Humoral Response to Microbial Biomarkers in Rheumatoid Arthritis Patients

Decoding the Microbiome's Influence on Rheumatoid Arthritis

The aim is better to understand and critically explore and present the available data from observational studies on the pathogenetic role of the microbiome in the development of rheumatoid arthritis (RA). The electronic databases PubMed, Scopus, and Web of Science were screened for the relevant literature published in the last ten years. The primary outcomes investigated included the influence of the gut microbiome on the pathogenesis and development of rheumatoid arthritis, exploring the changes in microbiota diversity and relative abundance of microbial taxa in individuals with RA and healthy controls (HCs). The risk of bias in the included literature was assessed using the GRADE criteria. Ten observational studies were identified and included in the qualitative assessment. A total of 647 individuals with RA were represented in the literature, in addition to 16 individuals with psoriatic arthritis (PsA) and 247 HCs. The biospecimens comprised fecal samples across all the included literature, with 16S rDNA sequencing representing the primary method of biological analyses. Significant differences were observed in the RA microbiome compared to that of HCs: a decrease in Faecalibacterium, Fusicatenibacter, Enterococcus, and Megamonas and increases in Eggerthellales, Collinsella, Prevotella copri, Klebsiella, Escherichia, Eisenbergiella, and Flavobacterium. There are significant alterations in the microbiome of individuals with RA compared to HCs. This includes an increase in Prevotella copri and Lactobacillus and reductions in Collinsella. Collectively, these alterations are proposed to induce inflammatory responses and degrade the integrity of the intestinal barrier; however, further studies are needed to confirm this relationship.

Dipeptidyl peptidase 4 as a potential serum biomarker for disease activity and treatment response in rheumatoid arthritis

BACKGROUND

The treatment of rheumatoid arthritis (RA) related to the disease activity. However, the lack of highly sensitive and simplified markers limits the evaluation of disease activity. We sought to explore potential biomarkers associated with disease activity and treatment response in RA.

METHODS

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteomic analysis was performed to determine the differentially expressed proteins (DEPs) in serum collected from RA patients with moderate or high disease activity (determined by DAS28) before and after 24 weeks of treatment. Bioinformatic analysis were performed for DEPs and hub proteins. In the validation cohort, 15 RA patients were enrolled. Key proteins were validated by enzyme-linked immunosorbent assay (Elisa), correlation analysis and ROC curve.

RESULTS

We identified 77 DEPs. The DEPs enriched in humoral immune response, blood microparticle, and serine-type peptidase activity. KEGG enrichment analysis displayed that the DEPs were significantly enriched in cholesterol metabolism and complement and coagulation cascades. Activated CD4 + T cell, T follicular helper cell, natural killer cell, and plasmacytoid dendritic cell significantly increased after treatment. Fifteen hub proteins were screened out. Among them, dipeptidyl peptidase 4 (DPP4) was the most significant protein associated with clinical indicators and immune cells. Serum concentration of DPP4 was testified to significantly increase after treatment and inversely correlate with disease activity indicators (ESR, CRP, DAS28-ESR, DAS28-CRP, CDAI, SDAI). Significant reduction was found in the serum CXC chemokine ligand10 (CXC10) and CXC chemokine receptor 3 (CXCR3) after treatment.

CONCLUSIONS

Overall, our results suggest that serum DPP4 might be a potential biomarker for disease activity assessment and treatment response of RA.

The Interaction Effect of Anti-RgpA and Anti-PPAD Antibody Titers: An Indicator for Rheumatoid Arthritis Diagnosis

