The role of natural killer cells in autoimmune blistering diseases

The dysregulation of circulating innate lymphoid cells is related to autoantibodies in pemphigus vulgaris

BACKGROUND

Pemphigus vulgaris (PV) is a typical autoimmune disease caused by autoantibodies. Innate lymphoid cells (ILCs) are non-antigen-dependent populations composed of different subsets, also known as "mirror cells" of T cells, which play a crucial role in immune inflammatory diseases. However, the characteristics of ILCs in PV are unclear.

METHODS

Patients diagnosed with PV along with healthy controls in Second Xiangya Hospital of Central South University were studied. Flow cytometry was used to detect the proportion of ILC subsets in the peripheral blood. Anti-desmoglein (DSG) 1 and anti-DSG3 antibody levels of PV patients were detected.

RESULTS

Thirty-eight PV patients and 37 healthy controls were enrolled. There were no differences in sex or age between the two groups. Compared with controls, ILCs/CD45⁺ lymphocytes were significantly decreased in patients with PV. The frequency of ILC1s increased in patients with PV and was positively correlated with anti-DSG3 antibodies. However, the frequency of ILC3s decreased in patients with PV and was negatively correlated with anti-DSG1 antibodies. After methylprednisolone treatment, ILC1/ILC levels significantly decreased.

CONCLUSIONS

Circulating ILC subsets are associated with PV pathogenesis. Upregulated ILC1s seem to correlate positively with PV severity and can be restored after treatment.

Efficacy of Ustekinumab in Crohn's Disease With and Without Concurrent Autoimmune Skin Disease

BACKGROUND

Approximately 33% of Crohn's disease (CD) patients have associated autoimmune skin disease. The pathophysiology of the latter frequently involves interleukin-12/interleukin-23 signaling pathways that may also impact gut inflammation. Ustekinumab is an anti-IL-12/23 FDA-approved biologic for psoriasis and inflammatory bowel disease. However, its relative efficacy has never been studied in CD with autoimmune skin disease (CD-ASD) vs CD without autoimmune skin disease (CD-none).

METHODS

This is a retrospective, single-center, case-control study comparing markers of disease activity between CD-ASD and CD-none. Biomarkers (fecal calprotectin [FCP], C-reactive protein [CRP]) prior to drug initiation and after at least 5 months of standard IBD dose ustekinumab therapy were extracted from the medical record. In addition, 2 blinded observers performed 5-point Likert scoring before and after endoscopic, pathologic, and imaging reports.

RESULTS

In all, 395 CD patients received ustekinumab therapy (79 CD-ASD, 316 CD-none). Patients were similar in age; gender; ethnicity; CD severity, phenotype, and duration; tobacco, immunomodulator, and steroid use. Ustekinumab had greater efficacy in CD-ASD when evaluated by FCP (P = .0337) and CRP (P = .078). The CD-ASD group also showed better outcomes in Likert scores of endoscopy (P = .016), histopathology (P = .074), and imaging (P = .094). In all Likert parameters, CD-ASD had more patients with complete resolution of moderate/severe disease (P < .05). Additional subanalyses for surgeries, ulcers, abscesses, fistulas, and colitis were conducted, with colitis reaching statistical significance (P = .0011).

CONCLUSIONS

Concurrent autoimmune skin disease in CD is associated with greater ustekinumab effectiveness in controlling intestinal inflammation.

Single-Cell Transcriptome Profiling Unravels Distinct Peripheral Blood Immune Cell Signatures of RRMS and MOG Antibody-Associated Disease

Relapsing-remitting multiple sclerosis (RRMS) and myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) are inflammatory demyelinating diseases of the central nervous system (CNS). Due to the shared clinical manifestations, detection of disease-specific serum antibody of the two diseases is currently considered as the gold standard for the diagnosis; however, the serum antibody levels are unpredictable during different stages of the two diseases. Herein, peripheral blood single-cell transcriptome was used to unveil distinct immune cell signatures of the two diseases, with the aim to provide predictive discrimination. Single-cell RNA sequencing (scRNA-seq) was conducted on the peripheral blood from three subjects, i.e., one patient with RRMS, one patient with MOGAD, and one patient with healthy control. The results showed that the CD19+ CXCR4+ naive B cell subsets were significantly expanded in both RRMS and MOGAD, which was verified by flow cytometry. More importantly, RRMS single-cell transcriptomic was characterized by increased naive CD8+ T cells and cytotoxic memory-like Natural Killer (NK) cells, together with decreased inflammatory monocytes, whereas MOGAD exhibited increased inflammatory monocytes and cytotoxic CD8 effector T cells, coupled with decreased plasma cells and memory B cells. Collectively, our findings indicate that the two diseases exhibit distinct immune cell signatures, which allows for highly predictive discrimination of the two diseases and paves a novel avenue for diagnosis and therapy of neuroinflammatory diseases.

