Human umbilical cord mesenchymal stem cells alleviate ongoing autoimmune dacryoadenitis in rabbits via polarizing macrophages into an anti-inflammatory phenotype

Umbilical cord mesenchymal stem cells: A powerful fighter against colon cancer?

Colon cancer (CC) stands as one of the most common malignancies related to the gastrointestinal system, whose increasing incidence and death rates have been reported all over the world. Standard treatments for fighting cancers like CC comprise surgical approaches, chemotherapy, and radiotherapy, which are suggested by clinicians according to patients' conditions and disease stages. However, patients who utilize these modalities may suffer from serious side effects and adverse outcomes, for example, toxicity and tumor recurrence, as well as a low 5-year survival rate. The present shreds of evidence showed that mesenchymal stem cells (MSCs) can have a suitable capacity for treating different health problems, especially neoplasms. These multipotent stem cells can be isolated from several sources, such as the umbilical cord, bone marrow, adipose tissue, and placenta. Among these mesenchymal sources, umbilical cord-MSCs have gathered much attention in scientific societies due to their advantages (e.g., low immunogenicity, lack of ethical problems, and easy collection). These days, the efficacy of umbilical cord-MSCs and umbilical cord-MSCs-based strategies, such as conditioned medium, extracellular vesicles, and exosomes, on CC have been explored, and promising findings have been stated. Therefore, in this review, we aimed to summarize and debate evidence regarding the effects of UC-MSCs and their related products on CC with a focus on molecular and cellular mechanisms involved in its treatment and pathogenesis of this malignant tumor.

Pioglitazone alleviates lacrimal gland impairments induced by high-fat diet by suppressing M1 polarization

A high-fat diet (HFD) contributes to the pathogenesis of various inflammatory and metabolic diseases. Previous research confirms that under HFD conditions, the extraorbital lacrimal glands (ELGs) can be impaired, with significant infiltration of pro-inflammatory macrophages (Mps). However, the relationship between HFD and Mps polarization in the ELGs remains unexplored. We first identified and validated the differential expression of PPAR-γ in murine ELGs fed ND and HFD through RNA sequencing. Tear secretion was measured using the Schirmer test. Lipid droplet deposition within the ELGs was observed through Oil Red O staining and transmission electron microscopy. Mps phenotypes were determined through quantitative RT-PCR, immunofluorescence, and flow cytometric analysis. An in vitro high-fat culture system for Mps was established using palmitic acid (PA), with supernatants collected for co-culture with lacrimal gland acinar cells. Gene expression was determined through ELISA, immunofluorescence, immunohistochemistry, quantitative RT-PCR, and Western blot analysis. Pioglitazone reduced M1-predominant infiltration induced by HFD by increasing PPAR-γ levels in ELGs, thereby alleviating lipid deposition and enhancing tear secretion. In vitro tests indicated that PPAR-γ agonist shifted Mps from M1-predominant to M2-predominant phenotype in PA-induced Mps, reducing lipid synthesis in LGACs and promoting lipid catabolism, thus alleviating lipid metabolic disorders within ELGs. Conversely, the PPAR-γ antagonist induced opposite effects. In summary, the lacrimal gland is highly sensitive to high-fat and lipid metabolic disorders. Downregulation of PPAR-γ expression in ELGs induces Mps polarization toward predominantly M1 phenotype, leading to lipid metabolic disorder and inflammatory responses via the NF-κb/ERK/JNK/P38 pathway.

Advances in cellular and molecular pathways of salivary gland damage in Sjögren's syndrome

Sjögren's Syndrome (SS) is an autoimmune disorder characterized by dysfunction of exocrine glands. Primarily affected are the salivary glands, which exhibit the most frequent pathological changes. The pathogenesis involves susceptibility genes, non-genetic factors such as infections, immune cells-including T and B cells, macrophage, dendritic cells, and salivary gland epithelial cells. Inflammatory mediators such as autoantibodies, cytokines, and chemokines also play a critical role. Key signaling pathways activated include IFN, TLR, BAFF/BAFF-R, PI3K/Akt/mTOR, among others. Comprehensive understanding of these mechanisms is crucial for developing targeted therapeutic interventions. Thus, this study explores the cellular and molecular mechanisms underlying SS-related salivary gland damage, aiming to propose novel targeted therapeutic approaches.

Developing a model for aqueous deficient dry eye secondary to periglandular cicatrizing conjunctivitis

PURPOSE

The current study used various techniques to develop a rabbit animal model of lacrimal gland damage caused by scarring conjunctivitis in the periglandular area.

METHODS

Left eyes of New Zealand white rabbits were injected with 0.1 ml of 1M NaOH subconjunctivally around superior and inferior lacrimal gland orifices (Group 1, n = 4), touched with 1M NaOH for 100 s to the superior and inferior fornices with conjunctival denuding (Group 2; n = 4), and electrocauterization to the ductal opening area (Group 3; n = 4). The ocular surface staining, Schirmer I, lacrimal gland, and conjunctival changes were observed at baseline,1, 4, 8, and 12 weeks. The degree of glandular inflammation, conjunctival fibrosis (Masson Trichrome), and goblet cell density (PAS) were also assessed.

