Substance P affects growth factors in Pseudomonas aeruginosa-infected mouse cornea

PURPOSE

This study analyzed the influence of substance P (SP) on growth factors related to wound healing in mice in the presence of infectious keratitis.

METHODS

Naturally resistant mice were injected intraperitoneally with SP or phosphate-buffered saline and infected with Pseudomonas aeruginosa, and corneal messenger RNA (mRNA) levels of growth factors and apoptosis genes were tested. Enzyme-linked immunosorbent assay determined the protein levels, whereas immunohistochemistry tested the distribution, macrophage phenotype, and cell quantitation. In vitro, macrophages were stimulated with lipopolysaccharide (LPS; with or without SP) and mRNA levels of proinflammatory and antiinflammatory cytokines and apoptosis genes were tested.

RESULTS

After SP, epidermal growth factor mRNA and protein levels were disparately regulated early, with no differences later in the disease. Hepatocyte growth factor and fibroblast growth factor-7 mRNA and protein levels were increased after SP treatment. Enumerating dual-labeled stromal cells revealed no difference between SP-treated versus phosphate-buffered saline-treated groups in the percentage of epidermal growth factor-labeled fibroblasts or macrophages, but there were significant increases in both hepatocyte growth factor- and fibroblast growth factor-7-labeled cells. Type 2 (M2) macrophages and caspase-3 mRNA levels were decreased, whereas B-cell lymphoma-2 mRNA expression was increased after SP treatment. In vitro, mRNA levels of several proinflammatory cytokines and B-cell lymphoma-2 were elevated, whereas transforming growth factor β was decreased after macrophage stimulation with SP (with LPS) over LPS alone. (Mice: n = 105 control; 105 experimental.)

CONCLUSIONS

These data show that treatment with SP in infectious keratitis elevates growth factors but also adversely affects the disease by enhancing the inflammatory response and its sequelae.

BALB/c and C57BL6 mouse strains vary in their ability to heal corneal epithelial debridement wounds

Genetically engineered mice are usually produced on a mixed genetic background and can be derived from several mouse strains including 129SvJ, C57BL6, and BALB/c. To determine whether differences in recurrent corneal epithelial erosions (RCEEs), corneal epithelial stem cell deficiency (CESCD), and cell migration rate vary between two different mouse strains (BALB/c and C57BL6), 8-week mice were subjected to 1.5 (small) or 2.8mm (large) manual debridement wounds and allowed to heal for 4 weeks. Syndecan-1 (sdc-1) null mice backcrossed seven generations onto a BALB/c genetic background were also included in the RCEE and CESCD studies to permit comparisons between genotypes within a single strain. After sacrifice, corneas were assessed for the presence of recurrent erosions; no fewer than 15 corneas were used for each strain or genotype studied. Data show that the frequency of recurrent erosions after small wounds was 81+/-9% in the C57BL6 mice, 73+/-2% in the BALB/c mice, and 32+/-6% in sdc-1 null mice. Neither strain developed CESCD after small wounds. The frequency of erosions after large wounds was greater (88+/-8%) in the C57BL6 mice compared to BALB/c (60+/-2%), and sdc-1 null mice (32+/-5%). Four weeks after the large wounds, fixed, flat mounted corneas were assessed for evidence of CESCD with antibodies against the conjunctival keratin K8 and the goblet cell marker, the mucin Muc5AC. The frequency of CESCD 4 weeks after the large wounds was significantly greater in the C57BL6 mice than in the BALB/c or sdc-1 null mice. To assess cell migration rates, corneas were subjected to 1.5mm wounds and allowed to heal for 12, 15, 18, 21, and 24h. After sacrifice, corneas were stained with Richardson stain (BALB/c) or propidium iodide (C57BL6) to assess reepithelialization rates. While reepithelialization rates were similar for the early times after wounding, by 24h the C57BL6 corneas had healed faster: 16 of 30 corneas from the C57BL6 mice were closed compared to 9 of 30 of the BALB/c wounds. BALB/c corneas appeared larger overall compared to C57BL6 corneas; measurements of the overall mass of the enucleated eyes and diameters of the flat-mounted corneas confirmed that C57BL6 eyes and corneas were 6.8% and 4.4% smaller respectively than those of BALB/c mice even though the masses of the two mouse strains at 8 weeks of age were identical. Using BrdU to label dividing cells, we found that 18 h after wounding, C57BL6 and BALB/c corneal epithelia showed similar numbers of proliferating cells. To determine if the enhanced corneal epithelial cell migration rate seen in the C57BL6 mice was specific to the cornea, we conducted time-lapse studies to assess random cell migration rates in vitro using primary cultures of mouse epidermal keratinocytes. Consistent with the in vivo data, epidermal keratinocytes derived from BALB/c mice migrated 60% slower than C57BL6 cells. These data prove that strain-specific differences in cell migration rate in vivo are present in the cornea and are accompanied by differences in the frequencies of recurrent erosions and corneal epithelial stem cell deficiency.

