Sodium-glucose cotransporter-2 inhibitors and their potential role in dementia onset and cognitive function in patients with diabetes mellitus: a systematic review and meta-analysis.

This systematic review and meta-analysis aimed to determine the association between the use of sodium-glucose cotransporter 2 (SGLT-2) inhibitors and dementia onset as well as cognitive function in patients with diabetes mellitus. We comprehensively searched the MEDLINE, Embase, and CENTRAL databases to select relevant studies published up to August 2023. The use of SGLT-2 inhibitors significantly lowers dementia risk compared to SGLT-2i non-users (Hazard ratio: 0.68, 95 % CI: 0.50-0.92). Furthermore, our findings indicated a positive effect of SGLT-2 inhibitor use on cognitive function score improvement, as demonstrated by the standardized mean difference of 0.88 (95 % CI: 0.32-1.44), particularly among populations with mild cognitive impairment or dementia. This systematic review and meta-analysis indicate a potential role of SGLT-2 inhibitors in reducing the risk of dementia in patients with diabetes mellitus. These findings underscore the need for well-controlled large clinical trials and future research in this field.

Myeloid-Derived Suppressor Cells Mediate Inflammation Resolution in Humans and Mice with Autoimmune Uveoretinitis.

Resolution of inflammation is an active process that leads to tissue homeostasis and involves multiple cellular and molecular mechanisms. Myeloid-derived suppressor cells (MDSCs) have recently emerged as important cellular components in the resolution of inflammation because of their activities to suppress T cell activation. In this article, we show that HLA-DR-CD11b+CD33+CD14+ human MDSCs and CD11b+Ly6G-Ly6C+ mouse MDSCs markedly increased in patients and mice during and before the resolution phase of autoimmune uveoretinitis. CD11b+Ly6C+ monocytes isolated from autoimmune uveoretinitis mice were able to suppress T cell proliferation in culture, and adoptive transfer of the cells accelerated the remission of autoimmune uveoretinitis in mice. Alternatively, depletion of CD11b+Ly6C+ monocytes at the resolution phase, but not CD11b+Ly6G+ granulocytes, exacerbated the disease. These findings collectively indicate that monocytic MDSCs serve as regulatory cells mediating the resolution of autoimmune uveoretinitis.

A role for O-GlcNAcylation in setting circadian clock speed.

Post-translational modifications of one or more central "clock" proteins, most notably time-of-day-dependent changes in phosphorylation, are critical for setting the pace of circadian (≅24 h) clocks. In animals, PERIOD (PER) proteins are the key state variable regulating circadian clock speed and undergo daily changes in abundance and cytoplasmic-nuclear distribution that are partly driven by a complex phosphorylation program. Here, we identify O-GlcNAcylation (O-GlcNAc) as a critical post-translational modification in circadian regulation that also contributes to setting clock speed. Knockdown or overexpression of Drosophila O-GlcNAc transferase (ogt) in clock cells either shortens or lengthens circadian behavioral rhythms, respectively. The Drosophila PERIOD protein (dPER) is a direct target of OGT and undergoes daily changes in O-GlcNAcylation, a modification that is mainly observed during the first half of the night, when dPER is predominantly located in the cytoplasm. Intriguingly, the timing of when dPER translocates from the cytoplasm to the nucleus is advanced or delayed in flies, wherein ogt expression is reduced or increased, respectively. Our results suggest that O-GlcNAcylation of dPER contributes to setting the correct pace of the clock by delaying the timing of dPER nuclear entry. In addition, OGT stabilizes dPER, suggesting that O-GlcNAcylation has multiple roles in circadian timing systems.

Mesenchymal stem/stromal cells precondition lung monocytes/macrophages to produce tolerance against allo- and autoimmunity in the eye.

