Leptin exacerbates collagen-induced arthritis via enhancement of Th17 cell response

Leptin antagonism attenuates hypertension and renal injury in an experimental model of autoimmune disease

Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder that is characterized by B- and T-lymphocyte dysfunction and altered cytokine production, including elevated levels of the adipocytokine leptin. Leptin has various immunomodulatory properties, including promoting the expansion of proinflammatory T lymphocytes and the proliferation and survival of B cells. In the present study, we hypothesized that leptin antagonism would improve B- and T-cell dysfunction and attenuate hypertension in an experimental model of SLE, the NZBWF1 mouse. To test this hypothesis, 28-week-old female control and SLE mice were administered 5 mg/kg of murine leptin superantagonist (LA) or vehicle via ip injection every other day for four weeks. Analysis of peripheral blood immune cell populations showed no changes in total CD45R+ B and CD3+ T cell percentages after treatment with LA. However, SLE mice treated with LA had an improved CD4/CD8 ratio and decreased CD3+CD4-CD8- double negative (DN) T cells. Blood pressure was higher in SLE than in control, and treatment with LA decreased blood pressure in SLE mice. Treatment with LA also delayed the onset of albuminuria and decreased glomerulosclerosis in SLE mice. Renal immune cell infiltration was significantly higher in SLE mice as compared with control, but LA treatment was associated with decreased levels of renal CD4+ T cells. In conclusion, these data suggest that leptin plays a pathogenic role in the development of hypertension in SLE, in part, by promoting the expansion of inflammatory DN T cells and the infiltration of T cells into the kidneys.

Elevated serum leptin may be associated with disease activity and secondary osteoporosis in Chinese patients with rheumatoid arthritis

INTRODUCTION

Rheumatoid arthritis (RA) is a systemic chronic autoimmune disease in adults that is associated with significant joint issues and systemic inflammation. One of the signs of bone damage in RA is osteoporosis (OP). Leptin is an inflammatory protein that has been reported to be related to RA. The potential relationships among leptin, disease activity, and OP in Chinese patients with RA are not well known.

METHODS

In total, 245 patients with RA and 120 healthy controls were included in this study. Detailed data on the clinical characteristics and laboratory features were collected. Information about physical activity and functional status was recorded using specific questionnaires. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA). The MECALL castor-50-hf model X-ray scanner was used for the two-hand (including wrist) photographs.

RESULTS

Serum leptin levels differed significantly between the RA group and healthy control subjects (1.27/3.29 vs. 0.17/0.24, Z=13.29, P<0.001). The positive rate of leptin protein in RA patients was 86.35%, which was higher than that in controls (19.55%) (χ2=28.51, P<0.001). Pearson's correlation test showed that morning stiffness, disease duration, joint swelling, joint tenderness, swollen joint count (SJC), tender joint count (TJC), health assessment questionnaire (HAQ) score, and Sharp-van der Heijde method (Sharp) score were positively correlated with the level of serum leptin (r=0.212, r=0.312, r=0.322, r=0.501, r=0.291, r=0.334, P<0.05). There was a clear increasing trend in the level of serum leptin according to the different disease activity scores and in the 28 joint activity (DAS28) groups (F=13.936, P<0.001). Elevated leptin was a risk factor for increased disease activity and OP according to logistic regression analysis. The median leptin level differed significantly between the normal bone mass group, osteopenia group, and OP group (P<0.001). An increased serum leptin level was a risk factor for RA-induced osteoporosis according to logistic regression analysis (P<0.001).

CONCLUSION

These results suggest that the level of serum leptin is associated with disease activity and secondary OP among Chinese patients with RA. Key Points • Serum leptin levels in RA patients are higher than those in normal control group. • Leptin was associated with disease activity. • Leptin was associated with the occurrence of systemic osteoporosis and affects bone erosion in RA patients.

Metabolic influences on T cell in psoriasis: a literature review

Psoriasis is a systemic inflammatory disease that frequently coexists with various other conditions, such as essential hypertension, diabetes, metabolic syndrome, and inflammatory bowel disease. The association between these diseases may be attributed to shared inflammatory pathways and abnormal immunomodulatory mechanisms. Furthermore, metabolites also play a regulatory role in the function of different immune cells involved in psoriasis pathogenesis, particularly T lymphocytes. In this review, we have summarized the current research progress on T cell metabolism in psoriasis, encompassing the regulation of metabolites in glucose metabolism, lipid metabolism, amino acid metabolism, and other pathways within T cells affected by psoriasis. We will also explore the interaction and mechanism between psoriatic metabolites and immune cells. Moreover, we further discussed the research progress of metabolomics in psoriasis to gain a deeper understanding of its pathogenesis and identify potential new therapeutic targets through identification of metabolic biomarkers associated with this condition.

Adipokines in Rheumatoid Arthritis: Emerging Biomarkers and Therapeutic Targets

Rheumatoid arthritis (RA) is a chronic inflammatory disease manifested by joint involvement, extra-articular manifestations, and general symptoms. Adipose tissue, previously perceived as an inert energy storage organ, has been recognised as a significant contributor to RA pathophysiology. Adipokines modulate immune responses, inflammation, and metabolic pathways in RA. Although most adipokines have a pro-inflammatory and aggravating effect on RA, some could counteract this pathological process. The coexistence of RA and sarcopenic obesity (SO) has gained attention due to its impact on disease severity and outcomes. Sarcopenic obesity further contributes to the inflammatory milieu and metabolic disturbances. Recent research has highlighted the intricate crosstalk between adipose tissue and skeletal muscle, suggesting potential interactions between these tissues in RA. This review summarizes the roles of adipokines in RA, particularly in inflammation, immune modulation, and joint destruction. In addition, it explores the emerging role of adipomyokines, specifically irisin and myostatin, in the pathogenesis of RA and their potential as therapeutic targets. We discuss the therapeutic implications of targeting adipokines and adipomyokines in RA management and highlight the challenges and future directions for research in this field.

The Role of Adipokines in the Pathogenesis of Psoriasis

Psoriasis is a chronic and immune-mediated skin condition characterized by pro-inflammatory cytokines and keratinocyte hyperproliferation. Dendritic cells, T lymphocytes, and keratinocytes represent the main cell subtypes involved in the pathogenesis of psoriasis, while the interleukin-23 (IL-23)/IL-17 pathway enhances the disease progression. Human adipose tissue is an endocrine organ, which secretes multiple proteins, known as adipokines, such as adiponectin, leptin, visfatin, or resistin. Current evidence highlights the immunomodulatory roles of adipokines, which may contribute to the progression or suppression of psoriasis. A better understanding of the complexity of psoriasis pathophysiology linked with adipokines could result in developing novel diagnostic or therapeutic strategies. This review aims to present the pathogenesis of psoriasis and the roles of adipokines in this process.

The Influence of Adipokines on Radiographic Damage in Inflammatory Rheumatic Diseases

Inflammatory rheumatic diseases (IRDs) are complex immune-mediated diseases that are characterized by chronic inflammation of the joints. Rheumatoid arthritis (RA) and spondyloarthritis (SpA), including axial SpA (ax SpA) and psoriatic arthritis (PsA), are the most common forms of IRD. Both RA and ax SpA are characterized by a chronic course with progressive structural modifications, namely, cartilage damage and bone erosions in RA and osteoproliferative changes with spinal ossifications in ax SpA. The adipose tissue is involved in the pathophysiology of IRDs via the release of several proteins, namely, adipokines. Several adipokines with pro-inflammatory effects have been identified, such as leptin, adiponectin, visfatin and resistin. In this review, we discuss the role that adipokines may play in the structural modifications of the peripheral joints and/or axial skeleton. In RA, the role of leptin in structural damage remains controversial, while adiponectin and its high-molecular-weight isoform are known to have an influence on the development of bone erosions and radiographic progression. Resistin also appears to be a potent detrimental adipokine for the joints in RA. In ax SpA, visfatin seems to be an attractive candidate for radiographic progression, while leptin and adiponectin have negative effects on radiographic progression.

