Peptide Immunization Research Articles

Effects of combined action of proline-rich peptides of human saliva with antimicrobial proteins

BACKGROUND: The substances that make up mixed saliva exhibit activity against bacteria, viruses and fungi. Among them are various cationic antimicrobial peptides: alpha- and beta-defensins, cathelicidins, histatins, but their concentration is relatively low. On the other hand, saliva widely contains a fraction of proline-rich proteins and products of their proteolysis — peptides, the functions of which currently remain poorly studied and unclear. The study of the antimicrobial activity of proline-rich proteins, in particular, when they act together with antimicrobial peptides, and the deciphering of the molecular and cellular basis for the implementation of the protective functions of proline-rich peptides is an urgent task in medicine and biology. The data obtained will help to understand the mechanisms of anti-infective protection of the oral cavity with the participation of the innate immune system, and in the future will allow the creation of drugs based on proline-rich proteins in humans and animals. AIM: Study of the individual antibacterial action of proline-rich salivary proteins, their combined action with the antimicrobial proteins lactoferrin and lysozyme, as well as with one of the most significant endogenous protective peptides — cathelicidin LL-37 on the formation of bacterial biofilms. MATERIALS AND METHODS: Human lactoferrin and egg lysozyme were used in the work. The minimum inhibitory concentrations of peptides against gram-negative and gram-positive bacteria were estimated using serial dilutions in a liquid nutrient medium. Using serial dilutions using the “chessboard” method, it was shown that proline-rich proteins can increase the antibacterial activity of innate immunity peptides present in the oral cavity. The ability of combinations of cationic proline-rich peptides with cathelicidin LL-37 to prevent the formation of bacterial biofilms was studied. RESULTS: In the presence of proline-rich peptides, the antimicrobial activity of some antimicrobial peptides and proteins present in saliva against planktonic bacteria increases. The combined action of proline-rich proteins with LL-37 increases the inhibition of bacterial biofilm formation. CONCLUSIONS: As a result of the study, it was shown that the analyzed cationic proline-rich peptides of human saliva exhibit anti-inflammatory effects, which suggests their significant role in the regulation of inflammatory processes in the oral cavity, as well as their participation in recovery processes.

Immunomodulatory peptides from sturgeon cartilage: Isolation, identification, molecular docking and effects on RAW264.7 cells

Sturgeons (Acipenseridae), ancient fish known for their caviar, produce underutilized by-products like protein-rich cartilage, which is a source of high-quality bioactive peptides. This study investigates immunomodulatory peptides from sturgeon cartilage hydrolysates mechanisms. The study found that sturgeon cartilage hydrolysate F2–7 and its key peptides(DHVPLPLP and HVPLPLP)significantly promoted RAW267.4 cell proliferation, NO release, and phagocytosis (P < 0.001).Additionally, western blotting confirmed that F2–7 enhances immune response by increasing the expression of P-IKKα/β, IΚΚ, p65, and P-p65 proteins in the NF-κB signalling pathway (P < 0.01). Molecular docking further demonstrated that DHVPLPLP and HVPLPLP bind to NF-κB pathway proteins via hydrogen bonding, with low estimated binding energies (−2.75 and −1.64; −6.04 and −4.75 kcal/mol), thus establishing their role as key immune peptides in F2–7. Therefore, DHVPLPLP and HVPLPLP have the potential to be developed as dietary supplements for immune enhancement. Their ability to enhance immune function provides a theoretical basis for novel immune supplements.

Antibacterial effects of human mesenchymal stem cells and their derivatives: a systematic review.

