Functional characterization of α-Gal producing lactic acid bacteria with potential probiotic properties

The dichotomy between probiotic lactic acid bacteria and Plasmodium: A promising therapeutic avenue

Our understanding of gut microbial populations and their immense influence on host immunity, health, and diseases has increased deeply in recent years. Numerous reports have identified the role of mosquito and mammalian gut microbiota in the modulation of host susceptibility to Plasmodium infection. Artemisinin resistance in malaria-endemic regions necessitates the development of new, safer, and more affordable treatments to supplement existing therapies. In this review, we compiled a colossal amount of data from numerous studies that have assessed the roles played by gut microbial communities in Plasmodium infection, progression, transmission, and severity. Most interestingly, our study points to the overwhelming evidence from experimental studies in mural malaria to human trials, suggesting that the presence of lactic acid bacteria in the gut microbiota of mammalian hosts provides a great degree of protection against malaria. Therefore, our study provides a compelling narrative for probiotic administration as an adjunct therapy for combatting malaria.

Tick bites, IgE to galactose-alpha-1,3-galactose and urticarial or anaphylactic reactions to mammalian meat: The alpha-gal syndrome

The recent recognition of a syndrome of tick-acquired mammalian meat allergy has transformed the previously held view that mammalian meat is an uncommon allergen. The syndrome, mediated by IgE antibodies against the oligosaccharide galactose-alpha-1,3-galactose (alpha-gal), can also involve reactions to visceral organs, dairy, gelatin and other products, including medications sourced from non-primate mammals. Thus, fittingly, this allergic disorder is now called the alpha-gal syndrome (AGS). The syndrome is strikingly regional, reflecting the important role of tick bites in sensitization, and is more common in demographic groups at risk of tick exposure. Reactions in AGS are delayed, often by 2-6 h after ingestion of mammalian meat. In addition to classic allergic symptomatology such as urticaria and anaphylaxis, AGS is increasingly recognized as a cause of isolated gastrointestinal morbidity and alpha-gal sensitization has also been linked with cardiovascular disease. The unusual link with tick bites may be explained by the fact that allergic cells and mediators are mobilized to the site of tick bites and play a role in resistance against ticks and tick-borne infections. IgE directed to alpha-gal is likely an incidental consequence of what is otherwise an adaptive immune strategy for host defense against endo- and ectoparasites, including ticks.

Weissella cibaria Relieves Gut Inflammation Caused by Escherichia coli through Inflammation Modulation and Gut Microbiota Regulation

The emergence of multi-drug-resistant (MDR) pathogens has considerably challenged the development of new drugs. Probiotics that inhibit MDR pathogens offer advantages over chemical antibiotics and drugs due to their increased safety and fewer side effects. This study reported that Weissella cibaria P-8 isolated from pickles showed excellent antibacterial activity against intestinal pathogens, particularly the antibacterial activity against MDR Escherichia coli B2 was the highest. This study showed that the survival rates of W. cibaria P-8 at pH 2.0 and 0.3% bile salt concentration were 72% and 71.56%, respectively, and it still had antibacterial activity under pepsin, trypsin, protease K, and catalase hydrolysis. Moreover, W. cibaria P-8 inhibits the expression of inflammatory factors interleukin-1β, tumor necrosis factor-α, and interleukin-6, upregulates the interleukin-10 level, and increases total antioxidant capacity and superoxide dismutase enzyme activity in serum. W. cibaria P-8 also efficiently repairs intestinal damage caused by E. coli infection. The gut microbiota analysis demonstrated that W. cibaria P-8 colonizes the intestine and increases the abundance of some beneficial intestinal microorganisms, particularly Prevotella. In conclusion, W. cibaria P-8 alleviated MDR E. coli-induced intestinal inflammation by regulating inflammatory cytokine and enzyme activity and rebalancing the gut microbiota, which could provide the foundation for subsequent clinical analyses and probiotic product development.

