Essential role of NK cells in IgG therapy for experimental autoimmune encephalomyelitis

Immunomodulation for Tissue Repair and Regeneration

Various immune cells participate in repair and regeneration following tissue injury or damage, orchestrating tissue inflammation and regeneration processes. A deeper understanding of the immune system's involvement in tissue repair and regeneration is critical for the development of successful reparatory and regenerative strategies. Here we review recent technologies that facilitate cell-based and biomaterial-based modulation of the immune systems for tissue repair and regeneration. First, we summarize the roles of various types of immune cells in tissue repair. Second, we review the principle, examples, and limitations of regulatory T (Treg) cell-based therapy, a representative cell-based immunotherapy. Finally, we discuss biomaterial-based immunotherapy strategies that aim to modulate immune cells using various biomaterials for tissue repair and regeneration.

The Role of CD4+ T Cells in the Immunotherapy of Brain Disease by Secreting Different Cytokines

Upon different stimulation, naïve CD4⁺ T cells differentiate into various subsets of T helper (Th) cells, including Th1, Th2, Th17, and Tregs. They play both protective and pathogenic roles in the central nervous system (CNS) by secreting different cytokines. Failure of the homeostasis of the subgroups in the CNS can result in different brain diseases. Recently, immunotherapy has drawn more and more attention in the therapy of various brain diseases. Here, we describe the role of different CD4⁺ T cell subsets and their secreted cytokines in various brain diseases, as well as the ways in which by affecting CD4⁺ T cells in therapy of the CNS diseases. Understanding the role of CD4⁺ T cells and their secreted cytokines in the immunotherapy of brain disease will provide new targets and therapeutics for the treatment of brain disease. The role of CD4 + T cell subtypes in different diseases and their associated regulatory genes, proteins, and enzymes. CD4 + T cell subtypes play both protective (green) and pathogenic (red) roles in different brain diseases. The immune regulatory effects of CD4 + T cells and their subtypes are promoted or inhibited by different genes, proteins, and enzymes.

High Dose Intravenous IgG Therapy Modulates Multiple NK Cell and T Cell Functions in Patients With Immune Dysregulation

Intravenous immunoglobulin (IVIG) is an effective immunomodulatory treatment for immune dysregulation diseases. However, the mechanisms by which it reduces systemic inflammation are not well understood. NK cell cytotoxicity is decreased by IVIG in women with reduced fertility, but IVIG effects on NK cells in immune dysregulation are less clear. We hypothesized that IVIG modulation of lymphocyte function, especially in NK cells, is important for resolution of inflammation. Our aim was to identify IVIG-induced changes in a cohort of patients with Kawasaki disease (KD) and those that occur broadly in pediatric patients with various immune dysregulatory diseases. Peripheral blood mononuclear cells (PBMCs) of patients with KD or autoimmune/inflammatory diseases were phenotyped pre and post high dose IVIG treatment by flow cytometry. In KD patients, after IVIG infusion T_reg cell frequency and the proportion of activated CD25⁺ immunoregulatory CD56^bright NK cells was increased, and multiple lymphocyte subsets showed increased expression of the lymphoid tissue homing receptor CD62L. Importantly, IVIG treatment decreased the frequency of cells expressing the degranulation marker CD107a among cytotoxic CD56^dim NK cells, which was reflected in a significant reduction in target cell killing and in decreased production of multiple pro-inflammatory mediators. Interestingly, the activating receptor CD336 was expressed on a higher proportion of CD56^bright NK cells after IVIG in both KD and autoimmune/inflammatory patients while other NK receptors were increased differentially in each cohort. In autoimmune/inflammatory patients IVIG induced the proliferation marker CD71 on a higher percentage of CD56^dim NK cells, and in contrast to KD patients, CD107a⁺ cells were increased in this subset. Furthermore, when PBMCs were stimulated ex vivo with IL-2 or Candida antigen in autologous plasma, more of the CD4⁺ T cells of KD patients expressed CD25 after IVIG therapy but fewer cytotoxic T cells were degranulated based on CD107a expression. In summary, IVIG treatment in patients with immune dysregulation has multiple effects, especially on NK cell subsets and CD4⁺ T cells, which are compatible with promoting resolution of inflammation. These novel findings provide insight into the immunomodulatory actions of IVIG in autoimmune and inflammatory conditions.