The growing problem of antimicrobial resistance (AMR) poses a significant challenge to public health; This is partly due to the lack of advancements in the development of novel antibiotics and the pressing need for alternative treatment options. Mesenchymal stem cells (MSC) possess secretory components that enhance the immune response and peptides that disrupt the bacteria constitution. The isolation of various human tissues has facilitated the investigation of the diverse potentials of MSC and their components. Further research is needed to fully understand the spectrum and efficacy of these elements and their differences. The primary aim of this study was to perform a thorough review of the current literature related to the antimicrobial properties of MSC and their associated components. The objective was to establish an insight into the results and effects of utilizing MSC in relation to bacterial colonization, and to present an overview of previously documented findings. This systematic literature review was conducted using the PubMed, Embase, and Web of Science databases. Data on the effect of MSC or their derivatives were measured by calculating the percentage of bacterial counts reduction after treatment with MSC in comparison to the control. A total of 3,911 articles were screened, and 31 eligible publications were selected for inclusion in the analysis. In the current systematic review, the majority of the experimental designs showed positive outcomes in terms of bacterial load reduction when MSC or their derivatives were used, with bone marrow being the most effective tissue. The rest of the findings exhibited heterogeneity in the spectrum of outcomes that could be attributed to the effects of using various tissues derived MSC in both in vivo and in vitro studies. The findings of our study indicate the potential antibacterial characteristics of MSC. The direct antimicrobial activity of these cells was demonstrated by our results, which quantitatively showed a decrease in bacterial growth after treatment with MSC. However, additional research is required to clarify the factors that determine the efficacy of their antimicrobial activity and their various components.

Testing AI predictions that hyperglycemia-induced non-enzymatic glycation of immune system proteins impairs diabetic immunity

People with type 1, type 2 and gestational diabetes, and newborns of diabetic mothers, have increased risks of contracting microbial infections such as SARS-CoV-2, amplifying comorbidity and mortality risks. Hyperglycemia and its associated hyperinflammation mediate these risks but by unknown mechanisms. We hypothesize that hyperglycemia results in glycation (non-enzymatic addition of sugars to free amino groups such as lysines) of antimicrobial and anti-inflammatory proteins and peptides that mediate innate and adaptive immunity. While glycation of hemoglobin A1c is used as a benchmark for glycemic control, studies of the effects of the glycation of immune system molecules are almost non-existent. Three AI protein-glycation prediction models demonstrate that immune system proteins and peptides such as serotransferrin, lactotransferrin, lysozyme, complement proteins, immunoglobulins, Toll-like receptors, etc., probably glycate at multiple sites affecting function. However, the AI-predicted glycation sites differed significantly among the three models employed. Therefore, three tests of these predictions were carried out. Predicted glycation sites were first evaluated in terms of clinically or experimentally identified glycation sites of homologous proteins and known effects of lysine substitutions at predicted glycation sites. Second, mass spectrometry was used to identify glycation sites on lactoferrin and human lysozyme. Third, the effects on the antimicrobial activity of lactotransferrin and lysozyme glycation were tested using a Candida albicans assay. Results of tests demonstrate that protein glycation occurs and interferes with immune function but that AI glycation prediction models are very inaccurate. Suggestions for improving AI accuracy are provided.

The SCOOP-MIK2 immune pathway modulates Arabidopsis root growth and development by regulating PIN-FORMED abundance and auxin transport.

Plants synthesize hundreds of small secretory peptides, which are perceived by the receptor-like kinase (RLK) family at the cell surface. Various signaling peptide-RLK pairs ensure plant adaptation to distinct environmental conditions. Here, we report that SERINE RICH ENDOGENOUS PEPTIDE (SCOOP) immune peptides modulate root growth and development by regulating PIN-FORMED (PIN)-regulated polar auxin transport in Arabidopsis. The SCOOP4 and SCOOP12 treatments impaired root gravitropic growth, auxin redistribution in response to gravistimulation, and PIN abundance in the PM. Furthermore, genetic and cell biological analyses revealed that these physiological and cellular effects of SCOOP4 and SCOOP12 peptides are mediated by the receptor MALE DISCOVERER1-INTERACTING RECEPTOR LIKE KINASE2 (MIK2) and the downstream mitogen-activated kinase MPK6. Biochemical evidence indicates that MPK6 directly phosphorylates the cytosolic loop of PIN proteins. Our work established a link between the immune signaling peptide SCOOPs and root growth pathways, providing insights into the molecular mechanisms underlying plant root adaptive growth in the defense response.