RESULTS

At 12 weeks, the lacrimal glands of group 1 rabbits with periglandular injection showed severe inflammation with mean four foci/10HPF and a significant mean reduction in the Schirmer values by 7.6 mm (P = 0.007). Lacrimal glands had diffuse acinar atrophy, loss of myoepithelial cells, and ductular dilatation. The overlying conjunctiva showed fibrosis, goblet cell loss, and corneal vascularization in the inferotemporal quadrant. No lacrimal gland or ocular surface changes were observed in groups 2 and 3 at 12 weeks, except for localized subconjunctival fibrosis.

CONCLUSION

Periglandular injection of 0.1 ml of 1M NaOH induced extensive lacrimal gland damage with reduced secretion and scarring in the subconjunctival plane compared to direct cauterization or direct NaOH contact to the ductal orifices of the rabbit lacrimal gland.

AS101 regulates the Teff/Treg balance to alleviate rabbit autoimmune dacryoadenitis through modulating NFATc2

Sjögren's syndrome (SS) dry eye can cause ocular surface inflammation and lacrimal gland (LG) damage, leading to discomfort and potential vision problems. The existing treatment options for SS dry eye are currently constrained. We investigated the possible therapeutic effect and the underlying mechanism of AS101 in autoimmune dry eye. AS101 was injected subconjunctivally into a rabbit model of autoimmune dacryoadenitis and its therapeutic effects were determined by evaluating clinical and histological scores. The expressions of effector T cells (Teff)/regulatory T cells (Treg)-related transcription factors and cytokines, inflammation mediators, and transcription factor NFATc2 were measured by quantitative real-time PCR and/or Western blot both in vivo and in vitro. Additionally, the role of NFATc2 in the immunomodulatory effects of AS101 on T cells was explored by co-culturing activated peripheral blood lymphocytes (PBLs) transfected with NFATc2 overexpression lentiviral plasmid with AS101. AS101 treatment potently ameliorated the clinical severity and reduced the inflammation of LG. Further investigation revealed that AS101 treatment led to decreased expression of Th1-related genes (T-bet and IFN-γ) and Th17-related genes (RORC, IL-17A, IL-17F, and GM-CSF) and increased expression of Treg-related gene Foxp3 in vivo and in vitro. Meanwhile, AS101 suppressed the expression of TNF-α, IL-1β, IL-23, IL-6, MMP-2, and MMP-9. Mechanistically, AS101 downregulated the expression of NFATc2 in inflamed LGs. Overexpression of NFATc2 in activated PBLs partially blunted the effect of AS101 on Teff suppression and Treg promotion. In conclusion, AS101 is a potential regulator of Teff/Treg cell balance and could be an effective treatment agent for SS dry eye.

The role of M1/M2 macrophage polarization in primary Sjogren's syndrome

BACKGROUND

The purpose of this study was to investigate the role of macrophage polarization in the pathogenesis of primary Sjogren's syndrome (pSS).

METHODS

Peripheral venous blood samples were collected from 30 patients with pSS and 30 healthy controls. Minor salivary gland samples were abtainted from 10 of these patients and 10 non-pSS controls whose minor salivary gland didn't fulfill the classification criteria for pSS. Enzyme-linked immuno sorbent assay was used to examine the serum concentration of M1/M2 macrophage related cytokines (TNF-a, IL-6, IL-23, IL-4, IL-10 and TGF-β). Flow cytometry was used to examine the numbers of CD86+ M1 macrophages and CD206+ M2 macrophages in peripheral blood mononuclear cells (PBMCs). Immunofluorescence was used to test the infiltration of macrophages in minor salivary glands.

RESULTS

This study observed a significant increase in pSS patients both in the numbers of M1 macrophages in peripheral blood and serum levels of M1-related pro-inflammatory cytokines (IL-6, IL-23 and TNF-α). Conversely, M2 macrophages were downregulated in the peripheral blood of pSS patients. Similarly, in the minor salivary glands of pSS patients, the expression of M1 macrophages was increased, and that of M2 macrophages was decreased. Furthermore, a significantly positive correlation was found between the proportions of M1 macrophages in PBMCs and serum levels of IgG and RF.

CONCLUSIONS

This study reveals the presence of an significant imbalance in M1/M2 macrophages in pSS patients. The M1 polarization of macrophages may play an central role in the pathogenesis of pSS.

