Mobilization of lymphatic endothelial precursor cells and lymphatic neovascularization in primary Sjögren's syndrome

Network pharmacology-based strategy to investigate the mechanisms of artemisinin in treating primary Sjögren's syndrome

OBJECTIVE

The study aimed to explore the mechanism of artemisinin in treating primary Sjögren's syndrome (pSS) based on network pharmacology and experimental validation.

METHODS

Relevant targets of the artemisinin and pSS-related targets were integrated by public databases online. An artemisinin-pSS network was constructed by Cytoscape. The genes of artemisinin regulating pSS were imported into STRING database to construct a protein-protein interaction (PPI) network in order to predict the key targets. The enrichment analyses were performed to predict the crucial mechanism and pathway of artemisinin against pSS. The active component of artemisinin underwent molecular docking with the key proteins. Artemisinin was administered intragastrically to SS-like NOD/Ltj mice to validate the efficacy and critical mechanisms.

RESULTS

Network Pharmacology analysis revealed that artemisinin corresponded to 412 targets, and pSS related to 1495 genes. There were 40 intersection genes between artemisinin and pSS. KEGG indicated that therapeutic effects of artemisinin on pSS involves IL-17 signaling pathway, HIF-1 signaling pathway, apoptosis signaling pathway, Th17 cell differentiation, PI3K-Akt signaling pathway, and MAPK signaling pathway. Molecular docking results further showed that the artemisinin molecule had higher binding energy by combining with the key nodes in IL-17 signaling pathway. In vivo experiments suggested artemisinin can restored salivary gland secretory function and improve the level of glandular damage of NOD/Ltj mice. It contributed to the increase of regulatory T cells (Tregs) and the downregulated secretion of IL-17 in NOD/Ltj model.

CONCLUSION

The treatment of pSS with artemisinin is closely related to modulating the balance of Tregs and Th17 cells via T cell differentiation.

Dysregulation of Lymphatic Endothelial VEGFR3 Signaling in Disease

Vascular endothelial growth factor (VEGF) receptor 3 (VEGFR3), a receptor tyrosine kinase encoded by the FLT4 gene, plays a significant role in the morphogenesis and maintenance of lymphatic vessels. Under both normal and pathologic conditions, VEGF-C and VEGF-D bind VEGFR3 on the surface of lymphatic endothelial cells (LECs) and induce lymphatic proliferation, migration, and survival by activating intracellular PI3K-Akt and MAPK-ERK signaling pathways. Impaired lymphatic function and VEGFR3 signaling has been linked with a myriad of commonly encountered clinical conditions. This review provides a brief overview of intracellular VEGFR3 signaling in LECs and explores examples of dysregulated VEGFR3 signaling in various disease states, including (1) lymphedema, (2) tumor growth and metastasis, (3) obesity and metabolic syndrome, (4) organ transplant rejection, and (5) autoimmune disorders. A more complete understanding of the molecular mechanisms underlying the lymphatic pathology of each disease will allow for the development of novel strategies to treat these chronic and often debilitating illnesses.

Combined use of total glucosides of paeony and hydroxychloroquine in primary Sjögren's syndrome: A systematic review

OBJECTIVE

To assess the effectiveness and safety of the total glucosides of paeony (TGP) combined with hydroxychloroquine (HCQ) on the treatment of primary Sjögren's syndrome (pSS) by conducting a meta-analysis.

METHODS

Eight databases were searched for randomized controlled trials (RCTs) reporting the use of TGP combined with HCQ for pSS, which are before May 10, 2022. Meta-analyses were performed on disappeared clinical symptoms (dry mouth and dry eyes), Schirmer's test, saliva flow test, erythrocyte sedimentation rate (ESR), index of immunoglobulin G (IgG), immunoglobulin M (IgM), immunoglobulin A (IgA), and adverse events (AEs). The Revman 5.4 software was used for this meta-analysis.

