Assessment of intracellular cytokines and regulatory cells in patients with autoimmune diseases and primary immunodeficiencies - novel tool for diagnostics and patient follow-up

Metalloproteins structural and functional insights into immunological patterns

Metalloproteins play a crucial role in regulating different aspects of the immune system in humans. They have various functions in immunity, including recognizing and presenting antigens, aiding in the movement and effectiveness of immune cells, and facilitating interactions between the host and pathogens. Understanding how these proteins work can help us develop new methods to control the immune response in different diseases. Metalloproteins contain metal ions in their structure, which allows them to perform these diverse functions. They encompass a wide range of enzymes, signaling molecules, and structural proteins that utilize metal ions as cofactors for their activities. Examples of metalloproteins include superoxide dismutase, catalase, and metalloproteases, which regulate oxidative stress, inflammation, and tissue remodelling processes associated with immune activation. By studying their functions and the effects of their dysfunction, researchers can develop strategies to improve immune function and combat various diseases. This review explores the diverse functions of metalloproteins in immune processes, highlighting their significance in both health and disease.

Antibodies in Aseptic Meningitis of Connective Tissue Disorder: A Case Report

Mixed connective tissue disorder (MCTD) is the first overlap syndrome described with features of overlapping manifestations of at least two other autoimmune rheumatic conditions. It is an autoimmune disease of rarity and is strongly associated with specific antibodies to U1 small nuclear ribonucleoprotein (anti-U1-RNP). This disorder affects almost all organs of the body, and it has varied clinical presentations as it has an autoimmune and inflammatory background, causing heightened immune cell activation. They present more commonly with less fatal symptoms like joint pain, stiffness, and mucocutaneous changes. The majority present initially with Raynaud's phenomenon followed by muscular skeletal involvement and around half of them present with swallowing problems due to esophageal dysmotility. Rarely do they also present with more morbid symptoms of pulmonary hypertension and central nervous system involvement. MCTD on follow-up had a 10 percent association with neurological manifestations as reported by the National Organization for Rare Diseases (NORD), and the most reported diseases were trigeminal neuralgia and aseptic meningitis. Patients presenting with such symptoms and, when treated only with guideline-based antibiotics therapy, would delay the treatment, leading to a poorer prognosis. The following is an interesting case of a young female presenting with a headache, which was masquerading as an underlying undiagnosed connective tissue disorder. Headache is a predominant presentation that has several etiologies in autoimmune disease and meticulous differential diagnosis workup is a must. This case highlights the fact that any persistent atypical, unusual symptom needs to be always considered for further evaluation to arrive at a diagnosis and for a favorable outcome.

Blood and CSF findings of cellular immunity in anti-NMDAR encephalitis

OBJECTIVES

To investigate the immunopathogenic mechanisms of anti-N-methyl-D-aspartate receptor encephalitis (NMDAR-E) by characterizing the changes of immune cells in both peripheral blood (PB) and cerebrospinal fluid (CSF) of patients with NMDAR-E.

METHODS

Cytology and flow cytometry were used to explore and compare different immunological parameters in PB and CSF of patients with NMDAR-E, viral encephalitis (VE) and healthy volunteers. Moreover, different models were established to assess the possibility of identifying NMDAR-E patients based on PB and CSF parameters.

RESULTS

The neutrophil counts and monocyte-to-lymphocyte ratios (MLR) in PB are higher in NMDAR-E patients than in both VEs and controls (P < 0.001, respectively), while the percentages of CD3 + T, CD4 + T lymphocytes, and the leukocytes count in CSF were lower in NMDAR-Es than in VEs (P < 0.01, respectively). The higher percentages of CD8 + T cells in blood and CSF were both correlated with more severe NMDAR-E (P < 0.05, respectively). The poor neurological status group had significantly higher PB leukocytes but lower CSF leukocyte count (P < 0.05). Longitudinal observations in patients with NMDAR-E showed a decreasing trend of leukocyte count, neutrophils count, neutrophil-to-monocyte ratios (NMR), and neutrophil-to-lymphocyte ratios (NLR) with the gradual recovery of neurological function.

CONCLUSIONS

The expression patterns of T lymphocyte subsets were different in patients with NMDAR-E and viral encephalitis. The changing trends of leukocyte and lymphocyte populations in peripheral blood and cerebrospinal fluid may provide clues for the diagnosis of different types of encephalitides, including NMDARE, and can be used as immunological markers to assess and predict the prognosis.

Hearing restoration and the stria vascularis: evidence for the role of the immune system in hearing restoration

PURPOSE OF REVIEW

This article reviews the current literature regarding the pathogenesis of immune-mediated sensorineural hearing loss, utilizes previously published single-nucleus transcriptional profiles to characterize cytokine and cytokine receptor expression in the adult stria vascularis cell types to support immune system interaction with the stria vascularis and reviews the current literature on immunomodulatory agents currently being used for hearing-restoration treatment.

RECENT FINDINGS

The literature review highlights recent studies that elucidate many cytokines and immune markers, which have been linked to various immune-mediated disease processes that have been observed with sensorineural hearing loss within the stria vascularis and highlights recent publications studying therapeutic targets for these pathways.

SUMMARY

This review highlights the current literature regarding the pathogenesis of immune-mediated hearing loss. The role of cochlear structures in human temporal bones from patients with immune-mediated sensorineural hearing loss are highlighted, and we review cytokine signalling pathways relevant to immune-mediated sensorineural hearing loss and localize genes encoding both cytokine and cytokine receptors involved in these pathways. Finally, we review immunomodulatory therapeutics in light of these findings and point to opportunities for the application of novel therapeutics by targeting these signalling pathways.

