Christine M. Rapp

THE DEVELOPMENT OF PROTECTIVE IMMUNITY IN CANINE SCABIES

Seven of eight dogs that had been previously infested with Sarcoptes scabiei var. canis and then cured, expressed protective immunity when experimentally reinfested with scabies. All seven dogs that expressed resistance were spontaneously cleared of scabies by 64 days after they were experimentally reinfested. Five of the eight dogs were free of scabies by 24 days. The sequential changes in the inflammatory/immune cellular infiltrate in the scabietic lesions of each dog were determined during the sensitizing infestation, cure and the subsequent experimental reinfestation (challenge). During the initial infestation and in the subsequent challenge reinfestation, dogs developed mixed cellular infiltrates in their scabietic lesions that contained mononuclear cells, neutrophils, plasma cells and mast cells. Reinfestation induced more rapid increases in the densities of these cells than had occurred during the sensitizing infestation. Mononuclear and mast cells were the most numerous infiltrating cells during the sensitizing phase. During the challenge phase the most numerous infiltrating cells were mononuclear cells and neutrophils. The sensitizing and challenge infestations induced circulating scabies-specific antibody responses, but the response was more rapid during the reinfestation challenge. Both the cell-mediated response in the skin and the circulating antibody response waned in parallel with clearing of the mites following reinfestation.

Production of IL-1 alpha and IL-1 beta by human skin equivalents parasitized by Sarcoptes scabiei.

Human skin equivalents (HSEs) were used as a model to investigate interleukin (IL)-1 alpha and IL-1 beta secretions by keratinocytes stimulated by Sarcoptes scabiei (SS). SS mites burrowed into the stratum corneum when placed on the surface of cultured HSEs. Mites lived for 14 days. Mites and mite products induced cells in the HSEs to secrete IL-1 alpha and IL-1 beta within 16 hr. Scabies mites induced production of greater amounts of IL-1 alpha than IL-1 beta. Hepatocyte growth factor in the culture medium at 3 and 30 ng/ml upregulated the secretions of both IL-1 alpha and IL-1 beta by mite-infested skin equivalents, whereas 10 ng/ml of IL-6 upregulated production of only IL-1 beta. Therefore, these cytokines were important immunomodulating factors influencing keratinocyte secretion of IL-1 alpha and IL-1 beta in vitro. The results of this study provide the first evidence that keratinocytes (possibly fibroblasts) in the skin produce these cytokines in response to scabies mites or other ectoparasitic arthropods. Because IL-1 alpha and IL-1 beta are potent inducers of inflammation and keratinocytes are among the first effector cells to encounter scabies mites and their products, these cells may be key initiators of the inflammatory/immune reaction to scabies.

Allergenicity of Euroglyphus maynei and its cross-reactivity with Dermatophagoides species

BACKGROUND The house dust mite, Euroglyphus maynei (EM), is common in homes in England, Europe, the southern United States, and other parts of the world. It is often present in densities greater than 100 mites per gram of dust. EM usually occurs with Dermatophagoides farinae (DF) and D. pteronyssinus (DP) and it is frequently more abundant than Dermatophagoides species. Therefore the allergenicity of EM and the cross-reactivity between EM and Dermatophagoides species are important considerations for diagnosis of mite-induced allergy and the use of appropriate immunotherapy. METHODS Crossed immunoelectrophoresis revealed that EM was the source of at least 33 antigens. Crossed radioimmunoelectrophoresis with 32 different sera from patients with RAST results that were positive to EM and skin test results that were positive to both DF and DP identified 15 allergens. Individual sera recognized two to eight EM antigens as allergens. RESULTS Ninety-one percent of the patients showed serum IgE directed at three or more allergens. Eighty-four percent of the patients had moderate or strong levels of IgE directed at antigen no. 33. All 15 allergens showed moderate or strong IgE binding by one or more sera. EM shared four and six cross-reacting allergens with DF and DP, respectively. Therefore 11 and 9 allergens of EM were species-specific and not shared by DF and DP, respectively. CONCLUSIONS The results of this study clearly indicate that sensitivity to EM should be considered in geographic areas where this mite is abundant in homes.

