The role of interleukin-6 signalling and its therapeutic blockage in skewing the T cell balance in rheumatoid arthritis

Serum IL-6 level trajectory for predicting the effectiveness and safety of tocilizumab in the treatment of refractory Takayasu arteritis

AIM

To explore the value of serial monitoring of serum interleukin-6 (IL-6) levels for predicting treatment response and occurrence of adverse events during tocilizumab (TCZ) treatment in refractory Takayasu arteritis (TAK).

METHODS

TAK patients receiving TCZ treatment were prospectively recruited and followed up at 1 month, 3 months and then every 3-6 months. Serum IL-6 levels were measured at each visit. Overall response was the combination of complete and partial response, requiring resolution of signs and symptoms, hsCRP and ESR level decreased at least by half, no progression on imaging and dose of glucocorticoid <15 mg/d.

RESULTS

Thirty-five patients with a median follow up duration of 17 [9-44] months were included. The change of IL-6 after TCZ treatment for 6 months compared to the baseline was significantly lower in patients achieved overall response at 6, 12, 18 and 24 months. The ratio of IL-6 at 6 months to baseline could predict overall response at 12 and 24 months after TCZ treatment. With a cutoff value of 1.6, the sensitivity and specificity were 83.3 % and 87.5 % for 12 months, while 100 % and 88.9 % for 24 months. Patients with the ratio less than 1.6 were also 9 times more likely to achieve sustained improvement without treatment intensification. No correlation between IL-6 dynamics and occurrence of adverse events was found.

CONCLUSIONS

The change of IL-6 levels after TCZ treatment for 6 months compared to the baseline can predict the overall treatment response at 12 months, 24 months and sustained improvement.

Treg plasticity and human diseases

INTRODUCTION

As a subset of CD4+ T cells, regulatory T cells (Tregs) with the characteristic expression of transcription factor FOXP3 play a key role in maintaining self-tolerance and regulating immune responses. However, in some inflammatory circumstances, Tregs can express cytokines of other T help (Th) cells by internal reprogramming, which is called Treg plasticity. These reprogrammed Tregs with impaired suppressive ability contribute to the progression of diseases by secreting pro-inflammatory cytokines. However, in the tumor microenvironment (TME), such changes in phenotype rarely occur in Tregs, on the contrary, Tregs usually display a stronger suppressive function and inhibit anti-tumor immunity. It is important to understand the mechanisms of Treg plasticity in inflammatory diseases and cancers.

OBJECTIVES

In this review, we summarize the characteristics of different Th-like Tregs and discuss the potential mechanisms of these changes in phenotype. Furthermore, we summarize the Treg plasticity in human diseases and discuss the effects of these changes in phenotype on disease progression, as well as the potential application of drugs or reagents that regulate Treg plasticity in human diseases.

CONCLUSIONS

Treg plasticity is associated with inflammatory diseases and cancers. Regulating Treg plasticity is a promising direction for the treatment of inflammatory diseases and cancers.

Triterpenes as Potential Drug Candidates for Rheumatoid Arthritis Treatment

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease characterized by joint inflammation, swelling and pain. Although RA mainly affects the joints, the disease can also have systemic implications. The presence of autoantibodies, such as anti-cyclic citrullinated peptide antibodies and rheumatoid factors, is a hallmark of the disease. RA is a significant cause of disability worldwide associated with advancing age, genetic predisposition, infectious agents, obesity and smoking, among other risk factors. Currently, RA treatment depends on anti-inflammatory and disease-modifying anti-rheumatic drugs intended to reduce joint inflammation and chronic pain, preventing or slowing down joint damage and disease progression. However, these drugs are associated with severe side effects upon long-term use, including immunosuppression and development of opportunistic infections. Natural products, namely triterpenes with anti-inflammatory properties, have shown relevant anti-arthritic activity in several animal models of RA without undesirable side effects. Therefore, this review covers the recent studies (2017-2022) on triterpenes as safe and promising drug candidates for the treatment of RA. These bioactive compounds were able to produce a reduction in several RA activity indices and immunological markers. Celastrol, betulinic acid, nimbolide and some ginsenosides stand out as the most relevant drug candidates for RA treatment.

Evidence of Disruption in Neural Regeneration in Dry Eye Secondary to Rheumatoid Arthritis

The purpose of our study was to analyze abnormal neural regeneration activity in the cornea through means of confocal microscopy in rheumatoid arthritis patients with concomitant dry eye disease. We examined 40 rheumatoid arthritis patients with variable severity and 44 volunteer age- and gender-matched healthy control subjects. We found that all examined parameters were significantly lower (p < 0.05) in rheumatoid arthritis patients as opposed to the control samples: namely, the number of fibers, the total length of the nerves, the number of branch points on the main fibers and the total nerve-fiber area. We examined further variables, such as age, sex and the duration of rheumatoid arthritis. Interestingly, we could not find a correlation between the above variables and abnormal neural structural changes in the cornea. We interpreted these findings via implementing our hypotheses. Correspondingly, one neuroimmunological link between dry eye and rheumatoid arthritis could be through the chronic Piezo2 channelopathy-induced K_2P-TASK1 signaling axis. This could accelerate neuroimmune-induced sensitization on the spinal level in this autoimmune disease, with Langerhans-cell activation in the cornea and theorized downregulated Piezo1 channels in these cells. Even more importantly, suggested principal primary-damage-associated corneal keratocyte activation could be accompanied by upregulation of Piezo1. Both activation processes on the periphery would skew the plasticity of the Th17/Treg ratio, resulting in Th17/Treg imbalance in dry eye, secondary to rheumatoid arthritis. Hence, chronic somatosensory-terminal Piezo2 channelopathy-induced impaired Piezo2-Piezo1 crosstalk could result in a mixed picture of disrupted functional regeneration but upregulated morphological regeneration activity of these somatosensory axons in the cornea, providing the demonstrated abnormal neural corneal morphology.

Tocilizumab attenuates acute lung injury in rats with sepsis by regulating S100A12/NLRP3

OBJECTIVE

To investigate the mechanism of Tocilizumab (TCZ) in attenuating acute lung injury in rats with sepsis by regulating the S100A12/NLRP3 axis.

METHODS

A rat model of sepsis was constructed using cecal ligation and puncture (CLP). Rats were treated with TCZ, and their lung tissue was collected. H&E staining was used to detect pathologic damage to lung tissue, and lung wet/dry (W/D) weight ratio was measured to assess pulmonary edema. Lipid oxidation assay and superoxide dismutase (SOD) activity assay kits were used to measure malondialdehyde (MDA) and SOD levels. Primary rat pulmonary microvascular endothelial cells (MPVECs) were treated with lipopolysaccharide (LPS) to construct a rat model of sepsis, which was then treated with TCZ. The mRNA and protein expressions of S100A12/NLRP3 were detected by qRT-PCR and western blot, respectively. S100A12 knockdown and overexpression plasmids, and NLRP3 knockdown plasmids were constructed and transfected into sepsis cells to intervene in the levels of S100A12/NLRP3. The apoptosis rate was detected by apoptosis assay. The levels of IL-6, TNF-α, and IL-10 in cells and tissues were analyzed by ELISA.

RESULTS

Compared to the Sham group, the CLP group had increased W/D weight ratio of lung tissue, IL-6, TNF-α, and MDA levels, lowered IL-10 and SOD levels, and more severe tissue damage (all P<0.05). After TCZ treatment, the above indicators were improved. The expressions of S100A12/NLRP3 cells were increased in LPS-induced MPVECs, but decreased after TCZ treatment. LPS induced apoptosis, but TCZ reduced the apoptosis, weakened the secretion levels of IL-6 and TNF-α, and enhanced IL-10 secretion levels. Transfection to cause the overexpression of S100A12 or NLRP3 plasmid partially counteracted the effect of TCZ. Knockdown of S100A12 was transfected on the basis of overexpression of NLRP3, which weakened the countervailing effect of overexpressed NLRP3 on TCZ.

CONCLUSION

TCZ has a therapeutic effect on lung injury in rats with sepsis by reducing the expressions of S100A12/NLRP3.