Patients with Common Variable Immunodeficiency Complicated by Autoimmune Phenomena Have Lymphopenia and Reduced Treg, Th17, and NK Cells

Most patients with primary immune deficiency suffer from recurrent infections; however, paradoxical autoimmune phenomena can also manifest. The aim of this study was to identify immunological markers of autoimmune phenomena associated with common variable immunodeficiency (CVID). The study included 33 adults with CVID divided into two groups: (1) those with noninfectious autoimmune complications (CVID-C (n = 24)) and (2) those with only infectious symptoms (CVID-OI (n = 9)). Flow cytometry of peripheral blood was performed and compared with systemic lupus erythematosus (SLE) patients (n = 17) and healthy controls (n = 20). We found that all lymphocytes were lower in CVID-C and SLE. NK cells were lowest in CVID-C. Th17 cells were significantly reduced in CVID-C and SLE. Tregs were significantly lower in CVID-C and SLE. Bregs did not significantly differ between any groups. Class-switched memory B cells were significantly lower in CVID-C and CVID-OI. Lastly, plasmablasts were significantly higher in SLE. Among the T cell subsets, CVID-C patients had lower naive and recent thymic emigrant CD4+ T cells. In conclusion, reduced Treg, Th17, and NK cells are features of CVID with autoimmune complications, and class-switched memory B cells can help distinguish patients with different causes of autoimmunity. Future studies are needed to confirm whether reductions of Treg, Th17, and NK cells might be a biomarker of more complicated CVID cases.

Single-Cell RNA Sequencing Reveals the Expansion of Cytotoxic CD4+ T Lymphocytes and a Landscape of Immune Cells in Primary Sjögren's Syndrome

Objective

Primary Sjögren’s syndrome (pSS) is a systemic autoimmune disease, and its pathogenetic mechanism is far from being understood. In this study, we aimed to explore the cellular and molecular mechanisms that lead to pathogenesis of this disease.

Methods

We applied single-cell RNA sequencing (scRNA-seq) to 57,288 peripheral blood mononuclear cells (PBMCs) from five patients with pSS and five healthy controls. The immune cell subsets and susceptibility genes involved in the pathogenesis of pSS were analyzed. Flow cytometry was preformed to verify the result of scRNA-seq.

Results

We identified two subpopulations significantly expand in pSS patients. The one highly expressing cytotoxicity genes is named as CD4⁺ CTLs cytotoxic T lymphocyte, and another highly expressing T cell receptor (TCR) variable gene is named as CD4⁺ TRAV13-2+ T cell. Flow cytometry results showed the percentages of CD4⁺ CTLs, which were profiled with CD4⁺ and GZMB⁺ staining; the total T cells of 10 patients with pSS were significantly higher than those of 10 healthy controls (P= 0.008). The expression level of IL-1β in macrophages, TCL1A in B cells, as well as interferon (IFN) response genes in most cell subsets was upregulated in the patients with pSS. Susceptibility genes including HLA-DRB5, CTLA4, and AQP3 were highly expressed in patients with pSS.

Conclusions

Our data revealed disease-specific immune cell subsets and provided some potential new targets of pSS. Specific expansion of CD4⁺ CTLs may be involved in the pathogenesis of pSS, which might give valuable insights for therapeutic interventions of pSS.

The Gut Microbiota and Its Relevance to Peripheral Lymphocyte Subpopulations and Cytokines in Patients with Rheumatoid Arthritis

Growing experimental and clinical evidence suggests that a chronic inflammatory response induced by gut microbiome critically contribute to the development of rheumatoid arthritis (RA). Previous studies demonstrated the disturbance of lymphocyte subpopulations in RA patients. The purpose of this study was to explore the characteristics of gut microbiome and the associations between bacterium and lymphocyte subpopulations as well as cytokines in patients with RA. Fecal samples from 205 RA patients and 199 healthy controls (HCs) were collected for bacterial DNA extraction and 16S ribosomal RNA (rRNA) gene sequencing. The levels of peripheral lymphocyte subpopulation such as T, B, CD4⁺T, CD8⁺T, NK, T helper 1 (Th1), Th2, Th17, and regulatory T cells (Tregs) of these subjects were detected by flow cytometry combined with standard absolute counting beads. The serum levels of cytokines interleukin-2 (IL-2), IL-4, IL-6, IL-10, IL-17, tumour necrosis factor-α (TNF-α), and interferon-γ (INF-γ) were tested by flow cytometric bead array (CBA). Alpha and beta diversity of gut microbiome were explored by bioinformatics analysis. Spearman rank correlation test was used to explore the relationships between gut microbiome and lymphocyte subsets as well as serum cytokines. The diversity and relative abundance of intestinal microbiota in patients with RA were significantly different from those in HCs. Detailly, the abundant of phylum Proteobacteria in RA patients was more than that in HCs, while Firmicutes was less than in HCs. There was increased relative abundance of genus Clostridium_XlVa as well as genus Blautia, more abundance of Ruminococcus2 in patients with lower levels of T, B, CD4⁺T, and Tregs. In addition, the relative abundances of Pelagibacterium, Oxalobacter, ClostridiumXlVb, and ClostridiumXVIII were correlated with cytokines. Gut microbiome of RA patients was clearly different from that of HCs. Abnormal bacteria communities are associated with the altered levels of lymphocyte subpopulation and cytokines, which might be one of the pathogenesis of RA.