Current Advances in Regenerative Strategies for Dry Eye Diseases: A Comprehensive Review

Dry eye disease (DED) is an emerging health issue affecting millions of individuals annually. Ocular surface disorders, such as DED, are characterized by inflammation triggered by various factors. This condition can lead to tear deficiencies, resulting in the desiccation of the ocular surface, corneal ulceration/perforation, increased susceptibility to infections, and a higher risk of severe visual impairment and blindness. Currently, the clinical management of DED primarily relies on supportive and palliative measures, including the frequent and lifelong use of different lubricating agents. While some advancements like punctal plugs, non-steroidal anti-inflammatory drugs, and salivary gland autografts have been attempted, they have shown limited effectiveness. Recently, there have been promising developments in the treatment of DED, including biomaterials such as nano-systems, hydrogels, and contact lenses for drug delivery, cell-based therapies, biological approaches, and tissue-based regenerative therapy. This article specifically explores the different strategies reported so far for treating DED. The aim is to discuss their potential as long-term cures for DED while also considering the factors that limit their feasibility and effectiveness. These advancements offer hope for more effective and sustainable treatment options in the future.

Characterisation of macrophage infiltration and polarisation based on integrated transcriptomic and histological analyses in Primary Sjögren's syndrome

Background

Primary Sjögren's syndrome (pSS) is a progressive inflammatory autoimmune disease. Immune cell infiltration into glandular lobules and ducts and glandular destruction are the pathophysiological hallmarks of pSS. Macrophages are one of the most important cells involved in the induction and regulation of an inflammatory microenvironment. Although studies have reported that an abnormal tissue microenvironment alters the metabolic reprogramming and polarisation status of macrophages, the mechanisms driving macrophage infiltration and polarisation in pSS remain unclear.

Methods

Immune cell subsets were characterised using the single-cell RNA sequencing (scRNA-seq) data of peripheral blood mononuclear cells (PBMCs) from patients with pSS (n = 5) and healthy individuals (n = 5) in a public dataset. To evaluate macrophage infiltration and polarisation in target tissues, labial salivary gland biopsy tissues were subjected to histological staining and bulk RNA-seq (pSS samples, n = 24; non-pSS samples, n = 12). RNA-seq data were analysed for the construction of macrophage co-expression modules, enrichment of biological processes and deconvolution-based screening of immune cell types.

Results

Detailed mapping of PBMCs using scRNA-seq revealed five major immune cell subsets in pSS, namely, T cells, B cells, natural killer (NK) cells, dendritic cells (DCs) and monocyte-macrophages. The monocyte-macrophage subset was large and had strong inflammatory gene signatures. This subset was found to play an important role in the generation of reactive oxygen species and communicate with other innate and adaptive immune cells. Histological staining revealed that the number of tissue-resident macrophages was high in damaged glandular tissues, with the cells persistently surrounding the tissues. Analysis of RNA-seq data using multiple algorithms demonstrated that the high abundance of pro-inflammatory M1 macrophages was accompanied by the high abundance of other infiltrating immune cells, senescence-associated secretory phenotype and evident metabolic reprogramming.

Conclusion

Macrophages are among the most abundant innate immune cells in PBMCs and glandular tissues in patients with pSS. A bidirectional relationship exists between macrophage polarisation and the inflammatory microenvironment, which may serve as a therapeutic target for pSS.

Mesenchymal Stromal Cells Regulate M1/M2 Macrophage Polarization in Mice with Immune Thrombocytopenia

Mesenchymal stromal cells have shown promising effects in the treatment of immune thrombocytopenia. However, the underlying mechanisms are not fully understood. In this study, we investigated the therapeutic effects of human bone marrow mesenchymal stromal cells (hBMSCs) and analyzed their unique role in regulating the M1/M2 macrophage ratio. We established a passive immune thrombocytopenia (ITP) mouse model and showed that there was a significant M1/M2 imbalance in ITP model mice by assessing the M1/M2 ratios in the liver, spleen, and bone marrow; we observed excessive activation of M1 cells and decreased M2 cell numbers in vivo. We have shown that systemic infusion of hBMSCs effectively elevated platelet levels after disease onset. Further analysis revealed that hBMSCs treatment significantly suppressed the number of proinflammatory M1 macrophages and enhanced the number of anti-inflammatory M2 macrophages; in addition, the levels of proinflammatory factors, such as interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), were significantly decreased in vivo, while the levels of the anti-inflammatory factor interleukin-10 (IL-10) were increased. In conclusion, our data suggest that hBMSCs treatment can effectively increase platelet counts, and the mechanism is related to the induction of macrophage polarization toward the anti-inflammatory M2 phenotype and the decrease in proinflammatory cytokine production, which together ameliorate innate immune disorders.

Regulatory Mechanism of M1/M2 Macrophage Polarization in the Development of Autoimmune Diseases

Macrophages are innate immune cells in the organism and can be found in almost tissues and organs. They are highly plastic and heterogeneous cells and can participate in the immune response, thereby playing a crucial role in maintaining the immune homeostasis of the body. It is well known that undifferentiated macrophages can polarize into classically activated macrophages (M1 macrophages) and alternatively activated macrophages (M2 macrophages) under different microenvironmental conditions. The directions of macrophage polarization can be regulated by a series of factors, including interferon, lipopolysaccharide, interleukin, and noncoding RNAs. To elucidate the role of macrophages in various autoimmune diseases, we searched the literature on macrophages with the PubMed database. Search terms are as follows: macrophages, polarization, signaling pathways, noncoding RNA, inflammation, autoimmune diseases, systemic lupus erythematosus, rheumatoid arthritis, lupus nephritis, Sjogren's syndrome, Guillain-Barré syndrome, and multiple sclerosis. In the present study, we summarize the role of macrophage polarization in common autoimmune diseases. In addition, we also summarize the features and recent advances with a particular focus on the immunotherapeutic potential of macrophage polarization in autoimmune diseases and the potentially effective therapeutic targets.

