Dendritic cell migration in health and disease

Ena/VASP proteins at the crossroads of actin nucleation pathways in dendritic cell migration

As sentinels of our immune system dendritic cells (DCs) rely on efficient cell migration for patrolling peripheral tissues and delivering sampled antigens to secondary lymphoid organs for the activation of T-cells. Dynamic actin polymerization is key to their macropinocytic and migratory properties. Both major actin nucleation machineries, formins and the Arp2/3 complex, are critical for different aspects of DC functionality, by driving the generation of linear and branched actin filaments, respectively. However, the importance of a third group of actin nucleators, the Ena/VASP family, has not been addressed yet. Here, we show that the two family members Evl and VASP are expressed in murine DCs and that their loss negatively affects DC macropinocytosis, spreading, and migration. Our interactome analysis reveals Ena/VASP proteins to be ideally positioned for orchestrating the different actin nucleation pathways by binding to the formin mDia1 as well as to the WAVE regulatory complex, a stimulator of Arp2/3. In fact, Evl/VASP deficient murine DCs are more vulnerable to inhibition of Arp2/3 demonstrating that Ena/VASP proteins contribute to the robustness and efficiency of DC migration.

A Morbillivirus Infection Shifts DC Maturation Toward a Tolerogenic Phenotype to Suppress T Cell Activation

Viruses have evolved numerous strategies to impair immunity so that they can replicate more efficiently. Among those, the immunosuppressive effects of morbillivirus infection can be particularly problematic, as they allow secondary infections to take hold in the host, worsening disease prognosis. In the present work, we hypothesized that the highly contagious morbillivirus peste des petits ruminants virus (PPRV) could target monocytes and dendritic cells (DC) to contribute to the immunosuppressive effects produced by the infection. Monocytes isolated from healthy sheep, a natural host of the disease, were able be infected by PPRV and this impaired the differentiation and phagocytic ability of immature monocyte-derived DC (MoDC). We also assessed PPRV capacity to infect differentiated MoDC. Ovine MoDC could be productively infected by PPRV, and this drastically reduced MoDC capacity to activate allogeneic T cell responses. Transcriptomic analysis of infected MoDC indicated that several tolerogenic DC signature genes were upregulated upon PPRV infection. Furthermore, PPRV-infected MoDC could impair the proliferative response of autologous CD4⁺ and CD8⁺ T cell to the mitogen concanavalin A (ConA), which indicated that DC targeting by the virus could promote immunosuppression. These results shed new light on the mechanisms employed by morbillivirus to suppress the host immune responses. IMPORTANCE Morbilliviruses pose a threat to global health given their high infectivity. The morbillivirus peste des petits ruminants virus (PPRV) severely affects small-ruminant-productivity and leads to important economic losses in communities that rely on these animals for subsistence. PPRV produces in the infected host a period of severe immunosuppression that opportunistic pathogens exploit, which worsens the course of the infection. The mechanisms of PPRV immunosuppression are not fully understood. In the present work, we demonstrate that PPRV can infect professional antigen-presenting cells called dendritic cells (DC) and disrupt their capacity to elicit an immune response. PPRV infection promoted a DC activation profile that favored the induction of tolerance instead of the activation of an antiviral immune response. These results shed new light on the mechanisms employed by morbilliviruses to suppress the immune responses.

Dendritic Cells: The Long and Evolving Road towards Successful Targetability in Cancer

Dendritic cells (DCs) are a unique myeloid cell lineage that play a central role in the priming of the adaptive immune response. As such, they are an attractive target for immune oncology based therapeutic approaches. However, targeting these cells has proven challenging with many studies proving inconclusive or of no benefit in a clinical trial setting. In this review, we highlight the known and unknown about this rare but powerful immune cell. As technologies have expanded our understanding of the complexity of DC development, subsets and response features, we are now left to apply this knowledge to the design of new therapeutic strategies in cancer. We propose that utilization of these technologies through a multiomics approach will allow for an improved directed targeting of DCs in a clinical trial setting. In addition, the DC research community should consider a consensus on subset nomenclature to distinguish new subsets from functional or phenotypic changes in response to their environment.

Human Milk Oligosaccharide 2'-Fucosyllactose Modulates Local Viral Immune Defense by Supporting the Regulatory Functions of Intestinal Epithelial and Immune Cells

Human milk contains bioactive components that provide protection against viral infections in early life. In particular, intestinal epithelial cells (IEC) have key regulatory roles in the prevention of enteric viral infections. Here we established an in vitro model to study the modulation of host responses against enteric viruses mimicked by poly I:C (pIC). The effects of 2′-fucosyllactose (2′FL), abundantly present in human milk, were studied on IEC and/or innate immune cells, and the subsequent functional response of the adaptive immune cells. IEC were pre-incubated with 2′FL and stimulated with naked or Lyovec™-complexed pIC (LV-pIC). Additionally, monocyte-derived dendritic cells (moDC) alone or in co-culture with IEC were stimulated with LV-pIC. Then, conditioned-moDC were co-cultured with naïve CD4⁺ T helper (Th)-cells. IEC stimulation with naked or LV-pIC promoted pro-inflammatory IL-8, CCL20, GROα and CXCL10 cytokine secretion. However, only exposure to LV-pIC additionally induced IFNβ, IFNλ1 and CCL5 secretion. Pre-incubation with 2′FL further increased pIC induced CCL20 secretion and LV-pIC induced CXCL10 secretion. LV-pIC-exposed IEC/moDC and moDC cultures showed increased secretion of IL-8, GROα, IFNλ1 and CXCL10, and in the presence of 2′FL galectin-4 and -9 were increased. The LV-pIC-exposed moDC showed a more pronounced secretion of CCL20, CXCL10 and CCL5. The moDC from IEC/moDC cultures did not drive T-cell development in moDC/T-cell cultures, while moDC directly exposed to LV-pIC secreted Th1 driving IL-12p70 and promoted IFNγ secretion by Th-cells. Hereby, a novel intestinal model was established to study mucosal host-defense upon a viral trigger. IEC may support intestinal homeostasis, regulating local viral defense which may be modulated by 2′FL. These results provide insights regarding the protective capacity of human milk components in early life.

The modulatory role of dendritic cell-T cell cross-talk in breast cancer: Challenges and prospects

Antigen recognition and presentation are highlighted as the first steps in developing specialized antigen responses. Dendritic cells (DCs) are outstanding professional antigen-presenting cells (APCs) responsible for priming cellular immunity in pathological states, including cancer. However, the diminished or repressed function of DCs is thought to be a substantial mechanism through which tumors escape from the immune system. In this regard, DCs obtained from breast cancer (BC) patients represent a notably weakened potency to encourage specific T-cell responses. Additionally, impaired DC-T-cell cross-talk in BC facilitates the immune evade of cancer cells and is connected with tumor advancement, immune tolerance, and adverse prognosis for patients. In this review we aim to highlight the available knowledge on DC-T-cell interactions in BC aggressiveness and show its therapeutic potential in BC treatment.

IFITM3 restricts virus-induced inflammatory cytokine production by limiting Nogo-B mediated TLR responses

Interferon-induced transmembrane protein 3 (IFITM3) is a restriction factor that limits viral pathogenesis and exerts poorly understood immunoregulatory functions. Here, using human and mouse models, we demonstrate that IFITM3 promotes MyD88-dependent, TLR-mediated IL-6 production following exposure to cytomegalovirus (CMV). IFITM3 also restricts IL-6 production in response to influenza and SARS-CoV-2. In dendritic cells, IFITM3 binds to the reticulon 4 isoform Nogo-B and promotes its proteasomal degradation. We reveal that Nogo-B mediates TLR-dependent pro-inflammatory cytokine production and promotes viral pathogenesis in vivo, and in the case of TLR2 responses, this process involves alteration of TLR2 cellular localization. Nogo-B deletion abrogates inflammatory cytokine responses and associated disease in virus-infected IFITM3-deficient mice. Thus, we uncover Nogo-B as a driver of viral pathogenesis and highlight an immunoregulatory pathway in which IFITM3 fine-tunes the responsiveness of myeloid cells to viral stimulation.

