Antibody-mediated modulation of immune responses

Patterned Antigens on DNA Origami Controls the Structure and Cellular Uptake of Immune Complexes

Immune complexes (ICs), formed via antibody (Ab)-antigen (Ag) binding, trigger diverse immune responses, which are critical for natural immunity and have uses for vaccines and immunotherapies. While IC-elicited immune responses depend on its structure, existing methods for IC synthesis produce heterogeneous assemblies, which limits control over their cellular interactions and pharmacokinetics. In this study, we demonstrate the use of DNA origami to create synthetic ICs with defined shape, size, and solubility by displaying Ags in prescribed spatial patterns. We find that Ag arrangement relative to the spatial tolerance of IgG Fab arms (∼13-18 nm) determines IC formation into "monomeric" versus "multimeric" regimes. When Ag spacing matches Fab arm tolerance, ICs are exclusively monomeric, while spacing mismatches favor the formation of multimeric ICs. Within each IC regime, parameters such as the number of Ags and Ab-Ag ratios, as well as DNA origami shape, further fine-tune IC size, shape, and Fc valency. These parameters influenced IC interactions with FcγR-expressing immune cells, with uptake by macrophages showing greater sensitivity to IC cross-linking while dendritic cells were more responsive to Ab valency. Our findings thus provide design principles for controlling the structure and cellular interactions of synthetic ICs and highlight DNA origami-scaffolded ICs as a programmable platform for investigating IC immunology and developing FcγR-targeted therapeutics and vaccines.

Dietary resveratrol improves immunity and antioxidant defense in ewes by regulating the rumen microbiome and metabolome across different reproductive stages

Introduction

Resveratrol (Res), a natural plant antitoxin polyphenol, is widely used in animal husbandry due to its antioxidant and anti-inflammatory properties, and current research has focused on humans, sows, and female mice. This study aimed to analyze the effects of dietary Res supplementation in ewes on antioxidant activity, immune responses, hormone levels, rumen microbiota and metabolites across various reproductive stages (estrus, pregnancy, and lactation).

Methods

Twenty-four healthy ewe lambs (Hu sheep, 2 months old) with a similar body weight (BW) (mean: 21.79 ± 2.09 kg) were selected and randomly divided into two groups: the control group (Con) and the Res group (Res). The Res group received 10 mg/kg Res (based on BW) in addition to their basal diet.

Results

Res increased the levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estradiol (E2) in ewes at sexual maturity (p < 0.05). Additionally, Res supplementation induced significant increases in serum glutathione peroxidase (GSH-Px), IgG, FSH, and LH levels during estrus (p < 0.05); serum IgA, IgG and IgM during pregnancy and lactation (p < 0.05); and serum LH, glucose, GSH-Px, and catalase (CAT) levels during lactation (p < 0.05). Meanwhile, serum interleukin 1β (IL-1β) (p =0.005) and cholesterol levels (p = 0.041) during the lactation stage decreased following Res supplementation. Notably, colostrum IgA, IgG, and fat concentrations were significantly higher in the Res group than in the Con group (p < 0.05). Moreover, Res altered the rumen microbiota in ewes. Specifically, the relative abundance of Prevotella (p < 0.05) during pregnancy and Rikenellaceae_RC9_gut_group (p < 0.001) during lactation were significantly increased in ewes under Res treatment. The abundance of Rikenellaceae_RC9_gut_group was positively correlated with the levels of Ig A, Ig M, E2, FSH, LH, GSH-PX, and CAT. Additionally, Res altered the activity of metabolic pathways such as progesterone-mediated oocyte maturation, the estrogen signaling pathway, ovarian steroidogenesis, and the AMPK signaling pathway, and the levels of AICAR and 2-hydroxyestradiol metabolites, both during pregnancy and lactation.

Discussion

There findings show that Res can improve health, antioxidant status, and immune activity throughout the reproductive cycle in ewes by regulating rumen microorganisms and metabolites.

Antibody modulation of B cell responses-Incorporating positive and negative feedback

Antibodies are powerful modulators of ongoing and future B cell responses. While the concept of antibody feedback has been appreciated for over a century, the topic has seen a surge in interest due to the evidence that the broadening of antibody responses to SARS-CoV-2 after a third mRNA vaccination is a consequence of antibody feedback. Moreover, the discovery that slow antigen delivery can lead to more robust humoral immunity has put a spotlight on the capacity for early antibodies to augment B cell responses. Here, we review the mechanisms whereby antibody feedback shapes B cell responses, integrating findings in humans and in mouse models. We consider the major influence of epitope masking and the diverse actions of complement and Fc receptors and provide a framework for conceptualizing the ways antigen-specific antibodies may influence B cell responses to any form of antigen, in conditions as diverse as infectious disease, autoimmunity, and cancer.

IgG sialylation occurs in B cells pre antibody secretion

Sialic acids as terminal sugar residues on cell surface or secreted proteins have many functional roles. In particular, the presence or absence of α2,6-linked sialic acid residues at the immunoglobulin G (IgG) Fc fragment can switch IgG effector functions from pro- to anti-inflammatory activity. IgG glycosylation is considered to take place inside the plasma blast/plasma cell while the molecule travels through the endoplasmic reticulum and Golgi apparatus before being secreted. However, more recent studies have suggested that IgG sialylation may occur predominantly post-antibody secretion. To what extent this extracellular IgG sialylation process contributes to overall IgG sialylation remains unclear, however. By generating bone marrow chimeric mice with a B cell-specific deletion of ST6Gal1, the key enzyme required for IgG sialylation, we now show that sialylation of the IgG Fc fragment exclusively occurs within B cells pre-IgG secretion. We further demonstrate that B cells expressing ST6Gal1 have a developmental advantage over B cells lacking ST6Gal1 expression and thus dominate the plasma cell pool and the resulting serum IgG population in mouse models in which both ST6Gal1-sufficient and -deficient B cells are present.

Autoantigenic Peptide and Immunomodulator Codelivery System for Rheumatoid Arthritis Treatment by Reestablishing Immune Tolerance

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by abnormal activation of CD4+ T cells and an imbalance of T helper 17 (Th17) and regulatory T (Treg) cells. Tolerogenic therapy via administration of self-antigens is a promising strategy for RA treatment, but delivery of autoantigens alone may exacerbate disease conditions. Current studies indicated that codelivery of autoantigens with immunomodulators can lead to a more tolerogenic immune response. Here, we constructed an autoantigen type II collagen peptide (CII250-270)- and immunomodulator leflunomide (LEF)-coloaded phosphatidylserine liposome vaccine (CII250-270-LEF-PSL) for RA treatment via induction of tolerant dendritic cells (tolDC) for further activation of Treg cells. The in vivo results showed that CII250-270-LEF-PSL can effectively induce tolDC, regulate the balance of Th1/Th2 and Th17/Treg, and reduce the secretion of pro-inflammatory cytokines (IFN-γ, IL-1β, and IL-17A) and IgG antibodies to inhibit synovial inflammation and bone erosion. Furthermore, our study also suggested that LEF regulated Th1 cell differentiation by inhibiting the activation of the JAK1/STAT1 signaling pathway, further alleviating RA. Overall, this work proved that the combination of autoantigenic peptides and immunomodulators was a promising modality for RA treatment by reestablishing antigen-specific immune tolerance, which also inspired additional insights into the development of combination therapies for the tolerability of RA.