Timing of Mesenchymal Stromal Cell Therapy Defines its Immunosuppressive Effects in a Rat Lung Transplantation Model

Cell therapy using mesenchymal stromal cells (MSCs) is being studied for its immunosuppressive effects. In organ transplantation, the amount of MSCs that accumulate in transplanted organs and other organs may differ depending on administration timing, which may impact their immunosuppressive effects. In vitro, adipose-derived mesenchymal stem cells (ADMSCs) suppress lymphocyte activation under cell-to-cell contact conditions. However, in vivo, it is controversial whether ADMSCs are more effective in accumulating in transplanted organs or in secondary lymphoid organs. Herein, we aimed to investigate whether the timing of ADMSC administration affects its immunosuppression ability in a rat lung transplantation model. In the transplantation study, rats were intramuscularly administered half the usual dose of tacrolimus (0.5 mg/kg) every 24 h after lung transplantation. ADMSCs (1 × 106) were administered via the jugular vein before (PreTx) or after (PostTx) transplantation. Cell tracking using quantum dots was performed. ADMSCs accumulated predominantly in the lung and liver; fewer ADMSCs were distributed in the grafted lung in the PreTx group than in the PostTx group. The rejection rate was remarkably low in the ADMSC-administered groups, particularly in the PostTx group. Serum tumor necrosis factor-α (TNF-α), interferon-γ, and interleukin (IL)-6 levels showed a greater tendency to decrease in the PreTx group than in the PostTx group. The proportion of regulatory T cells in the grafted lung 10 days after transplantation was higher in the PostTx group than in the PreTx group. PostTx administration suppresses rejection better than PreTx administration, possibly due to regulatory T cell induction by ADMSCs accumulated in the transplanted lungs, suggesting a mechanism different from that in heart or kidney transplantation that PreTx administration is more effective than PostTx administration. These results could help establish cell therapy using MSCs in lung transplantation.

Novel drug delivery systems for the management of dry eye

Dry eye disease (DED) is a frequently observed eye complaint, which has recently attracted considerable research interest. Conventional therapy for DED involves the use of artificial tear products, cyclosporin, corticosteroids, mucin secretagogues, antibiotics and nonsteroidal anti-inflammatory drugs. In addition, ocular drug delivery systems based on nanotechnology are currently the focus of significant research effort and several nanotherapeutics, such as nanoemulsions, nanosuspensions, microemulsions, liposomes and nanomicelles, are in clinical trials and some have FDA approval as novel treatments for DED. Thus, there has been remarkable progress in the design of nanotechnology-based approaches to overcome the limitations of ophthalmic formulations for the management of anterior eye diseases. This review presents research results on diagnostic methods for DED, current treatment options, and promising pharmaceuticals as future therapeutics, as well as new ocular drug delivery systems.

Mesenchymal Stromal Cell-Based Therapy for Dry Eye: Current Status and Future Perspectives

Dry eye is one of the most common chronic diseases in ophthalmology. It affects quality of life and has become a public health problem that cannot be ignored. The current treatment methods mainly include artificial tear replacement therapy, anti-inflammatory therapy, and local immunosuppressive therapy. These treatments are mainly limited to improvement of ocular surface discomfort and other symptoms. In recent years, regenerative medicine has developed rapidly, and ophthalmologists are working on new methods to treat dry eye. Mesenchymal stromal cells (MSCs) have anti-inflammatory, tissue repair, and immune regulatory effects, and have become a promising tool for the treatment of dry eye. These effects can also be produced by MSC-derived exosomes (MSC-Exos). As a cell-free therapy, MSC-Exos are hypoimmunogenic, serve more stable entities, and compared with MSCs, reduce the safety risks associated with the injection of live cells. This article reviews current knowledge about MSCs and MSC-Exos, and highlights the latest progress and future prospects of MSC-based therapy in dry eye treatment.

Corneal Regeneration Using Adipose-Derived Mesenchymal Stem Cells

Adipose-derived stem cells are a subtype of mesenchymal stem cell that offers the important advantage of being easily obtained (in an autologous manner) from low invasive procedures, rendering a high number of multipotent stem cells with the potential to differentiate into several cellular lineages, to show immunomodulatory properties, and to promote tissue regeneration by a paracrine action through the secretion of extracellular vesicles containing trophic factors. This secretome is currently being investigated as a potential source for a cell-free based regenerative therapy for human tissues, which would significantly reduce the involved costs, risks and law regulations, allowing for a broader application in real clinical practice. In the current article, we will review the existing preclinical and human clinical evidence regarding the use of such adipose-derived mesenchymal stem cells for the regeneration of the three main layers of the human cornea: the epithelium (derived from the surface ectoderm), the stroma (derived from the neural crest mesenchyme), and the endothelium (derived from the neural crest cells).

