Effect of Mycoplasma bovis on expression of inflammatory cytokines and matrix metalloproteinases mRNA in bovine synovial cells

Innate immune response of bovine mammary epithelial cells in Mycoplasma bovis mastitis using an in vitro model of bovine mammary gland infection

Mycoplasma bovis mastitisis highly contagious and disrupts lactation, posing a significant threat to the dairy industry. While the mammary gland's defence mechanism involves epithelial cells and mononuclear cells (MNC), their interaction with M. bovis remains incompletely understood. In this study, we assessed the immunological reactivity of bovine mammary epithelial cells (bMEC) to M. bovis through co-culture with MNC. Upon co-culture with MNC, the mRNA expression levels of interleukin (IL)-1β, IL-6, IL-8 and tumor necrosis factor (TNF)-α in bMEC stimulated by M. bovis showed a significant increase compared to monoculture. Additionally, when stimulated with M. bovis, the culture supernatant exhibited significantly higher concentrations of IL-6 and interferon (IFN)-γ, while IL-1β concentration tended to be higher in co-culture with MNC than in monoculture. Furthermore, the mRNA expression levels of toll-like receptor (TLR) 2 in bMEC stimulated with M. bovis tended to increase, and TLR4 significantly increased when co-cultured with MNC compared to monocultures. However, the surface expression levels in bMEC did not exhibit significant changes between co-culture and monoculture. Overall, our research indicates that the inflammatory response of bMEC is increased during co-culture with MNC, suggesting that the interaction between bMEC and MNC in the mammary gland amplifies the immune response to M. bovis in cows affected by M. bovis mastitis.

Characteristics of Mycoplasma bovis, Mycoplasma arginini, and Mycoplasma californicum on immunological response of bovine synovial cells

Mycoplasma arthritis in calves caused by M. bovis exhibits joint swelling, lameness, and immobility. In contrast to M. bovis, M. arginini, and M. californicum which were similarly isolated from the affected joints, only induced mild inflammation. The changes in pathogenesis that depended on species, however, remained unknown. This investigation aims to examine the characteristics of immune responses to M. bovis, M. arginini, and M. californicum in synovial cells. Intracellular M. bovis was detected by gentamicin assay, but M. arginini and M. californicum were not detected. M. bovis-infected synovial cells were encouraged to proliferate and had their apoptosis suppressed. We suggest that M. bovis invaded and inhibited apoptosis of synovial to evade host immunity, which led to long term survival in joints. M. bovis infection significantly increased IL-6 mRNA expression compared to control, although M. arginini and M. californicum infection were comparable to control. We suggest that M. arginini and M. californicum have low abilities to induce inflammation in joints and therefore do not cause severe pathology. Our findings are the first to show the variations in synovial cell immune responses to M. bovis, M. arginini, and M. californicum, which are thought to be related to the pathogenicity of arthritis.

Annexin A2 regulates Mycoplasma bovis adhesion and invasion to embryo bovine lung cells affecting molecular expression essential to inflammatory response

Mycoplasma bovis (M. bovis) is an important pathogen of the bovine respiratory disease complex, invading lower respiratory tracts and causing severe pneumonia. However, its molecular mechanism largely remains unknown. Host annexin A2 (ANXA2) is a calcium-dependent phospholipid-binding protein. The current study sought to determine whether ANXA2 could mediate M. bovis adhesion and invasion thereby affecting its induction of inflammatory response. ANXA2 expression was upregulated in M. bovis-infected bovine lung epithelial cells (EBL), and blocking ANXA2 with an anti-ANXA2 antibody reduced M. bovis adhesion to EBL. Compared with uninfected cells, more ANXA2 was translocated from the cytoplasm to the cell surface after M. bovis infection. Furthermore, RNA interference knockdown of ANXA2 expression in EBL cells resulted in a significant decrease in M. bovis invasion and F-actin polymerization. Next, the transcriptomic study of M. bovis-infected EBL cells with and without ANXA2 knockdown were performed. The data exhibited that ANXA2 knockdown EBL cells had 2487 differentially expressed genes (DEGs), with 1175 upregulated and 1312 downregulated compared to control. According to GO and KEGG analyses, 50 genes potentially linked to inflammatory responses, 23 involved in extracellular matrix (ECM) receptor interaction, and 48 associated with PI3K-AKT signal pathways were upregulated, while 38 mRNA binding genes, 16 mRNA 3′-UTR binding genes, and 34 RNA transport genes were downregulated. Furthermore, 19 genes with various change-folds were selected for qPCR verification, and the results agreed with the RNA-seq findings. Above all, the transcription of two chemokines (IL-8 and CXCL5) and a key bovine β-defensin TAP in IL-17 signaling pathway were significantly increased in ANXA2 knockdown cells. Moreover, ANXA2 knockdown or knockout could increase NF-κB and MAPK phosphorylation activity in response to M. bovis infection. Additionally, ANXA2 knockdown also significantly decreased the CD44 transcripts via exon V3 and V7 skipping after M. bovis infection. We concluded that M. bovis borrowed host ANXA2 to mediate its adhesion and invasion thereby negatively regulating molecular expression essential to IL-17 signal pathway. Furthermore, CD44 V3 and V7 isoforms might contribute to this ANXA2 meditated processes in M. bovis infected EBL cells. These findings revealed a new understanding of pathogenesis for M. bovis infection.

