Mediterranean diet and mortality risk in metabolically healthy obese and metabolically unhealthy obese phenotypes.

BACKGROUND: The Mediterranean diet has been consistently associated with reduced mortality risk. Few prospective studies have examined whether the benefits from a Mediterranean diet are equally shared by obese individuals with varying metabolic health. OBJECTIVE: The objective of this study was to investigate the association between Mediterranean diet, metabolic phenotypes and mortality risk in a representative obese US population. METHODS: Data from 1739 adults aged 20-88 years were analyzed from participants of the National Health and Nutrition Examination Survey III, 1988-1994 followed up for deaths until 31 December 2011 in a prospective cohort analysis. Mediterranean Diet Scores (MDS) were created to assess the adherence to Mediterranean diet. Participants were classified as metabolically healthy obese (MHO) phenotype (0 or 1 metabolic abnormality) or metabolically unhealthy obese (MUO) phenotype (two or more metabolic abnormalities), based on high glucose, insulin resistance, blood pressure, triglycerides, C-reactive protein and low high-density lipoprotein cholesterol. RESULTS: The MHO phenotype (n=598) was observed in 34.8% (s.e., 1.7%) of those who were obese (mean body mass index was 33.4 and 34.8 in MHO and MUO phenotypes, respectively). During a median follow-up of 18.5 years, there were 77 (12.9%) and 309 (27.1%) deaths in MHO and MUO individuals, respectively. In MHO individuals, the multivariable-adjusted hazard ratio (HR) of all-cause mortality in the highest tertile compared with the first tertile of MDS was 0.44 (95% confidence interval (CI), 0.26-0.75; P for trend <0.001), after adjustment for potential confounders. A five-point (1 s.d.) increment in the adherence to MDS was associated with a 41% reduction in the risk of all-cause mortality (HR, 0.59; 95% CI, 0.37-0.94). Similar findings were obtained when we restricted our analyses to those with or without prevalent diabetes mellitus and hypertension. We did not observe mortality risk reduction in either individuals with MUO phenotype or all obese participants combined. CONCLUSIONS: Adherence to a Mediterranean dietary pattern appears to reduce mortality in the MHO phenotype, but not among the MUO phenotype in an obese population.

Challenges of corneal infections.

INTRODUCTION: Ocular infections remain an important cause of blindness worldwide and represent a challenging public health concern. In this regard, microbial keratitis due to fungal, bacterial, or viral infection can result in significant vision loss secondary to corneal scarring or surface irregularity. Left untreated corneal perforation and endophthalmitis can result, leading to loss of the eye. Rigorously studied animal models of disease pathogenesis have provided novel information that suggests new modes of treatment that may be efficacious clinically and emerging clinical data is supportive of some of these discoveries. AREAS COVERED: This review focuses on advances in our understanding of disease pathogenesis in animal models and clinical studies and how these relate to improved clinical treatment. We also discuss a novel approach to treatment of microbial keratitis due to infection with these bacterial pathogens using PACK-CXL and recommend increased basic and clinical studies to address and refine the efficacy of this procedure. EXPERT COMMENTARY: Because resistance to antibiotics has developed over time to these bacterial pathogens, caution must be exercised in treatment. Attractive novel modes of treatment that hold new promise for further investigation include lipid based therapy, as well as use of small molecules that bind deleterious specific host responsive molecules and use of microRNA based therapies.

Association between Serum Antibodies to Oral Microorganisms and Hyperglycemia in Adults.

We conducted a cross-sectional analysis to evaluate the relationship between serum antibody titers against 19 selected oral microorganisms and measures of hyperglycemia in a large, nationally representative data set. The study population consisted of 7,848 participants from the National Health and Nutrition Examination Survey III (1988-1994) who were at least 40 yrs old, with complete serum IgG antibody data against 19 oral microorganisms. The 19 antibody titers were grouped into 4 categories via cluster analysis--orange-red, yellow-orange, orange-blue, and red-green--named to reflect predominant antibody titers against microorganisms in Socransky's classification scheme for oral microbes. Linear regression models weighted for complex survey design were used in which fasting blood glucose, fasting insulin, and HbA1c were outcomes and antibody cluster scores were exposures, adjusting for potential confounders. Higher orange-red cluster scores were associated with increased hyperglycemia, while higher orange-blue cluster scores were related with decreased hyperglycemia. A 1-unit-higher orange-red cluster score was associated with 0.46 mg/dL higher fasting blood glucose (p = .0038), and a 1-unit-higher orange-blue cluster score was associated with 0.34% lower HbA1c (p = .0257). Groups of antibody titers against periodontal microorganisms were associated with hyperglycemia independent of known risk factors.

