Soluble CD163 and interleukin-6 are increased in aqueous humour from patients with endothelial rejection of corneal grafts

Role of Immune Cell Diversity and Heterogeneity in Corneal Graft Survival: A Systematic Review and Meta-Analysis

Corneal transplantation is one of the most successful forms of solid organ transplantation; however, immune rejection is still a major cause of corneal graft failure. Both innate and adaptive immunity play a significant role in allograft tolerance. Therefore, immune cells, cytokines, and signal-transduction pathways are critical therapeutic targets. In this analysis, we aimed to review the current literature on various immunotherapeutic approaches for corneal-allograft rejection using the PubMed, EMBASE, Web of Science, Cochrane, and China National Knowledge Infrastructure. Retrievable data for meta-analysis were screened and assessed. The review, which evaluated multiple immunotherapeutic approaches to prevent corneal allograft rejection, showed extensive involvement of innate and adaptive immunity components. Understanding the contribution of this immune diversity to the ocular surface is critical for ensuring corneal allograft survival.

Urine soluble CD163 (sCD163) as biomarker in glomerulonephritis: stability, reference interval and diagnostic performance

Objectives

Soluble (s) CD163 is a well-established macrophage biomarker, and recent data suggests urine sCD163 to reflect disease activity in crescentic glomerulonephritis (GN). Other types of GN may also be associated with glomerular inflammation but the potential usefulness of urine sCD163 as a general biomarker of GN remains unaddressed.

Methods

An in-house sCD163 enzyme-linked immunosorbent assay (ELISA) was validated for urinary use and compared to a frequently used commercial ELISA. The pre-analytical stability of urine sCD163 was assessed and a reference interval was established according to the CLSI guidelines using specimens from 253 healthy individuals. Urine samples from 64 patients with different types of renal disorders were also analysed.

Results

Urine sCD163 was highly stable during storage. An upper reference limit of 5.1 μg/L (1.9 μg/mmol, normalised to creatinine) was established using the in-house ELISA. Urine sCD163 was generally increased in GN patients (3.9 μg/mmol, p<0.0001, AUROC=0.97) and decreased upon treatment, but did not perform better than urine albumin (AUROC=1.00). Patients with proliferative GN had higher urine sCD163/albumin (p=0.0001) ratio. The commercial assay had a higher detection limit, and patient levels were 4-6 times lower than in the in-house assay.

Conclusions

Urine sCD163 is a stable biomarker that can be measured with acceptable accuracy using our in-house ELISA. Its pre-analytical characteristics makes it a reliable biomarker and our findings point towards the use of urine sCD163 as a biomarker of specific subtypes of GN.

The Innate Immune Cell Profile of the Cornea Predicts the Onset of Ocular Surface Inflammatory Disorders

Ocular surface inflammatory disorder (OSID) is a spectrum of disorders that have features of several etiologies whilst displaying similar phenotypic signs of ocular inflammation. They are complicated disorders with underlying mechanisms related to several autoimmune disorders, such as rheumatoid arthritis (RA), Sjögren’s syndrome, and systemic lupus erythematosus (SLE). Current literature shows the involvement of both innate and adaptive arms of the immune system in ocular surface inflammation. The ocular surface contains distinct components of the immune system in the conjunctiva and the cornea. The normal conjunctiva epithelium and sub-epithelial stroma contains resident immune cells, such as T cells, B cells (adaptive), dendritic cells, and macrophages (innate). The relative sterile environment of the cornea is achieved by the tolerogenic properties of dendritic cells in the conjunctiva, the presence of regulatory lymphocytes, and the existence of soluble immunosuppressive factors, such as the transforming growth factor (TGF)-β and macrophage migration inhibitory factors. With the presence of both innate and adaptive immune system components, it is intriguing to investigate the most important leukocyte population in the ocular surface, which is involved in immune surveillance. Our meta-analysis investigates into this with a focus on both infectious (contact lens wear, corneal graft rejection, Cytomegalovirus, keratitis, scleritis, ocular surgery) and non-infectious (dry eye disease, glaucoma, graft-vs-host disease, Sjögren’s syndrome) situations. We have found the predominance of dendritic cells in ocular surface diseases, along with the Th-related cytokines. Our goal is to improve the knowledge of immune cells in OSID and to open new dimensions in the field. The purpose of this study is not to limit ourselves in the ocular system, but to investigate the importance of dendritic cells in the disorders of other mucosal organs (e.g., lungs, gut, uterus). Holistically, we want to investigate if this is a common trend in the initiation of any disease related to the mucosal organs and find a unified therapeutic approach. In addition, we want to show the power of computational approaches to foster a collaboration between computational and biological science.