Association Between Severity of Leptospirosis and Subsequent Major Autoimmune Diseases: A Nationwide Observational Cohort Study

Introduction

Infections play a role in autoimmune diseases (AD). Leptospirosis has been linked to the trigger of systemic lupus erythematosus.

Objective

To investigate subsequent risk of major AD in hospitalized Taiwanese for Leptospirosis.

Methods

Retrospective observational cohort study was employed. The enrolled period was from 2000 to 2012. In the main model, we extracted 4026 inpatients with leptospirosis from the Taiwan National Health Insurance Research Database (NHIRD) and 16,104 participants without leptospirosis at a 1:4 ratio propensity-score matched (PSM) by age, gender, index year, and comorbidities. The follow-up period was defined as the time from the initial diagnosis of leptospirosis to major AD occurrence or 2013. This study was re-analyzed by frequency-matching as a sensitivity analysis for cross-validation. Univariable and multivariable Cox proportional hazards regression models were applied to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

Results

The adjusted HR (95% CI) of major ADs for the leptospirosis group was 4.45 (3.25–6.79) (p < 0.001) compared to the controls after full adjustment. The risk of major ADs was 5.52-fold (95% CI, 3.82–7.99) higher in leptospirosis patients hospitalized for seven days and above than the controls, while 2.80-fold (95% CI, 1.68–5.61) in those hospitalized less than seven days. The sensitivity analysis yields consistent findings. Stratified analysis revealed that the association between leptospirosis and major ADs was generalized in both genders, and all age groups.

Conclusions

Symptomatic leptospirosis is associated with increased rate of subsequent major ADs, and the risk seems to be higher in severe cases.

Reinforcing involvement of NK cells in psoriasiform dermatitis animal model

Psoriasis (Ps) is a chronic inflammatory immune-mediated disease with skin and joint manifestations, characterized by abnormal and rapid proliferation of keratinocytes and infiltration of psoriatic lesions with immune cells. Extensive literature suggests that Ps is a T-cell mediated disease its pathogenesis being highly related to innate and adaptative immune cells. Although natural killer (NK) cells are involved in the inflammatory process of Ps through pro-inflammatory cytokine secretion (tumor necrosis factor α, interferon γ), their role in this pathology is not yet fully elucidated. In order to study the involvement of NK subpopulations in the pathogenesis of Ps we used the imiquimod-based mouse model of psoriasiform dermatitis and NK cells complex phenotype patterns from peripheral blood (PB) and spleen were investigated. Skin inflammation and the disease severity were assessed using in vivo measurements (erythema, desquamation and induration parameters, PASI modified score), splenomegaly assessment and histopathological evaluation. Phenotypic characterization of NK cells in imiquimod (IMQ)-treated mice was performed by flow cytometry, for both PB and spleen cell suspension. A large panel of surface markers was used: maturation and activation markers [cluster of differentiation (CD)49b, CD11b, CD43, CD27, KLRG1, CD335, CD69, CD28, gp49R, CD45R, CD11c] and markers for cytokine receptors (CD25, CD122, CD132). Our experimental data showed important differences in IMQ-treated mouse NK cell phenotype as compared to control group. The maturation markers (CD11b, CD43, CD27, KLRG1) were found increased on NK cells, in periphery and spleen, while CD49b⁺NK1.1⁺ was significantly lower, and the alterations correlated with the severity of the disease. Our findings reflect the immune engagement toward activatory profile of NK cells and draw attention to evaluating Ps intensity correlated with the mature profile of circulating NK cells.

Oral administration of a non-absorbable plant cell-expressed recombinant anti-TNF fusion protein induces immunomodulatory effects and alleviates nonalcoholic steatohepatitis

AIM

To evaluate the immunomodulatory effect of oral administration of PRX-106 in the high-fat diet model.

METHODS

For 22 wk, C57BL/6 HFD-fed mice received daily oral treatments with BY-2 cells expressing recombinant anti-tumor necrosis factor alpha fusion protein (PRX-106). Mice were followed for serum liver enzyme and triglyceride levels, liver histology and intrahepatic and systemic FACS.