RESULTS

Seven RCTs which included 632 participants were identified. The pooled results showed significant differences in clinical symptoms disappear (dry mouth and dry eyes) (p = .0004), IgM (p < .00001), IgA (p < .00001), salivary flow rate (p < .00001) and Schirmer's test (p = .02) in the comparison of TGP combined with HCQ and HCQ alone. For the IgG and ESR, both pooled and subgroup analyses showed that TGP + HCQ was superior to HCQ alone. For the safety analysis, no significant differences in AEs (p = .39) was revealed. The more frequently seen adverse reactions were diarrhea, vomit and there was no severe adverse events were reported in TGP + HCQ group.

CONCLUSION

Therefore, TGP + HCQ can be considered to be a potentially valid and safe combination for the treatment of pSS in the clinic.

The role of Th9 CD4+ T cells and IL-9 during primary Sjogren's syndrome

OBJECTIVE

The objective of this study is to investigate the expression levels of Th₉ CD4⁺ T cells and IL-9 secretion in peripheral blood mononuclear cells of patients with primary Sjogren's syndrome. Further, this study aimed to investigate the role of Th₉ cells in the occurrence and development of pSS.

METHODS

A total of 20 pSS patients and 20 healthy people, matched with age and gender, were selected as the experimental and control group, respectively. Flow cytometry and ELISA were used to detect the expression of Th₉ cytokines in peripheral blood mononuclear cells and IL-9 in serum, respectively. These factors were then correlated to other clinical indicators.

RESULTS

The levels of Th₉ CD4⁺ T cells and IL-9 of pSS patients were significantly higher than those of the control group. Th₉ CD4⁺ T cells and IL-9 levels in peripheral blood of pSS patients were negatively correlated with salivary flow rate, while IL-9 level was positively correlated with globulin. The transcription levels of IL-9 and immune-related genes including IL-4, IL-7, IL-17, SMAD3, STAT5 and JAK3 were dramatically increased in serum of pSS patients.

CONCLUSION

The expression levels of Th₉ in peripheral blood and serum IL-9 of patients with pSS were significantly increased, which were correlated with clinical immunological indexes. Together, these data suggest that Th₉ cells and IL-9 may be involved in the pathogenesis of pSS.

The Relationship between VEGFC Gene Polymorphisms and Autoimmune Thyroiditis

Background

Autoimmune thyroid diseases (AITDs), representative autoimmune diseases, mainly consist of Graves' disease (GD) and Hashimoto's thyroiditis (HT). In this passage, we investigated the association between vascular endothelial growth factor C (VEGFC) gene polymorphisms and AITDs.

Methods

A total of 1084 patients with AITDs and 794 healthy controls were tested for VEGFC gene genotypes in four single nucleotide polymorphisms (SNPs) by high-throughput sequencing, and the correlation between VEGFC gene polymorphisms and AITDs was statistically analyzed.

Results

The genotype distribution of rs3775194 was statistically associated with AITDs compared with the control group. Rs3775194 was associated with AITDs under the overdominant model, both before and after adjusting for confounding factors, while the other three SNPs were not associated with GD and HT. There was a prominent discrepancy between male healthy controls and male AITD patients under overdominant model in rs3775194 and the recessive model in rs11947611. The genotype distribution of rs3775194 was statistically related to male HT.

Conclusion

These results reveal the correlation between VEGFC mutation and AITD susceptibility.

Vascular Endothelial Growth Factor Biology and Its Potential as a Therapeutic Target in Rheumatic Diseases

Rheumatic diseases constitute a diversified group of diseases distinguished by arthritis and often involve other organs. The affected individual has low quality of life, productivity even life-threatening in some severe conditions. Moreover, they impose significant economic and social burdens. In recent years, the patient outcome has been improved significantly due to clearer comprehension of the pathology of rheumatic diseases and the effectiveness of "treat to target" therapies. However, the high cost and the adverse effects are the concerns and full remissions are not often observed. One of the main processes that contributes to the pathogenesis of rheumatic diseases is angiogenesis. Vascular endothelial growth factor (VEGF), a central mediator that regulates angiogenesis, has different isoforms and functions in various physiological processes. Increasing evidence suggests an association between the VEGF system and rheumatic diseases. Anti-VEGF and VEGF receptor (VEGFR) therapies have been used to treat several cancers and eye diseases. This review summarizes the current understanding of VEGF biology and its role in the context of rheumatic diseases, the contribution of VEGF bioavailability in the pathogenesis of rheumatic diseases, and the potential implications of therapeutic approaches targeting VEGF for these diseases.