ST2 Is Essential for Th2 Responsiveness and Resistance toPseudomonas aeruginosaKeratitis

PURPOSE

To elucidate the role of ST2, a member of the TLR/IL-1R (TIR) superfamily, in protecting against Pseudomonas aeruginosa keratitis in BALB/c mice.

METHODS

ST2 mRNA and protein expression levels were tested by real-time PCR and Western-blot in C57BL/6 (B6; susceptible) versus BALB/c (resistant) mice before and after P. aeruginosa (strain 19660; American Type Culture Collection, Philadelphia, PA) challenge. Infected BALB/c mice also were tested after subconjunctival injection with recombinant murine (rm)ST2 or PBS. Disease was monitored by clinical score, slit lamp, bacterial plate count, a myeloperoxidase (MPO) assay to measure polymorphonuclear neutrophil (PMN) infiltrate, real-time RT-PCR, and ELISA.

RESULTS

ST2 mRNA and protein were constitutively expressed in the uninfected normal corneas of both mouse groups. ST2 levels in the cornea of BALB/c compared with B6 mice were elevated significantly at 1 to 3 days post infection (PI), peaked at 3 and decreased at 5 days PI. BALB/c mice treated with rmST2 showed increased corneal opacity and perforation (at 5 days PI) when compared with PBS controls. rmST2- versus PBS-injected mice exhibited increased bacterial load, PMN infiltrate, and higher corneal mRNA levels for IL-1beta, MIP-2, IL-6, IL-1R1, and Th1-type cytokine such as IFN-gamma. Protein levels for IL-1beta, MIP-2, and IL-6 also were significantly upregulated, whereas the Th2 cytokines IL-4 (mRNA), IL-5 (mRNA), and IL-10 (mRNA and protein) were significantly reduced.

CONCLUSIONS

ST2 is critical in resistance to P. aeruginosa keratitis, functioning to reduce corneal infection (bacterial load) and inflammation by negatively regulating proinflammatory cytokines and inhibiting type-1 immunity, but upregulating type-2 cytokine production, particularly IL-10.

Two patients with severe corneal disease in KID syndrome

PURPOSE

To report two independent Japanese patients with keratitis, ichthyosis, and deafness (KID) syndrome and severe corneal disorder.

DESIGN

Observational case reports.

METHODS

Clinical observation of a 5-year-old boy (Patient 1) and a 64-year-old man (Patient 2) with KID syndrome, presenting prominent corneal diseases. Molecular genetic assessment of the GJB2 gene encoding connexin-26 was performed.

RESULTS

Patient 1 had bilateral diffuse superficial punctuate keratopathy with severe corneal neovascularization. He had a missense mutation of the GJB2 gene. Patient 2 had bilateral corneal stromal keratitis and right corneal ulceration with rupture of the Descemet membrane. He did not have any pathologic mutation of the GJB2 gene. The area of palisades of Vogt was diminished and tear production reduced in both patients. Topical eye drops, and corticosteroid or antibiotics, respectively, relieved them effectively.

CONCLUSION

The impaired ocular surface regulating system might be a cause of corneal disease in KID syndrome and it can be treated by eye drops.

Bilateral Corneal Anesthesia Associated With Diaphragmatic Paralysis, Ovarian Failure, and Developmental Delay

PURPOSE

To describe two siblings with bilateral corneal anesthesia associated with multiple systemic abnormalities.

DESIGN

Interventional case report.