The Balance of Th1/Th2 and LAP+Tregs/Th17 Cells Is Crucial for Graft Survival in Allogeneic Corneal Transplantation

Purpose

CD4+LAP+ T cells are newly discovered regulatory T cells (Tregs). The aim of this study is to investigate the balance of Th1/Th2 and LAP+Tregs/Th17 in mice after allogeneic corneal transplantation.

Methods

A total of 65 mice received orthotopic penetrating transplantation. According to the survival scores of the grafts, the mice were divided into the rejection group and the survival group 3 weeks after transplantation. Th1, Th2, Th17, and regulatory T cells in the ipsilateral drainage lymph nodes and spleens were measured with flow cytometry. The related cytokines in aqueous humor were also analyzed.

Results

The frequencies of Foxp3+Tregs, GARP+Tregs, and LAP+Tregs in the survival group were significantly higher than those in the rejection group. And the expression trend of CD4+LAP+ T cells and CD4+GARP+ T cells was consistent. The level of IFN-γ, TNF, IL-6, and IL-17A markedly increased in aqueous humor during corneal allograft rejection. The ratio of Th1/Th2 and Th17/LAP+Tregs significantly increased in the rejection group at the 3rd week after corneal transplantation.

Conclusion

LAP+Tregs might be regarded as substitute for Foxp3+Tregs. The balance of Th1/Th2 and LAP+Tregs/Th17 is crucial for corneal allograft survival.

Soluble CD163 and soluble mannose receptor predict survival and decompensation in patients with liver cirrhosis, and correlate with gut permeability and bacterial translocation

BACKGROUND

Activated hepatic macrophages play a key role in inflammation and fibrosis progression in chronic liver disease.

AIM

To assess the prognostic value of soluble (s)CD163 and mannose receptor (sMR) in cirrhotic patients and explore associations with markers of intestinal permeability (lactulose-mannitol ratio, diamine oxidase), bacterial translocation (endotoxin, lipopolysaccharide-binding protein) and markers of systemic immune activation (interleukin-6, interleukin-8, sCD14).

METHODS

We prospectively investigated 101 cirrhotic patients (Child-Pugh class A: n = 72, Child-Pugh classes B and C: n = 29) and 31 healthy controls. Patients were observed for a median follow-up of 37 months.

RESULTS

Median plasma levels of sCD163 and soluble mannose receptor were significantly elevated in cirrhotic patients (P < .001) and increased with disease severity (sCD163 in healthy controls = 1.3, Child-Pugh class A = 4.2, Child-Pugh classes B and C = 8.4 mg/L; sMR in healthy controls = 15.8, Child-Pugh class A = 36.5, Child-Pugh classes B and C = 66.3 μg/dL). A total of 21 patients died during the observation period. Patients with sCD163 levels above 5.9 mg/L showed significantly reduced survival (survival rate after 36 months: 71% versus 98%, P < .001). Patients with soluble mannose receptor levels above 45.5 μg/dL developed significantly more complications of cirrhosis within 12 months (73% versus 9%, P < .001). Furthermore, both variables correlated with the lactulose-mannitol ratio, diamine oxidase, lipopolysaccharide and interleukin-8.

CONCLUSION

Our data demonstrate the prognostic value of sCD163 in predicting long-term survival in patients with liver cirrhosis and identify soluble mannose receptor as a prognostic marker for occurrence of cirrhosis-associated complications. The correlation between gut barrier dysfunction and activation of macrophages points towards a link between them.