Porphyromonas gingivalis secretes virulence factors like Arg-gingipains and peptidyl arginine deiminase (PPAD), that are associated with rheumatoid arthritis (RA) pathogenesis. However, there is no information regarding the antibody titers for these bacterial enzymes as systemic indicators or biomarkers in RA. In this cross-sectional study, 255 individuals were evaluated: 143 were diagnosed with RA, and 112 were without RA. Logistic regression models adjusted for age, sex, basal metabolic index, smoking, and periodontitis severity were used to evaluate the association of RA with rheumatoid factor (RF), anti-citrullinated protein antibodies (ACPAs), erythrocyte sedimentation rate, high sensitivity C-reactive protein, anti-RgpA, anti-PPAD, and double positive anti-RgpA/anti-PPAD. It was found that RF (odds ratio [OR] 10.6; 95% confidence interval [CI] 4.4-25), ACPAs (OR 13.7; 95% CI 5.1-35), and anti-RgpA/anti-PPAD double positivity (OR 6.63; 95% CI 1.61-27) were associated with RA diagnoses. Anti-RgpA was also associated with RA (OR 4.09; 95% CI 1.2-13.9). The combination of anti-RgpA/anti-PPAD showed a high specificity of 93.7% and 82.5% PPV in identifying individuals with RA. RgpA antibodies were associated with the periodontal inflammatory index in RA individuals (p < 0.05). The double positivity of the anti-RgpA/anti-PPAD antibodies enhanced the diagnosis of RA. Therefore, RgpA antibodies and anti-RgpA/anti-PPAD may be biomarkers for RA.

Antibodies against HSV-1 and Curli Show the Highest Correlation in Parkinson's Disease Patients in Comparison to Healthy Controls

Parkinson’s disease (PD) is a neurodegenerative disorder involving the accumulation of alpha-synuclein (α-syn)/Lewy bodies in the brain and -enteric nervous system. The etiology of the disease is not well understood, but bacterial and viral infections may contribute to the pathogenesis of PD. It has been suggested that the gastrointestinal (GI) complications observed in PD patients may arise from bacterial dysbiosis, leading to curli/α-syn deposits in the enteric nervous system. Enteric bacteria secrete curli, a functional amyloid peptide involved in adhesion to surfaces, cell invasion, and biofilm formation. However, these bacterial amyloids can initiate additional α-syn deposits through immune system activation and cross-seeding. In this study, we investigate the humoral response against α-syn, curli peptides, and various bacterial and viral immunogen peptides in PD patients, and compare them with those in healthy controls (HCs). Polyclonal IgG antibodies (Abs) were detected against peptides derived from α-syn (α-syn100−114), curli (Curli133−141), Porphyromonas gingivalis Pg (RgpA800−812, Kpg328−339), Aggregatibacter actinomycetemcomitans (LtxA1429−445, LtxA264−80), Mycobacterium avium subsp. paratuberculosis (MAP3865c125−133, MAP1,4-a-gbp157−173 and MAP_402718−32), Epstein−Barr virus (EBNA1400−413, BOLF1305−320), and Herpes Simplex virus 1 (UI4222−36), as investigated by indirect ELISA of 51 serum samples from PD and 58 sex and age-matched HCs. Significant differences in OD (optical density) values and Abs positivity between PD patients and HCs were observed for Kpg (82.3% vs. 10.3%), followed by RgpA (60.7% vs. 24.1%), curli (51% vs. 22.4%), and UI42 (43.1% vs. 25.8%) in PD, compared to HCs sera (p < 0.001). No significant difference was found in the ODs obtained from other tested peptides in PD patients, compared to HCs. Significant positive correlations between OD values obtained by ELISA were observed for UI42 and curli (r = 0.811, p < 0.0001), Kpg and RgpA (r = 0.659, p < 0.0001), followed by LtxA1 and LtxA2 (r = 0.653, p < 0.0001). The correlation between the HY scale (Hoehn and Yahr Scale) and LtxA1 (r = 0.306, p < 0.028) and HY and Kpg (r = 0.290, p < 0.038) were significantly positive. This study reports a significantly increased humoral response against curli, Pg, and HSV-1 in PD patients, implying that they could be important factors in the pathogenesis of the disease. In addition, the high positive correlation between UI42 and curli may suggest the involvement of HSV-1 in GI dysbiosis. Therefore, the role of each individual pathogen and curli in PD needs to be further investigated.