Intravenously administered mesenchymal stem/stromal cells (MSCs) engraft only transiently in recipients, but confer long-term therapeutic benefits in patients with immune disorders. This suggests that MSCs induce immune tolerance by long-lasting effects on the recipient immune regulatory system. Here, we demonstrate that i.v. infusion of MSCs preconditioned lung monocytes/macrophages toward an immune regulatory phenotype in a TNF-α-stimulated gene/protein (TSG)-6-dependent manner. As a result, mice were protected against subsequent immune challenge in two models of allo- and autoimmune ocular inflammation: corneal allotransplantation and experimental autoimmune uveitis (EAU). The monocytes/macrophages primed by MSCs expressed high levels of MHC class II, B220, CD11b, and IL-10, and exhibited T-cell-suppressive activities independently of FoxP3(+) regulatory T cells. Adoptive transfer of MSC-induced B220(+)CD11b(+) monocytes/macrophages prevented corneal allograft rejection and EAU. Deletion of monocytes/macrophages abrogated the MSC-induced tolerance. However, MSCs with TSG-6 knockdown did not induce MHC II(+)B220(+)CD11b(+) cells, and failed to attenuate EAU. Therefore, the results demonstrate a mechanism of the MSC-mediated immune modulation through induction of innate immune tolerance that involves monocytes/macrophages.

Glucocorticoids induce corneal allograft tolerance through expansion of monocytic myeloid-derived suppressor cells.

Glucocorticoids (GCs) are the most widely used drugs to prevent transplant rejection; however, it is not yet clear how GCs induce immune tolerance in transplantation. Here, we demonstrate that GCs induce tolerance to corneal allografts in mice through expansion of MHC class II- CD11b+ Ly6C+ monocytes in the bone marrow and mobilization of the cells to spleen, draining lymph nodes, and graft site. The GC-induced CD11b+ Ly6C+ monocytes inhibited T cell proliferation in vitro, and adoptive transfer of the cells improved the survival of corneal allografts. Depletion of CD11b+ Ly6C+ cells in mice during GC treatment abrogated the effects of GCs in prevention of immune rejection. Together, the results identify monocytic myeloid-derived suppressor cells as crucial mediators of the GC-induced tolerance in transplantation.

Ly6Chi monocytes are required for mesenchymal stem/stromal cell-induced immune tolerance in mice with experimental autoimmune uveitis.

The cells of the innate immune system, in addition to their capacity to elicit immunity, play a substantial role in immune tolerance induction. Our group has recently shown that a distinct subset of MHC IIhiB220hiCD11bmid suppressive macrophages is increased in the lung by intravenous (IV) administration of mesenchymal stem/stromal cells (MSC) and induces immune tolerance. Herein, we demonstrate that circulating CD11bhiLy6Chi monocytes are precursors to MHC IIhiB220hiCD11bmid macrophages in the lung and required for MSC-induced tolerance in a mouse model of experimental autoimmune uveitis (EAU). Analysis revealed that IV MSC induced an increase in IL-10-expressing MHC IIhiB220hiCD11bmid macrophages in the lung with a concomitant decrease in CD11bhiLy6Chi monocytes. Selective depletion of circulating CD11bhiLy6Chi cells abrogated the effects of MSC in the induction of IL-10hiMHC IIhiB220hiCD11bmid macrophages and immune tolerance in EAU mice. Similarly, an increase in CD4+CD25+Foxp3+ Tregs by MSCs was also reversed by CD11bhiLy6Chi cell depletion. These results suggest that CD11bhiLy6Chi monocytes are critical for MSC-induced immune tolerance.

Mesenchymal stem/stromal cells protect against autoimmunity via CCL2-dependent recruitment of myeloid-derived suppressor cells.

Exogenously administered mesenchymal stem/stromal cells (MSCs) suppress autoimmunity despite transient engraftment. However, the mechanism is unclear. In this study, we report a novel mechanism by which MSCs modulate the immune system by recruiting myeloid-derived suppressor cells in a mouse model of experimental autoimmune uveitis (EAU). Intravenous infusion of MSCs blocked EAU development and reduced Th1 and Th17 responses. Time course analysis revealed an increase of MHC class II(lo)Ly6G(-)Ly6C(hi)CD11b(+) cells in draining lymph nodes by MSCs. These Ly6C(hi)CD11b(+) cells suppressed CD4(+) cell proliferation and Th1/Th17 differentiation and induced CD4(+) cell apoptosis. Adoptive transfer of Ly6C(hi)CD11b(+) cells ameliorated EAU, whereas depletion of Ly6C(hi)CD11b(+) cells abrogated the effects of MSCs. 1.8% of MSCs were present in draining lymph nodes 1 d after infusion, and MSCs with CCL2 knockdown did not increase MHC class II(lo)Ly6G(-)Ly6C(hi)CD11b(+) cells and failed to attenuate EAU. Therefore, our findings demonstrate that MSCs suppress autoimmunity by recruiting myeloid-derived suppressor cells into sites of inflammation in a CCL2-dependent manner.

