Serum and urine lipidomic profiles identify biomarkers diagnostic for seropositive and seronegative rheumatoid arthritis.

Objective: Seronegative rheumatoid arthritis (RA) is defined as RA without circulating autoantibodies such as rheumatoid factor and anti-citrullinated protein antibodies; thus, early diagnosis of seronegative RA can be challenging. Here, we aimed to identify diagnostic biomarkers for seronegative RA by performing lipidomic analyses of sera and urine samples from patients with RA. Methods: We performed untargeted lipidomic analysis of sera and urine samples from 111 RA patients, 45 osteoarthritis (OA) patients, and 25 healthy controls (HC). These samples were divided into a discovery cohort (n = 97) and a validation cohort (n = 84). Serum samples from 20 patients with systemic lupus erythematosus (SLE) were also used for validation. Results: The serum lipidome profile of RA was distinguishable from that of OA and HC. We identified a panel of ten serum lipids and three urine lipids in the discovery cohort that showed the most significant differences. These were deemed potential lipid biomarker candidates for RA. The serum lipid panel was tested using a validation cohort; the results revealed an accuracy of 79%, a sensitivity of 71%, and a specificity of 86%. Both seropositive and seronegative RA patients were differentiated from patients with OA, SLE, and HC. Three urinary lipids showing differential expression between RA from HC were identified with an accuracy of 84%, but they failed to differentiate RA from OA. There were five lipid pathways that differed between seronegative and seropositive RA. Conclusion: Here, we identified a panel of ten serum lipids as potential biomarkers that can differentiate RA from OA and SLE, regardless of seropositivity. In addition, three urinary lipids had diagnostic utility for differentiating RA from HC.

Interferon-gamma signaling promotes cartilage regeneration after injury.

Osteoarthritis is a common chronic disease and major cause of disability and chronic pain in ageing populations. In this pathology, the entire joint is involved, and the regeneration of articular cartilage still remains one of the main challenges. Here, we investigated the molecular mechanisms underlying cartilage regeneration in young mice using a full-thickness cartilage injury (FTCI) model. FTCI-induced cartilage defects were created in the femoral trochlea of young and adult C57BL/6 mice. To identify key molecules and pathways involved in the early response to cartilage injury, we performed RNA sequencing (RNA-seq) analysis of cartilage RNA at 3 days after injury. Young mice showed superior cartilage regeneration compared to adult mice after cartilage injury. RNA-seq analysis revealed significant upregulation of genes associated with the immune response, particularly in the IFN-γ signaling pathway and qRT-PCR analysis showed macrophage polarization in the early phase of cartilage regeneration (3 days) in young mice after injury, which might promote the removal of damaged or necrotic cells and initiate cartilage regeneration in response to injury. IFN-γR1- and IFN-γ-deficient mice exhibited impaired cartilage regeneration following cartilage injury. DMM-induced and spontaneous OA phenotypes were exacerbated in IFN-γR1-/- mice than in wild-type mice. Our data support the hypothesis that IFN-γ signaling is necessary for cartilage regeneration, as well as for the amelioration of post-traumatic and age-induced OA.

Serum amyloid A expression in liver promotes synovial macrophage activation and chronic arthritis via NFAT5.

Nuclear factor of activated T-cells 5 (NFAT5), an osmo-sensitive transcription factor, can be activated by isotonic stimuli, such as infection. It remains unclear, however, whether NFAT5 is required for damage-associated molecular pattern-triggered (DAMP-triggered) inflammation and immunity. Here, we found that several DAMPs increased NFAT5 expression in macrophages. In particular, serum amyloid A (SAA), primarily generated by the liver, substantially upregulated NFAT5 expression and activity through TLR2/4-JNK signalling pathway. Moreover, the SAA-TLR2/4-NFAT5 axis promoted migration and chemotaxis of macrophages in an IL-6- and chemokine ligand 2-dependent (CCL2-dependent) manner in vitro. Intraarticular injection of SAA markedly accelerated macrophage infiltration and arthritis progression in mice. By contrast, genetic ablation of NFAT5 or TLR2/4 rescued the pathology induced by SAA, confirming the SAA-TLR2/4-NFAT5 axis in vivo. Myeloid-specific depletion of NFAT5 also attenuated SAA-accelerated arthritis. Of note, inflammatory arthritis in mice strikingly induced SAA overexpression in the liver. Conversely, forced overexpression of the SAA gene in the liver accelerated joint damage, indicating that the liver contributes to bolstering chronic inflammation at remote sites by secreting SAA. Collectively, this study underscores the importance of the SAA-TLR2/4-NFAT5 axis in innate immunity, suggesting that acute phase reactant SAA mediates mutual interactions between liver and joints and ultimately aggravates chronic arthritis by enhancing macrophage activation.