Phagocytosis

One hundred years have passed since the death of Élie Metchnikoff (1845-1916). He was the first to observe the uptake of particles by cells and realized the importance of this process, named phagocytosis, for the host response to injury and infection. He also was a strong advocate of the role of phagocytosis in cellular immunity, and with this, he gave us the basis for our modern understanding of inflammation and the innate immune response. Phagocytosis is an elegant but complex process for the ingestion and elimination of pathogens, but it is also important for the elimination of apoptotic cells and hence fundamental for tissue homeostasis. Phagocytosis can be divided into four main steps: (i) recognition of the target particle, (ii) signaling to activate the internalization machinery, (iii) phagosome formation, and (iv) phagolysosome maturation. In this chapter, we present a general view of our current knowledge on phagocytosis performed mainly by professional phagocytes through antibody and complement receptors and discuss aspects that remain incompletely understood.

Analyzing Fcγ-Receptor Interactions on Monocytes with the Proximity Ligation Assay (PLA)

Proximity ligation assays (PLA) enable the detection and characterization of protein interactions independent of protein abundance or genetic modifications. This technique exploits both antibody and DNA-binding features, providing high selectivity and sensitivity for protein recognition and visualization of single-protein molecules with high spatial accuracy. Here, we describe the general procedure for a direct PLA on splenic monocytes to analyze FcγRIIb homodimerization. However, this method can be applied to other cells and receptors of interest.

Dietary resveratrol supplementation on growth performance, immune function and intestinal barrier function in broilers challenged with lipopolysaccharide

This study discusses the effects of resveratrol (RES) on the productive performance, immune function and intestinal barrier function of broiler chickens challenged with lipopolysaccharide (LPS). Two hundred and forty 1-day-old male Arbor Acres broilers were randomly divided into 4 groups of 6 replicates each, with 10 broilers per replicate. This experiment used a 2 × 2 factorial design with dietary factors (basal diets or basal diets supplemented with 400 mg/kg RES were administered from d 1 to 21) and stress factors (intraperitoneal injection of 0.5 mg/kg BW of saline or LPS at 16, 18 and 20 d of age). The results showed that LPS challenge had a significant adverse effect on average daily gain (ADG) in broilers at 16 to 21 d of age (P < 0.05), whereas the addition of RES to the diet inhibited the LPS-induced decrease in ADG (P < 0.05). RES also alleviated LPS-induced immune function damage in broilers, which was manifested by the decrease of spleen index (P < 0.05) and the recovery of serum immunoglobulin M and ileal secretory immunoglobulin A content (P < 0.05). The LPS challenge also disrupts intestinal barrier function and inflammation, and RES mitigates these adverse effects in different ways. RES attenuated LPS-induced reduction of villus height in the jejunum and ileum of broilers (P < 0.05). LPS also caused an abnormal increase in plasma D-lactic acid levels in broilers (P < 0.05), which was effectively mitigated by RES (P < 0.05). LPS challenge resulted in a significant decrease in mRNA expression of occludin in the intestinal mucosa (P < 0.05), which was mitigated by the addition of RES (P < 0.05). RES significantly decreased the mRNA expression of toll-like receptor 4, nuclear factor kappa-B and tumor necrosis factor alpha in the ileum tissue stimulated by LPS (P < 0.05). Taken together, this study shows that RES exerts its beneficial effect on broilers challenged with LPS by alleviating immune function damage, relieving intestinal inflammation and barrier damage, and thus improving growth performance.

Combined Nano-Vector Mediated-Transfer to Suppress HIV-1 Infection with Targeted Antibodies in-vitro

Introduction

Broadly neutralizing antibodies (bNAbs) have the ability to neutralize a considerable breadth of genetically diverse human immunodeficiency virus (HIV) strains. Passive immunization can potentially provide protection against HIV infection in animal models. However, the direct antibody infusion effect is limited due to the short half-life and deficient immunogenicity of the antibody. As an alternative strategy, we propose the use of nano viral vectors, specifically the adeno-associated virus (AAV), to continuously and systematically produce bNAbs against HIV.

Methods

Plasmids expressing bNAbs PG9, PG16, 10E8, and NIH45-46 antibodies were constructed, targeting three different epitopes of HIV. Additionally, the bNAbs gene mediated by rAAV8 was administered to generate long-term expression with a single injection. We established both single and combined immunization groups. The neutralizing activity of antibodies expressed in mice sera was subsequently evaluated.

Results

The expression of bNAbs in BALB/c mice can last for >24 weeks after a single intramuscular injection of rAAV8. Further studies show that neutralization of the HIV pseudovirus by sera from co-immunized mice with rAAV8 expressing 10E8 and PG16 was enhanced compared with mice immunized with 10E8 or PG16 alone.

Conclusion

The prolonged expression of neutralizing antibodies can be maintained over long periods in BALB/c mice. This combined immunization is a promising candidate strategy for HIV treatment.

Polyfunctional antibodies: a path towards precision vaccines for vulnerable populations

Vaccine efficacy determined within the controlled environment of a clinical trial is usually substantially greater than real-world vaccine effectiveness. Typically, this results from reduced protection of immunologically vulnerable populations, such as children, elderly individuals and people with chronic comorbidities. Consequently, these high-risk groups are frequently recommended tailored immunisation schedules to boost responses. In addition, diverse groups of healthy adults may also be variably protected by the same vaccine regimen. Current population-based vaccination strategies that consider basic clinical parameters offer a glimpse into what may be achievable if more nuanced aspects of the immune response are considered in vaccine design. To date, vaccine development has been largely empirical. However, next-generation approaches require more rational strategies. We foresee a generation of precision vaccines that consider the mechanistic basis of vaccine response variations associated with both immunogenetic and baseline health differences. Recent efforts have highlighted the importance of balanced and diverse extra-neutralising antibody functions for vaccine-induced protection. However, in immunologically vulnerable populations, significant modulation of polyfunctional antibody responses that mediate both neutralisation and effector functions has been observed. Here, we review the current understanding of key genetic and inflammatory modulators of antibody polyfunctionality that affect vaccination outcomes and consider how this knowledge may be harnessed to tailor vaccine design for improved public health.

Myocardial ischemia-reperfusion injury; Molecular mechanisms and prevention

Cardiovascular diseases are one of the leading causes of mortality in developed countries. Among cardiovascular disorders, myocardial infarction remains a life-threatening problem predisposing to the development and progression of ischemic heart failure. Ischemia/reperfusion (I/R) injury is a critical cause of myocardial injury. In recent decades, many efforts have been made to find the molecular and cellular mechanisms underlying the development of myocardial I/R injury and post-ischemic remodeling. Some of these mechanisms are mitochondrial dysfunction, metabolic alterations, inflammation, high production of ROS, and autophagy deregulation. Despite continuous efforts, myocardial I/R injury remains a major challenge in medical treatments of thrombolytic therapy, heart disease, primary percutaneous coronary intervention, and coronary arterial bypass grafting. The development of effective therapeutic strategies to reduce or prevent myocardial I/R injury is of great clinical significance.