Rickettsia-Host-Tick Interactions: Knowledge Advances and Gaps

Ticks are hematophagous ectoparasites capable of transmitting multiple human pathogens. Environmental changes have supported the expansion of ticks into new geographical areas that have become the epicenters of tick-borne diseases (TBDs). The spotted fever group (SFG) of Rickettsia frequently infects ticks and causes tick-transmitted rickettsioses in areas of endemicity where ixodid ticks support host transmission during blood feeding. Ticks also serve as a reservoir for SFG Rickettsia. Among the members of SFG Rickettsia, R. rickettsii causes Rocky Mountain spotted fever (RMSF), the most lethal TBD in the United States. Cases of RMSF have been reported for over a century in association with several species of ticks in the United States. However, the isolation of R. rickettsii from ticks has decreased, and recent serological and epidemiological studies suggest that novel species of SFG Rickettsia are responsible for the increased number of cases of RMSF-like rickettsioses in the United States. Recent analyses of rickettsial genomes and advances in genetic and molecular studies of Rickettsia provided insights into the biology of Rickettsia with the identification of conserved and unique putative virulence genes involved in the rickettsial life cycle. Thus, understanding Rickettsia-host-tick interactions mediating successful disease transmission and pathogenesis for SFG rickettsiae remains an active area of research. This review summarizes recent advances in understanding how SFG Rickettsia species coopt and manipulate ticks and mammalian hosts to cause rickettsioses, with a particular emphasis on newly described or emerging SFG Rickettsia species.

Intradermal Allergen Immunotherapy for Allergic Rhinitis: Current Evidence

Allergic rhinitis (AR) is an immunoglobulin E (IgE)-mediated inflammatory disease that is induced by allergen introduction to the nasal mucosa, which triggers an inflammatory response. The current treatments for AR include allergen avoidance and pharmacotherapy; however, allergen-specific immunotherapy (AIT) is the only treatment that can be employed to modify immunologic responses and to achieve a cure for allergic diseases. The current standard routes of AIT administration are the subcutaneous and sublingual routes. Alternatively, the dermis contains a high density of dermal dendritic cells that act as antigen-presenting cells, so intradermal administration may confer added advantages and increase the efficacy of AIT. Moreover, intradermal immunotherapy (IDIT) may facilitate a reduction in the allergen dosage and a shortening of the treatment duration. The aim of this review was to search and evaluate the current evidence specific to IDIT, including its modified formulations, such as allergoids and peptides. The results of this review reveal conflicting evidence that suggests that the overall benefit of IDIT remains unclear. As such, further clinical trials are needed to establish the clinical utility of IDIT, and to determine the optimal treatment-related protocols.

Tumour Derived Extracellular Vesicles: Challenging Target to Blunt Tumour Immune Evasion

Simple Summary

Tumour onset and development occur because of specific immune support. The immune system, which is originally able to perceive and eliminate incipient cancer cells, becomes suppressed and hijacked by cancer. For these purposes, tumour cells use extracellular vesicles (TEVs). Specific molecular composition allows TEVs to reprogram immune cells towards tumour tolerance. Circulating TEVs move from their site of origin to other organs, preparing “a fertile soil” for metastasis formation. This implies that TEV molecular content can provide a valuable tool for cancer biomarker discovery and potential targets to reshape the immune system into tumour recognition and eradication.

Abstract

Control of the immune response is crucial for tumour onset and progression. Tumour cells handle the immune reaction by means of secreted factors and extracellular vesicles (EV). Tumour-derived extracellular vesicles (TEV) play key roles in immune reprogramming by delivering their cargo to different immune cells. Tumour-surrounding tissues also contribute to tumour immune editing and evasion, tumour progression, and drug resistance via locally released TEV. Moreover, the increase in circulating TEV has suggested their underpinning role in tumour dissemination. This review brings together data referring to TEV-driven immune regulation and antitumour immune suppression. Attention was also dedicated to TEV-mediated drug resistance.

Antigen transfer and its effect on vaccine-induced immune amplification and tolerance

Antigen transfer refers to the process of intercellular information exchange, where antigenic components including nucleic acids, antigen proteins/peptides and peptide-major histocompatibility complexes (p-MHCs) are transmitted from donor cells to recipient cells at the thymus, secondary lymphoid organs (SLOs), intestine, allergic sites, allografts, pathological lesions and vaccine injection sites via trogocytosis, gap junctions, tunnel nanotubes (TNTs), or extracellular vesicles (EVs). In the context of vaccine inoculation, antigen transfer is manipulated by the vaccine type and administration route, which consequently influences, even alters the immunological outcome, i.e., immune amplification and tolerance. Mainly focused on dendritic cells (DCs)-based antigen receptors, this review systematically introduces the biological process, molecular basis and clinical manifestation of antigen transfer.

Actions of Dendritic Cells in the Kidney during Hypertension

The immune response plays a critical role in the pathogenesis of hypertension, and immune cell populations can promote blood pressure elevation via actions in the kidney. Among these cell lineages, dendritic cells (DCs), the most potent antigen-presenting cells, play a central role in regulating immune response during hypertension and kidney disease. DCs have different subtypes, and renal DCs are comprised of the CD103⁺ CD11b^- and CD103^- CD11b⁺ subsets. DCs become mature and express costimulatory molecules on their surface once they encounter antigen. Isolevuglandin-modified proteins function as antigens to activate DCs and trigger them to stimulate T cells. Activated T cells accumulate in the hypertensive kidney, release effector cytokines, promote renal oxidative stress, and promote renal salt and water retention. Individual subsets of activated T cells can secrete tumor necrosis factor-alpha, interleukin-17A, and interferon-gamma, each of which has augmented the elevation of blood pressure in hypertensive models by enhancing renal sodium transport. Fms-like tyrosine kinase 3 ligand-dependent classical DCs are required to sustain the full hypertensive response, but C-X₃ -C chemokine receptor 1 positive DCs do not regulate blood pressure. Excess sodium enters the DC through transporters to activate DCs, whereas the ubiquitin editor A20 in dendritic cells constrains blood pressure elevation by limiting T cell activation. By contrast, activation of the salt sensing kinase, serum/glucocorticoid kinase 1 in DCs exacerbates salt-sensitive hypertension. This article discusses recent studies illustrating mechanisms through which DC-T cell interactions modulate levels of pro-hypertensive mediators to regulate blood pressure via actions in the kidney. © 2022 American Physiological Society. Compr Physiol 12:1-15, 2022.

A Stable Chemokine Gradient Controls Directional Persistence of Migrating Dendritic Cells

Navigation of dendritic cells (DCs) from the site of infection to lymphoid organs is guided by concentration gradients of CCR7 ligands. How cells interpret chemokine gradients and how they couple directional sensing to polarization and persistent chemotaxis has remained largely elusive. Previous experimental systems were limited in the ability to control fast de novo formation of the final gradient slope, long-lasting stability of the gradient and to expose cells to dynamic stimulation. Here, we used a combination of microfluidics and quantitative in vitro live cell imaging to elucidate the chemotactic sensing strategy of DCs. The microfluidic approach allows us to generate soluble gradients with high spatio-temporal precision and to analyze actin dynamics, cell polarization, and persistent directional migration in both static and dynamic environments. We demonstrate that directional persistence of DC migration requires steady-state characteristics of the soluble gradient instead of temporally rising CCL19 concentration, implying that spatial sensing mechanisms control chemotaxis of DCs. Kymograph analysis of actin dynamics revealed that the presence of the CCL19 gradient is essential to stabilize leading edge protrusions in DCs and to determine directionality, since both cytoskeletal polarization and persistent chemotaxis are abrogated in the range of seconds when steady-state gradients are perturbed. In contrast to Dictyostelium amoeba, DCs are unable to decode oscillatory stimulation of soluble chemokine traveling waves into a directional response toward the wave source. These findings are consistent with the notion that DCs do not employ adaptive temporal sensing strategies that discriminate temporally increasing and decreasing chemoattractant concentrations in our setting. Taken together, in our experimental system DCs do not depend on increasing absolute chemokine concentration over time to induce persistent migration and do not integrate oscillatory stimulation. The observed capability of DCs to migrate with high directional persistence in stable gradients but not when subjected to periodic temporal cues, identifies spatial sensing as a key requirement for persistent chemotaxis of DCs.