NK cell markers predict the efficacy of IV immunoglobulins in CIDP

Objective

To assess whether IV immunoglobulins (IVIgs) as a first-line treatment for chronic inflammatory demyelinating polyneuropathy (CIDP) have a regulative effect on natural killer (NK) cells that is related to clinical responsiveness to IVIg.

Methods

In a prospective longitudinal study, we collected blood samples of 29 patients with CIDP before and after initiation of IVIg treatment for up to 6 months. We used semiquantitative PCR and flow cytometry in the peripheral blood to analyze the effects of IVIg on the NK cells. The results were correlated with clinical aspects encompassing responsiveness.

Results

We found a reduction in the expression of several typical NK cell genes 1 day after IVIg administration. Flow cytometry furthermore revealed a reduced cytotoxic CD56^dim NK cell population, whereas regulatory CD56^bright NK cells remained mostly unaffected or were even increased after IVIg treatment. Surprisingly, the observed effects on NK cells almost exclusively occurred in IVIg-responsive patients with CIDP.

Conclusions

The correlation between the altered NK cell population and treatment efficiency suggests a crucial role for NK cells in the still speculative mode of action of IVIg treatment. Analyzing NK cell subsets after 24 hours of treatment initiation appeared as a predictive marker for IVIg responsiveness. Further studies are warranted investigating the potential of NK cell status as a routine parameter in patients with CIDP before IVIg therapy.

Classification of evidence

This study provides Class I evidence that NK cell markers predict clinical response to IVIg in patients with CIDP.

KIR2DL4-HLAG interaction at human NK cell-oligodendrocyte interfaces regulates IFN-γ-mediated effects

Interactions between germline-encoded natural killer (NK) cell receptors and their respective ligands on tumorigenic or virus-infected cells determine NK cell cytotoxic activity and/or cytokine secretion. NK cell cytokine responses can be augmented in and can potentially contribute to multiple sclerosis (MS), an inflammatory disease of the central nervous system focused upon the oligodendrocytes (OLs). To investigate mechanisms by which NK cells may contribute to MS pathogenesis, we developed an in vitro human model of OL-NK cell interaction. We found that activated, but not resting human NK cells form conjugates with, and mediate cytotoxicity against, human oligodendrocytes. NK cells, when in conjugate with OLs, rapidly synthesize and polarize IFN-γ toward the OLs. IFN-γ  is capable of reducing myelin oligodendrocyte and myelin associated glycoproteins (MOG and MAG) content. This activity is independent of MHC class-I mediated inhibition via KIR2DL1, but dependent upon the interaction between NK cell-expressed KIR2DL4 and its oligodendrocyte-expressed ligand, HLA-G. NK cells from patients with MS express higher levels of IFN-γ following conjugation to OLs, more actively promote in vitro reduction of MOG and MAG and have higher frequencies of the KIR2DL4 positive population. These data collectively suggest a mechanism by which NK cells can promote pathogenic effects upon OLs.

Interleukin-33 deficiency exacerbated experimental autoimmune encephalomyelitis with an influence on immune cells and glia cells

Interleukin (IL)-33, a member of the IL-1 cytokine family, is highly expressed in central nervous system (CNS), suggesting its potential role in CNS. Although some studies have focused on the role of IL-33 in multiple sclerosis (MS) / experimental autoimmune encephalomyelitis (EAE), an autoimmune disease characterized by demyelination and axonal damage in CNS, the exact role of IL-33 in MS/EAE remains unclear and controversial. Here, we used IL-33 knockout mice to clarify the role of endogenous IL-33 in EAE by simultaneously eliminating its role as a nuclear transcription factor and an extracellular cytokine. We found that the clinical score in IL-33 knockout EAE mice was higher accompanied by more severe demyelination compared with the wild-type (WT) EAE mice. As for the main immune cells participating in EAE in IL-33 knockout mice, pathogenic effector T cells increased both in peripheral immune organs and CNS, while CD4⁺FOXP3⁺ regulatory T cells decreased in spleen and lymph nodes, Th2 cells and natural killer (NK) cells decreased in CNS. Additionally, the populations of microglia/macrophages and CD11C⁺CD11B⁺ dendritic cells (DCs) increased in CNS of IL-33 knockout mice with EAE, among which iNOS-producing microglia/macrophages increased. Moreover, resident astrocytes/microglia were more activated in IL-33 knockout mice with EAE. In vitro, after blocking the IL-33, the proliferation of primary astrocytes, the production of MCP-1/CCL2 and TNF-α by astrocytes, and the production of TNF-α by primary microglia stimulated by the homogenate of the peak stage of EAE were increased. Our results indicate that IL-33 plays a protective role in EAE and exerts extensive influences on multiple immune cells and neural cells involved in EAE.