Functionally specialized human CD4+ T-cell subsets express physicochemically distinct TCRs

The organizational integrity of the adaptive immune system is determined by functionally discrete subsets of CD4⁺ T cells, but it has remained unclear to what extent lineage choice is influenced by clonotypically expressed T-cell receptors (TCRs). To address this issue, we used a high-throughput approach to profile the αβ TCR repertoires of human naive and effector/memory CD4⁺ T-cell subsets, irrespective of antigen specificity. Highly conserved physicochemical and recombinatorial features were encoded on a subset-specific basis in the effector/memory compartment. Clonal tracking further identified forbidden and permitted transition pathways, mapping effector/memory subsets related by interconversion or ontogeny. Public sequences were largely confined to particular effector/memory subsets, including regulatory T cells (Tregs), which also displayed hardwired repertoire features in the naive compartment. Accordingly, these cumulative repertoire portraits establish a link between clonotype fate decisions in the complex world of CD4⁺ T cells and the intrinsic properties of somatically rearranged TCRs.

Variability of ex-vivo stimulated T-cells secretory profile in healthy subjects

Peripheral blood lymphocytes (PBL) are able to synthesize various cytokines that play key roles in the immune response and intercellular signaling. Since alterations in cytokine production and/or activity occur in many pathological processes, the study of cytokine synthetic capacity of PBL is a valuable tool for assessing the immune profile. In this paper, we aimed to investigate the variability of interleukin-2 (IL-2), tumor necrosis factor-alpha (TNF-α) and interferon gamma (IFN-γ) synthetic capacity of CD4+/CD8+ T-cells stimulated ex-vivo in healthy subjects, by means of a commercial intracellular cytokine staining (ICS) protocol. Peripheral blood mononuclear cells were isolated from 16 healthy subjects by Ficoll gradient centrifugation and activated ex-vivo with PMA/Ionomycin/Brefeldin-A for 4 hours. Activated PBL were surface-stained for CD3/CD4/CD8, fixed and permeabilized. ICS was performed using anti-human IL-2/TNF-α/IFN-γ and samples were analyzed on a BD-FACSAria-III flow cytometer. We recorded high post-isolation and post-activation mean viabilities: 82.1% and 82.4% respectively, p=0.84. Both CD4+/CD8+ subpopulations were found to partially produce each of the three cytokines, but in different proportions. On average, a significantly greater percentage of CD4+ cells was shown to produce IL-2 and TNF-α, compared with CD8+ cells (61.5%+/-5.8 vs. 25%+/-5.6 and 26.9%+/-11 vs. 7.5%+/-3.3 respectively, p---lt---0.0001 for both). Contrarily, IFN-γ was produced by a higher proportion of CD8+ cells (8.4%+/-3.9 vs. 6.8%+/-3.2, p=0.01). These results show that the employed ICS protocol elicits a satisfactory and consistent cytokine response from PBL of healthy subjects. The collected data may be used to outline a preliminary reference range for future studies on both healthy/pathological subjects.

Blockade of miR-142-3p promotes anti-apoptotic and suppressive function by inducing KDM6A-mediated H3K27me3 demethylation in induced regulatory T cells

In vitro induced human regulatory T cells (iTregs) have in vivo therapeutic utility. MicroRNAs (miRNAs) are a family of approximately 22-nucleotide non-coding RNAs that are processed from longer precursors by the RNases Drosha and Dicer. miRNAs regulate post-transcriptional protein expression through messenger RNA destabilization or translational silencing; miR-142-3p regulates natural Treg function through autophagy. We hypothesized that this miRNA may also have an iTreg regulation function. Antagomir-mediated knockdown of miR-142-3p improved Foxp3 (forkhead box P3) expression, regulatory function, cytokine expression, and apoptosis of iTregs in vitro, with or without inflammatory cytokine stimulation. miR-142-3p knockdown increased autophagy-related protein 16-1-mediated autophagy. Target prediction and luciferase assay results indicated that miR-142-3p binds directly to lysine demethylase 6A (KDM6A), which resulted in demethylation of H3K27me3 and in turn upregulated expression of the anti-apoptotic protein Bcl-2. Based on these results, we propose a novel strategy that uses knockdown of miR-142-3p to enhance anti-apoptotic ability and function of iTregs by increasing KDM6A and Bcl-2 expression. This approach might be used as a treatment to control established chronic immune-mediated autoimmune and inflammatory diseases.

Necroptosis in stressed ovary

Stress is deeply rooted in the modern society due to limited resources and large competition to achieve the desired goal. Women are more frequently exposed to several stressors during their reproductive age that trigger generation of reactive oxygen species (ROS). Accumulation of ROS in the body causes oxidative stress (OS) and adversely affects ovarian functions. The increased OS triggers various cell death pathways in the ovary. Beside apoptosis and autophagy, OS trigger necroptosis in granulosa cell as well as in follicular oocyte. The OS could activate receptor interacting protein kinase-1(RIPK1), receptor interacting protein kinase-3 (RIPK3) and mixed lineage kinase domain-like protein (MLKL) to trigger necroptosis in mammalian ovary. The granulosa cell necroptosis may deprive follicular oocyte from nutrients, growth factors and survival factors. Under these conditions, oocyte becomes more susceptible towards OS-mediated necroptosis in the follicular oocytes. Induction of necroptosis in encircling granulosa cell and oocyte may lead to follicular atresia. Indeed, follicular atresia is one of the major events responsible for the elimination of majority of germ cells from cohort of ovary. Thus, the inhibition of necroptosis could prevent precautious germ cell depletion from ovary that may cause reproductive senescence and early menopause in several mammalian species including human.

