The role of sialic acid-binding immunoglobulin-like-lectin-1 (siglec-1) in immunology and infectious disease

Comprehensive review on human Milk oligosaccharides: Biosynthesis, structure, intestinal health benefits, immune regulation, neuromodulation mechanisms, and applications

This review provides a comprehensive analysis of the biosynthetic pathways of various oligosaccharides in Escherichia coli, structural characteristics, and bioactive mechanisms of human milk oligosaccharides (HMOs), with a particular emphasis on their roles in gut health, immune modulation, and neurodevelopment. HMOs primarily function as prebiotics, facilitating the growth of beneficial bacteria such as Bifidobacterium to maintain microbial homeostasis, with a discussion on the synergistic role of carbohydrate-binding modules (CBMs). In immune modulation, HMOs interact with lectins on immune and epithelial cells, influencing immune responses via pathways such as Toll-like receptors (TLRs). Additionally, HMOs have been linked to enhanced cognitive, motor, and language development in infants, influencing genes such as GABRB2, SLC1A7, GLRA4, and CHRM3. The review also examines commercially available HMO-containing products and highlights future research directions and potential applications in nutrition and healthcare.

Knockdown of SIGLEC1 inhibits osteogenic differentiation to alleviate ankylosing spondylitis progression by suppressing the TGF-β1/SMAD signaling pathway

Ankylosing spondylitis (AS) is a chronic inflammatory joint disease, which can result in disability in severe cases and endanger physical health. Two microarray datasets related to AS were selected from NCBI for bioinformatics analysis. Differentially expressed genes (DEGs) were screened and protein-protein interaction network was constructed to obtain hub genes. hSMSCs were injected with TNF-α to construct AS cell models. The hSMSCs were transfected with SIGLEC1 siRNA to silence SIGLEC1 expression. CCK-8, western blot, qRT-PCR, and ELISA were performed to detect the effects of SIGLEC1 knockdown on cell proliferation, osteogenic differentiation (ALP, BMP2, Osterix, and Runx2), inflammation (IL-23 and IL-6), and TGF-β1/SMAD signaling pathway (SMAD3, SMAD7 and TGF-β1). A TGF-β1 activator was applied for feedback function assays. A total of 29 common DEGs were screened from GSE181364 and GSE221786, and the key gene SIGLEC1 was selected. Knockdown of SIGLEC1 promoted cell proliferation and inhibited ALP activity, the level of BMP2, Osterix and Runx2 in TNF-α-induced hSMSCs, as well as the decreased inflammatory factors IL-23 and IL-6. Furthermore, knockdown of SIGLEC1 inhibited the expression of TGF-β1/SMAD signaling pathway related proteins, while the treatment of TGF-β1 activator weakened the inhibiting effects of sh-SIGLEC1 on the osteogenic differentiation and inflammation in TNF-α-induced hSMSCs. In summary, knockdown of SIGLEC1 promoted cell proliferation and inhibited osteogenic differentiation and inflammation by inhibiting TGF-β1/SMAD signaling pathway, thereby suppressing the development of AS.

Polysialic acid-based nanoparticles for enhanced targeting and controlled dexamethasone release in pulmonary inflammation treatment

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are life-threatening conditions characterized by severe inflammation and respiratory failure. Despite the use of dexamethasone (Dex) in treatment, challenges such as poor solubility and systemic side effects persist, highlighting the need for novel therapeutic approaches. This study introduces an innovative nanoparticle delivery system based on chitosan (CS) and polysialic acid (PSA), engineered via electrostatic assembly, to improve the targeted delivery of Dex to inflamed lung tissues. To enhance drug encapsulation and stability, novel taurine-Vitamin E succinate amphiphilic molecules (TVES and TGVES) were synthesized. The unique ability of PSA to specifically target Siglec-1 receptors on M1 macrophages-key contributors to ALI/ARDS-related inflammation-positions this system as a promising strategy for targeted pulmonary therapies. In vitro targeting of M1 macrophages and in vivo reduction of inflammation demonstrate the potential to transform treatment by delivering therapeutic agents precisely to the site of need. This cutting-edge nanoparticle platform not only holds promise for improving ALI/ARDS outcomes but also paves the way for the application of functional additives like taurine in advanced medical therapies.

