Recent advances on smart glycoconjugate vaccines in infections and cancer

Vaccination is one of the greatest achievements in biomedical research preventing death and morbidity in many infectious diseases through the induction of pathogen-specific humoral and cellular immune responses. Currently, no effective vaccines are available for pathogens with a highly variable antigenic load, such as the human immunodeficiency virus or to induce cellular T-cell immunity in the fight against cancer. The recent SARS-CoV-2 outbreak has reinforced the relevance of designing smart therapeutic vaccine modalities to ensure public health. Indeed, academic and private companies have ongoing joint efforts to develop novel vaccine prototypes for this virus. Many pathogens are covered by a dense glycan-coat, which form an attractive target for vaccine development. Moreover, many tumor types are characterized by altered glycosylation profiles that are known as “tumor-associated carbohydrate antigens”. Unfortunately, glycans do not provoke a vigorous immune response and generally serve as T-cell-independent antigens, not eliciting protective immunoglobulin G responses nor inducing immunological memory. A close and continuous crosstalk between glycochemists and glycoimmunologists is essential for the successful development of efficient immune modulators. It is clear that this is a key point for the discovery of novel approaches, which could significantly improve our understanding of the immune system. In this review, we discuss the latest advancements in development of vaccines against glycan epitopes to gain selective immune responses and to provide an overview on the role of different immunogenic constructs in improving glycovaccine efficacy

The influence of glycerol as a carbon source and ph of cultivation medium on biosynthesis of cell wall polymers of candida utilis and kluyveromyces fragilis yeasts

Celem badań było określenie możliwości wykorzystania glicerolu w hodowli drożdży Candida utilis oraz Kluyveromyces fragilis ukierunkowanej na biosyntezę β-glukanu i/lub mannoprotein tworzących strukturę ściany komórkowej tych grzybów. Preparaty ścian uzyskiwano na drodze autolizy komórek drożdży. Poddawano je następnie frakcjonowaniu w warunkach alkalicznych na poszczególne polisacharydy. Stwierdzono zróżnicowanie zawartości β(1,3)-/β(1,6)-glukanów i mannoprotein w ścianach badanych drożdży, zależne od szczepu, stężenia glicerolu oraz pH podłoży hodowlanych. Istotne zwiększenie zawartości cukrów ogółem i β(1,3)-/β(1,6)-glukanów w ścianie drożdży Candida utilis ATTC 9950 odnotowano po hodowli w podłożu o pH 4,0 zawierającym 2% glicerolu. W preparatach ścian omawianego szczepu stwierdzono wówczas około 75% cukrów ogółem i około 53% β(1,3)-/(1,6)-glukanu. Drożdże Kluyveromyces fragilis R11 okazały się lepszym źródłem mannoprotein. W preparatach komórek z podłoży o pH 7, zawierających 3 lub 5% glicerolu, odnotowano około 30,5% tych polimerów.The structure of yeast cell wall is mainly composed of polymers such as β-glucans and α-mannan (present as mannoprotein). It is well known that yeast β-glucans and mannoprotein exhibit a range of bioactive properties in humans and animals, like anti-toxic, anti-mutagenic, anticancerous and anti-oxidative activity, stimulation of immunological response as well as antibacterial properties. The content of β-glucans and mannoprotein in cell wall of unicellular fungi is connected to growth conditions. This work reports on the infl uence of glycerol as a carbon source and pH of the medium on structural cell wall polymers (β-glucan and mannoprotein) biosynthesis of Candida utilis ATTC 9950 and Kluyveromyces fragilis R11. The experimental cultivations of investigated yeast strains were performed in control YPD medium and in a model mediums where glucose was replaced with glycerol in the amount of 2, 3 and 5% (w/v). All mediums were prepared in three pH variants i.e. 4.0, 5.0 and 7.0. The preparations of cell walls of yeasts from the experimental cultivations were achieved via 24-h cell autolysis. The obtained cell wall preparations were subjected to fractionation on particular structural polysaccharides, i.e. β(1,3)-glucan, β(1,6)-glucan and mannoproteiny, by extraction in alkaline conditions. The content of reducing carbohydrates (as glucose) was analyzed using colorimetric method (λ = 540 nm) with 3,5-dinitrosalicylic acid after hydrolysis of particular fractions in acidic conditions. Results of the investigation demonstrated that cultivation of Candida utilis ATTC 9950 and Kluyveromyces fragilis R11 on glicerol, low-cost substrates from biodiesel production, may intensify the biosynthesis of cell wall polymers. The tendency depended on cultivation medium and strain. For yeast of genus Candida the portion of polysaccharides in total, as well as β(1,3)/(1,6)-glucan content were highest after cultivation on medium containing 2% of glycerol and pH 4.0. It was 75% and 53% respectively. Depending on growth conditions, the Candida utilis ATTC 9950 strain contained from 2 to 4 times more β(1,3)/(1,6)-glucan in cell wall structure comparing with Kluyveromyces fragilis yeasts. At the same time, Kluyveromyces fragilis R11 strain was more effi cient source of mannoprotein comparing with Candida yeast. Preparations of cell walls of Kluyveromyces fragilis after yeast cultivation in mediums with 3 and 5% of glycerol pH 7.0 contained app. 30.5% of mannoproteins. The results confi rmed that cultivation in medium with glycerol as a carbon source contributed to obtaining the biomass of Candida utilis and Kluyveromyces fragilis with increased portion of functional cell wall polymers. Further studies should be oriented towards an optimization of cultivation conditions for effi cient biosynthesis of β-glucans or mannoprotein and to establish their functional properties

