Pre-exposure with low-dose UVA suppresses lesion development and enhances Th1 response in BALB/c mice infected with Leishmania (Leishmania) amazonensis

UVA-Degradable Collagenase Nanocapsules as a Potential Treatment for Fibrotic Diseases

Peyronie and Dupuytren are pathologies characterized by the appearance of localized fibrotic lesions in an organ. These disorders originate from an excessive production of collagen in the tissue provoking dysfunction and functional limitations to the patients. Local administration of collagenase is the most used treatment for these fibrotic-type diseases, but a high lability of the enzyme limits its therapeutic efficacy. Herein, we present a novel methodology for the preparation of collagenase nanocapsules without affecting its enzymatic activity and capable of releasing the enzyme in response to an ultraviolet A (UVA) light stimulus. Polymeric coating around collagenase was formed by free-radical polymerization of acrylamide-type monomers. Their degradation capacity under UVA irradiation was provided by incorporating a novel photocleavable acrylamide-type crosslinker within the polymeric framework. This property allowed collagenase release to be triggered in a controlled manner by employing an easily focused stimulus. Additionally, UVA irradiation presents considerable benefits by itself due to its capacity to induce collagenase production in situ. An expected synergistic effect of collagenase nanocapsules in conjunction with UVA effect may present a promising treatment for these fibrotic diseases.

Immunosuppressive ultraviolet-A radiation inhibits the development of skin memory CD8 T cells

Ultraviolet A (UVA) radiation can have dual affects on the immune system depending on dose. At doses of approximately 1.8 J cm(-2), UVA acts in an immunosuppressive manner, whilst at higher doses UVA can promote recovery and protection against UVB-induced immunosuppression in mice. We utilised a model of contact hypersensitivity (CHS) to investigate how different doses of UVA modulates CD8 T cell immunity against a hapten in vivo. Only 1.8 J cm(-2) UVA decreased the CHS response compared to unirradiated mice, but this did not correlate with an inhibition of primary effector CD8 T cells. A similar expansion of effector CD8 T cells in skin-draining lymph nodes and accumulation of IFN-gamma-producing CD8 T cells in the ear skin was observed between unirradiated and UVA-irradiated mice. However, dermal memory CD8 T cells examined 9 weeks post challenge showed decreased numbers in mice irradiated with 1.8 J cm(-2) UVA compared with unirradiated, 1.3 J cm(-2) and 3.4 J cm(-2) UVA-irradiated mice. Therefore, UVA does not inhibit the expansion, migration or IFN-gamma secretion of CD8 T cells during a primary immune response. However, exposure to immunosuppressive UVA causes a defect in CD8 T cell development that impairs the ability of cells to become long-term memory cells.

Hyperbaric oxygen therapy reduces the size of Leishmania amazonensis-induced soft tissue lesions in mice

In this study we determined whether exposing mice to hyperbaric oxygen (HBO) would alter various disease parameters of a susceptible mouse strain infected with Leishmania amazonensis. BALB/c mice exposed to HBO (100% O2 at a pressure of 2.5 ATA, 1h before parasite inoculation and subsequently for 20 days) showed significant delay in lesion development and reduction in lesion parasite burdens compared with HBO-unexposed mice. Circulating levels of interferon gamma (IFN-gamma) and tumor necrosis factor (TNF-alpha) were significantly elevated in HBO-exposed as compared to HBO-unexposed mice. Concanavalin A-stimulated lymph nodes cultures from HBO-exposed mice released significantly more IFN-gamma and less interleukin 10 (IL-10) than cultures from HBO-unexposed mice, consistent with a skewed Th1 response. These results demonstrate, for the first time, that HBO can play a pathogen control role during leishmaniasis. Further studies are needed to elucidate whether hyperoxia alone or increased atmospheric pressure alone can exert a similar effect.

Photoimmunoprotection by UVA (320-400 nm) radiation is determined by UVA dose and is associated with cutaneous cyclic guanosine monophosphate

The immunomodulating properties of UVA radiation remain controversial. Here, we demonstrate in female inbred Skh:hr-1 mice that single subinflammatory UVA exposures between 1.61 and 580.5 kJ/m(2) are not immunosuppressive. Furthermore, UVA exposures between 16.13 and 580.5 kJ/m(2) provided dose-related immunoprotection against UVB-induced immunosuppression. Higher UVA exposures (870.8-1,161 kJ/m(2)) became inflammatory and immunosuppressive alone, and lost the photoimmunoprotective capacity. We previously reported that UVA photoimmunoprotection depends on the induction of cutaneous heme oxygenase-1, particularly its enzymatic product, carbon monoxide (CO). CO was suggested to activate cutaneous guanylyl cyclase (GC), as the specific GC inhibitor, 1H-(1,2,4)oxadiazolo-(4,3-a)quinoxalin-1-one (ODQ), abrogated CO photoimmunoprotection in the mouse. This study shows that cutaneous cyclic guanosine monophosphate (cGMP) concentration increased only following immunoprotective UVA doses, or immunoprotective topical CO treatment, and cGMP production was inhibited by ODQ. Conversely, cGMP concentration was increased by inhibition of its degradative phosphodiesterase (PDE) with topical sildenafil. The PDE-5 isoform was identified in normal mouse skin. Subsequently, a moderate concentration of sildenafil was shown to simulate the effect of UVA in protecting against photoimmunosuppression by solar-simulated UV radiation or its mediator cis-urocanic acid. Thus, cutaneous cGMP, controlled by its synthesis via CO-activated GC and its degradation by PDE-5, is strongly associated with UVA photoimmunoprotection.