Residue interaction network and molecular dynamics simulation study on the binding of S239D/I332E Fc variant with enhanced affinity to FcγRIIIa receptor

Engineering of Fc has been adapted as an efficient method for enhanced or reduced affinity towards Fc receptors in the development of therapeutic antibodies. S239D/I332E mutation of Fc induces approximately two logs greater affinity to the FcγRIIIa receptor and has been extensively employed in various Fc engineering studies. It is known that the mutation gives rise to the formation of salt bridges between the mutated residues of Fc and FcγRIIIa, but the overall effect of the mutation in the binding interface of the Fc-FcγRIIIa complex is still unclear. In this study, the molecular interactions in the binding interface of mutant Fc and FcγRIIIa were analyzed and compared with those of wild-type Fc binding through residue interaction network (RIN) analysis and molecular dynamics (MD) simulation. RIN analysis identified specific molecular interactions and Hub residues in the interfaces, and their numbers were increased by introducing the mutation, with maintaining most of the molecular interactions in the wild-type complex. MD simulation study revealed that the numbers of stable electrostatic interactions and stable Hub residues in the mutant complex were higher than those in the wild-type complex. The introduced mutations were shown to form further charge-charge attractive interactions in addition to the identified salt bridges without generating any repulsive interactions. These results are expected to provide further structural insight into Fc variants' design based on the S239D/I332E mutation.

Immunomodulatory Effects of Chicken Broth and Histidine Dipeptides on the Cyclophosphamide-Induced Immunosuppression Mouse Model

The carnosine and anserine, which represent histidine dipeptides (HD), are abundant in chicken broth (CB). HD are endogenous dipeptide that has excellent antioxidant and immunomodulatory effects. The immunomodulatory effect of CB hydrolysate (CBH) and HD in cyclophosphamide (CTX)-induced immunosuppressed mice was examined in this study. CBH and HD were given to mice via oral gavage for 15 days, accompanied by intraperitoneal CTX administration to induce immunosuppression. CBH and HD treatment were observed to reduce immune organ atrophy (p < 0.05) and stimulate the proliferation of splenic lymphocytes (p < 0.05) while improving white blood cell, immunoglobulin M (IgM), IgG, and IgA levels (p < 0.05). Moreover, CBH and HD strongly stimulated interleukin-2 (IL-2) and interferon-gamma (IFN-γ) production by up-regulating IL-2 and IFN-γ mRNA expression (p < 0.05) while inhibiting interleukin-10 (IL-10) overproduction and IL-10 mRNA expression (p < 0.05). In addition, CBH and HD prevented the inhibition of the nitric oxide (NP)/cyclic guanosine monophosphate-cyclic adenosine monophosphate (cGMP-cAMP)/protein kinase A (PKA) signaling pathway (p < 0.05). These results indicate that CBH and HD have the potential to prevent immunosuppression induced by CTX. Our data demonstrate that CBH can effectively improve the immune capacity of immunosuppressed mice similar to the same amount of purified HD, which indicates that CBH plays its role through its own HD.

Phytogenic feed additives alleviate pathogenic Escherichia coli-induced intestinal damage through improving barrier integrity and inhibiting inflammation in weaned pigs

Background

This study was conducted to investigate the effects of each phytogenic feed additive (PFA; PFA1, bitter citrus extract; PFA2, a microencapsulated blend of thymol and carvacrol; PFA3, a mixture of bitter citrus extract, thymol, and carvacrol; PFA4, a premixture of grape seed, grape marc extract, green tea, and hops; PFA5, fenugreek seed powder) on the growth performance, nutrient digestibility, intestinal morphology, and immune response in weaned pigs infected with Escherichia coli (E. coli).

Results

A total of 63 4-week-old weaned pigs were placed in individual metabolic cages and assigned to seven treatment groups. The seven treatments were as follows: 1) NC; basal diet without E. coli challenge, 2) PC; basal diet with E. coli challenge, 3) T1; PC + 0.04% PFA1, 4) T2; PC + 0.01% PFA2, 5) T3; PC + 0.10% PFA3, 6) T4; PC + 0.04% PFA4, 7) T5; PC + 0.10% PFA5. The experiments lasted in 21 d, including 7 d before and 14 d after the first E. coli challenge. In the E. coli challenge treatments, all pigs were orally inoculated by dividing a total of 10 mL of E. coli F18 for 3 consecutive days. The PFA-added groups significantly increased (P < 0.05) average daily gain and feed efficiency and decreased (P < 0.05) the fecal score at d 0 to 14 post-inoculation (PI). Tumor necrosis factor α was significantly lower (P < 0.05) in the PFA-added groups except for T1 in d 14 PI compared to the PC treatment. The T3 had a higher (P < 0.05) immunoglobulin G and immunoglobulin A concentration compared to the PC treatment at d 7 PI. Also, T3 showed significantly higher (P < 0.05) villus height:crypt depth and claudin 1 expression in ileal mucosa, and significantly down-regulated (P < 0.05) the expression of calprotectin compared to the PC treatment.

Conclusions

Supplementation of PFA in weaned pigs challenged with E. coli alleviated the negative effects of E. coli and improved growth performance. Among them, the mixed additive of bitter citrus extract, thymol, and carvacrol showed the most effective results, improving immune response, intestinal morphology, and expression of tight junctions.

The kinetics of IgG subclasses and contributions to neutralizing activity against SARS-CoV-2 wild-type strain and variants in healthy adults immunized with inactivated vaccine

Neutralizing antibody is an important indicator of vaccine efficacy, of which IgG is the main component. IgG can be divided into four subclasses. Up to now, studies analysing the humoral response to SARS‐CoV‐2 vaccination have mostly focused on measuring total IgG, and the contribution of specific IgG subclasses remains elusive. The aim of this study is to investigate the kinetics of neutralizing antibodies and IgG subclasses, and to explore their relationships in people vaccinated with inactivated COVID‐19 vaccine. We conducted a prospective cohort study in 174 healthy adults aged 18–59 years old who were administrated 2 doses of CoronaVac 14 days apart and a booster dose 1 year after the primary immunization, and followed up for 15 months. Blood samples were collected at various time points after primary and booster immunization. We used live SARS‐CoV‐2 virus neutralizing assay to determine neutralizing ability against the wild‐type strain and 4 variants (Beta, Gamma, Delta and Omicron) and ELISA to quantify SARS‐CoV‐2 RBD‐specific IgG subclasses. The results showed that the 2‐dose primary immunization only achieved low neutralizing ability, while a booster shot can significantly enhance neutralizing ability against the wild‐type strain, Beta, Gamma, Delta and Omicron variants. IgG1 and IgG3 were the most abundant serum antibodies, and IgG2 and IgG4 were hardly detected at any time. The ratio of IgG1/IgG3 was positively associated with the neutralization ability. The underlying mechanism requires further exploration.

IgG targeting distinct seasonal coronavirus- conserved SARS-CoV-2 spike subdomains correlates with differential COVID-19 disease outcomes

Despite SARS-CoV-2 being a "novel" virus, early detection of anti-spike IgG in severe COVID-19 patients may be caused by the amplification of humoral memory responses against seasonal coronaviruses. Here, we examine this phenomenon by characterizing anti-spike IgG responses in non-hospitalized convalescent individuals across a spectrum of COVID-19 severity. We observe that disease severity positively correlates with anti-spike IgG levels, IgG cross-reactivity against other betacoronaviruses (β-CoVs), and FcγR activation. Analysis of IgG targeting β-CoV-conserved and non-conserved immunodominant epitopes within the SARS-CoV-2 spike protein revealed epitope-specific relationships: IgG targeting the conserved heptad repeat (HR) 2 region significantly correlates with milder disease, while targeting the conserved S2'FP region correlates with more severe disease. Furthermore, a lower HR2-to-S2'FP IgG-binding ratio correlates with greater disease severity, with ICU-hospitalized COVID-19 patients showing the lowest HR2/S2'FP ratios. These findings suggest that HR2/S2'FP IgG profiles may predict disease severity and offer insight into protective versus deleterious humoral recall responses.