Increased secretion of VEGF-C from SiO2-induced pulmonary macrophages promotes lymphangiogenesis through the Src/eNOS pathway in silicosis

Silicosis, a type of lung inflammation and fibrosis caused by long-term inhalation of SiO2 particles, lacks effective treatment currently. Based on the results of our previous animal experiments, in lungs of SiO2-induced silicosis rats, a large number of lymphatic vessels are generated in the early stage of inflammation, which is of great significance for the removal of dust and inflammatory mediators. Here, the molecular mechanism of lymphangiogenesis is further studied. Vascular endothelial growth factor (VEGF-C) is a key pro-lymphangiogenic factor, and its elevated expression is closely related to lymphangiogenesis. In this investigation, we demonstrated that the protein level of VEGF-C was differentially expressed in bronchoalveolar lavage fluid (BALF) and alveolar macrophages (AM) in silicosis patients and healthy controls. We further stimulated human monocyte-macrophage line U937 with SiO2, collected the culture supernatants as conditioned medium (CM) for culturing lymphatic endothelial cells (LECs) in vitro, and observed the expression of VEGF-C in the supernatant and its effect on LEC tube formation. The results showed that both CM and single VEGF-C recombinant protein stimulation significantly enhanced LEC proliferation [(1.80 ± 0.18), (1.73 ± 0.16)], chemotaxis [chemotactic cell number (101.40 ± 13.83), (93.40 ± 9.61)], and tube formation [tube number (32.20 ± 7.26), (25.00 ± 6.25); branch number (77.20 ± 6.80), (84.60 ± 7.90)], whereas CM treated with VEGF-CmAb inhibited the proliferation (1.37 ± 0.17), chemotaxis [chemotactic cell number (57.40 ± 8.62)], and tube formation [tube number (7.40 ± 1.85); branch number (47.20 ± 13.44)] of LECs. In addition, CM and VEGF-C can promote the expression of vascular endothelial growth factor receptor 3 (VEGFR-3) and lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1) in LECs, which may further mediate lymphangiogenesis by up-regulating the Src/eNOS downstream signaling molecular pathway. This study is the first to clarify the molecular mechanism of pulmonary lymphangiogenesis in silicosis and may point in the direction of eventual treatments, surveillance, and regulation at a molecular level.

The Involvement of Innate and Adaptive Immunity in the Initiation and Perpetuation of Sjögren's Syndrome

Sjogren’s syndrome (SS) is a chronic autoimmune disease characterized by the infiltration of exocrine glands including salivary and lachrymal glands responsible for the classical dry eyes and mouth symptoms (sicca syndrome). The spectrum of disease manifestations stretches beyond the classical sicca syndrome with systemic manifestations including arthritis, interstitial lung involvement, and neurological involvement. The pathophysiology underlying SS is not well deciphered, but several converging lines of evidence have supported the conjuncture of different factors interplaying together to foster the initiation and perpetuation of the disease. The innate and adaptive immune system play a cardinal role in this process. In this review, we discuss the inherent parts played by both the innate and adaptive immune system in the pathogenesis of SS.

Cellular and Molecular Heterogeneity Associated with Vessel Formation Processes

The microvasculature heterogeneity is a complex subject in vascular biology. The difficulty of building a dynamic and interactive view among the microenvironments, the cellular and molecular heterogeneities, and the basic aspects of the vessel formation processes make the available knowledge largely fragmented. The neovascularisation processes, termed vasculogenesis, angiogenesis, arteriogenesis, and lymphangiogenesis, are important to the formation and proper functioning of organs and tissues both in the embryo and the postnatal period. These processes are intrinsically related to microvascular cells, such as endothelial and mural cells. These cells are able to adjust their activities in response to the metabolic and physiological requirements of the tissues, by displaying a broad plasticity that results in a significant cellular and molecular heterogeneity. In this review, we intend to approach the microvasculature heterogeneity in an integrated view considering the diversity of neovascularisation processes and the cellular and molecular heterogeneity that contribute to microcirculatory homeostasis. For that, we will cover their interactions in the different blood-organ barriers and discuss how they cooperate in an integrated regulatory network that is controlled by specific molecular signatures.