Semaphorin 4D induces articular cartilage destruction and inflammation in joints by transcriptionally reprogramming chondrocytes

Proinflammatory cytokines play critical roles in the pathogenesis of joint diseases. Using a mass spectrometry-based cloning approach, we identified Semaphorin 4D (Sema4D) as an inflammatory cytokine that directly promoted cartilage destruction. Sema4d-deficient mice showed less cartilage destruction than wild-type mice in a model of rheumatoid arthritis. Sema4D induced a proinflammatory response in mouse articular chondrocytes characterized by the induction of proteolytic enzymes that degrade cartilage, such as matrix metalloproteinases (MMPs) and aggrecanases. The activation of Mmp13 and Mmp3 expression in articular chondrocytes by Sema4D did not depend on RhoA, a GTPase that mediates Sema4D-induced cytoskeletal rearrangements. Instead, it required NF-κB signaling and Ras-MEK-Erk1/2 signaling downstream of the receptors Plexin-B2 and c-Met and depended on the transcription factors IκBζ and C/EBPδ. Genetic and pharmacological blockade of these Sema4D signaling pathways inhibited MMP induction in chondrocytes and cartilage destruction in femoral head organ culture. Our results reveal a mechanism by which Sema4D signaling promotes cartilage destruction.

The Head-to-Toe Hormone: Leptin as an Extensive Modulator of Physiologic Systems

Leptin is a well-known hunger-sensing peptide hormone. The role of leptin in weight gain and metabolic homeostasis has been explored for the past two decades. In this review, we have tried to shed light upon the impact of leptin signaling on health and diseases. At low or moderate levels, this peptide hormone supports physiological roles, but at chronically higher doses exhibits detrimental effects on various systems. The untoward effects we observe with chronically higher levels of leptin are due to their receptor-mediated effect or due to leptin resistance and are not well studied. This review will help us in understanding the non-anorexic roles of leptin, including their contribution to the metabolism of various systems and inflammation. We will be able to get an alternative perspective regarding the physiological and pathological roles of this mysterious peptide hormone.

Effect of resistance exercise on serum leptin levels in a prospective longitudinal study of women patients with rheumatoid arthritis

Background

Exercise has an anti-inflammatory effect and reduces fat mass. Leptin has been known to be proinflammatory adipokines mainly produced by adipocytes. However, few studies have investigated the association between exercise and changes in serum leptin levels of patients with RA. This study evaluated the effect of an individualized resistance exercise on inflammatory markers including leptin as well as muscle strength and exercise capacity in patients with rheumatoid arthritis (RA).

Methods

A total of 42 age- and sex-matched participants were assigned to a resistance exercise program (60 min, once a week for 12 weeks, and self-exercise twice a week) or to a control group. Muscle strength, exercise capacities, and inflammatory markers such as cytokines and adipokines were assessed at baseline and at 12 weeks follow-up. Longitudinal changes in muscle strength, exercise capacity, cytokines, and adipokines between groups were tested with repeated measures analysis of variance or using the generalized estimating equation, with adjustment for baseline disease activity score 28-C response protein as a covariate.

Results

A total of 37 of 42 female patients with RA completed this prospective intervention study. Grip strength improved significantly in the exercise group (P < 0.05), while no between-group changes were found. Quadriceps contraction power (P for group-time interaction = 0.035 for the right side and P for group-time interaction = 0.012 for the left side) and 6-minute walking distance (P for group-time interaction = 0.021) were all improved significantly in the exercise group compared with the control group. In addition, serum leptin levels were significantly decreased in the exercise group compared with the control group (P for group-time interaction = 5.22 × 10⁻⁵), but not the other cytokines or adipokines. The change in serum leptin levels correlated with the changes in fat mass (Rho = 0.491, P= 0.015) and visceral fat area (Rho = 0.501, P= 0.013).

Conclusion

In addition to muscle strength and exercise capacity, the 12 weeks of individualized resistance exercise reduced serum leptin levels in keeping with body fat mass or visceral fat area, suggesting that serum leptin levels might be a surrogate marker of exercise in RA.

Leptin in Osteoarthritis and Rheumatoid Arthritis: Player or Bystander?

White adipose tissue (WAT) is a specialized tissue whose main function is lipid synthesis and triglyceride storage. It is now considered as an active organ secreting a plethora of hormones and cytokines namely adipokines. Discovered in 1994, leptin has emerged as a key molecule with pleiotropic functions. It is primarily recognized for its role in regulating energy homeostasis and food intake. Currently, further evidence suggests its potent role in reproduction, glucose metabolism, hematopoiesis, and interaction with the immune system. It is implicated in both innate and adaptive immunity, and it is reported to contribute, with other adipokines, in the cross-talking networks involved in the pathogenesis of chronic inflammation and immune-related diseases of the musculo-skeletal system such as osteoarthritis (OA) and rheumatoid arthritis (RA). In this review, we summarize the most recent findings concerning the involvement of leptin in immunity and inflammatory responses in OA and RA.

Herbal Formula Longteng Decoction Promotes the Regression of Synovial Inflammation in Collagen-Induced Arthritis Mice by Regulating Type 2 Innate Lymphocytes

The etiology and pathogenesis of rheumatoid arthritis (RA) have not yet been fully elucidated, with greater adverse drug effects in traditional treatment of RA. It is particularly necessary to develop and study Chinese herbal formula as a supplement and alternative drug for the treatment of RA. The traditional Chinese medicine compound Longteng Decoction (LTD), as an empirical prescription in the treatment of RA in Dongzhimen Hospital of Beijing University of Chinese Medicine, has been widely used in clinic. Type 2 innate lymphocytes (ILC2s) have specific transcription factors and signature cytokines that are very similar to Th cells, which have been proved to be necessary in addressing RA inflammation, and are potential targets for RA prevention and treatment. Our previous studies have confirmed that LTD can intervene in the differentiation of peripheral blood Th17 and Treg cells, reduce joint pain index and swelling degree, shorten the time of morning stiffness, reduce ESR, and inhibit joint inflammation. However, it is unclear whether LTD can promote the regression of RA synovial inflammation by regulating the immune response mechanism of ILC2s.Therefore, our team established a collagen-induced arthritis mouse model and conducted an experimental study with LTD as the intervention object. The results showed that joint swelling, synovial inflammatory infiltration, and articular cartilage destruction were alleviated in CIA mice after intervention with LTD. The proliferation and differentiation of Th17 inflammatory cells and the secretion of proinflammatory cytokines (IL-17 and IFN-γ) were inhibited. In addition, LTD can also activate ILC2s to secrete the anti-inflammatory cytokine IL-4, activate the STAT6 signaling pathway, and act synergistic with Treg cells to inhibit the infiltration of type M1 macrophages in synovial tissue and promote its transformation to M2 phenotype. Taken together, these results confirm that LTD can be used as an adjunct or alternative to RA therapy by modulating the ILC2s immune response network and slowing down the inflammatory process of synovial tissue.

