Innate Immune System Activation, Inflammation and Corneal Wound Healing

Diesel exhaust exposure induced squamous metaplasia of corneal epithelium via yes-associated protein activation

Atmospheric pollution has been demonstrated to be associated with ocular surface diseases characterized by corneal epithelial damage, including impaired barrier function and squamous metaplasia. However, the specific mechanisms underlying the impact of atmospheric pollution on corneal damage are still unknow. To address this gap in knowledge, we conducted a study using a whole-body exposure system to investigate the detrimental effects of traffic-related air pollution, specifically diesel exhaust (DE), on corneal epithelium in C57BL/6 mice over a 28-day period. Following DE exposure, the pathological alterations in corneal epithelium, including significant increase in corneal thickness and epithelial stratification, were observed in mice. Additionally, exposure to DE was also shown to disrupt the barrier functions of corneal epithelium, leading to excessive proliferation of basal cells and even causing squamous metaplasia in corneal epithelium. Further studies have found that the activation of yes-associated protein (YAP), characterized by nuclear translocation, may play a significant role in DE-induced corneal squamous metaplasia. In vitro assays confirmed that DE exposure triggered the YAP/β-catenin pathway, resulting in squamous metaplasia and destruction of barrier functions. These findings provide the preliminary evidence that YAP activation is one of the mechanisms of the damage to corneal epithelium caused by traffic-related air pollution. These findings contribute to the knowledge base for promoting eye health in the context of atmospheric pollution.

Infectious Keratitis in Patients Over 65: A Review on Treatment and Preserving Eyesight

Infectious keratitis (IK) represents a significant global health concern, ranking as the fifth leading cause of blindness worldwide despite being largely preventable and treatable. Elderly populations are particularly susceptible due to age-related changes in immune response and corneal structure. However, research on IK in this demographic remains scarce. Age-related alterations such as increased permeability and reduced endothelial cell density further compound susceptibility to infection and hinder healing mechanisms. Additionally, inflammaging, characterized by chronic inflammation that develops with advanced age, disrupts the ocular immune balance, potentially exacerbating IK and other age-related eye diseases. Understanding these mechanisms is paramount for enhancing IK management, especially in elderly patients. This review comprehensively assesses risk factors, clinical characteristics, and management strategies for bacterial, viral, fungal, and acanthamoeba keratitis in the elderly population, offering crucial insights for effective intervention.

Photothermal Iron-Based Riboflavin Microneedles for the Treatment of Bacterial Keratitis via Ion Therapy and Immunomodulation

Bacterial biofilm formation protects bacteria from antibiotics and the immune system, excessive inflammation further complicates treatment. Here, iron-based metal-organic framework (MIL-101)-loaded riboflavin nanoparticles are designed for the therapeutic challenge of biofilm infection and hyperinflammation in bacterial keratitis. Specifically, MIL-101 produces a thermal effect under exogenous near-infrared light irradiation, which synergizes with ferroptosis-like bacterial death induced by iron ions to exert an effective biofilm infection eradication effect. On the other hand, the disintegration of MIL-101 sustains the release of riboflavin, which inhibits the pro-inflammatory response of macrophage over-activation by modulating their phenotypic switch. In addition, to solve the problems of short residence time, poor permeability, and low bioavailability of corneal medication, the MR@MN microneedle patch is further prepared by loading nanoparticles into SilMA hydrogel, which ultimately achieves painless, transepithelial, and highly efficient drug delivery. In vivo and ex vivo experiments demonstrate the effectiveness of this approach in eliminating bacterial infection and promoting corneal healing. Therefore, the MRMN patch, acting as an ocular drug delivery system with the ability of rapid corneal healing, promises a cost-effective solution for the treatment of bacterial keratitis, which may also lead to a new approach for treating bacterial keratitis in clinics.