Stability of oil-in-water emulsion and immunomodulating activity in S180 tumor-bearing mice.

The stability and nutritional integrity of emulsions are susceptible to various factors including thermal treatment, solid-liquid ratio, and sterilization. In this study, the physicochemical stability and immunomodulatory activities of an oil-in-water emulsion containing immune peptides (TUFSE) were assessed through particle size, zeta potential, related cytokines, and so on. When the temperature was 70°C and a solid-liquid ratio of 1:4, the emulsion revealed stability at high-pressure homogenization, with the small particle size. The loss rates of vitamins were 8.57%-62.26% in 6 months at 25°C. After treatment with cyclophosphamide (CTX), lymphocyte proliferation activity in TUFSE-H group increased (p<0.05), and immune globulin levels were notably elevated (p<0.05) in TUFSE groups compared to model group. It confirms the parameters of the emulsion, suggesting its ability to be prepared with minimal vitamin loss while simultaneously improving the disease status in CTX-treated tumor-bearing mice. It shows potential as an immune-enhancing supplement with significant potential value. PRACTICAL APPLICATION: This study validated the parameters of the oil-in-water emulsion and showed that it can be stably prepared with minor vitamin loss while simultaneously improving the disease status in CTX-treated tumor-bearing mice. TUFSE-H group exhibited a notable increase in lymphocytes proliferation activity, whereas serum cytokines and immune globulin levels were elevated compared to MC group, indicating its potential as an immune-enhancing supplement with substantial value.

Development of Sensitive Anti-Mouse CCR5 Monoclonal Antibodies Using the N-Terminal Peptide Immunization.

One of the G protein-coupled receptors, C-C chemokine receptor 5 (CCR5), is an important regulator for the activation of T and B lymphocytes, dendritic cells, natural killer cells, and macrophages. Upon binding to its ligands, CCR5 activates downstream signaling, which is an important regulator in the innate and adaptive immune response through the promotion of lymphocyte migration and the secretion of proinflammatory cytokines. Anti-CCR5 monoclonal antibodies (mAbs) have been developed and evaluated in clinical trials for tumors and inflammatory diseases. In this study, we developed novel mAbs for mouse CCR5 (mCCR5) using the N-terminal peptide immunization. Among the established anti-mCCR5 mAbs, C5Mab-4 (rat IgG2a, kappa) and C5Mab-8 (rat IgG1, kappa), recognized mCCR5-overexpressing Chinese hamster ovary-K1 (CHO/mCCR5) and an endogenously mCCR5-expressing cell line (L1210) by flow cytometry. The dissociation constant (KD) values of C5Mab-4 and C5Mab-8 for CHO/mCCR5 were determined as 3.5 × 10-8 M and 7.3 × 10-9 M, respectively. Furthermore, both C5Mab-4 and C5Mab-8 could detect mCCR5 by western blotting. These results indicated that C5Mab-4 and C5Mab-8 are useful for detecting mCCR5 by flow cytometry and western blotting and provide a possibility to obtain the proof of concept in preclinical studies.

A suite of selective pressures supports the maintenance of alleles of a Drosophila immune peptide.

The innate immune system provides hosts with a crucial first line of defense against pathogens. While immune genes are often among the fastest evolving genes in the genome, in Drosophila , antimicrobial peptides (AMPs) are notable exceptions. Instead, AMPs may be under balancing selection, such that over evolutionary timescales multiple alleles are maintained in populations. In this study, we focus on the Drosophila antimicrobial peptide Diptericin A, which has a segregating amino acid polymorphism associated with differential survival after infection with the Gram-negative bacteria Providencia rettgeri . Diptericin A also helps control opportunistic gut infections by common Drosophila gut microbes, especially those of Lactobacillus plantarum . In addition to genotypic effects on gut immunity, we also see strong sex-specific effects that are most prominent in flies without functional diptericin A . To further characterize differences in microbiomes between different diptericin genotypes, we used 16S metagenomics to look at the microbiome composition. We used both lab reared and wild caught flies for our sequencing and looked at overall composition as well as the differential abundance of individual bacterial families. Overall, we find flies that are homozygous for one allele of diptericin A are better equipped to survive a systemic infection from P. rettgeri , but in general have a shorter lifespans after being fed common gut commensals. Our results suggest a possible mechanism for the maintenance of genetic variation of diptericin A through the complex interactions of sex, systemic immunity, and the maintenance of the gut microbiome.