“Iron triangle” of regulating the uterine microecology: Endometrial microbiota, immunity and endometrium

The uterus is the core place for breeding new life. The balance and imbalance of uterine microecology can directly affect or even dominate the female reproductive health. Emerging data demonstrate that endometrial microbiota, endometrium and immunity play an irreplaceable role in regulating uterine microecology, forming a dynamic iron triangle relationship. Up to nowadays, it remains unclear how the three factors affect and interact with each other, which is also a frontier topic in the emerging field of reproductive tract microecology. From this new perspective, we aim to clarify the relationship and mechanism of the interaction of these three factors, especially their pairwise interactions. Finally, the limitations and future perspectives of the current studies are summarized. In general, these three factors have a dynamic relationship of mutual dependence, promotion and restriction under the physiological or pathological conditions of uterus, among which the regulatory mechanism of microbiota and immunity plays a role of bridge. These findings can provide new insights and measures for the regulation of uterine microecology, the prevention and treatment of endometrial diseases, and the further multi-disciplinary integration between microbiology, immunology and reproductive medicine.

Molecular and cellular mechanisms underlying postoperative paralytic ileus by various immune cell types

Postoperative ileus (POI) is a well-known complication following gut manipulation or surgical trauma, leading to an impaired gut motility and prolonged postoperative recovery time. Few current therapeutic strategies can prevent POI, and this disorder remains to be a major clinical challenge for patients undergoing surgery. Comprehensive understanding of cellular and molecular mechanisms related to the pathogenesis of POI stimulates the discovery of more promising targets for treatment. POI is closely associated with a series of inflammatory events within the bowel wall, and as key components of inflammatory mechanisms, different types of immune cells, including macrophages, dendritic cells, and T lymphocytes, play significant roles during the development of POI. A variety of immune cells are recruited into the manipulation sites after surgery, contributing to early inflammatory events or impaired gut motility. Our review intends to summarize the specific relationship between different immune cells and POI, mainly focusing on the relevant mechanisms underlying this disorder.

Curcumin and Curcuma longa Extract in the Treatment of 10 Types of Autoimmune Diseases: A Systematic Review and Meta-Analysis of 31 Randomized Controlled Trials

Objective

To evaluate the randomized controlled trials (RCTs) of Curcumin and Curcuma longa Extract in the treatment of autoimmune diseases.

Methods

Databases such as Embase, Web of Science, PubMed and The Cochrane Library were searched from the database establishment to February 2022 to collect RCTs of Curcumin and Curcuma longa Extract in the treatment of autoimmune diseases. Then the literature was screened and the data were extracted. Meta-analysis was performed using RevMan 5.3 software.

Results

A total of 34 records were included, involving 31 RCTs and 10 types of autoimmune disease. Among them, ankylosing spondylitis (AS) involves one RCT, Behcet ‘s disease (BD) involves one RCT, Crohn ‘s disease involves two RCTs, multiple sclerosis (MS) involves two RCTs, oral lichen planus involves six RCTs, psoriasis involves two RCTs, rheumatoid arthritis (RA) involves five RCTs, systemic lupus erythematosus (SLE) involves two RCTs, arteritis involves one RCT, ulcerative colitis (UC) involves nine RCTs. Among them, most of the RCTs of ulcerative colitis (UC), oral lichen planus, RA showed that curcumin and curcumin extracts improved clinical or laboratory results. Crohn ‘ s disease, MS, SLE, psoriasis included two RCTs; they all showed improvements (at least one RCT reported improvements in clinical outcomes). AS, BD and arteritis included only one RCT, and the clinical results showed improvement. However, due to the small number of RCTs and the small number of patients involved in each disease, there is still a need for more high-quality RCTs.

Conclusion

Curcumin and Curcuma longa Extract had good clinical efficacy in the treatment of Psoriasis, UC and RA, so Curcumin and Curcuma longa Extract could be used in the treatment of the above diseases in the future. The results of Meta-analysis showed that Curcumin and Curcuma longa Extract did not show efficacy in the treatment of oral lichen planus, while Takayasu arteritis, SLE, MS, AS, BD and CD did not report sufficient clinical data for meta-analysis. Therefore, large-sample, multi-center clinical trials are still needed for revision or validation.

Elastic Nanovaccine Enhances Dendritic Cell-Mediated Tumor Immunotherapy

Nanovaccine-based immunotherapy (NBI) has the ability to initiate dendritic cell (DC)-mediated tumor-specific immune responses and maintain long-term antitumor immune memory. To date, the mechanism by which the mechanical properties of nanoparticles alter the functions of DCs in NBI remains largely unclear. Here, a soft mesoporous organosilica-based nanovaccine (SMONV) is prepared and the elasticity-dependent effect of the nanovaccine on the underlying DC-mediated immune responses is studied. It is found that the elasticity results in greater internalization of SMONV by DCs, followed by the induction of substantial cytosolic delivery of antigens via endosomal escape, leading to effective DC maturation and antigen cross-presentation. Impressively, elasticity enables SMONV to enhance lymphatic drainage of antigens in vivo, thus stimulating robust humoral and cellular immunity. The results from therapeutic tumor vaccination further reveal that subcutaneously administered SMONV effectively suppresses tumor growth in tumor-bearing mice by evoking antigen-specific CD8⁺ T-cell immune responses, mitigating regulatory T-cell-mediated immunosuppression, and increasing central memory and effector memory T-cell populations. Furthermore, combinatorial immunization with SMONV and anti-PD-L1 blocking antibodies results in an amplified therapeutic effect on tumor-bearing mice. These findings reveal the elastic effect of the nanovaccine on DC-mediated immune responses, and the prepared SMONV represents a facile and powerful strategy for antitumor immunotherapy.

Human surfactant protein D facilitates SARS-CoV-2 pseudotype binding and entry in DC-SIGN expressing cells, and downregulates spike protein induced inflammation

Lung surfactant protein D (SP-D) and Dendritic cell-specific intercellular adhesion molecules-3 grabbing non-integrin (DC-SIGN) are pathogen recognising C-type lectin receptors. SP-D has a crucial immune function in detecting and clearing pulmonary pathogens; DC-SIGN is involved in facilitating dendritic cell interaction with naïve T cells to mount an anti-viral immune response. SP-D and DC-SIGN have been shown to interact with various viruses, including SARS-CoV-2, an enveloped RNA virus that causes COVID-19. A recombinant fragment of human SP-D (rfhSP-D) comprising of α-helical neck region, carbohydrate recognition domain, and eight N-terminal Gly-X-Y repeats has been shown to bind SARS-CoV-2 Spike protein and inhibit SARS-CoV-2 replication by preventing viral entry in Vero cells and HEK293T cells expressing ACE2. DC-SIGN has also been shown to act as a cell surface receptor for SARS-CoV-2 independent of ACE2. Since rfhSP-D is known to interact with SARS-CoV-2 Spike protein and DC-SIGN, this study was aimed at investigating the potential of rfhSP-D in modulating SARS-CoV-2 infection. Coincubation of rfhSP-D with Spike protein improved the Spike Protein: DC-SIGN interaction. Molecular dynamic studies revealed that rfhSP-D stabilised the interaction between DC-SIGN and Spike protein. Cell binding analysis with DC-SIGN expressing HEK 293T and THP- 1 cells and rfhSP-D treated SARS-CoV-2 Spike pseudotypes confirmed the increased binding. Furthermore, infection assays using the pseudotypes revealed their increased uptake by DC-SIGN expressing cells. The immunomodulatory effect of rfhSP-D on the DC-SIGN: Spike protein interaction on DC-SIGN expressing epithelial and macrophage-like cell lines was also assessed by measuring the mRNA expression of cytokines and chemokines. RT-qPCR analysis showed that rfhSP-D treatment downregulated the mRNA expression levels of pro-inflammatory cytokines and chemokines such as TNF-α, IFN-α, IL-1β, IL- 6, IL-8, and RANTES (as well as NF-κB) in DC-SIGN expressing cells challenged by Spike protein. Furthermore, rfhSP-D treatment was found to downregulate the mRNA levels of MHC class II in DC expressing THP-1 when compared to the untreated controls. We conclude that rfhSP-D helps stabilise the interaction between SARS- CoV-2 Spike protein and DC-SIGN and increases viral uptake by macrophages via DC-SIGN, suggesting an additional role for rfhSP-D in SARS-CoV-2 infection.