Ebselen improves fungal keratitis through exerting anti-inflammation, anti-oxidative stress, and antifungal effects

Fungal keratitis is a severely vision-threatening corneal infection, where the prognosis depends on both fungal virulence and host immune defense. Inappropriate host responses can induce substantial inflammatory damage to the cornea. Therefore, in the treatment of fungal keratitis, it is important to concurrently regulate the immune response while efforts are made to eliminate the pathogen. Ebselen is a widely studied organo-selenium compound and has been demonstrated to have antifungal, antibacterial, anti-inflammatory, and oxidative stress-regulatory properties. The effectiveness of ebselen for the treatment of fungal keratitis remains unknown. In this study, ebselen was demonstrated to produce a marked inhibitory effect on Aspergillus fumigatus (A. fumigatus), including spore germination inhibition, mycelial growth reduction, and fungal biofilm disruption. The antifungal activity of ebselen was related to the cell membrane damage caused by thioredoxin (Trx) system inhibition-mediated oxidative stress. On the contrary, ebselen enhanced the antioxidation of Trx system in mammalian cells. Further, ebselen was proven to suppress the expressions of inflammatory mediators (IL-1β, IL-6, TNF-α, COX-2, iNOS, and CCL2) and reduce the production of oxidative stress-associated indicators (ROS, NO, and MDA) in fungi-stimulated RAW264.7 cells. In addition, ebselen regulated PI3K/Akt/Nrf2 and p38 MAPK signaling pathways, which contributed to the improvement of inflammation and oxidative stress. Finally, we verified the therapeutic effect of ebselen on mouse fungal keratitis. Ebselen improved the prognosis and reduced the fungal burden in mouse corneas. Expressions of inflammatory mediators, as well as the infiltration of macrophages and neutrophils in the cornea were also obviously decreased by ebselen. In summary, ebselen exerted therapeutic effects by reducing fungal load and protecting host tissues in fungal keratitis, making it a promising treatment for fungal infections.

Conditional deletion of Zeb1 in Csf1r+ cells reduces inflammatory response of the cornea to alkali burn

ZEB1 is an essential factor in embryonic development. In adults, it is often highly expressed in malignant tumors with low expression in normal tissues. The major biological function of ZEB1 in developing embryos and progressing cancers is to transdifferentiate cells from an epithelial to mesenchymal phenotype; but what roles ZEB1 plays in normal adult tissues are largely unknown. We previously reported that the reduction of Zeb1 in monoallelic global knockout (Zeb1+/-) mice reduced corneal inflammation-associated neovascularization following alkali burn. To uncover the cellular mechanism underlying the Zeb1 regulation of corneal inflammation, we functionally deleted Zeb1 alleles in Csf1r+ myeloid cells using a conditional knockout (cKO) strategy and found that Zeb1 cKO reduced leukocytes in the cornea after alkali burn. The reduction of immune cells was due to their increased apoptotic rate and linked to a Zeb1-downregulated apoptotic pathway. We conclude that Zeb1 facilitates corneal inflammatory response by maintaining Csf1r+ cell viability.

Formononetin protects against Aspergillus fumigatus Keratitis: Targeting inflammation and fungal load

PURPOSE

To investigate the potential treatment of formononetin (FMN) on Aspergillus fumigatus (A. fumigatus) keratitis with anti-inflammatory and antifungal activity.

METHODS

The effects of FMN on mice with A. fumigatus keratitis were evaluated through keratitis clinical scores, hematoxylin-eosin (HE) staining, and plate counts. The expression of pro-inflammatory factors was measured using RT-PCR, ELISA, or Western blot. The distribution of macrophages and neutrophils was explored by immunofluorescence staining. The antifungal properties of FMN were assessed through minimum inhibitory concentration (MIC), propidium iodide (PI) staining, fungal spore adhesion, and biofilm formation assay.

RESULTS

In A. fumigatus keratitis mice, FMN decreased the keratitis clinical scores, macrophages and neutrophils migration, and the expression of TNF-α, IL-6, and IL-1β. In A. fumigatus-stimulated human corneal epithelial cells (HCECs), FMN reduced the expression of IL-6, TNF-α, IL-1β, and NLRP3. FMN also decreased the expression of thymic stromal lymphopoietin (TSLP) and thymic stromal lymphopoietin receptor (TSLPR). Moreover, FMN reduced the levels of reactive oxygen species (ROS) induced by A. fumigatus in HCECs. Furthermore, FMN inhibited A. fumigatus growth, prevented spore adhesion and disrupted fungal biofilm formation in vitro. In vivo, FMN treatment reduced the fungal load in mice cornea at 3 days post infection (p.i.).

CONCLUSION

FMN demonstrated anti-inflammatory and antifungal properties, and exhibited a protective effect on mouse A. fumigatus keratitis.