Immunopeptides: immunomodulatory strategies and prospects for ocular immunity applications.

Immunopeptides have low toxicity, low immunogenicity and targeting, and broad application prospects in drug delivery and assembly, which are diverse in application strategies and drug combinations. Immunopeptides are particularly important for regulating ocular immune homeostasis, as the eye is an immune-privileged organ. Immunopeptides have advantages in adaptive immunity and innate immunity, treating eye immune-related diseases by regulating T cells, B cells, immune checkpoints, and cytokines. This article summarizes the application strategies of immunopeptides in innate immunity and adaptive immunity, including autoimmunity, infection, vaccine strategies, and tumors. Furthermore, it focuses on the mechanisms of immunopeptides in mediating ocular immunity (autoimmune diseases, inflammatory storms, and tumors). Moreover, it reviews immunopeptides' application strategies and the therapeutic potential of immunopeptides in the eye. We expect the immune peptide to get attention in treating eye diseases and to provide a direction for eye disease immune peptide research.

Bixafen, Prothioconazole, and Trifloxystrobin Alone or in Combination Have a Greater Effect on Health Related Gene Expression in Honey Bees from Nutritionally Deprived than from Protein Supplemented Colonies.

The aim of this study was to evaluate whether alterations in food availability compromise the metabolic homeostasis of honey bees exposed to three fungicides alone or together. Ten honey bee colonies were used, with half receiving carbohydrate-protein supplementation for 15 weeks while another five colonies had their protein supply reduced with pollen traps. Subsequently, forager bees were collected and exposed by contact to 1 or 7 µg of bixafen, prothioconazole, or trifloxystrobin, either individually or in combination. After 48 h, bee abdomens without the intestine were used for the analysis of expression of antioxidant genes (SOD-1, CAT, and GPX-1), detoxification genes (GST-1 and CYP306A1), the storage protein gene vitellogenin, and immune system antimicrobial peptide genes (defensin-1, abaecin, hymenoptaecin, and apidaecin), through real-time PCR. All fungicide treatments induced changes in gene expression, with bixafen showing the most prominent upregulation. Exposure to 1 µg of each of the three pesticides resulted in upregulation of genes associated with detoxification and nutrition processes, and downregulation of immune system genes. When the three pesticides were combined at a dose of 7 µg each, there was a pronounced downregulation of all genes. Food availability in the colonies affected the impact of fungicides on the expression of the studied genes in forager bees.

Nasal cathelicidin is expressed in early life and is increased during mild, but not severe respiratory syncytial virus infection

Respiratory syncytial virus is the major cause of acute lower respiratory tract infections in young children, causing extensive mortality and morbidity globally, with limited therapeutic or preventative options. Cathelicidins are innate immune antimicrobial host defence peptides and have antiviral activity against RSV. However, upper respiratory tract cathelicidin expression and the relationship with host and environment factors in early life, are unknown. Infant cohorts were analysed to characterise early life nasal cathelicidin levels, revealing low expression levels in the first week of life, with increased levels at 9 months which are comparable to 2-year-olds and healthy adults. No impact of prematurity on nasal cathelicidin expression was observed, nor were there effects of sex or birth mode, however, nasal cathelicidin expression was lower in the first week-of-life in winter births. Nasal cathelicidin levels were positively associated with specific inflammatory markers and demonstrated to be associated with microbial community composition. Importantly, levels of nasal cathelicidin expression were elevated in infants with mild RSV infection, but, in contrast, were not upregulated in infants hospitalised with severe RSV infection. These data suggest important relationships between nasal cathelicidin, upper airway microbiota, inflammation, and immunity against RSV infection, with interventional potential.