Features of Peripheral Blood Th-Cell Subset Composition and Serum Cytokine Level in Patients with Activity-Driven Ankylosing Spondylitis

Th cells may exhibit pathological activity depending on the regulatory and functional signals sensed under a wide range of immunopathological conditions, including ankylosing spondylitis (AS). The relationship between Th cells and cytokines is important for diagnoses and for determining treatment. Accordingly, the aim of this study was to investigate the relationship between Th-cell subset composition and serum cytokine profile for patients with activity-driven AS. In our study, patients were divided into two groups according to disease activity: low-activity AS (ASDAS-CRP < 2.1) and high-activity AS (ASDAS-CRP > 2.1). The peripheral blood Th cell subset composition was studied by flow cytometry. Using multiplex analysis, serum cytokine levels were quantified and investigated. It was found that only patients with high-activity AS had reduced central memory (CM) Th1 cells (p = 0.035) but elevated numbers of CM (p = 0.014) and effector memory (EM) Th2 cells (p < 0.001). However, no activity-driven change in the Th17 cell subset composition was observed in AS patients. Moreover, low-AS activity patients had increased numbers of Tfh17 EM cells (p < 0.001), whereas high-AS activity was associated with elevated Tfh2 EM level (p = 0.031). The serum cytokine profiles in AS patients demonstrated that cues stimulating cellular immunity were increased, but patients with high-AS activity reveled increased IL-5 level (p = 0.017). Analyzing the data obtained from AS patients allowed us to conclude that Th cell subset differentiation was mainly affected during the CM stage and characterized the IL-23/IL-17 regulatory axis, whereas increased humoral immunity was observed in the high-AS activity group.

Nanoparticles for Inducing Antigen-Specific T Cell Tolerance in Autoimmune Diseases

Autoimmune diseases affect many people worldwide. Current treatment modalities focus on the reduction of disease symptoms using anti-inflammatory drugs which can lead to side effects due to systemic immune suppression. Restoration of immune tolerance by down-regulating auto-reactive cells in an antigen-specific manner is currently the “holy grail” for the treatment of autoimmune diseases. A promising strategy is the use of nanoparticles that can deliver antigens to antigen-presenting cells which in turn can enhance antigen-specific regulatory T cells. In this review, we highlight some promising cell targets (e.g. liver sinusoidal endothelial cells and splenic marginal zone macrophages) for exploiting natural immune tolerance processes, and several strategies by which antigen-carrying nanoparticles can target these cells. We also discuss how nanoparticles carrying immunomodulators may be able to activate tolerance in other antigen-presenting cell types. Finally, we discuss some important aspects that must be taken into account when translating data from animal studies to patients.

Tetrandrine Ameliorates Rheumatoid Arthritis in Mice by Alleviating Neutrophil Activities

Rheumatoid arthritis (RA) is a common autoimmune disease worldwide. Neutrophils play critical roles in the onset and development of RA and are the promising target for RA treatment. Tetrandrine is a bis-benzyl isoquinoline alkaloid derived from the traditional Chinese herbal Stephania tetrandra S. Moore. Tetrandrine is effective in alleviating RA by inhibiting macrophage inflammatory response, fibroblast overproliferation, and pannus formation. However, whether tetrandrine regulates the activities of neutrophils in RA is largely unknown. In this study, we adopted adjuvant-induced arthritis (AA) murine model to explore the effect of tetrandrine on RA and neutrophils. Twenty-eight mice were divided into four groups. The control group was injected with PBS in the limbs and treated with PBS by intraperitoneal injection (i.p.) from Day 10 to Day 37. The arthritis murine model was induced by injecting FCA into the ankle joints of hind limbs. The AA group, the AA + TET group, and the AA + DEX group mice were treated with PBS, tetrandrine (6 mg/kg), or dexamethasone (1 mg/kg) i.p. daily, respectively. Arthritic scores were evaluated, and the joint diameter was measured every three days. A cytometric bead assay was performed to measure the concentrations of IFN-γ, TNF-α, and IL-6 in the serum. H&E staining and Safranin O-fast staining were adopted to monitor the tissue changes in the joint. Immunohistochemistry assays were applied to detect the MPO, NE, CitH3, and PAD4 expression levels. To assess the effect of tetrandrine on neutrophil activities in vitro, CCK8 tests were applied to determine cell viability. The qPCR and ELISA were performed to determine IL-1β and IL-6 expression levels. Immunofluorescence assays were performed to measure the formation of NETs. The results indicated that tetrandrine significantly alleviated the symptoms of RA in terms of the ankle diameter (from 4.629 ± 2.729 to 3.957 ± 0.257; P < 0.01) and ankle score (from 4.000 ± 0.000 to 3.286 ± 0.756; P < 0.05). Tetrandrine treatment significantly increased the cartilage areas and decreased serum IL-6 significantly (from 5.954 ± 2.127 to 2.882 ± 2.013; P < 0.01). The immunohistochemistry assays also showed decreased expression levels of NE, MPO, PAD4, and CitH3 induced by tetrandrine in comparison with the AA group (P < 0.01). The qPCR assays and ELISAs showed that tetrandrine had an anti-inflammatory effect in vitro by significantly inhibiting IL-6 (P < 0.01). The immunofluorescence assays showed that NET formation induced by PMA could be reduced by tetrandrine (P < 0.01). In conclusion, tetrandrine has good efficacy in treating RA by regulating neutrophil-involved inflammation and NET formation.

Downregulation of TIGIT Expression in FOXP3+Regulatory T Cells in Acute Coronary Syndrome

Objective

Little is currently known on the role of T-cell immunoglobulin and ITIM domain (TIGIT) expression in Foxp3+ regulatory T cells (TIGIT+Tregs) in acute coronary syndrome (ACS) patients. The aim of this study was to investigate the role and alterations of TIGIT+Tregs in ACS patients.

Methods

We enrolled 117 subjects, including 61 ACS patients, 26 chronic coronary syndrome (CCS) patients, and 30 control subjects without coronary artery disease. The quantification of TIGIT+Tregs was determined by flow cytometry; serum interleukin-6 (IL-6) and transforming growth factor-β (TGF-β) were also measured.

Results

TIGIT+Tregs expression was significantly lower in ACS patients compared with CCS and control patients (P<0.05). The expression of TIGIT+Tregs was comparable in patients with and without traditional risk factors (P>0.05). Logistic regression analysis revealed that TIGIT+Tregs levels are independent predictors of ACS (P<0.01). Receiver-operating characteristic (ROC) curve analysis showed the expression levels of TIGIT+Tregs had a discriminative power for ACS (P<0.01). IL-6 levels were increased (P<0.01), while TGF-β was decreased in ACS patients compared with CCS and control patients (P<0.01). Meanwhile, an inverse correlation between IL-6 and TIGIT+Tregs was observed (P<0.01), while a positive correlation between TGF-β and TIGIT+Tregs was found (P<0.05).

Conclusion

TIGIT+Tregs levels are significantly reduced in ACS, accompanied by upregulated IL-6 and downregulated TGF-β expression. The downregulated TIGIT+Tregs are independent predictors of ACS. These findings suggest that TIGIT+Tregs may have an anti-inflammatory and protective effect on ACS, and its decreased expression may be associated with atherosclerotic plaque destabilization.

Cytokine storm in tuberculosis and IL-6 involvement

Tuberculosis is probably the most seasoned illness of the humanity. Intricacies or subsequent death emerging from these infections are frequently connected with cytokine storm. Interleukin-6 (IL-6) plays a crucial role in the immune response to tuberculosis. Therefore, there is a need to research some new therapeutic approaches to block IL-6 signaling that are right now being applied to the M. tuberculosis. In this review, we investigate the implication of IL-6 in the context of tuberculosis research.