Gene-edited pigs: a translational model for human food allergy against alpha-Gal and anaphylaxis

The prevalence of food allergy is rising and is estimated to approach 10%. Red meat allergy is the first known food allergy elicited by immunoglobulin E (IgE) antibodies recognizing a carbohydrate. Due to the loss of function of the alpha-1,3-galactosyltransferase (GGTA1) gene in humans, the disaccharide galactose-α-1,3-galactose (α-Gal) cannot be synthesized and therefore became immunogenic. IgE sensitization is elicited through the skin by repetitive tick bites transmitting α-Gal. The underlying mechanisms regarding innate and adaptive immune cell activation, including the B-cell isotype switch to IgE, are poorly understood, requiring further research and physiologically relevant animal models. Here, we describe a new animal model of red meat allergy using percutaneous α-Gal sensitization of gene-edited GGTA1-deficient pigs. Total and α-Gal-specific IgG, IgG1, IgG2, IgG4, and IgE levels were tracked. Further key factors associated with allergic skin inflammation, type 2 immunity, and allergy development were measured in PBMCs and skin samples. Significant increases in α-Gal-specific IgG1 and IgE levels indicated successful sensitization to the allergen α-Gal. Intracutaneous sensitizations with α-Gal recruited lymphocytes to the skin, including elevated numbers of T helper 2 (Th2) cells. Finally, α-Gal-sensitized pigs not only recognized α-Gal as non-self-antigen following α-Gal exposure through the skin but also developed anaphylaxis upon antigen challenge. Based on the similarities between the porcine and human skin, this new large animal model for α-Gal allergy should help to unveil the consecutive steps of cutaneous sensitization and aid the development of prophylactic and treatment interventions.

An α-Gal antigenic surrogate as a biomarker of treatment evaluation in Trypanosoma cruzi-infected children. A retrospective cohort study

BACKGROUND

Proper evaluation of therapeutic responses in Chagas disease is hampered by the prolonged persistence of antibodies to Trypanosoma cruzi measured by conventional serological tests and by the lack of sensitivity of parasitological tests. Previous studies indicated that tGPI-mucins, an α-Gal (α-d-Galp(1→3)-β-d-Galp(1→4)-d-GlcNAc)-rich fraction obtained from T. cruzi trypomastigotes surface coat, elicit a strong and protective antibody response in infected individuals, which disappears soon after successful treatment. The cost and technical difficulties associated with tGPI-mucins preparation, however, preclude its routine implementation in clinical settings.

METHODS/PRINCIPLE FINDINGS

We herein developed a neoglycoprotein consisting of a BSA scaffold decorated with several units of a synthetic α-Gal antigenic surrogate (α-d-Galp(1→3)-β-d-Galp(1→4)-β-d-Glcp). Serological responses to this reagent, termed NGP-Tri, were monitored by means of an in-house enzyme-linked immunosorbent assay (α-Gal-ELISA) in a cohort of 82 T. cruzi-infected and Benznidazole- or Nifurtimox-treated children (3 days to 16 years-old). This cohort was split into 3 groups based on the age of patients at the time of treatment initiation: Group 1 comprised 24 babies (3 days to 5 months-old; median = 26 days-old), Group 2 comprised 31 children (7 months to 3 years-old; median = 1.0-year-old) and Group 3 comprised 26 patients (3 to 16 years-old; median = 8.4 years-old). A second, control cohort (Group 4) included 39 non-infected infants (3 days to 5 months-old; median = 31 days-old) born to T. cruzi-infected mothers. Despite its suboptimal seroprevalence (58.4%), α-Gal-ELISA yielded shorter median time values of negativization (23 months [IC 95% 7 to 36 months] vs 60 months [IC 95% 15 to 83 months]; p = 0.0016) and higher rate of patient negative seroconversion (89.2% vs 43.2%, p < 0.005) as compared to conventional serological methods. The same effect was verified for every Group, when analyzed separately. Most remarkably, 14 out of 24 (58.3%) patients from Group 3 achieved negative seroconversion for α-Gal-ELISA while none of them were able to negativize for conventional serology. Detailed analysis of patients showing unconventional serological responses suggested that, in addition to providing a novel tool to shorten follow-up periods after chemotherapy, the α-Gal-ELISA may assist in other diagnostic needs in pediatric Chagas disease.