Phosphorylation of a central clock transcription factor is required for thermal but not photic entrainment.

Transcriptional/translational feedback loops drive daily cycles of expression in clock genes and clock-controlled genes, which ultimately underlie many of the overt circadian rhythms manifested by organisms. Moreover, phosphorylation of clock proteins plays crucial roles in the temporal regulation of clock protein activity, stability and subcellular localization. dCLOCK (dCLK), the master transcription factor driving cyclical gene expression and the rate-limiting component in the Drosophila circadian clock, undergoes daily changes in phosphorylation. However, the physiological role of dCLK phosphorylation is not clear. Using a Drosophila tissue culture system, we identified multiple phosphorylation sites on dCLK. Expression of a mutated version of dCLK where all the mapped phospho-sites were switched to alanine (dCLK-15A) rescues the arrythmicity of Clk(out) flies, yet with an approximately 1.5 hr shorter period. The dCLK-15A protein attains substantially higher levels in flies compared to the control situation, and also appears to have enhanced transcriptional activity, consistent with the observed higher peak values and amplitudes in the mRNA rhythms of several core clock genes. Surprisingly, the clock-controlled daily activity rhythm in dCLK-15A expressing flies does not synchronize properly to daily temperature cycles, although there is no defect in aligning to light/dark cycles. Our findings suggest a novel role for clock protein phosphorylation in governing the relative strengths of entraining modalities by adjusting the dynamics of circadian gene expression.

Biophysico-functional compatibility of Seoul National University (SNU) miniature pig cornea as xenocorneal graft for the use of human clinical trial.

BACKGROUND: Xenocorneal transplantation is one of the solutions for shortage of donor cornea, and remarkable advances have been made in pig-to-rhesus studies from the immunological perspective. Most successful preclinical trials have been carried out with corneas of the Seoul National University (SNU) miniature pig (SNU pig, genetically unmodified) as donor tissues; however, there has been no biophysico-functional evaluation of the SNU pig cornea as a substitute for human cornea. The purpose of this study was to investigate the biophysical and functional compatibility of SNU pig cornea for use in human clinical trials. METHODS: Ninety-three eyeballs obtained from 51 SNU pigs were used to evaluate the physical properties and changes in porcine corneal endothelial cells (PCECs) depending on preservation time and storage condition before surgery, proliferative and functional characteristics of PCECs, and the microbiologic safety of porcine cornea. Corneal diameters and curvatures, axial length, anterior chamber depth, and central corneal thickness were measured and compared with previously reported human data. Corneal endothelial cell density (ECD) was serially measured with a confocal microscope during 7 days of preservation in the same storage solution used for human corneas. Corneal endothelial cell proliferation and immunofluorescence staining of Na- and K-dependent ATPase in PCECs were evaluated after 7 days of preservation. The corneoscleral rims of SNU pigs were cultured for gram-positive bacteria, gram-negative bacteria, and fungi to evaluate their microbiological safety. RESULTS: Corneal diameter and thickness in SNU pigs was larger than human and corneal curvature was flatter; however, they were within surgically operable ranges. Mean ECD (day 0) and ECD loss after 7 days of preservation were 2625 ± 81 cells/mm(2) and 7.60 ± 1.53%, respectively, which is comparable to human ECD and ECD loss in the same conditions. The ECD of SNU pigs was inversely decreased with aging (R(2) = 0.4034, P = 0.001), and the estimated ages of pigs whose mean ECD would be more than 2500 and 2200 cells/mm(2) or more were 48 and 72 months or less, respectively. Mean doubling time of the endothelial cells was 52 to 96 h depending on the method used. The Na- and K-dependent ATPase pump in SNU pig cornea was well maintained for 7 days. No cultured microorganisms were found upon using the modified European Eye Bank Association protocol, which included additional antiseptic management during the enucleation procedure. CONCLUSIONS: In conclusion, SNU pig cornea is feasible for xenocorneal transplantation using the same preservation protocol as human with respect to biophysical and functional properties and can be stored for up to 7 days for transplantation in human clinical trials. An age limitation of donor pigs may be required for qualified corneal products to be used in human trials.