Personalized Therapeutic Strategies in the Management of Osteoporosis in Patients with Autoantibody-Positive Rheumatoid Arthritis

Bone mineral density (BMD) reduction and fragility fractures still represent a major source of morbidity in rheumatoid arthritis (RA) patients, despite adequate control of the disease. An increasing number of clinical and experimental evidence supports the role of autoantibodies, especially anti-citrullinated protein antibodies (ACPAs), in causing localized and generalised bone loss in ways that are both dependent on and independent of inflammation and disease activity. The human receptor activator of nuclear factor kappa B and its ligand—the so-called RANK-RANKL pathway—is known to play a key role in promoting osteoclasts’ activation and bone depletion, and RANKL levels were shown to be higher in ACPA-positive early untreated RA patients. Thus, ACPA-positivity can be considered a specific risk factor for systemic and periarticular bone loss. Through the inhibition of the RANK-RANKL system, denosumab is the only antiresorptive drug currently available that exhibits both a systemic anti-osteoporotic activity and a disease-modifying effect when combined with conventional synthetic or biologic disease-modifying anti-rheumatic drugs (DMARDs). Thus, the combination of DMARD and anti-RANKL therapy could be beneficial in the prevention of fragility fractures and structural damage in the subset of RA patients at risk of radiographic progression, as in the presence of ACPAs.

Microvascular Inflammation of the Renal Allograft: A Reappraisal of the Underlying Mechanisms

Antibody-mediated rejection (ABMR) is associated with poor transplant outcomes and was identified as a leading cause of graft failure after kidney transplantation. Although the hallmark histological features of ABMR (ABMRh), i.e., microvascular inflammation (MVI), usually correlate with the presence of anti-human leukocyte antigen donor-specific antibodies (HLA-DSAs), it is increasingly recognized that kidney transplant recipients can develop ABMRh in the absence of HLA-DSAs. In fact, 40-60% of patients with overt MVI have no circulating HLA-DSAs, suggesting that other mechanisms could be involved. In this review, we provide an update on the current understanding of the different pathogenic processes underpinning MVI. These processes include both antibody-independent and antibody-dependent mechanisms of endothelial injury and ensuing MVI. Specific emphasis is placed on non-HLA antibodies, for which we discuss the ontogeny, putative targets, and mechanisms underlying endothelial toxicity in connection with their clinical impact. A better understanding of these emerging mechanisms of allograft injury and all the effector cells involved in these processes may provide important insights that pave the way for innovative diagnostic tools and highly tailored therapeutic strategies.

Detection and functional resolution of soluble immune complexes by an FcγR reporter cell panel

Fc-gamma receptor (FcγR) activation by soluble IgG immune complexes (sICs) represents a major mechanism of inflammation in certain autoimmune diseases such as systemic lupus erythematosus (SLE). A robust and scalable test system allowing for the detection and quantification of sIC bioactivity is missing. We developed a comprehensive reporter cell panel detecting activation of FcγRs. The reporter cell lines were integrated into an assay that enables the quantification of sIC reactivity via ELISA or a faster detection using flow cytometry. This identified FcγRIIA(H) and FcγRIIIA as the most sIC-sensitive FcγRs in our test system. Reaching a detection limit in the very low nanomolar range, the assay proved also to be sensitive to sIC stoichiometry and size reproducing for the first time a complete Heidelberger-Kendall curve in terms of immune receptor activation. Analyzing sera from SLE patients and mouse models of lupus and arthritis proved that sIC-dependent FcγR activation has predictive capabilities regarding severity of SLE disease. The assay provides a sensitive and scalable tool to evaluate the size, amount, and bioactivity of sICs in all settings.

Allorecognition and the spectrum of kidney transplant rejection

Detection of mismatched human leukocyte antigens by adaptive immune cells is considered as the main cause of transplant rejection, leading to either T-cell mediated rejection or antibody-mediated rejection. This canonical view guided the successful development of immunosuppressive therapies and shaped the diagnostic Banff classification for kidney transplant rejection that is used in clinics worldwide. However, several observations have recently emerged that question this dichotomization between T-cell mediated rejection and antibody-mediated rejection, related to heterogeneity in the serology, histology, and prognosis of the rejection phenotypes. In parallel, novel insights were obtained concerning the dynamics of donor-specific anti-human leukocyte antigen antibodies, the immunogenicity of donor-recipient non-human leukocyte antigen mismatches, and the autoreactivity against self-antigens. Moreover, the potential of innate allorecognition was uncovered, as exemplified by natural killer cell-mediated microvascular inflammation through missing self, and by the emerging evidence on monocyte-driven allorecognition. In this review, we highlight the gaps in the current classification of rejection, provide an overview of the expanding insights into the mechanisms of allorecognition, and critically appraise how these could improve our understanding and clinical approach to kidney transplant rejection. We argue that consideration of the complex interplay of various allorecognition mechanisms can foster a more integrated view of kidney transplant rejection and can lead to improved risk stratification, targeted therapies, and better outcome after kidney transplantation.

Immunomodulatory effects of selenium-enriched peptides from soybean in cyclophosphamide-induced immunosuppressed mice

In this study, selenium-enriched soybean peptides (<3 kDa, named Se-SPep) was isolated and purified from the selenium-enriched soybean protein (Se-SPro) hydrolysate by ultrafiltration. The in-vivo immunomodulatory effects of Se-SPep were investigated in cyclophosphamide-induced immunosuppressed mice. Se-SPep treatment could alleviate the atrophy of immune organs and weight loss observed in immunosuppressive mice. Besides, Se-SPep administration could dramatically improve total protein, albumin, white blood cell, immunoglobulin (Ig) M, IgG, and IgA levels in blood. Moreover, Se-SPep strongly stimulated interleukin-2 (IL-2), interferon-gamma (IFN-γ), nitric oxide (NO), and cyclic guanosine monophosphate productions by up-regulating mRNA expressions of IL-2, IFN-γ, and inducible NO synthase in spleen tissue. Furthermore, Se-SPep exhibits more effective immunomodulatory activity compared to Se-SPro and SPep. In conclusion, Se-SPep could effectively enhance the immune capacity of immunosuppressive mice. These findings confirm Se-SPep is an effective immunomodulator with potential application in functional foods or dietary supplements.

Influenza Immunization in the Context of Preexisting Immunity

Although we develop influenza immunity from an early age, it is insufficient to prevent future infection with antigenically novel strains. One proposed way to generate long-term protective immunity against a broad range of influenza virus strains is to boost responses to the conserved epitopes on the hemagglutinin, the major surface glycoprotein on the influenza virus. Influenza-specific humoral immunity comprises a large fraction of the overall immune memory in humans, and it has been long recognized that preexisting immunity to influenza shapes the response to subsequent influenza infections and vaccinations. However, the mechanisms by which preexisting immunity modulates the response to influenza vaccination are still not completely understood. Using a set of mathematical models, we explore several hypotheses that may contribute to diminished boosting of antibodies to conserved epitopes after repeated vaccinations.

Microfluidics applications for high-throughput single cell sequencing

The inherent heterogeneity of individual cells in cell populations plays significant roles in disease development and progression, which is critical for disease diagnosis and treatment. Substantial evidences show that the majority of traditional gene profiling methods mask the difference of individual cells. Single cell sequencing can provide data to characterize the inherent heterogeneity of individual cells, and reveal complex and rare cell populations. Different microfluidic technologies have emerged for single cell researches and become the frontiers and hot topics over the past decade. In this review article, we introduce the processes of single cell sequencing, and review the principles of microfluidics for single cell analysis. Also, we discuss the common high-throughput single cell sequencing technologies along with their advantages and disadvantages. Lastly, microfluidics applications in single cell sequencing technology for the diagnosis of cancers and immune system diseases are briefly illustrated.

