Nicotinamide Phosphoribosyltransferase Attenuates Methotrexate Response in Juvenile Idiopathic Arthritis and In Vitro

Biochemical and genomic identification of novel biomarkers in progressive sarcoidosis: HBEGF, eNAMPT, and ANG-2

Background

Progressive pulmonary fibrosis is a serious complication in subjects with sarcoidosis. The absence of reliable, non-invasive biomarkers that detect early progression exacerbates the difficulty in predicting sarcoidosis severity. To potentially address this unmet need, we evaluated a panel of markers for an association with sarcoidosis progression (HBEGF, NAMPT, IL1-RA, IL-6, IL-8, ANG-2). This panel encompasses proteins related to inflammation, vascular injury, cell proliferation, and fibroblast mitogenesis processes.

Methods

Plasma biomarker levels and biomarker protein expression in lung and lymph nodes tissues (immunohistochemical studies) from sarcoidosis subjects with limited disease and progressive (complicated) sarcoidosis were performed. Gene expression of the protein-coding genes included in this panel was analyzed using RNAseq in sarcoidosis granulomatous tissues from lung and lymph nodes.

Results

Except for IL-8, plasma levels of each biomarker—eNAMPT, IL-1RA, IL-6, ANG-2, and HBEGF—were significantly elevated in sarcoidosis subjects compared to controls. In addition, plasma levels of HBEGF were elevated in complicated sarcoidosis, while eNAMPT and ANG-2 were observed to serve as markers of lung fibrosis in a subgroup of complicated sarcoidosis. Genomic studies corroborated HBEGF and NAMPT among the top dysregulated genes and identified cytokine-related and fibrotic pathways in lung granulomatous tissues from sarcoidosis.

Conclusion

These findings suggest HBEGF, eNAMPT, and ANG-2 may serve as potential novel indicators of the clinical severity of sarcoidosis disease.

Responses of patients with juvenile idiopathic arthritis to methotrexate: a genomic outlook

INTRODUCTION

Juvenile idiopathic arthritis (JIA) is a chronic disease characterized by persistent joint inflammation. JIA is the most common pediatric chronic rheumatic disease and no curative therapy is currently available. Methotrexate (MTX) is an important treatment for JIA even though a high inter-individual variability in response is observed in patients. Among the factors of this variability, genetics and epigenetics might play an important role.

AREAS COVERED

This review summarizes the results of pharmacogenetic and pharmacoepigenetic studies regarding MTX response in JIA. Studies considering epigenetic factors in JIA patients are still very limited, therefore this review includes also studies performed in adult patients with rheumatoid arthritis. Moreover, the relevance of biomarkers measured in blood or urine of JIA patients in relation to MTX treatment is discussed.

EXPERT OPINION

Nowadays, even though many pharmacogenomics studies have been published, a specific genetic marker predictor of MTX efficacy or adverse events has not yet been identified. Encouraging results are available and great expectations rely on the study of epigenetics. Future studies are needed in order to identify genetic and epigenetic biomarkers that can be implemented in the clinical practice.

Adipokine role in physiopathology of inflammatory and degenerative musculoskeletal diseases

We performed a systematic literature review to summarize the underlying pathogenic mechanisms by which adipokines influence rheumatological diseases and the resulting clinical manifestations. Increasing evidence display that numerous adipokines may significantly influence the development or clinical course of various rheumatological diseases. Despite the normal anti- or pro-inflammatory role of the cytokines, the serum level varies enormously in various rheumatological diseases. The expression of high levels of pro-inflammatory cytokines such as leptin or visfatin, respectively in systemic lupus erythematosus and in rheumatoid arthritis, represents a negative prognostic factor; other adipokines such as adiponectin, broadly known for their anti-inflammatory effects, showed a correlation with disease activity in rheumatoid arthritis. In the near future pro-inflammatory cytokines may represent a potential therapeutic target to restrain the severity of rheumatological diseases. Further studies on adipokines may provide important information on the pathogenesis of these diseases, which are not yet fully understood. The mechanisms by which adipokines induce, worsen, or suppress inflammatory and degenerative musculoskeletal pathologies and their clinical significance will be discussed in this review.