Cytokines as therapeutic targets in primary Sjögren syndrome

Primary Sjögren syndrome (SjS) is a systemic autoimmune disease that may affect 1 in 1000 people (overwhelmingly women) and that can be a serious disease with excess mortality due to severe organ-specific involvements and the development of B cell lymphoma; systemic involvement clearly marks the disease prognosis, and strongly suggests the need for closer follow-up and more robust therapeutic management. Therapy is established according to the organ involved and severity. As a rule, the management of systemic SjS should be organ-specific, with glucocorticoids and immunosuppressive agents limited to potentially-severe involvements; unfortunately, the limited evidence available for these drugs, together with the potential development of serious adverse events, makes solid therapeutic recommendations difficult. The emergence of biological therapies has increased the therapeutic armamentarium available to treat primary SjS. Biologics currently used in SjS patients are used off-label and are overwhelmingly agents targeting B cells, but the most recent studies are moving on into the evaluation of targeting specific cytokines involved in the SjS pathogenesis. The most recent etiopathogenic advances in SjS are shedding some light in the search for new highly-selective biological therapies without the adverse effects of the standard drugs currently used (corticosteroids and immunosuppressant drugs). This review summarizes the potential pharmacotherapeutic options targeting the main cytokine families involved in the etiopathogenesis of primary SjS and analyzes potential insights for developing new therapies.

Comparison and functional characterisation of peripheral blood mononuclear cells isolated from filarial lymphoedema and endemic normals of a South Indian population

OBJECTIVE

The underlying problem in lymphatic filariasis is irreversible swelling of the limbs (lymphoedema), which is a unique feature of lymphatic insufficiency. It is still unclear whether the natural ability of lymphatics to form functional lymphatic vasculature is achieved or attenuated in the lymphoedemal pathology. Clinical studies have clearly shown that circulating lymphatic progenitors (CLPs), a subset of bone marrow-derived mononuclear cells (PBMCs), contribute to post-natal lymph vasculogenesis. CLP-based revascularisation could be a promising strategy to bypass the endothelial disruption and damage incurred by the filarial parasites. Thus our aim was to compare and characterise the functional prowess of PBMCs in physiological and lymphoedemal pathology.

METHODS

PBMCs were isolated from venous blood sample from drug-naive endemic normals (EN) and drug-deprived filarial lymphoedema (FL) individuals using density gradient centrifugation. Adhesion, transwell migration and in vitro matrigel assays were employed to characterise the lymphvasculogenic potential of PBMCs. CLPs were phenotypically characterised using flow cytometry; expression levels of lymphatic markers and inflammatory cytokines were quantified using qRT-PCR and ELISA, respectively.

RESULTS

PBMCs from FL group display poor adherence to fibronectin (P = 0.040), reduced migration towards SDF-1α (P = 0.035), impaired tubular network (P = 0.004) and branching point (P = 0.048) formation. The PBMC mRNA expression of VEGFR3 (P = 0.039) and podoplanin (P = 0.050) was elevated, whereas integrin α9 (P = 0.046) was inhibited in FL individuals; additionally, the surface expression of CD34 (P = 0.048) was significantly reduced in the FL group compared to the EN group.

CONCLUSION

PBMCs from filarial lymphoedema show defective and dysregulated lymphvasculogenic function compared to endemic normals.