The reservoir of latent HIV

The persistence of latent reservoir of the human immunodeficiency virus (HIV) is currently the major challenge in curing HIV infection. After HIV infects the human body, the latent HIV is unable to be recognized by the body’s immune system. Currently, the widely adopted antiretroviral therapy (ART) is also unble to eliminate it, thus hindering the progress of HIV treatment. This review discusses the existence of latent HIV vault for HIV treatment, its formation and factors affecting its formation, cell, and tissue localization, methods for detection and removing latent reservoir, to provide a comprehensive understanding of latent HIV vault, in order to assist in the future research and play a potential role in achieving HIV treatment.

A therapeutic DC vaccine with maintained immunological activity exhibits robust anti-tumor efficacy

Dendritic cells (DCs) vaccines are a major focus of future anti-tumor immunotherapy for their pivotal role in eliciting reactive tumor-specific T-cell responses. Tumor cell-mediated DCs (TC-DC) activation and tumor antigen-mediated DCs (TA-DC) activation are two conventional modes of DC vaccine construction in clinical studies. The former physiologically mimicks the tumor identification and rejection, significantly contributing to DC-based immune recognition and migration towards the complexed tumor microenvironment (TME). However, as immunosuppressive molecules may exist in TME, these TC-DC are generally characterized with aberrant lipid accumulation and inositol-requiring kinase 1α (IRE1α)-X-box binding protein 1 (XBP1) hyperactivation, which is provoked by overwhelming oxidative stress and endoplasmic reticulum (ER) stress, resulting in TC-DC malfunction. Oppositely, without contacting immunosuppressive TME, TA-DC vaccines perform better in T-cell priming and lymph nodes (LNs) homing, but are relatively weak in TME infiltration and identification. Herein, we prepared a KIRA6-loaded α-Tocopherol nanoemulsion (KT-NE), which simultaneously ameliorated oxidative stress and ER stress in the dysfunctional lipid-laden TC-DC. The TC-DC treated by KT-NE could maintain immunological activity, simultaneously, exhibited satisfactory chemotaxis towards LNs and tumor sites in vivo, and effectively suppressed malignant progression by unleashing activated tumor-reactive T cells. This study generated a new DC-vaccine that owned puissant aptitude to identify complicated TME as well as robust immunological activity to boost T-cell initiation, which may provide some insights into the design and application of DC-vaccines for clinical application.

Low Surface Accessible Area NanoCoral TiO2 for the Reduction of Foreign Body Reaction During Implantation

The entry of implants triggers the secretion of damage associated molecular patterns (DAMPs) that recruit dendritic cells (DCs) and results in subsequent foreign body reaction (FBR). Though several studies have illustrated that the surface accessible area (SAA) of implants plays a key role in the process of DAMPs release and absorption, the effect of SAA on the immune reaction still remains unknown. Here, a series of TiO2 plates with different SAA is fabricated to investigate the relationship between SAA and FBR. Compared with larger SAA surface, the aggregation of DC is significantly inhibited by lower SAA surface. Total internal reflection microscopy (TIRFM) and molecular dynamic (MD) simulation show that although high mobility group box 1 (HMGB1) is adsorbed more on plates with lower SAA, the exposure ratio of cysteine (CYS) residue in HMGB1 is significantly decreased in lower SAA group. The lower exposure of CYS reduces the activation of Toll-like receptors 4 (TLR4), which down-regulates the expression of myeloid differentiation factor (Myd88)-TNF receptor associated factor 6 (TRAF6) to inhibit nuclear factor kappa B (NF-κB) signaling. Generally, this study reveals the mechanism of how SAA, a nanoscale property, affects FBR from perspective of DAMPs, and provides a new direction for designing better biocompatible implants.

High-Dimensional Immune Profiling by Mass Cytometry Revealed the Circulating Immune Cell Landscape in Patients With Intracranial Aneurysm

Background

Increasing evidence supports a critical role of chronic inflammation in intracranial aneurysm (IA). Understanding how the immunological alterations in IA provides opportunities for targeted treatment. However, there is a lack of comprehensive and detailed characterization of the changes in circulating immune cells in IA.

Objective

To perform a comprehensive and detailed characterization of the changes in circulating immune cells in patients with IA.

Methods

Peripheral blood mononuclear cell samples from IA patients (n = 26) and age-and sex-matched healthy controls (HCs, n = 20) were analyzed using high dimensional mass cytometry, and the frequency and phenotype of immune cell subtypes were assessed.

Results

We identified 28 cell clusters and found that the immune signature of IA consists of cluster changes. IA patients exhibited dysfunction of immunity, with dysregulation of CD4⁺ T-cell clusters, increased B cells and monocytes, and decreased CD8⁺ T cells, DNT cells, and DPT cells. Moreover, compared with findings in HC, IA was associated with enhanced lymphocyte and monocyte immune activation, with a higher expression of HLA-DR, CXCR3, and CX3CR1. In addition, the expression of TLR4, p-STAT3, and the exhaustion marker PD1 was increased in T cells, B cells, and NK cells in IA patients.

Conclusions

Our data provide an overview of the circulating immune cell landscape of IA patients, and reveal that the dysfunction of circulating immunity may play a potential role in the development of IA.

The role of dendritic cells in the immune niche of the peritoneum

Dendritic cells (DCs) are professional antigen presenting cells that play an important role in the induction of T cell responses. Different subsets (cDC1s, cDC2s, pDCs, and moDCs) were described based on the expression of different surface markers and functions. In the context of peritoneum, DCs are also a key population cell orchestrating immune responses against pathogens, malignant cells and tissue-damage. Furthermore, they play an important role in the promotion of an anti-inflammatory microenvironment, which is necessary to maintain tolerance and adipocyte homeostasis. The aim of this review is to summarize the current knowledge of the functional and phenotypic features of peritoneal DCs and shed some light on the importance of these cells within this unique cavity and its associated components: the omentum, the mesentery and gut-associated lymphoid tissue (GALT).

Dendritic cells can prime anti-tumor CD8+ T cell responses through major histocompatibility complex cross-dressing

Antigen cross-presentation, wherein dendritic cells (DCs) present exogenous antigen on major histocompatibility class I (MHC-I) molecules, is considered the primary mechanism by which DCs initiate tumor-specific CD8+ T cell responses. Here, we demonstrate that MHC-I cross-dressing, an antigen presentation pathway in which DCs acquire and display intact tumor-derived peptide:MHC-I molecules, is also important in orchestrating anti-tumor immunity. Cancer cell MHC-I expression was required for optimal CD8+ T cell activation in two subcutaneous tumor models. In vivo acquisition of tumor-derived peptide:MHC-I molecules by DCs was sufficient to induce antigen-specific CD8+ T cell priming. Transfer of tumor-derived human leukocyte antigen (HLA) molecules to myeloid cells was detected in vitro and in human tumor xenografts. In conclusion, MHC-I cross-dressing is crucial for anti-tumor CD8+ T cell priming by DCs. In addition to quantitatively enhancing tumor antigen presentation, MHC cross-dressing might also enable DCs to more faithfully and efficiently mirror the cancer cell peptidome.

Immune cell metabolism and metabolic reprogramming

Energy metabolism maintains the activation of intracellular and intercellular signal transduction, and plays a crucial role in immune response. Under environmental stimulation, immune cells change from resting to activation and trigger metabolic reprogramming. The immune system cells exhibit different metabolic characteristics when performing functions. The study of immune metabolism provides new insights into the function of immune cells, including how they differentiate, migrate and exert immune responses. Studies of immune cell energy metabolism are beginning to shed light on the metabolic mechanism of disease progression and reveal new ways to target inflammatory diseases such as autoimmune diseases, chronic viral infections, and cancer. Here, we discussed the relationship between immune cells and metabolism, and proposed the possibility of targeted metabolic process for disease treatment.