Individualized neoantigen peptide immunization of a metastatic pancreatic cancer patient: a case report of combined tumor and liquid biopsy

Individualized neoantigen peptide immunization of a metastatic pancreatic cancer patient: a case report of combined tumor and liquid biopsy

ANTICANCER IMMUNOGENIC POTENTIAL OF ONCOLYTIC PEPTIDES: RECENT ADVANCES AND NEW PROSPECTS

Oncolytic peptides are derived from natural host defense peptides/antimicrobial peptides produced in a wide variety of life forms. Over the past two decades, they have attracted much attention in both basic research and clinical applications. Oncolytic peptides were expected to act primarily on tumor cells and also trigger the immunogenic cell death. Their ability in the tumor microenvironment remodeling and potentiating the anticancer immunity has long been ignored. Despite the promising results, clinical application of oncolytic peptides is still hindered by their unsatisfactory bioactivity and toxicity to normal cells. To ensure safer therapy, various approaches are being developed. The idea of the Ukrainian research group was to equip peptide molecules with a "molecular photoswitch" — a diarylethene fragment capable of photoisomerization, allowing for the localized photoactivation of peptides within tumors reducing side effects. Such oncolytic peptides that may induce the membrane lysis-mediated cancer cell death and subsequent anticancer immune responses in combination with the low toxicity to normal cells have provided a new paradigm for cancer therapy. This review gives an overview of the broad effects and perspectives of oncolytic peptides in anticancer immunity highlighting the potential issues related to the use of oncolytic peptides in cancer immunotherapy. We summarize the current status of research on peptide-based tumor immunotherapy in combination with other therapies including immune checkpoint inhibitors, chemotherapy, and targeted therapy.

Abstract 4111: Multi-peptide cancer vaccines targeting KRAS induce significant anti-tumor efficacy

Abstract Background and objective: Kirsten rat sarcoma viral oncogene homologue (KRAS) is frequently mutated in human cancers. KRAS mutants offer the potential for the development of cancer-specific immunotherapy, as epitopes harbouring mutations are strong neoantigens to which the immune system generates cancer-specific anti-tumor effects. However, previous clinical trials of KRAS-targeted vaccines failed to generate satisfactory anti-cancer efficacy. Evidence suggested that CD4 T cell activity plays a critical role in augmenting the cytotoxic effect of CD8 T cells. Here, we design long peptides based on the MHC II hotspots on the entire KRAS protein that activate both CD4 and CD8 T cells to kill KRAS-driven cancer cells. Long peptides also cover a wider range of HLA alleles to increase their utility in a broader spectrum of patients. Our objective is to create a multi-peptide vaccine simultaneously targeting the mutant and wild-type (WT) regions of human KRAS protein. Methods: By selecting MHC II hotspots via multiple epitope prediction algorithms, we designed and synthesized 8 long peptides with lengths between 25 to 30mers. One of them harboured a G12D mutation, while the others covered the WT regions of KRAS. In addition, the corresponding keyhole limpet hemocyanin (KLH) conjugated peptides were also generated. We first demonstrated their immunogenicity in mouse in vivo models. Different combinations of peptides adjuvanted with either CpG oligodeoxynucleotide + aluminum (CpG+alum) or complete/incomplete Freud’s adjuvant (CFA/IFA) were immunized into Balb/c mice before determining the immune response by mouse interferon γ (mIFNγ) ELISPOT assay. Subsequently, an in vivo prophylactic anti-tumor study was conducted by immunizing this multi-peptide vaccine in Balb/c mice and observing the growth inhibition of the CT26-derived tumors. Results: T cell responses were observed in two peptide mixes with or without G12D mutation, suggesting that both mutant-harbouring peptide and WT peptides were immunogenic. We showed that KLH-conjugated peptides and CpG+alum elicited stronger immune responses than the naked peptides and CFA/IFA respectively. Furthermore, peptide mapping showed that the G12D mutant-harbouring peptide and two other WT peptides may contribute to the overall T cell response in the Balb/c mouse. In the prophylactic anti-tumor study (n = 10), immunization of KRAS naked peptide and KLH-conjugated peptide vaccines significantly inhibited tumor growth by 51.2% (****p &amp;lt; 0.0001) and 44.7% (***p &amp;lt; 0.001) respectively, compared to control. Subsequent mIFNγ ELISPOT assay showed that the tumor inhibitory effect was attributed to the activation of antigen-specific T cell response of the vaccines. Conclusion: Our multi-peptide vaccines targeting both the mutant and WT regions of KRAS could generate KRAS-specific T cell responses and elicit significant anti-tumor effect in mouse models. Citation Format: Chi Han Samson Li, Melvin Toh. Multi-peptide cancer vaccines targeting KRAS induce significant anti-tumor efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4111.