METHODS

A 38-year-old Hispanic woman was seen for bilateral corneal ulcers, exposure keratitis, hemorrhagic retinopathy, and multiple systemic abnormalities. A younger sibling with similar but milder findings was also examined. Medical and genetic evaluation was investigated in these two siblings with bilateral decreased sensation and multiple abnormalities from a consanguineous union.

RESULTS

Examination of the patient showed bilateral corneal anesthesia, and multiple systemic abnormalities included diaphragmatic paralysis, ovarian failure, multiple thrombotic cerebrovascular accidents, pedal edema, mandibular hypoplasia, and developmental delay. Milder findings were seen in a sibling. Corneal ulcers were stabilized after treatment that included bandage contact lens, pressure patching, topical antibiotics, and tarsorrhaphy.

CONCLUSIONS

The combination of corneal anesthesia and systemic abnormalities, with parental consanguinity, suggests an inherited syndrome.

Tumour necrosis factor alpha and interleukin 6 gene expression in keratocytes from patients with rheumatoid corneal ulcerations

BACKGROUND/AIMS

Ultrastructural alterations in the stroma adjacent to corneal perforations have previously been reported in patients with longstanding rheumatoid arthritis. Since patients with rheumatoid arthritis often present upregulation of proinflammatory cytokines in serum and in synovial fluid, it was of interest to analyse the gene expression of these cytokines-for example, tumour necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6), in corneal samples from patients with corneal ulcerations and/or perforations associated with rheumatoid arthritis.

METHODS

Corneal samples from seven patients with corneal ulcerations and/or perforations associated with rheumatoid arthritis were collected in 4% paraformaldehyde in "RNAse-free" conditions. Paraffin sections were fixed on silan coated slides and further analysed by systematic non-radioactive in situ hybridisation, using specific gene probes for TNF-alpha and IL-6 labelled with digoxigenin (DIG). Detection of hybrids was carried out by using a commercially available DIG detection system.

RESULTS

Whereas an extended TNF-alpha gene expression could be clearly observed in the keratocytes surrounding the corneal ulcerations and/or perforations from five of the seven analysed patients, all seven patients presented clearly positive results for an extended IL-6 gene expression in the analysed tissue samples.

CONCLUSIONS

Alterations in corneal cells surrounding ulcerations and/or perforations in patients with rheumatoid arthritis may occur with implication for inflammatory processes. Upregulation of the proinflammatory cytokines TNF-alpha and IL-6 may modify the production of metalloproteinases in the corresponding cells resulting in collagenolytic corneal damage.

[Hereditary, recurrent corneal erosions]

The review presents a clinical case of 40 years old female patient with bilateral recurrent corneal erosions (r.c.e.), without an obvious cause. It is relevant to mention the present of the r.c.e. in her family during 4 generations. The acute corneal lesions looked like a "map-dot-fingerprint" dystrophy and 3 weeks later cornea became normal.

Gene expression of pro-inflammatory cytokines and chemokines in mouse eye infected with Pseudomonas aeruginosa

Ocular infection with Pseudomonas aeruginosa triggers extensive host inflammatory response and corneal damage. The purpose of present study was to investigate the gene expression of pro-inflammatory mediators interleukin (IL)-1 beta, IL-6, tumour necrosis factor-alpha (TNF-alpha),macrophage inflammatory protein (MIP)-2 and cytokine-induced neutrophil chemoattractant (KC) in the mouse eye challenged with P. aeruginosa. Scratched mouse corneas were infected with three phenotypes of P. aeruginosa individually. Total RNA was extracted from mouse eyes at 4 h, 8 h,16 h and 24 h post-challenge. Single stranded cDNA was synthesized from total RNA by reverse transcription and then subjected to polymerase chain reaction (PCR) using specific primers for IL-1 beta, IL-6, TNF-alpha, MIP-2 and KC. Results revealed three patterns of cytokines and chemokines expression in response to ocular infection with three phenotypes of P. aeruginosa. Ocular infection with the invasive strain induced the highest levels of IL-1 beta, IL-6, MIP-2 and KC mRNA, followed by the infection with the cytotoxic strain. Ocular infection with the CLARE strain induced the lowest levels of IL-1 beta, IL-6, MIP-2 and KC mRNA. The expression of TNF-alpha mRNA was very low and irregular following P. aeruginosa challenge. These data indicate that over-expression of pro-inflammatory cytokines and chemokines may represent a vigorous immune response and therefore may contribute to corneal damage during P. aeruginosa infection.