Recognition of Mycobacterium tuberculosis by macrophage Toll-like receptor and its role in autophagy

BACKGROUND

The pathogen responsible for tuberculosis is called Mycobacterium tuberculosis. Its interaction with macrophages has a significant impact on the onset and progression of the disease.

METHODS

The respiratory pathway allows Mycobacterium tuberculosis to enter the body's lungs where it battles immune cells before being infected latently or actively. In the progress of tuberculosis, Mycobacterium tuberculosis activates the body's immune system and creates inflammatory factors, which cause tissue inflammation to infiltrate and the creation of granulomas, which seriously harms the body. Toll-like receptors of macrophage can mediate host recognition of Mycobacterium tuberculosis, initiate immune responses, and participate in macrophage autophagy. New host-directed therapeutic approaches targeting autophagy for drug-resistant Mycobacterium tuberculosis have emerged, providing new ideas for the effective treatment of tuberculosis.

CONCLUSIONS

In-depth understanding of the mechanisms by which macrophage autophagy interacts with intracellular Mycobacterium tuberculosis, as well as the study of potent and specific autophagy-regulating molecules, will lead to much-needed advances in drug discovery and vaccine design, which will improve the prevention and treatment of human tuberculosis.

Botulinum toxin type A inhibits M1 macrophage polarization by deactivation of JAK2/STAT1 and IκB/NFκB pathway and contributes to scar alleviation in aseptic skin wound healing

The non-neuronal and non-muscular effects of botulinum toxin type A (BTXA) on scar reduction has been discovered. This study was designed to investigate the effects of BTXA on macrophages polarization during the early stage of skin repair. A skin defect model was established on the dorsal skin of SD rats. BTXA was intracutaneous injected into the edge of wound immediately as the model was established. Histological examinations were performed on scar samples. Raw 264.7 was selected as the cell model of recruited circulating macrophages, and was induced for M1 polarization by LPS. Identify the signaling pathways that primarily regulated M1 polarization and respond to BTXA treatment. Application of BTXA at early stage of injury significantly reduced the scar diameter without delaying wound closure. BTXA treatment improved fiber proliferation and arrangement, and inhibited angiogenesis in scar granular tissue. The number of M1 macrophages and the levels of pro-inflammation were decreased after treated with BTXA in scar tissues. LPS activated JAK2/STAT1 and IκB/NFκB pathways were downregulated by BTXA, as well as LPS induced M1 polarization. At early stage of skin wound healing, injection of BTXA effectively reduced the number of M1 macrophages and the levels of pro-inflammatory mediators which contributes to scar alleviation. BTXA resisted the M1 polarization of macrophages induced by LPS via deactivating the JAK2/STAT1 and IκB/NFκB pathways.

Effects of dietary supplementation of glycerol monolaurate on laying performance, egg quality, antioxidant capacity, intestinal morphology and immune function in late-phase laying hens

The objective of this study was to evaluate the effects of different levels of glycerol monolaurate (GML) on laying performance, egg quality, antioxidant capacity, intestinal morphology and immune function in late-phase laying hens. A total of 480 Hy-Line Variety Brown hens (age 54 wk) were randomly assigned to 5 treatments: the control group (basal diet) and 4 GML groups (basal diet supplemented with 100, 200, 300, and 400 mg/kg GML). Each treatment consisted of 8 replicates with 12 hens each and the trial lasted for 8 wk. The results showed that dietary inclusion of GML increased the ADFI in the entire experimental period and the average egg weight in wk 5 to 8 and wk 1 to 8 of the experiment (linear, P < 0.05). Dietary GML addition linearly increased albumen height, Haugh unit and yolk color, and quadratically increased eggshell thickness (P < 0.05). The serum SOD activity, T-AOC and IgG concentrations in the 200 mg/kg GML group, and GSH-Px activity in 200 and 300 mg/kg GML groups were increased, while the MDA concentration in 200 and 300 mg/kg GML groups was decreased than those in the control group (P < 0.05). The jejunal villus height and villus height: crypt depth in 300 mg/kg GML group were higher than that in the control group (P < 0.05). The mRNA expression of TLR4, IL-1β and TNF-α in spleen and jejunum decreased with the increase of dietary GML concentration (linear, P < 0.05). In conclusion, dietary GML supplementation could improve egg quality, antioxidant capacity, intestinal morphology and immune function in late-phase laying hens, and dietary 300 mg/kg GML inclusion is suggested.