Cytokines, Vascular Endothelial Growth Factors, and PlGF in Autoimmunity: Insights From Rheumatoid Arthritis to Multiple Sclerosis.

In this review, we will explore the intricate roles of cytokines and vascular endothelial growth factors in autoimmune diseases (ADs), with a particular focus on rheumatoid arthritis (RA) and multiple sclerosis (MS). AD is characterized by self-destructive immune responses due to auto-reactive T lymphocytes and Abs. Among various types of ADs, RA and MS possess inflammation as a central role but in different sites of the patients. Other common aspects among these two ADs are their chronicity and relapsing-remitting symptoms requiring continuous management. First factor inducing these ADs are cytokines, such as IL-6, TNF-α, and IL-17, which play significant roles in the pathogenesis by contributing to inflammation, immune cell activation, and tissue damage. Secondly, vascular endothelial growth factors, including VEGF and angiopoietins, are crucial in promoting angiogenesis and inflammation in these two ADs. Finally, placental growth factor (PlGF), an emerging factor with bi-directional roles in angiogenesis and T cell differentiation, as we introduce as an "angio-lymphokine" is another key factor in ADs. Thus, while angiogenesis recruits more inflammatory cells into the peripheral sites, cytokines secreted by effector cells play critical roles in the pathogenesis of ADs. Various therapeutic interventions targeting these soluble molecules have shown promise in managing autoimmune pathogenic conditions. However, delicate interplay between cytokines, angiogenic factors, and PlGF has more to be studied when considering their complementary role in actual pathogenic conditions. Understanding the complex interactions among these factors provides valuable insights for the development of innovative therapies for RA and MS, offering hope for improved patient outcomes.

The acute phase reactant orosomucoid-2 directly promotes rheumatoid inflammation.

Acute phase proteins involved in chronic inflammatory diseases have not been systematically analyzed. Here, global proteome profiling of serum and urine revealed that orosomucoid-2 (ORM2), an acute phase reactant, was differentially expressed in rheumatoid arthritis (RA) patients and showed the highest fold change. Therefore, we questioned the extent to which ORM2, which is produced mainly in the liver, actively participates in rheumatoid inflammation. Surprisingly, ORM2 expression was upregulated in the synovial fluids and synovial membranes of RA patients. The major cell types producing ORM2 were synovial macrophages and fibroblast-like synoviocytes (FLSs) from RA patients. Recombinant ORM2 robustly increased IL-6, TNF-α, CXCL8 (IL-8), and CCL2 production by RA macrophages and FLSs via the NF-κB and p38 MAPK pathways. Interestingly, glycophorin C, a membrane protein for determining erythrocyte shape, was the receptor for ORM2. Intra-articular injection of ORM2 increased the severity of arthritis in mice and accelerated the infiltration of macrophages into the affected joints. Moreover, circulating ORM2 levels correlated with RA activity and radiographic progression. In conclusion, the acute phase protein ORM2 can directly increase the production of proinflammatory mediators and promote chronic arthritis in mice, suggesting that ORM2 could be a new therapeutic target for RA.

Predictors of renal relapse in Koreans with lupus nephritis after achieving complete response: a 35-years of experience at a single center.

BACKGROUND/AIMS: Renal relapse has known to be a poor prognostic factor in patients with lupus nephritis (LN), but there were few studies that identified the risk factors of renal relapse in real world. We conducted this study based on 35-years of experience at a single center to find out predictors of renal relapse in Korean patients with LN after achieving complete response (CR). METHODS: We retrospectively analyzed the clinical, laboratory, pathologic and therapeutic parameters in 296 patients of LN who reached CR. The cumulative risk and the independent risk factors for renal relapse were examined by Kaplan-Meier methods and Cox proportional hazards regression analyses, respectively. RESULTS: The median follow-up period from CR was 123 months. Renal relapse had occurred in 157 patients. Renal relapse occurred in 38.2%, 57.6% and 67.9% of patients within 5-, 10-, and 20-year, respectively. The age at diagnosis of SLE and LN were significantly younger, and the proportions of severe proteinuria and serum hypoalbuminemia were higher in patients with renal relapse. Interestingly, the proportion of receiving cytotoxic maintenance treatment was higher in patients with renal relapse. In Cox proportional hazards regression analyses, only young-age onset of LN (by 10 years, HR = 0.779, p = 0.007) was identified to independent predictor of renal relapse. CONCLUSION: Young-age onset of LN was only independent predictor and the patients with severe proteinuria and serum hypoalbuminemia also tended to relapse more, despite of sufficient maintenance treatment. Studies on more effective maintenance treatment regimens and duration are needed to reduce renal relapse.

