Annexin A5 binds to lipopolysaccharide and reduces its endotoxin activity

Predictive biomarkers for latent Mycobacterium tuberculosis infection

Tuberculosis is a leading cause of infectious death worldwide, with almost a fourth of the world's population latently infected with its causative agent, Mycobacterium tuberculosis. Current diagnostic methods are insufficient to differentiate between healthy and latently infected populations. Here, we used a machine learning approach to analyze publicly available proteomic data from saliva and serum in Ethiopia's healthy, latent TB (LTBI) and active TB (ATBI) people. Our analysis discovered a profile of six proteins, Mast Cell Expressed Membrane Protein-1, Hemopexin, Lamin A/C, Small Proline Rich Protein 2F, Immunoglobulin Kappa Variable 4-1, and Voltage Dependent Anion Channel 2 that can precisely differentiate between the healthy and latently infected populations. This data suggests that a combination of six host proteins can serve as accurate biomarkers to diagnose latent infection. This is important for populations living in high-risk areas as it may help in the surveillance and prevention of severe disease.

Postbiotic-based recombinant receptor activator of NF-κB ligand enhanced oral vaccine efficiency in chicken

Functional M cells are differentiated by receptor activator of NF-κB ligand (RANKL) and capture of luminal antigens to initiate immune responses. We aimed to use postbiotic-based recombinant chicken RANKL (cRANKL) to promote M cell differentiation and test the efficacy of oral vaccines. Chicks were divided into three groups that were administered phosphate-buffered saline (PBS), cell extracts of wild-type Lactococcus lactis subsp. lactis IL1403 (WT_CE), or cell extracts of recombinant L. lactis expressing cRANKL (cRANKL_CE). The expression of the M cell marker was measured, and the gut microbiome was profiled. The efficiency of the infectious bursal disease (IBD) vaccine was tested after 12 consecutive days of administering cRANKL_CE. The chickens that were administered cRANKL_CE (p = 0.038) had significantly higher Annexin A5 (ANXA5) mRNA expression levels than those in the PBS group (PBS vs. WT_CE, p = 0.657). In the gut microbiome analysis, no significant changes were observed. However, the relative abundance of Escherichia-Shigella was negatively correlated (r =  - 0.43, p = 0.019) with ANXA5 mRNA expression in Peyer's patches. cRANKL_CE/IBD (p = 0.018) had significantly higher IBD-specific faecal IgA levels than PBS/IBD (PBS/IBD vs. WT_CE/IBD, p = 0.217). Postbiotic-based recombinant cRANKL effectively improved the expression of M cell markers and the efficiency of oral vaccines. No significant changes were observed in the gut microbiome after administration of postbiotic-based recombinant cRANKL. This strategy can be used for the development of feed additives and adjuvants. KEY POINTS: • Postbiotic-based recombinant cRANKL enhanced the expression of ANXA5 in chicken. • The relative abundance of Escherichia-Shigella was negatively correlated with ANXA5 expression. • Postbiotic-based recombinant cRANKL effectively improved the efficiency of oral vaccine.

Insights into membrane interactions and their therapeutic potential

Recent research into membrane interactions has uncovered a diverse range of therapeutic opportunities through the bioengineering of human and non-human macromolecules. Although the majority of this research is focussed on fundamental developments, emerging studies are showcasing promising new technologies to combat conditions such as cancer, Alzheimer's and inflammatory and immune-based disease, utilising the alteration of bacteriophage, adenovirus, bacterial toxins, type 6 secretion systems, annexins, mitochondrial antiviral signalling proteins and bacterial nano-syringes. To advance the field further, each of these opportunities need to be better understood, and the therapeutic models need to be further optimised. Here, we summarise the knowledge and insights into several membrane interactions and detail their current and potential uses therapeutically.

Pharmacokinetics of recombinant human annexin A5 (SY-005) in patients with severe COVID-19

Objective: Annexin A5 is a phosphatidylserine binding protein with anti-inflammatory, anticoagulant and anti-apoptotic properties. Preclinical studies have shown that annexin A5 inhibits pro-inflammatory responses and improves organ function and survival in rodent models of sepsis. This clinical trial aimed to evaluate the pharmacokinetic (PK) properties of the recombinant human annexin A5 (SY-005) in severe COVID-19. Methods: This was a pilot randomized, double-blind, placebo-controlled trial. Severe COVID-19 patients were randomly assigned to receive intravenous 50 μg/kg (low dose, n = 3), 100 μg/kg (high dose, n = 5) of SY-005 or placebo (n = 5) every 12 h for 7 days. Plasma SY-005 levels were assessed using enzyme-linked immunosorbent assay (ELISA) and the PK parameters were determined using non-compartmental analysis. Results: All patients treated with SY-005 had a normal baseline estimated glomerular filtration rate (eGFR, 104-125 mL/min/1.73 m2). Both low and high doses of SY-005 were cleared within 6 h after intravenous administration. Plasma maximum concentrations (Cmax), half-life, clearance and volume distribution of low and high doses of SY-005 were 402.4 and 848.9 ng/mL, 0.92 and 0.96 h, 7.52 and 15.19 L/h, and 9.98 and 20.79 L, respectively. Daily pre-dose circulating annexin A5 levels were not significantly different when SY-005 was administered at the low or the high dose 12-h intervals. There was no significant effect on activated partial thromboplastin time (aPTT) or INR (international normalized ratio of prothrombin time) during 7 days of SY-005 treatment. Conclusion: SY-005 doses of 50 and 100 μg/kg were detectable and subsequently cleared from the plasma in severe COVID-19 patients with normal baseline renal function. There was no significant plasma SY-005 accumulation 6 h after drug administration and coagulation was not altered during 7 days of treatment. Clinical trials Registration: This study was registered with ClinicalTrials.gov (NCT04748757, first posted on 10 February 2021).

Selective protein aggregation confines and inhibits endotoxins in wounds: Linking host defense to amyloid formation

Bacterial lipopolysaccharide (LPS) induces rapid protein aggregation in human wound fluid. We aimed to characterize these LPS-induced aggregates and their functional implications using a combination of mass spectrometry analyses, biochemical assays, biological imaging, cell experiments, and animal models. The wound-fluid aggregates encompass diverse protein classes, including sequences from coagulation factors, annexins, histones, antimicrobial proteins/peptides, and apolipoproteins. We identified proteins and peptides with a high aggregation propensity and verified selected components through Western blot analysis. Thioflavin T and Amytracker staining revealed amyloid-like aggregates formed after exposure to LPS in vitro in human wound fluid and in vivo in porcine wound models. Using NF-κB-reporter mice and IVIS bioimaging, we demonstrate that such wound-fluid LPS aggregates induce a significant reduction in local inflammation compared with LPS in plasma. The results show that protein/peptide aggregation is a mechanism for confining LPS and reducing inflammation, further emphasizing the connection between host defense and amyloidogenesis.