Quality of life and lymphedema following breast cancer.

The aim of the study was to compare Quality of Life (QOL) of breast cancer patients with and without secondary lymphedema (SLE) using a cross-sectional design with a convenience sample. Research packets were mailed to 2088 breast cancer patients (BrCaPt). The QOL component of the study used the Quality of Life Instrument --Breast Cancer Patient Version for data collection. The sample (n = 537) was 12.9% African-American/Hispanic/Other (AA) and 87.1% European-American (EA). One hundred and twenty-two women (22.7%) reported SLE. Overall and subscale means were computed and ANOVA was determined for seven variables: age, marital status, educational level, race, type of surgery, time since diagnosis, and SLE. Women without SLE had a higher overall mean QOL score compared to women with SLE (p= 0.02). Women with a greater than high school education had a higher mean QOL score compared to women with high school or less education (p=0.05). SLE patients had poorer QOL in the physical (p<0.001), and social (p=0.004) subscales. Older women had a higher overall QOL compared to younger women (p<0.001). These results provide insight into the impact of SLE on women's QOL and pinpoint that physical and social well being are negatively influenced by SLE.

Further studies on the role of IL-12 in Pseudomonas aeruginosa corneal infection.

PURPOSE: Previous studies have shown that in Pseudomonas aeruginosa ocular infection, IL-12 drives a Th1 T-cell response and IFN-gamma production in susceptible (cornea perforates) C57BL/6 (B6) mice, and that after similar infection of resistant (cornea heals) BALB/c mice, no IL-12 is detectable in cornea at either the mRNA or protein levels. Therefore, the purpose of this study was to test whether BALB/c mice are capable of responding to exogenous IL-12 administration, and whether disease responsiveness following P. aeruginosa challenge is modified. METHODS: Immunostaining, RT/PCR, recombinant cytokine injection, and histopathology were used. Statistical analysis was performed using an unpaired, two-tailed Student's t-test. RESULTS: Injection of BALB/c mice with recombinant (r) IL-12 converted these normally resistant animals to the susceptible phenotype as evidenced by corneal perforation within 5-7 days after infection. RT-PCR analysis of the corneas of rIL-12 vs PBS/BSA-treated mice showed a significant increase in IFN-gamma and TNF-alpha mRNA levels in the rIL-12 vs PBS/BSA (vehicle)-treated mice at 3 and 5 days p.i. In addition, similar analysis of IL-4 mRNA levels showed decreased amounts of the cytokine in rIL-12 vs vehicle-treated mice. Injection of rIL-4 into susceptible B6 mice, however, failed to rescue these animals from corneal perforation following P. aeruginosa challenge. CONCLUSIONS: These data provide evidence that BALB/c mice can respond to exogenous IL-12, that the cytokine promotes susceptibility by increasing IFN-gamma and TNF-alpha production, with a concomitant reduction in IL-4 levels; and that injected rIL-4 fails to rescue susceptible B6 mice from corneal perforation after bacterial challenge.

MIP-1alpha regulates CD4+ T cell chemotaxis and indirectly enhances PMN persistence in Pseudomonas aeruginosa corneal infection.