Effects of intra-articular inoculation with Mycoplasma bovis on immunological responses in calf joints

Mycoplasma arthritis that caused by Mycoplasma bovis exhibit severe lameness. This disease is difficult to cure with antibiotics, but the detailed pathological mechanisms have not been fully clarified. In this study, we examined the effects of intra-articular inoculation with M. bovis on immunological responses in calf joints. We inoculated three calves each with M. bovis or phosphate buffer saline (control) into the right stifle joint and dissected them at 15 days postinoculation. Mycoplasma bovis-inoculated calves exhibited swelling of the stifle joint, increases in synovial fluid, fibrin deposition, and cartilage thinning. Intracellular M. bovis was detected in synovial tissues analyzed by immunohistochemistry and transmission electron microscopy. Messenger RNA expressions of interleukin (IL)-1β, IL-6, IL-8, IL-12p40, and IL-17A in synovial fluid cells and synovial tissues from M. bovis-inoculated calves were significantly higher than those from control calves. Protein levels of these cytokines in synovial fluid from M. bovis-inoculated calves were markedly higher than those from control calves. Our study clarified that inoculation with M. bovis into the stifle joint induced the production of inflammatory cytokines by synovial fluid cells and synovial tissues, causing a severe inflammatory response in joints. Additionally, M. bovis could invade cells in synovial tissues, which may have aided it in evading antibiotics and host immune surveillance.

Secreted MbovP0145 Promotes IL-8 Expression through Its Interactive β-Actin and MAPK Activation and Contributes to Neutrophil Migration

Mycoplasma bovis (M. bovis) is an important pathogen of cattle responsible for huge economic losses in the dairy and beef industries worldwide. The proteins secreted by M. bovis are mainly related to its adhesion, invasion, virulence, and intracellular survival and play a role in mycoplasma-host interactions. In our previous study, we found MbovP0145, a secreted protein present in the M. bovis secretome, but little is known about its function. In this study, we assessed the inflammatory characteristics and underlined mechanism of this inflammation of recombinant MbovP0145 (rMbovP0145). For this, bovine lung epithelial cells (EBL) were stimulated by rMbovP0145 to see the IL-8 production in a time- and dose-dependent manner. We observed that rMbovP0145 increased the production of IL-8 via ERK1/2 and P38 pathway activation. Further, the effect of the M. bovis ΔMbov_0145 mutant and its complementary strain on IL-8 mRNA expression was also confirmed. A pulldown assay of the GST-tagged MbovP0145 protein with mass spectrometry demonstrated that β-actin could specifically interact with rMbovP0145 to mediate the IL-8 signaling. As knockdown of β-actin expression with RNA interference in EBL cells decreased the mRNA expression of IL-8 and the phosphorylated ERK1/2 and P38 proteins, whereas disrupted actin polymerization by cytochalasin D led to a significantly higher IL-8 expression and MAPK phosphorylation in rMbovP0145-stimulated cells. Compared to M. bovis HB0801 and its complementary strain, the culture supernatant of EBL cells infected with the M. bovis ΔMbov_0145 mutant induced less neutrophil migration to the lower chamber in a transwell system. In conclusion, MbovP0145 promoted IL-8 expression by interacting with β-actin through activation of the MAPK pathway, thus contributing to neutrophil migration.

Increasing of matrix metalloproteinase 3 in bovine endometritis

Matrix metalloproteinase 3 (MMP3), a key member of the MMPs family, is involved in the modulation of endometrial inflammation and innate immunity. However, the role of MMP3 in bovine endometritis remains unknown. To investigate the role of MMP3 in bovine endometritis, endometrial MMP3 expression were determined in uterine biopsies from twenty 40-60 days postpartum dairy cows, which six were healthy cows and fourteen were endometritic cows. Moreover, MMP3 expression were also detected at different intensity of inflammatory response, which was induced by graded concentrations (0, 1, 5, 10 μg/ml) of LPS in bovine endometrial epithelial cells (BEECs) in vitro. RT-qPCR was used to test the mRNA levels of MMP3 in tissues or cells. Western blot was conducted to measure protein levels, and enzyme-linked immunosorbent assay (ELISA) was used for TNF-α and IL-1β in cell supernatant. Results showed that MMP3 mRNA and protein levels significantly increased and positive correlative with severity of endometritis in vivo. Likewise, MMP3 expression also positive correlative with intensity of LPS inflammatory response in BEECs in vitro. These results indicate that increasing of MMP3 directly correlates with bovine endometritis, and its increasing may contribute to progression of bovine endometritis.