Protective effect of benfotiamine on methotrexate induced gastric damage in rats

Methotrexate (MTX) is widely used for treating cancers and inflammatory diseases; it is a potential anti-metabolite and folate antagonist. We investigated potential protective effects of benfotiamine on MTX damage. We used a rat model of MTX induced gastric injury to assess changes in gastric histopathology, oxidative stress and visfatin levels due to MTX treatment. Rats were divided into four groups: an untreated control group, an MTX group treated with a single dose of MTX, a benfotiamine group treated with benfotiamine daily for two weeks, and a benfotiamine + MTX group treated with a single dose of MTX followed by benfotiamine daily for two weeks. Total tissue antioxidant status (TAS), total oxidant status (TOS) and visfatin levels were measured at the end of the experiment. At the end of the experiment, we investigated both visfatin expression and the histopathology of gastric tissues. The mean visfatin level was lower in the MTX group than in the benfotiamine group. The mean tissue TOS levels were higher in MTX group than in the control, benfotiamine or benfotiamine + MTX groups. Significant gastric gland dilation, and erosion and loss of mucosa were found on the gastric surface in the MTX group compared to the control group. The dilation, erosion and mucosal loss were decreased significantly in the benfotiamine + MTX group compared to the MTX group. Compared to the control group, visfatin immunoreactivity was reduced significantly in the MTX group. Decreased visfatin levels appear to play a role in the mechanism of gastric damage. Benfotiamine may be useful for preventing MTX induced gastric injuries.

Subclinical cardiovascular risk signs in adults with juvenile idiopathic arthritis in sustained remission

BACKGROUND

Juvenile Idiopathic Arthritis (JIA) is one of the most common chronic diseases of childhood that often persists into adulthood and can result in significant long-term morbidity. As a long lasting chronic inflammatory disease, concern has been raised regarding the risk of premature development of cardiovascular disease (CVD) in JIA. This study aims to determine whether adults with JIA in clinical remission display clinical and subclinical signs of CVD risk: inflammatory mediators, adipokines, endothelial dysfunction and oxidative stress markers.

METHODS

This is a cross-sectional study including 25 patients diagnosed with JIA according to the International League of Associations for Rheumatology criteria (ILAR 2001) and 25 age- and sex-matched controls. Remission was determined by JADAS10 < 1 and according to Wallace criteria. The presence of traditional CVD risk factors was analyzed. An extensive clinical analysis including body mass index (BMI), lipid profile, homeostatic model assessment - insulin resistance (HOMA-IR) and arterial blood pressure was performed. Intima media thickness of the common carotid artery (CIMT) was measured as a marker of subclinical atherosclerosis. Several proinflammatory cytokines, molecules involved in the endothelial dysfunction, oxidative stress and adipokines were quantified on serum by ELISA and on peripheral blood mononuclear cells (PBMCs) by RT-PCR. In vitro studies were carried out in healthy PBMCs, adipocytes and endothelial cells which were treated with serum from JIA patients under sustained remission.

RESULTS

Mean duration of the disease was 13.47 ± 5.47 years. Mean age was 25.11 ± 7.21. Time in remission was 3.52 ± 3.33 years. Patients were in remission with no treatment (40%) and with treatments (60%). CVD risk factors and CIMT were similar in JIA patients and controls. However, cholesterol levels were significantly elevated in JIA patients. Levels of adipocytokines, oxidative stress and endothelial activation markers were elevated in serum and PBMCs from JIA patients. Serum of those JIA patients induced the activation of adipocytes, endothelial cells and healthy PBMCs.

CONCLUSIONS

JIA adult patients in remission have subclinical signs of inflammation and CVD risk, showed by an increase in the levels of inflammatory cytokines, endothelial activation and oxidative stress markers and adipokines, molecules closely involved in the alteration of the vascular system.

Epigenetic regulation of NfatC1 transcription and osteoclastogenesis by nicotinamide phosphoribosyl transferase in the pathogenesis of arthritis

Nicotinamide phosphoribosyltransferase (NAMPT) functions in NAD synthesis, apoptosis, and inflammation. Dysregulation of NAMPT has been associated with several inflammatory diseases, including rheumatoid arthritis (RA). The purpose of this study was to investigate NAMPT’s role in arthritis using mouse and cellular models. Collagen-induced arthritis (CIA) in DBA/1J Nampt^+/− mice was evaluated by ELISA, micro-CT, and RNA-sequencing (RNA-seq). In vitro Nampt loss-of-function and gain-of-function studies on osteoclastogenesis were examined by TRAP staining, nascent RNA capture, luciferase reporter assays, and ChIP-PCR. Nampt-deficient mice presented with suppressed inflammatory bone destruction and disease progression in a CIA mouse model. Nampt expression was required for the epigenetic regulation of the Nfatc1 promoter and osteoclastogenesis. Finally, RNA-seq identified 690 differentially expressed genes in whole ankle joints which associated (P < 0.05) with Nampt expression and CIA. Selected target was validated by RT-PCR or functional characterization. We have provided evidence that NAMPT functions as a genetic risk factor and a potential therapeutic target to RA.