Mechanisms of action of intravenous immunoglobulin

Taking advantage of the "World Apheresis Association/Société Française d'Hémaphérèse" meeting held in Paris in April 2016, this article reviews the current knowledge on the mechanisms of action of intravenous immunoglobulins. Immunoglobulins are a plasma-derived drug, which have been initially used as a replacement therapy for patients with antibody deficiency. Since 1980 they have also been used for their anti-inflammatory and immunomodulating efficacy in auto-immune diseases. Herein, we review the requirements for their production and composition before giving a specific attention to their mechanisms of action including substitution and immunomodulation.

Induction of Regulatory T Cells by Intravenous Immunoglobulin: A Bridge between Adaptive and Innate Immunity

Intravenous immunoglobulin (IVIg) is a polyclonal immunoglobulin G preparation with potent immunomodulatory properties. The mode of action of IVIg has been investigated in multiple disease states, with various mechanisms described to account for its benefits. Recent data indicate that IVIg increases both the number and the suppressive capacity of regulatory T cells, a subpopulation of T cells that are essential for immune homeostasis. IVIg alters dendritic cell function, cytokine and chemokine networks, and T lymphocytes, leading to development of regulatory T cells. The ability of IVIg to influence Treg induction has been shown both in animal models and in human diseases. In this review, we discuss data on the potential mechanisms contributing to the interaction between IVIg and the regulatory T-cell compartment.

Potentiation of cytokine-induced proliferation of human Natural Killer cells by intravenous immunoglobulin G

Intravenous IgG (IVIG) therapy can be used for immunomodulation. IL-2 is an immunoregulatory cytokine. We evaluated IVIG modulation of human blood lymphocyte response to IL-2 and other cytokines. Neither IVIG nor low concentrations of IL-2 (3-30U/ml) induced lymphocyte proliferation, but in combination they synergistically enhanced proliferation of NK cells. The CD56(bright) cells expanded more than CD56(dim) NK cells, with 90% of NK cells dividing up to 8 generations by day 6, while <8% of T cells divided. IVIG also potentiated NK cell proliferation with IL-12, IL-15 and IL-18. The IVIG+cytokine-expanded NK cells were less cytotoxic for K562 cells, than NK cells with cytokine alone. IVIG also enhanced interferon-γ production with IL-2, IL-12 and IL-18. In conclusion, IVIG selectively potentiates NK cell proliferation and interferon-γ secretion with IL-2, IL-12, IL-15 and IL-18 in vitro. These findings warrant evaluation in vivo in relation to NK cells and the immunoregulatory actions of IVIG.

Role of Natural Killer Cells in Intravenous Immunoglobulin-Induced Graft-versus-Host Disease Inhibition in NOD/LtSz-scidIL2rg(-/-) (NSG) Mice

Although clinical studies have yet to demonstrate clearly the use of intravenous immunoglobulin (IVIG) for prevention of graft-versus-host disease (GVHD), their effective use in a xenogeneic mouse model has been demonstrated. We aimed to determine the mechanism of action by which IVIG contributes to GVHD prevention in a xenogeneic mouse model. NOD/LtSz-scidIL2rg(-/-) (NSG) mice were used for our xenogeneic mouse model of GVHD. Sublethally irradiated NSG mice were injected with human peripheral blood mononuclear cells (huPBMCs) and treated weekly with PBS or 50 mg IVIG. Incidence of GVHD and survival were noted, along with analysis of cell subsets proliferation in the peripheral blood. Weekly IVIG treatment resulted in a robust and consistent proliferation of human natural killer cells that were activated, as demonstrated by their cytotoxicity against K562 target cells. IVIG treatment did not inhibit GVHD when huPBMCs were depleted in natural killer (NK) cells, strongly suggesting that this NK cell expansion was required for the IVIG-mediated prevention of GVHD in our mouse model. Moreover, inhibition of T cell activation by either cyclosporine A (CsA) or monoclonal antihuman CD3 antibodies abolished the IVIG-induced NK cell expansion. In conclusion, IVIG treatment induces NK cell proliferation, which is essential for IVIG-mediated protection of GVHD in our mouse model. Furthermore, activated T cells are mandatory for effective IVIG-induced NK cell proliferation. These results shed light on a new mechanism of action of IVIG and could explain why the efficacy of IVIG in preventing GVHD in a clinical setting, where patients receive CsA, has never been undoubtedly demonstrated.

