Role of the V2R-ßarrestin-Gßγ complex in promoting G protein translocation to endosomes.

Classically, G protein-coupled receptors (GPCRs) promote signaling at the plasma membrane through activation of heterotrimeric Gαßγ proteins, followed by the recruitment of GPCR kinases and ßarrestin (ßarr) to initiate receptor desensitization and internalization. However, studies demonstrated that some GPCRs continue to signal from internalized compartments, with distinct cellular responses. Both ßarr and Gßγ contribute to such non-canonical endosomal G protein signaling, but their specific roles and contributions remain poorly understood. Here, we demonstrate that the vasopressin V2 receptor (V2R)-ßarr complex scaffolds Gßγ at the plasma membrane through a direct interaction with ßarr, enabling its transport to endosomes. Gßγ subsequently potentiates Gαs endosomal translocation, presumably to regenerate an endosomal pool of heterotrimeric Gs. This work shines light on the mechanism underlying G protein subunits translocation from the plasma membrane to the endosomes and provides a basis for understanding the role of ßarr in mediating sustained G protein signaling.

Rahnella Aquatilis Endophthalmitis after Intravitreal Injection in an Immunocompetent Patient.

PURPOSE: To present a novel case of exogenous Rahnella aquatilis endophthalmitis following an intravitreal injection. METHODS: Case report. RESULTS: A 74-year-old male presented with acute progressive vision loss and pain in the left eye, 5 days after an intravitreal injection for diabetic macular edema. The patient was diagnosed with exogenous endophthalmitis and empirically treated with intravitreal injections of vancomycin and ceftazidime as well as topical and oral ciprofloxacin. In follow up two days later, the patient was treated with preoperative povidone-iodine followed by prompt vitrectomy with additional vancomycin and ceftazidime due to pharmacy sterile hood issues that delayed antibiotic availability. Microbiological cultures and two mass spectrometry identification tests confirmed the diagnosis of exogenous Rahnella aquatilis endophthalmitis. Despite the presence of scattered retinal hemorrhagic infarcts involving the macula and subsequent full-thickness atrophic macular holes seen in follow up, the patient achieved a favorable anatomical and functional outcome of BCVA 20/80 at 1 year of follow-up. CONCLUSION: This case highlights the occurrence of exogenous Rahnella aquatilis endophthalmitis following an intravitreal injection for diabetic macular edema. Prompt diagnosis and treatment produced a favorable outcome relative to other typical Gram-negative Enterobacteriaceae organisms.

An Ophthalmology Virtual Externship during the COVID-19 Pandemic: A Pilot Study.

Background The evolution of medical school curricula, characterized by truncated preclinical periods and reduced emphasis on ophthalmology, presents formidable obstacles to early exposure for aspiring medical students. The constraints imposed by the coronavirus disease 2019 pandemic further exacerbated the limitations on opportunities, compelling the implementation of innovative initiatives aimed at augmenting students' ophthalmology education through virtual means. Purpose This article assesses the impact of an Ophthalmology Virtual Externship (OVE) on medical students' knowledge, interest, confidence, and seeking mentorship in ophthalmology. Materials and Methods A total of 76 students voluntarily participated in the program. The OVE encompassed four virtual sessions, facilitated by 4th year medical students employing a near-peer mentorship framework. The initiative was tailored for 2nd and 3rd year medical students and was conducted under the supervision of a faculty member. All participating students completed both pre- and postexternship surveys utilizing a 7-point Likert scale to gauge their levels of interest, confidence, and inclination toward mentorship opportunities in the field of ophthalmology. Furthermore, assessments of ophthalmology knowledge were administered prior to and subsequent to the externship participation. The degree of satisfaction derived from the OVE experience was also evaluated. Results Participation in the OVE significantly elevated confidence in knowledge ( p < 0.001) and mentorship interest ( p = 0.029). Ophthalmology knowledge test scores also notably improved post-OVE across all participants, irrespective of prior experience ( p < 0.001), with the most significant increase observed among 2nd and 3rd year students ( p < 0.0001). After OVE participation, 73% of students expressed intent to pursue ophthalmology opportunities, including mentorship or research. The OVE received an average Likert score of 6.35 out of 7 for student satisfaction. Conclusion The OVE serves as a virtual learning instrument beneficial for 2nd and 3rd year students with a proclivity for ophthalmology, offering a means to circumvent curriculum-related constraints. Moreover, given the decline in formal ophthalmic education, our study contributes to future research assessing the effectiveness of an OVE in addressing ophthalmic knowledge gaps among all medical students.