MSC-Derived Small Extracellular Vesicles Attenuate Autoimmune Dacryoadenitis by Promoting M2 Macrophage Polarization and Inducing Tregs via miR-100-5p

Background

Mesenchymal stem cell-derived small extracellular vesicles (MSC-sEVs) have been increasingly proved as promising immunomodulators against some autoimmune disorders. However, the possible effect and the underlying mechanism of MSC-sEVs in autoimmune dry eye have been rarely studied.

Methods

Small extracellular vesicles from human umbilical cord mesenchymal stem cells (hUC-MSC-sEVs) were subconjunctivally injected to rabbit dry eye model, and their preventive or therapeutical effects were assessed by recording the clinical and histological scores. Quantitative real-time PCR (Q-PCR), western blot and flow cytometry were performed to evaluate the immunomodulatory effects of hUC-MSC-sEVs on macrophages and T regulatory cells (Tregs) both in vivo and in vitro, and the in vitro T cell proliferation was detected by Bromodeoxyuridine (BrdU) assay. In addition, high expression of miR-100-5p in hUC-MSC-sEVs was identified by Q-PCR, and the functional role of sEVs-miR-100-5p on macrophages was explored by a series of co-culture experiments using sEVs derived from hUC-MSCs transfected with miR-100-5p inhibitor.

Results

We firstly demonstrated that hUC-MSC-sEVs had the preventive and therapeutical effects on rabbit autoimmune dacryoadenitis, an animal model of Sjögren’s syndrome (SS) dry eye. Further investigation revealed that hUC-MSC-sEVs administration effectively elicited macrophages into an anti-inflammatory M2 phenotype and elevated the proportion of Tregs both in vivo and in vitro, which contributed to reduced inflammation and improved tissue damage. Importantly, hUC-MSC-sEVs-educated macrophages with M2-like phenotype exhibited strong capacity to inhibit CD4+ T cell proliferation and promote Treg generation in vitro. Mechanistically, miR-100-5p was highly enriched in hUC-MSC-sEVs, and knockdown of miR-100-5p in hUC-MSC-sEVs partially blunted the promotion of hUC-MSC-sEVs on M2 macrophage polarization and even attenuated the effect of hUC-MSC-sEVs-educated macrophages on T cell suppression and Treg expansion.

Conclusion

Our data indicated that hUC-MSC-sEVs alleviated autoimmune dacryoadenitis by promoting M2 macrophage polarization and Treg generation possibly through shuttling miR-100-5p. This study sheds new light on the application of MSC-sEVs as a promising therapeutic method for SS dry eye.

Current trends in pharmaceutical treatment of Dry Eye Disease: A review

Dry eye disease (DED), keratoconjunctivitis sicca or dysfunctional tear syndrome, is the most prevalent ophthalmic disease which affects a substantial segment of people worldwide with increasing frequency. It is considered a multifactorial disease of the ocular surface and tear film, characterized by a variation of signs and symptoms. The symptoms range from mild to severe itching, burning, irritation, eye fatigue, and ocular inflammation that may lead to potential damage to the cornea, conjunctiva and even vision loss. Correspondingly, depending on the different manifestations and pathophysiology, the treatment must be tailored specifically to each patient by targeting the specific mechanisms implicated in their disease. Currently, there are several medical products and techniques available or under investigation for the treatment of DED. The present article focused on the pathophysiology of DED, the new diagnostic approach and the recently developed drug delivery systems or devices reducing the progress of the disease and treating the causes.

Human Umbilical Cord Mesenchymal Stem Cells Improve Locomotor Function in Parkinson’s Disease Mouse Model Through Regulating Intestinal Microorganisms

Parkinson’s disease (PD) is a progressive neurological disorder characterized by loss of neurons that synthesize dopamine, and subsequent impaired movement. Umbilical cord mesenchymal stem cells (UC-MSCs) exerted neuroprotection effects in a rodent model of PD. However, the mechanism underlying UC-MSC-generated neuroprotection was not fully elucidated. In the present study, we found that intranasal administration of UC-MSCs significantly alleviated locomotor deficits and rescued dopaminergic neurons by inhibiting neuroinflammation in a PD mouse model induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, a toxic agent which selectively destroys nigrostriatal neurons but does not affect dopaminergic neurons elsewhere). Furthermore, UC-MSC treatment altered gut microbiota composition characterized by decreased phylum Proteobacteria, class Gammaproteobacteria, family Enterobacteriaceae, and genus Escherichia-Shigella. In addition, the neurotransmitter dopamine in the striatum and 5-hydroxytryptamine in the colon were also modulated by UC-MSCs. Meanwhile, UC-MSCs significantly maintained intestinal goblet cells, which secrete mucus as a mechanical barrier against pathogens. Furthermore, UC-MSCs alleviate the level of TNF-α and IL-6 as well as the conversion of NF-κB expression in the colon, indicating that inflammatory responses were blocked by UC-MSCs. PICRUSt showed that some pathways including bacterial invasion of epithelial cells, fluorobenzoate degradation, and pathogenic Escherichia coli infection were significantly reversed by UC-MSCs. These data suggest that the beneficial effects were detected following UC-MSC intranasal transplantation in MPTP-treated mice. There is a possible neuroprotective role of UC-MSCs in MPTP-induced PD mice by cross talk between the brain and gut.