The presence of anti-nuclear antibodies alone is associated with changes in B cell activation and T follicular helper cells similar to those in systemic autoimmune rheumatic disease

BACKGROUND

Diagnosis of systemic autoimmune rheumatic diseases (SARD) relies on the presence of hallmark anti-nuclear antibodies (ANA), many of which can be detected years before clinical manifestations. However, ANAs are also seen in healthy individuals, most of whom will not develop SARD. Here, we examined a unique cohort of asymptomatic ANA⁺ individuals to determine whether they share any of the cellular immunologic features seen in SARD.

METHODS

Healthy ANA^- controls and ANA⁺ (ANA ≥1:160 by immunofluorescence) participants with no SARD criteria, with at least one criterion (undifferentiated connective tissue disease (UCTD)), or meeting SARD classification criteria were recruited. Peripheral blood cellular immunological changes were assessed by flow cytometry and transcript levels of BAFF, interferon (IFN)-induced and plasma cell-expressed genes were quantified by NanoString.

RESULTS

A number of the immunologic abnormalities seen in SARD, including changes in peripheral B (switched memory) and T (iNKT, T regulatory, activated memory T follicular helper) subsets and B cell activation, were also seen in asymptomatic ANA⁺ subjects and those with UCTD. The extent of these immunologic changes correlated with ANA titer or the number of different specific ANAs produced. Principal component analysis of the cellular data indicated that a significant proportion of asymptomatic ANA⁺ subjects and subjects with UCTD clustered  with patients with early SARD, rather than ANA^- healthy controls.

CONCLUSIONS

ANA production is associated with altered T and B cell activation even in asymptomatic individuals. Some of the currently accepted cellular features of SARD may be associated with ANA production rather than the immunologic events that cause symptoms in SARD.

Immunoregulatory Effects of Myeloid-Derived Suppressor Cell Exosomes in Mouse Model of Autoimmune Alopecia Areata

The treatment of autoimmune diseases still poses a major challenge, frequently relying on non-specific immunosuppressive drugs. Current efforts aim at reestablishing self tolerance using immune cells with suppressive activity like the regulatory T cells (Treg) or the myeloid-derived suppressor cells (MDSC). We have demonstrated therapeutic efficacy of MDSC in mouse Alopecia Areata (AA). In the same AA model, we now asked whether MDSC exosomes (MDSC-Exo) can replace MDSC. MDSC-Exo from bone marrow cells (BMC) cultures of healthy donors could substantially facilitate treatment. With knowledge on MDSC-Exo being limited, their suitability needs to be verified in advance. Protein marker profiles suggest comparability of BMC- to ex vivo collected inflammatory MDSC/MDSC-Exo in mice with a chronic contact dermatitis, which is a therapeutic option in AA. Proteome analyses substantiated a large overlap of function-relevant molecules in MDSC and MDSC-Exo. Furthermore, MDSC-Exo are taken up by T cells, macrophages, NK, and most avidly by Treg and MDSC-Exo uptake exceeds binding of MDSC themselves. In AA mice, MDSC-Exo preferentially target skin-draining lymph nodes and cells in the vicinity of remnant hair follicles. MDSC-Exo uptake is accompanied by a strong increase in Treg, reduced T helper proliferation, mitigated cytotoxic activity, and a slight increase in lymphocyte apoptosis. Repeated MDSC-Exo application in florid AA prevented progression and sufficed for partial hair regrowth. Deep sequencing of lymphocyte mRNA from these mice revealed a significant increase in immunoregulatory mRNA, including FoxP3 and arginase 1. Downregulated mRNA was preferentially engaged in prohibiting T cell hyperreactivity. Taken together, proteome analysis provided important insights into potential MDSC-Exo activities, these Exo preferentially homing into AA-affected organs. Most importantly, changes in leukocyte mRNA seen after treatment of AA mice with MDSC-Exo sustainably supports the strong impact on the adaptive and the non-adaptive immune system, with Treg expansion being a dominant feature. Thus, MDSC-Exo could potentially serve as therapeutic agents in treating AA and other autoimmune diseases.

Janus-Faced Myeloid-Derived Suppressor Cell Exosomes for the Good and the Bad in Cancer and Autoimmune Disease

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells originally described to hamper immune responses in chronic infections. Meanwhile, they are known to be a major obstacle in cancer immunotherapy. On the other hand, MDSC can interfere with allogeneic transplant rejection and may dampen autoreactive T cell activity. Whether MDSC-Exosomes (Exo) can cope with the dangerous and potentially therapeutic activities of MDSC is not yet fully explored. After introducing MDSC and Exo, it will be discussed, whether a blockade of MDSC-Exo could foster the efficacy of immunotherapy in cancer and mitigate tumor progression supporting activities of MDSC. It also will be outlined, whether application of native or tailored MDSC-Exo might prohibit autoimmune disease progression. These considerations are based on the steadily increasing knowledge on Exo composition, their capacity to distribute throughout the organism combined with selectivity of targeting, and the ease to tailor Exo and includes open questions that answers will facilitate optimizing protocols for a MDSC-Exo blockade in cancer as well as for strengthening their therapeutic efficacy in autoimmune disease.