Interleukin-2 and regulatory T cells in rheumatic diseases

Failure of regulatory T (T_reg) cells to properly control immune responses leads invariably to autoimmunity and organ damage. Decreased numbers or impaired function of T_reg cells, especially in the context of inflammation, has been documented in many human autoimmune diseases. Restoration of T_reg cell fitness and/or expansion of their numbers using low-dose natural IL-2, the main cytokine driving T_reg cell survival and function, has demonstrated clinical efficacy in early clinical trials. Genetically modified IL-2 with an extended half-life and increased selectivity for T_reg cells is now in clinical development. Administration of IL-2 combined with therapies targeting other pathways involved in the expression of autoimmune diseases should further enhance its therapeutic potential. Ongoing clinical efforts that capitalize on the early clinical success of IL-2 treatment should bring the use of this cytokine to the forefront of biological treatments for autoimmune diseases.

Chronobiology and Chronotherapy in Inflammatory Joint Diseases

Circadian rhythm perturbations can impact the evolution of different conditions, including autoimmune diseases. This narrative review summarizes the current understanding of circadian biology in inflammatory joint diseases and discusses the potential application of chronotherapy. Proinflammatory cytokines are key players in the development and progression of rheumatoid arthritis (RA), regulating cell survival/apoptosis, differentiation, and proliferation. The production and secretion of inflammatory cytokines show a dependence on the human day–night cycle, resulting in changing cytokine plasma levels over 24 h. Moreover, beyond the circadian rhythm of cytokine secretion, disturbances in timekeeping mechanisms have been proposed in RA. Taking into consideration chronotherapy concepts, modified-release (MR) prednisone tablets have been introduced to counteract the negative effects of night-time peaks of proinflammatory cytokines. Low-dose MR prednisone seems to be able to improve the course of RA, reduce morning stiffness and morning serum levels of IL-6, and induce significant clinical benefits. Additionally, methotrexate (MTX) chronotherapy has been reported to be associated with a significant improvement in RA activity score. Similar effects have been described for polymyalgia rheumatica and gout, although the available literature is still limited. Growing knowledge of chronobiology applied to inflammatory joint diseases could stimulate the development of new drug strategies to treat patients in accordance with biological rhythms and minimize side effects.

Erosive arthritis in systemic lupus erythematosus: not only Rhupus

Systemic lupus erythematosus (SLE)-related arthritis has been traditionally defined as non-erosive and is therefore considered a minor manifestation requiring a mild treatment. However, the concept of non-erosive arthritis in SLE has been challenged with the advent of sensitive imaging techniques, such as high-resolution ultrasound with power Doppler or magnetic resonance. The application of these new imaging tools has demonstrated that up to 40% of SLE patients with joint involvement can develop erosive damage. Thus, this more aggressive phenotype can be identified not only in patients overlapping with rheumatoid arthritis (RA). This issue has been considered for the first time in the classification criteria proposed by Systemic Lupus International Collaborating Clinics in 2012, in which the old definition of "non-erosive arthritis" was replaced with either synovitis or tenderness in two or more joints with morning stiffness, suggesting the possible presence of an erosive phenotype. Accordingly, the 2019 EULAR/ACR's SLE recommendations advise treatment with immunosuppressant or biological drugs for patients with RA-like moderate arthritis. As a result, several studies have investigated the presence of biomarkers associated with SLE erosive damage. A relevant role seems to be played by the autoantibodies directed against post-translational modified proteins: above all, a significant association has been observed with antibodies directed against citrullinated and carbamylated proteins. Conversely, the rheumatoid factor was not associated with this more aggressive SLE-related arthritis. Nonetheless, some pro-inflammatory factors have been associated with erosive damage in SLE patients. These results suggest new pathogenic mechanisms underlining erosive arthritis, only partially shared with RA. Hence, in the present narrative review, we summarized available data about erosive arthritis in SLE patients, in the light of its impact on therapeutic decisions.

Downregulation of miR-98-5p expression induces interleukin-6 expression in rheumatoid fibroblast-like synoviocytes

AIM

The increased level of interleukin-6 (IL-6) plays a significant role in the pathogenesis of rheumatoid arthritis (RA). Specific blockade of IL-6 or its receptor has been used successfully in treating RA. MicroRNAs can regulate gene expression and act as regulators of target genes. Manipulation of specific microRNAs provides a novel therapeutic strategy for treating/preventing diseases. This study explored the role of miR-98-5p in the regulation of IL-6 expression in rheumatoid fibroblast-like synoviocytes (RA-FLSs).

METHODS

Real-time PCR was used to detect miR-98-5p expression in RA-FLSs and normal human fibroblast-like synovial cells (HFLSs). Site-directed gene mutagenesis and reporter gene assay were performed to identify the interaction between miR-98-5p and IL-6. Manipulation of miR-98-5p expression in RA-FLS used transfection with miR-98-5p mimic or inhibitor. Stimulation of FLSs with IL-1β induced IL-6 production. Enzyme-linked immunosorbent assay was used to detect the level of IL-6 secreted into the RA-FLS culture supernatant.

RESULTS

Compared with HFLSs, the expression of miR-98-5p in RA-FLSs was significantly downregulated, and was negatively correlated with DAS28 scores and rheumatoid factor. In patients with anti-keratin antibody-positive RA, the expression level of miR-98-5p was lower. miR-98-5p negatively regulated the expression of IL-6 in RA-FLSs. After IL-1β stimulation, the expression of miR-98-5p decreased and the level of IL-6 protein was upregulated during IL-6 secretion.

CONCLUSION

These data suggest that manipulation of miR-98-5p, which negatively modulates IL-6 expression, may be a potential clinical approach in RA.

Arthritis in systemic lupus erythematosus is characterized by local IL-17A and IL-6 expression in synovial fluid

Arthritis is a common clinical feature of systemic lupus erythematosus (SLE) and is usually non‐erosive, as opposed to rheumatoid arthritis (RA). While RA synovial pathology has been extensively studied, little is known about the pathophysiology of lupus arthritis. Here, we aimed to explore the cytokine and cellular compartments in synovial fluids of SLE patients with arthritic manifestations. Acellular synovial fluid and paired serum samples from SLE patients (n = 17) were analyzed with cytokine bead array for T helper‐associated cytokines. From two SLE patients, synovial fluid mononuclear cells (SFMC) could also be captured and were analyzed by multiparameter flow cytometry to dissect T cell, B cell, monocyte and dendritic cell phenotypes. SLE‐derived SFMC were further stimulated in vitro to measure their capacity for producing interferon (IFN)‐γ and interleukin (IL)‐17A. All patients fulfilled the ACR 1982 classification criteria for SLE. Clinical records were reviewed to exclude the presence of co‐morbidities such as osteoarthritis or overlap with RA. IL‐17A and IL‐6 levels were high in SLE synovial fluid. A clear subset of the synovial CD4⁺ T cells expressed CCR6⁺, a marker associated with T helper type 17 (Th17) cells. IL‐17A‐production was validated among CD4⁺CCR6⁺ T cells following in‐vitro stimulation. Furthermore, a strong IFN‐γ production was observed in both CD4⁺ and CD8⁺ cells. Our study shows high IL‐17A and IL‐6 levels in synovial fluids of patients with lupus arthritis. The Th17 pathway has been implicated in several aspects of SLE disease pathogenesis and our data also point to Th17 involvement for lupus arthritis.

Plasticity of Treg and imbalance of Treg/Th17 cells in patients with systemic sclerosis modified by FK506

To determine the effects of Tacrolimus (FK506) on Treg cells and subpopulations in SSc patients and assess the ability of FK506 to modify the immune imbalance of Treg/Th17 cells. We analyzed PBMC from five SSc patients and six healthy control by flow cytometry after cultured with 0, 0.1, 1, or 10 ng/ml FK506 in vitro. The number of Treg cells decreased in SSc patients treated with FK506. The number of FrI cells were decreased in SSc following FK506 treatment. The drug did increase the frequency of FrII/Treg cells, but not FrII cells. However, FK506 significantly decreased FrIII in both SSc patients and controls. FK506 clearly decreased the numbers of Th17 cells and FoxP3⁺IL-17⁺ cells. The proliferation capacity of cells was also inhibited by FK506, which had a greater effect on FoxP3^- cells than FoxP3⁺ cells. FK506 did inhibit the proliferation of FrIII cells, but not FrI or FrII cells. Our study provides that FK506 reduced the number of FoxP3^low CD45RA^- T cells (FrIII) by inhibiting its proliferation. Therefore, FK506 modifies Treg cells and the immune imbalance between Tregs and Th17 cells in SSc patients.

