Plasma Transfusion Promoted Reprogramming CD4+ T Lymphocytes Immune Response in Severe Sepsis Mice Model Through Modulating the Exosome Protein Galectin 9

Epithelial-derived galectin-9 containing exosomes contribute to the immunomodulatory effects promoted by 2'-fucosyllactose and short-chain galacto- and long-chain fructo-oligosaccharides

Introduction

Early life exposure to non-digestible oligosaccharides (NDO) or microbial components is known to affect immune development. NDO in combination with a TLR9 agonist mimicking bacterial triggers (CpG) promoted the secretion of galectins through unknown pathways. We aimed to study the contribution of exosomes in epithelial galectin secretion and subsequent immunoregulation upon exposure to a mixture of NDO by inhibiting exosome biogenesis.

Methods

Human intestinal epithelial cells (IEC) (FHs 74 Int or HT-29) were apically exposed to 2'-fucosyllactose (2'FL) and short-chain galacto- and long-chain fructo-oligosaccharides (GF), alone or with CpG. Basolaterally, non-activated or αCD3/CD28-activated peripheral blood mononuclear cells (PBMC) were added. After 24 h incubation, IEC were washed and incubated in fresh medium to analyze epithelial-derived galectin secretion. Additionally, before exposure to NDO and CpG, IEC were exposed to GW4869 to inhibit exosome biogenesis. After 24 h of incubation, IEC were washed and incubated for additional 24 h in the presence of GW4869, after which epithelial-derived galectin secretion was studied. Also, epithelial-derived exosomes were isolated to study the presence of galectins within the exosomes.

Results

Compared to CpG alone, exposure to 2'FL/GF mixture and CpG, significantly enhanced Th1-type IFNγ, and regulatory IEC-derived galectin-9 secretion in the HT-29/PBMC model. Similarly, in the FHs 74 Int/PBMC co-culture, 2'FL/GF induced immunomodulatory effects in the absence of CpG. Interestingly, galectin-9 and -4 were present in CD63-expressing exosomes isolated from HT-29 supernatants after IEC/PBMC co-culture. Exposure to GW4869 suppressed 2'FL/GF and CpG induced epithelial-derived galectin-9 secretion, which subsequently prevented the rise in IL-10 and reduction in IL-13 secretion observed in the HT-29/PBMC co-culture model upon exposure to 2'FL/GF and CpG.

Discussion

Exposure to 2'FL/GF and CpG or 2'FL/GF promoted Th1-type regulatory effects in HT-29/PBMC or FHs 74 Int/PBMC co-culture respectively, while Th2-type IL-13 was reduced in association with increased galectin-9 release. Galectin-9 and -4 were present in exosomes from HT-29 and the inhibition of exosome biogenesis inhibited epithelial-derived galectin secretion. This, also affected immunomodulatory effects in IEC/PBMC co-culture suggesting a key role of galectin expressing IEC-derived exosomes in the mucosal immune regulation induced by NDO.

Regulatory T Cells: Angels or Demons in the Pathophysiology of Sepsis?

Sepsis is a syndrome characterized by life-threatening organ dysfunction caused by the dysregulated host response to an infection. Sepsis, especially septic shock and multiple organ dysfunction is a medical emergency associated with high morbidity, high mortality, and prolonged after-effects. Over the past 20 years, regulatory T cells (Tregs) have been a key topic of focus in all stages of sepsis research. Tregs play a controversial role in sepsis based on their heterogeneous characteristics, complex organ/tissue-specific patterns in the host, the multi-dimensional heterogeneous syndrome of sepsis, the different types of pathogenic microbiology, and even different types of laboratory research models and clinical research methods. In the context of sepsis, Tregs may be considered both angels and demons. We propose that the symptoms and signs of sepsis can be attenuated by regulating Tregs. This review summarizes the controversial roles and Treg checkpoints in sepsis.

Exosome-mediated stable epigenetic repression of HIV-1

Human Immunodeficiency Virus (HIV-1) produces a persistent latent infection. Control of HIV-1 using combination antiretroviral therapy (cART) comes at the cost of life-shortening side effects and development of drug-resistant HIV-1. An ideal and safer therapy should be deliverable in vivo and target the stable epigenetic repression of the virus, inducing a stable "block and lock" of virus expression. Towards this goal, we developed an HIV-1 promoter-targeting Zinc Finger Protein (ZFP-362) fused to active domains of DNA methyltransferase 3 A to induce long-term stable epigenetic repression of HIV-1. Cells were engineered to produce exosomes packaged with RNAs encoding this HIV-1 repressor protein. We find here that the repressor loaded anti-HIV-1 exosomes suppress virus expression and that this suppression is mechanistically driven by DNA methylation of HIV-1 in humanized NSG mouse models. The observations presented here pave the way for an exosome-mediated systemic delivery platform of therapeutic cargo to epigenetically repress HIV-1 infection.

HDAC1 potentiates CD4 + T cell activation by inhibiting miR-124 and promoting IRF1 in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease leading to considerable morbidity worldwide, which can be developed from a breakdown in immunological tolerance, resulting in T cell hyperactivation. T cell hyperactivation has been implicated in the tissue damage associated with many diseases. Although many researchers have identified the involvement of T-cell receptor-associated signaling molecules in T-cell activation, the mechanisms underlying this process are yet to be elaborated. In the current study, we set out to reveal a novel transcriptional mechanism required for CD4 + T cell immunoactivity involved in SLE. First of all, miR-124 was experimentally determined to be under-expressed in peripheral blood samples of SLE patients relative to healthy individuals. We further isolated CD4 + T cells from the peripheral blood samples of SLE patients and healthy individuals, and found that miR-124 was poorly expressed in peripheral blood-derived CD4 + T cells of SLE patients. Subsequent experiments demonstrated that re-expression of miR-124 inhibited the immunoactivity of CD4 + T cells from SLE patients, which was achieved through the down-regulation of IRF1 since dual-luciferase reporter gene assay findings indicated that miR-124 could target IRF1. In addition, HDAC1 was found to be enriched at the miR-124 promoter resulting in inhibition of miR-124 expression, thereby promoting the immunoactivity of CD4 + T cells. In conclusion, we identify that as a stimulator of CD4 + T cell immunoactivity, HDAC1 may be implicated in the immunopathology of SLE. The study will open up new avenues to explore future immunotherapy strategies for SLE.