Nuclear receptor coactivator 6 is a critical regulator of NLRP3 inflammasome activation and gouty arthritis.

Transcriptional coactivators regulate the rate of gene expression in the nucleus. Nuclear receptor coactivator 6 (NCOA6), a coactivator, has been implicated in embryonic development, metabolism, and cancer pathogenesis, but its role in innate immunity and inflammatory diseases remains unclear. Here, we demonstrated that NCOA6 was expressed in monocytes and macrophages and that its level was increased under proinflammatory conditions. Unexpectedly, nuclear NCOA6 was found to translocate to the cytoplasm in activated monocytes and then become incorporated into the inflammasome with NLRP3 and ASC, forming cytoplasmic specks. Mechanistically, NCOA6 associated with the ATP hydrolysis motifs in the NACHT domain of NLRP3, promoting the oligomerization of NLRP3 and ASC and thereby instigating the production of IL-1ß and active caspase-1. Of note, Ncoa6 deficiency markedly inhibited NLRP3 hyperactivation caused by the Nlrp3R258W gain-of-function mutation in macrophages. Genetic ablation of Ncoa6 substantially attenuated the severity of two NLRP3-dependent diseases, folic-induced acute tubular necrosis and crystal-induced arthritis, in mice. Consistent with these findings, NCOA6 was highly expressed in macrophages derived from gout patients, and NCOA6-positive macrophages were significantly enriched in gout macrophages according to the transcriptome profiling results. Conclusively, NCOA6 is a critical regulator of NLRP3 inflammasome activation and is therefore a promising target for NLRP3-dependent diseases, including gout.

A single-centre retrospective study of factors affecting steroid-free remission of immunoglobulin G4-related disease conducted in South Korea: A notable outcome after complete resection.

OBJECTIVES: Few studies have examined factors affecting steroid-free remission (SFR) in patients with immunoglobulin G4-related disease (IgG4-RD). The aim of this study was to investigate clinical factors affecting SFR in IgG4-RD. METHODS: The medical records of 68 patients who met the 2020 revised comprehensive diagnostic criteria for IgG4-RD were reviewed retrospectively. SFR was defined as remission maintained for at least 6 months without corticosteroids. Cox regression analysis was performed to examine the associations between SFR and various clinical factors. The relapse rate after SFR was examined using the log-rank test. RESULTS: After a median follow-up of 36 months, 30.9% (21/68) of patients with IgG4-RD achieved SFR. Multivariate Cox regression analysis revealed that IgG4-RD diagnosed by complete resection rather than by common diagnostic procedures was the only factor positively associated with SFR (hazard ratio, 7.41; 95% confidence interval, 2.23-24.60; P = .001). Furthermore, relapse after attainment of SFR was significantly less common in the group that underwent complete resection than in the group that did not undergo complete resection (log-rank P = .006). CONCLUSIONS: Patients with IgG4-RD diagnosed by complete resection had a higher likelihood of achieving SFR and a lower rate of relapse after attaining SFR.

Characteristics of patients with psoriatic arthritis in Korea: focusing on axial involvement.