Humoral immune responses during SARS-CoV-2 mRNA vaccine administration in seropositive and seronegative individuals

BACKGROUND

The global pandemic of coronavirus disease 2019 (COVID-19) is caused by infection with the SARS-CoV-2 virus. Currently, there are three approved vaccines against SARS-CoV-2 in the USA, including two based on messenger RNA (mRNA) technology that has demonstrated high vaccine efficacy. We sought to characterize humoral immune responses, at high resolution, during immunization with the BNT162b2 (Pfizer-BioNTech) vaccine in individuals with or without prior history of natural SARS-CoV-2 infection.

METHODS

We determined antibody responses after each dose of the BNT162b2 SARS-CoV-2 vaccine in individuals who had no prior history of SARS-CoV-2 infection (seronegative) and individuals that had previous viral infection 30-60 days prior to first vaccination (seropositive). To do this, we used both an antibody isotype-specific multiplexed bead-based binding assays targeting multiple SARS-CoV-2 viral protein antigens and an assay that identified potential SARS-CoV-2 neutralizing antibody levels. Moreover, we mapped antibody epitope specificity after immunization using SARS-CoV-2 spike protein peptide arrays.

RESULTS

Antibody levels were significantly higher after a single dose in seropositive individuals compared to seronegative individuals and were comparable to levels observed in seronegative individuals after two doses. While IgG was boosted by vaccination for both seronegative and seropositive individuals, only seronegative individuals had increased IgA or IgM antibody titers after primary immunization. We identified immunodominant peptides targeted on both SARS-CoV-2 spike S1 and S2 subunits after vaccination.

CONCLUSION

These findings demonstrated the antibody responses to SARS-CoV-2 immunization in seropositive and seronegative individuals and provide support for the concept of using prior infection history as a guide for the consideration of future vaccination regimens. Moreover, we identified key epitopes on the SARS-CoV-2 spike protein that are targeted by antibodies after vaccination that could guide future vaccine and immune correlate development.

COBRA™: a highly potent conditionally active T cell engager engineered for the treatment of solid tumors

Conditionally active COBRA™ (COnditional Bispecific Redirected Activation) T cell engagers are engineered to overcome the limitations of inherently active first-generation T cell engagers, which are unable to discern between tumor and healthy tissues. Designed to be administered as prodrugs, COBRAs target cell surface antigens upon administration, but engage T cells only after they are activated within the tumor microenvironment (TME). This allows COBRAs to be preferentially turned on in tumors while safely remaining inactive in healthy tissue. Here, we describe the development of the COBRA design and the characterization of these conditionally active T cell engagers. Upon administration COBRAs are engineered to bind to tumor-associated antigens (TAAs) and serum albumin (to extend their half-life in circulation), but are inhibited from interacting with the T cell receptor complex signaling molecule CD3. In the TME, a matrix metalloproteinase (MMP)-mediated linker cleavage event occurs within the COBRA construct, which rearranges the molecule, allowing it to co-engage TAAs and CD3, thereby activating T cells against the tumor. COBRAs are conditionally activated through cleavage with MMP9, and once active are highly potent, displaying sub-pM EC₅₀s in T cell killing assays. Studies in tumor-bearing mice demonstrate COBRA administration completely regresses established solid tumor xenografts. These results strongly support the further characterization of the novel COBRA design in preclinical development studies.

Effect of fennel essential oil on performance, serum biochemistry, immunity, ileum morphology and microbial population, and meat quality of broiler chickens fed corn or wheat-based diet

1. The effect of Foeniculi aetheroleum essential oil (EO) on growth performance, nutrient utilisation, serum biochemistry, immune response, ileum morphology, microbial population and meat quality of broiler chickens fed a corn- or wheat-based diet were determined.2. A total of 360 broiler chickens were arranged in a 2 × 2 factorial assay in a completely randomised design with six replicates and 15 birds per experimental unit. Birds were fed corn- or wheat-based diets supplemented with (200 mg/kg) or without fennel EO.3. Birds fed wheat-based diets had lower BWG and FCR during grower period and lower FI during finisher period as compared to those fed corn-based diet (P < 0.05) whereas addition of fennel EO decreased chickens BWG during finisher period and EPEF, both in wheat or in corn-based diets. Dietary treatments had no effect on serum glucose, triglyceride, cholesterol, LDL-cholesterol, AST, ALT, ALP, and MDA concentrations (P < 0.05).4. Antibody titres against avian influenza and sheep red blood cell antibody titres, crude protein and crude fat utilisation, villus height, crypt depth and epithelium thickness were not influenced by dietary treatments (P > 0.05). Inclusion of Fennel EO to the corn-based diet resulted in greater villus width and villus surface area while it reduced lamina propria thickness (P < 0.05). Fennel EO reduced ileal E. coli and Lactobacillus spp. populations (P < 0.05). Dietary treatments had no significant effect on meat pH, cooking loss, drip loss, crude protein, crude fat content and cholesterol concentration of breast and thigh meat, total phenolic and MDA concentrations, and breast meat sensory parameters (P > 0.05).5. These results showed that addition of fennel EO to wheat-based diets had a negative effect on chicken growth performance variables and decreased gut E. coli populations. However, immunity, meat quality and nutrient utilisation were not affected by dietary treatments.

Jackfruit (Artocarpus heterophyllus Lam.) oligopeptides regulate immune responses via Th cell stimulation, cytokine secretion and antibody production

This study aimed to observe the immunomodulatory effects of oligopeptides derived from jackfruit (Artocarpus heterophyllus Lam.) (JOPs). 200 female BALB/c mice in five groups were respectively given deionized water (control), whey protein (0.20 g per kg body weight (BW)) and JOPs at doses of 0.20, 0.40, and 0.80 g per kg BW by intragastric administration on a daily basis. 7 tests were conducted to determine the immunomodulatory effects of JOPs on immune organ indexes, cellular and humoral immune responses, macrophage phagocytosis, and natural killer (NK) cell activity. Spleen T lymphocyte sub-populations and serum cytokine and immunoglobulin levels were tested to study how JOPs improved the immune system. We found that JOPs could significantly enhance innate and adaptive immune responses in mice by the improvement of cell-mediated and humoral immunity, macrophage phagocytosis capacity and NK cell activity. The immunomodulatory effects may be based on increased T and Th cell percentages, serum interleukin (IL)-1α, IL-10, tumor necrosis factor (TNF)-α, production of immunoglobulin (Ig) M, IgG, and IgA, and depressed interferon (IFN)-γ secretion. These results suggest that dietary JOPs could be valuable as potential immunomodulators.

