Fibroblasts with high matrix metalloproteinase 2 expression regulate CD8+ T-cell residency and inflammation via CD100 in psoriasis

BACKGROUND

Psoriasis is a T cell-mediated chronic inflammatory skin condition characterized by the interaction of T cells with various cell types, forming an inflammatory microenvironment that sustains psoriatic inflammation. Homeostasis of these tissue-resident T cells is supported by fibroblasts, the primary structural cells in the dermis. In psoriasis, there is increased expression of matrix metalloproteinase 2 (MMP2), mediating structural alterations in skin tissues and modulating inflammation. Additionally, the CD100-plexin-B2 (PLXNB2) axis is known to enhance psoriasis inflammation via keratinocytes, and CD103 levels are associated with the severity of psoriasis upon relapse.

OBJECTIVES

To elucidate the role of fibroblasts and the MMP2-CD100 axis in modulating psoriasis inflammation.

METHODS

CD100 expression and function in psoriasis were assessed using immunofluorescence, enzyme-linked immunosorbent assay, single-cell transcriptome sequencing, cellular interaction analyses and quantitative reverse transcriptase polymerase chain reaction. CD8+ T cells from people with psoriasis were isolated using magnetic beads, to investigate the regulatory effect of MMP2 on CD100 expression on their membranes. Single-cell transcriptome sequencing, spatial transcriptome sequencing, mimetic timing analysis, immunofluorescence and flow cytometry were used to determine the origin of MMP2 and its impact on CD103+ CD8+ T cells. The hypotheses were further validated in vivo using MMP2 and CD100 inhibitors.

RESULTS

Soluble CD100 (sCD100) was significantly upregulated in both psoriatic lesions and peripheral blood, amplifying psoriasis inflammation by promoting the production of inflammatory cytokines by keratinocytes, fibroblasts and endothelial cells via the sCD100-PLXNB2 axis. Fibroblasts that highly expressed MMP2 (MMP2hi) exacerbated psoriasis symptoms by facilitating CD100 shedding from CD8+ T-cell membranes. Additionally, it was shown that fibroblasts enhance the upregulation of the CD8+ T-cell residency factor CD103 in co-cultures with CD8+ T cells. Inhibitors targeting MMP2 and CD100 were effective in reducing inflammation in an imiquimod-induced psoriasis model.

CONCLUSIONS

Our findings underscore the pivotal role of MMP2hi fibroblasts in the amplification and recurrence of inflammatory responses in psoriasis. These fibroblasts augment psoriasis inflammation through the CD100-PLXNB2 axis by facilitating CD100 shedding on CD8+ T-cell membranes and by upregulating CD103, thereby enhancing CD8+ T-cell residency.

Autoinducer-2 produced by oral microbial flora and alveolar bone loss in periodontitis

OBJECTIVE

The aim of this study was to investigate the association between autoinducer-2 (AI-2) of oral microbial flora and the alveolar bone destruction in periodontitis to determine if AI-2 may have the potential that monitor periodontitis and predict bone loss.

BACKGROUND

Plaque biofilm was the initiating factor of periodontitis and the essential factor of periodontal tissue destruction. The formation of biofilms depended on the complex regulation of the quorum sensing (QS) system, in which bacteria could sense changes in surrounding bacterial density by secreting the autoinducer (AI) to regulate the corresponding physiological function. Most oral bacteria also communicated with each other to form biofilms administrating the QS system, which implied that the QS system of periodontal pathogens was related to periodontitis, but the specific relationship was unknown.

METHOD

We collected the gingival crevicular fluid (GCF) samples and measured the concentration of AI-2 in samples using the Vibrio harveyi BB180 bioluminescent-reporter system. To explore the interaction between AI-2 and bone metabolism, we utilized AI-2 purified from Fusobacterium nucleatum to investigate the impact of F. nucleatum AI-2 on osteoclast differentiation. Moreover, we constructed murine periodontitis models and multi-species biofilm models to study the association between AI-2 and periodontal disease progression.

RESULTS

The AI-2 concentration in GCF samples increased along with periodontal disease progression (p < .0001). F. nucleatum AI-2 promoted osteoclast differentiation in a dose-dependent manner. In the periodontitis mice model, the CEJ-ABC distance in the F. nucleatum AI-2 treatment group was higher than that in the simple ligation group (p < .01), and the maxilla of the mice in the group exhibited significantly lower BMD and BV/TV values (p < .05).

CONCLUSIONS

We demonstrated that the AI-2 concentration varied with the alveolar bone destruction in periodontitis, and it may have the potential for screening periodontitis. F. nucleatum AI-2 promoted osteoclast differentiation in a dose-dependent manner and aggravated bone loss.