Intra-Articular Injection of Human Synovial Membrane-Derived Mesenchymal Stem Cells in Murine Collagen-Induced Arthritis: Assessment of Immunomodulatory Capacity In Vivo

The aim of this study was to evaluate the efficacy of human synovial membrane-derived MSCs (SM-MSCs) in murine collagen-induced arthritis (CIA). Male mice (age 7–9 weeks) were injected intra-articularly with SM-MSCs obtained from patients with osteoarthritis, on days 28, 32, and 38 after bovine type II collagen immunization. The efficacy of SM-MSCs in CIA was evaluated clinically and histologically. Cytokine profile analyses were performed by real-time polymerase chain reaction and multiplex analyses. Splenic helper T (Th) cell and regulatory B cell subsets were analyzed by flow cytometry. Intra-articular SM-MSC injection ameliorated the clinical and histological severity of arthritis. Decrease in tumor necrosis factor-α, interferon-γ, and interleukin- (IL-) 17A and increase in IL-10 production were observed after SM-MSC treatment. Flow cytometry showed that Th1 and Th17 cells decreased, whereas Th2, regulatory T (Treg), and PD-1⁺CXCR5⁺FoxP3⁺ follicular Treg cells increased in the spleens of SM-MSC-treated mice. Regulatory B cell analysis showed that CD21^hiCD23^hi transitional 2 cells, CD23^lowCD21^hi marginal zone cells, and CD19⁺CD5⁺CD1d⁺IL-10⁺ regulatory B cells increased following SM-MSC treatment. Our results demonstrated that SM-MSCs injected in inflamed joints in CIA had a therapeutic effect and could prevent arthritis development and suppress immune responses via immunoregulatory cell expansion.

A new benzenediamine derivative modulates Toll-like receptors-induced myeloid dendritic cells activation and ameliorates lupus-like syndrome in MRLlpr/lpr mice

Modulators of the over-activation of myeloid dendritic cells (mDCs) by Toll-like receptors (TLRs) have an advantage in the treatment of systemic lupus erythematosus (SLE). This study was designed to evaluate the effects of FC-99, a novel benzenediamine derivative, on TLR-induced activation of mDCs, and to assess the efficacy of FC-99 in a murine model of SLE. In vitro, FC-99 inhibited the phenotypic (CD40 and MHC-II) and functional activation (IL-12 and CXCL10) of mDCs induced by TLR ligands. In vivo, MRLlpr/lpr mice displayed renal diseases associated with increased levels of proteinuria and immunoglobulin, which were ameliorated by FC-99. Enhanced accumulation and activation of mDCs in lymphoid organs was also impaired by FC-99. Additionally, FC-99 inhibited the activation of IκB-α and upregulated the expression of TNFα-induced protein 3 (TNFAIP3) in vitro and in vivo. These results indicate that FC-99 modulates TLR-induced activation of mDCs and ameliorates lupus-like syndrome in MRLlpr/lpr mice. This effect is closely associated with the inhibition of IκB-α and upregulation of TNFAIP3.

NKG2D+CD4+ T Cells Kill Regulatory T Cells in a NKG2D-NKG2D Ligand- Dependent Manner in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) features a decreased pool of CD4⁺CD25⁺Foxp3⁺ T regulatory (Treg) cells. We had previously observed NKG2D⁺CD4⁺ T cell expansion in contrast to a decreased pool of Treg cells in SLE patients, but whether NKG2D⁺CD4⁺ T cells contribute to the decreased Treg cells remains unclear. In the present study, we found that the NKG2D⁺CD4⁺ T cells efficiently killed NKG2D ligand (NKG2DL)⁺ Treg cells in vitro, whereby the surviving Treg cells in SLE patients showed no detectable expression of NKG2DLs. It was further found that MRL/lpr lupus mice have significantly increased percentage of NKG2D⁺CD4⁺ T cells and obvious decreased percentage of Treg cells, as compared with wild-type mice. Adoptively transferred NKG2DL⁺ Treg cells were found to be efficiently killed in MRL/lpr lupus mice, with NKG2D neutralization remarkably attenuating this killing. Anti-NKG2D or anti-interferon-alpha receptor (IFNAR) antibodies treatment in MRL/lpr mice restored Treg cells numbers and markedly ameliorated the lupus disease. These results suggest that NKG2D⁺CD4⁺ T cells are involved in the pathogenesis of SLE by killing Treg cells in a NKG2D-NKG2DL-dependent manner. Targeting the NKG2D-NKG2DL interaction might be a potential therapeutic strategy by which Treg cells can be protected from cytolysis in SLE patients.

The Telomere/Telomerase System in Chronic Inflammatory Diseases. Cause or Effect?

Telomeres are specialized nucleoprotein structures located at the end of linear chromosomes and telomerase is the enzyme responsible for telomere elongation. Telomerase activity is a key component of many cancer cells responsible for rapid cell division but it has also been found by many laboratories around the world that telomere/telomerase biology is dysfunctional in many other chronic conditions as well. These conditions are characterized by chronic inflammation, a situation mostly overlooked by physicians regarding patient treatment. Among others, these conditions include diabetes, renal failure, chronic obstructive pulmonary disease, etc. Since researchers have in many cases identified the association between telomerase and inflammation but there are still many missing links regarding this correlation, the latest findings about this phenomenon will be discussed by reviewing the literature. Our focus will be describing telomere/telomerase status in chronic diseases under the prism of inflammation, reporting molecular findings where available and proposing possible future approaches.

Cytokine Milieu in Undifferentiated Connective Tissue Disease: a Comprehensive Review