CD39-mediated effect of human bone marrow-derived mesenchymal stem cells on the human Th17 cell function.

This study investigated the immune-modulatory effects of human bone marrow-derived mesenchymal stem cells (hBMSCs) on human Th17 cell function through the CD39-mediated adenosine-producing pathway. The suppressive effects of hBMSCs were evaluated by assessing their effects on the proliferation of Th17 cells and the secretion of interferon (IFN)-γ and interleukin (IL)-17A by Th17 cells with or without anti-CD39 treatment. Changes in CD39 and CD73 expression on the T cells with or without co-culture of hBMSCs were evaluated by flow cytometry. hBMSCs effectively suppressed the proliferation of Th17 cells and the secretion of both IL-17A and IFN-γ from Th17 cells using by both flow cytometry and ELISA, while anti-CD39 treatment significantly reduced the inhibitory effects of hBMSCs on the proliferation and secretion of the Th17 cells. The hBMSCs induced increased expression of the CD39 and CD73 on T cells correlated with the suppressive function of hBMSCs, which was accompanied by increased adenosine production. Our data suggests that hBMSCs can effectively suppress immune responses of the Th17 cells via the CD39-CD73-mediated adenosine-producing pathway.

Agrobacterium tumefaciens-mediated genetic transformation of haptophytes (Isochrysis species).

Isochrysis galbana and Isochrysis sp. are economically important microalgae from the division of haptophytes. Here, we report Agrobacterium-mediated stable DNA transfer into their nuclear genomes. Initial studies were performed to standardize co-cultivation media and determine the sensitivity of the microalgae to selective agents. Up to 1 mg/ml of the antibiotic hygromycin did not inhibit growth, whereas both the haptophytes bleached in artificial seawater (ASW) medium containing micromolar concentrations of the herbicide norflurazon. Co-cultivation of Isochrysis sp. and I. galbana with Agrobacterium tumefaciens strain LBA 4404 harboring the binary vector pCAMBIA 1380-pds-L504R yielded norflurazon-resistant (NR) colonies visible on selective plates after 20-30 days. pCAMBIA 1380-pds-L540R was constructed by cloning a mutated genomic phytoene desaturase (pds) gene from Haematococcus pluvialis as a selectable marker gene into the binary vector system pCAMBIA 1380. Co-cultivation of Isochrysis sp. with A. tumefaciens in ASW medium containing 200 µM of acetosyringone for 72 h produced the highest number of NR cells. For I. galbana, 100 µM of acetosyringone, ASW medium, and 48 h co-cultivation period appeared to be optimum co-cultivation parameters. The NR colonies kept their resistance phenotype for at least 24 months, even in the absence of selective pressure. The transfer of the pds gene in NR cells was shown by PCR amplification of the T-DNA sequences from the genomic DNA of NR cells and Southern blot analysis using T-DNA sequences as probes. The genetic manipulation described here will allow metabolic engineering and a better understanding of several biochemical pathways in the future.

Intraperitoneal infusion of mesenchymal stem/stromal cells prevents experimental autoimmune uveitis in mice.

Autoimmune uveitis is one of the leading causes of blindness. We here investigated whether intraperitoneal administration of human mesenchymal stem/stromal cells (hMSCs) might prevent development of experimental autoimmune uveitis (EAU) in mice. Time course study showed that the number of IFN-γ- or IL-17-expressing CD4(+) T cells was increased in draining lymph nodes (DLNs) on the postimmunization day 7 and decreased thereafter. The retinal structure was severely disrupted on day 21. An intraperitoneal injection of hMSCs at the time of immunization protected the retina from damage and suppressed the levels of proinflammatory cytokines in the eye. Analysis of DLNs on day 7 showed that hMSCs decreased the number of Th1 and Th17 cells. The hMSCs did not reduce the levels of IL-1ß, IL-6, IL-12, and IL-23 which are the cytokines that drive Th1/Th17 differentiation. Also, hMSCs did not induce CD4(+)CD25(+)Foxp3(+) cells. However, hMSCs increased the level of an immunoregulatory cytokine IL-10 and the population of IL-10-expressing B220(+)CD19(+) cells. Together, data demonstrate that hMSCs attenuate EAU by suppressing Th1/Th17 cells and induce IL-10-expressing B220(+)CD19(+) cells. Our results support suggestions that hMSCs may offer a therapy for autoimmune diseases mediated by Th1/Th17 responses.