Effect of interleukin-6, -17, -21, -22, and -23 and STAT3 on signal transduction pathways and their inhibition in autoimmune arthritis

Rheumatic diseases are complex autoimmune diseases which include among others rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA), and psoriatic arthritis (PsA). These diseases are characterized by prolonged and increased secretion of inflammatory factors, eventually leading to inflammation. This is often accompanied by persistent pain and stiffness in the joint and finally bone destruction and osteoporosis. These diseases can occur at any age, regardless of gender or origin. Autoimmune arthritis is admittedly associated with long-term treatment, and discontinuation of medication is associated with unavoidable relapse. Therefore, it is important to detect the disease at an early stage and apply appropriate preventative measures. During inflammation, pro-inflammatory factors such as interleukins (IL)-6, -17, -21, -22, and -23 are secreted, while anti-inflammatory factors including IL-10 are downregulated. Research conducted over the past several years has focused on inhibiting inflammatory pathways and activating anti-inflammatory factors to improve the quality of life of people with rheumatic diseases. The aim of this paper is to review current knowledge on stimulatory and inhibitory pathways involving the signal transducer and activator of transcription 3 (STAT3). STAT3 has been shown to be one of the crucial factors involved in inflammation and is directly linked with other pro-inflammatory factors and thus is a target of current research on rheumatoid diseases.

NFKB1 promoter -94 insertion/deletion ATTG polymorphism (rs28362491) is associated with severity and disease progression of rheumatoid arthritis through interleukin-6 levels modulation in Egyptian patients

OBJECTIVE

Rheumatoid arthritis (RA) is an inflammatory autoimmune disorder, which can cause progressive and functional disability. Previous data suggests that some inflammatory cytokines are dysregulated in patients with RA. Polymorphisms in the NFKB1 gene were studied in different populations with RA. Specific studies showed that the NFKB1 promoter -94ins/delATTG (rs28362491) polymorphism appears to be correlated with alterations in the IL-6 expression and may lead to disease development. We aimed to evaluate the association between the NFKB1 -94ins/delATTG polymorphism and biochemical, and clinical markers for severity of RA in Egyptian patients.

METHODS

Study subjects included 196 RA patients from the Egyptian population. NFKB1 -94ins/delATTG polymorphism was genotyped by real-time PCR using the TaqMan assay. Concentrations of plasma IL-6 were assessed using the ELISA method.

RESULTS

The frequencies of (del/del + ins/del) genotype in cases with erosive arthritis were significantly increased as compared to cases with non-erosive arthritis (63.0% vs. 47.7%, OR = 1.86, 95% CI: 1.05-3.30, p: 0.043). Carriers of del allele had high activity and severity markers compared with those of ins/ins genotype. The del allele was significantly associated with higher IL-6 levels in a dose-dependent manner. Plasma levels of IL-6 were significantly higher in the del/del (41.4 ± 16.2 pg/ml) and ins/del (19.1 ± 12.4 pg/ml) genotype when compared with the ins/ins genotype (11.4 ± 4.21 pg/ml). In a multivariate analysis of variance, including confounding factors associated with higher IL-6 levels (RF, disease duration, and DAS28), the NFKB1 -94ins/delATTG polymorphism retained its role. Logistic regression analyses revealed that high IL-6 plasma levels independently associated with an increased risk of presenting erosive RA, while -94ins/delATTG polymorphism has no direct association with the progression of erosive arthritis.

CONCLUSION

Our data indicate that the NFKB1 -94ins/delATTG polymorphism contributes to the severity and progression of RA through IL-6 levels modulation in Egyptian patients. Key Points • Carriers of del allele had high activity and severity markers compared with those of ins/ins genotype. • In RA patients, the del allele was significantly associated with higher IL-6 levels in a dose-dependent manner. • IL-6 plasma levels are independently associated with an increased risk of presenting erosive arthritis. • The NFKB1 -94ins/delATTG polymorphism contributes to the severity and progression of RA through IL-6 levels modulation in Egyptian patients.

The potential anti-inflammatory and anti-nociceptive effects of rat hemopressin (PVNFKFLSH) in experimental arthritis

Inflammatory arthritis, such as rheumatoid arthritis (RA), stands out as one of the main sources of pain and impairment to the quality of life. The use of hemopressin (PVNFKFLSH; Hp), an inverse agonist of type 1 cannabinoid receptor, has proven to be effective in producing analgesia in pain models, but its effect on neuro-inflammatory aspects of RA is limited. In this study, antigen-induced arthritis (AIA) was evoked by the intraarticular (i.art.) injection of methylated bovine serum albumin (mBSA) in male Sprague Dawley rats. Phosphate buffered saline (PBS)-injected ipsilateral knee joints or AIA contralateral were used as control. Nociceptive and inflammatory parameters such as knee joint oedema and leukocyte influx and histopathological changes were carried out in addition to the local measurement of interleukins (IL) IL-6, IL-1β, tumor necrosis factor-α and the immunoreactivity of the neuropeptides substance P (SP) and calcitonin gene related peptide (CGRP) in the spinal cord (lumbar L3-5 segments) of AIA rats. For 4 days, AIA rats were treated daily with a single administration of saline, Hp injected (10 or 20 μg/day, i.art.), Hp given orally (20 μg/Kg, p.o.) or indomethacin (Indo; 5 mg/Kg, i.p.). In comparison to the PBS control group, the induction of AIA produced a significant and progressive mono-arthritis condition. The degree of AIA severity progressively compromised the normal walking pattern and impaired mobility over the next four days in relation to PBS-injected rats or contralateral knee joints. In AIA rats, the reduction of the distance between footprints and disturbances of gait evidenced signs of nociception. This response worsened at day 4, and a loss of footprint from the ipsilateral hind paw was evident. Daily treatment of the animals with Hp either i.art. (10 and 20 μg/knee) or p.o. (20 μg/Kg) as well as Indo (5 mg/Kg, i.p.) ameliorated the impaired mobility in a time-dependent manner (P < 0.05). In parallel, the AIA-injected ipsilateral knee joints reach a peak of swelling 24 h after AIA induction, which persisted over the next four days in relation to PBS-injected rats or contralateral knee joints. There was a significant but not dose-dependent inhibitory effect produced by all dosages and routes of Hp treatments on AIA-induced knee joint swelling (P < 0.05). In addition, the increased synovial levels of MPO activity, total leukocytes number and IL-6, but not IL-1β, were significantly reduced by the lower i.art. dose of Hp. In conclusion, these results successfully demonstrate that Hp may represent a novel therapeutic strategy to treat RA, an effect which is unrelated to the proinflammatory actions of the neuropeptides CGRP and SP.

IL-6 but Not TNFα Levels Are Associated With Time to Pregnancy in Female Rheumatoid Arthritis Patients With a Wish to Conceive

Fertility issues are common amongst women with rheumatoid arthritis (RA). Interleukin 6 (IL-6) and tumor necrosis factor alpha (TNFα), known key players in RA pathogenesis, have been associated with reproductive disorders. This study investigates the role of these cytokines in decreased fertility in women with active RA. Preconception cytokine measurements of 61 patients from the PARA-cohort, a prospective study on RA and pregnancy, were studied in relation to time to pregnancy as a measure for fertility. IL-6 levels were higher in patients with a time to pregnancy longer than 1 year (p = 0.016). Survival analysis of patients stratified by high or low serum IL-6 levels, shows a prolonged time to pregnancy in the high IL-6 group (p = 0.045). Univariate cox regression analysis of IL-6 in relation to time to pregnancy as well as multivariate cox regression analysis correcting for age, disease activity, nulliparity, NSAID use and prednisone use were performed, with hazards ratios for log transformed IL-6 of 0.68 (95% CI: 0.51–0.93, p = 0.015) and 0.66 (95% CI: 0.43–0.99, p = 0.044), respectively. For TNFα, no association with time to pregnancy was found. This study shows that high IL-6, but not TNFα, is associated with decreased fertility in women with RA. This finding provides a rationale to therapeutically target the IL-6 pathway in the time period before pregnancy. More research in the form of large cohort studies on drug safety and the effect of bDMARDS on fertility is needed for implementation of treatment strategies directed at fertility issues in women with RA.

