Nutrients and rheumatoid arthritis: From the perspective of neutrophils

Iron, copper, zinc and magnesium on rheumatoid arthritis: a two-sample Mendelian randomization study

This study aimed to elucidate the causal genetic relationships between iron, copper, zinc, magnesium, and rheumatoid arthritis (RA). A two-sample Mendelian randomization (MR) analysis was conducted using the "TwoSampleMR" and "MendelianRandomization" packages in R. The random-effects inverse variance-weighted (IVW) method was used as the primary approach. We performed sensitivity analyses to test the reliability of the results. The random-effects IVW analysis revealed that there was no genetic causal relationship between iron (P = 0.429, odds ratio [OR] 95% confidence interval [CI] = 0.919 [0.746-1.133]), copper (P = 0.313, OR 95% CI = 0.973 [0.921-1.027]), zinc (P = 0.633, OR 95% CI = 0.978 [0.891-1.073]), or magnesium (P = 0.218, OR 95% CI = 0.792 [0.546-1.148]) and RA. Sensitivity analysis verified the reliability of the results. Therefore, there is no evidence to support a causal relationship between iron, copper, zinc, and magnesium intake at the genetic level and the development of RA.

Association of dietary inflammatory index with immune-inflammatory biomarkers in rheumatoid arthritis patients: results from NHANES 1999-2018

Background

Synovial inflammation is the main reason for joint damage in patients with rheumatoid arthritis (RA). Diet is recognized as one of the therapeutic strategies to control the inflammatory activity in RA. However, few studies have investigated the association between diet and immune-inflammatory biomarkers in RA patients. Our study aims to examine the correlation between dietary inflammatory potential and systemic immune-inflammation Index (SII), neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), and lymphocyte-monocyte ratio (LMR) in the RA population.

Materials and methods

The National Health and Nutrition Examination Survey (NHANES) was the data source utilized in this study, spanning from 1999 to 2018. The study encompassed 2,500 RA participants in total. The dietary inflammatory potential was calculated by the dietary inflammation index (DII) score based on dietary recall interviews. The generalized multiple linear regression analyses were used to evaluate the relationship between DII and immune-inflammatory markers. Furthermore, subgroup analyses and restricted cubic spline models were performed.

Results

After full adjustments, there were significant positive correlations between DII levels and SII/NLR in RA patients (SII, β: 14.82, 95% CI: 5.14-24.50, p = 0.003; NLR, β: 0.04, 95% CI: 0.01-0.08, p = 0.005). It was noteworthy that inconsistent results were observed in the association between DII and SII as well as NLR in subgroups of red blood cell levels (Interaction p-value <0.001).

Conclusion

Pro-inflammatory dietary status in the RA population is significantly positively correlated with SII and NLR, influenced by variations in red blood cell levels.

The levels of IL1RN is a factor influencing the onset of rheumatoid arthritis in non-alcoholic fatty liver disease

With the improvement of global dietary conditions, non-alcoholic fatty liver disease (NAFLD) has gradually become prevalent. As the number of NAFLD patients increases, the coexistence of diseases associated with it has come into focus. In this study, based on immune phenotypes, intercellular communication activities, and clinical manifestations of NAFLD patients, IL1RN was identified as a central pro-inflammatory factor. Subsequently, potential downstream biological pathways of IL1RN in liver tissues and various cell types were enriched to describe its functions. Transcription factors Nfkb1, Jun, and Sp1, significantly associated with these functions, were also enriched. Functional studies of IL1RN suggest its potential to trigger autoimmune diseases. Given this, Mendelian randomization analysis was used to explore the causal relationship between NAFLD and various autoimmune diseases, with IL1RN considered as an intermediary introduced into Mendelian randomization studies. The results indicate that IL1RN and its partially related proteins play a certain mediating role in the process of NAFLD inducing rheumatoid arthritis (RA). Finally, additional research results suggest that intrahepatic ALT levels may influence IL1RN levels, possibly through amino acid metabolism.

Celastrol-loaded bovine serum albumin nanoparticles target inflamed neutrophils for improved rheumatoid arthritis therapy

Inflammatory neutrophils (INEs), motivated by cytokines, continue to migrate into the inflamed joints, driving the development of RA. Hence, inducing apoptosis of INEs to reduce recruitment at inflamed joints is an effective strategy for the treatment of RA. However, simply apoptotic INEs may trigger the release of neutrophil extracellular traps (NETs) and accelerate the inflammatory process. To overcome these drawbacks, an RGD-modified bovine serum albumin (BSA) nanoparticles (CBR NPs) was fabricated to selectively target INEs in situ for intracellular delivery of CLT. Studies have demonstrated that CBR NPs can selectively target circulating INEs and induce INEs apoptosis. Meanwhile, CBR NPs inhibited the activation of NETs via NF-κB pathway and the release of Cit-H3 thereby blocking the release process of NETs. In collagen-induced arthritis (CIA) mouse model, CBR NPs suppressed the inflammatory response, and reduced the toxic effects of CLT. In summary, this study shed light on an innovative approach to treat RA by inducing apoptosis of circulating INEs and inhibiting NETs. STATEMENT OF SIGNIFICANCE: RGD-modified bovine serum albumin (BSA) nanoparticles for delivering celastrol, abbreviated as CBR NPs, were constructed to inhibit the infiltration of circulating inflammatory neutrophils (INEs) into inflamed joints while inhibiting the release of NETs to alleviate tissue damage. CBR NPs were prepared for the first time to induce apoptosis of INEs; CBR NPs could inhibit the release of NETs while inducing apoptosis of INEs in vivo and vitro cellular experiments; CBR NPs had favorable anti-inflammatory effects and low toxicity side-effects in collagen-induced arthritis (CIA) mouse models. The application of nanotechnology to induce apoptosis of INEs while inhibiting the release of NETs was a promising approach for the treatment of RA.

A metabolic perspective of the neutrophil life cycle: new avenues in immunometabolism

Neutrophils are the most abundant innate immune cells. Multiple mechanisms allow them to engage a wide range of metabolic pathways for biosynthesis and bioenergetics for mediating biological processes such as development in the bone marrow and antimicrobial activity such as ROS production and NET formation, inflammation and tissue repair. We first discuss recent work on neutrophil development and functions and the metabolic processes to regulate granulopoiesis, neutrophil migration and trafficking as well as effector functions. We then discuss metabolic syndromes with impaired neutrophil functions that are influenced by genetic and environmental factors of nutrient availability and usage. Here, we particularly focus on the role of specific macronutrients, such as glucose, fatty acids, and protein, as well as micronutrients such as vitamin B3, in regulating neutrophil biology and how this regulation impacts host health. A special section of this review primarily discusses that the ways nutrient deficiencies could impact neutrophil biology and increase infection susceptibility. We emphasize biochemical approaches to explore neutrophil metabolism in relation to development and functions. Lastly, we discuss opportunities and challenges to neutrophil-centered therapeutic approaches in immune-driven diseases and highlight unanswered questions to guide future discoveries.