Undifferentiated connective tissue disease (UCTD) is a unique clinical entity, a potential forerunner of well-established systemic autoimmune/rheumatic diseases. UCTD is characterized by the presence of various clinical symptoms, as well as a diverse repertoire of autoantibodies, resembling systemic autoimmune diseases. Since approximately one third of these patients consequently transform into a full-blown systemic autoimmune/rheumatic disease, it is of major importance to assess pathogenic factors leading to this progression. In view of the fact that the serological and clinical picture of UCTD and systemic autoimmune diseases are very similar, it is assumed that analogous pathogenic factors perpetuate both disease entities. In systemic autoimmune conditions, a quantitative and qualitative impairment of regulatory T cells has been shown previously, and in parallel, a relative dominance of pro-inflammatory Th17 cells has been introduced. Moreover, the imbalance between regulatory and Th17 cells plays a pivotal role in the initiation and propagation of UCTD. Additionally, we depict a cytokine imbalance, which give raise to a biased T cell homeostasis from the UCTD phase throughout the fully developed systemic autoimmune disease stage. The levels of interleukin (IL)-6, IL-12, IL-17, IL-23, and interferon (IFN)-γ were pathologically increased with a parallel reduction of IL-10. We believe that the assessment of Th17/Treg cell ratio, as well as the simultaneous quantitation of cytokines may give a useful diagnostic tool at the early UCTD stage to identify patients with a higher chance of consecutive disease progression toward serious systemic autoimmune diseases. Moreover, the early targeted immunomodulating therapy in these patients may decelerate, or even stop this progression, before the development of serious autoimmune conditions with organ damage.

Multiplexed femtomolar quantitation of human cytokines in a fluoropolymer microcapillary film

Sensitive quantitation of multiple cytokines can provide important diagnostic information during infection, inflammation and immunopathology. In this study sensitive immunoassay detection of human cytokines IL-1β, IL-6, IL-12p70 and TNFα is shown for singleplex and multiplex formats using a novel miniaturized ELISA platform. The platform uses a disposable plastic multi-syringe aspirator (MSA) integrating 8 disposable fluoropolymer microfluidic test strips, each containing an array of ten 200 μm mean i.d. microcapillaries coated with a set of monoclonal antibodies. Each MSA device thus performs 10 tests on 8 samples, delivering 80 measurements. Unprecedented levels of sensitivity were obtained with the novel fluoropolymer microfluidic material and simple colorimetric detection in a flatbed scanner. The limit of detection for singleplex detection ranged from 2.0 to 15.0 pg ml(-1), i.e. 35 and 713 femtomolar for singleplex cytokine detection, and the intra- and inter-assay coefficient of variation (CV) remained within 10%. In addition, a triplex immunoassay was developed for measuring IL-1β, IL-12p70 and TNFα simultaneously from a given sample in the pg ml(-1) range. These assays permit high sensitivity measurement with rapid <15 min assay or detection from undiluted blood serum. The portability, speed and low-cost of this system are highly suited to point-of-care testing and field diagnostics applications.

Intravenous immunoglobulins (IVIG) in systemic sclerosis: a challenging yet promising future

The etiology and pathogenesis of systemic sclerosis are still largely unknown, but a variety of humoral and cellular autoimmune phenomena have been documented. In addition, the rarity of the disease, the broad spectrum of clinical manifestations, and the relevant risk of severe complications as well as the highly variable disease course render its management a major challenge. Some immunomodulatory agents have been used, but no single agent has given a convincing proof of effectiveness, and treatment has remained largely symptomatic through recent years. Novel therapies are currently being tested and may have the potential of modifying the disease process and overall clinical outcome. Efficacy of intravenous immunoglobulins (IVIG) in different regimens (1-2 g/kg of body weight, administered over 2-5 consecutive days) has been described in a limited number of trials and small case series, showing benefits in skin, articular, and lung interstitial disease symptoms. However, studies on IVIG in systemic sclerosis still remain few, and further randomized controlled trials should be undertaken to assess their clinical effectiveness or define the optimal dosage and times of administration.

Autoimmunity in 2013

The peer-reviewed publications in the field of autoimmunity published in 2013 represented a significant proportion of immunology articles and grew since the previous year to indicate that more immune-mediated phenomena may recognize an autoimmune mechanism and illustrated by osteoarthritis and atherosclerosis. As a result, our understanding of the mechanisms of autoimmunity is becoming the paradigm for translational research in which the progress in disease pathogenesis for both tolerance breakdown and inflammation perpetuation is rapidly followed by new treatment approaches and clinical management changes. The similarities across the autoimmune disease spectrum outnumber differences, particularly when treatments are compared. Indeed, the therapeutics of autoimmune diseases are based on a growing armamentarium that currently includes monoclonal antibodies and small molecules which act by targeting molecular markers or intracellular mediators with high specificity. Among the over 100 conditions considered as autoimmune, the common grounds are well illustrated by the data reported for systemic lupus erythematosus and rheumatoid arthritis or by the plethora of studies on Th17 cells and biomarkers, particularly serum autoantibodies. Further, we are particularly intrigued by studies on the genomics, epigenetics, and microRNA at different stages of disease development or on the safe and effective use of abatacept acting on the costimulation of T and B cells in rheumatoid arthritis. We are convinced that the data published in 2013 represent a promising background for future developments that will exponentially impact the work of laboratory and clinical scientists over the next years.

Unique topics and issues in rheumatology and clinical immunology

Clinicians are facing unexpected issues in everyday practice, and these may become counterintuitive or challenging. Illustrative examples are provided by the hypersensitivity to universally used immunosuppressants such as corticosteroids or antibiotics such as beta-lactam. Secondly, additional issues are represented by the discovery of new pathogenetic mechanisms involved in rheumatoid and psoriatic arthritis or other chronic inflammatory diseases, genomic susceptibility to enigmatic diseases such as giant cell arteritis, or the shared role of specific mediators such as semaphorins. Third, the therapeutic armamentarium has dramatically changed over the past decade following the introduction of biotechnological drugs, and new mechanisms are being proposed to reduce adverse events or increase the drug effectiveness, particularly on cardiovascular comorbidities. Finally, rare diseases continue to represent difficult cases, as for Cogan's syndrome, with limited literature available for clinical recommendations. For these reason, the present issue of Clinical Reviews in Allergy and Immunology is timely and dedicated to these and other unique topics in clinical immunology and allergy. The aim of this issue is thus to help clinicians involved in internal medicine as well as allergists and clinical immunologists while discussing new pathways that will prove important in the near future.