RESULTS

The orally administered non-absorbable PRX-106 was biologically active. Altered distribution of CD4+CD25+FoxP3+ between the liver and spleen and an increase in the intrasplenic-to-intrahepatic CD4+CD25+FoxP3+ ratio and a decrease in the intrasplenic-to-intrahepatic CD8+CD25+FoxP3+ ratio were observed. An increase in intrahepatic NKT cells and a decrease in the intrasplenic-to-intrahepatic NKT ratio were noted. Assessment of the CD4-to-CD8 ratios showed sequestration of CD8+ lymphocytes in the liver. These effects were associated with a decrease in serum triglyceride levels, decrease in the aspartate aminotransferase levels, serum glucose levels, and HOMA-IR score. A decrease in hepatic triglycerides content was observed in the high dose-treated mice.

CONCLUSION

Orally administered PRX-106 shows biological activity and exerts an immunomodulatory effect, alleviating liver damage. The data suggest that PRX-106 may provide an oral immunotherapy for nonalcoholic steatohepatitis.

NK Cell Subtypes as Regulators of Autoimmune Liver Disease

As major components of innate immunity, NK cells not only exert cell-mediated cytotoxicity to destroy tumors or infected cells, but also act to regulate the functions of other cells in the immune system by secreting cytokines and chemokines. Thus, NK cells provide surveillance in the early defense against viruses, intracellular bacteria, and cancer cells. However, the effecter function of NK cells must be exquisitely controlled to prevent inadvertent attack against normal “self” cells. In an organ such as the liver, where the distinction between immunotolerance and immune defense against routinely processed pathogens is critical, the plethora of NK cells has a unique role in the maintenance of homeostasis. Once self-tolerance is broken, autoimmune liver disease resulted. NK cells act as a “two-edged weapon” and even play opposite roles with both regulatory and inducer activities in the hepatic environment. That is, NK cells act not only to produce inflammatory cytokines and chemokines, but also to alter the proliferation and activation of associated lymphocytes. However, the precise regulatory mechanisms at work in autoimmune liver diseases remain to be identified. In this review, we focus on recent research with NK cells and their potential role in the development of autoimmune liver disease.

Natural killer cells from psoriasis vulgaris patients have reduced levels of cytotoxicity associated degranulation and cytokine production

Psoriasis vulgaris is a chronic inflammatory disease of the skin with a strong genetic component and immune system involvement. Although some evidence suggests that Natural Killer (NK) cells may play a part in psoriasis, their role is relatively unstudied and results are controversial. In this current study, NK cells from psoriasis patients exhibited reduced degranulation and produced lower levels of the pro-inflammatory cytokines IFN-γ and TNF-α. Further investigation found that NK cells from psoriasis patients and healthy controls expressed similar levels of activation markers, NK cell receptors and apoptosis-inducing molecules. In addition, comparable levels of several cytokines important in NK cell biology were found in the serum of psoriasis patients and healthy controls. Genotyping analysis revealed that HLA-C2, which provides a ligand for killer-cell immunoglobulin-like receptors (KIR) expressed by NK cells, was strongly associated with psoriasis susceptibility. However, no link between the KIR genes themselves and disease was found.

Effect of pharmacological intervention on MIP-1α, MIP-1β and MCP-1 expression in patients with psoriasis vulgaris

OBJECTIVE

To detect the expression level of macrophage inflammatory protein-1 (MIP-1)α, MIP-1β and monocyte chemoattractant protein-1 (MCP-1) in with psoriasis vulgaris and explore the role in the pathogenesis of psoriasis vulgaris.

METHODS

The level of MIP-1α, MIP-1β and MCP-1 in peripheral blood from 50 patients with psoriasis vulgaris and 50 normal controls were measured by enzyme linked immunosorbent assay. The correlation with psoriasis area and severity index (PASI) was analyzed. The level of MIP-1α, MIP-1β and MCP-1 was compared between psoriasis vulgaris patients at active stage and resting stage. And the change in MIP-1α, MIP-1β and MCP-1 before and after therapy was also observed.

RESULTS

The content of MIP-1α, MIP-1β and MCP-1 in patients with psoriasis vulgaris was (1342.78 ± 210.30), (175.28 ± 28.18) and (266.86 ± 32.75) ng/L, respectively, significantly higher than those in control group (P<0.05). The expression level of MIP-1α, MIP-1β and MCP-1 in peripheral blood of patients with psoriasis vulgaris was positively correlated with PASI (P<0.01). After acitretin therapy, expression level of MIP-1α, MIP-1β and MCP-1 in peripheral blood of patients with psoriasis vulgaris was significantly decreased.