Leptin/OB-R pathway promotes IL-4 secretion from B lymphocytes and induces salivary gland epithelial cell apoptosis in Sjögren's syndrome

Sjögren's syndrome (SjS) is a chronic autoimmune epithelitis in which cell apoptosis promotes the formation of inflammatory lesions. We used immunohistochemistry and TUNEL to assay B cell infiltration and apoptosis in salivary gland tissue from 16-week-old NOD/LtJ mice with SjS. In co-cultures of primary salivary glandepithelial cells (SGECs) and spleen B cells, we assessed SGEC viability and apoptosis using CCK8 assays and flow cytometry. ELISAs were employed to assess cytokine levels in culture medium. Leptin protein, leptin receptor (OB-R), pro- and anti-apoptotic proteins, and Jak2/Stat3/ERK signaling molecules were analyzed using western blotting. B cell infiltration and salivary gland apoptosis were increased in salivary tissue from mice with SjS. Leptin treatment had no effect on cell viability or apoptosis among B cells and primary SGECs. B cell and SGEC co-culture systems showed that leptin increased apoptosis induced by B lymphocytes, reduced SGEC cell viability, and promoted IL-4 secretion from B cells. This suggests Leptin/OB-R signaling stimulates B cells-induced SGEC apoptosis via IL-4 secretion and OB-R-Jak2-Stat3 activation.

Lymphatic endothelial progenitors originate from plastic myeloid cells activated by toll-like receptor-4

BACKGROUND

Myeloid-derived lymphatic endothelial cells (M-LECP) are induced by inflammation and play an important role in adult lymphangiogenesis. However, the mechanisms driving M-LECP differentiation are currently unclear. We previously showed that activation of Toll-like receptor-4 (TLR4) induces myeloid-lymphatic transition (MLT) of immortalized mouse myeloid cells. Here the goals were to assess the potential of different TLR4 ligands to induce pro-lymphatic reprogramming in human and mouse primary myeloid cells and to identify transcriptional changes regulating this process.

METHODOLOGY/PRINCIPAL FINDINGS

Human and mouse myeloid cells were reprogrammed to the lymphatic phenotype by TLR4 ligands including lipopolysaccharide (LPS), recombinant high mobility group box 1 protein (HMGB1), and paclitaxel. TLR4 induced similar MLT in cells from mice of different strains and immune status. Commonly induced genes were detected by transcriptional profiling in human and mouse myeloid cells from either immunocompetent or immunodeficient mice. Shared trends included: (1) novel expression of lymphatic-specific markers vascular endothelial growth factor receptor-3 (VEGFR-3), lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1) and podoplanin (PDPN) largely absent prior to induction; (2) lack of notable changes in blood vessel-specific markers; (3) transient expression of VEGFR-3, but sustained increase of vascular endothelial growth factor-C (VEGF-C) and a variety of inflammatory cytokines; (4) dependency of VEGFR-3 upregulation and other LEC genes on NF-κB; and (5) novel expression of lymphatic-specific (e.g., PROX1) and stem/progenitor (e.g., E2F1) transcription factors known for their roles in adult and embryonic vascular formation. M-LECP generated by TLR4 ligands in vitro were functional in vivo as demonstrated by significantly increased lymphatic vessel density and lymphatic metastasis detected in orthotopic breast cancer models.

CONCLUSIONS/SIGNIFICANCE

We established a novel TLR4-dependent protocol for in vitro production of functionally competent M-LECP from primary human or mouse myeloid cells and identified many potential regulators of this process. This information can be further exploited for research and therapeutic purposes.

Insight into pathogenesis of Sjögren's syndrome: Dissection on autoimmune infiltrates and epithelial cells

Sjögren's syndrome (SS) is a chronic autoimmune disease with broad clinical spectrum, extending from benign exocrinopathy to severe systemic disease and lymphoma development. The glandular and extraglandular dysfunction of SS is associated with lymphocytic infiltrates that invade the epithelial structures of affected organs. The in-depth study of autoimmune lesions in the minor salivary glands (MSG), which are the major target-organ of SS responses, revealed that the lymphocytic infiltrates vary in severity and composition among SS-patients, are full-blown at diagnosis and remain unchanged thereafter. Although the pathogenetic pathways underlying SS have not yet elucidated, it is well-established that glandular epithelial cells are central regulators of local autoimmune responses. Moreover, chronic inflammation affects epithelial function and phenotype, which strengthens or weakens their immunoregulatory/secretory function, leading to deterioration of autoimmune phenomena. Herein, the current findings regarding the autoimmune lesions, the role of epithelial cells and their interaction with infiltrating lymphocytic cells are discussed.