BACKGROUND/AIMS: We aimed to clarify the clinical characteristics of psoriatic arthritis (PsA) in Korean patients focusing on PsA with axial involvement. METHODS: A retrospective medical chart review was performed to identify PsA patients at a single tertiary center. Cases of AS patients with psoriasis were recruited from a prospective AS registry of the same center. Demographics, laboratory findings, and radiologic characteristics were assessed. RESULTS: A total of 69 PsA patients were identified. In PsA patients, spondylitis (46.4%) was the most common form. Compared to AS patients with psoriasis, PsA patients with radiographic axial involvement were older (50.9 vs. 32.4 years; p < 0.001) and showed greater peripheral disease activity (peripheral arthritis 78.1 vs. 12.5%, p < 0.001; enthesitis 50.0 vs. 6.3%, p = 0.003). AS patients with psoriasis presented a higher rate of HLA-B*27 positivity (81.3 vs. 17.2%; p < 0.001) and a more frequent history of inflammatory back pain (100.0 vs. 75.0%; p = 0.039) than PsA patients with radiographic axial involvement. Significant proportions of PsA patients with radiographic axial involvement had cervical spine involvement (10/18, 55.6%) and spondylitis without sacroiliitis (10/23, 43.5%). CONCLUSION: We demonstrate that axial involvement is common in Korean PsA patients, and its characteristics can be distinct from those of AS.

A causative role for periarticular skeletal muscle weakness in the progression of joint damage and pain in OA.

Although osteoarthritis (OA) is regarded as a disease of the articular cartilage, recent research has demonstrated alterations in periarticular muscles that surround the affected joint. Here, we investigated changes in periarticular muscle during the progression of OA, as well as the cause-and-effect relationship between muscle weakness and OA, in a mouse model of OA by destabilization of the medial meniscus (DMM). Pathological phenotypes in the periarticular muscles were assessed in the early and late stages of OA by DMM. OA pathology and pain behavior in the mice after DMM induction were examined in response to periarticular muscle weakness induced by multiple rounds of barium chloride (BaCl2) injections. The examinations were also performed in myostatin knockout mice with strengthened muscle phenotypes by muscle hypertrophy. Morphological alterations in the tibialis anterior (TA) and quadriceps muscles in DMM mice included variations in muscle-fiber size, aberrant extracellular matrix (ECM) deposition, inflammatory cell infiltration, and decreased muscle mass. Periarticular muscle fibers isolated from DMM mice showed reductions in the number of satellite cells and myogenic capacity of primary myoblast, as well as proliferation. DMM + muscle injury mice also showed exacerbated joint degeneration compared to the DMM vehicles. Myostatin knockout mice were characterized by attenuated OA and the complete abrogation of pain behavior after DMM. Our results suggest an association between muscle weakness and OA progression and pain.

Changes in the cholesterol profile of patients with rheumatoid arthritis treated with biologics or Janus kinase inhibitors.

Objective: To assess the effects of biological and targeted synthetic disease-modifying antirheumatic drugs (DMARDs) on lipid profiles in patients with moderate-to-severe rheumatoid arthritis (RA). Methods: This retrospective single-center observational study included patients with RA taking a tumor necrosis factor-α inhibitor (TNFi), abatacept, tocilizumab, or a Janus kinase inhibitor (JAKi) for at least 6 months. Changes in lipid profile were assessed at 6 months after the start of treatment, and associations between changes in lipid profiles and clinical efficacy, concomitant medications, and comorbidities were evaluated. Results: This study included 114 patients treated with TNFi, 81 with abatacept, 103 with tocilizumab, and 89 with JAKi. The mean percentage change (from baseline to 6 months) in total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and non-HDL-C levels was higher in those taking tocilizumab and JAKi than in those taking TNFi and abatacept. A significant change in non-HDL-C was associated with JAKi (versus TNFi odds ratio [OR], 3.228; 95% confidence interval [CI], 1.536~6.785), tocilizumab (versus TNFi OR, 2.203; 95% CI, 1.035~4.689), and statins (OR, 0.487; 95% CI, 0.231~1.024). However, changes in disease activity in 28 joints were not associated with a significant change in non-HDL-C. Conclusion: Tocilizumab- and JAKi-associated increases in serum non-HDL-C levels were observed regardless of changes in disease activity. Statins are recommended for RA patients showing a significant increase in cholesterol levels after initiating biological and targeted synthetic DMARDs.

Salivary ultrasonography and histopathologic evaluation of secondary Sjögren's syndrome in rheumatoid arthritis patients.