Bilateral Alterations in Corneal Nerves, Dendritic Cells, and Tear Cytokine Levels in Ocular Surface Disease

This review summarizes the recent literature regarding corneal imaging in human subjects using in vivo confocal microscopy. It also covers the recent literature on corneal immune cells, nerves, and tear cytokine levels in ocular surface diseases as well as corneal immune privilege. The significance of interactions between corneal immune cells and nerves in health, neurotrophic keratopathy, and infectious keratitis is discussed. Furthermore, bilateral alterations of immune cells and nerves in clinically unilateral corneal diseases and the link to changes of tear cytokines or neuropeptide levels in contralateral eyes are described. Recent studies reported increased density and morphologic changes of corneal dendritic cells in ocular surface disease that correlated with a decrease in subbasal nerve and corneal nerve density, suggesting potential interactions between the immune and nervous systems in the cornea. Although the relevance of tear cytokines is poorly understood, tear cytokines might have an important role in the pathogenesis of ocular surface diseases. In humans and experimental animal models, alterations in immune cells, cytokines, and immunomodulatory neuropeptide levels in contralateral eyes might mediate the incidence of bilateral infectious keratitis and loss of immune privilege of the cornea in bilateral corneal transplantation or neurotrophic keratopathy cases. The discovery of bilateral alterations of immune cells and nerves in ocular surface diseases is considered the missing link between the immune and nervous systems in the cornea, and demonstrates how studies of animal models and humans aid our understanding of human corneal disease phenomena.

Clinical significance of sCD163 and its possible role in asthma (Review)

Macrophages exert important functions in the balance and efficiency of immune responses, and participate in innate and adaptive immunity. The proinflammatory actions of macrophages are implicated in autoimmune diseases. Unlike classically activated M1 macrophages, the alternatively activated cluster of differentiation (CD)163⁺ and CD206⁺ M2 macrophages are involved in tissue repair and wound healing, and use oxidative metabolism to support their long-term functions. CD163 is a member of the scavenger receptor superfamily, categorized into class B, and its soluble(s) form, sCD163, is a marker of activated M2 macrophages. CD163 is selectively expressed in cells of the monocyte and macrophage lineages; however, its biological role has yet to be elucidated. The expression of sCD163 is markedly induced by anti-inflammatory mediators, such as glucocorticoids and interleukin-10, whereas it is inhibited by proinflammatory mediators, such as interferon-γ. These findings suggest that CD163 may serve as a potential target for the therapeutic modulation of inflammatory responses. The concentration of sCD163 in blood is associated with acute and chronic inflammatory processes in autoimmune disorders of connective tissue, fat metabolism and cardiovascular diseases, and it can be used for the assessment of cancer prognosis. A role for sCD163 in the pathogenesis of asthma has also been proposed. The present review serves to present the available knowledge concerning the implication of sCD163 in the pathophysiological mechanisms of asthma, and evaluate its potential as a biomarker and possible therapeutic target for asthma.

Monocyte CD163 is altered in association with diabetic complications: possible protective role

The scavenger receptor CD163 is exclusively expressed by monocyte/macrophages and is shed by matrix metalloproteinases (MMPs) and neutrophil elastase (ELA2) as soluble CD163 (sCD163). Monocyte phenotype is altered in diabetes, but the relationship among monocyte CD163, sCD163, and diabetic complications is not known and was investigated in this study. Blood was obtained from patients with diabetes for >10 yr and mice with diabetes for ≤20 wk. Blood from people and mice without diabetes acted as controls. The percentage of CD163⁺ monocytes and monocyte CD163 mRNA was determined by flow cytometry and qRT-PCR, respectively. Plasma sCD163, MMPs, and ELA2 were measured by ELISA. The ability of glucocorticoids to stimulate isolated monocyte CD163 expression was also investigated. The percentage of CD163⁺ monocytes was significantly decreased and sCD163 significantly increased (both P < 0.05) in patients with diabetes with complications compared to those without complications. Plasma ELA2 and MMP-3 were also increased (P < 0.05), but CD163 mRNA was unaltered. sCD163 correlated with worsening renal function, as determined by eGFR (r = -0.48, P < 0.05). In diabetic mice, increased sCD163 at wk 5 and decreased percentage of CD163⁺ monocytes at wk 10 preceded alteration in kidney collagen IV mRNA at wk 20 (all P < 0.05). In vitro incubation of monocytes in anti-inflammatory glucocorticoid increased the percentage of CD163⁺ monocytes (P < 0.05). In people, higher sCD163 and decreased percentage of CD163⁺ monocytes were consistent with increased monocyte activation and shedding. The murine data indicated that these changes preceded the development of diabetic complications. Taken together, these results suggest that higher circulating percentage of CD163⁺ monocytes may have anti-inflammatory effects and may protect from development of diabetic complications.