CONCLUSIONS/SIGNIFICANCE

The tools evaluated here provide the cornerstone for the development of an efficacious, reliable, and straightforward post-therapeutic marker for pediatric Chagas disease.

Mechanistic insights into the interaction between the host gut microbiome and malaria

Malaria is a devastating infectious disease and significant global health burden caused by the bite of a Plasmodium-infected female Anopheles mosquito. Gut microbiota was recently discovered as a risk factor of severe malaria. This review entails the recent advances on the impact of gut microbiota composition on malaria severity and consequence of malaria infection on gut microbiota in mammalian hosts. Additionally, this review provides mechanistic insight into interactions that might occur between gut microbiota and host immunity which in turn can modulate malaria severity. Finally, approaches to modulate gut microbiota composition are discussed. We anticipate this review will facilitate novel hypotheses to move the malaria-gut microbiome field forward.

Glycan-related genes in human gut microbiota exhibit differential distribution and diversity in carbohydrate degradation and glycan synthesis

Interactions between humans and the gut microbiome occur by supplying nutrients to gut epithelial cells via short-chain fatty acids obtained from dietary carbohydrates or mucins and activating immunity via mucins' degradation. The degradation of carbohydrates derived from food is an important function for organisms to obtain energy. However, since humans possess only 17 genes encoding carbohydrate-degrading enzymes, the gut microbiome is responsible for degrading plant-derived polysaccharides. Using the method for extracting glycan-related genes from the metagenomes constructed thus far, we calculated the distribution and abundance of different glycan-related genes in the healthy human gut metagenome. Glycan-related genes showed an abundance of 0.64-11.00, indicating large individual differences. However, the distribution of the classes of glycan-related genes was similar between the samples. In addition, the function of carbohydrate degradation was divided into three clusters, showing high diversity; however, the synthesis function was not divided, indicating low diversity. The substrates of enzymes for carbohydrate degradation between clusters were either plant-derived polysaccharides or biased toward degrading polysaccharides derived from other sources. These functional biases differ depending on the type of microorganism used. Based on these findings, we predicted that 1) diversity will be constant because the influence on the host by the transferase of gut bacteria is a function derived from the genome, and 2) diversity will be high because the influence on the host by the hydrolase of gut bacteria is affected by incoming dietary carbohydrates.

Effect of different drying methods on the functional properties of probiotics encapsulated using prebiotic substances

Probiotics and prebiotics together work synergistically as synbiotics and confer various health benefits. Many studies on synbiotic foods only focus on the survival of probiotics but fail to evaluate their functional properties. The impact on functional properties should be explored to better understand its therapeutic efficacy. In this work, probiotics (Lactiplantibacillus plantarum NCIM 2083) were encapsulated with prebiotics (fructooligosaccharide + whey protein + maltodextrin) using spray-drying (SD), freeze-drying (FD), spray-freeze-drying (SFD), and refractance window-drying (RWD) techniques. Aggregation, intestinal adhesion, antagonistic activity, and bile salt hydrolase (BSH) activity of probiotics were studied before and after the encapsulation process. The SFD probiotics showed better aggregation ability (79% at 24-h incubation), on par with free cells (FC) (81% at 24-h incubation). The co-aggregation ability of encapsulated probiotics has drastic variations with each pathogenic strain. The adhesion ability of probiotics in chicken intestinal mucus was assessed by the crystal violet method, indicating no significant variations between FC and SFD probiotics. Also, encapsulated probiotics exhibit antagonistic activity (zone of inhibition in mm) against gut pathogens E. coli (11.33 to 17.34), S. faecalis (8.83 to 15.32), L. monocytogenes (13.67 to 18), S. boydii (12.17 to 15.5), and S. typhi (2.17 to 6.86). Overall, these studies confirm the significance and impact of various drying techniques on the functionality of encapsulated probiotics in synbiotic powders. KEY POINTS: • Understanding the relevance of processing effects on the functionality of probiotics. • Spray-freeze-dried probiotics showed superior functional properties. • The encapsulation process had no significant impact on bile salt hydrolase activity.