A comprehensive review of immune checkpoint inhibitors for cancer treatment

Immunology-based therapies are emerging as an effective cancer treatment, using the body's immune system to target tumors. Immune checkpoints, which regulate immune responses to prevent tissue damage and autoimmunity, are often exploited by cancer cells to avoid destruction. The discovery of checkpoint proteins like PD-1/PD-L1 and CTLA-4 was pivotal in developing cancer immunotherapy. Immune checkpoint inhibitors (ICIs) have shown great success, with FDA-approved drugs like PD-1 inhibitors (Nivolumab, Pembrolizumab, Cemiplimab), PD-L1 inhibitors (Atezolizumab, Durvalumab, Avelumab), and CTLA-4 inhibitors (Ipilimumab, Tremelimumab), alongside LAG-3 inhibitor Relatlimab. Research continues on new checkpoints like TIM-3, VISTA, B7-H3, BTLA, and TIGIT. Biomarkers like PDL-1 expression, tumor mutation burden, interferon-γ presence, microbiome composition, and extracellular matrix characteristics play a crucial role in predicting responses to immunotherapy with checkpoint inhibitors. Despite their effectiveness, not all patients experience the same level of benefit, and organ-specific immune-related adverse events (irAEs) such as rash or itching, colitis, diarrhea, hyperthyroidism, and hypothyroidism may occur. Given the rapid advancements in this field and the variability in patient outcomes, there is an urgent need for a comprehensive review that consolidates the latest findings on immune checkpoint inhibitors, covering their clinical status, biomarkers, resistance mechanisms, strategies to overcome resistance, and associated adverse effects. This review aims to fill this gap by providing an analysis of the current clinical status of ICIs, emerging biomarkers, mechanisms of resistance, strategies to enhance therapeutic efficacy, and assessment of adverse effects. This review is crucial to furthering our understanding of ICIs and optimizing their application in cancer therapy.

Siglecs-mediated immune regulation in neurological disorders

The surfaces of various immune cells are rich in glycan chains, including the sialic-acid-binding immunoglobulin-like lectins (Siglecs) family. As an emerging glyco-immune checkpoint, Siglecs have the ability to bind and interact with various glycoproteins, thereby eliciting a series of downstream reactions to modulate the immune response. The impact of Siglecs has been extensively studied in tumor immunotherapy. However, research in neurological disorders and neurological diseases is very limited, and therapeutic options involving Siglecs need further exploration. Siglecs play a crucial role in the development, homeostasis, and repair processes of the nervous system, especially in degenerative diseases. This review summarizes studies on the immunomodulatory role mediated by Siglecs expressed on different immune cells in various neurological disorders, elucidates how dysregulated sialic acid contributes to several psychiatric disorders, and discusses the progress and limitations of research on the treatment of neurological disorders.

Mechanistic and Therapeutic Implications of Protein and Lipid Sialylation in Human Diseases

Glycan structures of glycoproteins and glycolipids on the surface glycocalyx and luminal sugar layers of intracellular membrane compartments in human cells constitute a key interface between intracellular biological processes and external environments. Sialic acids, a class of alpha-keto acid sugars with a nine-carbon backbone, are frequently found as the terminal residues of these glycoconjugates, forming the critical components of these sugar layers. Changes in the status and content of cellular sialic acids are closely linked to many human diseases such as cancer, cardiovascular, neurological, inflammatory, infectious, and lysosomal storage diseases. The molecular machineries responsible for the biosynthesis of the sialylated glycans, along with their biological interacting partners, are important therapeutic strategies and targets for drug development. The purpose of this article is to comprehensively review the recent literature and provide new scientific insights into the mechanisms and therapeutic implications of sialylation in glycoproteins and glycolipids across various human diseases. Recent advances in the clinical developments of sialic acid-related therapies are also summarized and discussed.

Elusive Protein-Glycosphingolipid Interactions Revealed by Membrane Anchor-Assisted Native Mass Spectrometry

Interactions between glycan-binding proteins (GBPs) and glycosphingolipids (GSLs) present in cell membranes are implicated in a wide range of biological processes. However, studying GSL binding is hindered by the paucity of purified GSLs and the weak affinities typical of monovalent GBP-GSL interactions. Native mass spectrometry (nMS) performed using soluble model membranes is a promising approach for the discovery of GBP ligands, but the detection of weak interactions remains challenging. The present work introduces MEmbrane ANchor-assisted nMS (MEAN-nMS) for the detection of low-affinity GBP-GSL complexes. The assay utilizes a membrane anchor, produced by covalent cross-linking of the GBP and a lipid in the membrane, to localize the GBP on the surface and promote GSL binding. Ligands are identified by nMS detection of intact GBP-GSL complexes (MEAN-nMS) or using a catch-and-release (CaR) strategy, wherein GSLs are released from GBP-GSL complexes upon collisional activation and detected (MEAN-CaR-nMS). To establish reliability, a library of purified gangliosides incorporated into nanodiscs was screened against human immune lectins, and the results compared with affinities of the corresponding ganglioside oligosaccharides. Without a membrane anchor, nMS analysis yielded predominantly false negatives. In contrast, all ligands were identified by MEAN-(CaR)-nMS, with no false positives. To highlight the potential of MEAN-CaR-nMS for ligand discovery, a natural library of GSLs was incorporated into nanodiscs and screened against human and viral proteins to uncover elusive ligands. Finally, nMS-based detection of GSL ligands directly from cells is demonstrated. This breakthrough paves the way for shotgun glycomics screening using intact cells.