Two distinct modes of PERIOD recruitment onto dCLOCK reveal a novel role for TIMELESS in circadian transcription.

Negative transcriptional feedback loops are a core feature of eukaryotic circadian clocks and are based on rhythmic interactions between clock-specific repressors and transcription factors. In Drosophila, the repression of dCLOCK (dCLK)-CYCLE (CYC) transcriptional activity by dPERIOD (dPER) is critical for driving circadian gene expression. Although growing lines of evidence indicate that circadian repressors such as dPER function, at least partly, as molecular bridges that facilitate timely interactions between other regulatory factors and core clock transcription factors, how dPER interacts with dCLK-CYC to promote repression is not known. Here, we identified a small conserved region on dPER required for binding to dCLK, termed CBD (for dCLK binding domain). In the absence of the CBD, dPER is unable to stably associate with dCLK and inhibit the transcriptional activity of dCLK-CYC in a simplified cell culture system. CBD is situated in close proximity to a region that interacts with other regulatory factors such as the DOUBLETIME kinase, suggesting that complex architectural constraints need to be met to assemble repressor complexes. Surprisingly, when dPER missing the CBD (dPER(ΔCBD)) was evaluated in flies the clock mechanism was operational, albeit with longer periods. Intriguingly, the interaction between dPER(ΔCBD) and dCLK is TIM-dependent and modulated by light, revealing a novel and unanticipated in vivo role for TIM in circadian transcription. Finally, dPER(ΔCBD) does not provoke the daily hyperphosphorylation of dCLK, indicating that direct interactions between dPER and dCLK are necessary for the dCLK phosphorylation program but are not required for other aspects of dCLK regulation.

Effect of Toll-like receptor 2 and 4 of corneal fibroblasts on cytokine expression with co-cultured antigen presenting cells.

Keratocytes are the first component to contact ocular pathogens when the epithelial barrier breaks down and the emerging evidences indicated keratocytes appeared to be one of the corneal cellular immune components. Little is known about the role of Toll-like receptors (TLRs) in keratocytes, although it has been well documented that keratocytes constitutively express various TLRs including TLR2 and TLR4. In this in vitro study, the authors focused on the role of keratocytes in corneal innate immune system and cross-talk of keratocytes with resident antigen presenting cells (APCs), especially through TLR2 and TLR4. Primary cultivated keratocytes (corneal fibroblasts) from C57BL/6 mice per se actively secreted pro-inflammatory cytokines, especially interleukin (IL)-6, with a dose-dependent manner in response to Pam3CSK4 or lipopolysaccharide (LPS) challenge. With co-culture of corneal fibroblasts with APCs per se, secretion of IL-6 and tumor necrosis factor (TNF)-α was markedly increased and it was counterbalanced by concurrent increase in IL-10 and tumor growth factor-ß1. After Pam3CSK4 or LPS stimulation, this cytokine balance was completely broken down by overwhelming amplification of IL-6 and TNF-α secretion, especially in co-culture of corneal fibroblasts with macrophages, rather than with dendritic cells. Using corneal fibroblasts from TLR2 or TLR4 knockout mice, we could find the reversal of Pam3CSK4 or LPS-responsive dose-dependent increment in IL-6 and TNF-α. These results implied that corneal fibroblasts and their TLRs could be key components for the ocular homeostasis and pathogen-associated ocular innate immunity.

Actimicrobium antarcticum gen. nov., sp. nov., of the family Oxalobacteraceae, isolated from Antarctic coastal seawater.