The role of macrophage inflammatory protein-1alpha (MIP-1alpha) in cell infiltration into Pseudomonas aeruginosa-infected cornea and subsequent disease was examined. Greater amounts of the chemokine (protein and mRNA) were found in the infected cornea of susceptible B6 ("cornea perforates") versus resistant BALB/c ("cornea heals") mice from 1 to 5 days postinfection. Treatment of BALB/c mice with recombinant (r) MIP-1alpha exacerbated disease and was associated with an increased number of neutrophils (PMNs) in the cornea. Treatment of BALB/c mice with rMIP-1alpha also induced recruitment of activated CD4+ T cells into the affected cornea, converting resistant to susceptible mice. Depleting CD4+ T cells in r-treated BALB/c mice significantly decreased PMNs in cornea tissue, suggesting that T cells regulate persistence of PMNs at this site. In B6 mice, administration of neutralizing MIP-1alpha polyclonal antibody also significantly reduced PMN numbers and pathology. Collectively, evidence is provided that MIP-1alpha directly contributed to CD4+ T cell recruitment and indirectly to PMN persistence in the infected cornea.

Maintaining corneal integrity how the "window" stays clear.

The anterior surface of the eye is composed of the cornea, conjunctiva, and the zone between the two called the limbus. The cornea must maintain optical clarity to retain good vision. However, the ocular surface is vulnerable to trauma, microbial infection, and exposure to environmental toxins. This places the cornea, especially, at risk for disruptions of the epithelial barrier and subsequent immunopathological events. Cell-cell and cell-matrix attachment junctions incorporating adhesion molecules ensure that the epithelial barrier remains intact. Protein components of the basement membrane, including laminins, are vital to the adhesion of corneal epithelial cells to the underlying stroma and function to enhance the strength of the bond between epithelium and connective tissue. Epithelial cells also play an early and crucial role in the initiation of ocular surface responses should a potentially antigenic molecule enter into deeper corneal tissues. For example, epithelial cells may produce and release cytokines such as interleukin-1 (IL-1). The delicate balance between the matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are central to mechanisms regulating dissolution of the extracellular matrix that may be a consequence of infection or wound healing. Adhesion molecules, cytokines and chemokines, and MMPs and TIMPs thus participate in the corneal response to immunologic challenge or wounding. They may also be involved in corneal pathologies associated with genetic diseases, diabetes, and vitamin A deficiency. In addition these molecules are components of cellular pathways underlying the clinical complications often observed with contact lens wear and refractive surgeries used to improve visual acuity.

Human corneal epithelial extracellular matrix perlecan serves as a site for Pseudomonas aeruginosa binding.

PURPOSE: Previous data has shown that basement membrane associated perlecan serves as a binding site for Pseudomonas aeruginosa in the wounded mouse cornea. The current study determined whether it also provides a binding site for Pseudomonas aeruginosa in transformed human corneal epithelium. METHODS: Bacterial adherence to transformed human corneal epithelial cells grown in normal or in media containing various inhibitors of glycosaminoglycan synthesis was tested. Bacterial binding was similarly tested in wild-type and in mutant Chinese hamster ovary cell lines naturally deficient in glycosaminoglycan synthesis. Transformed human corneal epithelial extracellular matrix also was tested before and after treatment with anti-proteoglycan monoclonal antibodies or heparinase III before bacterial inoculation. Scanning electron microscopy was used to quantitate adherent bacteria. Intact transformed human corneal epithelial cells or extracellular matrix, the latter either treated or not treated with heparinase III or chondroitin ABC lyase were stained to localize perlecan. RESULTS: Examination of the binding of bacteria to transformed human corneal epithelial cells (normal media vs with inhibitors) and Chinese hamster ovary cell lines suggested that bacterial binding was not associated with the surface of either cell type. In contrast, anti-perlecan antibody, as well as heparinase III decreased the binding of bacteria to corneal extracellular matrix. Fluorescence staining localized perlecan to the extracellular matrix beneath the corneal epithelial cells. CONCLUSIONS: Perlecan localized to the extracellular matrix but not the apical surface of transformed human corneal epithelial cells, provides a binding site for Pseudomonas aeruginosa.

B7/CD28 costimulation is critical in susceptibility to Pseudomonas aeruginosa corneal infection: a comparative study using monoclonal antibody blockade and CD28-deficient mice.