Construction of CII-Specific CAR-T to Explore the Cytokine Cascades Between Cartilage-Reactive T Cells and Chondrocytes

Cytokine cascades exist in many autoimmune disorders which amplify and sustain the autoimmune process and lead to chronic inflammatory injury to the host tissues. Increasing evidence indicates that chondrocytes can interact with T cells, which may be a crucial event in inflammatory arthritis. To address the reciprocal influences of cartilage-reactive T cells and chondrocytes, we constructed cartilage-reactive T cells by developing a type II collagen-specific chimeric antigen receptor (CII-CAR). An in vitro co-culture model of CII-CAR-T cells and fresh cartilage was developed, in which CII-CAR-T displayed specific proliferative capacity and cytokine release against fresh cartilage samples, and chondrocytes could respond to CII-CAR-T cells by secreting IL-6. The proposed model will help us to explore the possible cytokine cascades between cartilage-reactive T cells and cartilage.

Autologous extracellular Hsp70 exerts a dual role in rheumatoid arthritis

Extracellular heat shock proteins (Hsp) influence the adaptive immune response and may ameliorate pathogenesis of autoimmune diseases. While some preclinical observations suggest that highly conserved bacterial and/or murine Hsp70 peptides have potential utility in treatment of rheumatoid arthritis (RA) via induction of T regulatory cells (Treg), the role of extracellular inducible human Hsp70 in adaptive immune processes requires further investigation. The present study evaluated Hsp70 influence on inflammatory cytokine-mediated modulation of T cell immunophenotype in ways that influence RA onset and severity. Initial experiments in the present investigation revealed that serum levels of Hsp70 are approximately 2-fold higher in RA patients versus healthy control subjects. To explore the effect of extracellular Hsp70 on key processes underlying the adaptive immune system, the effects of a highly pure, substrate-, and endotoxin-free human Hsp70 on polarization of the T helper cell subpopulations, including CD4+IL-17+ (Th17), CD4+FoxP3+ (Treg), CD4+IFN-γ+ (Th1), and CD4+IL-4+ (Th2), were studied in naïve human peripheral blood mononuclear cell (PBMC) cultures stimulated with anti-CD3/28 mAb. Major findings included an observation that while Hsp70 treatment increased Th17 frequencies and Th17/Treg ratio, the frequency of Th1 cells and the Th1/Th2 ratio were significantly decreased in the Hsp70-treated PBMC cultures. Moreover, data shown here provides preliminary suggestion that major contributing Hsp70-mediated immunomodulation includes interleukin 6 (IL-6) influence on Th17/Treg and Th1/Th2, since expression of this inflammatory cytokine is enhanced by in vitro Hsp70 treatment. These results are nevertheless preliminary and require further investigation to validate the above model.

Regulatory T Cell Plasticity and Stability and Autoimmune Diseases

CD4⁺CD25⁺ regulatory T cells (Tregs) are a class of CD4⁺ T cells with immunosuppressive functions that play a critical role in maintaining immune homeostasis. However, in certain disease settings, Tregs demonstrate plastic differentiation, and the stability of these Tregs, which is characterized by the stable expression or protective epigenetic modifications of the transcription factor Foxp3, becomes abnormal. Plastic Tregs have some features of helper T (Th) cells, such as the secretion of Th-related cytokines and the expression of specific transcription factors in Th cells, but also still retain the expression of Foxp3, a feature of Tregs. Although such Th-like Tregs can secrete pro-inflammatory cytokines, they still possess a strong ability to inhibit specific Th cell responses. Therefore, the plastic differentiation of Tregs not only increases the complexity of the immune circumstances under pathological conditions, especially autoimmune diseases, but also shows an association with changes in the stability of Tregs. The plastic differentiation and stability change of Tregs play vital roles in the progression of diseases. This review focuses on the phenotypic characteristics, functions, and formation conditions of several plastic Tregs and also summarizes the changes of Treg stability and their effects on inhibitory function. Additionally, the effects of Treg plasticity and stability on disease prognosis for several autoimmune diseases were also investigated in order to better understand the relationship between Tregs and autoimmune diseases.

Low levels of pro-resolving lipid mediators lipoxin-A4, resolvin-D1 and resolvin-E1 in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is a disease in which joint inflammation is at the forefront but the whole body is affected, and prevention of inflammation is the main treatment approach. Lipoxins (LXs) and resolvins (Rvs) are critical molecules in the resolution of inflammation. In this study, we aimed to investigate the role of LXs and Rvs in the RA pathogenesis. To this end, we measured the LXA 4, RvD 1, RvE 1 levels, and inflammatory cytokines and chemokines IL-6, IL-8, IL-10, IL-17a, IL-22 and MCP-1 in patients with RA and healthy individuals. We found that the LXA4, RvD1, RvE1 levels of the active RA cases were significantly lower than in remission RA and healthy individuals, but the levels of inflammatory cytokines and chemokines were significantly higher. The decreases in LXs and Rvs were independent of disease activity, suggesting that there might be an impairment of LX and Rvs synthesis or catabolism in patients with RA.

Potential Role of Anti-interleukin (IL)-6 Drugs in the Treatment of COVID-19: Rationale, Clinical Evidence and Risks

The epidemic due to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection has been spreading globally, raising increasing concerns. This public health emergency has triggered a race to find medications to improve the prognosis of this disease. There is currently great interest in drug repositioning to manage SARS-CoV-2 infection, that is, the evaluation of the potential benefits of a drug that has already been proven safe and effective in humans for other approved indications. As interleukin-6 (IL-6) acts as a key driver of the inflammation associated with coronavirus disease 2019 (COVID-19), IL-6 and IL-6 receptor (IL-6R) inhibition appear to be promising targets for the treatment of COVID-19 patients. It is important to critically analyze the available evidence concerning the use of the available anti-IL-6 (siltuximab) and anti-IL-6R (tocilizumab and sarilumab) agents in COVID-19 patients, in terms of both benefit and risk. In this review, the pathogenesis of the cytokine storm induced by COVID-19, the role of IL-6 in this cytokine storm, the rationale for the use of anti-IL-6 agents, and key information on potential benefits and safety monitoring of these biologicals in COVID-19 patients is discussed.

Exploring the therapeutic promise of targeting HMGB1 in rheumatoid arthritis

High mobility group box-1 (HMGB1) protein is a diverse, single polypeptide moiety, present in mammalian eukaryotic cells. In response to stimuli, this nuclear protein is actively secreted in to the extracellular compartment or passively released by the necrotic cells, in order to mediate inflammatory responses, by forming complexes with IL-1α, IL-1β, LPS and other moieties, and binding to RAGE, TLR and other receptor ligands, initiating downstream, signaling processes. This molecule acts as a proinflammatory cytokine and contributes to the progression of diseases like, acute lung injury, autoimmune liver damage, graft rejection immune response and arthritis. Small concentrations of HMGB1 are released during apoptosis, which facilitates oxidative regulation on Cys106, and propagates immune inactivating tolerogenic signals in the body. The review portrays the role of HMGB1 in rheumatoid arthritis, evidently supported by pre-clinical and clinical investigations, demonstrating extensive HMGB1 expression in synovial tissue and fluid as well as serum, excessive expression of transduction receptor signaling molecules, bone remodeling and uncontrolled expression of bone destroying osteoclastogenesis, resulting in destruction of articular cartilage, bone deformation and synovial proliferation, alleviating the pathogenesis in RA disease. Moreover, the review highlights the therapeutic regime targeting HMGB1, facilitating inhibition of its actions and release into the extracellular compartment, to ameliorate the destructive events that prevail in rheumatoid arthritis.