Does the shared epitope genotype influence either the susceptibility to or the phenotype of corneal melting?

PURPOSE

To investigate the role of the shared epitope alleles in determining susceptibility to and the phenotype of corneal melting in patients with rheumatoid arthritis (RA).

METHODS

The HLA class 1 and 2 genotype was determined for 17 patients with rheumatoid-associated comeal melting by the phototyping method. HLA-DR4 subtyping was performed by PCR sequence-based typing. The frequency of all the shared epitope alleles and, in particular, of the higher-risk *0401 and *0404 alleles, was compared with healthy controls and unrelated RA patients, with and without extra-articular manifestations. A comparison was also made between the shared epitope genotype of the corneal melt patients and local, ocular disease characteristics.

RESULTS

Thirteen (76%) patients with corneal melt possessed at least one shared epitope allele and 5 (29%) possessed two alleles. The dominant alleles were variants of the DR4 family, notably the *0401, *0404 and *0408 alleles. Both the allele frequency and a double dose of shared epitope alleles were more common in the three RA patient groups than in the healthy, control group (p < 0.005). Although the frequency of the higher-risk alleles was similar in the three RA patient group, a trend existed for a double dose of higher-risk alleles to be more common in the patients with either corneal melt or other extra-articular manifestations (p > 0.2). No association was found between the number or type of shared epitope alleles and any of the ocular disease characteristics studied.

CONCLUSIONS

The results of this study suggest that the shared epitope alleles do not influence the ocular disease phenotype of corneal melt in RA patients. Shared epitope determination of RA patients may help to identify those susceptible to either corneal melt or other extra-articular disease. RA patients with a double dose of higher-risk alleles may have an increased risk of corneal melt.

[Keratopathy as a sign of multifocal congenital sensory polyneuropathy. A case report]

PATIENT

A 63-year-old female with bilateral recurrent corneal ulcerations for 10 years, suffered from vascularisation of the cornea and absence of corneal sensitivity. Other symptoms were multifocal hypoaesthesia with hypalgesia of hands and legs, generalised lack of deep tendon reflexes, absence of somato-sensory evoked potentials (SSEP) and of sensory nerve action potentials (SNAP) in these regions. A sural biopsy demonstrated extreme lack of myelinated fibres. Acquired causes for polyneuropathy were excluded.

THERAPY

Subsequent to local ocular treatment we carried out a perforating corneal transplantation of the left eye because of corneal scars. This had to be repeated 2 years later because of vascularisation of the transplant. The visual function of the left eye could be stabilised at values between 0.2 and 1/50.

CONCLUSION

Anamnesis and clinical symptoms of the patient are compatible with the diagnosis of hereditary sensory neuropathy type II (HSN II) affecting the trigeminal nerves. In patients with neuropathy and impaired corneal sensitivity, a favourable prognosis may be achieved by a corneal transplant.

Cloning and sequence analysis of human and bovine corneal antigen (CO-Ag) cDNA: identification of host-parasite protein calgranulin C

PURPOSE

The primary structure of a cornea-associated antigen (CO-Ag) has been identified and has been implicated in the pathogenesis of Mooren's ulcer. The study designs were to isolate full-length clones encoding CO-Ag from a bovine and a human corneal cDNA library so that complete sequence analyses might further define the possible role of this protein in Mooren's ulcer.

METHODS

DNA fragments of bovine and human CO-Ag were generated using unique oligonucleotide primers and reverse transcription polymerase chain reaction. These fragments were used as probes to obtain cDNA clones from a bovine and a human corneal cDNA libraries. The clones with the longest cDNA inserts were selected for sequence analyses. Human cDNA fragment was digested with Stu I and Hind III and cloned into a expression vector, pPROEXHT, at the same restriction enzyme sites. The plasmid was transformed into E. coli cells. Correct cloning and the full-length sequence of human CO-Ag were determined by sequencing the insert cDNA.