Human endogenous retroviruses and the inflammatory response: A vicious circle associated with health and illness

Human Endogenous Retroviruses (HERVs) are derived from ancient exogenous retroviral infections that have infected our ancestors' germline cells, underwent endogenization process, and were passed throughout the generations by retrotransposition and hereditary transmission. HERVs comprise 8% of the human genome and are critical for several physiological activities. Yet, HERVs reactivation is involved in pathological process as cancer and autoimmune diseases. In this review, we summarize the multiple aspects of HERVs' role within the human genome, as well as virological and molecular aspects, and their fusogenic property. We also discuss possibilities of how the HERVs are possibly transactivated and participate in modulating the inflammatory response in health conditions. An update on their role in several autoimmune, inflammatory, and aging-related diseases is also presented.

Purification of RgpA from external outer membrane vesicles of Porphyromonas gingivalis

INTRODUCTION

Purification of native gingipains is challenging because these proteases are frequently associated with the cell surface, which affects yield. This study aimed to purify native Arg-gingipain (RgpA) from Porphyromonas gingivalis Outer Membrane Vesicles (OMV).

METHODS

Native RgpA was purified from P. gingivalis strain ATCC33277 OMV using a strategy including ultracentrifugation, sonication, and successive anionic and cationic fast protein liquid chromatography (FPLC). The presence and purity of the protease were confirmed by SDS-PAGE and detection of protease activity using fluorogenic substrates. Rat antibodies produced against the unique adhesin hemagglutinin (H1) domain of RgpA (amino acids 719-865) were titrated by ELISA at a 1:100 dilution using whole P. gingivalis lysate as an antigen and western blotting to detect a 75 kDa band corresponding to RgpA.

RESULTS

Double anionic-cationic FLPC yielded prominent peaks with evident amidolytic gingipain activity of the appropriate molecular weight, as confirmed by western blotting. The final RgpA yield from 1 L of bacterial culture with colony forming unit (CFU) (Log₁₀) 7.4 ± 0.08/mL was of 12.6% (2 mg/mL), with 3.2 FU/μg of amidolytic activity.

CONCLUSIONS

This protocol allows purification of native RgpA from OMV that retains protease activity.

The Relationship Between Porphyromonas Gingivalis and Rheumatoid Arthritis: A Meta-Analysis

Rheumatoid arthritis (RA) is a systematical autoimmune disease, characterized by chronic synovial joint inflammation and hurt. Porphyromonas gingivalis(P. gingivalis) can cause life-threatening inflammatory immune responses in humans when the host pathogenic clearance machinery is disordered. Some epidemiological studies have reported that P. gingivalis exposure would increase the prevalence of RA. However, the results remain inconsistent. Therefore, a meta-analysis was done to systematically analyze the relationship between P. gingivalis exposure and the prevalence of rheumatoid arthritis. Database including Cochrane Library, Web of Science, PubMed, and EMBASE were searched for published epidemiological articles assessed the relationship between P. gingivalis and RA. Obtained studies were screened based on the predefined inclusion and exclusion criteria. The overall Odds Ratios (ORs) of incorporated articles were pooled by random-effect model with STATA 15.1 software. The literature search returned a total of 2057 studies. After exclusion, 28 articles were included and analyzed. The pooled ORs showed a significant increase in the risk of RA in individuals with P. gingivalis exposure (OR = 1.86; 95% CI: 1.43-2.43). Subgroup analysis revealed that pooled ORs from populations located in Europe (OR = 2.17; 95% CI: 1.46-3.22) and North America (OR = 2.50; 95% CI: 1.23-5.08) were significantly higher than that from population in Asia (OR = 1.11; 95% CI: 1.03-1.20). Substantial heterogeneity was observed but did not significantly influence the overall outcome. In conclusion, our results indicated P. gingivalis exposure was a risk factor in RA. Prompt diagnosis and management decisions on P. gingivalis antimicrobial therapy would prevent rheumatoid arthritis development and progression.