Human Umbilical Cord Mesenchymal Stem Cells Improve the Necrosis and Osteocyte Apoptosis in Glucocorticoid-Induced Osteonecrosis of the Femoral Head Model through Reducing the Macrophage Polarization

Background and Objectives

Apoptosis is an outstanding determinant of glucocorticoid (GC)-induced osteonecrosis of the femoral head (ONFH). Human umbilical cord mesenchymal stem cells (hUC-MSCs) have been demonstrated to be associated with apoptosis in diseases models. However, the role of hUC-MSCs in GC-induced ONFH via regulating apoptosis still needs further study.

Methods and Results

In the present study, a GC-induced ONFH model was built in vivo through a consecutive injection with lipopolysaccharide (LPS) and methylprednisolone. The necrosis and apoptosis of the femoral head was evaluated by histological and Terminal-deoxynucleoitidyl Transferase Mediated Nick End Labeling (TUNEL) assay. The level of collagen and TRAP positive cells were determined by Masson and TRAP staining, respectively. M1 macrophage polarization was assessed using immunofluorescence assay. The level of proinflammatory cytokines including tumor necrosis factor (TNF)‐α, Interleukin (IL)‐1β and IL-6 of femoral head was determined by enzyme-linked immunosorbent assay (ELISA) kits. The protein expression of AKT, mTOR, p-AKT and p-mTOR was detected using western blot assay. The results showed that hUC-MSCs treatment prominently promoted the GC-induced the decrease of the collagen level and the increase of TRAP positive cells. Besides, hUC-MSCs treatment decreased necrosis and apoptosis, macrophage polarization, the level of TNF‐α, IL‐1β and IL-6, the protein expression of p-AKT and p-mTOR, and the radio of p-AKT to AKT and p-mTOR to mTOR of femoral head in vivo.

Conclusions

Therefore, the present study revealed that hUC-MSCs improved the necrosis and osteocyte apoptosis in GC-induced ONFH model through reducing the macrophage polarization, which was associated with the inhibition of AKT/mTOR signaling pathway.

The link module of human TSG-6 (Link_TSG6) promotes wound healing, suppresses inflammation and improves glandular function in mouse models of Dry Eye Disease

PURPOSE

To investigate the potential of the Link_TSG6 polypeptide comprising the Link module of human TSG-6 (TNF-stimulated gene/protein-6) as a novel treatment for dry eye disease (DED).

METHODS

We analyzed the therapeutic effects of topical application of Link_TSG6 in two murine models of DED, the NOD.B10.H2^b mouse model and the desiccating stress model. The effects of Link_TSG6 on the ocular surface and DED were compared with those of full-length TSG-6 (FL_TSG6) and of 0.05% cyclosporine (Restasis®). Additionally, the direct effect of Link_TSG6 on wound healing of the corneal epithelium was evaluated in a mouse model of corneal epithelial debridement.

RESULTS

Topical Link_TSG6 administration dose-dependently reduced corneal epithelial defects in DED mice while increasing tear production and conjunctival goblet cell density. At the highest dose, no corneal lesions remained in ∼50% of eyes treated. Also, Link_TSG6 significantly suppressed the levels of inflammatory cytokines at the ocular surface and inhibited the infiltration of T cells in the lacrimal glands and draining lymph nodes. Link_TSG6 was more effective in decreasing corneal epithelial defects than an equimolar concentration of FL_TSG6. Link_TSG6 was significantly more potent than Restasis® at ameliorating clinical signs and reducing inflammation. Link_TSG6 markedly and rapidly facilitated epithelial healing in mice with corneal epithelial debridement wounds.

CONCLUSION

Link_TSG6 holds promise as a novel therapeutic agent for DED through its effects on the promotion of corneal epithelial healing and tear secretion, the preservation of conjunctival goblet cells and the suppression of inflammation.

