14-3-3η Protein in serum and synovial fluid correlates with radiographic damage and progression in a longitudinal evaluation of patients with established rheumatoid arthritis

Versatility of 14-3-3 proteins and their roles in bone and joint-related diseases

Bone and joint-related diseases, including osteoarthritis (OA), rheumatoid arthritis (RA), and bone tumors, pose significant health challenges due to their debilitating effects on the musculoskeletal system. 14-3-3 proteins, a family of conserved regulatory molecules, play a critical role in the pathology of these diseases. This review discusses the intricate structure and multifunctionality of 14-3-3 proteins, their regulation of signaling pathways, and their interactions with other proteins. We underscore the significance of 14-3-3 proteins in the regulation of osteoblasts, osteoclasts, chondrocytes, and bone remodeling, all key factors in the maintenance and dysfunction of bone and joint systems. Specific focus is directed toward elucidating the contribution of 14-3-3 proteins in the pathology of OA, RA, and bone malignancies, where dysregulated 14-3-3-mediated signaling cascades have been implicated in the disease processes. This review illuminates how the perturbation of 14-3-3 protein interactions can lead to the pathological manifestations observed in these disorders, including joint destruction and osteolytic activity. We highlight cutting-edge research that positions 14-3-3 proteins as potential biomarkers for disease progression and as innovative therapeutic targets, offering new avenues for disease intervention and management.

Serum 14‑3‑3η levels are increased and associated with a higher risk of osteoporosis in patients with rheumatoid arthritis: A meta‑analysis

14-3-3η can regulate the cell cycle, immunity, inflammation and the secretion of matrix metalloproteinases, while it may also be involved in the development of rheumatoid arthritis (RA) and promote bone injury. Therefore, the present meta-analysis focused on the dysregulated serum levels of 14-3-3η and its association with osteoporosis in patients with RA. Studies comparing the serum levels of 14-3-3η between patients with RA and healthy controls (HCs) or patients with RA with different bone mineral densities were retrieved from the EMBASE, Web of Science, PubMed and Cochrane databases. A total of 14 studies comprising 2,164 patients with RA and 1,136 HCs were included and analysed. Pooled analyses showed that the serum levels of 14-3-3η were enhanced in patients with RA compared with HCs [standardized mean difference (SMD): 1.34; 95% confidence interval (CI): 1.01-1.66; P<0.001]. In addition, the serum levels of 14-3-3η were also significantly higher in patients with RA with osteoporosis and osteopenia compared with those with normal bone mass (SMD: 1.96; 95% CI: 0.01-3.92; P=0.049 and SMD: 0.80; 95% CI: 0.09-1.52; P=0.028, respectively). Begg's and Egger's tests demonstrated that the publication bias for each evaluated indicator was low (all P>0.05). However, sensitivity analyses revealed that the findings were not very robust, which may be due to the omission of several individual studies. Overall, the present meta-analysis suggested that the serum levels of 14-3-3η were elevated and were associated with a higher risk of osteoporosis in patients with RA, thus supporting its potency as a circulating biomarker in the management of RA.

Scaffold Proteins in Autoimmune Disorders

Cells transmit information to the external environment and within themselves through signaling molecules that modulate cellular activities. Aberrant cell signaling disturbs cellular homeostasis causing a number of different diseases, including autoimmunity. Scaffold proteins, as the name suggests, serve as the anchor for binding and stabilizing signaling proteins at a particular locale, allowing both intra and intercellular signal amplification and effective signal transmission. Scaffold proteins play a critical role in the functioning of tight junctions present at the intersection of two cells. In addition, they also participate in cleavage formation during cytokinesis, and in the organization of neural synapses, and modulate receptor management outcomes. In autoimmune settings such as lupus, scaffold proteins can lower the cell activation threshold resulting in uncontrolled signaling and hyperactivity. Scaffold proteins, through their binding domains, mediate protein- protein interaction and play numerous roles in cellular communication and homeostasis. This review presents an overview of scaffold proteins, their influence on the different signaling pathways, and their role in the pathogenesis of autoimmune and auto inflammatory diseases. Since these proteins participate in many roles and interact with several other signaling pathways, it is necessary to gain a thorough understanding of these proteins and their nuances to facilitate effective target identification and therapeutic design for the treatment of autoimmune disorders.

Does Eta Protein Differentiate Rheumatoid Arthritis from Psoriatic Arthritis?