The most prominent modulated annexins during parasitic infections

Annexins (ANXs) exert different functions in cell biological and pathological processes and are thus known as double or multi-faceted proteins. These sophisticated proteins might express on both parasite structure and secretion and in parasite-infected host cells. In addition to the characterization of these pivotal proteins, describing their mechanism of action can be also fruitful in recognizing their roles in the pathogenesis of parasitic infections. Accordingly, this study presents the most prominent ANXs thus far identified and their relevant functions in parasites and infected host cells during pathogenesis, especially in the most important intracellular protozoan parasitic infections including leishmaniasis, toxoplasmosis, malaria and trypanosomiasis. The data provided in this study demonstrate that the helminth parasites most probably express and secret ANXs to develop pathogenesis while the modulation of the host-ANXs could be employed as a crucial strategy by intracellular protozoan parasites. Moreover, such data highlight that the use of analogs of both parasite and host ANX peptides (which mimic or regulate ANXs physiological functions through various strategies) might suggest novel therapeutic insights into the treatment of parasitic infections. Furthermore, due to the prominent immunoregulatory activities of ANXs during most parasitic infections and the expression levels of these proteins in some parasitic infected tissues, such multifunctional proteins might be also potentially relevant as vaccine and diagnostic biomarkers. We also suggest some prospects and insights that could be useful and applicable to form the basis of future experimental studies.

Maternal prenatal immunity, neonatal trained immunity, and early airway microbiota shape childhood asthma development

BACKGROUND

The path to childhood asthma is thought to initiate in utero and be further promoted by postnatal exposures. However, the underlying mechanisms remain underexplored. We hypothesized that prenatal maternal immune dysfunction associated with increased childhood asthma risk (revealed by low IFN-γ:IL-13 secretion during the third trimester of pregnancy) alters neonatal immune training through epigenetic mechanisms and promotes early-life airway colonization by asthmagenic microbiota.

METHODS

We examined epigenetic, immunologic, and microbial features potentially related to maternal prenatal immunity (IFN-γ:IL-13 ratio) and childhood asthma in a birth cohort of mother-child dyads sampled pre-, peri-, and postnatally (N = 155). Epigenome-wide DNA methylation and cytokine production were assessed in cord blood mononuclear cells (CBMC) by array profiling and ELISA, respectively. Nasopharyngeal microbiome composition was characterized at age 2-36 months by 16S rRNA sequencing.

RESULTS

Maternal prenatal immune status related to methylome profiles in neonates born to non-asthmatic mothers. A module of differentially methylated CpG sites enriched for microbe-responsive elements was associated with childhood asthma. In vitro responsiveness to microbial products was impaired in CBMCs from neonates born to mothers with the lowest IFN-γ:IL-13 ratio, suggesting defective neonatal innate immunity in those who developed asthma during childhood. These infants exhibited a distinct pattern of upper airway microbiota development characterized by early-life colonization by Haemophilus that transitioned to a Moraxella-dominated microbiota by age 36 months.

CONCLUSIONS

Maternal prenatal immune status shapes asthma development in her child by altering the epigenome and trained innate immunity at birth, and is associated with pathologic upper airway microbial colonization in early life.

Mucosal delivery of nanovaccine strategy against COVID-19 and its variants

Despite the global administration of approved COVID-19 vaccines (e.g., ChAdOx1 nCoV-19®, mRNA-1273®, BNT162b2®), the number of infections and fatalities continue to rise at an alarming rate because of the new variants such as Omicron and its subvariants. Including COVID-19 vaccines that are licensed for human use, most of the vaccines that are currently in clinical trials are administered via parenteral route. However, it has been proven that the parenteral vaccines do not induce localized immunity in the upper respiratory mucosal surface, and administration of the currently approved vaccines does not necessarily lead to sterilizing immunity. This further supports the necessity of a mucosal vaccine that blocks the main entrance route of COVID-19: nasal and oral mucosal surfaces. Understanding the mechanism of immune regulation of M cells and dendritic cells and targeting them can be another promising approach for the successful stimulation of the mucosal immune system. This paper reviews the basic mechanisms of the mucosal immunity elicited by mucosal vaccines and summarizes the practical aspects and challenges of nanotechnology-based vaccine platform development, as well as ligand hybrid nanoparticles as potentially effective target delivery agents for mucosal vaccines.

Shiga Toxin-Producing Escherichia coli and Milk Fat Globules

Shiga toxin-producing Escherichia coli (STEC) are zoonotic Gram-negative bacteria. While raw milk cheese consumption is healthful, contamination with pathogens such as STEC can occur due to poor hygiene practices at the farm level. STEC infections cause mild to serious symptoms in humans. The raw milk cheese-making process concentrates certain milk macromolecules such as proteins and milk fat globules (MFGs), allowing the intrinsic beneficial and pathogenic microflora to continue to thrive. MFGs are surrounded by a biological membrane, the milk fat globule membrane (MFGM), which has a globally positive health effect, including inhibition of pathogen adhesion. In this review, we provide an update on the adhesion between STEC and raw MFGs and highlight the consequences of this interaction in terms of food safety, pathogen detection, and therapeutic development.

Buccal and Sublingual Vaccines: A Review on Oral Mucosal Immunization and Delivery Systems

Currently, most vaccines available on the market are for parental use; however, this may not be the best option on several occasions. Mucosal routes of administration such as intranasal, sublingual, and buccal generate great interest due to the benefits they offer. These range from increasing patient compliance to inducing a more effective immune response than that achieved through conventional routes. Due to the activation of the common mucosal immune system, it is possible to generate an effective systemic and local immune response, which is not achieved through parenteral administration. Protection against pathogens that use mucosal entry routes is provided by an effective induction of mucosal immunity. Mucosal delivery systems are being developed, such as films and microneedles, which have proven to be effective, safe, and easy to administer. These systems have multiple advantages over commonly used injections, which are simple to manufacture, stable at room temperature, painless for the patient since they do not require puncture. Therefore, these delivery systems do not require to be administered by medical personnel; in fact, they could be self-administered.