Role of Human Corneal Stroma-Derived Mesenchymal-Like Stem Cells in Corneal Immunity and Wound Healing

Corneal tissue regeneration is of crucial importance for maintaining normal vision. We aimed to isolate and cultivate human corneal stroma-derived mesenchymal stem-like cells (CSMSCs) from the central part of cadaver corneas and study their phenotype, multipotency, role in immunity and wound healing. The isolated cells grew as monolayers in vitro, expressed mesenchymal- and stemness-related surface markers (CD73, CD90, CD105, CD140b), and were negative for hematopoietic markers as determined by flow cytometry. CSMSCs were able to differentiate in vitro into fat, bone and cartilage. Their gene expression profile was closer to bone marrow-derived MSCs (BMMSCs) than to limbal epithelial stem cells (LESC) as determined by high-throughput screening. The immunosuppressive properties of CSMSCs were confirmed by a mixed lymphocyte reaction (MLR), while they could inhibit proliferation of activated immune cells. Treatment of CSMSCs by pro-inflammatory cytokines and toll-like receptor ligands significantly increased the secreted interleukin-6 (IL-6), interleukin-8 (IL-8) and C-X-C motif chemokine 10 (CXCL-10) levels, as well as the cell surface adhesion molecules. CSMSCs were capable of closing a wound in vitro under different stimuli. These cells thus contribute to corneal tissue homeostasis and play an immunomodulatory and regenerative role with possible implications in future cell therapies for treating sight-threatening corneal diseases.

Correlation between human tear cytokine levels and cellular corneal changes in patients with bacterial keratitis by in vivo confocal microscopy

PURPOSE

We investigated bilateral tear cytokine levels in patients with unilateral bacterial keratitis (BK) as associated with in vivo confocal microscopic (IVCM) alterations in corneal nerves and dendritiform immune cells (DCs).

METHODS

A total of 54 (13 BK, 13 contralateral, 28 healthy controls) tear samples was collected prospectively and analyzed by multiplex microbeads assay. The IVCM of the central cornea was performed on the same day, and assessed for corneal nerve and DC alterations.

RESULTS

Interleukin-1β, IL-6, and IL-8 were significantly elevated only in affected eyes (66.6 ± 26.8, 7174 ± 2430, and 810 ± 315 ρg/mL, respectively; P = 0.04, P < 0.001, and P < 0.001, respectively), compared to healthy controls (13.0 ± 4.0, 171.8 ± 32.1, and 56.5 ± 33.8 ρg/mL). Levels of chemokine ligand 2 (CCL-2), IL-10, and IL-17a were elevated only in contralateral eyes (813 ± 478, 86.7 ± 38.3, and 3350 ± 881 ρg/mL, respectively; P = 0.02, P = 0.01, and P = 0.04, respectively), compared to controls (73.7 ± 25.3, 17.5 ± 4.9, and 1350 ± 337 ρg/mL). Triggering receptor expressed on myeloid cells (TREM)-1 was significantly elevated in affected (551 ± 231 ρg/mL, P = 0.02) and contralateral unaffected (545 ± 298 ρg/mL, P = 0.03) eyes compared to controls (31.3 ± 12.4 ρg/mL). The density of DCs was significantly increased in affected (226.9 ± 37.3 cells/mm(2), P < 0.001) and unaffected (122.3 ± 23.7 cells/mm(2), P < 0.001) eyes compared to controls (22.7 ± 5.9 cells/mm(2)). Sub-basal nerve density significantly decreased in affected (3337 ± 1615 μm/mm(2), P < 0.001) and contralateral (13,230 ± 1635 μm/mm(2), P < 0.001) eyes compared to controls (21,200 ± 545 μm/mm(2)). Levels of IL-1β, IL-6, and IL-8 were significantly correlated with DC density (R = 0.40, R = 0.55, and R = 0.31, all P < 0.02) and nerve density (R = -0.30, R = -0.53, and R = -0.39, all P < 0.01).

CONCLUSIONS

Proinflammatory tear cytokines are elevated bilaterally in patients with unilateral BK, and are correlated strongly with alterations in DCs and nerve density as detected by IVCM.

Strategies for local gene therapy of corneal allograft rejection

Penetrating keratoplasty is the most common type of tissue transplant in humans. Irreversible immune rejection leads to loss of vision and graft failure. This complex immune response further predisposes future corneal transplants to rejection and failure. A diverse armamentarium of surgical and pharmacologic tools is available to improve graft survival. In this review, we will discuss the various gene therapeutic strategies aimed at potentiating the anterior chamber-associated immune deviation to extend graft survival.