Novel modalities, such as salivary ultrasonography (SGUS) and shear wave elastography (SWE), have previously been introduced to evaluate Sjögren's syndrome (SS). However, in secondary SS (sSS), the diagnostic performance of SGUS and its relationship with clinicopathological characteristics have not yet been clearly defined. In this study, we aimed to investigate sSS in RA patients using SGUS and SWE and sought to determine its pathological correlations. Thirty-one RA patients who presented with sicca symptoms were included to be evaluated on SS, and were compared with 18 primary SS (pSS) patients. All subjects were assessed through SGUS, SWE, and conventional diagnostic approaches for SS, including minor salivary gland biopsy (MSGB). In SGUS evaluation, two separate scoring systems, suggested by Hocevar and OMERACT, were used. Among 31 RA patients with sicca symptoms, 19 (61.2%) were diagnosed as sSS. Similar to pSS, SGUS showed good diagnostic performance (sensitivity 68.4% and 78.9%, and specificity 91.7% and 75.0% for Hocever and OMERACT, respectively) in differentiating sSS from RA patients with simple sicca symptoms. The sSS and pSS patients exhibited significantly higher lymphoid infiltration areas in MSGB than RA patients without SS. Focus score and lymphoid infiltration areas correlated well with sonographic severity. Severity of fibrosis in MSGB showed better positive correlation with SWE than with SGUS. Similar to pSS, SGUS shows good diagnostic performance for sSS in RA patients. SWE reflects histopathologic chronicity of MSGB well in both pSS and sSS.

Role of high-temperature requirement serine protease A 2 in rheumatoid inflammation.

BACKGROUND: High-temperature requirement serine protease A 2 (HtrA2) is known to be involved in growth, unfolded protein response to stress, apoptosis, and autophagy. However, whether HtrA2 controls inflammation and immune response remains elusive. METHODS: Expression of HtrA2 in the synovial tissue of patients was examined using immunohistochemistry and immunofluorescence staining. Enzyme-linked immunosorbent assay was used to determine the concentrations of HtrA2, interleukin-6 (IL-6), interleukin-8 (IL-8), chemokine (C-C motif) ligand 2 (CCL2), and tumor necrosis factor α (TNFα). Synoviocyte survival was assessed by MTT assay. For the downregulation of HtrA2 transcripts, cells were transfected with HtrA2 siRNA. RESULTS: We found that the concentration of HtrA2 was elevated in rheumatoid arthritis (RA) synovial fluid (SF) than in osteoarthritis (OA) SF, and its concentrations were correlated with the number of immune cells in the RA SF. Interestingly, HtrA2 levels in the SF of RA patients were elevated in proportion to synovitis severity and correlated with the expression of proinflammation cytokines and chemokines, such as IL-6, IL-8, and CCL2. In addition, HtrA2 was highly expressed in RA synovium and primary synoviocytes. RA synoviocytes released HtrA2 when stimulated with ER stress inducers. Knockdown of HtrA2 inhibited the IL1ß-, TNFα-, and LPS-induced release of proinflammatory cytokines and chemokines by RA synoviocytes. CONCLUSION: HtrA2 is a novel inflammatory mediator and a potential target for the development of an anti-inflammation therapy for RA.

Identification of MYH9 as a key regulator for synoviocyte migration and invasion through secretome profiling.

OBJECTIVES: 'Invasive pannus' is a pathological hallmark of rheumatoid arthritis (RA). This study aimed to investigate secretome profile of synovial fibroblasts of patients with RA (RA-FLSs), a major cell type comprising the invasive pannus. METHODS: Secreted proteins from RA-FLSs were first identified using liquid chromatography-tandem mass spectrometry analysis. Ultrasonography was performed for affected joints to define synovitis severity at the time of arthrocentesis. Expression levels of myosin heavy chain 9 (MYH9) in RA-FLSs and synovial tissues were determined by ELISA, western blot analysis and immunostaining. A humanised synovitis model was induced in immuno-deficient mice. RESULTS: We first identified 843 proteins secreted from RA-FLSs; 48.5% of the secretome was associated with pannus-driven pathologies. Parallel reaction monitoring analysis of the secretome facilitated discovery of 16 key proteins related to 'invasive pannus', including MYH9, in the synovial fluids, which represented synovial pathology based on ultrasonography and inflammatory activity in the joints. Particularly, MYH9, a key protein in actin-based cell motility, showed a strong correlation with fibroblastic activity in the transcriptome profile of RA synovia. Moreover, MYH9 expression was elevated in cultured RA-FLSs and RA synovium, and its secretion was induced by interleukin-1ß, tumour necrosis factor α, toll-like receptor ligation and endoplasmic reticulum stimuli. Functional experiments demonstrated that MYH9 promoted migration and invasion of RA-FLSs in vitro and in a humanised synovitis model, which was substantially inhibited by blebbistatin, a specific MYH9 inhibitor. CONCLUSIONS: This study provides a comprehensive resource of the RA-FLS-derived secretome and suggests that MYH9 represents a promising target for retarding abnormal migration and invasion of RA-FLSs.