Advancedoral vaccine delivery strategies for improving the immunity

Infectious diseases continue to inflict a high global disease burden. The consensus is that vaccination is the most effective option against infectious diseases. Oral vaccines have unique advantages in the prevention of global pandemics due to their ease of use, high compliance, low cost, and the ability to induce both systemic and mucosal immune responses. However, challenges of adapting vaccines for oral administration remain significant. Foremost among these are enzymatic and pH-dependent degradation of antigens in the stomach and intestines, the low permeability of mucus barrier, the nonspecific uptake of antigens at the intestinal mucosal site, and the immune suppression result from the elusive immune tolerance mechanisms. Innovative delivery techniques promise great potential for improving the flexibility and efficiency of oral vaccines. A better understanding of the delivery approaches and the immunological mechanisms of oral vaccine delivery systems may provide new scientific insight and tools for developing the next-generation oral vaccine. Here, an overview of the advanced technologies in the field of oral vaccination is proposed, including mucus-penetrating nanoparticle (NP), mucoadhesive delivery vehicles, targeting antigen-presenting cell (APC) nanocarriers and enhanced paracellular delivery strategies and so on. Meanwhile, the mechanisms of delivery vectors interact with mucosal barriers are discussed.

Therapeutic Potential of Annexins in Sepsis and COVID-19

Sepsis is a continuing problem in modern healthcare, with a relatively high prevalence, and a significant mortality rate worldwide. Currently, no specific anti-sepsis treatment exists despite decades of research on developing potential therapies. Annexins are molecules that show efficacy in preclinical models of sepsis but have not been investigated as a potential therapy in patients with sepsis. Human annexins play important roles in cell membrane dynamics, as well as mediation of systemic effects. Most notably, annexins are highly involved in anti-inflammatory processes, adaptive immunity, modulation of coagulation and fibrinolysis, as well as protective shielding of cells from phagocytosis. These discoveries led to the development of analogous peptides which mimic their physiological function, and investigation into the potential of using the annexins and their analogous peptides as therapeutic agents in conditions where inflammation and coagulation play a large role in the pathophysiology. In numerous studies, treatment with recombinant human annexins and annexin analogue peptides have consistently found positive outcomes in animal models of sepsis, myocardial infarction, and ischemia reperfusion injury. Annexins A1 and A5 improve organ function and reduce mortality in animal sepsis models, inhibit inflammatory processes, reduce inflammatory mediator release, and protect against ischemic injury. The mechanisms of action and demonstrated efficacy of annexins in animal models support development of annexins and their analogues for the treatment of sepsis. The effects of annexin A5 on inflammation and platelet activation may be particularly beneficial in disease caused by SARS-CoV-2 infection. Safety and efficacy of recombinant human annexin A5 are currently being studied in clinical trials in sepsis and severe COVID-19 patients.

Emerging Phage Resistance in Pseudomonas aeruginosa PAO1 Is Accompanied by an Enhanced Heterogeneity and Reduced Virulence

Bacterial surface structures of a proteinic nature and glycoconjugates contribute to biofilm formation and provide shields to host defense mechanisms (e.g., the complement system and phagocytosis). A loss or alteration of these molecules, leading to phage resistance, could result in fewer virulent bacteria. In this study, we evaluate the biology and phenotype changes in Pseudomonas aeruginosa PAO1 phage-resistant clones, which emerge in phage-treated biofilms. We characterize these clones for phage-typing patterns, antibiotic resistance, biofilm formation, pathogenicity, and interactions with the innate immune system. Another important question that we address is whether phage-resistant mutants are also generated incidentally, despite the phage treatment-selective pressure, as the natural adaptation of the living biofilm population. It is found that the application of different phages targeting a particular receptor selects similar phage resistance patterns. Nevertheless, this results in a dramatic increase in the population heterogeneity, giving over a dozen phage-typing patterns, compared to one of the untreated PAO1 sessile forms. We also confirm the hypothesis that "phage-resistant bacteria are more susceptible to antibiotics and host-clearance mechanisms by the immune system". These findings support phage application in therapy, although the overall statement that phage treatment selects the less virulent bacterial population should be further verified using a bigger collection of clinical strains.

Diannexin Can Ameliorate Acute Respiratory Distress Syndrome in Rats by Promoting Heme Oxygenase-1 Expression

Background

The recombinant protein diannexin can inhibit platelet-mediated events, which contribute to acute respiratory distress syndrome (ARDS). Here, we investigated the effect of diannexin and its effect on heme oxygenase-1 (HO-1) in ARDS.

Methods

A total of 32 rats were randomized into sham, ARDS, diannexin (D), and diannexin+HO-1 inhibitor (DH) groups. Alveolar-capillary permeability was evaluated by testing the partial pressure of oxygen to fraction of inspired oxygen (PaO₂/FiO₂) ratio, lung wet/dry weight ratio, and protein levels in the lung. Inflammation was assessed by measuring cytokine levels in the bronchial alveolar lavage fluid (BALF) and serum and nuclear factor-κB (NF-κB) in the lung tissue. Inducible nitric oxide synthase (iNOS), malondialdehyde (MDA), and myeloperoxidase (MPO) were measured to evaluate the oxidative stress response. Lung tissue pathology and apoptosis were also evaluated. We measured HO-1 expression in the lung tissue to investigate the effect of diannexin on HO-1 in ARDS.

Results

Compared with the ARDS group, diannexin improved PaO₂/FiO₂, lung wet/dry weight ratio, and protein levels in the BALF and decreased levels of cytokines and NF-κB in the lung and serum. Diannexin inhibited the oxidative stress response and significantly ameliorated pathological lung injury and apoptosis. The partial reversal of diannexin effects by a HO-1 inhibitor suggests that diannexin may promote HO-1 expression to ameliorate ARDS.

Conclusions

We showed that diannexin can improve alveolar-capillary permeability, inhibit the oxidative stress response and inflammation, and protect against ARDS-induced lung injury and apoptosis.