Non-Specific Antibodies Induce Lysosomal Activation in Atlantic Salmon Macrophages Infected by Piscirickettsia salmonis

Piscirickettsia salmonis, an aggressive intracellular pathogen, is the etiological agent of salmonid rickettsial septicemia (SRS). This is a chronic multisystemic disease that generates high mortalities and large losses in Chilean salmon farming, threatening the sustainability of the salmon industry. Previous reports suggest that P. salmonis is able to survive and replicate in salmonid macrophages, inducing an anti-inflammatory environment and a limited lysosomal response that may be associated with host immune evasion mechanisms favoring bacterial survival. Current control and prophylaxis strategies against P. salmonis (based on the use of antibiotics and vaccines) have not had the expected success against infection. This makes it urgent to unravel the host-pathogen interaction to develop more effective therapeutic strategies. In this study, we evaluated the effect of treatment with IgM-beads on lysosomal activity in Atlantic salmon macrophage-enriched cell cultures infected with P. salmonis by analyzing the lysosomal pH and proteolytic ability through confocal microscopy. The impact of IgM-beads on cytotoxicity induced by P. salmonis in infected cells was evaluated by quantification of cell lysis through release of Lactate Dehydrogenase (LDH) activity. Bacterial load was determined by quantification of 16S rDNA copy number by qPCR, and counting of colony-forming units (CFU) present in the extracellular and intracellular environment. Our results suggest that stimulation with antibodies promotes lysosomal activity by lowering lysosomal pH and increasing the proteolytic activity within this organelle. Additionally, incubation with IgM-beads elicits a decrease in bacterial-induced cytotoxicity in infected Atlantic salmon macrophages and reduces the bacterial load. Overall, our results suggest that stimulation of cells infected by P. salmonis with IgM-beads reverses the modulation of the lysosomal activity induced by bacterial infection, promoting macrophage survival and bacterial elimination. This work represents a new important evidence to understand the bacterial evasion mechanisms established by P. salmonis and contribute to the development of new effective therapeutic strategies against SRS.

Anti-Tyro3 IgG Associates with Disease Activity and Reduces Efferocytosis of Macrophages in New-Onset Systemic Lupus Erythematosus

Background

Systemic lupus erythematosus (SLE) is a disease characterized by the production of a large number of autoantibodies. Defected phagocytosis of macrophage plays an important role in innate immunity in the pathogenesis of SLE. Tyro3 is a receptor responsible for the recognition of apoptotic cells during efferocytosis by macrophages. To investigate the role of Tyro3 receptor in macrophages' efferocytosis of apoptotic cells in SLE, we aimed to reveal the clinical relevance and impact of Tyro3 autoantibody on SLE.

Methods

The serum levels of IgG-type autoantibody against Tyro3 receptor were detected in new-onset, treatment-naïve SLE patients (n = 70), rheumatoid arthritis (RA) (n = 24), primary Sjögren's Syndrome (pSS) (n = 21), and healthy controls (HCs) (n = 70) using enzyme-linked immunosorbent assay (ELISA). The effects of purified Tyro3 autoantibody from SLE patients on the efferocytosis of human monocyte-derived macrophages were measured by flow cytometry and immunofluorescence.

Results

The serum levels of IgG-type autoantibody against Tyro3 receptor were significantly elevated in patients with SLE compared to RA, pSS, and HCs (all p < 0.0001). The levels of anti-Tyro3 IgG were positively associated with the SLE disease activity index (SLEDAI) score (r = 0.254, p = 0.034), erythrocyte sedimentation rate (ESR) (r = 0.430, p < 0.001), C-reactive protein (CRP) (r = 0.246, p = 0.049), and immunoglobulin G (IgG) (r = 0.408, p = 0.001) and negatively associated with haemoglobin (Hb) (r = -0.294, p = 0.014). ROC curves illustrated that the anti-Tyro3 antibody could differentiate patients with SLE from HCs. Furthermore, flow cytometry and immunofluorescence demonstrated that purified anti-Tyro3 IgG inhibited the efferocytosis of macrophages (p = 0.004 and 0.044, respectively) compared with unconjugated human IgG.

Conclusions

These observations indicated that autoantibody against Tyro3 was associated with disease activity and could impair efferocytosis of macrophages. It might be a potential novel disease biomarker and might be involved in the pathogenesis of SLE.

Chemical synthesis and immunological evaluation of entirely carbohydrate conjugate Globo H-PS A1

An anticancer, entirely carbohydrate conjugate, Globo H-polysaccharide A1 (Globo H-PS A1), was chemically prepared and immunologically evaluated in C57BL/6 mice. Tumor associated carbohydrate antigen Globo H hexasaccharide was synthesized in an overall 7.8% yield employing a convergent [3 + 3] strategy that revealed an anomeric aminooxy group used for conjugation to oxidized PS A1 via an oxime linkage. Globo H-PS A1, formulated with adjuvants monophosphoryl lipid A and TiterMax® Gold. After immunization an antigen specific immune response was observed in ELISA with anti-Globo H IgG/IgM antibodies. Specificity of the corresponding antibodies was determined by FACS showing cell surface binding to Globo H-positive cancer cell lines MCF-7 and OVCAR-5. The anti-Globo H antibodies also exhibited complement-dependent cellular cytotoxicity against MCF-7 and OVCAR-5 cells.

IgG-mediated suppression of antibody responses: Hiding or snatching epitopes?

Antibodies forming a complex with antigen in vivo can dramatically change the antibody response to this antigen. In some situations, the response will be a 100-fold stronger than in animals immunized with antigen alone, and in other situations, the response will be completely suppressed. IgG is known to suppress the antibody response, for example to erythrocytes, and this is used clinically in Rhesus prophylaxis. The mechanism behind IgG-mediated immune suppression is still not understood. Here, we will review studies performed in experimental animal models and discuss the various hypotheses put forward to explain the profound suppressive effect of IgG. We conclude that an exclusive role for negative regulation of B cells through FcγRIIB, increased clearance of erythrocytes from the circulation or complement-mediated lysis is unlikely. Epitope masking, where IgG hides the epitope from B cells, or trogocytosis, where IgG removes the epitope from the erythrocyte, is compatible with many observations. These two mechanisms are not mutually exclusive. Moreover, it cannot be ruled out that clearance, in combination with other mechanisms, plays a role.

Human Fcγ-receptor IIb modulates pathogen-specific versus self-reactive antibody responses in lyme arthritis

Pathogen-specific antibody responses need to be tightly regulated to generate protective but limit self-reactive immune responses. While loss of humoral tolerance has been associated with microbial infections, the pathways involved in balancing protective versus autoreactive antibody responses in humans are incompletely understood. Studies in classical mouse model systems have provided evidence that balancing of immune responses through inhibitory receptors is an important quality control checkpoint. Genetic differences between inbred mouse models and the outbred human population and allelic receptor variants not present in mice; however, argue for caution when directly translating these findings to the human system. By studying Borrelia burgdorferi infection in humanized mice reconstituted with human hematopoietic stem cells from donors homozygous for a functional or a non-functional FcγRIIb allele, we show that the human inhibitory FcγRIIb is a critical checkpoint balancing protective and autoreactive immune responses, linking infection with induction of autoimmunity in the human immune system.

Mouse Models of Rheumatoid Arthritis for Studies on Immunopathogenesis and Preclinical Testing of Fc Receptor-Targeting Biologics

<b><i>Background:</i></b> Rheumatoid arthritis (RA) is a chronic autoimmune disease that causes inflammation, swelling, and pain in the joints and involves systemic complications. Mouse models of RA have been extensively used to model the pathogenesis of RA and to develop effective therapies. Although many components of the immune system have been studied in these models, the role of crystallizable fragment (Fc) gamma receptors (FcγRs) in RA has been sorely neglected. The aim of this review was to introduce the different mouse models of RA and to describe the different drug development strategies that have been tested in these models to target FcγR function, with the focus being on drugs that have been made from the Fc of immunoglobulin G (IgG). <b><i>Summary:</i></b> Evidence suggests that FcγRs play a major role in immune complex-induced inflammation in autoimmune diseases, such as RA. However, there is limited knowledge on the importance of FcγRs in the human disease even though there has been extensive work in mouse models of RA. Numerous mouse models of RA are available, with each model depicting certain aspects of the disease. Induced models of RA have nonspecific immune activation with cartilage-directed autoimmunity, whereas spontaneous models of RA develop without immunization, which results in a more chronic form of arthritis. These models have been used to test FcγR-targeting monoclonal antibodies, intravenous immunoglobulin (IVIg), subcutaneously administered IVIg, and recombinant Fcs for their ability to interact with and modify FcγR function. Recombinant Fcs avidly bind FcγRs and exhibit enhanced therapeutic efficacy in mouse models of RA. <b><i>Key Message:</i></b> The therapeutic utility of targeting FcγRs with recombinant Fcs is great and should be explored in human clinical trials for autoimmune diseases, such as RA.