Insulin eye drops improve corneal wound healing in STZ-induced diabetic mice by regulating corneal inflammation and neuropeptide release

INTRODUCTION

In recent years, insulin eye drops have attracted increasing attention from researchers and ophthalmologists. The aim of this study was to investigate the efficacy and possible mechanism of action of insulin eye drops in diabetic mice with corneal wounds.

METHODS

A type 1 diabetes model was induced, and a corneal epithelial injury model of 2.5 mm was established. We used corneal fluorescein staining, hematoxylin-eosin (H-E) staining and the Cochet-Bonnet esthesiometer to examine the process of wound healing. Subsequently, the expression levels of Ki-67, IL-1β, β3-tubulin and neuropeptides, including substance P (SP) and calcitonin gene-related peptide (CGRP), were examined at 72 h after corneal injury.

RESULTS

Fluorescein staining demonstrated an acceleration of the recovery of corneal epithelial injury in diabetic mice compared with the saline treatment, which was further evidenced by the overexpression of Ki-67. Moreover, 72 h of insulin application attenuated the expression of inflammatory cytokines and neutrophil infiltration. Remarkably, the results demonstrated that topical insulin treatment enhanced the density of corneal epithelial nerves, as well as neuropeptide SP and CGRP release, in the healing cornea via immunofluorescence staining.

CONCLUSIONS

Our results indicated that insulin eye drops may accelerate corneal wound healing and decrease inflammatory responses in diabetic mice by promoting nerve regeneration and increasing levels of neuropeptides SP and CGRP.

Aquaporins in the Cornea

The cornea is an avascular, transparent tissue that allows light to enter the visual system. Accurate vision requires proper maintenance of the cornea's integrity and structure. Due to its exposure to the external environment, the cornea is prone to injury and must undergo proper wound healing to restore vision. Aquaporins (AQPs) are a family of water channels important for passive water transport and, in some family members, the transport of other small molecules; AQPs are expressed in all layers of the cornea. Although their functions as water channels are well established, the direct function of AQPs in the cornea is still being determined and is the focus of this review. AQPs, primarily AQP1, AQP3, and AQP5, have been found to play an important role in maintaining water homeostasis, the corneal structure in relation to proper hydration, and stress responses, as well as wound healing in all layers of the cornea. Due to their many functions in the cornea, the identification of drug targets that modulate the expression of AQPs in the cornea could be beneficial to promote corneal wound healing and restore proper function of this tissue crucial for vision.

Topical application of calcitonin gene-related peptide as a regenerative, antifibrotic, and immunomodulatory therapy for corneal injury

Calcitonin gene-related peptide (CGRP) is a multifunctional neuropeptide abundantly expressed by corneal nerves. Using a murine model of corneal mechanical injury, we found CGRP levels in the cornea significantly reduced after injury. Topical application of CGRP as an eye drop accelerates corneal epithelial wound closure, reduces corneal opacification, and prevents corneal edema after injury in vivo. CGRP promotes corneal epithelial cell migration, proliferation, and the secretion of laminin. It reduces TGF-β1 signaling and prevents TGF-β1-mediated stromal fibroblast activation and tissue fibrosis. CGRP preserves corneal endothelial cell density, morphology, and pump function, thus reducing corneal edema. Lastly, CGRP reduces neutrophil infiltration, macrophage maturation, and the production of inflammatory cytokines in the cornea. Taken together, our results show that corneal nerve-derived CGRP plays a cytoprotective, pro-regenerative, anti-fibrotic, and anti-inflammatory role in corneal wound healing. In addition, our results highlight the critical role of sensory nerves in ocular surface homeostasis and injury repair.

In Vitro Effect of Propofol on the Expression of Genes Involved in Inflammation and Apoptosis in Corneal Activated Keratocytes

PURPOSE

We investigated the effect of propofol (0.5, 5, and 50 μM) on the gene expression of inflammatory cytokines [ IL-1β , IL-6 , transforming growth factor β ( TGF-β ), and LIF ] and apoptosis process ( BCL-2 and Bax ) in corneal activated keratocytes (CAKs).