Evidence suggests that Pseudomonas aeruginosa stromal keratitis and corneal perforation (susceptibility) is a CD4(+) T cell-regulated inflammatory response following experimental P. aeruginosa infection. This study examined the role of Langerhans cells (LC) and the B7/CD28 costimulatory pathway in P. aeruginosa-infected cornea and the contribution of costimulatory signaling by this pathway to disease pathology. After bacterial challenge, the number of LC infiltrating the central cornea was compared in susceptible C57BL/6 (B6) vs resistant (cornea heals) BALB/c mice. LC were more numerous at 1 and 6 days postinfection (p.i.), but were similar at 4 days p.i., in susceptible vs resistant mice. Mature, B7 positive-stained LC in the cornea and pseudomonas Ag-associated LC in draining cervical lymph nodes also were increased significantly p.i. in susceptible mice. To test the relevance of these data, B6 mice were treated systemically and subconjunctivally with neutralizing B7 (B7-1/B7-2) mAbs. Treatment decreased corneal disease severity and reduced significantly the number of B7-positive cells as well as the recruitment and activation of CD4(+) T cells in the cornea. IFN-gamma mRNA levels also were decreased significantly in the cornea and in draining cervical lymph nodes of mAb-treated mice. When CD28(-/-) animals were tested, they exhibited a less severe disease response (no corneal perforation) than wild-type B6 mice and had a significantly lower delayed-type hypersensitivity response to heat-killed pseudomonas Ag. These results support a critical role for B7/CD28 costimulation in susceptibility to P. aeruginosa ocular infection.

Epstein-Barr virus-associated B cell lymphoproliferative disorder following mismatched related T cell-depleted bone marrow transplantation.

Epstein-Barr virus (EBV) is closely associated with the progressive and often fatal lymphoproliferative disorders (LPD) in post bone marrow transplantation (BMT) and immunocompromised hosts. The incidence increases significantly when alternative donors or manipulation of marrow graft are used. A total of 318 consecutive BMT from partially mismatched related family donors (PMRD) were performed between February 1993 and June 1998. Known risk factors for the development of EBV-LPD were analyzed which included HLA mismatches, T cell depletion, antithymocyte globulin (ATG), and graft-versus-host disease (GVHD). Eighteen patients (5.7%) developed EBV-LPD at a median of 137 days post BMT (range 48-617). The estimated probability of developing EBV-LPD was 0.13 (95% CI 0.07-0.19) at 5 years. The incidence of grade II to IV GVHD was 19.2%, which translated into an increased trend of EBV-LPD. No correlation with other risk factors was observed. Treatment consisted of supportive antiviral agents, tapering of immunosuppressive regimens, donor leukocyte infusions and radiation. Three patients are alive and disease-free at a median follow-up of 69 months (range 36-71). We observed a lower than expected incidence of EBV-LPD despite existing multiple high-risk factors. We believe prevention and early control of GVHD may contribute to this finding.

Alkaline protease-deficient mutants of Pseudomonas aeruginosa are virulent in the eye.

PURPOSE: Alkaline protease has been associated with virulence in Pseudomonas aeruginosa corneal infections. To define the role of this enzyme in such infections, isogenic mutants of P. aeruginosa deficient in alkaline protease production were constructed. This study examines the ability of these mutants to adhere to scarified corneal tissue in vitro and to establish corneal infections in vivo. METHODS: Mutants were constructed by allelic exchange in two phenotypically different wild type strains, PAO1 (invasive) and ATCC 19660 (cytotoxic). Alkaline protease-deficient mutants were characterized by zymography and western blot analysis of bacterial culture supernatants. Allelic exchange was confirmed by PCR analysis of the disrupted aprA gene of the mutants. Adherence of wild type and mutant strains to scarified corneal epithelium was assessed by an in vitro organ culture assay, while ocular virulence of the strains was determined in vivo using a mouse scarification model of bacterial keratitis. RESULTS: Being isogenic, phenotypes of mutants were identical to their respective parents with the exception of the loss of alkaline protease production. The absence of alkaline protease did not alter corneal adherence or ocular virulence of the organisms when compared to similar wild type strains. CONCLUSIONS: These data provide evidence that alkaline protease produced by P. aeruginosa is not essential in the pathogenesis of P. aeruginosa keratitis.

C57BL/6 mice lacking Muc1 show no ocular surface phenotype.