Vaccinal effect of HIV-1 antibody therapy

PURPOSE OF REVIEW

The review recalls recent findings regarding the induction of vaccinal effects by HIV-1 broadly neutralizing antibodies (bNAbs) and highlights potential therapeutic strategies to exploit such immunomodulatory properties.

RECENT FINDINGS

Studies in different animal models have shown that mAbs can generate long-lasting protective immunity. Induction of this vaccinal effect by HIV-1 bNAbs has also been more recently reported in animal models of HIV-1 infection. Notably, bNAbs treatment of macaques infected with the chimeric simian-human immunodeficiency virus (SHIV) improved both humoral and cellular adaptive immune responses that contributed to disease control. Importantly, this concept has been extended to HIV-1-infected patients as enhancement of humoral responses was recently reported in HIV-1 patients treated with bNAbs. Studies aiming at elucidating the mechanisms underlying these immunomodulatory properties of bNAbs have identified a role for immune complexes in shaping immune responses against HIV-1. They also highlight different Fc (fragment crystallizable) region effector functions that might be required for the enhancement of HIV-1 immune responses upon bNAbs treatment.

SUMMARY

HIV-1 bNAbs can elicit protective adaptive immune responses through mechanisms involving multiple cellular and molecular actors of the immune system. Harnessing these mechanisms will be crucial to achieve protective immunity against HIV-1 infection by bNAbs.

Phagocytosis: Our Current Understanding of a Universal Biological Process

Phagocytosis is a cellular process for ingesting and eliminating particles larger than 0.5 μm in diameter, including microorganisms, foreign substances, and apoptotic cells. Phagocytosis is found in many types of cells and it is, in consequence an essential process for tissue homeostasis. However, only specialized cells termed professional phagocytes accomplish phagocytosis with high efficiency. Macrophages, neutrophils, monocytes, dendritic cells, and osteoclasts are among these dedicated cells. These professional phagocytes express several phagocytic receptors that activate signaling pathways resulting in phagocytosis. The process of phagocytosis involves several phases: i) detection of the particle to be ingested, ii) activation of the internalization process, iii) formation of a specialized vacuole called phagosome, and iv) maturation of the phagosome to transform it into a phagolysosome. In this review, we present a general view of our current understanding on cells, phagocytic receptors and phases involved in phagocytosis.

Engineered human FcγRIIa fusion: A novel strategy to extend serum half-life of therapeutic proteins

The immunoglobulin G (IgG) molecule has a long circulating serum half-life (~3 weeks) through pH- dependent FcRn binding-mediated recycling. To hijack the intracellular trafficking and recycling mechanism of IgG as a way to extend serum persistence of non-antibody therapeutic proteins, we have evolved the ectodomain of a low-affinity human FcγRIIa for enhanced binding to the lower hinge and upper CH2 region of IgG, which is very far from the FcRn binding site (CH2-CH3 interface). High-throughput library screening enabled isolation of an FcγRIIa variant (2A45.1) with 32-fold increased binding affinity to human IgG1 Fc (equilibrium dissociation constant: 9.04 × 10^-7  M for wild type FcγRIIa and 2.82 × 10^-8  M for 2A45.1) and significantly improved affinity to mouse serum IgG compared to wild type human FcγRIIa. The in vivo pharmacokinetic profile of PD-L1 fused with engineered FcγRIIa (PD-L1-2A45.1) was compared with that of PD-L1 fused with wild type FcγRIIa (PD-L1-wild type FcγRIIa) and human PD-L1 in mice. PD-L1-2A45.1 showed 11.7- and 9.7-fold prolonged circulating half-life (t_1/2 ) compared to PD-L1 when administered intravenously and intraperitoneally, respectively. In addition, the AUC_inf of PD-L1-2A45.1 was two-fold higher compared to that of PD-L1-wild type FcγRIIa. These results demonstrate that engineered FcγRIIa fusion offers a novel and successful strategy for prolonging serum half-life of therapeutic proteins.

Different clinical characteristics of longitudinally extensive transverse myelitis with and without connective tissue disorders: a single-center retrospective study

BACKGROUND AND OBJECTIVE

Autoimmune longitudinal extensive transverse myelitis (LETM) is often combined with connective tissue disorders (CTD). The purpose of this study was to compare the clinical characteristics of autoimmune LETM with and without CTD.

METHODS

Ninety-two patients diagnosed with autoimmune LETM were enrolled from our clinical database and divided into two groups depending on whether they had a concomitant diagnosis of CTD. Differences in clinical, serological, and imaging characteristics between the two groups were evaluated and compared.

RESULTS

Fifty-nine LETM patients without CTD and 33 LETM patients with CTD were included. LETM patients with CTD had higher Kurtzke Expanded Disability Status Scale at nadir and more severe sensory dysfunction (p < 0.05) than those without CTD. It was also found that LETM patients with CTD, compared with those without CTD, had elevated levels of immune inflammation markers such as IgG, IgA, and globulins (p < 0.05). These abovementioned characteristics were more prominent in patients with aquaporin-4 antibodies (AQP4-ab) than in those without them. In addition, the most common type of CTD in LETM was Sjögren syndrome (SS), which was usually diagnosed at the time of LETM or later.

CONCLUSION

LETM patients with CTD, especially those with AQP4-ab, had greater sensory dysfunction and higher levels of inflammatory markers than did LETM patients without CTD. Multicenter cooperation and long-term follow-up are necessary to further study the inherent implications and prognosis of the disease.

Fc-Linked IgG N-Glycosylation in FcγR Knock-Out Mice

Immunoglobulin G (IgG) is the most abundant immunoglobulin isotype in the blood and is involved in the pathogenesis and progression of various diseases. Glycosylation of the IgG fragment crystallizable (Fc) region is shown to vary in different physiological and pathological states. Fc N-glycan composition can alter the effector functions of IgG by modulating its affinity for ligands, such as Fcγ receptors (FcγRs). However, it is not known whether IgG glycosylation is affected by the available repertoire of FcγRs, and if the Fc-linked N-glycome can compensate for modulation of the IgG-FcγR interaction. To explore this, we examined the subclass-specific Fc IgG glycoprofiles of healthy male and female FcγR knock-out mice on C57BL/6 and BALB/c backgrounds. We observed slight changes in IgG Fc N-glycan profiles in different knock-outs; however, it seems that the strain background and sex have a stronger effect on N-glycosylation of IgG Fc regions than the FcγR repertoire.

Prediction of neoadjuvant chemotherapeutic efficacy in patients with locally advanced gastric cancer by serum IgG glycomics profiling

Background

Neoadjuvant chemotherapy (NACT) could improve prognosis and survival quality of patients with local advanced gastric cancer (LAGC) by providing an opportunity of radical operation for them. However, no effective method could predict the efficacy of NACT before surgery to avoid the potential toxicity, time-consuming and economic burden of ineffective chemotherapy. Some research has been investigated about the correlation between serum IgG glycosylation and gastric cancer, but the question of whether IgG glycome can reflect the tumor response to NACT is still unanswered.