Factors associated with the composition of the gut microbiome in patients with established rheumatoid arthritis and its value for predicting treatment responses.

BACKGROUND: We aimed to investigate the gut microbiota of patients with established rheumatoid arthritis (RA) who have been managed with disease-modifying anti-rheumatic drugs (DMARDs) for a long time. We focused on factors that might affect composition of the gut microbiota. Furthermore, we investigated whether gut microbiota composition predicts future clinical responses to conventional synthetic DMARDs (csDMARDs) in patients with an insufficient response to initial therapy. METHODS: We recruited 94 patients with RA and 30 healthy participants. Fecal gut microbiome was analyzed by 16S rRNA amplificon sequencing; the resulting raw reads were processed based on QIIME2. Calypso online software was used for data visualization and to compare microbial composition between groups. For RA patients with moderate-to-high disease activity, treatment was changed after stool collection, and responses were observed 6 months later. RESULTS: The composition of the gut microbiota in patients with established RA was different from that of healthy participants. Young RA patients (< 45 years) had reduced richness, evenness, and distinct gut microbial compositions when compared with older RA patients and healthy individuals. Disease activity and rheumatoid factor levels were not associated with microbiome composition. Overall, biological DMARDs and csDMARDs, except sulfasalazine and TNF inhibitors, respectively, were not associated with the gut microbial composition in patients with established RA. However, the combination of Subdoligranulum and Fusicatenibacter genera was associated with a future good response to second-line csDMARDs in patients who showed an insufficient response to first-line csDMARDs. CONCLUSION: Gut microbial composition in patients with established RA is different from that in healthy individuals. Thus, the gut microbiome has the potential to predict responses of some RA patients to csDMARDs.

Protective role of colitis in inflammatory arthritis via propionate-producing Bacteroides in the gut.

Objectives: To investigate whether and how inflammatory disease in the intestine influences the development of arthritis, considering that organ-to-organ communication is associated with many physiological and pathological events. Methods: First, mice were given drinking water containing dextran sodium sulfate (DSS) and then subjected to inflammatory arthritis. We compared the phenotypic symptoms between the cohoused and separately-housed mice. Next, donor mice were divided into DSS-treated and untreated groups and then cohoused with recipient mice. Arthritis was then induced in the recipients. The fecal microbiome was analyzed by 16S rRNA amplicon sequencing. We obtained type strains of the candidate bacteria and generated propionate-deficient mutant bacteria. Short-chain fatty acids were measured in the bacterial culture supernatant, serum, feces, and cecum contents using gas chromatography-mass spectrometry. Mice fed with candidate and mutant bacteria were subjected to inflammatory arthritis. Results: Contrary to expectations, the mice treated with DSS exhibited fewer symptoms of inflammatory arthritis. Intriguingly, the gut microbiota contributes, at least in part, to the improvement of colitis-mediated arthritis. Among the altered microorganisms, Bacteroides vulgatus and its higher taxonomic ranks were enriched in the DSS-treated mice. B. vulgatus, B. caccae, and B. thetaiotaomicron exerted anti-arthritic effects. Propionate production deficiency further prevented the protective effect of B. thetaiotaomicron on arthritis. Conclusions: We suggest a novel relationship between the gut and joints and an important role of the gut microbiota as communicators. Moreover, the propionate-producing Bacteroides species examined in this study may be a potential candidate for developing effective treatments for inflammatory arthritis.

Mycobacterium potentiates protection from colorectal cancer by gut microbial alterations.

Not only are many Mycobacteria pathogens, but they can act as strong non-specific immunopotentiators, generating beneficial effects on the pathogenesis of some diseases. However, there has been no direct evidence of the effect of mycobacterial species on colorectal cancer (CRC). Herein, we showed that there may be a meaningful inverse correlation between the incidence of tuberculosis and CRC based on global statistics and that heat-killed Mycobacterial tuberculosis and live Mycobacterium bovis (Bacillus Calmette-Guérin strain) could ameliorate CRC development. In particular, using a faecal microbiota transplantation and a comparison between separate housing and cohousing, we demonstrated that the gut microbiota is involved in the protective effects. The microbial alterations can be elucidated by the modulation of antimicrobial activities including those of the Reg3 family genes. Furthermore, interleukin-22 production by T helper cells contributed to the anti-inflammatory activity of Mycobacteria. Our results revealed a novel role of Mycobacteria involving gut microbial alterations in dampening inflammation-associated CRC and an immunological mechanism underlying the interaction between microbes and host immunity.