METHODS

CAKs (10 6 cells/10 cm 2 ) were exposed to propofol at a concentration of 0.5, 5, and 50 μM for 24 hours at 37°C. The control group did not receive propofol at the same time or under the same condition. Ribonucleic acid (RNA) extraction, complementary DNA (cDNA) synthesis, and real-time polymerase chain reaction (PCR) were performed to quantify the relative expression of IL-1β , IL-6 , TGF-β , LIF , BCL-2 , and Bax expression in the treated versus control cells.

RESULT

The results of this study showed that propofol treatment (0.5 and 5 μM) led to the downregulation of IL-1β and IL-6 gene expression in CAKs. TGF-β (with a role in fibrogenesis) was not changed in 0.5 and 5 μM propofol-treated CAKs, whereas CAKs treated with 50 μM propofol showed upregulation of the TGF-β gene. LIF (with a role in regeneration) was upregulated in 0.5 and 5 μM propofol-treated CAKs. The BCL-2/Bax ratio (as the antiapoptosis index) was increased in CAKs treated with 0.5 μM propofol and indicated the induction of an antiapoptotic effect.

CONCLUSIONS

We showed that CAKs treatment with propofol, at concentrations of 0.5 and 5 μM, could decrease the expression of genes related to inflammation and enhance the genes associated with cell regeneration. While 50 μM propofol treatment might induce CAK fibrogenesis. This proof-of-concept study could preserve a groundwork for future drug design for the treatment of corneal stromal diseases and ocular regenerative medicine.

The Role of Macrophage Migration Inhibitory Factor (MIF) and D-Dopachrome Tautomerase (D-DT/MIF-2) in Infections: A Clinical Perspective

Macrophage migration inhibitory factor (MIF) and its homolog, D-dopachrome tautomerase (D-DT), are cytokines that play critical roles in the immune response to various infectious diseases. This review provides an overview of the complex involvement of MIF and D-DT in bacterial, viral, fungal, and parasitic infections. The role of MIF in different types of infections is controversial, as it has either a protective function or a host damage-enhancing function depending on the pathogen. Depending on the specific role of MIF, different therapeutic options for MIF-targeting drugs arise. Human MIF-neutralizing antibodies, anti-parasite MIF antibodies, small molecule MIF inhibitors or MIF-blocking peptides, as well as the administration of exogenous MIF or MIF activity-augmenting small molecules have potential therapeutic applications and need to be further explored in the future. In addition, MIF has been shown to be a potential biomarker and therapeutic target in sepsis. Further research is needed to unravel the complexity of MIF and D-DT in infectious diseases and to develop personalized therapeutic approaches targeting these cytokines. Overall, a comprehensive understanding of the role of MIF and D-DT in infections could lead to new strategies for the diagnosis, treatment, and management of infectious diseases.

Host cell-type and pathogen-specific immunomodulatory functions of macrophage migration inhibitory factor (MIF) in infectious keratitis

Therapeutic management of inflammation in infectious keratitis (IK) requires new strategy and targets for selective immunomodulation. Targeting host cell-type specific inflammatory responses might be a viable strategy to curtail unnecessary inflammation and reduce tissue damage without affecting pathogen clearance. This study explores the possibility of pathogen and host cell-type dependent differences in the inflammatory pathways relevant in the pathogenesis of IK. Human corneal epithelial cell line (HCEC) and phorbol 12-myristate-13 acetate (PMA) differentiated THP-1 macrophage line were infected with either Aspergillus flavus conidia or Acanthamoeba castellanii trophozoites and the elicited inflammatory responses were studied in terms of gene expression and secretion of proinflammatory factors interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-α) and an upstream inflammatory regulator and mediator protein-the Macrophage Migration Inhibitory Factor (MIF). Given the pleotropic mode of MIF function in diverse cell types relevant in many human diseases, we tested if MIF driven responses to infection is different in HCECs and THP-1 macrophages by studying its expression, secretion and involvement in inflammation by siRNA mediated knockdown. We also examined IK patient tear samples for MIF levels. Infection with A. flavus or A. castellanii induced IL-8 and TNF-α responses in HCECs and THP-1 macrophages but to different levels. Our preliminary human data showed that the level of secreted MIF protein was elevated in IK patient tear, however, MIF secretion by the two cell types were strikingly different in-vitro, under both normal and infected conditions. We found that HCECs released MIF constitutively, which was significantly inhibited with infection, whereas THP-1 macrophages were stimulated to release MIF during infection. MIF gene expression remained largely unaffected by infection in both the cell lines. Although MIF in HCECs appeared to be intracellularly captured during infection, MIF knockdown in HCECs associated with a partial reduction of the IL-8 and TNF-α expression produced by either of the pathogens, suggesting a pro-inflammatory role for MIF in HCECs, independent of its canonical cytokine like function. In contrast, MIF knockdown in THP-1 macrophages accompanied a dramatic increase in IL-8 and TNF-α expression during A. castellanii infection, while the responses to A. flavus infection remained unchanged. These data imply a host cell-type and pathogen specific distinction in the MIF- related inflammatory signaling and MIF as a potential selective immunomodulatory target in infectious keratitis.

