The mRNA-LNP vaccines - the good, the bad and the ugly?

The mRNA-LNP vaccine has received much attention during the COVID-19 pandemic since it served as the basis of the most widely used SARS-CoV-2 vaccines in Western countries. Based on early clinical trial data, these vaccines were deemed safe and effective for all demographics. However, the latest data raise serious concerns about the safety and effectiveness of these vaccines.

Dendritic cells overcome Cre/Lox induced gene deficiency by siphoning cytosolic material from surrounding cells.

In a previous report, keratinocytes were shown to share their gene expression profile with surrounding Langerhans cells (LCs), influencing LC biology. Here, we investigated whether transferred material could substitute for lost gene products in cells subjected to Cre/Lox conditional gene deletion. We found that in human Langerin-Cre mice, epidermal LCs and CD11b+CD103+ mesenteric DCs overcome gene deletion if the deleted gene was expressed by neighboring cells.

Dendritic Cells Overcome Cre/Lox Induced Gene Deficiency by Siphoning Material From Neighboring Cells Using Intracellular Monitoring-a Novel Mechanism of Antigen Acquisition.

Macrophages and dendritic cells (DCs) in peripheral tissue interact closely with their local microenvironment by scavenging protein and nucleic acids released by neighboring cells. Material transfer between cell types is necessary for pathogen detection and antigen presentation, but thought to be relatively limited in scale. Recent reports, however, demonstrate that the quantity of transferred material can be quite large when DCs are in direct contact with live cells.

Intracellular monitoring by dendritic cells - a new way to stay informed - from a simple scavenger to an active gatherer.

Dendritic cells (DCs) are required for the initiation of the adaptive immune response. Their ability to acquire antigens in the periphery is a critical step in this process. DCs express a wide variety of adhesion molecules and possess an extremely fluid plasma membrane that facilitates scavenging the extracellular environment and capturing material like exosomes, apoptotic bodies, and pathogens.

Local IL-23 is required for proliferation and retention of skin-resident memory T17 cells.

The cytokine interleukin-23 (IL-23) is critical for development and maintenance of autoimmune inflammation in nonlymphoid tissues; however, the mechanism through which IL-23 supports tissue-specific immunity remains unclear. In mice, we found that circulating memory T cells were dispensable for anamnestic protection from skin infection, and tissue-resident memory (T) cell-mediated protection from reinfection required IL-23. Administration of anti-IL-23 receptor antibody to mice after resolution of primary infection resulted in loss of CD69 CD103 tissue-resident memory T helper 17 (T) cells from skin, and clinical anti-IL-23 therapy depleted T cells from skin of patients with psoriasis.

Pre-exposure to mRNA-LNP inhibits adaptive immune responses and alters innate immune fitness in an inheritable fashion.

Hundreds of millions of SARS-CoV-2 mRNA-LNP vaccine doses have already been administered to humans. However, we lack a comprehensive understanding of the immune effects of this platform. The mRNA-LNP-based SARS-CoV-2 vaccine is highly inflammatory, and its synthetic ionizable lipid component responsible for the induction of inflammation has a long in vivo half-life.

Pre-exposure to mRNA-LNP inhibits adaptive immune responses and alters innate immune fitness in an inheritable fashion.

Unlabelled: Hundreds of millions of SARS-CoV-2 mRNA-LNP vaccine doses have already been administered to humans. However, we lack a comprehensive understanding of the immune effects of this platform. The mRNA-LNP-based SARS-CoV-2 vaccine is highly inflammatory, and its synthetic ionizable lipid component responsible for the induction of inflammation has a long half-life.

"Don't Look Up" Your Science-Herd Immunity or Herd Mentality?

This analysis piece will attempt to examine some of the critical pandemic-related measures implemented in the United States from an immunological perspective and pinpoint caveats that should have been considered before their implementation. I also discuss alternative measures grounded in scientific data that were not thoroughly explored and likely could have helped fight the pandemic.

Antibody-Mediated Targeting of a Hybrid Insulin Peptide Toward Neonatal Thymic Langerin-Positive Cells Enhances T-Cell Central Tolerance and Delays Autoimmune Diabetes.

