present anticoagulant, antiplatelet and antithrombotic effects.

Glycoconjugates extracted from Genipa americana leaves (PE-Ga) were separated into two fractions, denominated as PFI and PFII (total carbohydrate: 23-36%/uronic acid: 9-30%; protein:4-5%; polyphenols:0.776-0.812 mg/g), mainly composed by arabinose, galactose and uronic acid and presenting high (PFI) and low (PFII) molecular weight (based on polyacrylamide electrophoresis gel and gel permeation chromatography). Uronic acid was also detected by FT-IR (wavenumbers: 1410 and 1333 cm-1) and NMR (α-GalpA). Deproteinization of glycoconjugates showed reduced protein and polyphenol levels with loss of its biological effects. PE-Ga and PFII prolonged clotting time-aPTT (3.6 and 1.8x), while PE-Ga and PFI inhibited by 48% (100 µg/µL) the ADP-induced platelet aggregation. In vivo, these glycoconjugates at 1 mg/kg inhibited (37-53%) venous thrombus formation (4.7 ± 0.1 mg) and increased bleeding time (PE-Ga and PFI:3.0x; PFII:1.7x vs. PBS:906 ± 16.7 s). In conclusion, the arabinogalactan-rich glycoconjugate of G. americana leaves, containing uronic acid, present antiplatelet, anticoagulant (intrinsic/common pathway) and antithrombotic effects, with low hemorrhagic risk.

Purification and molecular characterization of a novel mannose-specific lectin from Dioclea reflexa hook seeds with inflammatory activity.

A novel lectin present in Dioclea reflexa seeds (DrfL) was discovered and described in this study. DrfL was purified in a single step by affinity chromatography in a Sephadex G-50 column. The lectin strongly agglutinated rabbit erythrocytes and was inhibited by α-methyl-D-mannoside, D-mannose, and D-glucose. The hemagglutinating activity of DrfL is optimum at pH 5.0-7.0, stable up to 50 °C, and dependent on divalent cations. Similar to other lectins of the subtribe Diocleinae, the analysis by mass spectrometry indicated that DrfL has three chains (α, ß, and γ) with masses of 25,562, 12,874, and 12,706 Da, respectively, with no disulfide bonds or glycosylation. DrfL showed inflammatory activity in the paw edema model and exhibited low cytotoxicity against Artemia sp.

Purified polysaccharides of Geoffroea spinosa barks have anticoagulant and antithrombotic activities devoid of hemorrhagic risks.

Polysaccharides were extracted from the barks of Geoffroea spinosa, purified using anion exchange chromatography and characterized by chemical and methylation analysis, complemented by infrared and NMR spectroscopies. These polysaccharides were tested for their anticoagulant, antithrombotic and antiplatelet activities and also for their effects on bleeding. Unfractionated polysaccharide contains low levels of protein and high levels of carbohydrate (including hexuronic acid). The purified polysaccharides (fractions FII and FIII) are composed of arabinose (Ara), rhamnose (Rha), hexuronic acid, small amounts of galactose, but no sulfate ester. They have highly complex structure, which was partially characterized. NMR and methylation analysis indicate that the polysaccharides have a core of α-Rhap and branches of 5-linked α-Araf. Residues of 4-linked α-GalpA are also found in the structure. The unfractionated (TPL) and fraction FIII, but not fractions FI and FII, prolonged the activated partial thromboplastin time (aPTT). TPL, FII and FIII inhibited the platelet aggregation induced by ADP. More significantly, both unfractionated and purified fractions exhibited potent antithrombotic effect (31-60%) and the fractions did not modify the bleeding tendency. These plant polysaccharides could be alternative source of new anticoagulant, antiplatelet and antithrombotic compounds devoid of the undesirable risk of hemorrhage.