Granular Matrigel: restructuring a trusted extracellular matrix material for improved permeability

Matrigel is a polymeric extracellular matrix material produced by mouse cancer cells. Over the past four decades, Matrigel has been shown to support a wide variety of two- and three-dimensional cell and tissue culture applications including organoids. Despite widespread use, transport of molecules, cells, and colloidal particles through Matrigel can be limited. These limitations restrict cell growth, viability, and function and limit Matrigel applications. A strategy to improve transport through a hydrogel without modifying the chemistry or composition of the gel is to physically restructure the material into microscopic microgels and then pack them together to form a porous material. These 'granular' hydrogels have been created using a variety of synthetic hydrogels, but granular hydrogels composed of Matrigel have not yet been reported. Here we present a drop-based microfluidics approach for structuring Matrigel into a three-dimensional, mesoporous material composed of packed Matrigel microgels, which we call granular Matrigel. We show that restructuring Matrigel in this manner enhances the transport of colloidal particles and human dendritic cells (DCs) through the gel while providing sufficient mechanical support for culture of human gastric organoids (HGOs) and co-culture of human DCs with HGOs.

In Situ Micro-Nano Conversion Augmented Tumor-Localized Immunochemotherapy

The immune checkpoint blockade (ICB) therapy based on monoclonal antibodies still suffers from a lower immune response rate and severe immune-related side effects, which greatly compromise its therapeutic benefits. Herein, ultrasound (US) microbubbles (MBs) that locally delivered the camptothecin-floxuridine (CF) drug combination and anti-PD-L1 blocking antibody (αPD-L1) to tumors were developed to improve ICB therapy. The resulting αPCF MBs exhibited good stability, allowing their use as US imaging contrast agents to trace the drug delivery in vivo. Furthermore, the combination of αPCF MBs treatment and disrupted US irradiation triggered tumor in situ conversion of αPCF MBs to αPCF NPs while promoting higher tumor cell uptake and deeper tumor penetration as confirmed by the US/fluorescence bimodal imaging. Camptothecin (CPT) and floxuridine (FUDR) were further released at a fixed 1:1 molar ratio within the tumor microenvironment (TME) to synergistically elicit an immunogenic tumor phenotype and sensitize tumors to αPD-L1-mediated ICB therapy, while the local simultaneous delivery of immunotherapeutic αPD-L1 further reversed the immunosuppressive tumor microenvironment and promoted the infiltration of cytotoxic T lymphocytes (CTLs), thus achieving a synergistic therapeutic effect of chemotherapy and immunotherapy in the CT26 tumor-bearing mice. Thus, αPCF MBs + US mediated local co-delivering of the drug combination and αPD-L1 well augmented the ICB therapy while effectively minimizing the off-target side effects, providing a safe and universal therapeutic strategy for tumor immunotherapy.

Cyclooxygenase-Derived Prostaglandin E2 Drives IL-1-Independent Mycobacterium bovis Bacille Calmette-Guérin-Triggered Skin Dendritic Cell Migration to Draining Lymph Node

Inoculation of Mycobacterium bovis Bacille Calmette-Guérin (BCG) in the skin mobilizes local dendritic cells (DC) to the draining lymph node (dLN) in a process that remains incompletely understood. In this study, a mouse model of BCG skin infection was used to investigate mechanisms of skin DC migration to dLNs. We found enhanced transcription of cyclooxygenase (COX)-2 and production of COX-derived PGE₂ early after BCG infection in skin. Animals treated with antagonists for COX or the PGE₂ receptors EP2 and EP4 displayed a marked reduction in the entry of skin DCs and BCG to dLNs, uncovering an important contribution of COX-derived PGE₂ in this migration process. In addition, live BCG bacilli were needed to invoke DC migration through this COX-PGE₂ pathway. Having previously shown that IL-1R partially regulates BCG-induced relocation of skin DCs to dLNs, we investigated whether PGE₂ release was under control of IL-1. Interestingly, IL-1R ligands IL-1α/β were not required for early transcription of COX-2 or production of PGE₂ in BCG-infected skin, suggesting that the DC migration-promoting role of PGE₂ is independent of IL-1α/β in our model. In DC adoptive transfer experiments, EP2/EP4, but not IL-1R, was needed on the moving DCs for full-fledged migration, supporting different modes of action for PGE₂ and IL-1α/β. In summary, our data highlight an important role for PGE₂ in guiding DCs to dLNs in an IL-1–independent manner.

BCG-triggered PGE₂ release mobilizes skin DCs to the draining lymph node.

Migrating DCs use EP2 and EP4 to relocate to the draining lymph node.

Live BCG bacilli are needed for PGE₂-mediated DC migration.

Reprograming the immune niche for skin tissue regeneration - From cellular mechanisms to biomaterials applications

Despite the rapid development of therapeutic approaches for skin repair, chronic wounds such as diabetic foot ulcers remain an unaddressed problem that affects millions of people worldwide. Increasing evidence has revealed the crucial and diverse roles of the immune cells in the development and repair of the skin tissue, prompting new research to focus on further understanding and modulating the local immune niche for comprehensive, 'perfect' regeneration. In this review, we first introduce how different immunocytes and certain stromal cells involved in innate and adaptive immunity coordinate to maintain the immune niche and tissue homeostasis, with emphasis on their specific roles in normal and pathological wound healing. We then discuss novel engineering approaches - particularly biomaterials systems and cellular therapies - to target different players of the immune niche, with three major aims to i) overcome 'under-healing', ii) avoid 'over-healing', and iii) promote functional restoration, including appendage development. Finally, we highlight how these strategies strive to manage chronic wounds and achieve full structural and functional skin recovery by creating desirable 'soil' through modulating the immune microenvironment.

Dendritic cell vaccine as a potential strategy to end the COVID-19 pandemic. Why should it be Ex Vivo?

INTRODUCTION

Developing a safe and efficacious vaccine that can induce broad and long-term immunity for SARS-CoV-2 infection is the most critical research to date. As the most potent APCs, dendritic cells (DCs) can induce a robust T cell immunity. In addition, DCs also play an essential role in COVID-19 pathogenesis, making them a potential vaccination target. However, the DCs-based vaccine with ex vivo loading has not yet been explored for COVID-19.

AREAS COVERED

This review aims to provide the rationale for developing a DCs-based vaccine with ex vivo loading of SARS-CoV-2 antigen. Here, we discuss the role of DCs in immunity and the effect of SARS-CoV-2 infection on DCs. Then, we propose the mechanism of the DCs-based vaccine in inducing immunity and highlight the benefits of ex vivo loading of antigen.

EXPERT OPINION

We make the case that an ex vivo loaded DC-based vaccination is appropriate for COVID-19 prevention.

Gpr174 Knockout Alleviates DSS-Induced Colitis via Regulating the Immune Function of Dendritic Cells

Background

Dysfunction of the immune system would disturb the intestinal homeostasis and lead to inflammatory bowel disease (IBD). Dendritic cells (DCs) help maintain intestinal homeostasis and immediately respond to pathogens or injuries once the mucosa barriers are destroyed during IBD. G protein-coupled receptors(GPR)174 is an essential regulator of immunity that is widely expressed in most immune cells, including DCs. However, the role of GPR174 in regulating the immune function of DC in colitis has not been investigated.

Methods

Dextran sodium sulfate (DSS) was administered to establish the mice colitis model. Data of weight, length of colon, disease activity index (DAI), and macroscopic scores were collected. The flow cytometry was used to detect the infiltrations of T cells and DCs, the mean fluorescence intensity (MFI) of CD80, CD86, CD40, and major histocompatibility complex-II (MHC-II). And T cells proliferataion was measured by carboxyfluorescein diacetate succinimidyl ester (CFSE). The expression of cytokines (tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-10 (IL-10), interferon-γ (IFN-γ), interleukin -4 (IL-4)) and GPR174 mRNA were measured by Elisa, quantitative polymerase chain reaction (qPCR), and immunofluorescence. RNA of bone-marrow-derived dendritic cells (BMDCs) was extracted for sequencing. Adoptive transfer of BMDCs was administrated intravenously.