A Gram-negative, non-motile, catalase- and oxidase- positive, strictly aerobic, and short rod-shaped bacterium that was designated strain KOPRI 25157(T) was isolated from coastal seawater sample in Antarctica. The temperature and pH ranges for growth on R2A agar were 10-20°C, and 5.0-10.0, respectively. Phylogenetic analyses of the 16S rRNA gene sequence of strain KOPRI 25157(T) showed it to belong to the family Oxalobacteraceae of the class Betaproteobacteria, and it formed a distinct clade from other recognized members of the family. DNA G + C content was 65.9 mol%. Major ubiquinone was Q-8. Predominant cellular fatty acids were C(16:1) ω7c/15 iso 2OH (56.4%) and C(16:1) (30.5%). Major polar lipids were phosphatidylglycerol, phosphatidylethanolamine, and unknown lipid. On the basis of these data, it is proposed that strain KOPRI 25157(T) is the representative of a novel genus, for which the name Actimicrobium gen. nov. is proposed in the family Oxalobacteraceae. The type strain for Actimicrobium antarcticum sp. nov. is KOPRI 25157(T) (=JCM 16673(T)=KCTC 23040(T)).

Coculture with BJ fibroblast cells inhibits the adipogenesis and lipogenesis in 3T3-L1 cells.

Mouse or human fibroblasts are commonly used as feeder cells to prevent differentiation in stem or primary cell culture. In the present study, we addressed whether fibroblasts can affect the differentiation of adipocytes. We found that the differentiation of 3T3-L1 preadipocytes was strongly suppressed when the cells were cocultured with human fibroblast (BJ) cells. BrdU incorporation analysis indicated that mitotic clonal expansion, an early event required for 3T3-L1 cell adipogenesis, was not affected by BJ cells. The 3T3-L1 cell expression levels of peroxisome proliferator-activated receptor gamma2, CCAAT/enhancer-binding protein alpha (C/EBPalpha), sterol regulatory element binding protein-1c, and Krüppel-like factor 15, but not those of C/EBPbeta or C/EBPdelta, were decreased by coculture with BJ cells. When mature 3T3-L1 adipocytes were cocultured with BJ cells, their lipid contents were significantly reduced, with decreased fatty acid synthase expression and increased phosphorylated form of acetyl-CoA carboxylase 1. Our data indicate that coculture with BJ fibroblast cells inhibits the adipogenesis of 3T3-L1 preadipocytes and decreases the lipogenesis of mature 3T3-L1 adipocytes.

Analysis of complete genome sequences of swine hepatitis E virus and possible risk factors for transmission of HEV to humans in Korea.

The hepatitis E virus (HEV) is an emerging zoonotic agent, for which pigs are the most important reservoir. Complete genome sequences of two swine HEV strains, designated swKOR-1 and swKOR-2, were determined via RT-PCR and RACE-PCR. The strains contained genomes composed of 7,222- and 7,221-bp excluding the poly(A) tails, respectively. The swKOR-1 and swKOR-2 strains were classified into subtype 3a of genotype 3 via phylogenetic analysis. These strains formed a distinctive cluster in the phylogenetic tree with human and swine HEVs isolated in the USA and human HEVs isolated in Japan. Anti-HEV antibodies were identified via ELISA in 8 of 99 (8.1%) cats, whereas, among 115 cattle and 213 dogs, no HEV-specific antibodies were detected. The conserved RNA-dependent RNA polymerase (RdRp) gene of HEV could be detected via RT-PCR in 8.7% of raw oysters collected from coastal regions in Korea. The HEV RNAs detected in oysters were identified as belonging to subtype 3a. The HEV RNAs in oysters most closely resembled that of the swKOR-2 strain. They also showed a close genetic relationship with the swKOR-1 strain and the swine and human HEVs isolated in the USA. This is the first report describing the detection in oysters of HEV that may have originated from genotype 3 swine HEV in Korea. Pigs and cats infected with HEV, as well as oysters contaminated with HEV, are potential risk factors for HEV transmission to humans.

Mesenchymal Stem and Stromal Cells Harness Macrophage-Derived Amphiregulin to Maintain Tissue Homeostasis.