The contribution of immune and glial cell types in experimental autoimmune encephalomyelitis and multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system characterised by widespread areas of focal demyelination. Its aetiology and pathogenesis remain unclear despite substantial insights gained through studies of animal models, most notably experimental autoimmune encephalomyelitis (EAE). MS is widely believed to be immune-mediated and pathologically attributable to myelin-specific autoreactive CD4+ T cells. In recent years, MS research has expanded beyond its focus on CD4+ T cells to recognise the contributions of multiple immune and glial cell types to the development, progression, and amelioration of the disease. This review summarises evidence of T and B lymphocyte, natural killer cell, macrophage/microglial, astrocytic, and oligodendroglial involvement in both EAE and MS and the intercommunication and influence of each cell subset in the inflammatory process. Despite important advances in the understanding of the involvement of these cell types in MS, many questions still remain regarding the various subsets within each cell population and their exact contribution to different stages of the disease.

Intravenous immunoglobulin G modulates peripheral blood Th17 and Foxp3(+) regulatory T cells in pregnant women with recurrent pregnancy loss

PROBLEM

Th17 cells and Foxp3(+) regulatory T (Treg) cells have been proposed as new risk factors for recurrent pregnancy loss (RPL). Intravenous immunoglobulin G (IVIG) was reported to modulate various immune cells. In this study, we investigated the effect of IVIG on the levels of Th17 and Treg cells and pregnancy outcome in women with RPL.

METHOD OF STUDY

Thirty-seven pregnant women with RPL were enrolled in this study. All had cellular immune abnormality in preconceptional evaluation. Blood was drawn on the day of IVIG treatment and 1 week later from the study subjects during early pregnancy. The proportions of IL-17(+) and Foxp3(+) T cells were analyzed using flow cytometry.

RESULTS

Study population was divided into four groups (Q1-Q4) based on ascending order of the levels of Th17 and Foxp3(+) T cells. IVIG down-regulated Th17 cells in the highest quartile, Q4 (P = 0.001), and up-regulated CD4(+)  Foxp3(+) T cells in Q1 and Q2 (P = 0.025 and 0.029, respectively). In addition, Th17/CD4(+)  Foxp3(+) T cell ratio decreased in Q4 (P = 0.040). We also found a positive trend between successful pregnancy outcome and CD8(+)  IL-17(+) T cells before IVIG treatment (P = 0.05).

CONCLUSION

Intravenous immunoglobulin G treatment modulated imbalance of Th17 and Foxp3(+) Treg cells in pregnant RPL women with cellular immune abnormality.

Therapeutic potential of atorvastatin-modified dendritic cells in experimental autoimmune neuritis by decreased Th1/Th17 cytokines and up-regulated T regulatory cells and NKR-P1(+) cells

Statins have pleiotropic effects which include anti-inflammatory and immunomodulatory effects. In the present study, dendritic cells treated with atorvastatin (statin-DCs) could be induced into tolerogenic DCs. Administration of these tolerogenic DCs ameliorated clinical symptoms in experimental autoimmune neuritis (EAN), which was associated with reduced number of inflammatory cells in sciatic nerves, inhibited CD4(+) T cells proliferation, down-regulated expression of co-stimulatory molecules (CD80 and CD86) and MHC class II, decreased levels of IFN-γ, TNF-α and IL-17A, increased number of NKR-P1(+) cells (including NK and NKT cells), up-regulated number of Treg cells in lymph node MNC as well as increased Foxp3 expression in the thymus. These data indicated that statin-DCs could develop as a new therapeutic strategy to GBS in the future.