PURPOSE: To test the hypothesis that a membrane-spanning mucin, Muc1, facilitates the spread of tear film and protects against bacterial adherence. METHODS: Age-matched, Muc1 null mice and wild-type mice of C57BL/6 genetic background were used for comparison. Eyes were examined by slit lamp biomicroscopy with fluorescein solution to assess epithelial damage and tear film stability. Structure of the ocular surface epithelia was examined by light microscopy, scanning and transmission electron microscopy, and wholemount confocal microscopy. Bacterial adherence assay was performed on in vivo corneas with Pseudomonas aeruginosa containing a plasmid encoding green fluorescent protein, followed by wholemount confocal microscopy. Real-time reverse transcription-polymerase chain reaction was performed using Muc4-specific primers to quantitate Muc4 mRNA expression in ocular surface tissues. RESULTS: No differences were found between Muc1 null and control mice in any parameter tested. Ocular surface epithelia of Muc1 null mice of the C57BL/6 strain had a normal appearance of surface microplicae, a well-developed glycocalyx on the apical cell membrane, and a normal appearance of goblet cell mucin packets. There was no convincing evidence that bacterial adherence on the cornea was increased in Muc1 null mice. Muc4 mRNA expression was not upregulated in Muc1 null mice compared with control. No ocular surface infections were observed in Muc1 null mice of the C57BL/6 strain (n = 204), which were housed in the animal facility over a period of 26 months. CONCLUSIONS: Muc1 null mice of C57BL/6 background appeared normal in all respects tested. These data differ from the reported phenotype in the mice of the C57BL/6 x SVJ129 background, which show development of blepharitis and conjunctivitis.

Aging and PMN response to P. aeruginosa infection.

PURPOSE: Alterations in immune system function associated with aging may contribute to increased morbidity in this population of individuals. The current studies were performed to determine aging-related changes in polymorphonuclear neutrophil (PMN) function after corneal infection with Pseudomonas aeruginosa. METHODS: Total PMN number, macrophage inflammatory protein (MIP)-2 mRNA and protein expression, and ocular bacterial load were determined in 8-week- and 12-month-old inbred BALB/c mice at various times after infection with P. aeruginosa. In addition, 12-month-old mice were treated systemically with the MIP-2 polyclonal antibody (pAb) to determine the effects of MIP-2 neutralization on ocular disease and PMN recruitment. RESULTS: Histologically, PMN infiltration into the cornea of 12-month-old mice was delayed initially and was associated with an inability to reduce bacterial load at later postinfection (PI) times. In addition, a significantly greater number of PMNs were found in the cornea of 12-month-old mice at later PI times. The increase in PMN number in 12-month-old mice correlated with a persistence of MIP-2 expression in cornea at these later times. Systemic treatment of 12-month-old mice with neutralizing MIP-2 pAb versus normal rabbit serum (NRS) resulted in reduced corneal PMN number and ocular disease. CONCLUSIONS: These data provide evidence that persistence of PMN in the cornea of 12-month-old mice contributes to corneal tissue destruction after P. aeruginosa challenge. Further evidence also is provided that the chemoattractant MIP-2 contributes to the altered PMN response in these animals.

Prolonged elevation of IL-1 in Pseudomonas aeruginosa ocular infection regulates macrophage-inflammatory protein-2 production, polymorphonuclear neutrophil persistence, and corneal perforation.

The kinetics of IL-1 (alpha and beta) production after Pseudomonas aeruginosa corneal infection was examined in susceptible (cornea perforates) C57BL/6J (B6) and resistant (cornea heals) BALB/cByJ (BALB/c) mice. IL-1alpha and -1beta (mRNA and protein) were elevated in both mouse strains, and levels peaked at 1 day postinfection (p.i. ). Significantly greater amounts of IL-1 protein were detected in B6 vs BALB/c mice at 1 and 3 days p.i. At 5 days p.i., IL-1alpha and -1beta (mRNA and protein) remained elevated in B6, but began to decline in BALB/c mice. To test the significance of elevated IL-1 in B6 mice, a polyclonal neutralizing Ab against IL-1beta was used to treat infected B6 mice. A combination of subconjunctival and i.p. administration of IL-1beta polyclonal Ab significantly reduced corneal disease. The reduction in disease severity in infected B6 mice was accompanied by a reduction in corneal polymorphonuclear neutrophil number, bacterial load, and macrophage inflammatory protein-2 mRNA and protein levels. These data provide evidence that IL-1 is an important contributor to P. aeruginosa corneal infection. At least one mechanism by which prolonged and/or elevated IL-1 expression contributes to irreversible corneal tissue destruction appears to be by increasing macrophage inflammatory protein-2 production, resulting in a prolonged stimulation of polymorphonuclear neutrophil influx into cornea. In contrast, a timely down-regulation of IL-1 appears consistent with an inflammatory response that is sufficient to clear the bacterial infection with less corneal damage.