Research progress on inflammatory mechanism of primary Sjögren syndrome

Primary Sjögren syndrome is an autoimmune disease, in which a large number of lymphocytes infiltrate the exocrine glands and cause gland dysfunction. Its pathogenesis is related to the chronic inflammation of the exocrine glands caused by genetic factors, immunodeficiency or viral infection. Long-term inflammation leads to accelerated apoptosis of epithelial cells, disordered gland structure, increased expression of proinflammatory cytokine such as CXC subfamily ligand (CXCL) 12, CXCL13, B cell-activating factor (BAF), interleukin (IL)-6, interferon (IFN)-γ and tumor necrosis factor (TNF)-α in submandibular gland. With the action of antigen-presenting cells such as dendritic cells and macrophages, lymphocytes (mainly B cells) are induced to mature in secondary lymphoid organs and migrate to the submandibular gland to promotes the formation of germinal centers and the synthesis of autoantibodies. Meanwhile, innate lymphocytes, vascular endothelial cells and mucosa-associated constant T cells as important immune cells, also participated in the inflammatory response of the submandibular gland in primary Sjögren syndrome through different mechanisms. This process involves the activation of multiple signal pathways such as JAK/STAT, MAPK/ERK, PI3K/AKT/mTOR, PD-1/PD-L1, TLR/MyD88/NF-κB, BAF/BAF-R and IFN. These signaling pathways interact with each other and are intricately complex, causing lymphocytes to continuously activate and invade the submandibular glands. This article reviews the latest literature to clarify the mechanism of submandibular gland inflammation in primary Sjögren syndrome, and to provide insights for further research.

Role of Innate Immunity in Initiation and Progression of Osteoarthritis, with Emphasis on Horses

Osteoarthritis (OA) is a common condition with diverse etiologies, affecting horses, humans, and companion animals. Importantly, OA is not a single disease, but rather a disease process initiated by different events, including acute trauma, irregular or repetitive overload of articular structures, and spontaneous development with aging. Our understanding of the pathogenesis of OA is still evolving, and OA is increasingly considered a multifactorial disease in which the innate immune system plays a key role in regulating and perpetuating low-grade inflammation, resulting in sustained cartilage injury and destruction. Macrophages within the synovium and synovial fluid are considered the key regulators of immune processes in OA and are capable of both stimulating and suppressing joint inflammation, by responding to local and systemic cues. The purpose of this review is to examine the role of the innate immune system in the overall pathogenesis of OA, drawing on insights from studies in humans, animal models of OA, and from clinical and research studies in horses. This review also discusses the various therapeutic immune modulatory options currently available for managing OA and their mechanisms of action.

Interaction between Macrophages and Human Mesenchymal Stromal Cells Derived from Bone Marrow and Wharton's Jelly-A Comparative Study

Despite intensive clinical research on the use of mesenchymal stromal cells (MSCs), further basic research in this field is still required. Herein, we compared human bone marrow MSCs (BM-MSCs, n = 6) and Wharton’s jelly MSCs (WJ-MSCs, n = 6) in their ability to interact with human primary macrophages. Evaluation of secretory potential revealed that under pro-inflammatory stimulation, WJ-MSCs secreted significantly more IL-6 than BM-MSCs (2-fold). This difference did not translate into the effect of MSCs on macrophages: both types of MSCs significantly directed M1-like macrophages toward the M2 phenotype (based on CD206 expression) to a similar extent. This observation was consistent both in flow cytometry analysis and immunocytochemical assessment. The effect of MSCs on macrophages was sustained when IL-6 signaling was blocked with Tocilizumab. Macrophages, regardless of polarization status, enhanced chemotaxis of both BM-MSCs and WJ-MSCs (p < 0.01; trans-well assay), with WJ-MSCs being significantly more responsive to M1-derived chemotactic signals than BM-MSCs. Furthermore, WJ-MSCs increased their motility (scratch assay) when exposed to macrophage-conditioned medium while BM-MSCs did not. These results indicate that although both BM-MSCs and WJ-MSCs have the ability to reciprocally interact with macrophages, the source of MSCs could slightly but significantly modify the response under clinical settings.

Mesenchymal stromal cells for the treatment of ocular autoimmune diseases

Mesenchymal stromal cells, commonly referred to as MSCs, have emerged as a promising cell-based therapy for a range of autoimmune diseases thanks to several therapeutic advantages. Key among these are: 1) the ability to modulate innate and adaptive immune responses and to promote tissue regeneration, 2) the ease of their isolation from readily accessible tissues and expansion at scale in culture, 3) their low immunogenicity enabling use as an allogeneic "off-the-shelf" product, and 4) MSC therapy's safety and feasibility in humans, as demonstrated in more than one thousand clinical trials. Evidence from preclinical studies and early clinical trials indicate the therapeutic potential of MSCs and their derivatives for efficacy in ocular autoimmune diseases such as autoimmune uveoretinitis and Sjögren's syndrome-related dry eye disease. In this review, we provide an overview of the current understanding of the therapeutic mechanisms of MSCs, and summarize the results from preclinical and clinical studies that have used MSCs or their derivatives for the treatment of ocular autoimmune diseases. We also discuss the challenges to the successful clinical application of MSC therapy, and suggest strategies for overcoming them.