Thymic presentation of self-antigens is critical for establishing a functional yet self-tolerant T-cell population. Hybrid peptides formed through transpeptidation within pancreatic β-cell lysosomes have been proposed as a new class of autoantigens in type 1 diabetes (T1D). While the production of hybrid peptides in the thymus has not been explored, due to the nature of their generation, it is thought to be highly unlikely.

Single-cell suspension preparation from murine organs following mRNA-LNP exposure.

We describe a protocol to study inflammatory responses triggered by the mRNA-lipid nanoparticle (LNP) vaccine formulations in skin, muscle, and lung and the adaptive immune responses induced in the draining lymph nodes. Here, we will present how to deliver these reagents through intradermal, intramuscular, and intranasal routes, generating single-cell suspensions from the inoculated and target organs for downstream analyses. For complete details on the use and execution of this protocol, please refer to Ndeupen et al.

Anti-CD40 Antibody Fused to CD40 Ligand Is a Superagonist Platform for Adjuvant Intrinsic DC-Targeting Vaccines.

CD40 is a potent activating receptor expressed on antigen-presenting cells (APCs) of the immune system. CD40 regulates many aspects of B and T cell immunity interaction with CD40L expressed on activated T cells. Targeting antigens to CD40 agonistic anti-CD40 antibody fusions promotes both humoral and cellular immunity, but current anti-CD40 antibody-antigen vaccine prototypes require co-adjuvant administration for significant  efficacy.

Langerhans cells and cDC1s play redundant roles in mRNA-LNP induced protective anti-influenza and anti-SARS-CoV-2 immune responses.

Nucleoside modified mRNA combined with Acuitas Therapeutics' lipid nanoparticles (LNPs) has been shown to support robust humoral immune responses in many preclinical animal vaccine studies and later in humans with the SARS-CoV-2 vaccination. We recently showed that this platform is highly inflammatory due to the LNPs' ionizable lipid component. The inflammatory property is key to support the development of potent humoral immune responses.

The mRNA-LNP platform's lipid nanoparticle component used in preclinical vaccine studies is highly inflammatory.

Vaccines based on mRNA-containing lipid nanoparticles (LNPs) are a promising new platform used by two leading vaccines against COVID-19. Clinical trials and ongoing vaccinations present with varying degrees of protection levels and side effects. However, the drivers of the reported side effects remain poorly defined.

Anti-CD40 Antibodies Fused to CD40 Ligand Have Superagonist Properties.

CD40 is a potent activating receptor within the TNFR family expressed on APCs of the immune system, and it regulates many aspects of B and T cell immunity via interaction with CD40 ligand (CD40L; CD154) expressed on the surface of activated T cells. Soluble CD40L and agonistic mAbs directed to CD40 are being explored as adjuvants in therapeutic or vaccination settings. Some anti-CD40 Abs can synergize with soluble monomeric CD40L.

Langerhans cells and cDC1s play redundant roles in mRNA-LNP induced protective anti-influenza and anti-SARS-CoV-2 responses.

Nucleoside modified mRNA combined with Acuitas Therapeutics' lipid nanoparticles (LNP) have been shown to support robust humoral immune responses in many preclinical animal vaccine studies and later in humans with the SARS-CoV-2 vaccination. We recently showed that this platform is highly inflammatory due to the LNPs' ionizable lipid component. The inflammatory property is key to support the development of potent humoral immune responses.

Targeting human langerin promotes HIV-1 specific humoral immune responses.

The main avenue for the development of an HIV-1 vaccine remains the induction of protective antibodies. A rationale approach is to target antigen to specific receptors on dendritic cells (DC) via fused monoclonal antibodies (mAb). In mouse and non-human primate models, targeting of skin Langerhans cells (LC) with anti-Langerin mAbs fused with HIV-1 Gag antigen drives antigen-specific humoral responses.

Future considerations for the mRNA-lipid nanoparticle vaccine platform.

Vaccines based on mRNA-containing lipid nanoparticles (LNPs) pioneered by Katalin Karikó and Drew Weissman at the University of Pennsylvania are a promising new vaccine platform used by two of the leading vaccines against coronavirus disease in 2019 (COVID-19). However, there are many questions regarding their mechanism of action in humans that remain unanswered. Here we consider the immunological features of LNP components and off-target effects of the mRNA, both of which could increase the risk of side effects.