Hydroxychloroquine in rheumatic autoimmune disorders and beyond

Initially used as antimalarial drugs, hydroxychloroquine (HCQ) and, to a lesser extent, chloroquine (CQ) are currently being used to treat several diseases. Due to its cost‐effectiveness, safety and efficacy, HCQ is especially used in rheumatic autoimmune disorders (RADs), such as systemic lupus erythematosus, primary Sjögren's syndrome and rheumatoid arthritis. Despite this widespread use in the clinic, HCQ molecular modes of action are still not completely understood. By influencing several cellular pathways through different mechanisms, CQ and HCQ inhibit multiple endolysosomal functions, including autophagy, as well as endosomal Toll‐like receptor activation and calcium signalling. These effects alter several aspects of the immune system with the synergistic consequence of reducing pro‐inflammatory cytokine production and release, one of the most marked symptoms of RADs. Here, we review the current knowledge on the molecular modes of action of these drugs and the circumstances under which they trigger side effects. This is of particular importance as the therapeutic use of HCQ is expanding beyond the treatment of malaria and RADs.

Stevens Johnson Syndrome in a Patient with Giant Cell Arteritis During Short Term Tocilizumab Therapy

This case report represents a rare life-threatening hypersensitivity reaction of tocilizumab drug when it is used to treat giant cell arteritis. An elderly female with history of bilateral giant cell arteritis with anterior ischemic optic neuropathy of the right eye was started on tocilizumab after developing glucocorticoid-related complications. She received one month of the tocilizumab therapy along with the prednisone taper. The patient initially developed sinus and mucosal edema, presented as drooling with mild tongue and lip swelling. It eventually progressed into development of new onset of erythematous macules and flaccid bullae which was biopsy-confirmed Stevens Johnson syndrome. Tocilizumab drug was immediately discontinued and she was treated with supportive care. The goal of this report is to present the first detailed case of presumed tocilizumab-induced Steven Johnson syndrome which emphasizes the importance of post-marketing surveillance and collection of data on adverse events of this drug.

Mitigation of Rheumatic Arthritis in a Rat Model via Transdermal Delivery of Dapoxetine HCl Amalgamated as a Nanoplatform: In vitro and in vivo Assessment

Purpose

Dapoxetine HCl (DH), a selective serotonin reuptake inhibitor, may be useful for the treatment of rheumatic arthritis (RA). The purpose of this study was to investigate the therapeutic efficacy of transdermal delivery of DH in transethosome nanovesicles (TENVs). This novel delivery of DH may overcome the drawbacks associated with orally administered DH and improve patient compliance.

Methods

DH-TENV formulations were prepared using an injection- sonication method and optimized using a 3³ Box-Behnken-design with Design Expert^® software. The TENV formulations were assessed for entrapment efficiency (EE-%), vesicle size, zeta potential, in vitro DH release, and skin permeation. The tolerability of the optimized DH-TENV gel was investigated using a rat skin irritation test. A pharmacokinetic analysis of the optimized DH-TENV gel was also conducted in rats. Moreover, the anti-RA activity of the optimized DH-TENV gel was assessed based on the RA-specific marker anti-cyclic cirtullinated peptide antibody (anti-CCP), the cartilage destruction marker cartilage oligomeric matrix protein (COMP) and the inflammatory marker interleukin-6 (IL-6). Level of tissue receptor activator of nuclear factor kappa-Β ligand (RANKL) were also assessed.

Results

The optimized DH-TENV formulation involved spherical nanovesicles that had an appropriate EE- % and skin permeation characteristic. The DH-TENV gel was well tolerated by rats. The pharmacokinetics analysis showed that the optimized DH-TENV gel boosted the bioavailability of the DH by 2.42- and 4.16-fold compared to the oral DH solution and the control DH gel, respectively. Moreover, it significantly reduced the serum anti-CCP, COMP and IL-6 levels and decreased the RANKL levels. Furthermore, the DH-TENV gel attenuated histopathological changes by almost normalizing the articular surface and synovial fluid.

Conclusion

The results indicate that DH-TENVs can improve transdermal delivery of DH and thereby alleviate RA.

Virus-specific T-cell therapies for patients with primary immune deficiency

Viral infections are common and are potentially life-threatening in patients with moderate to severe primary immunodeficiency disorders. Because T-cell immunity contributes to the control of many viral pathogens, adoptive immunotherapy with virus-specific T cells (VSTs) has been a logical and effective way of combating severe viral disease in immunocompromised patients in multiple phase 1 and 2 clinical trials. Common viral targets include cytomegalovirus, Epstein-Barr virus, and adenovirus, though recent published studies have successfully targeted additional pathogens, including HHV6, BK virus, and JC virus. Though most studies have used VSTs derived from allogenic stem cell donors, the use of banked VSTs derived from partially HLA-matched donors has shown efficacy in multicenter settings. Hence, this approach could shorten the time for patients to receive VST therapy thus improving accessibility. In this review, we discuss the usage of VSTs for patients with primary immunodeficiency disorders in clinical trials, as well as future potential targets and methods to broaden the applicability of virus-directed T-cell immunotherapy for this vulnerable patient population.

MicroRNA let-7g-5p alleviates murine collagen-induced arthritis by inhibiting Th17 cell differentiation

Rheumatoid arthritis (RA) is a chronic and systemic autoimmune disease with complicated pathogenesis. IL-17-producing T helper cells (Th17) are important players in the RA process. Despite numerous researches have proven that microRNAs (miRNAs) are crucial to regulate autoimmune diseases including RA, the effect of miRNAs on Th17 cell differentiation and function in the RA progress is not clear. Here, our results showed that the expression of miRNA let-7g-5p was substantially lower in RA patients and CIA mice compared with healthy controls, accompanied by the increased Th17 cell population. Furthermore, the inhibition of let-7g-5p on Th17 cell differentiation and function were verified in vitro. Notably, the disease severity in CIA mice was significantly alleviated after the treatment of let-7g-5p mimics. In addition, let-7g-5p mimics treatment markedly down-regulated the frequency of Th17 cells in CIA mice. Taken together, our findings indicate that let-7g-5p can ameliorate CIA through blocking the differentiation of Th17 cells, which may be a novel strategy to treat autoimmune diseases such as RA.

RA-map: building a state-of-the-art interactive knowledge base for rheumatoid arthritis

Rheumatoid arthritis (RA) is a progressive, inflammatory autoimmune disease of unknown aetiology. The complex mechanism of aetiopathogenesis, progress and chronicity of the disease involves genetic, epigenetic and environmental factors. To understand the molecular mechanisms underlying disease phenotypes, one has to place implicated factors in their functional context. However, integration and organization of such data in a systematic manner remains a challenging task. Molecular maps are widely used in biology to provide a useful and intuitive way of depicting a variety of biological processes and disease mechanisms. Recent large-scale collaborative efforts such as the Disease Maps Project demonstrate the utility of such maps as versatile tools to organize and formalize disease-specific knowledge in a comprehensive way, both human and machine-readable. We present a systematic effort to construct a fully annotated, expert validated, state-of-the-art knowledge base for RA in the form of a molecular map. The RA map illustrates molecular and signalling pathways implicated in the disease. Signal transduction is depicted from receptors to the nucleus using the Systems Biology Graphical Notation (SBGN) standard representation. High-quality manual curation, use of only human-specific studies and focus on small-scale experiments aim to limit false positives in the map. The state-of-the-art molecular map for RA, using information from 353 peer-reviewed scientific publications, comprises 506 species, 446 reactions and 8 phenotypes. The species in the map are classified to 303 proteins, 61 complexes, 106 genes, 106 RNA entities, 2 ions and 7 simple molecules. The RA map is available online at ramap.elixir-luxembourg.org as an open-access knowledge base allowing for easy navigation and search of molecular pathways implicated in the disease. Furthermore, the RA map can serve as a template for omics data visualization.

Relationship between polymorphisms in -572G/C interleukin 6 promoter gene polymorphisms (rs1800796) and risk of rheumatoid arthritis: A meta-analysis

AIMS

This meta-analysis was aimed to investigate the association between -572G/C interleukin (IL)-6 gene polymorphism and occurrence risk of rheumatoid arthritis (RA).