Ocular Surface Allostasis-When Homeostasis Is Lost: Challenging Coping Potential, Stress Tolerance, and Resilience

The loss of ocular surface (OS) homeostasis characterizes the onset of dry eye disease. Resilience defines the ability to withstand this threat, reflecting the ability of the ocular surface to cope with and bounce back after challenging events. The coping capacity of the OS defines the ability to successfully manage cellular stress. Cellular stress, which is central to the outcome of the pathophysiology of dry eye disease, is characterized by intensity, continuity, and receptivity, which lead to the loss of homeostasis, resulting in a phase of autocatalytic dysregulation, an event that is not well-defined. To better define this event, here, we present a model providing a potential approach when homeostasis is challenged and the coping capacities have reached their limits, resulting in the stage of heterostasis, in which the dysregulated cellular stress mechanisms take over, leading to dry eye disease. The main feature of the proposed model is the concept that, prior to the initiation of the events leading to cellular stress, there is a period of intense activation of all available coping mechanisms preventing the imminent dysregulation of ocular surface homeostasis. When the remaining coping mechanisms and resilience potential have been maximally exploited and have, finally, been exceeded, there will be a transition to manifest disease with all the well-known signs and symptoms, with a shift to allostasis, reflecting the establishment of another state of balance. The intention of this review was to show that it is possibly the phase of heterostasis preceding the establishment of allostasis that offers a better chance for therapeutic intervention and optimized recovery. Once allostasis has been established, as a new steady-state of balance at a higher level of constant cell stress and inflammation, treatment may be far more difficult, and the potential for reversal is drastically decreased. Homeostasis, once lost, can possibly not be fully recovered. The processes established during heterostasis and allostasis require different approaches and treatments for their control, indicating that the current treatment options for homeostasis need to be adapted to a more-demanding situation. The loss of homeostasis necessarily implies the establishment of a new balance; here, we refer to such a state as allostasis.

Topical application of calcitonin gene-related peptide as a regenerative, antifibrotic, and immunomodulatory therapy for corneal injury

Calcitonin gene-related peptide (CGRP) is a multifunctional neuropeptide abundantly expressed by corneal nerves. Using a murine model of corneal mechanical injury, we found CGRP levels in the cornea to be significantly reduced after injury. Topical application of CGRP as an eye drop three times daily accelerates corneal epithelial wound closure, reduces corneal opacification, and prevents corneal edema after injury in vivo. We then used a series of in vitro and in vivo techniques to investigate the mechanisms underlying CGRP's functions. CGRP promotes corneal epithelial cell migration, proliferation, and the secretion of laminin. It reduces TGF-β1 signaling and prevents TGF-β1-mediated stromal fibroblast activation and tissue fibrosis. CGRP reduces corneal endothelial cell apoptosis and death, preserves cell density and morphology, and promotes their pump function, thus reducing edema. Lastly, CGRP reduces neutrophil infiltration, macrophage maturation, and the production of inflammatory cytokines in the cornea. Taken together, our results show that corneal nerve-derived CGRP plays a cyto-protective, pro-regenerative, anti-fibrotic, and anti-inflammatory role in corneal wound healing. Given that current treatment options for corneal injury and opacity are scarce, CGRP has significant therapeutic potential in this area of unmet medical needs. In addition, our results highlight the critical role of sensory nerves in ocular surface homeostasis and injury repair.