Nicotinamide Phosphoribosyltransferase Deficiency Potentiates the Antiproliferative Activity of Methotrexate through Enhanced Depletion of Intracellular ATP

Lower plasma nicotinamide phosphoribosyltransferase (NAMPT) levels are associated with improved response to methotrexate (MTX) in patients with juvenile idiopathic arthritis. Cell-based studies confirmed that reduced cellular NAMPT activity potentiates the pharmacologic activity of MTX; however, the mechanism of this interaction has yet to be defined. Therefore, in this study, we investigate the mechanism of enhanced pharmacologic activity of MTX in NAMPT-deficient A549 cells. Small interfering RNA-based silencing of NAMPT expression resulted in a greater than 3-fold increase in sensitivity to MTX (P < 0.005) that was completely reversed by supplementation with folinic acid. Despite a 68% reduction in cellular NAD levels in NAMPT-deficient cells, no change in expression or activity of dihydrofolate reductase was observed and uptake of MTX was not significantly altered. MTX did not potentiate the depletion of cellular NAD levels, but NAMPT-deficient cells had significant elevations in levels of intermediates of de novo purine biosynthesis and were 4-fold more sensitive to depletion of ATP by MTX (P < 0.005). Supplementation with hypoxanthine and thymidine completely reversed the antiproliferative activity of MTX in NAMPT-deficient cells and corresponded to repletion of the cellular ATP pool without any effect on NAD levels. Together, these findings demonstrate that increased MTX activity with decreased NAMPT expression is dependent on the antifolate activity of MTX and is driven by enhanced sensitivity to the ATP-depleting effects of MTX. For the first time, these findings provide mechanistic details to explain the increase in pharmacological activity of MTX under conditions of reduced NAMPT activity.

In the Pursuit of Methotrexate Treatment Response Biomarker in Juvenile Idiopathic Arthritis-Are We Getting Closer to Personalised Medicine?

PURPOSE OF REVIEW

Methotrexate (MTX) is the most widely used disease-modifying antirheumatic drug (DMARD) in paediatric rheumatology and the mainstay in the therapy of juvenile idiopathic arthritis (JIA). Despite its common use, about 30% of children fail to respond to this medicine that results in potentially irreversible joint damage.

RECENT FINDINGS

No clinical biomarker that would predict the outcome of MTX therapy exists. Results of several studies focused on gene polymorphisms and outcome of this DMARD therapy have been published, but no reliable genetic marker useful to tailor the therapy has been discovered so far. The results of the first genome-wide association study in this field have recently revealed new genetic candidates from outside the metabolic pathway of MTX that may be associated with the efficacy of treatment. However promising, those outcomes need validation in independent prospective cohorts before we can claim that clinically useful biomarker predicting MTX treatment response is discovered.

NAMPT serum levels are selectively elevated in acute infectious disease and in acute relapse of chronic inflammatory diseases in children

Nicotinamide phosphoribosyl transferase (NAMPT) is an inflammatory adipocytokine shown to interact in immune modulation in chronic inflammatory diseases, acute respiratory distress syndrome, sepsis, cancer and obesity in adulthood. It is, however, not clear whether this association reflects a chronic elevation or acute inflammatory response. We analyzed NAMPT concentrations in distinct states of inflammation in 102 children and found consistently significantly increased NAMPT levels in subjects with acute infections. NAMPT concentrations in children with stable chronic inflammatory diseases were not significantly different, whereas in patients with acute relapse of chronic disease NAMPT was significantly higher than in children in remission or healthy controls. In states of low-grade inflammation (children with atopic disease or obesity) we did not detect alterations in NAMPT serum levels. NAMPT correlated positively with inflammatory markers such as CRP. The most predictive factor for NAMPT serum concentrations was leucocyte count and therein the neutrophil count. Furthermore, systemic circulating NAMPT levels were closely associated with NAMPT release from corresponding cultured PBMCs. In conclusion, NAMPT is selectively increased in states of acute but not chronic inflammation in children. The close relationship between systemic circulating NAMPT with leucocyte counts and release indicate that leucocytes most probably are the source of inflammation related NAMPT levels.