Comparative evaluation of semaphorin-4D, peptidylarginine deiminase-2, and matrix metalloproteinase-8 levels of gingival crevicular fluid in periodontally healthy and Stage III periodontitis smoker and non-smoker patients before and after non-surgical periodontal therapy

BACKGROUND

This study was designed to assess the influence of non-surgical periodontal therapy (NSPT) on gingival crevicular fluid (GCF) levels of semaphorin-4D (SEMA-4D), peptidylarginine deiminase-2 (PAD-2), and matrix metalloproteinase-8 (MMP-8) levels in periodontally healthy, Stage III periodontitis non-smoker and smoker patients.

METHODS

Sixty patients were equally divided into three groups, Group I: Periodontally healthy, Group II: Non-smokers with Stage III periodontitis, and Group III: Smokers with Stage III periodontitis. The patients underwent NSPT with clinical and biochemical parameters examined at baseline and 3 months post therapy. GCF was collected for levels of SEMA-4D, PAD-2, and MMP-8 through enzyme-linked immunosorbent assay (ELISA).

RESULTS

Greater values of PPD (8.06 ± 0.19 mm), CAL (8.94 ± 0.19 mm), PI (2.58 ± 0.19) while lower PBI (1.39 ± 0.19%) and GI (1.72 ± 0.19) scores were seen in Group III as compared to Group II, which reduced significantly from baseline to 3 months in both the groups after NSPT. Minimum values of SEMA-4D, PAD-2, and MMP-8 levels in GCF were seen for Group I, which increased incrementally to Group II and III. Also, among Group II and III the SEMA-4D, PAD-2, and MMP-8 levels in GCF reduced from baseline to 3 months indicating a favorable response within the tissues.

CONCLUSION

Greater levels in GCF of Levels of SEMA-4D, PAD-2, and MMP-8 in Group II and III, which reduced significantly post NSPT, implied that these biomarkers play a pivotal role in the inflammatory process and can be utilized for early diagnosis.

Sema4D is diminished in leukocyte platelet-rich fibrin and impairs pre-osteoblastic MC3T3-E1 cells' functionality

OBJECTIVE

Semaphorin 4D (Sema4D) is a coupling factor expressed on osteoclasts that may hinder osteoblast differentiation. Since the leukocyte platelet-rich fibrin (L-PRF) membrane promotes growth factor concentration, this study aims to quantify the amount of Sema4D in L-PRF membranes, and analyze the impact of Sema4D on osteoblast cell function in vitro.

DESIGN

Enzyme-linked immunosorbent assay (ELISA) was used to quantify the levels of Sema4D in both L-PRF and whole blood (serum). To analyze the impairment of Sema4D on osteoblasts, MC3T3-E1 cells were induced to osteogenic differentiation and exposed to Sema4D ranging from 10 to 500 ng/ml concentrations. The following parameters were assayed: 1) cell viability by MTT assay after 24, 48, and 72 h; 2) matrix mineralization by Alizarin Red staining after 14 days, 3) Runt-related transcription factor 2 (RUNX-2), osteocalcin (OCN), osteonectin (ONC), bone sialoprotein (BSP) and alkaline phosphatase (ALP) gene expression by qPCR. For all data, the significance level was set at 5%.

RESULTS

The amount of Sema4D in the whole blood (serum) was higher than in L-PRF. Osteoblasts exposed to Sema4D at all tested concentrations exhibited a decrease in matrix mineralization formation as well in RUNX-2, OCN, ONC, BSP, and ALP gene expression (p < 0.05).

CONCLUSION

The presence of Sema4D, a molecule known for suppressing osteoblast activity, diminishes within L-PRF, enhancing its ability to facilitate bone regeneration.

Soluble Sema4D cleaved from osteoclast precursors by TACE suppresses osteoblastogenesis

Bone remodelling is mediated by orchestrated communication between osteoclasts and osteoblasts which, in part, is regulated by coupling and anti-coupling factors. Amongst formally known anti-coupling factors, Semaphorin 4D (Sema4D), produced by osteoclasts, plays a key role in downmodulating osteoblastogenesis. Sema4D is produced in both membrane-bound and soluble forms; however, the mechanism responsible for producing sSema4D from osteoclasts is unknown. Sema4D, TACE and MT1-MMP are all expressed on the surface of RANKL-primed osteoclast precursors. However, only Sema4D and TACE were colocalized, not Sema4D and MT1-MMP. When TACE and MT1-MMP were either chemically inhibited or suppressed by siRNA, TACE was found to be more engaged in shedding Sema4D. Anti-TACE-mAb inhibited sSema4D release from osteoclast precursors by ~90%. Supernatant collected from osteoclast precursors (OC-sup) suppressed osteoblastogenesis from MC3T3-E1 cells, as measured by alkaline phosphatase activity, but OC-sup harvested from the osteoclast precursors treated with anti-TACE-mAb restored osteoblastogenesis activity in a manner that compensates for diminished sSema4D. Finally, systemic administration of anti-TACE-mAb downregulated the generation of sSema4D in the mouse model of critical-sized bone defect, whereas local injection of recombinant sSema4D to anti-TACE-mAb-treated defect upregulated local osteoblastogenesis. Therefore, a novel pathway is proposed whereby TACE-mediated shedding of Sema4D expressed on the osteoclast precursors generates functionally active sSema4D to suppress osteoblastogenesis.