Preclinical development of humanized monoclonal antibodies against CD169 as a broad antiviral therapeutic strategy

New therapies to treat or prevent viral infections are essential, as recently observed during the COVID-19 pandemic. Here, we propose a therapeutic strategy based on monoclonal antibodies that block the specific interaction between the host receptor Siglec-1/CD169 and gangliosides embedded in the viral envelope. Antibodies are an excellent option for treating infectious diseases based on their high specificity, strong targeting affinity, and relatively low toxicity. Through a process of humanization, we optimized monoclonal antibodies to eliminate sequence liabilities and performed biophysical characterization. We demonstrated that they maintain their ability to block viral entry into myeloid cells. These molecular improvements during the discovery stage are key if we are to maximize efforts to develop new therapeutic strategies. Humanized monoclonal antibodies targeting CD169 provide new opportunities in the treatment of infections caused by ganglioside-containing enveloped viruses, which pose a constant threat to human health. In contrast with current neutralizing antibodies that bind antigens on the infectious particle, our antibodies can prevent several types of enveloped viruses interacting with host cells because they target the host CD169 protein, thus becoming a potential pan-antiviral therapy.

Durable protective efficiency provide by mRNA vaccines require robust immune memory to antigens and weak immune memory to lipid nanoparticles

The Pegylated lipids in lipid nanoparticle (LNPs) vaccines have been found to cause acute hypersensitivity reactions in recipients, and generate anti-LNPs immunity after repeated administration, thereby reducing vaccine effectiveness. To overcome these challenges, we developed a new type of LNPs vaccine (SAPC-LNPs) which was co-modified with sialic acid (SA) - lipid derivative and cleavable PEG - lipid derivative. This kind of mRNA vaccine can target dendritic cells (DCs) and rapidly escape from early endosomes (EE) and lysosomes with a total endosomal escape rate up to 98 %. Additionally, the PEG component in SAPC-LNPs was designed to detach from the LNPs under the catalysis of carboxylesterase in vivo, which reduced the probability of PEG being attached to LNPs entering antigen-presenting cells. Compared with commercially formulated vaccines (1.5PD-LNPs), mice treated with SAPC-LNPs generated a more robust immune memory to tumor antigens and a weaker immune memory response to LNPs, and showed lower side effects and long-lasting protective efficiency. We also discovered that the anti-tumor immune memory formed by SAPC-LNPs mRNA vaccine was directly involved in the immune cycle to rattack tumor. This immune memory continued to strengthen with multiple cycles, supporting that the immune memory should be incorporated into the theory of tumor immune cycle.

Elevated CD169 expressing monocyte/macrophage promotes systemic inflammation and disease progression in cirrhosis

Systemic inflammation is related to disease progression and prognosis in patients with advanced cirrhosis. However, the mechanisms underlying the initiation of inflammation are still not fully understood. The role of CD169+ monocyte/macrophage in cirrhotic systemic inflammation was undetected. Flow cytometry analysis was used to detect the percentage and phenotypes of CD169+ monocytes as well as their proinflammatory function in patient-derived cirrhotic tissue and blood. Transcriptome differences between CD169+ and CD169- monocytes were also compared. Additionally, a mouse model with specific depletion of CD169+ monocytes/macrophages was utilized to define their role in liver injury and fibrosis. We observed increased CD169 expression in monocytes from cirrhotic patients, which was correlated with inflammatory cytokine production and disease progression. CD169+ monocytes simultaneously highly expressed M1- and M2-like markers and presented immune-activated profiles. We also proved that CD169+ monocytes robustly prevented neutrophil apoptosis. Depletion of CD169+ monocytes/macrophages significantly inhibited inflammation and liver necrosis in acute liver injury, but the spontaneous fibrin resolution after repeated liver injury was impaired. Our results indicate that CD169 defines a subset of inflammation-associated monocyte that correlates with disease development in patients with cirrhosis. This provides a possible therapeutic target for alleviating inflammation and improving survival in cirrhosis.