CONCLUSIONS

Chemokine factor MIP-1α, MIP-1β and MCP-1 may be involved in the pathogenesis of psoriasis vulgaris.

Autoimmunity in 2012

The initiation and perpetuation of autoimmunity recognize numerous checkpoints, from the genomic susceptibility to the breakdown of tolerance. This latter phenomenon includes the loss of B cell anergy and T regulatory cell failure, as well as the production of autoantibodies and autoreactive T cells. These mechanisms ultimately lead to tissue injury via different mechanisms that span from the production of proinflammatory cytokines to the chemotaxis of immune cells to the target sites. The pathways to autoimmunity have been widely investigated over the past year and resulted in a number of articles in peer-reviewed journals that has increased by nearly 10 % compared to 2011. We herein follow on the attempt to provide a brief discussion of the majority of articles on autoimmune diseases that were published in the major immunology journals in the previous solar year. The selection is necessarily arbitrary and may thus not be seen as comprehensive but reflects current research trends. Indeed, 2012 articles were mostly dedicated to define new and old mechanisms with potential therapeutic implications in autoimmunity in general, though based on specific clinical conditions or animal models. As paradigmatic examples, the environmental influence on autoimmunity, Th17 changes modulating the autoimmune response, serum autoantibodies and B cell changes as biomarkers and therapeutic targets were major issues addressed by experimental articles in 2012. Further, a growing number of studies investigated the sex bias of autoimmunity and supported different working hypotheses to explain the female predominance, including sex chromosome changes and reproductive life factors. In conclusion, the resulting scenario illustrates that common factors may underlie different autoimmune diseases and this is well represented by the observed alterations in interferon-α and TGFβ or by the shared signaling pathways.

NK cell autoreactivity and autoimmune diseases

Increasing evidences have pointed out the relevance of natural killer (NK) cells in organ-specific and systemic autoimmune diseases. NK cells bear a plethora of activating and inhibiting receptors that can play a role in regulating reactivity with autologous cells. The activating receptors recognize natural ligands up-regulated on virus-infected or stressed or neoplastic cells. Of note, several autoimmune diseases are thought to be linked to viral infections as one of the first event in inducing autoimmunity. Also, it is conceivable that autoimmunity can be triggered when a dysregulation of innate immunity occurs, activating T and B lymphocytes to react with self-components. This would imply that NK cells can play a regulatory role during adaptive immunity; indeed, innate lymphoid cells (ILCs), comprising the classical CD56⁺ NK cells, have a role in maintaining or alternating tissue homeostasis secreting protective and/or pro-inflammatory cytokines. In addition, NK cells display activating receptors involved in natural cytotoxicity and the activating isoforms of receptors for HLA class I that can interact with healthy host cells and induce damage without any evidence of viral infection or neoplastic-induced alteration. In this context, the interrelationship among ILC, extracellular-matrix components, and mesenchymal stromal cells can be considered a key point for the control of homeostasis. Herein, we summarize evidences for a role of NK cells in autoimmune diseases and will give a point of view of the interplay between NK cells and self-cells in triggering autoimmunity.

Bi(o)communications among peripheral blood fractions: a focus on NK and NKT cell biology in rheumatoid arthritis

Rheumatoid Arthritis (RA) is an autoimmune disease with unknown pathophysiology involving many interwoven signalling cascades. ROS, NK and NKT cells might be crucial in the disease severity of RA of which the role of NK and NKT cells are controversial in literature. However, the role of oxidative stress, its impact on NK and NKT cell immunobiology and disease activity (DAS28) is largely unknown. Therefore, we studied the role of oxidative stress and NK cell subsets in the pathogenesis of RA. The state of oxidative stress in various peripheral blood fractions, percentage NK and NKT cell expression, their altered apoptotic signaling pathways involving mitochondrial membrane potential, FAS associated death domain (FADD) mediated pathways and DNA damage were analyzed. Results indicated a state of profound oxidative stress in the peripheral blood of RA patients where percentage of NK and NKT cell subsets diminished while ROS levels increased. The depolarized mitochondrial membrane potential, FAS, FASL and active caspase-3 positive NK and NKT cell subsets were considerably elevated in patients. The DNA damage, assessed as percentage of DNA in comet tail, was significantly elevated. Findings of the present work indicate increased apoptosis of peripheral NK and NKT cells in the diseased condition. PBMC and RBC are the major sites of enhanced oxidative stress. The state of oxidative stress and altered immunobiology of NK and NKT cells strongly correlated with Disease activity score. The present study strongly supports the protective role of NK cell subsets in the pathogenesis of RA.