Presence of Host Immunoglobulin in the Gut of Sarcoptes scabiei (Acari: Sarcoptidae)

Abstract Sarcoptes scabiei (De Geer) mites burrow in the nonliving stratum corneum of the epidermis of their mammalian hosts. These mites ingest extracellular fluid (serum) that seeps into the burrow from the lower vascular dermis. A strong host antibody response occurs when mites die in the skin. This suggests internal immunogenic proteins are released into the host at this time. Vaccination with internal antigens may be an approach to protect against this mite if host antibody to internal antigens that regulate key physiological processes is ingested along with serum. Our study clearly showed that scabies mites ingest host immunoglobulin as evidenced by the localization of fluorescent-labeled antibody to host immunoglobulin in the anterior midgut and esophagus of fresh mites removed from the host. This is the first study that demonstrates that this nonblood-feeding ectoparasitic mite ingests host antibody while feeding on tissue fluid that seeps into the stratum corneum.

Distribution and removal of cat, dog and mite allergens on smooth surfaces in homes with and without pets

BACKGROUND Removing allergen from the indoor environment should be a primary strategy for the management and treatment of allergic disease. OBJECTIVE The aims of this study were to characterize the distribution of dog, cat, and mite allergen on hard surfaces in homes with and without pets and to evaluate the efficiency of removing allergen from hard surfaces by wiping with a dry dust cloth and by vacuum cleaning using the dustbrush attachment. METHODS The amount of allergen collected from adjacent areas of two smooth floors, a wall, and finished furniture by wiping with a Pledge Grab-it dust cloth (S. C. Johnson & Son, Inc, Racine, WI) and by brush-vacuuming were compared for 24 homes with and without pets. In addition, the areas first wiped with the dust cloth were then brush-vacuumed and the amounts of allergen collected by the first and second cleaning were compared. RESULTS A key finding was that 23 of the 24 homes had Can f 1 allergen on one or more of the sampled areas regardless of whether a dog was present. Most homes with pets and many homes without pets had Can f 1 and Fel d 1 allergens on walls, smooth floors, and finished furniture. Carpets were the major reservoir for pet allergens in homes with pets whereas allergen was more uniformly distributed in homes without pets. Little mite allergen was found on hard surfaces even when it was present in carpets. CONCLUSIONS Dog and cat allergens are prevalent on walls, smooth floors, and finished furniture in homes with and without pets. Dry dusting with a Grab-it dust cloth was an effective cleaning method for removing allergen from hard smooth surfaces.

Characterization of lymphocyte subtypes in scabietic skin lesions of naive and sensitized dogs

We delineated the density of cells expressing CD4, CD8, CD21 and CD45RA antigens in the cellular infiltrates in the epidermis, dermis and follicular epithelium in scabietic skin lesions of naive hosts and sensitized hosts that expressed resistance to scabies infestation. No cells expressing CD21 (B-lymphocytes and follicular dendritic cells) were present in the epidermis and only a few were occasionally present in the dermis during both the first and second infestations. Naive T-cells (CD45RA+) and CD8+ cells (cytotoxic and suppressor T-lymphocytes) were present in varying densities in the infiltrates throughout the epidermis, dermis and follicular epithelium with no apparent differences in density and the rate of appearance between sensitizing and challenge infestations. CD4+ cells were abundant in fluctuating densities in the dermis, epidermis, and follicular epidermis during the sensitizing infestation and these cells became the dominant cell type early during the challenge infestation. The density of CD4+ cells in the infiltrate was much greater during the challenge than during the sensitization infestation. This population of CD4+ cells consisted of both T-helper/inducer cells and neutrophils and the large increase in their numbers during the challenge suggested they played a key role in the successful immune/inflammatory response that resulted in resistance to scabies infestation.

SOME EFFECTS OF SARCOPTIC MANGE ON DOGS

Sequential changes in pathology were examined for scabies-infested dogs to determine the effects of infestation with Sarcoptes scabiei var. canis. During 8 wk of infestation with S. scabiei, the progression of the disease was evaluated weekly by skin scrape, clinical examination, and blood analyses. At 8 wk, selected organs were microscopically examined for histopathology. All infested dogs developed an advanced level of scabies infestation by 8 wk. Of the 36 blood parameters evaluated, only values for erythrocyte sedimentation rate (ESR) deviated significantly from the normal ranges for dogs. However, infested dogs had significantly (P < 0.01) lower average hemoglobin and hematocrit concentrations after 8 wk of infestation compared to their values prior to infestation or to the values for the control dogs. Red blood cell levels for infested dogs dropped significantly (P < 0.01) from preinfestation concentrations by week 8. Conversely, by 8 wk total white blood cell and neutrophil concentrations were significantly (P < 0.01) greater than uninfested controls. Also, whereas average eosinophil concentrations were not statistically different for infested dogs compared to controls, some individual infested dogs exhibited eosinophilia at 4-8 wk of infestation. The ESRs for infested dogs were significantly (P < 0.01) greater at week 6 and 8 than for experimental dogs prior to infestation or control dogs. All parameters except neutrophils had returned to preinfestation levels by 2 wk after treatment for scabies. Neutrophil concentrations were no longer significantly different by 4 wk posttreatment. There were no significant differences in serum enzyme, biochemical and electrolyte concentrations between infested and control dogs.(ABSTRACT TRUNCATED AT 250 WORDS)

A murine model for sarin exposure using the carboxylesterase inhibitor CBDP.