Abstract 4105: Immune-modulating vaccines targeting CD73

Abstract Background: To realize the generalizable regulation of the tumor microenvironment (TME), immune-modulating vaccines are developed to target shared antigens expressed by immunosuppressive cells and cancer cells. CD73, also known as ecto-5'-nucleotidase, is a pivotal enzyme in the adenosine metabolic pathway and is expressed on the surface of multiple cancer cells and immunosuppressive cells in the TME. In this study, we aim to develop a CD73-targeting immune modulatory peptide vaccine by predicting antigen sequences, screening immunogenic antigen peptides, and assessing their anti-tumor efficacy and capacity to improve the TME. Methods: The expression level of CD73 on various cancer cell lines were evaluated by flow cytometry. Several online software were used to predict CD73-derived peptides that bind to the mouse MHC-I (major histocompatibility complex class I) molecules. Cells from the draining lymph nodes of healthy mice and peptide-immunized mice were harvested and stimulated by the synthetic peptides in vitro. T cell activation level, IFN-γrelease degree and their cytolytic capability towards cancer cells was measured. CD73-derived peptides were mixed with CpG to treat 4T1 tumor-bearing mice and the changes in the TME were investigated by flow cytometry. The online website (www.camoip.net) was used to analyze the correlation between CD73 expression and patient survival in the TCGA Breast invasive carcinoma (BRCA) cohort.Results: 4T1 exhibited a strikingly elevated surface expression of CD73 compared to other mouse cancer cell lines. Three CD73-derived peptides (EP1, EP2, EP3) consisting of 8-10 amino acids were synthesized. In vitro stimulation experiments indicated that EP1 and EP3 significantly elicited T-cell responses in draining lymph nodes. After stimulation, the proportions of CD25+, CD69+, CD107a+, and CD137+ cells markedly increased in CD8+ T cell populations. These cells also displayed enhanced cytotoxicity against 4T1 tumor cells. In vivo experiments demonstrated that EP3 induced a pronounced anti-tumor response in an established 4T1 tumor model without evident toxicity. Moreover, subcutaneous injection of EP3 improves the TME by promoting antigen-specific CD8+ T-cell responses, reducing M2 macrophages, and inducing neutrophil maturation. High tumor CD73 expression was also found to be associated with poor outcomes among BRCA patients, which further indicated clinical relevance. Conclusions: In this study, we successfully identified an immunogenic vaccine targeting CD73. It expressed dual functionality by effectively triggering cytotoxic T-cell responses that directly killing CD73-highexpressing tumor cells and regulating the tumor microenvironment through eliminating immunosuppressive cells with elevated CD73 expression. These findings hold promise for a novel immune-modulating vaccine and suggest a potential therapeutic avenue for the treatment of breast cancer and other types of cancer. Citation Format: Yuting Luo, Tao Shi, Hanbing Wang, Baorui Liu, Jia Wei. Immune-modulating vaccines targeting CD73 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4105.

Epitope Mapping of an Anti-CD44v4 Monoclonal Antibody (C44Mab-108) Using Enzyme-Linked Immunosorbent Assay.