Design and estimation in the limiting dilution assay when concentrations vary widely among samples.

Limiting dilution assays (LDA) are used to estimate an unknown cell fraction of interest within a sample. This paper discusses a method for designing an LDA using the distribution of the cell fraction of interest, examining three different design approaches: geometric progression, equally spaced log, and equiprobability. Two common estimation methods, minimum chi-square and maximum likelihood, also are investigated. These designs and estimation methods, coupled with varying numbers of wells per dilution and dilutions per design, are compared quantitatively through computer simulation. Performance measures computed were mean relative bias and mean squared error.

Perlecan in the basement membrane of corneal epithelium serves as a site for P. aeruginosa binding.

PURPOSE: To determine whether binding of Pseudomonas aeruginosa (P. aeruginosa) to the scarified mouse cornea depends on interaction with proteoglycans (PGs). METHODS: Scarified corneas were treated with anti-proteoglycan monoclonal antibodies (MAbs), glycosaminoglycans (GAGs), heparinase III or chondroitin ABC lyase before inoculation with P. aeruginosa strain ATCC 19660 or PAO1. Scanning electron microscopy (SEM) was used to quantitate adherent bacteria. Frozen sections of unwounded and wounded mouse cornea, the latter treated or not treated with heparinase III were stained to spatially localize perlecan [core protein or heparan sulfate (HS) side chains]. Anti-perlecan MAb against the heparan sulfate proteoglycan core protein and succinyl wheat germ agglutinin (sWGA), a lectin which recognizes N-acetyl-glucosamine in heparan sulfate, respectively were used. RESULTS: Anti-perlecan MAb, as well as heparan sulfate, heparin and heparinase III decreased the binding of both bacterial strains to cornea, and the decrease was concentration-dependent. Fluorescence microscopic analysis of sections of mouse cornea immunostained with anti-perlecan MAb showed that perlecan was localized to the epithelial basement membrane. Scarification of the mouse cornea exposed perlecan in the basement membrane and increased bacterial binding to this site was consistent with this exposure. Lectin staining revealed that heparinase treatment removed heparan sulfate side chains of perlecan from the exposed basement membrane, and this removal was consistent with a decrease in bacterial binding. CONCLUSIONS: These studies provide evidence that perlecan, core protein and its heparan sulfate side chains serve as a binding site for Pseudomonas aeruginosa when the basement membrane of the cornea is exposed.

Partially mismatched related-donor bone marrow transplantation for pediatric patients with acute leukemia: younger donors and absence of peripheral blasts improve outcome.

PURPOSE: To extend access to bone marrow transplantation (BMT), we used partially mismatched related donors (PMRD) for pediatric patients with acute leukemia. In this report we sought to determine pretransplantation factors that might predict outcome. PATIENTS AND METHODS: Of 67 such patients, 43 had acute lymphocytic leukemia and 24 had acute myelogenous leukemia. At the time of transplantation, 41 patients were in relapse. Donors included 40 parents, 24 siblings, and three cousins. HLA disparity of two to three major antigens was detected in two thirds of the donor-recipient pairs. Conditioning therapy, including total-body irradiation and chemotherapy followed by graft-versus-host disease (GvHD) prophylaxis with partial T-cell depletion of the graft using T10B9 or OKT3, was combined with posttransplantation immunosuppression. RESULTS: Estimated probability (EP) of engraftment was 0.96 and was not affected by donor-antigen mismatch (AgMM; P =.732). EP of grades 2 to 4 acute GvHD was 0.24 and was not affected by recipient AgMM (P =.796). EP of disease-free survival was 0.26 at 3 years but improved to 0.45 when donors were younger than 30 years (P<.001). EP of relapse at 3 years was 0.41 and reduced with younger donors' age. For patients who were in relapse at the time of transplantation, absence of blasts was associated with a lower relapse rate (0.46 v. 0.84; P =. 083), similar to that of patients in remission. CONCLUSION: PMRD-BMT in pediatric leukemia resulted in high engraftment and low GvHD rates. To improve outcomes, younger donors should be sought, and clinicians should attempt to reduce peripheral blasts in patients who are in relapse.