Inflammatory arthritis increases the susceptibility to acute immune-mediated hepatitis in mice through enhancing leptin expression in T cells

Liver function abnormalities are common in patients with inflammatory arthritis. However, the precise mechanism is still unclear. In this study, inflammatory arthritis was established in mice by subcutaneous injection of complete Freund's adjuvant, and the intravenous injection of concanavalin A (Con A) was employed to induce acute immune-mediated hepatitis in mice. The result showed that the arthritis mice were more susceptible to ConA-induced hepatitis than the control mice, as evidenced by increased hepatic necrosis, elevated serum alanine aminotransferase activity, and raised inflammatory cytokines. Besides, the in vitro assay demonstrated that the T cells from arthritis mice were more sensitive to the Con A stimulation than those from control mice. Moreover, we determined that the level of leptin, a kind of adipokine, was significantly increased in the serum and hepatic T cells of arthritis mice. Interestingly, the data indicated that the enhanced expression of leptin in hepatic T cells is responsible for the hypersensitivity of arthritis mice-derived T cells to Con A challenge. Collectively, our findings demonstrate an unexpected role of leptin in the connection between inflammatory arthritis and acute immune-mediated hepatitis, thus providing new insight into the clinical therapy of arthritis-related liver dysfunction.

Emerging role of leptin in joint inflammation and destruction

Rheumatoid arthritis (RA) is an autoimmune disease characterized by tumor-like hyperplasia and inflammation of the synovium, which causes synovial cell invasion into the bone and cartilage. In RA pathogenesis, various molecules in effector cells (i.e., immune cells and mesenchymal cells) are dysregulated by genetic and environmental factors. Consistent with the early stages of RA, these pathogenic cells cooperate and activate each other directly by cell-to-cell contact or indirectly via humoral factors. Recently, growing evidence has revealed essential role of adipokines, which are multifunctional signal transduction molecules, in the immune system. In this review, we summarize the current understanding of the cross-talk between leptin, one of the most well-known and best-characterized adipokines, and osteoimmunology. Furthermore, we discuss the contribution of leptin to the pathogenesis of RA and its potential mechanisms.

The metabolic hormone leptin promotes the function of TFH cells and supports vaccine responses

Follicular helper T (T_FH) cells control antibody responses by supporting antibody affinity maturation and memory formation. Inadequate T_FH function has been found in individuals with ineffective responses to vaccines, but the mechanism underlying T_FH regulation in vaccination is not understood. Here, we report that lower serum levels of the metabolic hormone leptin associate with reduced vaccine responses to influenza or hepatitis B virus vaccines in healthy populations. Leptin promotes mouse and human T_FH differentiation and IL-21 production via STAT3 and mTOR pathways. Leptin receptor deficiency impairs T_FH generation and antibody responses in immunisation and infection. Similarly, leptin deficiency induced by fasting reduces influenza vaccination-mediated protection for the subsequent infection challenge, which is mostly rescued by leptin replacement. Our results identify leptin as a regulator of T_FH cell differentiation and function and indicate low levels of leptin as a risk factor for vaccine failure.

T follicular helper (TFH) cell numbers are increased after vaccination and fewer of these cells might result in reduced vaccine responses. Here the authors show in mice and humans that leptin promotes T_FH differentiation and that low leptin levels can impair T_FH response to vaccines and virus protection in mice.

Associations of TNFA, IL17A, and RORC mRNA expression levels in peripheral blood leukocytes with obesity-related asthma in adolescents

Obesity is associated with a unique non-T2 asthma phenotype, characterised by a Th17 immune response. Retinoid-related orphan receptor C (RORC) is the master transcription factor for Th17 polarisation. We investigated the association of TNFA, IL17A, and RORC mRNA expression levels with the non-T2 phenotype. We conducted a cross-sectional study in adolescents, subdivided as follows: healthy (HA), allergic asthma without obesity (AA), obesity without asthma (OB), and non-allergic asthma with obesity (NAO). TNFA, IL17A, and RORC mRNA expression in peripheral blood leukocytes were assessed by RT-PCR. NAO exhibited higher TNFA mRNA expression levels than HA or OB, as well as the highest IL17A and RORC mRNA expression levels among the four groups. The best biomarker for discriminating non-allergic asthma among obese adolescents was RORC mRNA expression levels (area under the curve: 0.95). RORC mRNA expression levels were associated with the non-T2 asthma phenotype, hinting at a therapeutic target in obesity-related asthma.

Adiponectin Enhances B-Cell Proliferation and Differentiation via Activation of Akt1/STAT3 and Exacerbates Collagen-Induced Arthritis

Although B cells have been shown to contribute to the pathogenesis of rheumatoid arthritis (RA), the precise role of B cells in RA needs to be explored further. Our previous studies have revealed that adiponectin (AD) is expressed at high levels in inflamed synovial joint tissues, and its expression is closely correlated with progressive bone erosion in patients with RA. In this study, we investigated the possible role of AD in B cell proliferation and differentiation. We found that AD stimulation could induce B cell proliferation and differentiation in cell culture. Notably, local intraarticular injection of AD promoted B cell expansion in joint tissues and exacerbated arthritis in mice with collagen-induced arthritis (CIA). Mechanistically, AD induced the activation of PI3K/Akt1 and STAT3 and promoted the proliferation and differentiation of B cells. Moreover, STAT3 bound to the promoter of the Blimp-1 gene, upregulated Blimp-1 expression at the transcriptional level, and promoted B cell differentiation. Collectively, we observed that AD exacerbated CIA by enhancing B cell proliferation and differentiation mediated by the PI3K/Akt1/STAT3 axis.

The complex role of adipokines in obesity, inflammation, and autoimmunity

The global obesity epidemic is a major contributor to chronic disease and disability in the world today. Since the discovery of leptin in 1994, a multitude of studies have characterized the pathological changes that occur within adipose tissue in the obese state. One significant change is the dysregulation of adipokine production. Adipokines are an indispensable link between metabolism and optimal immune system function; however, their dysregulation in obesity contributes to chronic low-grade inflammation and disease pathology. Herein, I will highlight current knowledge on adipokine structure and physiological function, and focus on the known roles of these factors in the modulation of the immune response. I will also discuss adipokines in rheumatic and autoimmune diseases.

Roles of leptin on the key effector cells of rheumatoid arthritis

Leptin, an adipokine sharing structural characteristics of the long-chain helical cytokine family with the crucial role as a regulator in energy homeostasis, has been paid more and more attention to its immunoregulatory function. Emerging evidence has indicated the roles of leptin on autoimmune diseases such as systemic lupus erythematous (SLE), multiple sclerosis (MS), rheumatoid arthritis (RA) and psoriasis, implying that leptin may be involved in autoimmune disorders. It is very definite that there exists immunocyte dysfunction in RA patients. Growing data has manifested that leptin is increased in both serum and synovial fluid of RA patients compared to healthy controls, suggesting leptin probably takes part in the pathogenesis of RA. The aim of this review is to discuss about what we currently know with regard to the role of leptin in immune system and its effects on RA crucial cells. To clarify the role of leptin in the pathogenesis of RA is beneficial to both the treatment and medical study.

Crossing the barriers: Revisiting the gut feeling in rheumatoid arthritis

To avoid autoimmunity, it is essential to keep the balance between the defence against pathogens and the maintenance of tolerance to self-antigens. Mucosal inflammation may lead to breakdown of tolerance and activation of autoreactive cells. Growing evidence suggests a major contribution of gut microbiota to the onset of chronic, autoimmune inflammatory diseases including rheumatoid arthritis (RA). RA patients show significant differences in the composition of gut microbiota compared to healthy controls, and in murine arthritis models certain bacteria can induce inflammatory Th17 responses or autoantibody production. The gut microbiota plays an important role in regulating the balance between immunogenic and tolerogenic immune responses. The intestinal barrier is the site of the body where most host-microbiota interaction takes place. Certain microbiota or their metabolites can cause a break in homeostasis by affecting the intestinal barrier integrity and permeability. However, an intact intestinal barrier is essential to separate the intestinal epithelium from toxins, microorganisms, and antigens in the gut lumen. This review will focus on the correlation between a leaky gut and the onset of arthritis. Furthermore, it will be discussed how targeting the intestinal barrier function by dietary changes might provide an opportunity to modulate the development of RA.