Results

Gpr174^-/- mice exposed to 3% DSS showed significant alleviation characterized by reduced loss of weight, more minor colon damage, and better DAI and macroscopic scores. The expression of pro-inflammatory cytokines (TNF-α, IL-6) decreased, while anti-inflammatory cytokine (IL-10) increased compared with WT mice. In vitro, Gpr174^-/- BMDCs showed less maturity, with a declined expression of MHC-II, CD80, CD86 and reduced TNF-α, higher IL-10 after LPS stimulation. Gpr174^-/- BMDCs were less capable of activating OT-II naïve CD4⁺ T cells than WT BMDCs and induced more Th0 cells to differentiate into Treg while less into Th1. Furthermore, the transcriptome sequencing analysis exhibited that Gpr174 participated in TNF-α (NF-κB) signaling, leukocyte transendothelial migration, and Th1/Th2 cell differentiation pathways. Adoptive transfer of Gpr174^-/- BMDCs to WT mice ameliorated DSS-induced colitis.

Conclusion

Our study indicated that GPR174 was involved in the pathogenesis of IBD by regulating the maturation of the dendritic cells to maintain immune homeostasis. TNF-α (NF-κB) signaling pathway, leukocyte transendothelial migration, and Th1/Th2 cell differentiation pathways may be the target pathway.

Leishmania tarentolae as an Antigen Delivery Platform: Dendritic Cell Maturation after Infection with a Clone Engineered to Express the SARS-CoV-2 Spike Protein

Background: Protozoa of the genus Leishmania are characterized by their capacity to target macrophages and Dendritic Cells (DCs). These microorganisms could thus be exploited for the delivery of antigens to immune cells. Leishmania tarentolae is regarded as a non-pathogenic species; it was previously used as a biofactory for protein production and has been considered as a candidate vaccine or as an antigen delivery platform. However, results on the type of immune polarization determined by L. tarentolae are still inconclusive. Methods: DCs were derived from human monocytes and exposed to live L. tarentolae, using both the non-engineered P10 strain, and the same strain engineered for expression of the spike protein from SARS-CoV-2. We then determined: (i) parasite internalization in the DCs; and (ii) the capacity of the assayed strains to activate DCs and the type of immune polarization. Results: Protozoan parasites from both strains were effectively engulfed by DCs, which displayed a full pattern of maturation, in terms of MHC class II and costimulatory molecule expression. In addition, after parasite infection, a limited release of Th1 cytokines was observed. Conclusions: Our results indicate that L. tarentolae could be used as a vehicle for antigen delivery to DCs and to induce the maturation of these cells. The limited cytokine release suggests L. tarentolae as a neutral vaccine vehicle that could be administered in association with appropriate immune-modulating molecules.

CCL19 has potential to be a potential prognostic biomarker and a modulator of tumor immune microenvironment (TIME) of breast cancer: a comprehensive analysis based on TCGA database

The development of cancer was determined by not only the intrinsic properties of cancer cells, but also the communication between cancer cells and tumor microenvironment (TME). We applied ESTIMATE and CIBERSORT algorithms to calculate the immune/stromal component and tumor-infiltrating immune cells (TICs) in TME of BC. The results showed that immune component in TME predicted patients’ survival and associated with progression of BC. Differentially expressed genes (DEGs) were primarily enriched in immune-related activities. Finally, CCL19 was acquired which shared the leading nodes in PPI network and was associated with patients’ survival. High expression of CCL19 predicted better prognosis and participated in progression of BC. Genes in CCL19 up-regulated group were enriched in immune-related activities and these functions might depend on the communications between CCL19 and multiple TICs in TIME. In conclusion, CCL19 functioned as a potential prognostic biomarker and a modulator of TIME in BC through communicating with various TICs.

The Trinity of Skin: Skin Homeostasis as a Neuro-Endocrine-Immune Organ

For a long time, skin was thought to be no more than the barrier of our body. However, in the last few decades, studies into the idea of skin as an independent functional organ have gradually deepened our understanding of skin and its functions. In this review, we gathered evidence that presented skin as a "trinity" of neuro-endocrine-immune function. From a neuro perspective, skin communicates through nerves and receptors, releasing neurotrophins and neuropeptides; from an endocrine perspective, skin is able to receive and secrete most hormones and has the cutaneous equivalent of the hypothalamic-pituitary-adrenal (HPA) axis; from an immune perspective, skin is protected not only by its physical barrier, but also immune cells and molecules, which can also cause inflammation. Together as an organ, skin works bidirectionally by operating peripheral neuro-endocrine-immune function and being regulated by the central nervous system, endocrine system and immune system at the same time, maintaining homeostasis. Additionally, to further explain the "trinity" of cutaneous neuro-endocrine-immune function and how it works in disease pathophysiology, a disease model of rosacea is presented.

Mucosal immune responses to infection and vaccination in the respiratory tract

The lungs are constantly exposed to inhaled debris, allergens, pollutants, commensal or pathogenic microorganisms, and respiratory viruses. As a result, innate and adaptive immune responses in the respiratory tract are tightly regulated and are in continual flux between states of enhanced pathogen clearance, immune-modulation, and tissue repair. New single-cell-sequencing techniques are expanding our knowledge of airway cellular complexity and the nuanced connections between structural and immune cell compartments. Understanding these varied interactions is critical in treatment of human pulmonary disease and infections and in next-generation vaccine design. Here, we review the innate and adaptive immune responses in the lung and airways following infection and vaccination, with particular focus on influenza virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The ongoing SARS-CoV-2 pandemic has put pulmonary research firmly into the global spotlight, challenging previously held notions of respiratory immunity and helping identify new populations at high risk for respiratory distress.

Corneal Dendritic Cell Dynamics Are Associated with Clinical Factors in Type 1 Diabetes

Time-lapsed in vivo corneal confocal microscopy (IVCCM) has shown that corneal dendritic cells (DCs) migrate at approximately 1 µm/min in healthy humans. We have undertaken IVCCM of the whorl region to compare the density of rounded DCs, and DCs with (wDCs) and without (woDCs) dendrites and dynamics; trajectory (length travelled/time), displacement (distance from origin to endpoint/time) speeds and persistence ratio (displacement/trajectory) of woDCs in subjects with type 1 diabetes (T1D) (n = 20) and healthy controls (n = 10). Only the wDC density was higher (p = 0.02) in subjects with T1D compared to controls. There was no significant difference in cell dynamics between subjects with T1D and controls. woDC density correlated directly with HDL cholesterol (r = 0.59, p = 0.007) and inversely with triglycerides (r = −0.61, p = 0.005), whilst round-shaped cell density correlated inversely with HDL cholesterol (r = −0.54, p = 0.007). Displacement, trajectory, and persistency correlated significantly with eGFR (mL/min) (r = 0.74, p < 0.001; r = 0.48, p = 0.031; r = 0.58, p = 0.008, respectively). We show an increase in wDC density but no change in any other DC sub-type or alteration in cell dynamics in T1D. However, there were associations between DC density and lipid parameters and between DC dynamics and renal function. IVCCM provides evidence of a link between immune cell dynamics with lipid levels and renal function.

A nanovaccine for antigen self-presentation and immunosuppression reversal as a personalized cancer immunotherapy strategy

The strategy of combining a vaccine with immune checkpoint inhibitors has been widely investigated in cancer management, but the complete response rate for this strategy is still unresolved. We describe a genetically engineered cell membrane nanovesicle that integrates antigen self-presentation and immunosuppression reversal (ASPIRE) for cancer immunotherapy. The ASPIRE nanovaccine is derived from recombinant adenovirus-infected dendritic cells in which specific peptide-major histocompatibility complex class I (pMHC-I), anti-PD1 antibody and B7 co-stimulatory molecules are simultaneously anchored by a programmed process. ASPIRE can markedly improve antigen delivery to lymphoid organs and generate broad-spectrum T-cell responses that eliminate established tumours. This work presents a powerful vaccine formula that can directly activate both native T cells and exhausted T cells, and suggests a general strategy for personalized cancer immunotherapy.