Method

Serum IgG glycome profiles were analyzed by Ultra Performance Liquid Chromatography in a cohort comprised of 49 LAGC patients of which 25 were categorized as belonging to the NACT response group and 24 patients were assigned to the non-response group. A logistic regression model was constructed to predict the response rate incorporating clinical features and differential N-glycans, while the precision of model was assessed by receiver operating characteristic (ROC) analysis.

Results

IgG N-glycome analysis in pretreatment serum of LAGC patients comprises 24 directly detected glycans and 17 summarized traits. Compared with IgG glycans of non-response group, agalactosylated N-glycans increased while monosialylated N-glycans and digalactosylated N-glycans decreased in the response group. We constructed a model combining patients' age, histology, chemotherapy regimen, GP4(H3N4F1), GP6(H3N5F1), and GP18(H5N4F1S1), and ROC analysis showed this model has an accurate prediction of NACT response (AUC = 0.840) with the sensitivity of 64.00% and the specificity of 100%.

Conclusion

We here firstly present the profiling of IgG N-glycans in pretreatment serum of LAGC. The alterations in IgG N-glycome may be personalized biomarkers to predict the response to NACT in LAGC and help to illustrate the relationship between immunity and effect of NACT.

Minimal B Cell Extrinsic IgG Glycan Modifications of Pro- and Anti-Inflammatory IgG Preparations in vivo

Select residues in the biantennary sugar moiety attached to the fragment crystallizable of immunoglobulin G (IgG) antibodies can modulate IgG effector functions. Thus, afucosylated IgG glycovariants have enhanced cytotoxic activity, whereas IgG glycovariants rich in terminal sialic acid residues can trigger anti-inflammatory effects. More recent evidence suggests that terminal α2,6 linked sialic acids can be attached to antibodies post IgG secretion. These findings raise concerns for the use of therapeutic antibodies as they may change their glycosylation status in the patient and hence affect their activity. To investigate to what extent B cell extrinsic sialylation processes modify therapeutic IgG preparations in vivo, we analyzed changes in human intravenous IgG (IVIg) sialylation upon injection in mice deficient in B cells or in mice lacking the sialyltransferase 1, which catalyzes the addition of α2,6 linked sialic acid residues. By performing a time course of IgG glycan analysis with HILIC-UPLC-FLR (plus MS) and xCGE-LIF our study suggests that therapeutic IgG glycosylation is stable upon injection in vivo. Only a very small fraction of IgG molecules acquired sialic acid structures predominantly in the Fab- but not the Fc-portion upon injection in vivo, suggesting that therapeutic antibody glycosylation will remain stable upon injection in vivo.

Rumen Fermentation Characteristics in Pre- and Post-Weaning Calves upon Feeding with Mulberry Leaf Flavonoids and Candida tropicalis Individually or in Combination as a Supplement

Although flavonoids or yeast have been used as feed additives to improve the production efficiency and health of adult cattle, little information is available on their effects on rumen fermentation in calves. The objective of this study was to investigate the effects of feed supplementation with mulberry leaf flavonoids and Candida tropicalis on performance, blood parameters, and rumen fermentation characteristics during pre-weaning and post-weaning periods. Forty-eight Holstein calves were used in a four-groups trial and were supplemented with (1) no yeast or flavonoids (CON), (2) active dry yeast (ADY; C. tropicalis, 5.0 × 10⁹ CFU/d), (3) flavonoids (FLA; 3 g/d), or (4) yeast and flavonoids (YF; C. tropicalis, 5.0 × 10⁹ CFU/d; flavonoids, 3 g/d). The feeding strategy was as follows: milk replacer was offered at 12% of body weight in two meals per calf each day at age 21 d, and a gradual weaning process was adopted at age 50 to 56 days. Data of daily feed intake, body weight, and serum and rumen fermentation parameters were obtained at 28, 42, 56, and 80 d ages, respectively. A significant time effect and interaction between treatment and time was found for average daily gain, feed efficiency, total volatile fatty acid concentration, and proportion of propionate in calves (p < 0.05). Average daily gain and feed efficiency increased during post-weaning and overall periods for calves in FLA and YF groups compared with CON and ADY groups (p < 0.05). A reduction of fecal scores with supplementation was found in FLA and YF groups (p < 0.05). Rumen fluid pH and ammonia nitrogen concentration remained constant across the groups, whereas total volatile fatty acid concentration and molar proportion of propionate significantly increased during the pre-weaning and overall periods in FLA and YF groups (p < 0.05). Calves in YF group had the highest serum concentrations of IgG and IgA during the overall period (p < 0.05). Additionally, serum β-hydroxybutyric acid concentration was higher in ADY and FLA groups during the post-weaning period (p < 0.05). Supplementation with C. tropicalis showed little effect on increasing growth performance and health compared with flavonoids alone. Meanwhile, the combination of C. tropicalis and flavonoids was not synergistic with respect to improving health and rumen fermentation compared with use of flavonoids alone in pre- and post-weaning calves (p > 0.05).

Striking a balance in an antibody network: A roadmap for HIV-1 vaccines

With almost 2 million new HIV-1 infections in 2018, a highly effective vaccine is imperative. Vaccine-elicited HIV-1 antibodies contribute to protection through multiple nonneutralizing activities, but the exact mechanisms remain unknown. In this issue of the JCI, Neidich and associates sought to determine how antibodies contributed to reducing the risk of HIV-1 acquisition in a phase IIb preventative vaccine efficacy trial, HVTN 505. Their studies revealed that antibody-dependent cellular phagocytosis (ADCP) and FcγRIIa binding were strongly associated with reduced HIV-1 risk; however, HIV-1 envelope-specific IgG3, IgA; and host FcγRIIa genotype also influenced risk. This study highlights the intricate interactions between antibodies and innate immune functions in humans.

Antibody Fc effector functions and IgG3 associate with decreased HIV-1 risk

HVTN 505 is a preventative vaccine efficacy trial testing DNA followed by recombinant adenovirus serotype 5 (rAd5) in circumcised, Ad5-seronegative men and transgendered persons who have sex with men in the United States. Identified immune correlates of lower HIV-1 risk and a virus sieve analysis revealed that, despite lacking overall efficacy, vaccine-elicited responses exerted pressure on infecting HIV-1 viruses. To interrogate the mechanism of the antibody correlate of HIV-1 risk, we examined antigen-specific antibody recruitment of Fcγ receptors (FcγRs), antibody-dependent cellular phagocytosis (ADCP), and the role of anti-envelope (anti-Env) IgG3. In a prespecified immune correlates analysis, antibody-dependent monocyte phagocytosis and antibody binding to FcγRIIa correlated with decreased HIV-1 risk. Follow-up analyses revealed that anti-Env IgG3 breadth correlated with reduced HIV-1 risk, anti-Env IgA negatively modified infection risk by Fc effector functions, and that vaccine recipients with a specific FcγRIIa single-nucleotide polymorphism locus had a stronger correlation with decreased HIV-1 risk when ADCP, Env-FcγRIIa, and IgG3 binding were high. Additionally, FcγRIIa engagement correlated with decreased viral load setpoint in vaccine recipients who acquired HIV-1. These data support a role for vaccine-elicited anti-HIV-1 Env IgG3, antibody engagement of FcRs, and phagocytosis as potential mechanisms for HIV-1 prevention.