Evaluation of the ability of the intraclellular fat biosynthesis by Rhodotorula gracilis yeast in media containing potato wastewater enriched with glycerol

Celem badań było określenie zdolności wzrostu drożdży Rhodotorula gracilis i biosyntezy przez nie wewnątrzkomórkowego tłuszczu (SCO – Single Cell Oil) podczas 72-godzinnej hodowli wgłębnej w podłożach zawierających ziemniaczaną odpadową wodę sokową wzbogaconą glicerolem w ilościach 5, 10, 15 i 20% obj. Największy plon biomasy komórkowej (28,65 gs.s.·dm⁻³) uzyskano w podłożu zawierającym 5% obj. glicerolu, a najwięcej wewnątrzkomórkowego tłuszczu (25,57 g·100 gs.s.⁻¹) stwierdzono w biomasie drożdży rosnących w podłożach zawierających 20% obj. glicerolu. Ta ilość tłuszczu była 3 i 5 razy większa w porównaniu z eksperymentami prowadzonymi w podłożu kontrolnym YPD (8,87 g·100 gs.s.⁻¹) i doświadczalnym bez gliceryny (4,81 g·100 gs.s.⁻¹). W podłożach wzbogaconych 15 lub 20% obj. dodatkiem glicerolu największa objętościowa produktywność biosyntezy tłuszczu w komórkach stosowanego szczepu drożdży przekraczała 5 g·dm⁻³. Hodowla wgłębna drożdży Rhodotorula gracilis w podłożu stanowiącym odpadową wodę sokową ziemniaczaną wzbogaconą glicerolem w ilości 15–20% obj. prowadzi do biosyntezy tłuszczu wewnątrzkomórkowego.The biosynthesis of intracellular fat by oleaginous yeast strains based on alternative sources of carbon, nitrogen, phosphorus and mineral ingredients can provide the opportunity for the utilization of the industrial wastes. The culture media for SCO production can include glycerol from biodiesel production as a source of carbon as well as potato wastewater as a source of nitrogen. Potato wastewater is a waste of the production of protein feed obtained by proteins thermal-acid coagulation from potato juice. The aim of the study was to determine the ability of Rhodotorula gracilis yeast to the growth and intracellular biosynthesis of fat during 72-hour bath cultivation in experimental media containing potato wastewater enriched with glycerol. Experimental media contained potato wastewater and diverse addition of glycerol in quantities of 5, 10, 15 or 20% vol. Control medium was YPD. Potato wastewater originated from PEPEES SA Food Industry in Łomża (Central East Poland). The biomass yield, intracellular fat content as well as glycerol in cultivation media content were determined during yeast cultivation. Biomass yield was performed by gravimetric method, while glycerol content by the Milchert’s method. The intracellular fat content was determined after extraction according to the Soxhlet method with petroleum ether. The highest yield of the cell biomass (28.65 gs.s.·dm⁻³) was obtained in the experimental medium with wastewater and 5% of glycerol. Culturing of the yeast of Rhodotorula gracilis in medium containing potato wastewater media enriched with 15 or 20% glycerol leads to the biosynthesis of intracellular fat. The intracellular biosynthesis of fat in the experimental media glycerol occurred in the stationary growth phase. The highest intracellular fat (25.57 g·100 gs.s.⁻¹) was found in yeast biomass from the experimental media containing 20% glycerol. In comparison to the fat content in the biomass from YPD control medium (8.87 g·100 gs.s.⁻¹) and experimental without glycerol (4.81 g·100 gs.s.⁻¹) the value was about 3 and 5 times greater respectively. The volumetric productivity of fat in cells of the yeast strain tested exceeded 5 g·dm⁻³ in potato wastewater media enriched with 15 or 20% glycerol. Increasing the glycerol content in the experimental media (from 5 to 20% vol) led to a reduction in glycerol utilization by yeast (from 86 to 59%). The fact of incomplete utilization of glycerol in experimental media should result in an extension of the submerged culture over 72 hours