Understanding the mechanism of action of peptide (p-BthTX-I)2 derived from C-terminal region of phospholipase A2 (PLA2)-like bothropstoxin-I on Gram-positive and Gram-negative bacteria

Based on the antimicrobial activity of bothropstoxin-I (BthTX-I) and on the premise that a C-terminal peptide of Lys49 myotoxin can reproduce the antimicrobial activity of the parent protein, we aimed to study the mechanism of action of a peptide derived from the C-terminal region of the myotoxin BthTX-I [(p-BthTX-I)₂, sequence: KKYRYHLKPFCKK, disulfide-linked dimer] against Gram-positive and Gram-negative bacteria. Fluorescence quenching technique showed that the carboxyfluorescein labeled-peptide [CF-(p-BthTX-I)₂] when incubated with E. coli displayed a superior penetration activity than when incubated with S. aureus. Cell death induced by the peptide (p-BthTX-I)₂ showed a loss of membrane integrity in E. coli and S. aureus; however, the mechanisms of cell death were different, characterized by the presence of necrosis-like and apoptosis-like deaths, respectively. Scanning electron microscopy studies in E. coli and S. aureus showed morphological changes in the cells, with superficial deformities, appearance of wrinkles and bubbles, and formation of vesicles. Our results demonstrate that the mechanism of action of the peptide (p-BthTX-I)₂ is different in Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria. Knowledge of the mechanism of action of these peptides is important, since they are promising prototypes for new antimicrobial drugs.

Secretion of Recombinant Human Annexin V in Fusion with the Super Folder GFP for Labelling Phosphatidylserine-Exposing Membranes

Annexin V (ANXV), mostly characterized by its ability to interact with biological membranes in a calcium-dependent manner. ANXV interacts mainly with phosphatidylserine (PS), for that fluorescent ANXV widely produced and used as a sensitive and specific probe to mark apoptotic cells or any PS-containing bilayers membranes. Many reports described the prokaryotic expression of recombinant human ANXV. To overcome some of E. coli expression limitations, we aimed in this work to investigate unconventional alternative expression system in mammalian cells for producing secreted human ANXV in fusion with the super folder green fluorescent protein (sfGFP). HEK239T cells were transfected using polyethylenimine (PEI) and pcDNA-sfGFP-ANXV plasmid. Forty-eight hours post transfection, direct fluorescence measurement, immunoblotting and ELISA confirmed the presence of secreted sfGFP-ANXV in cells supernatant. The yield of secreted 6 × His-tagged sfGFP-ANXV after affinity purification was estimated to be around 2 µg per 1 ml of cells supernatant. The secretion system was proper to produce a fully functional sfGFP-ANXV fusion protein in quantities enough to recognize and bind PS-containing surfaces or liposomes. Besides, biological assays such as flow cytometry and fluorescent microscopy confirmed the capacity of the secreted sfGFP-ANXV to detect PS exposure on apoptotic cells. Taken together, we present mammalian expression as a quick, affordable and endotoxin-free system to produce sfGFP-ANXV fusion protein. The secreted sfGFP-ANXV in eukaryotic system is a promising biotechnological tool, it opens up new horizons for additional applications in the detection of PS bearing surfaces and apoptosis in vitro and in vivo assays.

Overexpression of annexin A5 might guide the gemtuzumab ozogamicin treatment choice in patients with pediatric acute myeloid leukemia

Background:

Acute myeloid leukemia (AML) is a common hematological malignancy. Gemtuzumab ozogamicin (GO), a humanized anti-CD33 antibody conjugated with the potent anti-tumor antibiotic calicheamicin, represents a promising targeted therapy for AML. Annexin A5 (ANXA5) is a proposed marker for the clinical prognosis of AML to guide treatment choice.

Methods:

In total, 253 patients with pediatric AML were enrolled and divided into two treatment groups: conventional chemotherapy alone and conventional chemotherapy in combination with GO. Univariate, multivariate, and Kaplan–Meier survival analyses were conducted to assess risk factors and clinical outcomes, and to estimate hazard ratios (HRs) and their 95% confidence interval. The level of statistical significance was set at p < 0.05.

Results:

In the GO treatment group, high ANXA5 expression was considered a favorable prognostic factor for overall survival (OS) and event-free survival (EFS). Multivariate analysis showed that high ANXA5 expression was an independent favorable factor for OS (HR = 0.629, p = 0.084) and EFS (HR = 0.544, p = 0.024) distinct from the curative effect of GO treatment. When all patients were again divided into two groups, this time based on the median expression of ANXA5, patients undergoing chemotherapy combined with GO had significantly better OS (p = 0.0012) and EFS (p = 0.0003) in the ANXA5 high-expression group. Gene set enrichment analysis identified a relevant series of pathways associated with glutathione metabolism, leukocyte transendothelial migration, and hematopoietic cell lineage.

Conclusion:

The expression level of ANXA5 can help optimize the treatment regimen for individual patients, and patients with overexpression of ANXA5 may circumvent poor outcomes from chemotherapy combined with GO.

Chemical Proteomic Profiling of Lysophosphatidic Acid-Binding Proteins

Lysophosphatidic acid (LPA) is an endogenous cell signaling molecule, and dysregulation of LPA signaling pathways is accompanied by several types of cancer. Herein, we developed a chemical proteomic method for the proteome-wide identification of LPA-binding proteins. The method involves the synthesis of a desthiobiotin-conjugated LPA acyl phosphate probe for the covalent labeling, enrichment, and subsequent LC-MS/MS identification of LPA-binding proteins at the proteome-wide level. By conducting labeling reactions at two different probe concentrations (10 and 100 μM) in conjunction with an SILAC (stable isotope labeling by amino acids in cell culture)-based workflow, we characterized the LPA-binding capabilities of these proteins at the entire proteome scale, which led to the identification of 86 candidate LPA-binding proteins in HEK293T cells. Moreover, we validated that two of these proteins, annexin A5 and phosphoglycerate kinase 1, can bind directly with LPA. Together, we developed a novel LPA probe for the identification and characterizations of LPA-binding proteins from the entire human proteome. The method should be adaptable for the identification of other lipid-binding proteins.

Formulation technologies for oral vaccines

Many options now exist for constructing oral vaccines which, in experimental systems, have shown themselves to be able to generate highly effective immunity against infectious diseases. Their suitability for implementation in clinical practice, however, for prevention of outbreaks, particularly in low- and middle-income countries (LMIC), is not always guaranteed, because of factors such as cost, logistics and cultural and environmental conditions. This brief overview provides a summary of the various approaches which can be adopted, and evaluates them from a pharmaceutical point, taking into account potential regulatory issues, expense, manufacturing complexity, etc., all of which can determine whether a vaccine approach will be successful in the late stages of development. Attention is also drawn to problems arising from inadequate diet, which impacts upon success in stimulating effective immunity, and identifies the use of lipid-based carriers as a way to counteract the problem of nutritional deficiencies in vaccination campaigns.