The Warburg effect alters amino acid homeostasis in human retinal endothelial cells: implication for proliferative diabetic retinopathy.

Proliferative diabetic retinopathy (PDR) remains a leading cause of blindness despite progress in screening and treatment. Recently, the Warburg effect, a metabolic alteration affecting amino acid (AA) metabolism in proliferating cells, has drawn attention regarding its role in PDR. This study aimed to investigate the impact of the Warburg effect on AA metabolism in human retinal endothelial cells (HRECs) subjected to PDR-associated risk factors and validate the findings in patients with PDR. In vitro experiments exposed HRECs to high glucose (HG) and/or hypoxia (Hyp), known inducers of the Warburg effect. The HG + Hyp group of HRECs exhibited significant differences in non-essential AAs with aliphatic non-polar side chains, mainly driven by elevated glycine concentrations. Pathway enrichment analysis revealed several glycine metabolism-related pathways significantly altered due to the Warburg effect induced by HG + Hyp. Crucially, vitreous humor samples from PDR patients displayed higher glycine levels compared to non-diabetic and diabetic patients without PDR. The odds ratio for PDR patients with glycine levels above the cut-off of 0.0836 µM was 28 (p = 0.03) compared to non-PDR controls. In conclusion, this study provides mechanistic insights into how a specific Warburg effect subtype contributes to glycine accumulation in PDR and supports glycine's potential as a biomarker for PDR pathogenesis.

Patient Clinical Outcomes in Standalone Versus a Combined Ophthalmology-rheumatology Uveitis Clinic.

BACKGROUND: To evaluate uveitis care outcomes in standalone versus a combined ophthalmology-rheumatology clinic. METHODS: Participants were patients aged 18 years and older with a minimum 12-month history of chronic uveitis prior to being referred to the combined uveitis clinic at Kresge Eye Institute and who were treated in the combined clinic for at least 6 months. Best corrected visual acuity (BCVA), objective markers of inflammation, and achieving targeted dose of immunomodulatory therapy (IMT) were compared in the cohort of uveitis patients 6 months prior to and after the initial evaluation in the combined clinic. RESULTS: Sixty-six percent of study participants were female with a mean age of 51.5 years. BCVA improved from 0.58 logMAR (Snellen: ~20/74) at the initial combined clinic visit to 0.50 logMAR (Snellen: ~20/63) 6 months after the first combined visit (p = 0.0137). The establishment of the combined uveitis clinic led to higher frequency of patients at target dose of IMT: an increase from 49.0% at 6 months prior to the combined visit to 70.1.4% and 79.8% at the initial combined visit and 6 months after the combined visit, respectively. CONCLUSION: A combined model of management for chronic uveitis patients wherein rheumatological services are coupled with ophthalmic care leads to improvement in patient clinical outcomes and achieving target therapy.

Hypoxia-Inducible Factor-1α in Rods Is Neuroprotective Following Retinal Detachment.

Purpose: Following retinal detachment (RD) photoreceptors (PRs) sustain hypoxic stress and eventually die. Hypoxia-inducible factor-1α (HIF-1α) plays a central role in cellular adaptation to hypoxia. The purpose of this study is to determine the necessity of HIF-1α on PR cell survival after RD. Methods: Experimental RD was created in mice by injection of hyaluronic acid (1%) into the subretinal space. Mice with conditional HIF-1α knockout in rods (denoted as HIF-1αΔrod) were used. HIF-1α expression in retinas was measured real-time polymerase chain reaction (RT-PCR) and Western blotting. PR cell death after RD was evaluated using TUNEL assay. Optical coherence tomography (OCT) and histology were used to evaluate retinal layer thicknesses and PR cell densities. A hypoxia signaling pathway PCR array was used to examine the expression of HIF-1α target genes after RD. Results: HIF-1α protein levels were significantly increased after RD, and depletion of HIF-1α in rods blunted this increase. A compensatory increase of HIF-2α protein was observed in HIF-1αΔrod mice. Conditional knockout (cKO) of HIF-1α in rods did not lead to any morphologic change in attached retinas but resulted in significantly increased PR cell loss after RD. HIF-1α cKO in rods altered the responses to retinal detachment for 25 out of 83 HIF-1α target genes that were highly enriched for genes involved in glycolysis. Conclusions: Rod-derived HIF-1α plays a key role in the PR response to RD, mediating the transcriptional activity of a battery of genes to promote PR cell survival.