Application of Cyclodextrin for Cancer Immunotherapy

Tumor immunotherapy, compared with other treatment strategies, has the notable advantage of a long-term therapeutic effect for preventing metastasis and the recurrence of tumors, thus holding great potential for the future of advanced tumor therapy. However, due to the poor water solubility of immune modulators and immune escape properties of tumor cells, the treatment efficiency of immunotherapy is usually significantly reduced. Cyclodextrin (CD) has been repeatedly highlighted to be probably one of the most investigated building units for cancer therapy due to its elegant integration of an internal hydrophobic hollow cavity and an external hydrophilic outer surface. The application of CD for immunotherapy provides new opportunities for overcoming the aforementioned obstacles. However, there are few published reviews, to our knowledge, summarizing the use of CD for cancer immunotherapy. For this purpose, this paper provides a comprehensive summary on the application of CD for immunotherapy with an emphasis on the role, function, and reported strategies of CD in mediating immunotherapy. This review summarizes the research progress made in using CD for tumor immunotherapy, which will facilitate the generation of various CD-based immunotherapeutic delivery systems with superior anticancer efficacy.

Modulation of Disease-Associated Pathways in Hidradenitis Suppurativa by the Janus Kinase 1 Inhibitor Povorcitinib: Transcriptomic and Proteomic Analyses of Two Phase 2 Studies

Janus kinase (JAK)/signal transducer and activator of transcription signaling (STAT) has been implicated in the pathophysiology of hidradenitis suppurativa (HS). This study evaluated treatment-related transcriptomic and proteomic changes in patients with moderate-to-severe HS treated with the investigational oral JAK1-selective inhibitor povorcitinib (INCB054707) in two phase 2 trials. Lesional skin punch biopsies (baseline and Week 8) were taken from active HS lesions of patients receiving povorcitinib (15 or 30 mg) once daily (QD) or a placebo. RNA-seq and gene set enrichment analyses were used to evaluate the effects of povorcitinib on differential gene expression among previously reported gene signatures from HS and wounded skin. The number of differentially expressed genes was the greatest in the 30 mg povorcitinib QD dose group, consistent with the published efficacy results. Notably, the genes impacted reflected JAK/STAT signaling transcripts downstream of TNF-α signaling, or those regulated by TGF-β. Proteomic analyses were conducted on blood samples obtained at baseline and Weeks 4 and 8 from patients receiving povorcitinib (15, 30, 60, or 90 mg) QD or placebo. Povorcitinib was associated with transcriptomic downregulation of multiple HS and inflammatory signaling markers as well as the reversal of gene expression previously associated with HS lesional and wounded skin. Povorcitinib also demonstrated dose-dependent modulation of several proteins implicated in HS pathophysiology, with changes observed by Week 4. The reversal of HS lesional gene signatures and rapid, dose-dependent protein regulation highlight the potential of JAK1 inhibition to modulate underlying disease pathology in HS.

Cytokine levels associated with favorable clinical outcome in the CAPSID randomized trial of convalescent plasma in patients with severe COVID-19

Objectives

To determine the profile of cytokines in patients with severe COVID-19 who were enrolled in a trial of COVID-19 convalescent plasma (CCP).

Methods

Patients were randomized to receive standard treatment and 3 CCP units or standard treatment alone (CAPSID trial, ClinicalTrials.gov NCT04433910). The primary outcome was a dichotomous composite outcome (survival and no longer severe COVID-19 on day 21). Time to clinical improvement was a key secondary endpoint. The concentrations of 27 cytokines were measured (baseline, day 7). We analyzed the change and the correlation between serum cytokine levels over time in different subgroups and the prediction of outcome in receiver operating characteristics (ROC) analyses and in multivariate models.

Results

The majority of cytokines showed significant changes from baseline to day 7. Some were strongly correlated amongst each other (at baseline the cluster IL-1ß, IL-2, IL-6, IL-8, G-CSF, MIP-1α, the cluster PDGF-BB, RANTES or the cluster IL-4, IL-17, Eotaxin, bFGF, TNF-α). The correlation matrix substantially changed from baseline to day 7. The heatmaps of the absolute values of the correlation matrix indicated an association of CCP treatment and clinical outcome with the cytokine pattern. Low levels of IP-10, IFN-γ, MCP-1 and IL-1ß on day 0 were predictive of treatment success in a ROC analysis. In multivariate models, low levels of IL-1ß, IFN-γ and MCP-1 on day 0 were significantly associated with both treatment success and shorter time to clinical improvement. Low levels of IP-10, IL-1RA, IL-6, MCP-1 and IFN-γ on day 7 and high levels of IL-9, PDGF and RANTES on day 7 were predictive of treatment success in ROC analyses. Low levels of IP-10, MCP-1 and high levels of RANTES, on day 7 were associated with both treatment success and shorter time to clinical improvement in multivariate models.

Conclusion

This analysis demonstrates a considerable dynamic of cytokines over time, which is influenced by both treatment and clinical course of COVID-19. Levels of IL-1ß and MCP-1 at baseline and MCP-1, IP-10 and RANTES on day 7 were associated with a favorable outcome across several endpoints. These cytokines should be included in future trials for further evaluation as predictive factors.