Tissue-Resident Immune Cells in Humans

Tissue-resident immune cells span both myeloid and lymphoid cell lineages, have been found in multiple human tissues, and play integral roles at all stages of the immune response, from maintaining homeostasis to responding to infectious challenges to resolution of inflammation to tissue repair. In humans, studying immune cells and responses in tissues is challenging, although recent advances in sampling and high-dimensional profiling have provided new insights into the ontogeny, maintenance, and functional role of tissue-resident immune cells. Each tissue contains a specific complement of resident immune cells. Moreover, resident immune cells for each lineage share core properties, along with tissue-specific adaptations. Here we propose a five-point checklist for defining resident immune cell types in humans and describe the currently known features of resident immune cells, their mechanisms of development, and their putative functional roles within various human organs. We also consider these aspects of resident immune cells in the context of future studies and therapeutics.

β2-Integrins - Regulatory and Executive Bridges in the Signaling Network Controlling Leukocyte Trafficking and Migration

Leukocyte trafficking is an essential process of immunity, occurring as leukocytes travel within the bloodstream and as leukocyte migration within tissues. While it is now established that leukocytes can utilize the mesenchymal migration mode or amoeboid migration mode, differences in the migratory behavior of leukocyte subclasses and how these are realized on a molecular level in each subclass is not fully understood. To outline these differences, first migration modes and their dependence on parameters of the extracellular environments will be explained, as well as the intracellular molecular machinery that powers migration in general. Extracellular parameters are detected by adhesion receptors such as integrins. β2-integrins are surface receptors exclusively expressed on leukocytes and are essential for leukocytes exiting the bloodstream, as well as in mesenchymal migration modes, however, integrins are dispensable for the amoeboid migration mode. Additionally, the balance of different RhoGTPases - which are downstream of surface receptor signaling, including integrins - mediate formation of membrane structures as well as actin dynamics. Individual leukocyte subpopulations have been shown to express distinct RhoGTPase profiles along with their differences in migration behavior, which will be outlined. Emerging aspects of leukocyte migration include signal transduction from integrins via actin to the nucleus that regulates DNA status, gene expression profiles and ultimately leukocyte migratory phenotypes, as well as altered leukocyte migration in tumors, which will be touched upon.

Technique integration of single-cell RNA sequencing with spatially resolved transcriptomics in the tumor microenvironment

Background

The tumor microenvironment contributes to tumor initiation, growth, invasion, and metastasis. The tumor microenvironment is heterogeneous in cellular and acellular components, particularly structural features and their gene expression at the inter-and intra-tumor levels.

Main text

Single-cell RNA sequencing profiles single-cell transcriptomes to reveal cell proportions and trajectories while spatial information is lacking. Spatially resolved transcriptomics redeems this lack with limited coverage or depth of transcripts. Hence, the integration of single-cell RNA sequencing and spatial data makes the best use of their strengths, having insights into exploring diverse tissue architectures and interactions in a complicated network. We review applications of integrating the two methods, especially in cellular components in the tumor microenvironment, showing each role in cancer initiation and progression, which provides clinical relevance in prognosis, optimal treatment, and potential therapeutic targets.

Conclusion

The integration of two approaches may break the bottlenecks in the spatial resolution of neighboring cell subpopulations in cancer, and help to describe the signaling circuitry about the intercommunication and its exact mechanisms in producing different types and malignant stages of tumors.

Quantifying the Probing and Selection of Microenvironmental Pores by Motile Immune Cells

Immune cells are constantly on the move through multicellular organisms to explore and respond to pathogens and other harmful insults. While moving, immune cells efficiently traverse microenvironments composed of tissue cells and extracellular fibers, which together form complex environments of various porosity, stiffness, topography, and chemical composition. In this protocol we describe experimental procedures to investigate immune cell migration through microenvironments of heterogeneous porosity. In particular, we describe micro-channels, micro-pillars, and collagen networks as cell migration paths with alternative pore size choices. Employing micro-channels or micro-pillars that divide at junctions into alternative paths with initially differentially sized pores allows us to precisely (1) measure the cellular translocation time through these porous path junctions, (2) quantify the cellular preference for individual pore sizes, and (3) image cellular components like the nucleus and the cytoskeleton. This reductionistic experimental setup thus can elucidate how immune cells perform decisions in complex microenvironments of various porosity like the interstitium. The setup further allows investigation of the underlying forces of cellular squeezing and the consequences of cellular deformation on the integrity of the cell and its organelles. As a complementary approach that does not require any micro-engineering expertise, we describe the usage of three-dimensional collagen networks with different pore sizes. Whereas we here focus on dendritic cells as a model for motile immune cells, the described protocols are versatile as they are also applicable for other immune cell types like neutrophils and non-immune cell types such as mesenchymal and cancer cells. In summary, we here describe protocols to identify the mechanisms and principles of cellular probing, decision making, and squeezing during cellular movement through microenvironments of heterogeneous porosity. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Immune cell migration in micro-channels and micro-pillars with defined pore sizes Support Protocol 1: Epoxy replica of generated and/or published micro-structures Support Protocol 2: Dendritic cell differentiation Basic Protocol 2: Immune cell migration in 3D collagen networks of variable pore sizes.

miR-155: An Important Role in Inflammation Response

MicroRNAs (miRNAs) are a class of small, mature, noncoding RNA that lead to posttranscriptional gene silencing to regulate gene expression. miRNAs are instrumental in biological processes such as cell development, cell differentiation, cell proliferation, and cell apoptosis. The miRNA-mediated gene silencing is an important part of the regulation of gene expression in many kinds of diseases. miR-155, one of the best-characterized miRNAs, has been found to be closely related to physiological and pathological processes. What is more, miR-155 can be used as a potential therapeutic target for inflammatory diseases. We analyze the articles about miR-155 for nearly five years, review the advanced study on the function of miR-155 in different inflammatory cells like T cells, B cells, DCs, and macrophages, and then summarize the biological functions of miR-155 in different inflammatory cells. The widespread involvement of miR-155 in human diseases has led to a novel therapeutic approach between Chinese and Western medicine.

Cell migration orchestrates migrasome formation by shaping retraction fibers

Migrasomes are recently discovered vesicle-like structures on retraction fibers of migrating cells that have been linked with transfer of cellular contents, shedding of unwanted materials, and information integration. However, whether and how the cell migration paradigm regulates migrasome formation is not clear. Here, we report that there are significantly fewer migrasomes in turning cells compared with straight persistently migrating cells. The major insight underlying this observation is that as the cells elongate, their rear ends become narrower, subsequently resulting in fewer retraction fibers during impersistent migration. In addition to migration persistence, we reveal that migration speed positively corelates with migrasome formation, owing to the derived length of retraction fibers. Substantiating our hypothesis, genetically removing vimentin compromises cell migration speed and persistence and leads to fewer migrasomes. Together, our data explicate the critical roles of two cell migration patterns, persistence and speed, in the control of migrasome formation by regulating retraction fibers.

MALAT1 Induces Food Allergy by Promoting Release of IL-6 from Dendritic Cells and Suppressing the Immunomodulatory Function of Tregs

Background

Dendritic cells (DCs) comprise a valuable target for immune-modulation in food allergy (FA). Long noncoding RNA (lncRNA), metastasis associated lung adenocarcinoma transcript 1 (MALAT1) has immunomodulatory capacities and may influence the outcome of DC antigen presentation. However, the precise molecular mechanisms underlying the implication of MALAT1 in FA remain unclear.

Methods

BALB/c mice were sensitized to ovalbumin in accordance with a model of FA protocol and injected with adenovirus. After modeling, immunohistochemistry was performed to analyze the jejunal tissues of FA mice and hematoxylin-eosin staining and toluidine blue staining were performed to detect inflammation and mast cell numbers. Ovalbumin-sensitized mice were monitored for symptoms of diarrhea and rectal temperature. Immature DCs were stimulated by oxidized low density lipoprotein to trigger their maturation.

Results

MALAT1 was found highly expressed in mice with FA, and its silencing relieved allergic reactions with reduction in intestinal inflammatory cells and mast cells in FA mice. MALAT1 aggravated symptoms by downregulating zinc finger protein 36 (ZFP36). MALAT1 also downregulated ZFP36 expression to promote interleukin-6 (IL-6) secretion by DCs and maturation of DCs, with increased serum-specific immunoglobulin E (IgE) and IgG1 levels.