RESULTS

The bovine cDNA insert sequence was 273 nucleotides in length for the entire mRNA coding region, 212 nucleotides in the 5' untranslated region, 83 nucleotides in the 3' untranslated region and a poly(A) tail. The DNA base sequence of this clone also contained a standard initiation codon, termination codon, and the polyadenylation signal. This cDNA predicts a protein which contains 91 amino acids with a molecular weight of 10,584 daltons. Plasmid expression vector, pPROEXHT-CO-Ag, was constructed that direct the synthesis of human CO-Ag in E. coli as fusion protein. Human CO-Ag fusion protein was purified to 90% pure with a yield of 17.2 mg per liter of the bacterial cell lysate. The nucleotide sequence of the CO-Ag cDNA insert was completely identical to human neutrophil calgranulin C. The deduced amino acid sequence was completely identical to a Ca(2+)-binding protein isolated on the surface of filarial nematodes.

CONCLUSIONS

The isolation and analysis of cDNA clones containing the complete coding sequence of bovine and human CO-Ag proteins is reported. The proteins identified by deduced amino acid sequences demonstrate 100% sequence homology with human and bovine calgranulin C. Immune recognition of calgranulin C to a filarial nematode may lead to a hyperactive autoimmune response to CO-Ag in the cornea leading to a Mooren's ulcer.

[Apropos of a case of bilateral perforating corneal ulcer in a patient with Portugese amyloidosis]

PURPOSE

Corneal ulcer is a very rare clinical manifestation in hereditary familial amyloidosis of the Portuguese type, from which only one case has been reported previously. The case of a 35-year-old man illustrates the diagnostic findings and the difficulties encountered in understanding the physiopathology of such a complication.

PATIENT

The patient was referred by his general practician because of bilateral visual impairment since few days. Examination disclosed bilateral central perforating corneal ulceration. Corneal sensitivity was normal in both eyes, BUT (break-up time) was 2 sec. and Schirmer II test abolished.

RESULTS/CONCLUSION

Corneal ulceration is an unusual complication consecutive to a massive dry eye syndrome.

HLA-DR alleles and sterile ulcerative keratitis

Human leukocyte antigen-DR typing was performed on 18 unrelated white patients with sterile ulcerative keratitis (SUK) to determine whether these patients share common immunogenetic susceptibility genes. There was no statistically significant increase in any DR allele among the entire group of SUK patients. There was a trend in the frequency of DR1 in the rheumatoid arthritis (RA) patients (5 of 8, 63%) versus the non-RA patients (1 of 10, 10%), which was not statistically significant, possibly due to the small number of patients in the study. Screening patients with RA without known SUK from our RA register revealed one DR1-positive patient with an inactive peripheral marginal melt. These findings suggest a possible relationship between DR1 and RA sterile corneal melting, which will need to be confirmed with a larger study.

[Abnormal expression of HLA class II antigens in conjunctival epithelia in peripheral corneal ulcers]

Inflammatory mediators originating at the limbus seem to play an important role in the pathogenesis of peripheral corneal ulcers. In this paper, the immunohistological results of conjunctival biopsies of patients with corneal ulcers are reported. The most important result was that an abnormal HLA class II expression was found. The expression of HLA-DR was stronger than that of HLA-DQ and HLA-DP. A model of ulcer formation involving T-cells and lymphokines is presented.

[Hereditary recurrent erosion of the cornea]

Case report concerning a 14-year-old girl who, like her father and father's sister, is suffering from spontaneous, recurring of bilateral corneal erosions, the first symptoms occurred when she was nine. Her father suffered several attacks each year between the ages of 11 to 25, but has since been completely asymptomatic. An autosomal dominant mode of inheritance is assumed.

Acromutilating, paralyzing neuropathy with corneal ulceration in Navajo children

Four Navajo children had a mutilating neuropathy with severe motor involvement. The disorder appears to be recessively inherited and is present from the earliest observable age. Manifestations include severe anesthesia, corneal ulceration, painless fractures, acral mutilation, and weakness. Mental function is normal. Sural nerves are practically devoid of myelinated fibers that show no evidence of regeneration. Unmyelinated axons show degenerative and regenerative morphologic and histometric features. Onion bulb formation is absent. We believe this neuropathy is a distinct clinical entity.