Locally Secreted Semaphorin 4D Is Engaged in Both Pathogenic Bone Resorption and Retarded Bone Regeneration in a Ligature-Induced Mouse Model of Periodontitis

It is well known that Semaphorin 4D (Sema4D) inhibits IGF-1-mediated osteogenesis by binding with PlexinB1 expressed on osteoblasts. However, its elevated level in the gingival crevice fluid of periodontitis patients and the broader scope of its activities in the context of potential upregulation of osteoclast-mediated periodontal bone-resorption suggest the need for further investigation of this multifaceted molecule. In short, the pathophysiological role of Sema4D in periodontitis requires further study. Accordingly, attachment of the ligature to the maxillary molar of mice for 7 days induced alveolar bone-resorption accompanied by locally elevated, soluble Sema4D (sSema4D), TNF-α and RANKL. Removal of the ligature induced spontaneous bone regeneration during the following 14 days, which was significantly promoted by anti-Sema4D-mAb administration. Anti-Sema4D-mAb was also suppressed in vitro osteoclastogenesis and pit formation by RANKL-stimulated BMMCs. While anti-Sema4D-mAb downmodulated the bone-resorption induced in mouse periodontitis, it neither affected local production of TNF-α and RANKL nor systemic skeletal bone remodeling. RANKL-induced osteoclastogenesis and resorptive activity were also suppressed by blocking of CD72, but not Plexin B2, suggesting that sSema4D released by osteoclasts promotes osteoclastogenesis via ligation to CD72 receptor. Overall, our data indicated that ssSema4D released by osteoclasts may play a dual function by decreasing bone formation, while upregulating bone-resorption.

Gingival crevicular fluid lipocalin-2 and semaphorin3A in stage III periodontitis: Non-surgical periodontal treatment effects

BACKGROUND AND OBJECTIVE

Identification of biomarkers to assess individual risk and monitor periodontal health status is important. Research on lipocalin-2 (LCN2) and semaphorin3A (Sema3A) is lacking. This study aimed to evaluate gingival crevicular fluid (GCF) LCN2, Sema3A, and tumor necrosis factor-α (TNF-α) levels in periodontally healthy (H), gingivitis (G), and periodontitis (P) patients, and their changes following non-surgical periodontal therapy.

METHODS

Sixty systemically healthy and non-smoker participants, diagnosed as periodontally healthy, gingivitis, and stage III grade C periodontitis, were recruited (n = 20/group). Clinical periodontal parameters were recorded and GCF samples were obtained at baseline from all groups; for group P, these were repeated one and three months following non-surgical periodontal treatment. GCF LCN2, Sema3A, and TNF-α levels were evaluated with enzyme-linked immunosorbent assay.

RESULTS

GCF LCN2, Sema3A, and TNF-α total amounts were significantly higher in disease groups than group H (p < .001). Between P and G groups, only TNF-α levels were significantly different (p < .001). Non-surgical periodontal therapy resulted in significant improvement of all clinical parameters and significant decreases of GCF LCN2 and TNF-α levels, at both time points, compared with baseline (p < .001). Sema3A levels remained unchanged following treatment (p > .05). LCN2 and TNF-α levels were significantly positively correlated with clinical parameters. LCN2 (AUC [area under the curve] = 0.94) and TNF-α (AUC = 0.98) levels were similarly accurate in differentiating between periodontal disease (whether G or P) and healthy controls.

CONCLUSIONS

LCN2 and TNF-α levels in GCF are correlated with clinical parameters and could prove useful as non-invasive screening tools for periodontitis.

The emerging roles of semaphorin4D/CD100 in immunological diseases

In vertebrates, the semaphorin family of proteins is composed of 21 members that are divided into five subfamilies, i.e. classes 3 to 7. Semaphorins play crucial roles in regulating multiple biological processes, such as neural remodeling, tissue regeneration, cancer progression, and, especially, in immunological regulation. Semaphorin 4D (SEMA4D), also known as CD100, is an important member of the semaphorin family and was first characterized as a lymphocyte-specific marker. SEMA4D has diverse effects on immunologic processes, including immune cell proliferation, differentiation, activation, and migration, through binding to its specific membrane receptors CD72, PLXNB1, and PLXNB2. Furthermore, SEMA4D and its underlying signaling have been increasingly linked with several immunological diseases. This review focuses on the significant immunoregulatory role of SEMA4D and the associated underlying mechanisms, as well as the potential application of SEMA4D as a diagnostic marker and therapeutic target for the treatment of immunological diseases.