The Role of Leptin in the Association between Obesity and Psoriasis

Adipose tissue secretes many adipokines which contribute to various metabolic processes, such as blood pressure, glucose homeostasis, inflammation and angiogenesis. The biology of adipose tissue in an obese individual is abnormally altered in a manner that increases the body’s vulnerability to immune diseases, such as psoriasis. Psoriasis is considered a chronic inflammatory skin disease which is closely associated with being overweight and obese. Additionally, secretion of leptin, a type of adipokine, increases dependently on adipose cell size and adipose accumulation. Likewise, high leptin levels also aggravate obesity via development of leptin resistance, suggesting that leptin and obesity are closely related. Leptin induction in psoriatic patients is mainly driven by the interleukin (IL)-23/helper T (Th) 17 axis pathway. Furthermore, leptin can have an effect on various types of immune cells such as T cells and dendritic cells. Here, we discuss the relationship between obesity and leptin expression as well as the linkage between effect of leptin on immune cells and psoriasis progression.

Mini-Review: The Contribution of Adipokines to Joint Inflammation in Inflammatory Rheumatic Diseases

Inflammatory rheumatic diseases (IRD) are complex disorders characterized by chronic inflammation of the joints and related skeletal structures. The most common forms of IRD are rheumatoid arthritis (RA) and spondyloarthritis (SpA), including axial SpA (axSpA) and psoriatic arthritis (PsA). Obesity is a frequent comorbidity in RA and PsA, and to a lesser extend in axial SpA. The association between obesity and IRD may be explained by the release from fat tissue of several bioactive proteins, namely adipokines. Adipokines are involved in the regulation of various processes such as lipid or glucose metabolism, but also inflammation. Adipokines are interrelated with the immune system, with both innate and adaptive immune cell connections. Several adipokines with pro-inflammatory effects have been identified such as leptin, visfatin or resistin. Conversely, adiponectin and more specifically its low molecular weight isoform, is considered to have antiinflammatory properties. In this review, we discuss the contribution of adipokines to the joint inflammation of IRD, the relation they have with immune pathways of these diseases, their links with the structural impact on peripheral joints and/or axial skeleton, and also the influence they may have on the cardiometabolic risk of IRD.

L-PGDS deficiency accelerated the development of naturally occurring age-related osteoarthritis

Osteoarthritis (OA) is the most common musculoskeletal disorder among the elderly. It is characterized by progressive cartilage degradation, synovial inflammation, subchondral bone remodeling and pain. Lipocalin prostaglandin D synthase (L-PGDS) is responsible for the biosynthesis of PGD₂, which has been implicated in the regulation of inflammation and cartilage biology. This study aimed to evaluate the effect of L-PGDS deficiency on the development of naturally occurring age-related OA in mice.

OA-like structural changes were assessed by histology, immunohistochemistry, and micro–computed tomography. Pain related behaviours were assessed using the von Frey and the open-field assays.

L-PGDS deletion promoted cartilage degradation during aging, which was associated with enhanced expression of extracellular matrix degrading enzymes, matrix metalloprotease 13 (MMP-13) and a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS-5), and their breakdown products, C1,2C, VDIPEN and NITEG. Moreover, L-PGDS deletion enhanced subchondral bone changes, but had no effect on its angiogenesis. Additionally, L-PGDS deletion increased mechanical sensitivity and reduced spontaneous locomotor activity. Finally, we showed that the expression of L-PGDS was elevated in aged mice. Together, these findings indicate an important role for L-PGDS in naturally occurring age-related OA. They also suggest that L-PGDS may constitute a new efficient therapeutic target in OA.

Leptin Promoted IL-17 Production from ILC2s in Allergic Rhinitis

Background

Interleukin-17 plays important roles in allergic diseases. Several studies proved that leptin promoted Th17 immune responses by inducing RORγt transcription. ILC2 is an important member of the early stage of immune response. Therefore, we aimed to explore the effect of leptin on the IL-17 production by ILC2 in AR in this study.

Methods

Fifteen AR patients and fifteen healthy controls were enrolled. Serum leptin levels were measured, and their correlation with the frequency of IL-17+ ILC2 cells was analyzed using enzyme-linked immunosorbent assay (ELISA) and flow cytometry. ILC2 was stimulated by leptin, and the expression of IL-17, IL-5, and IL-13 was detected by ELISA. The correlated pathways were confirmed by real-time PCR.

Results

We found that serum leptin and the frequency of IL-17-producing ILC2s in AR were significantly higher compared with those in controls. After being incubated with leptin, the frequency of IL-17+ ILC2 cells and IL-17 production from ILC2 was upregulated compared with that in controls. We also found that leptin induced RORγt and Ahr expression by ILC2. Moreover, leptin-induced IL-17-producing ILC2 concomitantly expressed IL-5 and IL-13.

Conclusions

Our data provide preliminary evidence that leptin-induced IL-17 production from ILC2 cells is dependent on RORγt and Ahr expression and the blockade of leptin may be a promising target for the treatment of AR.

Effect of a Weight Loss Program on Biochemical and Immunological Profile, Serum Leptin Levels, and Cardiovascular Parameters in Obese Dogs

This study aimed to investigate the effects of a weight loss program (WLP) on biochemical and immunological profile, and cardiovascular parameters in a cohort of dogs with naturally occurring obesity. Eleven obese dogs [body condition scoring (BCS), ≥7/9] were enrolled into the study and underwent clinical and cardiovascular examination, and blood testing before (T0) and after 6 months (T1) of WLP. Eleven normal weight (BCS, 4/5) healthy dogs were used as a control (CTR) group. Compared to the CTR group, at T0 obese dogs expressed higher serum leptin concentrations (p < 0.0005) that significantly decreased after weight loss (p < 0.005) but remained higher than the CTR group. Furthermore, obese dogs showed considerably lower levels (p < 0.0005) of regulatory T cell (Treg) compared to the CTR group, but they did not change after weight loss at T1. In obese dogs, tumor necrosis factor (TNF)-α and interleukin (IL)-6 concentrations were substantially reduced at T1 (p < 0.0001 and p < 0.005). Regarding the cardiovascular parameters, only one obese dog was hypertensive at T0, and systolic blood pressure values showed no significant differences at the end of the WLP. The ratio of interventricular septal thickness in diastole to left ventricle internal diameter in diastole (IVSd/LVIDd) was significantly greater in obese dogs at T0 than in the CTR group (p < 0.005). It decreased after weight loss (p < 0.05). In obese dogs, troponin I level significantly reduced with weight loss (p < 0.05), while endothelin-1 level did not differ statistically. The results suggest that the immune dysregulation in the presence of high leptin levels and reduced number of Treg could affect obese dogs as well as humans. Based on our findings, we may speculate that a more complete immune-regulation restore could be obtained by a greater reduction in fat mass and a longer-term WLP. Finally, left ventricular remodeling may occur in some obese dogs. However, in canine species, further studies are needed to investigate the impact of obesity and related WLP on cardiovascular system.

Porphyromonas gingivalis and Lactobacillus rhamnosus GG regulate the Th17/Treg balance in colitis via TLR4 and TLR2

OBJECTIVES

CD4⁺ T cells are the key to many immune-inflammatory diseases mediated by microbial disorders, especially inflammatory bowel disease (IBD). The purpose of this study was to explore how pathogenic and probiotic bacteria directly affect the T helper (Th)17 and T regulatory (Treg) cell balance among CD4⁺ T cells to regulate inflammation.

