Characterization of oral immune cells in birch pollen-allergic patients: impact of the oral allergy syndrome and sublingual allergen immunotherapy on antigen-presenting cells

BACKGROUND

A detailed characterization of human oral immune cells is needed to better understand local mechanisms associated with allergen capture following oral exposure.

METHODS

Oral immune cells were characterized by immunohistology and immunofluorescence in biopsies obtained from three healthy individuals and 23 birch pollen-allergic patients with/without oral allergy syndrome (OAS), at baseline and after 5 months of sublingual allergen immunotherapy (AIT).

RESULTS

Similar cell subsets (i.e., dendritic cells, mast cells, and T lymphocytes) were detected in oral tissues from healthy and birch pollen-allergic individuals. CD207+ Langerhans cells (LCs) and CD11c+ myeloid dendritic cells (DCs) were found in both the epithelium and the papillary layer of the Lamina propria (LP), whereas CD68+ macrophages, CD117+ mast cells, and CD4+ /CD8+ T cells were rather located in both the papillary and reticular layers of the LP. Patterns of oral immune cells were identical in patients with/without OAS, except lower numbers of CD207+ LCs found in oral tissues from patients with OAS, when compared to OAS- patients (P < 0.05). A 5-month sublingual AIT had a limited impact on oral immune cells, with only a significant increase in IgE+ cells in patients from the active group. Colocalization experiments confirmed that such IgE-expressing cells mostly encompass CD68+ macrophages located in the LP, and to a lesser extent CD207+ LCs in the epithelium.

CONCLUSION

Two cell subsets contribute to antigen/allergen uptake in human oral tissues, including (i) CD207+ LCs possibly involved in the physiopathology of OAS and (ii) CD68+ macrophages likely critical in allergen capture via IgE-facilitated mechanisms during sublingual AIT.

Thermal damage assessment of blood vessels in a hamster skin flap model by fluorescence measurement of a liposome-dye system

BACKGROUND AND OBJECTIVES

The present study was undertaken to evaluate the feasibility of thermal damage assessment of blood vessels by using laser-induced release of liposome-encapsulated dye.

STUDY DESIGN/MATERIALS AND METHODS

Experiments were performed in a hamster skin flap model. Laser irradiation was achieved with a 300 microm fiber connected to a 805 nm diode laser (power = 0.8W, spot diameter = 1.3 mm and pulse exposure time lasting from 1 to 6 s) after potentiation using a specific indocyanine green (ICG) formulation (water and oil emulsion). Liposomes-encapsulated carboxyfluorescein were prepared by the sonication procedure. Carboxyfluorescein (5,6-CF) was loaded at high concentration (100 mM) in order to quench its fluorescence. The measurements were performed after i.v. injection of DSPC liposomes (1.5 ml) and lasted 40 min. Fluorescence emission was measured with an ultra high sensitivity intensified camera.

RESULTS

Three different shapes of fluorescent spots were identified depending on target (blood vessel or skin) and energy deposition in tissue: (i) intravascular fluorescence, (ii) transient low fluorescence circular spot, and (iii) persistent high intense fluorescence spot. These images are correlated with histological data.

CONCLUSION

Real-time fluorescence imaging seems to be a good tool to estimate in a non-invasive manner the thermal damage induced by a diode laser combined with ICG potentiation.

[Control of photocoagulation intensity by thermo-induced release of a fluorescent marker encapsulated in liposomes: study of an in vivo vascular model]

PURPOSE

To evaluate the feasibility of thermal damage assessment of blood vessels by using laser-induced release of liposome-encapsulated dye.

METHODS

A skin flap window model of aluminium was implanted on the loose skin on the back of adults Golden hamsters to expose skin blood vessels in vivo. Thermosensitive liposomes (DSPC) loaded with 5,6-Carboxyfluorescein were injected together with a specific Indocyanine green (ICG) formulation (O/W emulsion) in order to enhance diode laser absorption. Photocoagulations were then performed on the vessels with a diode laser (lambda = 810 nm, P = 0.8W, phi = 1.3 mm, 1 to 6s). Fluorescence measurements were realized with an ultra high sensitivity intensified camera (Hamamatsu Argus 50 imaging system).

RESULTS

Two different fluorescence intensity curves corresponding to the variability of absorption of the targets were observed. Variability was related to the amount of ICG. For each curve, 3 zones were identified: (i) for fluences ranging from 60 +/- 20 J/cm2 to 110 +/- 20 J/cm2 a transient intravascular fluorescence was observed only for the loser pulses targeted on the vessels, (ii) for fluences ranging from 110 +/- 20 J/cm2 to 190 +/- 20 J/cm2 a permanent fluorescent spot limited to the vessel was observed for the laser pulses targeted on the vessels; for the laser pulses targeted on the skin a transient low fluorescence circular spot was observed. For this fluence range a selective photocoagulation of a vessel was performed. (iii) for fluences ranging from 190 +/- 20 J/cm2 to 300 +/- 20 J/cm2 persistent intense fluorescence spots were observed on both skin and vessels. This type of fluorescence was related to an overdosage.

CONCLUSION

These results are in fair agreement with the data of the literature about liposomes and with the data we obtained in a previous study on a vascular model. This study demonstrates the interest of a laser-induced release of liposome-encapsulated dye for a real-time quantification of thermal damage. Such a method could be useful for laser photocoagulation in ophthalmology for indications such as choroidal neovessels where the production of a precise thermal damage is required.

Fluorescence measurement of 805 nm laser-induced release of 5,6-CF from DSPC liposomes for real-time monitoring of temperature: an in vivo study in rat liver using indocyanine green potentiation

BACKGROUND AND OBJECTIVE

This in vivo study examines the validity of using fluorescence measurements of laser-induced release of temperature-sensitive, liposome-encapsulated dye for real-time monitoring of temperature and for prediction of tissue thermal damage.

STUDY DESIGN/MATERIALS AND METHODS

An in vivo study is performed in rat liver after i.v. injection of liposomes loaded with a fluorescent dye and i.v. injection of indocyanine green (ICG) for diode laser potentiation. Temperature-sensitive liposomes (DSPC: Di-Stearoyl-Phosphatidyl-Choline) are loaded with 5,6-carboxyfluorescein (5,6-CF). These liposomes (1.5 ml solution) and ICG (1.5 ml solution-5mg/kg) are injected in adult male wistar rats. Two hours later, the liver is exposed and irradiated with a 0.8 W diode laser using pulses lasting from 1-6s (fluence ranging from 16-98 J/cm2). Simultaneously, the fluorescence emission is analysed with an ultrahigh sensitivity intensified camera.

RESULTS

The fluorescence intensity I(F) increases linearly from 18 J/cm2 up to 75 J/cm2. These fluences correspond to surface temperatures between 42 degrees C and 65 degrees C. The measurements appear to be highly reproducible. In this temperature range, the accuracy is +/- 3 degrees C. The maximum intensity is observed immediately after the laser is switched off. A decrease of the fluorescence intensity (27% in 20 minutes) is observed due to the 5,6-CF clearance. However, the ratio I(F)/I(BCK) (I(BCK): background fluorescence intensity) remains almost stable over this period of time and the determination of the temperature is still possible with good accuracy even 20 minutes after laser irradiation.

CONCLUSION

Real-time temperature monitoring by using fluorescence measurement of laser-induced release of liposome-encapsulated dye is clearly demonstrated. This procedure could conceivably prove useful for controlling the thermal coagulation of biological tissues.