Differential Expression of Inflammation-Related Genes in Down Syndrome Patients with or without Periodontal Disease

Aim

Aware that Down Syndrome patients present among their clinical characteristics impaired immunity, the aim of this study is to identify the statistically significant differences in inflammation-related gene expression by comparing Down Syndrome patients with Periodontal Disease (DS+PD+) with Down Syndrome patients without Periodontal Disease (DS+PD-), and their relationship with periodontitis as a chronic oral inflammatory clinical feature.

Materials and Methods

Case study and controls on eleven Down Syndrome patients (DS+PD+ vs. DS+PD-). RNA was extracted from peripheral blood using a Qiagen PAXgene Blood miRNA Kit when performing an oral examination. A search for candidate genes (92 selected) was undertaken on the total genes obtained using a Scientific GeneChip® Scanner 3000 (Thermo Fisher Scientific) and Clariom S solutions for human, mouse, and rat chips, with more than 20,000 genes annotated for measuring expression levels.

Results

Of the 92 inflammation-related genes taken initially, four genes showed a differential expression across both groups with a p value of <0.05 from the data obtained using RNA processing of the patient sample. Said genes were TNFSF13B (p = 0.0448), ITGB2 (p = 0.0033), ANXA3 (p = 0.0479), and ANXA5 (p = 0.016).

Conclusions

There are differences in inflammation-related gene expression in Down Syndrome patients when comparing patients who present a state of chronic oral inflammation with patients with negative rates of periodontal disease.

Calcium Regulates the Nuclear Localization of Protein Arginine Deiminase 2

Protein arginine deiminases (PADs) are calcium-dependent enzymes that mediate the post-translational conversion of arginine into citrulline. Dysregulated PAD activity is associated with numerous autoimmune disorders and cancers. In breast cancer, PAD2 citrullinates histone H3R26 and activates the transcription of estrogen receptor target genes. However, PAD2 lacks a canonical nuclear localization sequence, and it is unclear how this enzyme is transported into the nucleus. Here, we show for the first time that PAD2 translocates into the nucleus in response to calcium signaling. Using BioID2, a proximity-dependent biotinylation method for identifying interacting proteins, we found that PAD2 preferentially associates with ANXA5 in the cytoplasm. Binding of calcium to PAD2 weakens this cytoplasmic interaction, which generates a pool of calcium-bound PAD2 that can interact with Ran. We hypothesize that this latter interaction promotes the translocation of PAD2 into the nucleus. These findings highlight a critical role for ANXA5 in regulating PAD2 and identify an unusual mechanism whereby proteins translocate between the cytosol and nucleus.

M cell targeting engineered biomaterials for effective vaccination

Vaccines are one of the greatest medical interventions of all time and have been successful in controlling and eliminating a myriad of diseases over the past two centuries. Among several vaccination strategies, mucosal vaccines have wide clinical applications and attract considerable interest in research, showing potential as innovative and novel therapeutics. In mucosal vaccination, targeting (microfold) M cells is a frontline prerequisite for inducing effective antigen-specific immunostimulatory effects. In this review, we primarily focus on materials engineered for use as vaccine delivery platforms to target M cells. We also describe potential M cell targeting areas, methods to overcome current challenges and limitations of the field. Furthermore, we present the potential of biomaterials engineering as well as various natural and synthetic delivery technologies to overcome the challenges of M cell targeting, all of which are absent in current literature. Finally, we briefly discuss manufacturing and regulatory processes to bring a robust perspective on the feasibility and potential of this next-generation vaccine technology.

M CELLS ARE THE IMPORTANT POST IN THE INITIATION OF IMMUNE RESPONSE IN INTESTINE

Microfold cells (M cells) are specialized intestinal epithelial cells that initiate mucosal immune responses. These unique phagocytic epithelial cells are specialized for the transfer of a broad range of particulate antigens and microorganisms across the follicle-associated epithelium (FAE) into the gut-associated lymphoid tissue (GALT) by a process termed transcytosis. The molecular basis of antigen uptake by M cells has been gradually identified in the last decade. Active sampling of intestinal antigen initiates regulated immune responses that ensure intestinal homeostasis. The delivery of luminal substances across the intestinal epithelium to the immune system is a critical event in immune surveillance resulting in tolerance to dietary antigens and immunity to pathogens (e.g., bacteria, viruses, and parasites) and their toxins. Several specialized mechanisms transport luminal antigen across the gut epithelium. Discovery of M cell-specific receptors are of great interest, which could act as molecular tags for targeted delivery oral vaccine to M cells. Recent studies demonstrated that M cells utilize several receptors to recognize and transport specific luminal antigens. Vaccination through the mucosal immune system can induce effective systemic immune responses simultaneously with mucosal immunity. How this process is regulated is largely unknown. This review aims to show a new understanding of the factors that influence the development and function of M cells; to show the molecules expressed on M cells which appear to be used as immunosurveillance receptors to sample pathogenic microorganisms in the gut; to note how certain pathogens appear to exploit M cells to inject the host; and, finally, how this knowledge is used to specifically "target" antigens to M cells to attempt to improve the efficacy of mucosal vaccines. Recently, substantial progress has been made in our understanding of the factors that influence the development and function of M cells.

Annexin A5 Protein as a Potential Biomarker for the Diagnosis of Asthma

PURPOSE

Annexin A5 (ANXA5) has a potential role in cellular signal transduction, inflammation, and fibrosis. However, the exact role of ANXA5 in asthma remains to be clarified. The aims of the present study were to investigate ANXA5 protein expression in a mouse model of asthma and pollutant exposure and to elucidate the relationships between clinical variables and plasma ANXA5 levels in patients with asthma.

METHODS

A murine model of asthma induced by ovalbumin (OVA) and titanium dioxide (TiO₂) nanoparticles has been established using BALB/c mice, and we examined ANXA5 expression and lung fibrosis using this model. Moreover, we also compared ANXA5 plasma levels in patients with controlled vs. exacerbated asthma.