METHODS

Porphyromonas gingivalis (Pg; ATCC 33277) and Lactobacillus rhamnosus GG (LGG; CICC 6141) were selected as representative pathogenic and probiotic bacteria, respectively. Bacterial extracts were obtained via ultrasonication and ultracentrifugation. Flow cytometry, RT-qPCR, ELISAs, immunofluorescence and a Quantibody cytokine array were used. The dextran sodium sulphate (DSS)-induced colitis model was selected for verification.

RESULTS

The Pg ultrasonicate induced the apoptosis of CD4⁺ T cells and upregulated the expression of the Th17-associated transcription factor RoRγt and the production of the proinflammatory cytokines IL-17 and IL-6, but downregulated the expression of the essential Treg transcription factor Foxp3 and the production of the anti-inflammatory factors TGF-β and IL-10 via the TLR4 pathway. However, LGG extract maintained Th17/Treg homeostasis by decreasing the IL-17⁺ Th17 proportion and increasing the CD25⁺ Foxp3⁺ Treg proportion via the TLR2 pathway. In vivo, Pg-stimulated CD4⁺ T cells aggravated DSS-induced colitis by increasing the Th17/Treg ratio in the colon and lamina propria lymphocytes (LPLs), and Pg + LGG-stimulated CD4⁺ T cells relieved colitis by decreasing the Th17/Treg ratio via the JAK-STAT signalling pathway.

CONCLUSIONS

Our findings suggest that pathogenic Pg and probiotic LGG can directly regulate the Th17/Treg balance via different TLRs.

Leptin induces TNFα-dependent inflammation in acquired generalized lipodystrophy and combined Crohn's disease

Leptin has been shown to modulate intestinal inflammation in mice. However, clinical evidence regarding its immune-stimulatory potential in human Crohn’s disease remains sparse. We here describe a patient with the unique combination of acquired generalized lipodystrophy and Crohn’s disease (AGLCD) featuring a lack of adipose tissue, leptin deficiency and intestinal inflammation. Using mass and flow cytometry, immunohistochemistry and functional metabolic analyses, the AGLCD patient was compared to healthy individuals and Crohn’s disease patients regarding immune cell composition, function and metabolism and the effects of recombinant N-methionylleptin (rLeptin) were evaluated. We provide evidence that rLeptin exerts diverse pro-inflammatory effects on immune cell differentiation and function, including the metabolic reprogramming of immune cells and the induction of TNFα, ultimately aggravating Crohn’s disease in the AGLCD patient, which can be reversed by anti-TNFα therapy. Our results indicate that leptin is required for human immune homeostasis and contributes to autoimmunity in a TNFα-dependent manner.

The adipokine leptin modulates intestinal inflammation in mice. Here the authors describe a patient with inflammatory bowel disease and lipodystrophy, providing evidence that leptin aggravates intestinal inflammation with proinflammatory effects on leukocytes that are reversible by TNFα blockade.

Leptin: an unappreciated key player in SLE

Leptin is the forerunner of the adipokine superfamily and plays a key role in regulating energy expenditure and neuroendocrine function. Researches into leptin put emphasize not only on the metabolic role but also its immunoregulatory effect on immune response through immunocyte activation and cytokine secretion. Leptin acts on receptors that are widespread throughout the body and that are expressed across many tissue types. As a consequence, the abnormal expression of leptin has been found to correlate with a number of diseases, including cancers, autoimmune diseases, and cardiovascular diseases. The significance of leptin in the development of autoimmune diseases is becoming increasingly prominent. Systemic lupus erythematosus (SLE) is a severe atypical autoimmune disease that causes damage to multiple organ systems. It is characterised by the following: impaired clearance of apoptotic cells, loss of tolerance to self-antigens, aberrant activation of T cells and B cells, and chronic inflammation. The heightened immunocyte response in SLE means that these physiological systems are particularly vulnerable to regulation by leptin in addition to being of great significance to the research field. Our current review provides insight into the regulatory roles that leptin plays on immune effector cells in SLE.

The Systemic Immune Response to Collagen-Induced Arthritis and the Impact of Bone Injury in Inflammatory Conditions

Rheumatoid arthritis (RA) is a systemic disease that affects the osteoarticular system, associated with bone fragility and increased risk of fractures. Herein, we aimed to characterize the systemic impact of the rat collagen-induced arthritis (CIA) model and explore its combination with femoral bone defect (FD). The impact of CIA on endogenous mesenchymal stem/stromal cells (MSC) was also investigated. CIA induction led to enlarged, more proliferative, spleen and draining lymph nodes, with altered proportion of lymphoid populations. Upon FD, CIA animals increased the systemic myeloid cell proportions, and their expression of co-stimulatory molecules CD40 and CD86. Screening plasma cytokine/chemokine levels showed increased tumor necrosis factor-α (TNF-α), Interleukin (IL)-17, IL-4, IL-5, and IL-12 in CIA, and IL-2 and IL-6 increased in CIA and CIA+FD, while Fractalkine and Leptin were decreased in both groups. CIA-derived MSC showed lower metabolic activity and proliferation, and significantly increased osteogenic and chondrogenic differentiation markers. Exposure of control-MSC to TNF-α partially mimicked the CIA-MSC phenotype in vitro. In conclusion, inflammatory conditions of CIA led to alterations in systemic immune cell proportions, circulating mediators, and in endogenous MSC. CIA animals respond to FD, and the combined model can be used to study the mechanisms of bone repair in inflammatory conditions.

Autoimmune diseases in China

Autoimmune diseases, such as rheumatoid arthritis, systematic lupus erythematosus and Sjögren's syndrome, are a group of diseases characterized by the activation of immune cells and excessive production of autoantibodies. Although the pathogenesis of these diseases is still not completely understood, studies have shown that multiple factors including genetics, environment and immune responses play important roles in the development and progression of the diseases. In China, there are great achievements in the mechanisms of autoimmune diseases during the last decades. These studies provide new insight to understand the diseases and also shed light on the development of novel therapy.

The Adipokine Network in Rheumatic Joint Diseases

Rheumatic diseases encompass a diverse group of chronic disorders that commonly affect musculoskeletal structures. Osteoarthritis (OA) and rheumatoid arthritis (RA) are the two most common, leading to considerable functional limitations and irreversible disability when patients are unsuccessfully treated. Although the specific causes of many rheumatic conditions remain unknown, it is generally accepted that immune mechanisms and/or uncontrolled inflammatory responses are involved in their etiology and symptomatology. In this regard, the bidirectional communication between neuroendocrine and immune system has been demonstrated to provide a homeostatic network that is involved in several pathological conditions. Adipokines represent a wide variety of bioactive, immune and inflammatory mediators mainly released by adipocytes that act as signal molecules in the neuroendocrine-immune interactions. Adipokines can also be synthesized by synoviocytes, osteoclasts, osteoblasts, chondrocytes and inflammatory cells in the joint microenvironment, showing potent modulatory properties on different effector cells in OA and RA pathogenesis. Effects of adiponectin, leptin, resistin and visfatin on local and systemic inflammation are broadly described. However, more recently, other adipokines, such as progranulin, chemerin, lipocalin-2, vaspin, omentin-1 and nesfatin, have been recognized to display immunomodulatory actions in rheumatic diseases. This review highlights the latest relevant findings on the role of the adipokine network in the pathophysiology of OA and RA.