Sub-lethal exposure to sarin (GB), a potent chemical warfare agent, produces long-term neurological deficits in both humans and rodents. However, rodents express much higher levels of carboxylesterase (CaE) than humans and require a much higher dose of GB in rodents to produce neurotoxicity. In mice, the combination of the carboxylesterase inhibitor 2-(o-cresyl)-4H-1:3:2-benzodioxaphosphorin-2-oxide (CBDP) with the organophosphorus (OP) nerve agent GB renders mice more sensitive to OP poisoning. After the reduction in CaE, GB inhibits acetylcholinesterase at doses similar to those in human toxicity. A dose-response curve for GB was determined in male C57BL/6 mice after 1.5mg/kg CBDP. A functional observational battery (FOB) for behavior was used to determine the dose needed to elicit seizure activity but maintain a mortality of less than 50%. Neuronal cell death was evaluated at 4, 7, 10 and 14 days post-GB exposure. Multiple brain areas were examined using cresyl violet: CA1 and the dentate gyrus of the hippocampus, amygdala and piriform cortex. GFAP staining was then measured as an index of cell death in the dentate gyrus of the hippocampus. The dentate gyrus and CA1 exhibited significant neuronal death indicated by both cresyl violet and GFAP staining. The treated animals also had a significant decrease in tissue and blood acetylcholinesterase, in addition to decreases in plasma CaE. CBDP renders mice more sensitive to the effects of GB exposure and mirrors a human symptomatic exposure dose.

Light Induced and Circadian Effects on Retinal Photoreceptor Cell Crystallins

Crystallins in the retina may serve a chaperone‐like protective function. In this study we measured mRNA levels for alpha‐, beta‐ and gamma‐crystallins in rat retinas following treatment with potentially damaging levels of light. We also determined crystallin protein patterns in photoreceptor cell rod outer segments (ROSs) isolated from rats exposed to intense light. Weanling albino rats were maintained in a dim cyclic light environment or in darkness for 40 days. At P60 animals were treated with intense visible light, for as long as 8 h, beginning at various times of the day or night. Retinas were excised immediately after light treatment and used for quantitative RT‐PCR, or to prepare ROSs for western analysis. Some eyes were frozen in OCT for crystallin immunohistochemistry. Intense light exposure led to increases in mRNA expression for all retinal crystallins and to changes in ROS crystallin immunoreactivity. These light‐induced changes were found to depend on the time of day that exposure started, duration of light treatment and previous light rearing history. We suggest that crystallin synthesis in retina exhibits a dependence on both light stress and circadian rhythm and that within photoreceptor cells crystallins appear to migrate in a light‐independent, circadian fashion.

Light-Induced Retinal Degeneration Is Prevented by Zinc, a Component in the Age-related Eye Disease Study Formulation †

Mineral supplements are often included in multivitamin preparations because of their beneficial effects on metabolism. In this study, we used an animal model of light‐induced retinal degeneration to test for photoreceptor cell protection by the essential trace element zinc. Rats were treated with various doses of zinc oxide and then exposed to intense visible light for as long as 8 h. Zinc treatment effectively prevented retinal light damage as determined by rhodopsin and retinal DNA recovery, histology and electrophoretic analysis of DNA damage and oxidized retinal proteins. Zinc oxide was particularly effective when given before light exposure and at doses two‐ to four‐fold higher than recommended by the age‐related eye disease study group. Treated rats exhibited higher serum and retinal pigment epithelial zinc levels and an altered retinal gene expression profile. Using an Ingenuity database, 512 genes with known functional annotations were found to be responsive to zinc supplementation, with 45% of these falling into a network related to cellular growth, proliferation, cell cycle and death. Although these data suggest an integrated and extensive regulatory response, zinc induced changes in gene expression also appear to enhance antioxidative capacity in retina and reduce oxidative damage arising from intense light exposure.