Growth factors in synaptic function

Synapses are increasingly recognized as key structures that malfunction in disorders like schizophrenia, mental retardation, and neurodegenerative diseases. The importance and complexity of the synapse has fuelled research into the molecular mechanisms underlying synaptogenesis, synaptic transmission, and plasticity. In this regard, neurotrophic factors such as netrin, Wnt, transforming growth factor-β (TGF-β), tumor necrosis factor-α (TNF-α), and others have gained prominence for their ability to regulate synaptic function. Several of these factors were first implicated in neuroprotection, neuronal growth, and axon guidance. However, their roles in synaptic development and function have become increasingly clear, and the downstream signaling pathways employed by these factors have begun to be elucidated. In this review, we will address the role of these factors and their downstream effectors in synaptic function in vivo and in cultured neurons.

The role of p38 MAPK in the aetiopathogenesis of psoriasis and psoriatic arthritis

The pathogenetic mechanisms responsible for the induction of immune-mediated disorders, such as psoriasis, remain not well characterized. Molecular signaling pathways are not well described in psoriasis, as well as psoriatic arthritis, which is seen in up to 40% of patients with psoriasis. Signaling pathway defects have long been hypothesized to participate in the pathology of psoriasis, yet their implication in the altered psoriatic gene expression still remains unclear. Emerging data suggest a potential pathogenic role for mitogen activated protein kinases p38 (p38 MAPK) extracellular signal-regulated kinase 1/2 (ERK1/2), and c-Jun N-terminal kinase (JNK) in the development of psoriasis. The data are still limited, though, for psoriatic arthritis. This review discusses the current data suggesting a crucial role for p38 MAPK in the pathogenesis of these disorders.

p38 MAPK Signaling in Pemphigus: Implications for Skin Autoimmunity

p38 mitogen activated protein kinase (p38 MAPK) signaling plays a major role in the modulation of immune-mediated inflammatory responses and therefore has been linked with several autoimmune diseases. The extent of the involvement of p38 MAPK in the pathogenesis of autoimmune blistering diseases has started to emerge, but whether it pays a critical role is a matter of debate. The activity of p38 MAPK has been studied in great detail during the loss of keratinocyte cell-cell adhesions and the development of pemphigus vulgaris (PV) and pemphigus foliaceus (PF). These diseases are characterised by autoantibodies targeting desmogleins (Dsg). Whether autoantibody-antigen interactions can trigger signaling pathways (such as p38 MAPK) that are tightly linked to the secretion of inflammatory mediators which may perpetuate inflammation and tissue damage in pemphigus remains unclear. Yet, the ability of p38 MAPK inhibitors to block activation of the proapoptotic proteinase caspase-3 suggests that the induction of apoptosis may be a consequence of p38 MAPK activation during acantholysis in PV. This review discusses the current evidence for the role of p38 MAPK in the pathogenesis of pemphigus. We will also present data relating to the targeting of these cascades as a means of therapeutic intervention.

Regulatory NK cells in autoimmune disease

As major components of innate immunity, NK cells not only exert cell-mediated cytotoxicity against tumor cells or infected cells, but also act to regulate the function of other immune cells by secretion of cytokines and chemokines, thus providing surveillance in early defense against viruses, intracellular bacteria and cancer cells. However, the effector function of NK cells must be exquisitely controlled in order to prevent inadvertent attack against self normal cells. The activity of NK cells is defined by integration of signals coming from inhibitory and activation receptors. Inhibitory receptors not only distinguish healthy from diseased cells by recognize self-MHC class I molecules on cell surfaces with "missing-self" model, but also provide an educational signal that generates functional NK cells. NK cells enrich in immunotolerance organ and recent findings of different regulatory NK cell subsets have indicated the unique role of NK cells in maintenance of homeostasis. Once the self-tolerance is broken, autoimmune response may occur. Although data has demonstrated that NK cells play important role in autoimmune disorders, NK cells seemed to act as a two edged weapon and play opposite roles with both regulatory and inducer activity even in the same disease. The precise role and regulatory mechanisms need to be further determined. In this review, we focus on recent research on the association of NK cells and antoimmune diseases, particularly the genetic correlation, the immune tolerance and misrecognition of NK cells, the regulatory function of NK cells, and their potential role in autoimmunity.