RESULTS

ANXA5 protein levels were lower in lung tissue from OVA + OVA mice than in control mice. Lung ANXA5, connective tissue growth factor (CTGF), and transforming growth factor β1 (TGF-β1) protein levels were higher in OVA + TiO₂-exposed mice than in control or OVA + OVA mice. Although Dermatophagoides pteronyssinus (Derp1) treatment increased lung ANXA5 protein levels in MRC-5 cells and A549 epithelial cells, it decreased lung ANXA5 levels in NHBE cells. Treatment with TiO₂ nanoparticles increased lung ANXA5, CTGF, and TGF-β1 protein levels in MRC-5 cells, A549 epithelial cells, and NHBE cells. Plasma ANXA5 levels were lower in asthmatic patients than in healthy controls, and they were significantly enriched in patients with exacerbated asthma compared with those with controlled asthma (P < 0.05). ANXA5 levels were correlated with pulmonary function as assessed by spirometry.

CONCLUSION

Our results imply that ANXA5 plays a potential role in asthma pathogenesis and may be a promising marker for exacerbated bronchial asthma and exposure to air pollutants.

Annexin A5 regulates hepatocarcinoma malignancy via CRKI/II-DOCK180-RAC1 integrin and MEK-ERK pathways

As a calcium-dependent phospholipid binding annexin protein, annexin A5 (Anxa5) links to the progression, metastasis, survival, and prognosis of a variety of cancers. Current work showed ANXA5 overexpression was positively correlated with the upregulations of CRKI/II and RAC1 in hepatocarcinoma (HCC) patients’ tissues, which potentially enhanced the clinical progression and lymphatic metastasis of HCC. The role and action mechanism of ANXA5 in hepatocarcinoma was then investigated using a hepatocarcinoma Hca-P cell line, an ideal and well-established murine cell model with 100% inducible tumorigenicity of implanted mice with low (~25%) lymph node metastatic (LNM) rate. In vitro evidences indicated ANXA5 stable knockdown resulted in decreased proliferation, migration, invasion and adhesion to lymph node (LN), and increased intercellular cohesion behaviors of hepatocarcinoma Hca-P cells. Consistently, stable ANXA5 knockdown led to reduced in vivo tumorigenicity and malignancy, LNM rate and level potentials of Hca-P- transplanted mice via inhibiting CD34 and VEGF3. The levels of CRKI/II and RAC1 were reduced in tumor tissues from mice transplanted with Hca-P cells with stable ANXA5 knockdown. Molecular action investigation further showed ANXA5 downregulation apparently suppressed the expressions of molecules CRKI/II, DOCK180, RAC1 in integrin pathway, p-MEK, p-ERK, c-Myc, and MMP-9 in MEK- ERK pathway together with VIMINTIN in Hca-P cells in appropriate to knockdown extent. Collectively, Anxa5 was able to mediate HCC carcinogenesis via integrin and MEK-ERK pathways. It is of potential use in the research and treatment of HCC.

Cell-Derived Nanoparticles are Endogenous Modulators of Sepsis With Therapeutic Potential

Cell-derived nanoparticles (CDNPs) containing cytosolic proteins and RNAs/DNAs can be isolated from stressed eukaryotic cells. Previously, CDNPs isolated from cultured cells exerted immunomodulatory activities in different infections. Here, we sought to elucidate the role of CDNPs using a murine model of cecal ligation and puncture (CLP). We hypothesized that CDNPs influence the immune response at the site of infection, where severe cellular stress occurs. We observed early CDNP accumulation in the peritoneum after 4 h and continued CDNP presence 24 h after CLP. To determine whether CDNPs influence the host response to sepsis, we isolated CDNPs from a murine fibroblast cell line stressed by nutrient-deprivation, and injected them into septic mice. CDNP-treated mice demonstrated decreased peritoneal interleukin 6 levels and an approximately 2-log lower bacterial load compared with control mice 24 h after CLP. Additionally, a 20% CFU reduction was observed when incubating CDNPs with Pseudomona aeroginosa, indicating that CDNPs are bactericidal. To identify CDNP-responsive cells, CFSE-labeled CDNPs were injected into mice at the time of CLP. We observed that CDNPs were preferentially ingested by F4/80 macrophages, and to a lesser degree, associated with inflammatory monocytes and neutrophils. Strikingly, CDNP-ingesting cells demonstrated elevated CD11b and MHCII expression compared with control cells. Altogether, our data indicate that CDNPs enhance the immune response at the site of infection and promote bacterial clearance, by direct bacterial killing and increasing phagocyte activation. Thus, CDNPs represent a novel, unexplored endogenous sepsis modulator with therapeutic potential.

Vaccination against Salmonella Infection: the Mucosal Way

Salmonella enterica subspecies enterica includes several serovars infecting both humans and other animals and leading to typhoid fever or gastroenteritis. The high prevalence of associated morbidity and mortality, together with an increased emergence of multidrug-resistant strains, is a current global health issue that has prompted the development of vaccination strategies that confer protection against most serovars. Currently available systemic vaccine approaches have major limitations, including a reduced effectiveness in young children and a lack of cross-protection among different strains. Having studied host-pathogen interactions, microbiologists and immunologists argue in favor of topical gastrointestinal administration for improvement in vaccine efficacy. Here, recent advances in this field are summarized, including mechanisms of bacterial uptake at the intestinal epithelium, the assessment of protective host immunity, and improved animal models that closely mimic infection in humans. The pros and cons of existing vaccines are presented, along with recent progress made with novel formulations. Finally, new candidate antigens and their relevance in the refined design of anti-Salmonella vaccines are discussed, along with antigen vectorization strategies such as nanoparticles or secretory immunoglobulins, with a focus on potentiating mucosal vaccine efficacy.

The gastrointestinal tract: properties and role in allogeneic hematopoietic stem cell transplantation

INTRODUCTION

The GI-tract is a major target for both the intensive chemo and/or radiotherapy conditioning as well as for GVHD and therefore is closely associated with transplant outcome. Apart from being a target, the GI-tract is also a mediator and therefore is also a key player of the pathogenetic process following allogeneic transplantation. Areas covered: The intestinal homeostasis is regulated through complicated interactions between the key players of this process which are the intestinal epithelium, the intestinal immune system, and the intestinal microbiota. A brief description of these elements, based on published english-language articles in PubMed, as well as their role during the process of allo-HSCT is discussed in this review. Expert commentary: Data on GI-tract properties suggest a central role for the intestine in regulation of immunity, both in healthy - steady state conditions and in pathological states such as during allo-HSCT. Given the fact that in the allogeneic transplant setting severe complications such as infections and GVHD are limiting this treatment modality, understanding the mechanisms that mediate intestinal homeostasis could lead to new preventive methods and improved outcomes.