The mRNA-LNP platform's lipid nanoparticle component used in preclinical vaccine studies is highly inflammatory.

Vaccines based on mRNA-containing lipid nanoparticles (LNPs) are a promising new platform used by two leading vaccines against coronavirus disease in 2019 (COVID-19). Clinical trials and ongoing vaccinations present with very high protection levels and varying degrees of side effects. However, the nature of the reported side effects remains poorly defined.

Brief communication: Long-term absence of Langerhans cells alters the gene expression profile of keratinocytes and dendritic epidermal T cells.

Tissue-resident and infiltrating immune cells are continuously exposed to molecules derived from the local cells that often come in form of secreted factors, such as cytokines. These factors are known to impact the immune cells' biology. However, very little is known about whether the tissue resident immune cells in return also affect the local environment.

One-step artificial antigen presenting cell-based vaccines induce potent effector CD8 T cell responses.

The production and wide use of artificial antigen presenting cells (aAPCs) in the clinic as cancer immunotherapeutics are hindered by the need of identifying immunogenic cancer antigens and production of recombinant patient-specific major histocompatibility complexes (MHC) loaded with these peptides. To overcome these limitations, in this study, we tested the idea of whether peptide-MHCs can directly be captured from cell lysates, including cancer cells using affinity beads, and used to initiate T cell responses. In theory, these affinity beads covered with the unknown peptide-MHC repertoire captured from the cancer cells could interact with a wide range of antigen-specific T cells and promote anti-cancer responses.

DC Subsets Regulate Humoral Immune Responses by Supporting the Differentiation of Distinct Tfh Cells.

To determine the contribution of skin DC subsets in the regulation of humoral immunity, we used a well-characterized antigen targeting system to limit antigen availability and presentation to certain skin-derived DC subsets. Here we show that delivery of foreign antigen to steady state Langerhans cells (LCs) and cDC1s through the same receptor (Langerin) led to, respectively, robust vs. minimal-to-null humoral immune response.

Keratinocytes Share Gene Expression Fingerprint with Epidermal Langerhans Cells via mRNA Transfer.

The immune functions of epithelia-resident dendritic cells are influenced by epithelial-derived cytokines. Here we identified a communication form between tissue-resident dendritic cells and niche cells that allows direct intracellular material exchange between the parties. We show that many keratinocyte (KC)-specific molecules such as keratins and adhesion molecules could be detected in the epidermal-resident Langerhans cells (LCs) as mRNA and protein.

Stromal cells control the epithelial residence of DCs and memory T cells by regulated activation of TGF-β.

Cells of the immune system that reside in barrier epithelia provide a first line of defense against pathogens. Langerhans cells (LCs) and CD8(+) tissue-resident memory T cells (TRM cells) require active transforming growth factor-β1 (TGF-β) for epidermal residence. Here we found that integrins αvβ6 and αvβ8 were expressed in non-overlapping patterns by keratinocytes (KCs) and maintained the epidermal residence of LCs and TRM cells by activating latent TGF-β.

Skin dendritic cells induce follicular helper T cells and protective humoral immune responses.

Background: The contribution of individual subsets of dendritic cells (DCs) to generation of adaptive immunity is central to understanding immune homeostasis and protective immune responses.

Objective: We sought to define functions for steady-state skin DCs.

Methods: We present an approach in which we restrict antigen presentation to individual DC subsets in the skin and monitor the effects on endogenous antigen-specific CD4(+) T- and B-cell responses.

Quantifying Memory CD8 T Cells Reveals Regionalization of Immunosurveillance.

Memory CD8 T cells protect against intracellular pathogens by scanning host cell surfaces; thus, infection detection rates depend on memory cell number and distribution. Population analyses rely on cell isolation from whole organs, and interpretation is predicated on presumptions of near complete cell recovery. Paradigmatically, memory is parsed into central, effector, and resident subsets, ostensibly defined by immunosurveillance patterns but in practice identified by phenotypic markers.