Research Progress of Therapeutic Enzymes and Their Derivatives: Based on Herbal Medicinal Products in Rheumatoid Arthritis

Rheumatoid arthritis (RA) acts as one of the most common, agnogenic and chronic inflammatory-autoimmune disorder which is characterized by persistent synovitis, cartilage destruction, and joint deformities, leads to a wide range of disabilities, and increased mortality, thus imposing enormous burdens. Several drugs with anti-inflammatory and immunomodulatory properties such as celecoxib, diclofenac and methotrexate are being selected as conventional drugs in the allopathic system of medicine for the treatment of RA in clinic. However, there are some serious side effects more or less when using these drugs because of their short poor bioavailability and biological half-life for a long time. These shortcomings greatly promote the exploration and application of new low- or no-toxicity drugs for treating the RA. Meanwhile, a growing number of studies demonstrate that several herbs present certain anti-inflammatory and anti-arthritic activities through different enzymes and their derivatives, which indicate that they are promising therapeutic strategies when targeting these mediators based on herbal medicinal products in RA research. This review article summarizes the roles of the main enzymes and their derivatives during the pathogenesis of RA, and clearly clarifies the explicit and potential targeted actions of herbal medicinal products that have anti-RA activity. Our review provides timely and critical reference for the scientific rationale use of herbal medicinal products, with the increasing basic research and clinical application of herbal medicinal products by patients with RA.

Inflammatory cytokine mRNA and protein levels in the synovial fluid of Mycoplasma arthritis calves

Bovine Mycoplasma arthritis (MA) is caused by Mycoplasma bovis and exhibits severe clinical symptoms. However, the pathophysiology of bovine MA is incompletely understood. In this study, we examined the cytokine mRNA expression of synovial fluid (SF) cells and cytokine concentrations in the SF of MA calves. The SF was isolated from five clinically healthy (control) and seven MA calves. mRNA and protein levels of interleukin (IL)-1β, IL-6, IL-8, IL-12, and IL-17 in the SF from MA calves were significantly higher than those from control calves. Our results indicate that SF cells produce inflammatory cytokines, which mainly contribute to the severe inflammatory response in the joints of the MA calves.

Invasion of Mycoplasma bovis into bovine synovial cells utilizing the clathrin-dependent endocytosis pathway

Mycoplasma bovis causes chronic arthritis in cattle, accompanied by a severe inflammatory reaction of the joints. Recent studies demonstrated that M. bovis can invade bovine non-phagocytic cells, but the mechanism of M. bovis internalization in the cells remains unclear. In this study, we examined the mechanism by which M. bovis invades synovial cells, including the pathway of cell invasion. Using fluorescence and electron microscopy, multiple M. bovis were observed to adhere to and be internalized in cultured bovine synovial cells. The number of M. bovis colocalized with clathrin heavy chain (CLTC) per cell was significantly higher than the number of M. bovis colocalized with caveolin-1 (Cav-1). The internalized ratio of M. bovis in synovial cells treated with clathrin-dependent endocytosis inhibitor and small interfering RNA (siRNA) against CLTC was significantly lower than that in control cells. In contrast, the internalized ratio of M. bovis in synovial cells was unaffected by siRNA against Cav-1. These findings provide the first evidence that clathrin-dependent endocytosis is one of the major pathways by which M. bovis invades into synovial cells.

Mycoplasma bovis induces matrix metalloproteinase-3 expression in bovine synovial cells via up-regulation of interleukin-1β expression in mononuclear cells

Mycoplasma bovis causes chronic arthritis in calves, presenting as osteolysis in affected joints. Matrix metalloproteinase-3 (MMP-3), an enzyme involved in cartilage degradation, is produced by synovial cells. Production of this proteinase is regulated by interleukin (IL)-1β, which is produced by mononuclear cells. Both factors are known to play important roles in osteolysis in human autoimmune and bacterial arthritis. However, the pathophysiology of Mycoplasma arthritis (MA) has not been elucidated. In this study, we evaluated the levels of MMP-3 and IL-1β in synovial fluid (SF) from MA calves and examined the effect of IL-1β on MMP-3 expression in bovine synovial cells in vitro. Levels of MMP-3 and IL-1β in SF from MA calves were significantly higher than those of clinically healthy calves. Mycoplasma bovis induced significant increases in the expression of IL-1β mRNA and protein in mononuclear cells, compared with cells not exposed to M. bovis. Interestingly, the supernatant of mononuclear cells stimulated with M. bovis contained high levels of IL-1β, which induced higher expression of MMP-3 mRNA and protein in synovial cells than direct stimulation by M. bovis. Recombinant bovine IL-1β also induced increased MMP-3 mRNA and protein expression in synovial cells. Our results indicate that M. bovis induces IL-1β expression by bovine mononuclear cells, and this cytokine then promotes MMP-3 production by synovial cells. These findings suggest that MMP-3 and IL-1β are key factors in the development of osteolysis in MA calves.