Accuracy of intravitreal injection volume for aflibercept pre-filled syringe and BD Luer-Lok one-milliliter syringe.

BACKGROUND: To evaluate the accuracy of intravitreal injection volume of the pre-filled syringe (PFS) in which aflibercept is packaged compared to the BD Luer-Lok 1-mL syringe. METHODS: Ophthalmologists injected their typical intravitreal volume for aflibercept using either the PFS or BD Luer-Lok 1-mL syringe for 5 times each. The injected fluid was weighed using a micro-scale and converted to volume. The volume of fluid injected was also evaluated when the 0.05 mL line on the PFS was lined up to the tip or base of the dome-shaped plunger. RESULTS: Injection volume was measured for 12 physicians. The average injected fluid volume was 74.22 ± 15.87 µL for PFS and 53.42 ± 4.61 µL for the BD Luer-Lok 1-mL syringe (p < 0.0001). The average deviation in volume injected for the PFS was higher compared to the BD Luer-Lok 1-mL syringe (11.36 µL vs. 3.35 µL, p < 0.0001). When the PFS was lined up with the tip of the dome-shaped plunger at the 0.05-mL line, the average injected volume was 71.03% higher. CONCLUSIONS: The intravitreal injection volume and variability using the new PFS were significantly higher than the volume injected using the BD Luer-Lok 1-mL syringe previously used, potentially leading to higher rates of visually significant elevation of intraocular pressures.

Self-management of depression among Chinese community individuals: A cross-sectional study using the transtheoretical model.

PURPOSE: To investigate the self-management of depression among members of a Chinese community. DESIGN AND METHODS: A cross-sectional survey was conducted in Wuhan. The Depression Prevention and Management Survey was used to identify 429 participants' stage of change, perceived benefits, process of change and self-efficacy, based on the transtheoretical model perspective. FINDINGS: A majority of participants (69.0%) were at the inactive stage of depression self-management. The mean score of the process of change was 87.62 (SD = 24.83). ANOVA analysis showed gender, education, and family function were significant influencing factors in the process of change. PRACTICE IMPLICATIONS: Mental health nurses need to target their approach to the level of the individual based on the transtheoretical model to assist them to enhance their awareness and motivation. More consideration should be given to gender, education, and family function in the context of depression self-management.

Autosomal Dominant Vitreoretinochoroidopathy With a Novel BEST1 Mutation and a Review of Reported Mutations.

Here we describe a patient with atypical presentation of autosomal dominant vitreoretinochoroidopathy (ADVIRC) with a novel missense mutation in BEST1 gene and briefly review reported ADVIRC-associated genetic mutations. The patient is a 71-year-old African American female who presented with progressively worsening blurry vision bilaterally over the course of 40 years, with significant deterioration in both peripheral and central vision in the past five years. Her anterior segment exam was unremarkable. Fundoscopic examination showed confluent, demarcated areas of pigmentary chorioretinal atrophy in the mid-periphery of the retina with sparing of the macula in both eyes. Optical coherence tomography (OCT) of the lesions revealed flattening of the fovea with an elevation of the inner retinal structures and outer plexiform layer, and peripheral retinal thinning and loss of retinal structures with choroid hyperreflectivity, consistent with peripheral chorioretinal atrophy. Genetic testing identified a heterozygous c.830C>T, p.(T277M) mutation located on exon 7 of the BEST1 gene. This patient represents an atypical presentation of ADVIRC with more posterior involvement, and this case is associated with a novel missense mutation in the BEST1 gene.

Conditional Knock out of High-Mobility Group Box 1 (HMGB1) in Rods Reduces Autophagy Activation after Retinal Detachment.

After retinal detachment (RD), the induction of autophagy protects photoreceptors (PR) from apoptotic cell death. The cytoplasmic high-mobility group box 1 (HMGB1) promotes autophagy. We previously demonstrated that the deletion of HMGB1 from rod PRs results in a more rapid death of these cells after RD. In this work, we tested the hypothesis that the lack of HMGB1 accelerates PR death after RD due to the reduced activation of protective autophagy in the retina after RD. The injection of 1% hyaluronic acid into the subretinal space was used to create acute RD in mice with a rhodopsin-Cre-mediated conditional knockout (cKO) of HMGB1 in rods (HMGB1Δrod) and littermate controls. RD sharply increased the number of apoptotic cells in the outer nuclear layer (ONL), and this number was further increased in HMGB1Δrod mouse retinas. The activation of autophagy after RD was reduced in the HMGB1Δrod mouse retinas compared to controls, as evidenced by diminished levels of autophagy regulatory proteins LC3-II, Beclin1, ATG5/12, and phospho-ATG16L1. The cKO of HMGB1 in rods increased the expression of Fas and the Bax/Bcl-2 ratio in detached retinas, promoting apoptotic cell death. In conclusion, endogenous HMGB1 facilitates autophagy activation in PR cells following RD to promote PR cell survival and reduce programmed apoptotic cell death.