AIM

The clinical symptoms and laboratory markers of Rheumatoid Arthritis (RA) and Psoriatic Arthritis (PsA) can be very similar, so making a differential diagnosis between these two diseases is often difficult. Serological parameters to be used in differential diagnosis can guide the clinician. This study aimed to investigate the usability of 14-3-3η (eta) protein as a biomarker in the differential diagnosis of PsA and RA, and the relationships between eta protein and disease activity scores and joint erosions in PsA and RA.

METHODS

54 PsA patients, 53 RA patients, and 56 healthy individuals were included in this study. The ELISA (Enzyme-Linked ImunoSorbent Assay) kit was used as a quantitative sandwich enzyme immunoassay technique to detect human eta protein levels. Receiver- operating Characteristic (ROC) curves analysis was used to determine the sensitivity and specificity of the eta protein.

RESULTS

Eta protein levels were found to be significantly higher in the RA group than in the PsA [B: -0.341, OR (95% CI): 0.711 (0.556-0.909), p: 0.007] and control [B: -0.225, OR (95% CI): 0.798 (0.641-0.995), p: 0.045] groups. Eta protein median values were significantly higher in patients with joint erosion than in those without [β= 0.151, OR (95% CI): 1.163 (1.003-1.349), p: 0.046].

CONCLUSION

Eta protein levels are higher in the serum of RA patients than PsA and are associated with joint erosion. Eta protein may be a potential biomarker in the differential diagnosis of RA and PsA. It may represent a possible therapeutic step in the pathophysiological pathways in the development of joint erosion.

14-3-3η Proteins as a Diagnostic Marker, Disease Activation Indicator, and Lymphoma Predictor in Patients with Primary Sjögren Syndrome

BACKGROUND

Primary Sjögren syndrome (PSS) is a chronic, autoimmune, and lymphoproliferative disease of the connective tissue. In patients with PSS, the risk of developing B-cell non-Hodgkin lymphoma (NHL) increases dramatically, with a prevalence of approximately 5%. The 14-3-3 protein isoforms are phospho-serin/phospho-threonine binding proteins associated with many malignant diseases. This study aimed to evaluate the relationship between disease activity parameters and markers predicting lymphoma development in patients with PSS and 14-3-3η proteins.

METHODS

This study was designed as an analytical case-control study. A total of 57 PSS patients and 54 healthy volunteers were included in the study. The European League Against Rheumatism (EULAR) Sjögren syndrome disease activity index (ESSDAI) was used to assess systemic disease activity in PSS. Receiver operating characteristic (ROC) analysis was used to test the diagnostic accuracy measures of the analytical results. Multivariable linear regression analysis was used to evaluate the effects of independent variables on the 14-3-3η protein.

RESULTS

The 14-3-3η protein serum levels were found to be significantly higher in PSS (2.72 [2.04-4.07]) than healthy controls (1.73 [1.41-2.43]) (P<0.0001). A significant relationship was found between 14-3-3η protein levels and ESSDAI group (β=0.385, 95%CI=0.318-1.651, P=0.005), hypocomplementemia (C3 or C4) (β=0.223, 95% CI=0.09-1.983, P=0.048) and purpura (β=0.252, 95% CI=0.335-4.903, P=0.022), which are accepted as lymphoma predictors. A significant correlation was found between PSS disease activity score ESSDAI and 14-33η protein (β=0.496, 95% CI=0.079-0.244, P=0.0002).

CONCLUSION

14-3-3η proteins are potential candidates for diagnostic marker, marker of disease activity, and predictor of lymphoma in PSS patients.

14-3-3η Promotes Invadosome Formation via the FOXO3-Snail Axis in Rheumatoid Arthritis Fibroblast-like Synoviocytes

Erosive destruction of joint structures is a critical event in the progression of rheumatoid arthritis (RA), in which fibroblast-like synoviocytes (FLS) are the primary effectors. We previously reported that the ability of RA FLS to degrade extracellular matrix (ECM) components depends on the formation of actin-rich membrane protrusions, called invadosomes, through processes that remain elusive. 14-3-3η belongs to a family of scaffolding proteins involved in a wide range of cellular functions, and its expression is closely related to joint damage and disease activity in RA patients. In this study, we sought to assess the role of 14-3-3η in joint damage by examining its contribution to the invadosome formation phenotype of FLS. Using human primary FLS, we show that 14-3-3η expression is closely associated with their ability to form invadosomes. Furthermore, knockdown of 14-3-3η using shRNAs decreases the level of invadosome formation in RA FLS, whereas addition of the recombinant protein to FLS from healthy individuals promotes their formation. Mechanistic studies suggest that 14-3-3η regulates invadosome formation by increasing Snail expression, a mechanism that involves nuclear exclusion of the transcription repressor FOXO3. Our results implicate the 14-3-3η–FOXO3–Snail axis in promoting the aggressive ECM-degrading phenotype of RA FLS, and suggest a role for this scaffolding protein in cartilage degradation.