Rabbit models of dry eye disease: Current understanding and unmet needs for translational research

Dry eye disease (DED) is emerging as an eye health pandemic, affecting millions worldwide. The development of novel drugs, drug delivery systems, and targeted therapies for addressing the inflammation in DED necessitates progress in experimental models of DED. Animal models of DED have been created for simulating the two clinically described forms of DED: lacrimal insufficiency and the evaporative DED models. Although most DED models have relied upon rodents, the larger eye size and longer life span of rabbits and the closer resemblance to human lacrimal glands, render rabbits a promising near-ideal model for studying DED. Since the first rabbit DED model was described, numerous modifications including the use of topical epitheliotoxic drugs, neural abolition, activated lymphocytes injection, and surgical dacryoadenectomy have been introduced. The stability of these models, whether short-term or long-term, accordingly guides their experimental or therapeutic utility. A rabbit autoimmune dacryoadenitis model has successfully simulated DED signs and features of lacrimal gland inflammation, as observed in Sjogren's syndrome, that improved with mesenchymal stem cell therapy. This review summarizes the comparative microscopic anatomy of rabbit and human lacrimal glands, various existing rabbit DED models and their respective suitability for understanding pathogenetic mechanism of DED or for experimental drug testing. Also, the insights gained from animal models in dry eye management is described along with the future perspectives. There is still a pressing need of developing rabbit models for studying the pathogenesis of complex ocular surface changes in evaporative and aqueous deficiency DED other than autoimmune dacryoadenitis.

Experimental Pharmacotherapy for Dry Eye Disease: A Review

Dry eye disease (DED) is a complex multifactorial disease showing heterogenous symptoms, including dryness, photophobia, ocular discomfort, irritation and burning but also pain. These symptoms can affect visual function leading to restrictions in daily life activities and reduction in work productivity with a consequently high impact on quality of life. Several pathological mechanisms contribute to the disease: evaporative water loss leads to impairment and loss of tear homeostasis inducing either directly or indirectly to inflammation, in a self-perpetuating vicious cycle. Dysregulated ocular immune responses result in ocular surface damage, which further contributes to DED pathogenesis. Currently, DED treatment is based on a flexible stepwise approach to identify the most beneficial intervention. Although most of the available treatments may control to a certain extent some signs and symptoms of DED, they show significant limitations and do not completely address the needs of patients suffering from DED. This review provides an overview of the emerging experimental therapies for DED. Several promising therapeutic strategies are under development with the aim of dampening inflammation and restoring the homeostasis of the ocular surface microenvironment. Results from early phase clinical trials, testing the effects of EnaC blockers, TRPM8 agonist or mesenchymal stem cells in DED patients, are especially awaited to demonstrate their therapeutic value for the treatment of DED. Moreover, the most advanced experimental strategies in the pipeline for DED, tivanisiran, IL-1R antagonist EBI-005 and SkQ1, are being tested in Phase III clinical trials, still ongoing. Nevertheless, although promising results, further studies are still needed to confirm efficacy and safety of the new emerging therapies for DED.

The therapeutic applications of mesenchymal stromal cells from human perinatal tissues in autoimmune diseases

The autoimmune diseases are characterized by overactivation of immune cells, chronic inflammation, and immune response to self-antigens, leading to the damage and dysfunction of multiple organs. Patients still do not receive desired clinical outcomes while suffer from various adverse effects imparted by current therapies. The therapeutic strategies based on mesenchymal stromal cell (MSC) transplantation have become the promising approach for the treatment of autoimmune diseases due to the immunomodulation property of MSCs. MSCs derived from perinatal tissues are collectively known as perinatal MSCs (PMSCs), which can be obtained via painless procedures from donors with lower risk of being contaminated by viruses than those MSCs from adult tissue sources. Therefore, PMSCs may be the ideal cell source for the treatment of autoimmune diseases. This article summarizes recent progress and possible mechanisms of PMSCs in treating autoimmune diseases in animal experiments and clinical studies. This review also presents existing challenges and proposes solutions, which may provide new hints on PMSC transplantation as a therapeutic strategy for the treatment of autoimmune diseases.

MicroRNA expression profile of Lacrimal Glands in rabbit autoimmune dacryoadenitis model

Purpose: To identify the differential expression of microRNAs (miRs) and the related gene networks and signal pathways in lacrimal glands (LGs) of rabbit autoimmune dacryoadenitis. Methods: Autoimmune dacryoadenitis in rabbits was induced by transferring activated peripheral blood lymphocytes (PBLs). The LGs of normal and model group rabbits were collected for small RNA sequencing. The most differentially expressed miRs were validated by quantitative real time-polymerase chain reaction (qRT-PCR). Further, bioinformatics analysis including target gene prediction, Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed. Results: A total of 15 miRs were differentially expressed in the LGs of rabbit autoimmune dacryoadenitis relative to normal controls. GO and KEGG analysis revealed that most target genes of these dysregulated miRs were implicated in MAPK signaling pathway. Conclusion: Our results showed for the first time the differentially expressed miRs and the related pathways involved in the pathogenesis of rabbit autoimmune dacryoadenitis. These results may contribute to elucidating molecular pathogenesis of Sjögren's syndrome (SS) dry eye.