SnapShot: The Regulatory Genome.

Enhancers switch genes on and off in response to a variety of intrinsic and external cellular signals. They are the cornerstone of gene regulation and the most pervasive constituents of the regulatory genome. Sequence polymorphisms in enhancer DNAs are a major source of population diversity and predilection to disease. To view this SnapShot, open or download the PDF.

Erratum: Evolution of π

This corrects the article DOI: 10.1103/PhysRevLett.109.152301.

Loss of High-Mobility Group Box 1 (HMGB1) Protein in Rods Accelerates Rod Photoreceptor Degeneration After Retinal Detachment.

Purpose: Retinal detachment (RD) disrupts the nutritional support and oxygen delivery to photoreceptors (PRs), ultimately causing cell death. High-mobility group box 1 (HMGB1) can serve as an extracellular alarmin when released from stressed cells. PRs release HMGB1 after RD. The purpose of this study was to investigate the relationship between HMGB1 and PR survival after RD. Methods: Acute RD was created by injection of hyaluronic acid (1%) into the subretinal space in C57BL/6 mice and mice with a rhodopsin-Cre-mediated conditional knockout (cKO) of HMGB1 in rods (HMGB1ΔRod). Immunofluorescence (IF) in retinal sections was used to localize HMGB1, rhodopsin, and Iba-1 proteins. Optical coherence tomography and electroretinography were used to quantify retinal thickness and function, respectively. The morphology of the retina was assessed by hematoxylin and eosin. Results: HMGB1 protein was localized to the nuclei of all retinal neurons, including PRs, with cones staining more intensely than rods. HMGB1 protein was also found in the inner and outer segments of cones but not rods. Creation of RD caused a dramatic increase of HMGB1 protein IF in rods. cKO of HMGB1 in rods did not affect retinal structure or function. However, after RD, loss of rods and reduction in the thickness of the outer nuclear layer were significantly increased in the HMGB1ΔRod retinas as compared to the control. Interestingly, depletion of HMGB1 in rods did not affect the activation and mobilization of microglia/macrophages normally seen after RD. Conclusions: Increased HMGB1 expression in stressed rods may represent an intrinsic mechanism regulating their survival after RD.

Corruption in Health Systems: The Conversation Has Started, Now Time to Continue it Comment on "We Need to Talk About Corruption in Health Systems".

Holistic and multi-disciplinary responses should be prioritized given the depth and breadth through which corruption in the healthcare sector can cover. Here, taking the Peruvian context as an example, we will reflect on the issue of corruption in health systems, including corruption with roots within and outside the health sector, and ongoing efforts to combat it. Our reflection of why corruption in health systems in settings with individual and systemic corruption should be an issue that is taken more seriously in Peru and beyond aligns with broader global health goals of improving health worldwide. Addressing corruption also serves as a pragmatic approach to health system strengthening and weakens a barrier to achieving universal health coverage and Sustainable Development Goals related to health and justice. Moreover, we will argue that by pushing towards a practice of normalizing the conversation about corruption in health has additional benefits, including expanding the problematization to a wider audience and therefore engaging with communities. For young researchers and global health professionals with interests in improving health systems in the early career stages, corruption in health systems is an issue that could move to the forefront of the list of global health challenges. This is a challenge that is uniquely multi-disciplinary, spanning the health, economy, and legal sectors, with wider societal implications.

Transcriptome of Tetranychus urticae embryos reveals insights into Wolbachia-induced cytoplasmic incompatibility.

