Acute ocular chemical burns are ophthalmic emergencies requiring immediate diagnosis and treatment as they may lead to permanent impairment of vision. The clinical manifestations of such burns are produced by exacerbated innate immune response via the infiltration of inflammatory cells and activation of stromal fibroblasts. New therapies are emerging that are dedicated to repair mechanisms that improve the ocular surface after damage; for example, transplantation of stem cells (SC) has been successfully reported for this purpose. The pursuit of easily accessible, noninvasive procedures to obtain SC has led researchers to focus on human tissues such as amniotic membrane. Human amniotic mesenchymal SC (hAM-MSC) inhibits proinflammatory and fibrotic processes in different diseases. hAM-MSC expresses low levels of classical MHC-I and they do not express MHC-II, making them suitable for regenerative medicine. The aim of this study was to evaluate the effect of intracameral injection of hAM-MSC on the clinical manifestations, the infiltration of inflammatory cells, and the activation of stromal fibroblasts in a corneal alkali-burn model. We also determined the in vitro effect of hAM-MSC conditioned medium (CM) on α-SMA+ human limbal myofibroblast (HLM) frequency and on release of neutrophil extracellular traps (NETs). Our results show that intracameral hAM-MSC injection reduces neovascularization, opacity, stromal inflammatory cell infiltrate, and stromal α-SMA+ cells in our model. Moreover, in in vitro assays, CM from hAM-MSC decreased the quantity of α-SMA+ HLM and the release of NETs. These results suggest that intracameral hAM-MSC injection induces an anti-inflammatory and anti-fibrotic environment that promotes corneal wound healing.

The mesenchymal stem cells obtained from human amniotic membrane (hAMSC) possess immunosuppressive functions through soluble factors such as prostanoids and proteins; thus, they have been proposed to ameliorate inflammatory processes. On the other hand, activated neutrophils are cells of the first line of immune defense that are able to release extracellular traps (NETs). NETs are formed of DNA and granular components; however, the excessive release of NETs is associated with the development of autoimmune and chronic inflammatory diseases. In this study, we identified that conditioned medium (CM) from hAMSC was able to diminish NETs release, as well as the production of reactive oxygen species (ROS) and the mitochondrial membrane potential from LPS-stimulated mouse bone marrow-derived neutrophils (BMN). Interestingly, NETs inhibition, ROS levels decrease and mitochondrial membrane potential loss were reverted when LPS-stimulated murine derived BMN were exposed to the CM from hAMSC transfected with TSG-6-siRNA. Finally, rhTSG6 was able to significantly diminish NETs release in BMN. These data suggest an inhibition mechanism of NETs ROS-dependent in which TSG-6 participates. Consequently, we propose the hAMSC use as a therapeutic candidate in the treatment of inflammatory diseases in which NETs are involved.

Amniotic membrane (AM) is the inner layer of the placenta, which is in contact with the fetus; it has been used for transplantation in ocular surface diseases. It has been reported that amniotic membrane promotes epithelialization, inhibits angiogenesis and diminishes ocular inflammation. A persistent epithelial defect is the delay in epithelial wound healing caused by infiltrating inflammatory cells into the cornea and amniotic membrane transplantation has been successfully used in its treatment, however the mechanism of action in inhibiting inflammation it is not well understood. This study was aimed at determining whether denuded amniotic membrane (dAM) induces anti-inflammatory effects on peripheral blood mononuclear cells. Methods: Human peripheral blood mononuclear cells (PBMC) were cultured on dAM. Proliferation and apoptosis assays were performed on PBMC; and synthesis and secretion of pro-inflammatory cytokines by these cells was analyzed. Results: dAM induced apoptosis and inhibited cell proliferation of PBMC; and abolished the synthesis and the secretion of pro-inflammatory cytokines even when they were LPS stimulated. In contrast, when PBMC were cultured on hydrophilic membrane cell culture inserts, apoptosis was not significantly induced, cell proliferation was conserved, and synthesis and secretion of pro-inflammatory cytokines were not affected. Conclusions: Taken together, these results could explain the anti-inflammatory in vivo effects observed when the amniotic membrane is used as a transplant.

Type 2 diabetes mellitus (T2DM), characterized by hyperglycemia and dyslipidemia, leads to nonproliferative diabetic retinopathy (NPDR). NPDR is associated with blood-retina barrier disruption, plasma exudates, microvascular degeneration, elevated inflammatory cytokine levels, and monocyte (Mo) infiltration. Whether and how the diabetes-associated changes in plasma lipid and carbohydrate levels modify Mo differentiation remains unknown. Here, we show that mononuclear phagocytes (MPs) in areas of vascular leakage in DR donor retinas expressed perilipin 2 (PLIN2), a marker of intracellular lipid load. Strong upregulation of PLIN2 was also observed when healthy donor Mos were treated with plasma from patients with T2DM or with palmitate concentrations typical of those found in T2DM plasma, but not under high-glucose conditions. PLIN2 expression correlated with the expression of other key genes involved in lipid metabolism (ACADVL, PDK4) and the DR biomarkers ANGPTL4 and CXCL8. Mechanistically, we show that lipid-exposed MPs induced capillary degeneration in ex vivo explants that was inhibited by pharmaceutical inhibition of PPARγ signaling. Our study reveals a mechanism linking dyslipidemia-induced MP polarization to the increased inflammatory cytokine levels and microvascular degeneration that characterize NPDR. This study provides comprehensive insights into the glycemia-independent activation of Mos in T2DM and identifies MP PPARγ as a target for inhibition of lipid-activated MPs in DR.

Nuclear factor of activated T cells 5 (NFAT5) is a transcription factor within the Rel family, primarily recognized for its role in cellular adaptation to osmotic stress, particularly in hypertonic and hyperosmotic environments. Beyond osmotic regulation, NFAT5 responds to diverse stimuli, including cytokines, growth factors, oxidative stress, and microbial signals. This versatility enables NFAT5 to regulate essential cellular processes such as proliferation, survival, migration, and vascular remodelling. In the immune system, NFAT5 modulates the function of monocytes, macrophages, astrocytes, microglia, and T cells, contributing to immune homeostasis and inflammatory responses. Dysregulation of NFAT5 activity is implicated in various pathological conditions, including autoimmune diseases, cancer, and cardiovascular disorders, largely due to its ability to control genes involved in inflammatory and immune pathways under both isotonic and hypertonic conditions. Recent studies have unveiled new regulatory mechanisms, including interactions with non-coding RNAs, offering deeper insights into the functional landscape of NFAT5 and its therapeutic potential. This review delves into the multifaceted roles of NFAT5 in health and disease, emphasizing its emerging importance as a promising therapeutic target.