U1-RNP and Toll-like receptors in the pathogenesis of mixed connective tissue diseasePart II. Endosomal TLRs and their biological significance in the pathogenesis of mixed connective tissue disease

Mixed connective tissue disease (MCTD) is a chronic autoimmune immunopathological disease of unknown etiology, which is characterized by the presence of various clinical symptoms and the presence of autoantibodies against U1-RNP particles. The U1-RNP component engages immune cells and their receptors in a complex network of interactions that ultimately lead to autoimmunity, inflammation, and tissue injury. The anti-U1-RNP autoantibodies form an immune complex with self-RNA, present in MCTD serum, which can act as endosomal Toll-like receptor (TLR) ligands. Inhibition of TLRs by nucleic acids is a promising area of research for the development of novel therapeutic strategies against pathogenic infection, tumorigenesis and autoimmunity. In this review we summarize current knowledge of endogenous TLRs and discuss their biological significance in the pathogenesis of MCTD. In part I we described the structure, biological function and significance of the U1-RNP complex in MCTD.

Selected Aspects in the Pathogenesis of Autoimmune Diseases

Autoimmune processes can be found in physiological circumstances. However, they are quenched with properly functioning regulatory mechanisms and do not evolve into full-blown autoimmune diseases. Once developed, autoimmune diseases are characterized by signature clinical features, accompanied by sustained cellular and/or humoral immunological abnormalities. Genetic, environmental, and hormonal defects, as well as a quantitative and qualitative impairment of immunoregulatory functions, have been shown in parallel to the relative dominance of proinflammatory Th17 cells in many of these diseases. In this review we focus on the derailed balance between regulatory and Th17 cells in the pathogenesis of autoimmune diseases. Additionally, we depict a cytokine imbalance, which gives rise to a biased T-cell homeostasis. The assessment of Th17/Treg-cell ratio and the simultaneous quantitation of cytokines, may give a useful diagnostic tool in autoimmune diseases. We also depict the multifaceted role of dendritic cells, serving as antigen presenting cells, contributing to the development of the pathognomonic cytokine signature and promote cellular and humoral autoimmune responses. Finally we describe the function and role of extracellular vesicles in particular autoimmune diseases. Targeting these key players of disease progression in patients with autoimmune diseases by immunomodulating therapy may be beneficial in future therapeutic strategies.

U1-RNP and TLR receptors in the pathogenesis of mixed connective tissue diseasePart I. The U1-RNP complex and its biological significance in the pathogenesis of mixed connective tissue disease

Mixed connective tissue disease (MCTD) is a rare autoimmune syndrome, signified by complex interactions between disease-related phenomena, including inflammation, proliferative vascular arteriopathy, thrombotic events and humoral autoimmune processes. It is still controversial whether MCTD is a distinct clinical entity among systemic connective tissue diseases, although several authors consider that it is distinct and underline characteristic, distinct clinical, serological and immunogenetic features. The putative target of autoimmunity in MCTD is U1-RNP, which is a complex of U1-RNA and small nuclear RNP. Both the U1-RNA component and the specific proteins, particularly U1-70K, engage immune cells and their receptors in a complex network of interactions that ultimately lead to autoimmunity, inflammation, and tissue injury. U1-RNA is capable of inducing manifestations consistent with TLR activation. Stimulation of innate immunity by native RNA molecules with a double-stranded secondary structure may help explain the high prevalence of autoimmunity to RNA binding proteins.

Humoral autoimmunity: a failure of regulatory T cells?

Regulatory T cells (Tregs) are essential in maintaining tolerance to self. Several lines of evidence indicate that Tregs are functionally impaired in a variety of autoimmune diseases, leading to inefficient regulation of autoimmune T cells. Recent findings also suggest that Tregs are essential in controlling autoreactive B cells. The recently identified follicular regulatory T cell subset (TFR) is thought to regulate the production of autoantibodies in the germinal center (GC) response. Here we provide an update on the role of Tregs in controlling the GC response, and whether defective control over B cell tolerance contributes to autoimmunity.

Parasite load induces progressive spleen architecture breakage and impairs cytokine mRNA expression in Leishmania infantum-naturally infected dogs

Canine Visceral Leishmaniasis (CVL) shares many aspects with the human disease and dogs are considered the main urban reservoir of L. infantum in zoonotic VL. Infected dogs develop progressive disease with a large clinical spectrum. A complex balance between the parasite and the genetic/immunological background of the host are decisive for infection evolution and clinical outcome. This study comprised 92 Leishmania infected mongrel dogs of various ages from Mato Grosso, Brazil. Spleen samples were collected for determining parasite load, humoral response, cytokine mRNA expression and histopathology alterations. By real-time PCR for the ssrRNA Leishmania gene, two groups were defined; a low (lowP, n = 46) and a high parasite load groups (highP, n = 42). When comparing these groups, results show variable individual humoral immune response with higher specific IgG production in infected animals but with a notable difference in CVL rapid test optical densities (DPP) between highP and lowP groups. Splenic architecture disruption was characterized by disorganization of white pulp, more evident in animals with high parasitism. All cytokine transcripts in spleen were less expressed in highP than lowP groups with a large heterogeneous variation in response. Individual correlation analysis between cytokine expression and parasite load revealed a negative correlation for both pro-inflammatory cytokines: IFNγ, IL-12, IL-6; and anti-inflammatory cytokines: IL-10 and TGFβ. TNF showed the best negative correlation (r² = 0.231; p<0.001). Herein we describe impairment on mRNA cytokine expression in leishmania infected dogs with high parasite load associated with a structural modification in the splenic lymphoid micro-architecture. We also discuss the possible mechanism responsible for the uncontrolled parasite growth and clinical outcome.