The endosymbiont Wolbachia is known for manipulating host reproduction in selfish ways. However, the molecular mechanisms have not yet been investigated in embryos. Here, we found that Wolbachia had no effect on the number of deposited eggs in Tetranychus urticae Koch (Acari: Tetranychidae) but caused two types of reproductive manipulation: killing uninfected female embryos via cytoplasmic incompatibility (CI) and increasing the hatching ratio of infected female embryos. RNA sequencing analyses showed that 145 genes were differentially expressed between Wolbachia-infected (WI) and Wolbachia-uninfected (WU) embryos. Wolbachia infection down-regulated messenger RNA (mRNA) expression of glutathione S-transferase that could buffer oxidative stress. In addition, 1613 and 294 genes were identified as CI-specific up-/down-regulated genes. Compared to WU and WI embryos, embryos of CI cross strongly expressed genes involved in transcription, translation, tissue morphogenesis, DNA damage and mRNA surveillance. In contrast, most of the genes associated with energy production and metabolism were down-regulated in the CI embryos compared to the WU and WI embryos, which provides some clues as to the cause of death of CI embryos. These results identify several genes that could be candidates for explaining Wolbachia-induced CI. Our data form a basis to help elucidate the molecular consequences of CI in embryos.

Peptide-mediated cationic micelles drug-delivery system applied on a VEGFR3-overexpressed tumor.

Copolymers as a kind of drug delivery carrier always lack targeting efficiency. So a peptide conjugated to a drug delivery system has attracted much attention for tumor-targeted nanomedicine. Thus, we here report a conjugation compound consisting of a copolymer (PEG-b-PLL) and a peptide (Cys-Ile-Gln-Pro-Phe-Tyr-Pro, CP7). For receptor-mediated endocytosis by this peptide, the CP7-PEG-b-PLL conjugation significantly enhanced the chemotherapeutic efficacy as a potent nanocarrier compared with free DOX. The CP7-PEG-b-PLL exhibited excellent pharmacokinetic behavior via a radioactive iodine-131 (I) tracing method. With this, the CP7-PEG-b-PLL/DOX system showed better tumor growth inhibition when studied on A549 cell lines and subcutaneous tumor models, but with less toxicity than free DOX. All these results suggest that the CP7-modified drug cationic micelles could represent a novel platform for successful drug delivery toward VEGFR3-overexpressed tumors.

Vitreous Cytokine Expression and a Murine Model Suggest a Key Role of Microglia in the Inflammatory Response to Retinal Detachment.

Purpose: Retinal detachment (RD) separates the retina from the underlying retinal pigment epithelium, resulting in a gradual degeneration of photoreceptor (PR) cells. It is known that RD also results in an inflammatory response, but its contribution to PR degeneration is unknown. In this study we examine the inflammatory responses to RD in patient vitreous and validate a mouse experimental RD as a model of this phenomenon. Methods: Multiplex bead arrays were used to examine cytokine levels in vitreous samples from 24 patients with macula-off rhegmatogenous retinal detachment (RRD) undergoing reattachment surgery and from 10 control patients undergoing vitrectomy for vitreous opacities or epiretinal membrane. Activation of the innate immune response was then examined in a mouse model of RD. Results: Twenty-eight factors were significantly increased in vitreous from RD patients versus controls. Notable were the cytokines MCP-1 (CCL2), IP-10 (CXCL10), fractalkine (CX3CL1), GRO (CXCL1), MDC (CCL22), IL-6, and IL-8, which all exhibited relatively high concentrations and several-fold increases in the vitreous of RD patients. Concentrations of various analytes correlated with a range of clinical variables such as duration of detachment and visual acuity. Retinal detachment in the mouse resulted in cytokine mRNA expression changes consistent with human RD vitreous results, as well as microglial proliferation and migration toward the outer retina. Conclusions: The findings suggest that an inflammatory response involving microglia is a component of the reaction to retinal detachment that may impact visual acuity after surgical repair and that mouse experimental RD can serve as a model to study this effect.

ISG15 in Host Defense Against Candida albicans Infection in a Mouse Model of Fungal Keratitis.