The cross-talk between mesenchymal stem and stromal cells (MSCs) and macrophages is critical for the restoration of tissue homeostasis after injury. Here, we demonstrate a pathway through which MSCs instruct macrophages to resolve inflammation and preserve tissue-specific stem cells, leading to homeostasis in mice with autoimmune uveoretinitis and sterile-injury-induced corneal epithelial stem cell deficiency. Distinct from their conventional role in macrophage reprogramming to anti-inflammatory phenotype by a PGE2-dependent mechanism, MSCs enhance the phagocytic activity of macrophages, which partly depends on the uptake of MSC mitochondria-containing extracellular vesicles. The MSC-primed macrophages increase the secretion of amphiregulin (AREG) in a phagocytosis-dependent manner. AREG is essential for MSC-primed macrophages to suppress immune responses through regulatory T (Treg) cells and to protect corneal epithelial stem cells via apoptosis inhibition and proliferation promotion. Hence, the data reveal that MSCs harness macrophage-derived AREG to maintain tissue homeostasis after injury and provide a therapeutic target in immune-mediated disease and regenerative medicine.

Mesenchymal stromal cells induce distinct myeloid-derived suppressor cells in inflammation.

Mesenchymal stem/stromal cells (MSCs) regulate immunity through myeloid-derived suppressor cells (MDSCs), which are a heterogeneous population of immature myeloid cells with phenotypic and functional diversity. Herein, we identified a distinct subset of MDSCs induced by MSCs in the BM under inflammatory conditions. MSCs directed the differentiation of Ly6Glo BM cells from CD11bhiLy6Chi cells to CD11bmidLy6Cmid cells both in cell contact-independent and -dependent manners upon GM-CSF stimulation in vitro and in mice with experimental autoimmune uveoretinitis (EAU). RNA-Seq indicated that MSC-induced CD11bmidLy6CmidLy6Glo cells had a distinct transcriptome profile from CD11bhiLy6ChiLy6Glo cells. Phenotypic, molecular, and functional analyses showed that CD11bmidLy6CmidLy6Glo cells differed from CD11bhiLy6ChiLy6Glo cells by low expression of MHC class II and costimulatory molecules and proinflammatory cytokines, high production of immunoregulatory molecules, lack of change in response to LPS, and inhibition of T cell proliferation and activation. Consequently, adoptive transfer of MSC-induced CD11bmidLy6CmidLy6Glo cells significantly attenuated the development of EAU in mice. Further mechanistic study revealed that suppression of prostaglandin E2 (PGE2) and HGF secretion in MSCs by siRNA transfection partially reversed the effects of MSCs on MDSC differentiation. Altogether, data demonstrate that MSCs drive the differentiation of BM cells toward CD11bmidLy6CmidLy6Glo MDSCs, in part through HGF and COX-2/PGE2, leading to resolution of ocular autoimmune inflammation.

Bilateral Effect of the Unilateral Corneal Nerve Cut on Both Ocular Surface and Lacrimal Gland.

Purpose: This study investigated the effect of a unilateral cut of the corneal nerve on the bilateral ocular surface and tear secretory function. Methods: Seven-week-old female BALB/c mice were divided into control and nerve-cutting (NC) groups (n = 60). The left cornea was partially incised with a 2-mm circular trephine through the upper half of the stromal layer. Lissamine green corneal staining and tear volume measurements were conducted, and corneal whole-mount staining using class III ß-tubulin antibody was performed to assess corneal nerves. Flow cytometric analyses for dendritic cells (DCs), CD4+/CD8+ and regulatory T cells and ELISA for neuropeptides were performed. Results: The grading of corneal staining increased in the NC group, while the tear volume decreased over the 4 weeks. The nerve density decreased in bilateral corneas over 2 weeks. At day 14, CD11b+ or CD11c+ DCs and the mature DCs expressing CD86 or MHCII increased in bilateral cornea/conjunctiva. At day 28, CD11c+CD86hi, CD11c+MHCIIhi, Th17 and IFN-γ-secreting CD8+ T cells highly increased in bilateral draining lymph nodes. CD4+CD25hiFoxp3hi and CD8+CD25hiFoxp3hi regulatory T cells notably increased in the spleen. In ELISA, neuropeptide Y, calcitonin gene-related peptide, and vasoactive intestinal peptide were generally suppressed in the extraorbital lacrimal glands at day14. Conclusions: The unilateral corneal nerve severing resulted in activation of the immune cells on the ocular surface and dysregulated lacrimal secretion bilaterally through the bidirectional neuronal signals. It suggests that the unilateral corneal nerve damage may alter immune homeostasis and mechanistically participate in the development of bilateral inflammatory disorders such as dry eye.