New Trends in Pathology: From Cell Morphology to Molecular Medicine

After Rudolf Virchow's pioneering works, technological advances boosted the scientific interest in this research field, which nowadays is still far from extinguished [...].

Novel Peptides with Dual Properties for Treating Pseudomonas aeruginosa Keratitis: Antibacterial and Corneal Wound Healing

The corneal epithelium is a layer in the anterior part of eye that contributes to light refraction onto the retina and to the ocular immune defense. Although an intact corneal epithelium is an excellent barrier against microbial pathogens and injuries, corneal abrasions can lead to devastating eye infections. Among them, Pseudomonas aeruginosa-associated keratitis often results in severe deterioration of the corneal tissue and even blindness. Hence, the discovery of new drugs able not only to eradicate ocular infections, which are often resistant to antibiotics, but also to elicit corneal wound repair is highly demanded. Recently, we demonstrated the potent antipseudomonal activity of two peptides, Esc(1-21) and its diastereomer Esc(1-21)-1c. In this study, by means of a mouse model of P. aeruginosa keratitis and an in vivo corneal debridement wound, we discovered the efficacy of these peptides, particularly Esc(1-21)-1c, to cure keratitis and to promote corneal wound healing. This latter property was also supported by in vitro cell scratch and ELISA assays. Overall, the current study highlights Esc peptides as novel ophthalmic agents for treating corneal infection and injury, being able to display a dual function, antimicrobial and wound healing, rarely identified in a single peptide at the same micromolar concentration range.

Phosphatidylglycerol to Treat Chronic Skin Wounds in Diabetes

This review proposes the use of dioleoylphosphatidylglycerol (DOPG) to enhance diabetic wound healing. Initially, the characteristics of diabetic wounds are examined, focusing on the epidermis. Hyperglycemia accompanying diabetes results in enhanced inflammation and oxidative stress in part through the generation of advanced glycation end-products (AGEs), in which glucose is conjugated to macromolecules. These AGEs activate inflammatory pathways; oxidative stress results from increased reactive oxygen species generation by mitochondria rendered dysfunctional by hyperglycemia. These factors work together to reduce the ability of keratinocytes to restore epidermal integrity, contributing to chronic diabetic wounds. DOPG has a pro-proliferative action on keratinocytes (through an unclear mechanism) and exerts an anti-inflammatory effect on keratinocytes and the innate immune system by inhibiting the activation of Toll-like receptors. DOPG has also been found to enhance macrophage mitochondrial function. Since these DOPG effects would be expected to counteract the increased oxidative stress (attributable in part to mitochondrial dysfunction), decreased keratinocyte proliferation, and enhanced inflammation that characterize chronic diabetic wounds, DOPG may be useful in stimulating wound healing. To date, efficacious therapies to promote the healing of chronic diabetic wounds are largely lacking; thus, DOPG may be added to the armamentarium of drugs to enhance diabetic wound healing.

Sterile Corneal Infiltrates following Cataract Surgery: Case Series

We report a case series of 26 eyes of 26 patients undergoing planned cataract surgery from December 2021 to March 2022, who were diagnosed as having whitish round infiltrates in the surgical corneal incisions. The infiltrates were detected at the first check after 5-8 days from cataract surgery and were located either within the main corneal incision and/or in the smaller incisions. Corneal infiltrates (CIs) were single or multiple, without epithelial defects, and painless. All infiltrates were initially treated with full topical antibiotic coverage, in order to control eventual and serious postsurgical infection. However, at daily checks, the clinical course of CIs suggested a sterile etiology. For this reason, steroidal topical treatment was maintained for a long time with slow tapering until complete remission of the CIs. All infiltrates resolved completely in around 30-40 days. The surgical instruments and the sterilization process were scrutinized. A white amorphous material was found mainly on non-disposable anterior chamber cannulas and on irrigation/aspiration tips. Disposable cannulas were adopted, and machinery for cleaning and sterilization procedures were reviewed, with specific reference to water softener renewal. Thanks to these precautions, CIs never occurred again. Finally, our hypothesis was an immune corneal reaction to amorphous deposit on cannula tips. This case series describes a previously unknown complication of cataract surgery and our experience might be useful for other surgeons.