Purpose: ISG15, a di-ubiquitin-like protein, is critical for controlling certain viral and bacterial infections. We sought to determine if ISG15 plays a role in corneal innate immunity against Candida albicans (C. albicans) using a C57BL/6 (B6) mouse model of human fungal keratitis. Methods: Scarified corneas of adult B6 mice were pretreated with TLR5 ligand flagellin and then inoculated with C. albicans. The expression of ISG15 and other genes involved in ISG15 conjugation (ISGylation) was determined by real-time PCR. ISG15 expression and distribution in infected corneas were assessed by immunohistochemistry. ISGylation was examined by Western blotting. siRNA knockdown and recombinant ISG15 were used to elucidate the effects of ISG15 on controlling fungal keratitis by clinical scoring, fungal number plate counting, ELISA cytokine determination, and polymorphonuclear leukocytes (PMN) infiltration measurement. Results: Heat-killed C. albicans induced expression of ISG15, and hBD2 was markedly enhanced by flagellin-pretreatment in cultured human primary corneal epithelial cells (CECs). In vivo, C. albicans infection induced the expression of ISG15, ISGylation-associated genes (UBE1L, UBCH8, and HERC5), and ISGylation in mouse CECs, all of which were enhanced by flagellin-pretreatment. siRNA knockdown of ISG15 increased keratitis severity, dampened flagellin-induced protection, and greatly suppressed the expressions of ISGylation enzymes, IFN-γ, but not CXCL2 in B6 mouse CECs. Recombinant ISG15, on the other hand, enhanced corneal innate immunity against C. albicans and suppressed infection-induced IL-1ß, but not IL-Ra expression. ISG15 alone induced the expression of IL-1Ra, CXCL10, and CRAMP in mouse CECs. ISG15 was upregulated and secreted in cultured human CECs in response to challenge in a type 1 IFN-dependent manner. Conclusions: Our data, for the first time, demonstrate that ISG15 acts as an immunomodulator in the cornea and plays a critical role in controlling fungal keratitis.

De Novo Computational Design for Development of a Peptide Ligand Oriented to VEGFR-3 with High Affinity and Long Circulation.

The overexpression of VEGFR-3 is correlated with a worse prognosis in lung cancer and has been regarded as a rational target for specific drug delivery. Here, VEGFR-3 homing peptide library was efficiently established by computational design. Strong fluorescent signals of selected peptides were observed in A549 cells, but much weaker in other cells. The positive immunostaining overlapped with VEGFR-3 confirmed high affinity and selectivity of one novel peptide (CP-7). In addition, cell uptake of FITC-CP-7 peptide was significantly blocked by coinjection of excess CP-7 peptide. After labeled with 131I, the profile of pharmacology and biodistribution could be traced in vivo. The 131I-radiolabeled CP-7 peptide conjugates were >85% stable in serum over 4 h and exhibited a specific uptake of 18.04 ± 2.04% ID/g at 0.5 h after injection to high VEGFR-3 expressing A549 tumor mice. More importantly, lower uptake concentration in heart (1.06 ± 0.15% ID/g) after 2 h demonstrated the safety of peptide in vivo. The high uptake in the kidneys revealed that renal clearance was the main route of 131I-CP-7 peptide elimination from the body. Lower accumulation of 131I-CP-7 peptide in VEGFR-3 negative HeLa tumor mice further indicated that CP-7 peptide exhibited a higher tumor-homing efficiency. These studies provided a straightforward analytical access to design and screen bioactive peptide based on protein structure and revealed that CP-7 peptide represented a promising homing peptide of VEGFR-3-positive cancer in vitro and in vivo which could be used as a novel target molecule to achieve efficient drug delivery.

IL-24 Promotes Pseudomonas aeruginosa Keratitis in C57BL/6 Mouse Corneas.

The aim of this study was to elucidate the expression and functions of IL-24 in C57BL/6 mouse corneas in response to Pseudomonas aeruginosa infection. Among IL-20R cytokines, only IL-24 was induced at both mRNA and protein levels by infection at early time points. The upregulation of IL-24 was dampened by flagellin pretreatment, which protects the corneas from microbial infection. Time course studies revealed bimodal early and later peaks of IL-24 expression, a pattern shared with suppressor of cytokine signaling (SOCS)3 but not IL-1ß or IL-6. Silencing of IL-24 enhanced S100A8/A9 expression and suppressed SOCS3, IL-1ß, IL-1RN, and matrix metalloproteinase 13 expression at 6 h postinfection. Downregulation of the IL-24 signaling pathway significantly reduced the severity of keratitis, whereas rIL-24 exacerbated P. aeruginosa-mediated tissue destruction. In vitro, rIL-1ß induced the expression of SOCS3, IL-24, IL-1ß, and IL-6 in primary cultured human corneal epithelial cells. rIL-24, alternatively, stimulated the expression of SOCS3, but not the others. In conclusion, IL-24 promotes P. aeruginosa keratitis through the suppression of early protective mucosal immunity, culminating in increased severity of P. aeruginosa keratitis.