The development of mucosal vaccines for both mucosal and systemic immune induction and the roles played by adjuvants

Vaccination is the most successful immunological practice that improves the quality of human life and health. Vaccine materials include antigens of pathogens and adjuvants potentiating the effectiveness of vaccination. Vaccines are categorized using various criteria, including the vaccination material used and the method of administration. Traditionally, vaccines have been injected via needles. However, given that most pathogens first infect mucosal surfaces, there is increasing interest in the establishment of protective mucosal immunity, achieved by vaccination via mucosal routes. This review summarizes recent developments in mucosal vaccines and their associated adjuvants.

Annexin A5 increases survival in murine sepsis model by inhibiting HMGB1-mediated pro-inflammation and coagulation

The identification of HMGB1 as a late-mediator in sepsis has highlighted HMGB1 as a promising therapeutic target for sepsis treatment. Recent studies have revealed that annexin A5, a 35 kDa Ca²⁺-dependent phospholipid binding protein, exerts anti-inflammatory effect by inhibiting LPS binding to TLR4/MD2 complex. Annexin A5 administration has been shown to protect against endotoxin lethality even when the treatment was given after the early cytokine response, which prompted our group to suspect that annexin A5 may inhibit the binding of HMGB1, as well as endotoxin to TLR4. Here we suggest annexin A5 as a new inhibitor of HMGB1-mediated pro-inflammatory cytokine production and coagulation in sepsis. We first confirmed the inhibitory role of annexin A5 in LPS-induced production of pro-inflammatory cytokines both in vitro and in vivo. We observed that annexin A5 protects against tissue damage and organ dysfunction during endotoxemia in vivo. We then assessed the inhibiting role of annexin A5 in HMGB1/TLR4 interaction, and showed that annexin A5 treatment reduces HMGB1-mediated cytokines IL6 and TNFα both in vitro and in vivo. Finally, we confirmed that anticoagulant property of annexin A5 persists in various septic conditions including elevated HMGB1. Overall, we suggest annexin A5 as an alternative therapeutic approach for controlling HMGB1-mediated pro-inflammation and coagulation in patients with sepsis.

Roles of M cells in infection and mucosal vaccines

The mucosal immune system plays a crucial part in the control of infection. Exposure of humans and animals to potential pathogens generally occurs through mucosal surfaces, thus, strategies that target the mucosa seem rational and efficient vaccination measures. Vaccination through the mucosal immune system can induce effective systemic immune responses simultaneously with mucosal immunity compared with parenteral vaccination. M cells are capable of transporting luminal antigens to the underlying lymphoid tissues and can be exploited by pathogens as an entry portal to invade the host. Therefore, targeting M-cell-specific molecules might enhance antigen entry, initiate the immune response, and induce protection against mucosal pathogens. Here, we outline our understanding of the distribution and function of M cells, and summarize the advances in mucosal vaccine strategies that target M cells.

Delivery strategies to enhance oral vaccination against enteric infections

While the majority of human pathogens infect the body through mucosal sites, most licensed vaccines are injectable. In fact the only mucosal vaccine that has been widely used globally for infant and childhood vaccination programs is the oral polio vaccine (OPV) developed by Albert Sabin in the 1950s. While oral vaccines against Cholera, rotavirus and Salmonella typhi have also been licensed, the development of additional non-living oral vaccines against these and other enteric pathogens has been slow and challenging. Mucosal vaccines can elicit protective immunity at the gut mucosa, in part via antigen-specific secretory immunoglobulin A (SIgA). However, despite their advantages over the injectable route, oral vaccines face many hurdles. A key challenge lies in design of delivery strategies that can protect antigens from degradation in the stomach and intestine, incorporate appropriate immune-stimulatory adjuvants and control release at the appropriate gastrointestinal site. A number of systems including micro and nanoparticles, lipid-based strategies and enteric capsules have significant potential either alone or in advanced combined formulations to enhance intestinal immune responses. In this review we will outline the opportunities, challenges and potential delivery solutions to facilitate the development of improved oral vaccines for infectious enteric diseases.

M cell-derived vesicles suggest a unique pathway for trans-epithelial antigen delivery

M cells are a subset of mucosal epithelial cells with specialized capability to transport antigens across the mucosal barrier, but there is limited information on antigen transfer in the subepithelial zone due to the challenges in tracking microparticles and antigens that are transcytosed by this unique cell. Using transgenic reporter mice expressing dsRed in the cytoplasm of M cells and EGFP in myeloid cells, we observed that the M cell basolateral pocket hosts a close interaction between B lymphocytes and dendritic cells. Interestingly, we identified a population of previously undescribed M cell-derived vesicles (MCM) that are constitutively shed into the subepithelial space and readily taken up by CX3CR1(+)CD11b(+) CD11c(+) dendritic cells. These MCM are characterized by their cytoplasmic dsRed confirming their origin from the M cell cytoplasm. MCM showed preferential colocalization in dendritic cells with transcytosed bacteria but not transcytosed polystyrene beads, indicating a selective sorting of cargo fate in the subepithelial zone. The size and number of MCM were found to be upregulated by bacterial transcytosis and soluble toll-like receptor 2 (TLR2) agonist, further pointing to dynamic regulation of this mechanism. These results suggest that MCM provide a unique function by delivering to dendritic cells, various materials such as M cell-derived proteins, effector proteins, toxins, and particles found in the M cell cytoplasm during infection or surveillance.

Sex differences in the acute in vivo effects of different human SP-A variants on the mouse alveolar macrophage proteome

Surfactant protein A (SP-A) is involved in lung innate immunity. Humans have two SP-A genes, SFTPA1 and SFTPA2, each with several variants. We examined the in vivo effects of treatment with specific SP-A variants on the alveolar macrophage (AM) proteome from SP-A knockout (KO) mice. KO mice received either SP-A1, SP-A2, or both. AM were collected and their proteomes examined with 2D-DIGE. We identified 90 proteins and categorized them as related to actin/cytoskeleton, oxidative stress, protease balance/chaperones, regulation of inflammation, and regulatory/developmental processes. SP-A1 and SP-A2 had different effects on the AM proteome and these effects differed between sexes. In males more changes occurred in the oxidative stress, protease/chaperones, and inflammation groups with SP-A2 treatment than with SP-A1. In females most SP-A1-induced changes were in the actin/cytoskeletal and oxidative stress groups. We conclude that after acute SP-A1 and SP-A2 treatment, sex-specific differences were observed in the AM proteomes from KO mice, and that these sex differences differ in response to SP-A1 and SP-A2. Females are more responsive to SP-A1, whereas the gene-specific differences in males were minimal. These observations not only demonstrate the therapeutic potential of exogenous SP-A, but also illustrate sex- and gene-specific differences in the response to it.