The significance of serum 14-3-3η level in rheumatoid arthritis patients

BACKGROUND

RA is a systemic inflammatory condition characterized by chronic arthritis and often associated with irreversible joint damage.

OBJECTIVES

To assess the significance of serum level of 14-3-3η in RA and its association with clinical and serological features of the disease.

METHODS

This is a case-control study done on 80 participants. They were divided into 2 groups. Group 1: 40 rheumatoid arthritis patients compared to group 2: 40 healthy participants matched for age and sex. Laboratory investigations including complete blood count (CBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) rheumatoid factor (RF), anti-citrullinated peptide antibodies (ACPAs), and serum 14-3-3η were done to all participants. Radiological examination in the form of plain X-ray for hands and feet was done to all patients.

RESULTS

Serum levels of 14-3-3η were significantly higher in RA patients compared to the control group (p < 0.001). Serum 14-3-3η was the only predictor of high Larsen's score (p = 0.013) on using linear regression analysis. Serum 14-3-3η can predict RA in healthy controls in univariate (p = 0.001) and multivariate (p = 0.004) analyses. The receiver operating characteristic (ROC) curve of 14-3-3η was constructed for discrimination between RA and control subjects. The best cut-off value was 61.9 ng/mL, with fair AUC (0.773, p < 0.001), 95% CI (0.656-0.889), and the sensitivity and specificity of 14-3-3η for RA diagnosis as 65% and 95% respectively. Also, we constructed ROC curves for RF, ACPA, 14-3-3η, and their combinations; we found that the highest test sensitivity of 95.7% appeared on adding the 3 markers together, and the highest test specificity of 100% was detected on adding RF to ACPA, 14-3-3η to ACPA or the 3 molecules together.

CONCLUSION

14-3-3η could be a valuable marker for the diagnosis of RA patients and it may have prognostic value. Key Points • 14-3-3η is a valuable marker for the diagnosis of RA patients. • 14-3-3η reflects disease severity and joint damage in RA patients.

Serum 14-3-3η is a Marker that Complements Current Biomarkers for the Diagnosis of RA: Evidence from a Meta-analysis

OBJECTIVE

To systematically evaluate the diagnostic value of 14-3-3η protein for rheumatoid arthritis (RA).

METHOD

Searched PubMed, Web of Science, Embase and China Biology Medicine (CBM) databases comprehensively from inception to May 2020. The evaluation index were the pooled sensitivity, specificity, diagnosis odds ratio (DOR), positive likelihood ratio (PLR), negative likelihood ratio (NLR), as well as the area under the summary receiver operating characteristic (SROC) curves. Meta-Disc 1.4 and RevMan 5.3 were used to analyze all statistics. QUADAS-2 tool was applied to evaluate the quality of eligible studies. Subgroup analysis and meta-regression were used to explore the sources of heterogeneity.

RESULTS

Nine articles containing eleven records were eligible for this meta-analysis. The pooled sensitivity of 14-3-3η was 0.63 (95% CI: 0.60 to 0.66), the pooled specificity was 0.90 (95% CI: 0.88 to 0.91). The pooled PLR and NLR was 6.10 (95% CI: 4.67 to 7.96) and 0.40 (95% CI: 0.33 to 0.48), respectively. The pooled DOR was 15.90 (95% CI: 11.15 to 22.68), and the area under the curve (AUC) was 0.8696. Compared with a single indicator (rheumatoid factor or anti-citrullinated protein antibodies), adding 14-3-3η can bring incremental benefits to the diagnosis of RA. The results of subgroup analysis and meta-regression suggested that the two factors (ethnicity, early vs established RA) we analyzed might not be the source of heterogeneity (P value were 0.0979 and 0.4298, respectively) and there was no publication bias among these articles (P = .42).

CONCLUSION

Serum 14-3-3η protein is a supplementary biomarker in the diagnosis of RA.