Plasma Leptin Does Not Reflect the Effect of High Body Mass Index on Disease Activity in Rheumatoid Arthritis

Background: The effect of obesity on disease severity in rheumatoid arthritis (RA) remains controversial. Adipocytes secrete pro-inflammatory cytokines and adipokines which may contribute to RA disease activity. The goal of the present study is to address the association between body mass index (BMI) with plasma levels of leptin, pro-inflammatory cytokines, and RA disease severity.Methods: Fifty RA patients (20 newly diagnosed and 30 under treatment) as well as 30 age- and sex-matched healthy subjects were included in this survey. The plasma levels of leptin and pro-inflammatory cytokines, including TNF-α and IL-6, were measured, and the results were compared among the patients in the three different categories of BMI, including <25, ≥25-30, and ≥30.Results: In our study, a significant positive correlation was observed between disease activity score-28 (DAS-28) and BMI in overweight (OW) RA patients (p = .036 r = 0.440). The plasma levels of leptin were significantly higher in patients group, compared to healthy subjects (p < .05); moreover, leptin levels were significantly higher in OW and obese patients compared to RA patients with normal BMI (p = .011, p = .001, respectively) and also BMI had positive correlation with leptin concentrations just in the newly diagnosed patients (p < .0001, r = 0.748). There was no correlation between leptin and DAS-28. The plasma IL-6 and TNF-α did not show significant differences between RA patients and healthy subjects, and also the plasma leptin did not have any correlation with plasma levels of IL-6 and TNF-α.Conclusion: BMI contribution to RA disease severity is independent of systemic levels of leptin and pro-inflammatory cytokines.

Leptin and Immunological Profile in Obesity and Its Associated Diseases in Dogs

Growing scientific evidence has unveiled increased incidences of obesity in domestic animals and its influence on a plethora of associated disorders. Leptin, an adipokine regulating body fat mass, represents a key molecule in obesity, able to modulate immune responses and foster chronic inflammatory response in peripheral tissues. High levels of cytokines and inflammatory markers suggest an association between inflammatory state and obesity in dogs, highlighting the parallelism with humans. Canine obesity is a relevant disease always accompanied with several health conditions such as inflammation, immune-dysregulation, insulin resistance, pancreatitis, orthopaedic disorders, cardiovascular disease, and neoplasia. However, leptin involvement in many disease processes in veterinary medicine is poorly understood. Moreover, hyperleptinemia as well as leptin resistance occur with cardiac dysfunction as a consequence of altered cardiac mitochondrial metabolism in obese dogs. Similarly, leptin dysregulation seems to be involved in the pancreatitis pathophysiology. This review aims to examine literature concerning leptin and immunological status in obese dogs, in particular for the aspects related to obesity-associated diseases.

Stressed: The Unfolded Protein Response in T Cell Development, Activation, and Function

The unfolded protein response (UPR) is a highly conserved pathway that allows cells to respond to stress in the endoplasmic reticulum caused by an accumulation of misfolded and unfolded protein. This is of great importance to secretory cells because, in order for proteins to traffic from the endoplasmic reticulum (ER), they need to be folded appropriately. While a wealth of literature has implicated UPR in immune responses, less attention has been given to the role of UPR in T cell development and function. This review discusses the importance of UPR in T cell development, homeostasis, activation, and effector functions. We also speculate about how UPR may be manipulated in T cells to ameliorate pathologies.

The Differential Roles of T Cells in Non-alcoholic Fatty Liver Disease and Obesity

Non-alcoholic fatty liver disease (NAFLD) constitutes a spectrum of disease states characterized by hepatic steatosis and is closely associated to obesity and the metabolic syndrome. In non-alcoholic steatohepatitis (NASH), additionally, inflammatory changes and hepatocellular damage are present, representing a more severe condition, for which the treatment is an unmet medical need. Pathophysiologically, the immune system is one of the main drivers of NAFLD progression and other obesity-related comorbidities, and both the innate and adaptive immune system are involved. T cells form the cellular component of the adaptive immune system and consist of multiple differentially active subsets, i.e., T helper (Th) cells, regulatory T (Treg) cells, and cytotoxic T (Tc) cells, as well as several innate T-cell subsets. This review focuses on the role of these T-cell subsets in the pathogenesis of NAFLD, as well as the association with obesity and type 2 diabetes mellitus, reviewing the available evidence from both animal and human studies. Briefly, Th1, Th2, Th17, and Th22 cells seem to have an attenuating effect on adiposity. Th2, Th22, and Treg cells seem to decrease insulin resistance, whereas Th1, Th17, and Tc cells have an aggravating effect. Concerning NAFLD, both Th22 and Treg cells appear to have an overall tempering effect, whereas Th17 and Tc cells seem to induce more liver damage and fibrosis progression. The evidence regarding the role of the innate T-cell subsets is more controversial and warrants further exploration.

Leptin/osteopontin axis contributes to enhanced T helper 17 type responses in allergic rhinitis

BACKGROUND

Recent studies suggest that T helper 17 (Th17) cell subset, a distinct pro-inflammatory CD4 +  T cell lineage, may play an important role in the pathophysiology of allergic rhinitis (AR). However, the regulation of Th17 response in allergic disease is not well characterized.

METHODS

Thirty AR and 30 healthy children were enrolled. Serum leptin and OPN levels were measured, and their correlation with IL-17 expression was analyzed using enzyme-linked immunosorbent assay (ELISA). Th17 cell differentiation and cytokine production in peripheral blood mononuclear cell (PBMCs) stimulated by leptin and OPN and related inhibitors were analyzed by ELISA. AR mice models were also established to verify the effect of leptin and OPN on Th17 cell regulation. Immunoprecipitation was performed to explore the interaction between OPN and leptin in Th17 cells.

RESULTS

Our results showed that elevated serum leptin and OPN in AR children were correlated with serum IL-17 level (r = .53, P < .01). The recombinant leptin and OPN enhanced Th17 responses from PBMCs synergistically through nuclear factor κB (NF-κB), mitogen-activated protein kinase (MAPK), and c-Jun N-terminal kinase (JNK) pathway and β3 integrin receptor. The AR mice showed as more severe Th17 responses and symptoms compared with control mice. Immunoprecipitation showed that OPN and leptin may interact with each other directly, and this process may be mediated by β3 integrin.

CONCLUSIONS

Our data provide evidence that upregulation of leptin and OPN promotes Th17 responses in AR, and this process may be achieved through NF-κB, MAPK, and JNK pathway and β3 integrin.

Obesity, Fat Mass and Immune System: Role for Leptin

Obesity is an epidemic disease characterized by chronic low-grade inflammation associated with a dysfunctional fat mass. Adipose tissue is now considered an extremely active endocrine organ that secretes cytokine-like hormones, called adipokines, either pro- or anti-inflammatory factors bridging metabolism to the immune system. Leptin is historically one of most relevant adipokines, with important physiological roles in the central control of energy metabolism and in the regulation of metabolism-immune system interplay, being a cornerstone of the emerging field of immunometabolism. Indeed, leptin receptor is expressed throughout the immune system and leptin has been shown to regulate both innate and adaptive immune responses. This review discusses the latest data regarding the role of leptin as a mediator of immune system and metabolism, with particular emphasis on its effects on obesity-associated metabolic disorders and autoimmune and/or inflammatory rheumatic diseases.

Changes in Nutritional Status Impact Immune Cell Metabolism and Function

Immune cell function and metabolism are closely linked. Many studies have now clearly demonstrated that alterations in cellular metabolism influence immune cell function and that, conversely, immune cell function determines the cellular metabolic state. Less well understood, however, are the effects of systemic metabolism or whole organism nutritional status on immune cell function and metabolism. Several studies have demonstrated that undernutrition is associated with immunosuppression, which leads to both increased susceptibility to infection and protection against several types of autoimmune disease, whereas overnutrition is associated with low-grade, chronic inflammation that increases the risk of metabolic and cardiovascular disease, promotes autoreactivity, and disrupts protective immunity. Here, we review the effects of nutritional status on immunity and highlight the effects of nutrition on circulating cytokines and immune cell populations in both human studies and mouse models. As T cells are critical members of the immune system, which direct overall immune response, we will focus this review on the influence of systemic nutritional status on T cell metabolism and function. Several cytokines and hormones have been identified which mediate the effects of nutrition on T cell metabolism and function through the expression and action of key regulatory signaling proteins. Understanding how T cells are sensitive to both inadequate and overabundant nutrients may enhance our ability to target immune cell metabolism and alter immunity in both malnutrition and obesity.