Association between the haptoglobin and heme oxygenase 1 genetic profiles and soluble CD163 in susceptibility to and severity of human malaria

Intravascular hemolysis is a hallmark event in the immunopathology of malaria that results in increased systemic concentrations of free hemoglobin (Hb). The oxidation of Hb by free radicals causes the release of heme, which amplifies inflammation. To circumvent the detrimental effects of free heme, hosts have developed several homeostatic mechanisms, including the enzyme haptoglobin (Hp), which scavenges cell-free Hb, the monocyte receptor CD163, which binds to Hb-Hp complexes, and heme oxygenase-1 (HO-1), which degrades intracellular free heme. We tested the association between these three main components of the host response to hemolysis and susceptibility to malaria in a Brazilian population. The genetic profiles of the HMOX1 and Hp genes and the plasma levels of a serum inflammatory marker, the soluble form of the CD163 receptor (sCD163), were studied in 264 subjects, including 78 individuals with symptomatic malaria, 106 individuals with asymptomatic malaria, and 80 uninfected individuals. We found that long (GT)n repeats in the microsatellite polymorphism region of the HMOX1 gene, the Hp2 allele, and the Hp2.2 genotype were associated with symptomatic malaria. Moreover, increased plasma concentrations of heme, Hp, HO-1, and sCD163 were associated with susceptibility to malaria. The validation of these results could support the development of targeted therapies and aid in reducing the severity of malaria.

Simultaneous quantification of 17 immune mediators in aqueous humour from patients with corneal rejection

PURPOSE

To simultaneously quantitate and compare the concentrations of 17 immune mediators: (1) the cytokines interleukin-1beta, IL-2, IL-4, IL-5, IL-6, IL-7, IL-10, IL-12p70, IL-13, IL-17, tumour necrosis factor-alpha, interferon-gamma; (2) the growth factors granulocyte-monocyte colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF), and (3) the chemokines CXCL-8, monocyte chemoattractant protein-1, and macrophage inflammatory protein-1beta in aqueous humour from patients with corneal rejection and patients with a non-inflammatory condition in the anterior chamber.

METHODS

Aqueous humour was obtained by paracentesis of the anterior chamber in 14 patients with corneal rejection, three patients with cataract and six patients with Fuchs' endothelial dystrophy. Simultaneous quantitation of 17 mediators in 25 micro l aqueous humour from each patient was performed by employing a highly sensitive Luminex 100 multiplex array assay.

RESULTS

All 17 immune mediators were detected in aqueous humour from rejection patients. The ranges of the immune mediators were determined. The immune mediators were significantly increased in aqueous humour from rejection patients compared with that from other patients.

CONCLUSIONS

The Luminex 100 multiplex array assay is very efficient in simultaneous quantitation of multiple immune mediators in small volumes of aqueous humour. A total of 17 immune mediators were increased in aqueous humour from rejection patients. This underlines the complex immunological interactions of the rejection process.

Enhanced release of IL-6 and IL-8 into tears in various anterior segment eye diseases

OBJECTIVE

To determine the levels of interleukin 6 (IL-6) and interleukin 8 (IL-8/CXCL-8) in tears collected from the eyes of normal individuals and of patients with different irritative eye diseases, in order to acquire information on the immunological changes occurring during the early postoperative period following various forms of eye surgery, including penetrating keratoplasty (PKP).

METHODS

IL-6 and IL-8 levels were measured with the aid of human ultrasensitive ELISA kits in the non-stimulated tears of patients in the early postoperative period following PKP or cataract operation, and of patients with acute bacterial conjunctivitis or with a corneal foreign body. The IL-6 and IL-8 concentrations, the total amounts released in a given time and the rates of their release were calculated.

RESULTS

A significant increase in IL-6 release was observed in all patient groups compared with the normal controls (p < or = 0.003). The IL-8 release levels were significantly higher in the tears of all patient groups (p < or = 0.03), except for the cataract operation group, where the IL-8 release was not significantly higher (p = 0.053) than in the control samples. No significant differences in IL-6 or IL-8 release were observed when the various patient groups were compared with each other.

CONCLUSION

The release of IL-6 and IL-8 into the tears is enhanced in various anterior segment eye diseases, and this may be used as an indicator of various inflammatory reactions in the early postoperative period.