METHODS

Literature search was conducted in PubMed, Embase, Springer and Google Scholar up to November 2018. The pooled odds ratios (ORs) and 95% confidence interval (CI) were calculated by Revman 5.3.

RESULTS

A total of six case-control studies were included in this meta-analysis. In the allele model (G vs C), homozygous gene model (GG vs CC), recessive gene model (GG vs GC + CC), and dominant gene model (GG + GC vs CC), the pooled estimate indicated there was significant association between -572G/C IL-6 gene polymorphism and risk of RA. However, no significant statistical results were found in meta-analyses of heterozygote gene models.

CONCLUSIONS

The -572G/C IL-6 gene polymorphism is associated with the risk of RA. The GG genotype may be the main contributor in increasing susceptibility to RA.

A validated single-cell-based strategy to identify diagnostic and therapeutic targets in complex diseases

Background

Genomic medicine has paved the way for identifying biomarkers and therapeutically actionable targets for complex diseases, but is complicated by the involvement of thousands of variably expressed genes across multiple cell types. Single-cell RNA-sequencing study (scRNA-seq) allows the characterization of such complex changes in whole organs.

Methods

The study is based on applying network tools to organize and analyze scRNA-seq data from a mouse model of arthritis and human rheumatoid arthritis, in order to find diagnostic biomarkers and therapeutic targets. Diagnostic validation studies were performed using expression profiling data and potential protein biomarkers from prospective clinical studies of 13 diseases. A candidate drug was examined by a treatment study of a mouse model of arthritis, using phenotypic, immunohistochemical, and cellular analyses as read-outs.

Results

We performed the first systematic analysis of pathways, potential biomarkers, and drug targets in scRNA-seq data from a complex disease, starting with inflamed joints and lymph nodes from a mouse model of arthritis. We found the involvement of hundreds of pathways, biomarkers, and drug targets that differed greatly between cell types. Analyses of scRNA-seq and GWAS data from human rheumatoid arthritis (RA) supported a similar dispersion of pathogenic mechanisms in different cell types. Thus, systems-level approaches to prioritize biomarkers and drugs are needed. Here, we present a prioritization strategy that is based on constructing network models of disease-associated cell types and interactions using scRNA-seq data from our mouse model of arthritis, as well as human RA, which we term multicellular disease models (MCDMs). We find that the network centrality of MCDM cell types correlates with the enrichment of genes harboring genetic variants associated with RA and thus could potentially be used to prioritize cell types and genes for diagnostics and therapeutics. We validated this hypothesis in a large-scale study of patients with 13 different autoimmune, allergic, infectious, malignant, endocrine, metabolic, and cardiovascular diseases, as well as a therapeutic study of the mouse arthritis model.

Conclusions

Overall, our results support that our strategy has the potential to help prioritize diagnostic and therapeutic targets in human disease.

Electronic supplementary material

The online version of this article (10.1186/s13073-019-0657-3) contains supplementary material, which is available to authorized users.

IL6Rα function in myeloid cells modulates the inflammatory response during irritant contact dermatitis

Irritant contact dermatitis (ICD) is characterized by epidermal hyperplasia, infiltration of leucocytes into lesional skin and inflammatory cytokine release. The cellular infiltrate during ICD comprises primarily cells of the myeloid lineage. Our group has previously shown that the cytokine IL-6 confers a protective effect to lesional skin during ICD. How IL-6Rα function in myeloid cells is involved in the inflammatory response during ICD is, however, unknown. In the present study, utilizing a chemical model of ICD, it is shown that mice with a myeloid-specific knockout of the IL-6Rα (IL-6Rα^Δmyeloid ) display an exaggerated inflammatory response to benzalkonium chloride (BKC) and Jet propellant-8 (JP8) fuel, two well-characterized irritants relative to littermate control. Results from immunohistochemical and flow cytometric analyses revealed that IL-6Rα^Δmyeloid mouse skin displayed increased epidermal hyperplasia and inflammatory monocyte influx into lesional skin but lower numbers of resident macrophages relative to littermate controls after irritant exposure. Multiplex immunoassay revealed significantly higher levels of pro-inflammatory cytokines IL-1α and TNF-α, but reduced expression of chemokine proteins including CCL2-5, CCL7, CCL11, CXCL1 and CXCL10 in IL-6Rα^Δmyeloid mouse skin relative to littermate control following irritant exposure. These results highlight a previously unknown role of IL-6Rα function in myeloid cells in modulating the inflammatory response and myeloid population dynamics during ICD.

Regulatory T cells: the future of autoimmune disease treatment

Introduction: CD4 + T regulatory cells (Tregs) have been described as the most potent immunosuppressive cells in the human body. They have been found to control autoimmunity, and clinical attempts have been made to apply them to treat autoimmune diseases. Some specific pathways utilized by Tregs in the regulation of immune response or Tregs directly as cellular products are tested in the clinic. Areas covered: Here, we present recent advances in the research on the biology and clinical applications of Tregs in the treatment of autoimmune diseases. Expert opinion: Regulatory T cells seem to be a promising tool for the treatment of autoimmune diseases. The development of both cell-based therapies and modern pharmacotherapies which affect Tregs may strongly improve the treatment of autoimmune disorders. Growing knowledge about Treg biology together with the latest biotechnology tools may give an opportunity for personalized therapies in these conditions.

Dichotomy of Local Th1- and Systemic Th2/Th3-Dependent Types of Immune Response in Rheumatoid Arthritis

Biomarkers of activity of rheumatoid arthritis were analyzed in the blood serum and synovial fluid of affected joints in 84 patients. Significant differences between the serum and synovial fluid levels were revealed for 10 of 17 analyzed biomarkers; the levels of IgM and proinflammatory cytokines TNFα, IL-1β, IFNγ, and IL-6 were higher in the synovial fluid. The concentration of IL-10 in the synovial fluid was also elevated. In the peripheral blood, the content of antinuclear antibodies, circulating immune complexes, and cytokines IL-4 and TGF-β was elevated. These findings attest to the development of local Th1 type immune response in affected joints paralleled by compensatory elevation of immunosuppressive cytokine IL-10 and systemic Th2/Th3 type immune response (judging from peripheral blood parameters) in patients with rheumatoid arthritis.

Targeting interleukin-6 as a strategy to overcome stroma-induced resistance to chemotherapy in gastric cancer

Background

Although the tumor stroma in solid tumors like gastric cancer (GC) plays a crucial role in chemo-resistance, specific targets to inhibit the interaction between the stromal and cancer cells have not yet been utilized in clinical practice. The present study aims to determine whether cancer-associated fibroblasts (CAFs), a major component of the tumor stroma, confer chemotherapeutic resistance to GC cells, and to discover potential targets to improve chemo-response in GC.

Methods

To identify CAF-specific proteins and signal transduction pathways affecting chemo-resistance in GC cells, secretome and transcriptome analyses were performed. We evaluated the inhibiting effect of CAF-specific protein in in vivo and in vitro models and investigated the expression of CAF-specific protein in human GC tissues.

Results

Secretome and transcriptome data revealed that interleukin-6 (IL-6) is a CAF-specific secretory protein that protects GC cells via paracrine signaling. Furthermore, CAF-induced activation of the Janus kinase 1-signal transducer and activator of transcription 3 signal transduction pathway confers chemo-resistance in GC cells. CAF-mediated inhibition of chemotherapy-induced apoptosis was abrogated by the anti-IL-6 receptor monoclonal antibody tocilizumab in various experimental models. Clinical data revealed that IL-6 was prominently expressed in the stromal portion of GC tissues, and IL-6 upregulation in GC tissues was correlated with poor responsiveness to chemotherapy.

Conclusions

Our data provide plausible evidence for crosstalk between GC cells and CAFs, wherein IL-6 is a key contributor to chemoresistance. These findings suggest the potential therapeutic application of IL-6 inhibitors to enhance the responsiveness to chemotherapy in GC.

Electronic supplementary material

The online version of this article (10.1186/s12943-019-0972-8) contains supplementary material, which is available to authorized users.