CD44 is a type I transmembrane glycoprotein and possesses various isoforms which are largely classified into CD44 standard (CD44s) and CD44 variant (CD44v) isoforms. Some variant-encoded regions play critical roles in tumor progression. However, the function of CD44 variant 4 (CD44v4)-encoded region has not been fully understood. Using peptide immunization, we developed an anti-CD44v4 monoclonal antibody, C44Mab-108, which is useful for flow cytometry, western blotting, and immunohistochemistry. In this study, we determined the critical epitope of C44Mab-108 by enzyme-linked immunosorbent assay (ELISA). We used the alanine (or glycine)-substituted peptides of the CD44v4-encoded region (amino acids 271-290 of human CD44v3-10) and found that C44Mab-108 did not recognize the alanine-substituted peptides of D280A and W281A. Furthermore, these peptides could not inhibit the recognition of C44Mab-108 in flow cytometry and immunohistochemistry. The results indicate that the critical binding epitope of C44Mab-108 includes Asp280 and Trp281 of CD44v3-10.

The aged microenvironment impairs BCL6 and CD40L induction in CD4+ T follicular helper cell differentiation.

Weakened germinal center responses by the aged immune system result in diminished immunity against pathogens and reduced efficacy of vaccines. Prolonged contacts between activated B cells and CD4+ T cells are crucial to germinal center formation and T follicular helper cell (Tfh) differentiation, but it is unclear how aging impacts the quality of this interaction. Peptide immunization confirmed that aged mice have decreased expansion of antigen-specific germinal center B cells and reduced antibody titers. Furthermore, aging was associated with accumulated Tfh cells, even in naïve mice. Despite increased numbers, aged Tfh had reduced expression of master transcription factor BCL6 and increased expression of the ectonucleotidase CD39. Invitro activation revealed that proliferative capacity was maintained in aged CD4+ T cells, but not the costimulatory molecule CD40L. When activated invitro by aged antigen-presenting cells, young CD4+ naïve T cells generated reduced numbers of activated cells with upregulated CD40L. To determine the contribution of cell-extrinsic influences on antigen-specific Tfh induction, young, antigen-specific B and CD4+ T cells were adoptively transferred into aged hosts prior to peptide immunization. Transferred cells had reduced expansion and differentiation into germinal center B cell and Tfh and reduced antigen-specific antibody titers when compared to young hosts. Young CD4+ T cells transferred aged hosts differentiated into Tfh cells with reduced PD-1 and BCL6 expression, and increased CD39 expression, though they maintained their mitochondrial capacity. These results highlight the role of the lymphoid microenvironment in modulating CD4+ T cell differentiation, which contributes to impaired establishment and maintenance of germinal centers.

Exploration of hypoglycemic peptides from porcine collagen based on network pharmacology and molecular docking.

In recent years, the extraction of hypoglycemic peptides from food proteins has gained increasing attention. Neuropeptides, hormone peptides, antimicrobial peptides, immune peptides, antioxidant peptides, hypoglycemic peptides and antihypertensive peptides have become research hotspots. In this study, bioinformatic methods were used to screen and predict the properties of pig collagen-derived hypoglycemic peptides, and their inhibitory effects on α-glucosidase were determined in vitro. Two peptides (RL and NWYR) were found to exhibit good water solubility, adequate ADMET (absorption, distribution, metabolism, elimination, and toxicity) properties, potentially high biological activity, and non-toxic. After synthesizing these peptides, NWYR showed the best inhibitory effect on α-glucosidase with IC50 = 0.200±0.040 mg/mL, and it can regulate a variety of biological processes, play a variety of molecular functions in different cellular components, and play a hypoglycemic role by participating in diabetic cardiomyopathy and IL-17 signaling pathway. Molecular docking results showed that NWYR had the best binding effect with the core target DPP4 (4n8d), with binding energy of -8.8 kcal/mol. NWYR mainly bonded with the target protein through hydrogen bonding, and bound with various amino acid residues such as Asp-729, Gln-731, Leu-765, etc., thus affecting the role of the target in each pathway. It is the best core target for adjuvant treatment of T2DM. In short, NWYR has the potential to reduce type 2 diabetes, providing a basis for further research or food applications as well as improved utilization of pig by-products. However, in subsequent studies, it is necessary to further verify the hypoglycemic ability of porcine collagen active peptide (NWYR), and explore the hypoglycemic mechanism of NWYR from multiple perspectives such as key target genes, protein expression levels and differences in metabolites in animal models of hyperglycemia, which will provide further theoretical support for its improvement in the treatment of T2DM.