Adipokines and inflammation: is it a question of weight?

Obesity has reached epidemic proportions in the Western society and is increasing in the developing world. It is considered as one of the major contributors to the global burden of disability and chronic diseases, including autoimmune, inflammatory and degenerative diseases. Research conducted on obesity and its complications over the last two decades has transformed the outdated concept of white adipose tissue (WAT) merely serving as an energy depot. WAT is now recognized as an active and inflammatory organ capable of producing a wide variety of factors known as adipokines. These molecules participate through endocrine, paracrine, autocrine or juxtacrine crosstalk mechanisms in a great variety of physiological or pathophysiological processes, regulating food intake, insulin sensitivity, immunity and inflammation. Although initially restricted to metabolic activities (regulation of glucose and lipid metabolism), adipokines currently represent a new family of proteins that can be considered key players in the complex network of soluble mediators involved in the pathophysiology of immune/inflammatory diseases. However, the complexity of the adipokine network in the pathogenesis and progression of inflammatory diseases has posed, since the beginning, the important question of whether it may be possible to target the mechanism(s) by which adipokines contribute to disease selectively without suppressing their physiological functions. Here, we explore in depth the most recent findings concerning the involvement of adipokines in inflammation and immune responses, in particular in rheumatic, inflammatory and degenerative diseases. We also highlight several possible strategies for therapeutic development and propose that adipokines and their signalling pathways may represent innovative therapeutic strategies for inflammatory disorders.

Suppression of Lipogenesis via Reactive Oxygen Species-AMPK Signaling for Treating Malignant and Proliferative Diseases

AIMS

Systemic diseases often have common characteristics. The aim of this study was to investigate the feasibility of targeting common pathological metabolism to inhibit the progression of malignant and proliferative diseases.

RESULTS

Gefitinib-resistant (G-R) nonsmall-cell lung cancer (NSCLC) and rheumatoid arthritis (RA) were studied as conditions representative of malignant and proliferative diseases, respectively. Strong lipogenic activity and high expression of sterol regulatory element-binding protein 1 (SREBP1) were found in both G-R NSCLC cells and synovial fibroblasts from RA patients (RASFs). Berberine (BBR), an effective suppressor of SREBP1 and lipogenesis regulated through reactive oxygen species (ROS)/AMPK pathway, selectively inhibited the growth of G-R NSCLC cells and RASFs but not that of normal cells. It effectively caused mitochondrial dysfunction, activated ROS/AMPK pathway, and finally suppressed cellular lipogenesis and cell proliferation. Addition of ROS blocker, AMPK inhibitor, and palmitic acid significantly reduced the effect of BBR. In an in vivo study, treatment of BBR led to significant inhibition of mouse tumor xenograft growth and remarkably slowed down the development of adjuvant-induced arthritis in rats. Innovation and Conclusion: Targeting ROS/AMPK/lipogenesis signaling pathway selectively inhibited the growth of G-R NSCLC cells and the progress of RASFs in vitro and in vivo, which provides a new avenue for treating malignancies and proliferative diseases. Antioxid. Redox Signal. 28, 339-357.

Bidirectional Association Between Psoriasis and Obesity: Benefits and Risks

Psoriasis is a chronic, immune-mediated inflammatory skin disease that is associated with several comorbidities such as obesity. This study was designed to estimate the possibility of utilizing psoriasin, nestin, keratin-16 (Krt16), and interleukin-21 (IL-21) as biochemical markers of psoriasis, to correlate these candidate psoriatic markers with biomarkers of obesity [body mass index (BMI), leptin, and resistin], and to elucidate the bidirectional association between obesity and psoriasis. Blood samples were collected from all participants (n = 108) who were classified according to their BMI into 4 groups: healthy control, obese, psoriatic, and obese psoriatic group. Plasma psoriasin, nestin, Krt16, IL-21, leptin, and resistin were estimated for all subjects. Psoriasin, nestin, Krt16, IL-21, leptin, and resistin were significantly elevated in psoriatic and obese psoriatic groups. However, only leptin, resistin, IL-21, and Krt16 were significantly increased in the obese group compared with the control group. Leptin and resistin showed significant positive correlations with psoriasis area and severity index score, psoriasin, nestin, Krt16, and IL-21. Cutoff values for psoriasin, nestin, Krt16, and IL-21 were 187.5 ng/mL, 1825 pg/mL, 33.1 ng/mL, and 128.6 ng/L, respectively. In conclusion, psoriasin, nestin, Krt16, and IL-21 can be utilized as biochemical markers of psoriasis; these psoriatic markers are significantly positively correlated with obesity biomarkers, and obesity can be considered a risk factor and/or consequence of psoriasis.

B1a cells play a pathogenic role in the development of autoimmune arthritis

Dysregulated functions of B1 cells have been implicated in the disease progression of various autoimmune disorders, but it remains largely unclear whether B1 cells are involved in the pathogenesis of autoimmune arthritis. In this study, we found that peritoneal B1a cells underwent proliferation and migrated to the inflamed joint tissue with upregulated RANKL expression during collagen-induced arthritis (CIA) development in mice. Adoptive transfer of B1a cells exacerbated arthritic severity and joint damage while intraperitoneal depletion of B1 cells ameliorated both arthritic symptoms and joint pathology in CIA mice. In culture, RANKL-expressing B1a cells significantly promoted the expansion of osteoclasts derived from bone marrow cells, which were in accord with the in vivo findings of increased osteoclastogenesis in CIA mice transferred with B1a cells. Together, these results have demonstrated a pathogenic role of B1a cells in the development of autoimmune arthritis through RANKL-mediated osteoclastogenesis.

Increased serum concentrations of IL-1 beta, IL-21 and Th17 cells in overweight patients with rheumatoid arthritis

Backgrounds

Obesity is associated with worse disease activity and drug responses in patients with rheumatoid arthritis (RA). However, the immunological mechanisms responsible for the relationship between RA and obesity have not yet been clarified in detail. This study aimed to elucidate the immunological mechanisms contributing to the pathogenesis of RA in overweight patients.

Methods

The frequencies of CD4⁺ T cell, B cell and monocyte subsets were analyzed in RA (n = 81) and healthy donors (n = 99) by flow cytometry, and were compared between three groups (body mass index (BMI) <20,  ≥20 to 25, >25). Serum cytokines were measured using multiplex ELISA. Gene expression was analyzed by quantitative PCR. Clinical information was extracted from medical records.

Results

The frequencies of T helper (Th)17 (CD4⁺CD45RA-CXCR5-CXCR3-CCR6⁺) cells and plasmablasts (PB) were significantly increased in patients with RA with BMI >25. Significant correlation was observed between BMI and Th17 cells in patients with RA. No significant differences in cell frequencies between the three BMI groups were observed in the healthy donors. Serum interleukin (IL)-1β and IL-21 significantly correlated with BMI in RA patients. Gene expression patterns in Th17 cells from overweight patients with RA showed the characteristics of pathogenic Th17 cells.

Conclusions

Quantitative and qualitative changes in Th17 cells were characteristic in overweight patients with RA.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1308-y) contains supplementary material, which is available to authorized users.