Conclusion

Together, these data suggested that therapeutically blocking MALAT1 in FA could reduce the severity of FA by decreasing secretion of IL-6 by DCs and suppressing the immunomodulation of Tregs.

The relationship between peripheral immune response and disease severity in SARS-CoV-2-infected subjects: A cross-sectional study

Coronavirus disease 2019 (COVID-19) is a respiratory infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and marked by an intense inflammatory response and immune dysregulation in the most severe cases. In order to better clarify the relationship between peripheral immune system changes and the severity of COVID-19, this study aimed to evaluate the frequencies and absolute numbers of peripheral subsets of neutrophils, monocytes, and dendritic cells (DCs), in addition to quantifying the levels of inflammatory mediators. One hundred fifty-seven COVID-19 patients were stratified into mild, moderate, severe, and critical disease categories. The cellular components and circulating cytokines were assessed by flow cytometry. Nitric oxide (NOx) and myeloperoxidase (MPO) levels were measured by colourimetric tests. COVID-19 patients presented neutrophilia, with signs of emergency myelopoiesis. Alterations in the monocytic component were observed in patients with moderate to critical illness, with an increase in classical monocytes and a reduction in nonclassical monocytes, in addition to a reduction in the expression of HLA-DR in all subtypes of monocytes, indicating immunosuppression. DCs, especially plasmacytoid DCs, also showed a large reduction in moderate to critical patients. COVID-19 patients showed an increase in MPO, interleukin (IL)-12, IL-6, IL-10, and IL-8, accompanied by a reduction in IL-17A and NOx. IL-10 levels ≥14 pg/ml were strongly related to the worst outcome, with a sensitivity of 78·3% and a specificity of 79·1%. The results of this study indicate the presence of systemic effects induced by COVID-19, which appear to be related to the pathophysiology of the disease, highlighting the potential of IL-10 as a possible prognostic biomarker for COVID-19.

Cellular, Antibody and Cytokine Pathways in Children with Acute SARS-CoV-2 Infection and MIS-C-Can We Match the Puzzle?

The newly identified strain of the Coronaviridae family called severe acute respiratory syndrome (SARS-CoV-2) recently became the most significant health threat for adults and children. Some main predictors of severe clinical course in patients with SARS-CoV-2 infection are age and concomitant health conditions. Therefore, the proper evaluation of SARS-CoV-2-specific immunity is urgently required to understand and predict the spectrum of possible clinical phenotypes and recommend vaccination options and regimens in children. Furthermore, it is critical to characterize the nature of SARS-CoV-2-specific immune responses in children following asymptomatic infection and COVID-19 and other related conditions such as multisystem inflammatory syndrome (MIS-C), para-infectious and late postinfectious consequences. Recent studies involving children revealed a variety of cytokines, T cells and antibody responses in the pathogenesis of the disease. Moreover, different clinical scenarios in children were observed-asymptomatic seroprevalence, acute SARS-CoV-2 infection, and rarely severe COVID-19 with typical cytokine storm, MIS-C, long COVID-19, etc. Therefore, to gain a better clinical view, adequate diagnostic criteria and treatment algorithms, it is essential to create a realistic picture of the immunological puzzle of SARS-CoV-2 infection in different age groups. Finally, it was demonstrated that children may exert a potent and prolonged adaptive anti-SARS-CoV-2 immune response, with significant cross-reactions against other human Corona Viruses, that might contribute to disease sparing effect in this age range. However, the immunopathology of the virus has to be elucidated first.

Chemical and Biomolecular Strategies for STING Pathway Activation in Cancer Immunotherapy

The stimulator of interferon genes (STING) cellular signaling pathway is a promising target for cancer immunotherapy. Activation of the intracellular STING protein triggers the production of a multifaceted array of immunostimulatory molecules, which, in the proper context, can drive dendritic cell maturation, antitumor macrophage polarization, T cell priming and activation, natural killer cell activation, vascular reprogramming, and/or cancer cell death, resulting in immune-mediated tumor elimination and generation of antitumor immune memory. Accordingly, there is a significant amount of ongoing preclinical and clinical research toward further understanding the role of the STING pathway in cancer immune surveillance as well as the development of modulators of the pathway as a strategy to stimulate antitumor immunity. Yet, the efficacy of STING pathway agonists is limited by many drug delivery and pharmacological challenges. Depending on the class of STING agonist and the desired administration route, these may include poor drug stability, immunocellular toxicity, immune-related adverse events, limited tumor or lymph node targeting and/or retention, low cellular uptake and intracellular delivery, and a complex dependence on the magnitude and kinetics of STING signaling. This review provides a concise summary of the STING pathway, highlighting recent biological developments, immunological consequences, and implications for drug delivery. This review also offers a critical analysis of an expanding arsenal of chemical strategies that are being employed to enhance the efficacy, safety, and/or clinical utility of STING pathway agonists and lastly draws attention to several opportunities for therapeutic advancements.

Circular gap forming device and two-dimensional area calculation for in vitro cell migration study

Cell wound healing assay is an important experimental technique for the detection of cell migration in vitro. At present, scratch on monolayer cells using a pipette tip is commonly used. However, it is difficult to guarantee the scratch with same width, and only the migration distance of a certain part is calculated. Therefore, the experimental method needs to be optimized. ATRA was used to treat hepa1-6 mouse hepatoma cells. Circular wound with diameter of 0.2 cm were formed by a circular gap forming device. The whole cell wound region could be captured under the microscope to observe cell migration. There are almost no crawling cells in the wound region. The migration capacity of hepa1-6 cells was evaluated by calculating the healing area. ATRA could significantly inhibit the migration of hepa1-6 cells. Compared with linear wound, the standard deviation of wound healing rate in the circular cell wound method is smaller. The circular cell wound method can ensure the dynamic observation of the same wound region, and calculate the healing area at the two-dimensional level with small error and high repetition rate. It is reliable and easy to operate, can be widely used in laboratory.

Delivery of mRNA for regulating functions of immune cells

Abnormal immune cell functions are commonly related to various diseases, including cancer, autoimmune diseases, and infectious diseases. Messenger RNA (mRNA)-based therapy can regulate the functions of immune cells or assign new functions to immune cells, thereby generating therapeutic immune responses to treat these diseases. However, mRNA is unstable in physiological environments and can hardly enter the cytoplasm of target cells; thus, effective mRNA delivery systems are critical for developing mRNA therapy. The two mRNA vaccines of Pfizer-BioNTech and Moderna have demonstrated that lipid nanoparticles (LNPs) can deliver mRNA into dendritic cells (DCs) to induce immunization against severe acute respiratory syndrome coronavirus 2, which opened the floodgates to the development of mRNA therapy. Apart from DCs, other immune cells are promising targets for mRNA therapy. This review summarized the barriers to mRNA delivery and advances in mRNA delivery for regulating the functions of different immune cells.

An Experimental Model of Neuro-Immune Interactions in the Eye: Corneal Sensory Nerves and Resident Dendritic Cells

The cornea is an avascular connective tissue that is crucial, not only as the primary barrier of the eye but also as a proper transparent refractive structure. Corneal transparency is necessary for vision and is the result of several factors, including its highly organized structure, the physiology of its few cellular components, the lack of myelinated nerves (although it is extremely innervated), the tightly controlled hydration state, and the absence of blood and lymphatic vessels in healthy conditions, among others. The avascular, immune-privileged tissue of the cornea is an ideal model to study the interactions between its well-characterized and dense sensory nerves (easily accessible for both focal electrophysiological recording and morphological studies) and the low number of resident immune cell types, distinguished from those cells migrating from blood vessels. This paper presents an overview of the corneal structure and innervation, the resident dendritic cell (DC) subpopulations present in the cornea, their distribution in relation to corneal nerves, and their role in ocular inflammatory diseases. A mouse model in which sensory axons are constitutively labeled with tdTomato and DCs with green fluorescent protein (GFP) allows further analysis of the neuro-immune crosstalk under inflammatory and steady-state conditions of the eye.