An update on the taxonomy and functional properties of the probiotic Enterococcus faecium SF68.

Enterococcus faecium SF68 (SF68) is a well-known probiotic with a long history of safe use. Recent changes in the taxonomy of enterococci have shown that a novel species, Enterococcus lactis, is closely related with E. faecium and occurs together with other enterococci in a phylogenetically well-defined E. faecium species group. The close phylogenetic relationship between the species E. faecium and E. lactis prompted a closer investigation into the taxonomic status of E. faecium SF68. Using phylogenomics and ANI, the taxonomic analysis in this study showed that probiotic E. faecium SF68, when compared to other E. faecium and E. lactis type and reference strains, could be re-classified as belonging to the species E. lactis. Further investigations into the functional properties of SF68 showed that it is potentially capable of bacteriocin production, as a bacteriocin gene cluster encoding the leaderless bacteriocin EntK1 together with putative Lactococcus lactis bacteriocins LsbA, and LsbB-like putative immunity peptide (LmrB) were found located in an operon on plasmid pF9. However, bacteriocin expression was not studied. Competitive exclusion experiments in co-culture over 7 days at 37°C showed that the probiotic SF68 could inhibit the growth of specific E. faecium and Listeria monocytogenes strains, while showing little or no inhibitory activity towards an entero-invasive Escherichia coli and a Salmonella Typhimurium strain, respectively. In cell culture experiments with colon carcinoma HT29 cells, the probiotic SF68 was also able to strain-specifically inhibit adhesion and/or invasion of enterococcal and L. monocytogenes strains, while such adhesion and invasion inhibition effects were less pronounced for E. coli and Salmonella strains. This study therefore provides novel data on the taxonomy and functional properties of SF68, which can be reclassified as Enterococcus lactis SF68, thereby enhancing the understanding of its probiotic nature.

Differential expression of antimicrobial peptide encoding genes of honey bee (Apis mellifera) after Varroa mite (Varroa destructor) infestation

Varroa destructor mite is a serious threat to the world apiculture industry, and severely hampered beekeeping practices. Innate immune systems are key defenses of animals and are particularly important in species that lack the sophisticated adaptive immune systems found in vertebrates. In honey bees, antimicrobial immune peptide genes play a significant immune response against pathogens. The present study analyzed the detrimental effects of Varroa infestation on Apis mellifera at all developmental stages in both Varroa challenged and controlled hives. Physical attributes were observed in Varroa hives at different time intervals (0, 30, and 45 days respectively). After 45 days of Varroa exposure, the samples were taken, and the AMPs immune response of bees parasitized by Varroa was detected by studying the expression levels of antibacterial peptides (defensin, apidaecin, abaecin, and hymenoptaecin). Significant alterations in the physical parameters viz. body length, body weight, wing shape, and mean numbers of brood cells were observed compared to the control. Colony density was also decreased with marked negative behavioural changes. Ct values of Real-Time PCR results showed that AMP-specific immune gene transcription level in Varroa-challenged bees was downregulated, except for abaecin and defensin (adult stage). There was a significant (p < 0.05) increase in abaecin gene transcription folds i.e., 1.064 larvae, 1.732 pupae, and 1.264 adults bees. As a whole, all these findings can be taken as critical biomarkers in the advancement of control techniques against Varroa and other pathogen infections as a part of wide-ranging programs of honey bee health and Varroa control.