Antihuman Endogenous Retrovirus Immune Response and Adaptive Dysfunction in Autism

ASD is a neurodevelopmental disorder of unknown aetiology but with a known contribution of pathogenic immune-mediated mechanisms. HERVs are associated with several neuropsychiatric diseases, including ASD. We studied anti-HERV-W, -K and -H-env immune profiles in ASD children to analyse differences between their respective mothers and child/mother control pairs and possible correlations to ASD severity and loss of adaptive abilities. Of the 84 studied individuals, 42 children (23 ASD and 19 neurotypical) and their paired mothers underwent clinical and neuropsychological evaluations. ASD severity was analysed with standardised tests. Adaptive functioning was studied with ABAS-II and GAC index. Plasma anti-env responses of HERV-K, -H and -W were tested with indirect ELISA. ASD and neurotypical children did not differ in age, gender, comorbidities and anti-HERV responses. In children with ASD, anti-HERV levels were not correlated to ASD severity, while a significant inverse correlation was found between anti-HERV-W-248-262 levels and adaptive/social abilities. Upregulation of anti-HERV-W response correlates to dysfunctional social and adaptive competences in ASD but not in controls, suggesting anti-HERV response plays a role in the appearance of peculiar ASD symptoms.

Mycobacterium paratuberculosis zoonosis is a One Health emergency

A singular pathogen has been killing animals, contaminating food and causing an array of human diseases. Mycobacterium avium subspecies paratuberculosis (MAP) is the cause of a fatal enteric infectious disease called Johne's (Yo'-nees), a disorder mostly studied in ruminant animals. MAP is globally impacting animal health and imparting significant economic burden to animal agriculture. Confounding the management of Johne's disease is that animals are typically infected as calves and while commonly not manifesting clinical disease for years, they shed MAP in their milk and feces in the interval. This has resulted in a "don't test, don't tell" scenario for the industry resulting in greater prevalence of Johne's disease; furthermore, because MAP survives pasteurization, the contaminated food supply provides a source of exposure to humans. Indeed, greater than 90% of dairy herds in the US have MAP-infected animals within the herd. The same bacterium, MAP, is the putative cause of Crohn's disease in humans. Countries historically isolated from importing/exporting ruminant animals and free of Johne's disease subsequently acquired the disease as a consequence of opening trade with what proved to be infected animals. Crohn's disease in those populations became a lagging indicator of MAP infection. Moreover, MAP is associated with an increasingly long list of human diseases. Despite MAP scientists entreating regulatory agencies to designate MAP a "zoonotic agent," it has not been forthcoming. One Health is a global endeavor applying an integrative health initiative that includes the environment, animals and humans; One Health asserts that stressors affecting one affects all three. Recognizing the impact MAP has on animal and human health as well as on the environment, it is time for One Health, as well as other global regulatory agencies, to recognize that MAP is causing an insidious slow-motion tsunami of zoonosis and implement public health mitigation.

A Comparative and Comprehensive Review of Antibody Applications in the Treatment of Lung Disease

Antibodies are a type of protein produced by active B cells in response to antigen stimulation. A series of monoclonal antibodies and neutralizing antibodies have been invented and put into clinical use because of their high therapeutic effect and bright developing insight. Patients with cancer, infectious diseases, and autoimmune diseases can all benefit from antibody therapy. However, the targeting aspects and potential mechanisms for treating these diseases differ. In the treatment of patients with infectious diseases such as COVID-19, neutralizing antibodies have been proposed as reliable vaccines against COVID-19, which target the ACE2 protein by preventing virus entry into somatic cells. Monoclonal antibodies can target immune checkpoints (e.g., PD-L1 and CTLA-4), tyrosine kinase and subsequent signaling pathways (e.g., VEGF), and cytokines in cancer patients (e.g. IL-6 and IL-1β). It is debatable whether there is any connection between the use of antibodies in these diseases. It would be fantastic to discover the related points and explain the burden for the limitation of cross-use of these techniques. In this review, we provided a comprehensive overview of the use of antibodies in the treatment of infectious disease and cancer patients. There are also discussions of their mechanisms and history. In addition, we discussed our future outlook on the use of antibodies.