BIOLOGICAL SIGNIFICANCE

This study shows that changes occur in the alveolar macrophage proteome in response to a single in vivo treatment with exogenous SP-A1 and/or SP-A2. We demonstrate that SP-A1 and SP-A2 have different effects on the AM proteome and that sex differences exist in the response to each SP-A1 and SP-A2 gene product. This study illustrates the potential of exogenous SP-A1 and SP-A2 treatment for the manipulation of macrophage function and indicates that the specific SP-A variant used for treatment may vary with sex and with the cellular functions being modified. The observed changes may contribute to sex differences in the incidence of some lung diseases.

Antigen targeting to M cells for enhancing the efficacy of mucosal vaccines

Vaccination is one of the most successful applications of immunology and for a long time has depended on parenteral administration protocols. However, recent studies have pointed to the promise of mucosal vaccination because of its ease, economy and efficiency in inducing an immune response not only systemically, but also in the mucosal compartment where many pathogenic infections are initiated. However, successful mucosal vaccination requires the help of an adjuvant for the efficient delivery of vaccine material into the mucosa and the breaking of the tolerogenic environment, especially in oral mucosal immunization. Given that M cells are the main gateway to take up luminal antigens and initiate antigen-specific immune responses, understanding the role and characteristics of M cells is crucial for the development of successful mucosal vaccines. Especially, particular interest has been focused on the regulation of the tolerogenic mucosal microenvironment and the introduction of the luminal antigen into the lymphoid organ by exploiting the molecules of M cells. Here, we review the characteristics of M cells and the immune regulatory factors in mucosa that can be exploited for mucosal vaccine delivery and mucosal immune regulation.

Recombinant human annexin A5 inhibits proinflammatory response and improves cardiac function and survival in mice with endotoxemia

OBJECTIVES

Annexin A5 is a 35-kDa protein with high affinity binding to negatively charged phospholipids. However, its effects on sepsis are not known. Our aim was to study the effects of annexin A5 on myocardial tumor necrosis factor-α expression, cardiac function, and animal survival in endotoxemia.

DESIGN

Prospective experimental study.

SETTING

University laboratory.

SUBJECTS

Adult male C57BL/6 mice.

INTERVENTIONS

Mice were challenged with lipopolysaccharide (4 or 20 mg/kg, i.p.) to induce endotoxemia with and without recombinant human annexin A5 treatment (5 or 10 μg/kg, i.v.). Cytokine expression and cardiac function were assessed, and animal survival was monitored.

MEASUREMENTS AND MAIN RESULTS

Treatment with annexin A5 inhibited myocardial mitogen-activated protein kinase, and nuclear factor-κB activation in mice with endotoxemia. Furthermore, annexin A5-treated animals showed significant reductions in myocardial and plasma levels of tumor necrosis factor-α and interleukin-1β while cardiac function was significantly improved during endotoxemia. Additionally, 5-day animal survival was significantly improved by either an immediate or a 4-hour delayed annexin A5 treatment after lipopolysaccharide challenge. Importantly, annexin A5 dose-dependently inhibited lipopolysaccharide binding to a toll-like receptor-4/myeloid differentiation factor 2 fusion protein.

CONCLUSIONS

Annexin A5 treatment decreases cytokine expression and improves cardiac function and survival during endotoxemia. These effects of annexin A5 are mediated by its ability to inhibit lipopolysaccharide binding to toll-like receptor-4, leading to reductions in mitogen-activated protein kinase and Akt signaling. Our study suggests that annexin A5 may have therapeutic potential in the treatment of sepsis.

Microfold (M) cells: important immunosurveillance posts in the intestinal epithelium

The transcytosis of antigens across the gut epithelium by microfold cells (M cells) is important for the induction of efficient immune responses to some mucosal antigens in Peyer's patches. Recently, substantial progress has been made in our understanding of the factors that influence the development and function of M cells. This review highlights these important advances, with particular emphasis on: the host genes which control the functional maturation of M cells; how this knowledge has led to the rapid advance in our understanding of M-cell biology in the steady state and during aging; molecules expressed on M cells which appear to be used as "immunosurveillance" receptors to sample pathogenic microorganisms in the gut; how certain pathogens appear to exploit M cells to infect the host; and finally how this knowledge has been used to specifically target antigens to M cells to attempt to improve the efficacy of mucosal vaccines.

Identification of novel genes selectively expressed in the follicle-associated epithelium from the meta-analysis of transcriptomics data from multiple mouse cell and tissue populations

The follicle-associated epithelium (FAE) overlying the Peyer's patches and the microfold cells (M cells) within it are important sites of antigen transcytosis across the intestinal epithelium. Using a meta-analysis approach, we identified a transcriptional signature that distinguished the FAE from a large collection of mouse cells and tissues. A co-expressed cluster of 21 FAE-specific genes was identified, and the analysis of the transcription factor binding site motifs in their promoter regions indicated that these genes shared an underlying transcriptional programme. This cluster contained known FAE- (Anxa10, Ccl20, Psg18 and Ubd) and M-cell-specific (Gp2) genes, suggesting that the others were novel FAE-specific genes. Some of these novel candidate genes were expressed highly by the FAE and M cells (Calcb, Ces3b, Clca2 and Gjb2), and others only by the FAE (Ascl2, Cftr, Fgf15, Gpr133, Kcna1, Kcnj15, Mycl1, Pgap1 and Rps6kl). We also identified a subset of novel FAE-related genes that were induced in the intestinal epithelium after receptor activator of nuclear factor (NF)-κB ligand stimulation. These included Mfge8 which was specific to FAE enterocytes. This study provides new insight into the FAE transcriptome. Further characterization of the candidate genes identified here will aid the identification of novel regulators of cell function in the FAE.