Dysbiotic but nonpathogenic shift in the fecal mycobiota of patients with rheumatoid arthritis.

Rheumatoid arthritis (RA) is closely associated with the oral and gut microbiomes. Fungal cell wall components initiate inflammatory arthritis in mouse models. However, little is known regarding the role of the fungal community in the pathogenesis of RA. To evaluate the association between RA and the gut microbiome, investigations of bacterial and fungal communities in patients with RA are necessary. Therefore, we investigated the compositions and associations of fecal bacterial and fungal communities in 30 healthy controls and 99 patients with RA. The relative abundances of Bifidobacterium and Blautia decreased, whereas the relative abundance of Streptococcus increased, in patients with RA. The relative abundance of Candida in the fecal fungal community was higher in patients with RA than in healthy controls, while the relative abundance of Aspergillus was higher in healthy controls than in patients with RA. Candida species-specific gene amplification showed that C. albicans was the most abundant species of Candida. Ordination analysis and random forest classification models supported the findings of structural changes in bacterial and fungal communities. Aspergillus was the core fecal fungal genus in healthy controls, although Saccharomyces spp. are typically predominant in Western cohorts. In addition, bacterial-fungal association analyses showed that the hub node had shifted from fungi to bacteria in patients with RA. The finding of fungal dysbiosis in patients with RA suggests that fungi play critical roles in the fecal microbial communities and pathogenesis of RA.

Differential effects of periodontal microbiome on the rheumatoid factor induction during rheumatoid arthritis pathogenesis.

Association between exposure to periodontal bacteria and development of autoantibodies related to rheumatoid arthritis (RA) has been widely accepted; however, direct causal relationship between periodontal bacteria and rheumatoid factor (RF) is currently not fully understood. We investigated whether periodontal bacteria could affect RF status. Patients with preclinical, new-onset, or chronic RA underwent periodontal examination, and investigation of subgingival microbiome via 16S rRNA sequencing. Degree of arthritis and RF induction was examined in collagen-induced arthritis (CIA) mice that were orally inoculated with different periodontal bacteria species. Subsequently, single-cell RNA sequencing analysis of the mouse spleen cells was performed. Patients with preclinical RA showed an increased abundance of the Porphyromonadacae family in the subgingival microbiome compared to those with new-onset or chronic RA, despite comparable periodontitis severity among them. Notably, a distinct subgingival microbial community was found between patients with high-positive RF and those with negative or low-positive RF (p=0.022). Oral infections with the periodontal pathogens P. gingivalis and Treponema denticola in CIA mice similarly enhanced arthritis score, but resulted in different levels of RF induction. Genes related to B cell receptor signaling, B cell proliferation, activation, and differentiation, and CD4+ T cell costimulation and cytokine production were involved in the differential induction of RF in mice exposed to different bacteria. In summary, periodontal microbiome might shape RF status by affecting the humoral immune response during RA pathogenesis.

Targeted Immunotherapy for Autoimmune Disease.

In the past few decades, biological drugs and small molecule inhibitors targeting inflammatory cytokines, immune cells, and intracellular kinases have become the standard-of-care to treat autoimmune diseases. Inhibition of TNF, IL-6, IL-17, and IL-23 has revolutionized the treatment of autoimmune diseases, such as rheumatoid arthritis, ankylosing spondylitis, and psoriasis. B cell depletion therapy using anti-CD20 mAbs has shown promising results in patients with neuroinflammatory diseases, and inhibition of B cell survival factors is approved for treatment of systemic lupus erythematosus. Targeting co-stimulatory molecules expressed on Ag-presenting cells and T cells is also expected to have therapeutic potential in autoimmune diseases by modulating T cell function. Recently, small molecule kinase inhibitors targeting the JAK family, which is responsible for signal transduction from multiple receptors, have garnered great interest in the field of autoimmune and hematologic diseases. However, there are still unmet medical needs in terms of therapeutic efficacy and safety profiles. Emerging therapies aim to induce immune tolerance without compromising immune function, using advanced molecular engineering techniques.