Emerging glyco-based strategies to steer immune responses

Glycan structures are common posttranslational modifications of proteins, which serve multiple important structural roles (for instance in protein folding), but also are crucial participants in cell–cell communications and in the regulation of immune responses. Through the interaction with glycan-binding receptors, glycans are able to affect the activation status of antigen-presenting cells, leading either to induction of pro-inflammatory responses or to suppression of immunity and instigation of immune tolerance. This unique feature of glycans has attracted the interest and spurred collaborations of glyco-chemists and glyco-immunologists to develop glycan-based tools as potential therapeutic approaches in the fight against diseases such as cancer and autoimmune conditions. In this review, we highlight emerging advances in this field, and in particular, we discuss on how glycan-modified conjugates or glycoengineered cells can be employed as targeting devices to direct tumor antigens to lectin receptors on antigen-presenting cells, like dendritic cells. In addition, we address how glycan-based nanoparticles can act as delivery platforms to enhance immune responses. Finally, we discuss some of the latest developments in glycan-based therapies, including chimeric antigen receptor (CAR)-T cells to achieve targeting of tumor-associated glycan-specific epitopes, as well as the use of glycan moieties to suppress ongoing immune responses, especially in the context of autoimmunity

Recent advances on smart glycoconjugate vaccines in infections and cancer

Vaccination is one of the greatest achievements in biomedical research preventing death and morbidity in many infectious diseases through the induction of pathogen-specific humoral and cellular immune responses. Currently, no effective vaccines are available for pathogens with a highly variable antigenic load, such as the human immunodeficiency virus or to induce cellular T-cell immunity in the fight against cancer. The recent SARS-CoV-2 outbreak has reinforced the relevance of designing smart therapeutic vaccine modalities to ensure public health. Indeed, academic and private companies have ongoing joint efforts to develop novel vaccine prototypes for this virus. Many pathogens are covered by a dense glycan-coat, which form an attractive target for vaccine development. Moreover, many tumor types are characterized by altered glycosylation profiles that are known as “tumor-associated carbohydrate antigens”. Unfortunately, glycans do not provoke a vigorous immune response and generally serve as T-cell-independent antigens, not eliciting protective immunoglobulin G responses nor inducing immunological memory. A close and continuous crosstalk between glycochemists and glycoimmunologists is essential for the successful development of efficient immune modulators. It is clear that this is a key point for the discovery of novel approaches, which could significantly improve our understanding of the immune system. In this review, we discuss the latest advancements in development of vaccines against glycan epitopes to gain selective immune responses and to provide an overview on the role of different immunogenic constructs in improving glycovaccine efficacy