Humanized Mouse Models of Rheumatoid Arthritis for Studies on Immunopathogenesis and Preclinical Testing of Cell-Based Therapies

Rodent models of rheumatoid arthritis (RA) have been used over decades to study the immunopathogenesis of the disease and to explore intervention strategies. Nevertheless, mouse models of RA reach their limit when it comes to testing of new therapeutic approaches such as cell-based therapies. Differences between the human and the murine immune system make it difficult to draw reliable conclusions about the success of immunotherapies. To overcome this issue, humanized mouse models have been established that mimic components of the human immune system in mice. Two main strategies have been pursued for humanization: the introduction of human transgenes such as human leukocyte antigen molecules or specific T cell receptors, and the generation of mouse/human chimera by transferring human cells or tissues into immunodeficient mice. Recently, both approaches have been combined to achieve more sophisticated humanized models of autoimmune diseases. This review discusses limitations of conventional mouse models of RA-like disease and provides a closer look into studies in humanized mice exploring their usefulness and necessity as preclinical models for testing of cell-based therapies in autoimmune diseases such as RA.

Interleukin 6: The biology behind the therapy

The cytokine interleukin (IL)−6 performs a diverse portfolio of functions in normal physiology and disease. These functions extend beyond the typical role for an inflammatory cytokine, and IL-6 often displays hormone-like properties that affect metabolic processes associated with lipid metabolism, insulin resistance, and the neuroendocrine system. Consequently, the biology of IL-6 is complex. Recent advances in the field have led to novel interpretations of how IL-6 delivers immune homeostasis in health and yet drives disease pathology during infection, autoimmunity, and cancer. Various biological drugs that target IL-6 are in clinical practice or emerging in clinical trials and pre-clinical development programmes. The challenge is knowing how and when to apply these therapies. In this review, we will explore the biology behind IL-6 directed therapies and identify some key hurdles for future investigation.

Viperin controls chikungunya virus-specific pathogenic T cell IFNγ Th1 stimulation in mice

This study shows that Viperin controls the microenvironment pro-inflammatory response and CD4 T cell–mediated pathogenesis during anti-chikungunya virus immune response in mice.

Chikungunya virus (CHIKV) has been a worldwide threat since its reemergence in La Reunion Island in 2004. Expression of the interferon-stimulated protein Viperin correlates with viral load burden in patients, and studies in mice have demonstrated its role to limit disease severity against CHIKV infection. Using Viperin^−/− mice, we aimed to understand the contribution of Viperin to the T-cell immune response against CHIKV. CD4 T-cell depletion in Viperin^−/− mice showed that increased late acute joint inflammation (5–8 d postinfection) was exclusively mediated by T cells. Specifically, CHIKV-infected Viperin^−/− mice showed an increased INFγ Th1 profile of CD4 T cells, enhanced INFγ stimulation by APCs, an increased INFγ secretion profile in the joint microenvironment, and increased numbers of inflammatory monocytes in virus-infected joints compared with WT mice. Bone marrow grafting experiments showed that Viperin expression in both hematopoietic and non-hematopoietic cells is instrumental in reducing disease severity associated with a CD4 T-cell response.

IL-6 inhibitor for the treatment of rheumatoid arthritis: A comprehensive review

Tocilizumab (TCZ) is an interleukin-6 (IL-6) inhibitor used for the treatment of rheumatoid arthritis (RA). It was developed in 2008, and its effectiveness is supported by evidence from all over the world based on its first decade of use. Although the overall efficacy and safety profiles of TCZ are similar to those of tumor necrosis factor (TNF) inhibitors, TCZ displays certain differences. The most notable advantage of TCZ is its usefulness as a monotherapy. Additionally, TCZ is favorable in the improvement of systemic inflammatory symptoms such as anemia and fatigue. The low immunogenicity of TCZ contributes favorably to long-term drug retention. Due to frequent relapse after TCZ cessation, TCZ use should be tapered beyond remission. During TCZ therapy, C-reactive protein (CRP) is unable to recognize disease activity and the severity of infection. The most common adverse events (AEs) are infection and abnormalities in laboratory findings including dyslipidemia, neutropenia, thrombocytopenia, and abnormality of liver enzymes. TCZ obscures the symptoms of infection. Therefore, stealth infections without obvious CRP elevation can sometimes cause severe damage to patients. Lower intestinal perforation is an uncommon but serious AE in TCZ therapy. Further clinical investigations will continue to refine the IL-6 inhibitory strategy.

Metabolomics study of the therapeutic mechanism of a Chinese herbal formula on collagen-induced arthritis mice

Wenjinghuoluo (WJHL) prescription, the typical rheumatoid arthritis (RA) treatment compound in traditional Chinese medicine, shows favorable efficacy. The precise mechanism of WJHL on RA therapy is yet to be elucidated. This study aimed to determine the metabolic biomarkers in the early onset of RA and evaluate the regulation effect of WJHL on metabolite levels. Multivariate statistical analysis identified 93 biomarkers by precise MS/MS. These biomarkers played an important role in the regulation of key metabolic pathways associated with collagen-induced arthritis (CIA). A total of 68 biomarkers were related to the treatment of CIA by WJHL therapy. In addition, pathway analysis results showed six and three significant related pathways according to corresponding differential metabolites before and after WJHL therapy. Finally, disease and function prediction of ingenuity pathway analysis indicated that lipid metabolism, small molecule biochemistry, and carbohydrate metabolism were associated functions of WJHL therapy on CIA. Furthermore, top analysis-ready molecules of up-regulated thiamine and down-regulated arachidonic acid maybe the most related metabolites of WJHL therapy on CIA. The present work indicates that a metabolomics platform provides a new insight into understanding the mechanisms of action of natural medicines, such as WJHL.

Wenjinghuoluo (WJHL) prescription, the typical rheumatoid arthritis (RA) treatment compound in traditional Chinese medicine, shows favorable efficacy.

Serum hepcidin level and rheumatoid arthritis disease activity

Objective

The present study aimed to determine the relationship between the serum hepcidin level and disease activity in patients with rheumatoid arthritis (RA).

Methods

This study was conducted on 80 patients with RA (36 cases with anemia of chronic disease [ACD] and 44 patients without ACD). Disease activity was measured by the 28-joint Disease Activity Score based on the erythrocyte sedimentation rate (DAS28-ESR). According to the DAS28-ESR score, 52 and 28 cases were categorized as inactive to moderately active RA (DAS28-ESR≤5.1) and highly active RA (DAS28-ESR>5.1), respectively. In addition, the serum hepcidin level was evaluated in all patients to determine its correlation with the DAS28-ESR score.

Results

There was no significant difference between the RA with ACD and RA without ACD groups in terms of the median (interquartile range) hepcidin level (1207 [985.2] vs. 923.8 [677.3] ng/mL; P=0.57). Likewise, no significant difference was observed between the active RA and inactive to moderately active RA groups in this regard (1131.8 [991.3] vs. 1090.9 [631.4] ng/mL; P=0.53).

Conclusion

Hepcidin has no association with disease activity in RA. Therefore, it is not necessary to measure hepcidin to determine the RA activity.

CD4 T cell loss and Th2 and Th17 bias are associated with the severity of severe fever with thrombocytopenia syndrome (SFTS)

Severe fever with thrombocytopenia syndrome (SFTS) is a newly emerging infectious disease caused by a novel bunyavirus with high mortality. Immune suppression is thought to be crucial in disease progression. However, data on immune responses during SFTS are scarce. This study aimed to evaluate the changes in CD4 T-cell subsets throughout the entirety of infection and analyse their relationships with disease severity in SFTS patients. In parallel with CD4 T-cell depletion, decreased Th1, Th2 and Treg numbers, but comparable Th17-cell numbers, were observed in deceased patients compared with those in surviving patients. Additionally, increased Th2 and Th17-cell percentages in the residual CD4 T-cell population led to aberrant Th2/Th1 and Th17/Treg ratios, which were positively correlated with disease severity. Collectively, our data indicated that CD4 T-cell deficiency, Th2 and Th17 bias were closely correlated with the severity of SFTS, indicating therapeutic potential of early immune interventions to ameliorate disease severity.