Overexpression of Toll-like receptor 8 correlates with the progression of podocyte injury in murine autoimmune glomerulonephritis

Members of the Toll-like receptor (TLR) family serve as pathogen sensors and participate in local autoimmune responses. This study found a correlation between glomerular injury and TLR expression by analysing BXSB/MpJ-Yaa (BXSB-Yaa) lupus model mice. In isolated glomeruli, the mRNA expression of several TLRs was higher in BXSB-Yaa mice than in healthy control BXSB mice. In particular, the expression of Tlr8 and its downstream cytokines was markedly increased. In mouse kidneys, TLR8 protein and mRNA localized to podocytes, and TLR8 protein expression in the glomerulus was higher in BXSB-Yaa mice than in BXSB mice. In BXSB-Yaa mice, the glomerular levels of Tlr8 mRNA negatively correlated with the glomerular levels of podocyte functional markers (Nphs1, Nphs2, and Synpo) and positively correlated with urinary albumin levels. Furthermore, the glomerular and serum levels of miR-21, a putative microRNA ligand of TLR8, were higher in BXSB-Yaa mice than in BXSB mice. The urinary levels of Tlr8 mRNA were also higher in BXSB-Yaa mice than in BXSB mice. In conclusion, the overexpression of TLR8 correlates with the progression of podocyte injury in glomerulonephritis. Thus, altered levels of urinary Tlr8 mRNA might reflect podocyte injury.

Regulatory T-cells in autoimmune diseases: challenges, controversies and--yet--unanswered questions

Regulatory T cells (Tregs) are central to the maintenance of self-tolerance and tissue homeostasis. Markers commonly used to define human Tregs in the research setting include high expression of CD25, FOXP3 positivity and low expression/negativity for CD127. Many other markers have been proposed, but none unequivocally identifies bona fide Tregs. Tregs are equipped with an array of mechanisms of suppression, including the modulation of antigen presenting cell maturation and function, the killing of target cells, the disruption of metabolic pathways and the production of anti-inflammatory cytokines. Treg impairment has been reported in a number of human autoimmune conditions and includes Treg numerical and functional defects and conversion into effector cells in response to inflammation. In addition to intrinsic Treg impairment, resistance of effector T cells to Treg control has been described. Discrepancies in the literature are common, reflecting differences in the choice of study participants and the technical challenges associated with investigating this cell population. Studies differ in terms of the methodology used to define and isolate putative regulatory cells and to assess their suppressive function. In this review we outline studies describing Treg frequency and suppressive function in systemic and organ specific autoimmune diseases, with a specific focus on the challenges faced when investigating Tregs in these conditions.

Preclinical systemic lupus erythematosus

Preclinical lupus encompasses a spectrum from enhanced SLE risk without clinical symptoms to individuals with autoantibodies and some SLE clinical features without meeting ACR classification. Studies have identified antibody and serological biomarkers years before disease onset. Incomplete lupus and undifferentiated connective tissue disease may occur during preclinical disease periods, but only 10-20% of these individuals transition to SLE and many have a mild disease course. Further studies are warranted to characterize biomarkers of early disease, identify individuals in need of close monitoring or preventive interventions, and elucidate mechanisms of disease pathogenesis without confounding factors of immunosuppressive medications or organ damage.

Th17 cells in inflammation and autoimmunity

T helper 17 (Th17), a distinct subset of CD4(+) T cells with IL-17 as their major cytokine, orchestrate the pathogenesis of inflammatory and autoimmune diseases. Dysregulated Th17 cells contribute to inflammatory and autoimmune diseases. Candidate biologics are in development for targeting IL-17, IL-17 receptors or IL-17 pathways. Several drugs that impact the IL-17 pathway are already in clinical trials for the treatment of autoimmune diseases. In this review we provide evidence for the role of Th17 cells in immune-mediated diseases. An understanding of the role of Th17 in these conditions will provide important insights and unravel novel targets for therapeutic intervention.

IgA deficiency and autoimmunity

IgA is the most abundant immunoglobulin in the human body, and performs a very specialized role which involves mucosal immunity, development of tolerance and protection against infection. IgA is the key immunoglobulin in the respiratory and gastrointestinal tracts, which provide the most intimate interface between the environment and self. Normal levels of IgA are based on early studies consisting of only small numbers of patients. The international consensus definition of IgA deficiency is a level of 0.07g/l after the age of four years in the absence of IgG and IgM deficiencies. The epidemiology of IgA deficiency reveals interesting variances between geographical regions - the incidence in Caucasians being much higher than that in Asians. IgA deficiency has also been found to co-exist with autoimmune diseases, allergies and malignancies. The association with autoimmunity is particularly interesting because it suggests a common genetic linkage that could potentially also explain the diversity in geoepidemiology. Both MHC and non-MHC associations have been described and the 8.1 haplotype has been significantly associated with autoimmunity in IgA deficiency patients over controls. Non-MHC genetic associations include IFIH1 and CLEC16A. The mutations leading to IgA deficiency have not been defined, but in some cases of IgA deficiency it has been suggested that the pathogenesis involves a failure in switched memory B cells that can lead to this cohort experiencing an increased incidence of recurrent bacterial infections or autoimmune diseases. Attempts to investigate the role of cytokines that can induce IgA synthesis in cells of patients with IgA deficiency, such as IL21 or the combination of CD40L/anti-CD40, IL-4 and IL10, are underway.