Serum levels of adiponectin and leptin in asthmatic patients and its relation with asthma severity, lung function and BMI

INTRODUCTION

Asthma is one of the diseases which has a high prevalence in developed and developing countries. The relationship between asthma and obesity has always been focused by researchers. In this field, adipokines, especially adiponectin and leptin have highly attended by the scientist. The aim of this study was to determine the serum level of adiponectin, leptin and the leptin/adiponectin ratio in asthmatic patients and its relationship with disease severity, lung function and BMI (body mass index).

METHODS

In this cross-sectional study, 90 asthmatic women admitted to the tertiary referral hospital in Kurdistan province - Iran, were examined. First, BMI was measured and then pulmonary function tests were performed in all asthmatics patient. Forced expiratory volume in 1s (FEV1), forced vital capacity (FVC), and FEV1/FVC, were measured. At the end, blood samples were collected and serum level of adiponectin and leptin were measured by ELISA method.

RESULT

Serum leptin and leptin/adiponectin levels correlated positively with asthma severity and BMI (p=0.0001), but there was no correlation between adiponectin level with asthma severity and BMI (p>0.05), also serum leptin and leptin/adiponectin levels inversely correlated with FEV1 and FVC in patient (p=0.0001).

CONCLUSION

Asthma is linked with obesity, and there is an association between asthma severity and BMI with serum leptin and leptin/adiponectin levels, but our results do not support a significant role of adiponectin in obesity or asthma.

Leptin levels in patients with systemic lupus erythematosus inversely correlate with regulatory T cell frequency

Leptin levels are increased in patients with systemic lupus erythematosus (SLE) but little is known on how this correlates with several disease characteristics including the frequency of regulatory T cells (Tregs). Here we compared serum leptin levels with frequency of circulating Tregs in 47 lupus patients vs. 25 healthy matched controls. Correlations with lupus disease activity were also analyzed, as well as Treg proliferation potential. It was found that leptin was remarkably increased in SLE patients as compared to controls, particularly in SLE patients with moderate and severe active SLE, and the increase correlated with disease activity. Importantly, increased leptin in lupus patients inversely correlated with the frequency of Tregs but not in controls, and leptin neutralization resulted in the expansion of Tregs ex vivo. Thus, hyperleptinemia in lupus patients correlates directly with disease activity and inversely with Treg frequency. The finding that leptin inhibition expands Tregs in SLE suggests possible inhibition of this molecule for an enhanced Treg function in the disease.

Presence of IL-17 in synovial fluid identifies a potential inflammatory osteoarthritic phenotype

Purpose

Osteoarthritis (OA) is a common and heterogeneous arthritic disorder. Patients suffer pain and their joints are characterized by articular cartilage loss and osteophyte formation. Risk factors for OA include age and obesity with inflammation identified as a key mediator of disease pathogenesis. Interleukin-17A (IL-17) is a pro-inflammatory cytokine that has been implicated in inflammatory diseases such as rheumatoid arthritis. IL-17 can upregulate expression of inflammatory cytokines and adipocytokines. The aim of this study was to evaluate IL-17 levels in the synovial fluid of patients with end-stage knee and hip OA in relation to inflammation- and pain-related cytokines and adipocytokines in synovial fluid and serum, and clinical and radiographic disease parameters.

Methods

This is a cross-sectional study of 152 patients undergoing total hip and knee arthroplasty for OA. IL-17, IL-6, leptin, adiponectin, visfatin, resistin, C-C Motif Chemokine Ligand 2 (CCL2), C-C Motif Chemokine Ligand 7 (CCL7) and nerve growth factor (NGF) protein levels were measured in synovial fluid and serum using enzyme-linked immunosorbent assay (ELISA). Baseline characteristics included age, sex, body mass index, co-morbidities, pain and function, and radiographic analyses (OA features, K&L grade, minimal joint space width).

Results

14 patients (9.2%) had detectable IL-17 in synovial fluid. These patients had significantly higher median concentrations of IL-6, leptin, resistin, CCL7 and NGF. Osteophytes, sclerosis and minimum joint space width were significantly reduced in patients with detectable IL-17 in synovial fluid. No differences were found in pain, function and comorbidities. IL-17 concentrations in synovial fluid and serum were moderately correlated (r = 0.482).

Conclusion

The presence of IL-17 in the synovial fluid therefore identifies a substantial subset of primary end-stage OA patients with distinct biological and clinical features. Stratification of patients on the basis of IL-17 may identify those responsive to therapeutic targeting.

Leptin in the interplay of inflammation, metabolism and immune system disorders

Leptin is one of the most relevant factors secreted by adipose tissue and the forerunner of a class of molecules collectively called adipokines. Initially discovered in 1994, its crucial role as a central regulator in energy homeostasis has been largely described during the past 20 years. Once secreted into the circulation, leptin reaches the central and peripheral nervous systems and acts by binding and activating the long form of leptin receptor (LEPR), regulating appetite and food intake, bone mass, basal metabolism, reproductive function and insulin secretion, among other processes. Research on the regulation of different adipose tissues has provided important insights into the intricate network that links nutrition, metabolism and immune homeostasis. The neuroendocrine and immune systems communicate bi-directionally through common ligands and receptors during stress responses and inflammation, and control cellular immune responses in several pathological situations including immune-inflammatory rheumatic diseases. This Review discusses the latest findings regarding the role of leptin in the immune system and metabolism, with particular emphasis on its effect on autoimmune and/or inflammatory rheumatic diseases, such as rheumatoid arthritis and osteoarthritis.

Multiple Sclerosis and Obesity: Possible Roles of Adipokines

Multiple Sclerosis (MS) is an autoimmune disorder of the Central Nervous System that has been associated with several environmental factors, such as diet and obesity. The possible link between MS and obesity has become more interesting in recent years since the discovery of the remarkable properties of adipose tissue. Once MS is initiated, obesity can contribute to increased disease severity by negatively influencing disease progress and treatment response, but, also, obesity in early life is highly relevant as a susceptibility factor and causally related risk for late MS development. The aim of this review was to discuss recent evidence about the link between obesity, as a chronic inflammatory state, and the pathogenesis of MS as a chronic autoimmune and inflammatory disease. First, we describe the main cells involved in MS pathogenesis, both from neural tissue and from the immune system, and including a new participant, the adipocyte, focusing on their roles in MS. Second, we concentrate on the role of several adipokines that are able to participate in the mediation of the immune response in MS and on the possible cross talk between the latter. Finally, we explore recent therapy that involves the transplantation of adipocyte precursor cells for the treatment of MS.

Smoking Functions as a Negative Regulator of IGF1 and Impairs Adipokine Network in Patients with Rheumatoid Arthritis

Objectives. Smoking is pathogenic for rheumatoid arthritis (RA) being tightly connected to the genetic and serological risk factors for this disease. This study aims to understand connections between cigarette smoking and serum levels of IGF1 and adipokines in RA. Methods. Serum levels of IGF1 and adipokines leptin, adiponectin, resistin, and visfatin were measured in two independent cohorts of RA patients from Gothenburg (n = 350) and Leiden (n = 193). An association of these parameters with smoking was tested in a direct comparison and proved by bivariate correlation analysis. The obtained associations were further tested in multivariate regression models where the confounders (age, gender, disease duration, and BMI) were controlled. Results. The smokers had significantly lower serum levels of IGF1, adiponectin, and leptin compared to never smokers. In regression analysis, smoking and low leptin, but not adiponectin, were associated and predicted low IGF1. Additionally, high disease activity and high BMI increased the probability of low leptin. Conclusions. The study indicates cigarette smoking as an important cause of a relative IGF1 and leptin deficiency in RA patients. This novel association between smoking and hypoleptinemia may be of importance for long-term prognosis of RA and for prediction of comorbidities.