Increased severity of Pseudomonas aeruginosa corneal infection in strains of mice designated as Th1 versus Th2 responsive.

PURPOSE: Mice favoring Th1 (C57BL/6, C57BL/10, and B10.D2/nSn) versus Th2 (BALB/c, BALB/cBy, BALB.B, and BALB.K) response development were evaluated for their response to infection with Pseudomonas aeruginosa. This study addresses the question of whether Th1 versus Th2 response propensity affects the pathogenesis of bacterial keratitis in mice. METHODS: Ocular disease was determined by mean clinical score, slit lamp, plate counts, and histopathology, and antigen-specific cellular responses were assessed by immunostaining and measurement of delayed type hypersensitivity (DTH). RESULTS: Strains of mice favoring Th1 (B6, BL10, and B10.D2) versus Th2 (BALB/c, BALB/cBy, BALB.B, and BALB.K) responsiveness were infected with P. aeruginosa. Mice favoring Th1 response development exhibited a similar course of disease and the infected eyes of all mice perforated by 7 days postinfection (p.i.). Strains (BALB/c, BALB/cBy, BALB.B, and BALB.K) favoring Th2 response development exhibited a milder course of disease, and none of the infected corneas perforated at 7 days p.i. In a Th1-responsive strain (B10.D2), positive immunostaining for CD4+ and CD8+ T cells was observed in the cornea by 3 days p.i. and by 5 days p.i., respectively, some cells stained positively for IL2-R, indicating that the cells were activated. In contrast, in a Th2 responder strain (BALB/c), there was no detectable positive immunostaining in cornea for any of the T-cell markers tested and DTH was significantly elevated in B10.D2 versus BALB/c mice. CONCLUSIONS: These studies are the first to provide evidence that in P. aeruginosa ocular infection, mouse strains favoring development of a Th1-type response are susceptible (cornea perforates), whereas strains favoring Th2 response development are resistant (no corneal perforation).

Macrophage inflammatory protein-2 is a mediator of polymorphonuclear neutrophil influx in ocular bacterial infection.

Polymorphonuclear neutrophils (PMN) in Pseudomonas aeruginosa-infected cornea are required to clear bacteria from affected tissue, yet their persistence may contribute to irreversible tissue destruction. This study examined the role of C-X-C chemokines in PMN infiltration into P. aeruginosa-infected cornea and the contribution of these mediators to disease pathology. After P. aeruginosa challenge, corneal PMN number and macrophage inflammatory protein-2 (MIP-2) and KC levels were compared in mice that are susceptible (cornea perforates) or resistant (cornea heals) to P. aeruginosa infection. While corneal PMN myeloperoxidase activity (indicator of PMN number) was similar in both groups of mice at 1 and 3 days postinfection, by 5-7 days postinfection corneas of susceptible mice contained a significantly greater number of inflammatory cells. Corneal MIP-2, but not KC, levels correlated with persistence of PMN in the cornea of susceptible mice. To test the biological relevance of these data, resistant mice were treated systemically with rMIP-2. This treatment resulted in increased corneal PMN number and significantly exacerbated corneal disease. Conversely, administration of neutralizing MIP-2 pAb to susceptible mice reduced both PMN infiltration and corneal destruction. Collectively, these findings support an important role for MIP-2 in recruitment of PMN to P. aeruginosa-infected cornea. These data also strongly suggest that a timely down-regulation of the host inflammatory response is critical for resolution of infection.