Repeated irradiations with gamma-rays at a Dose of 0.5 Gy may exacerbate asthma

We previously showed that 0.5 Gy whole-body gamma-ray irradiation with a single or small number of repeated exposures inhibits tumor growth in mice, via elevation of the IFN-gamma/IL-4 ratio concomitantly with a decrease in the percentage of B cells. Here we examined whether repeated 0.5 Gy gamma-rays irradiation can improve asthma in an OVA-induced asthmatic mouse model. We found that repeated irradiation (10 times) with 0.5 Gy of gamma-rays significantly increased total IgE in comparison with the disease-control group. The levels of IL-4 and IL-5 were also significantly higher in the gamma-ray-irradiated group, while that of IFN-gamma was significantly lower, resulting in a further decrease of the IFN-gamma/IL-4 ratio from the normal value. These results indicate that the repeated irradiation with gamma-rays may exacerbate asthma, and may have opposite effects on different immune reactions unlike the irradiation with a single or small number of repeated exposures.

Ultraviolet A (320–400 nm) Modulation of Ultraviolet B (290–320 nm)-Induced Immune Suppression Is Mediated by Carbon Monoxide

Accumulating evidence suggests that suberythemogenic ultraviolet A (UVA) (320-400 nm) exposure protects against the immunosuppressive effect of ultraviolet B (290-320 nm) radiation or its epidermal photoproduct, cis-urocanic acid (cis-UCA). In skin, UVA photoimmunoprotection is mediated by the inducible antioxidant stress enzyme, heme oxygenase-1 (HO-1), which degrades heme into carbon monoxide (CO), iron, and biliverdin (reduced to bilirubin), and is important for cell survival under conditions of oxidative stress. The identity of the HO enzymatic product(s) that provide the immunoprotection is unknown. Here we examine the potential of CO to fulfill this role in hairless mouse skin, utilizing a novel CO-releasing molecule (CO-RM) to deliver CO to the skin topically. The CO-RM released CO gradually from the lotion vehicle during 3 h following its preparation, and between 50 and 500 microM, concentration-dependently protected mice against the suppression of contact hypersensitivity by either solar-simulated UV radiation (SSUVR) or cis-UCA, whereas aged CO-depleted CO-RM was inactive. Thus, the CO-RM treatment mimicked UVA-photoimmunoprotection, and identified HO-released CO as the protective mediator, providing evidence that the murine cutaneous immune system is modulated by this gaseous messenger. Preliminary evidence for involvement of guanylyl cyclase was obtained by treatment of the mouse with its specific inhibitor 1H-(1,2,4)oxadiazolo-(4,3-1)quinoxaline-1-one, which abrogated UVA photoimmunoprotection.

Identification and molecular characterization of a gene encoding a protective Leishmania amazonensis Trp-Asp (WD) protein

Several Leishmania proteins have been identified and characterized in pursuit of understanding pathogenesis and protection in cutaneous leishmaniasis. In the present study, we utilized sera from infected BALB/c mice to screen a Leishmania amazonensis amastigote cDNA expression library and obtained the full-length gene that encodes a novel Trp-Asp (WD) protein designated LAWD (for Leishmania antigenic WD protein). The WD family of proteins mediates protein-protein interactions and coordinates the formation of protein complexes. The single-copy LAWD gene is transcribed as a approximately 3.1-kb mRNA in both promastigotes and amastigotes, with homologues being detected in several other Leishmania species. Immunoelectron microscopy revealed a predominant localization of the LAWD protein in the flagellar pocket. Analyses of sera from human patients with cutaneous and mucocutaneous leishmaniasis indicated that these individuals mounted significant humoral responses against LAWD. Given that recombinant LAWD protein elicited the production of high levels of gamma interferon, but no detectable levels of interleukin-10 (IL-10), in CD4(+) cells of L. amazonensis-infected mice, we further examined whether LAWD could elicit protective immunity. DNA vaccination with the LAWD and IL-12 genes significantly delayed lesion development, which correlated with a dramatic reduction in parasite burdens. Thus, we have successfully identified a promising vaccine candidate and antigenic vehicle to aid in the dissection of the complicated pathogenic immune response of L. amazonensis.

DNA immunization with the gene encoding P4 nuclease of Leishmania amazonensis protects mice against cutaneous Leishmaniasis

Infection with the protozoan parasite Leishmania amazonensis can cause diverse clinical forms of leishmaniasis. Immunization with purified P4 nuclease protein has been shown to elicit a protective response in mice challenged with L. amazonensis and L. pifanoi. To explore the potential of a DNA-based vaccine, we tested the L. amazonensis gene encoding P4 nuclease as well as adjuvant constructs encoding murine interleukin-12 (IL-12) and L. amazonensis HSP70. Susceptible BALB/c mice were immunized with the DNA encoding P4 alone, P4/IL-12, or P4/HSP70 prior to challenge with L. amazonensis promastigotes. Mice given P4/IL-12 exhibited no lesion development and had a 3- to 4-log reduction in tissue parasite burdens compared to controls. This protection corresponded to significant increases in gamma interferon and tumor necrosis factor alpha production and a reduction in parasite-specific immunoglobulin G1, suggesting an enhancement in Th1 responses. Moreover, we immunized mice with the L. amazonensis vaccines to determine if this vaccine regimen could provide cross-protection against a genetically diverse species, L. major. While the P4/HSP70 vaccine led to self-healing lesions, the P4/IL-12 vaccine provided negligible protection against L. major infection. This is the first report of successful use of a DNA vaccine to induce protection against L. amazonensis infection. Additionally, our results indicate that different vaccine combinations, including DNA encoding P4, HSP70, or IL-12, can provide significant protection against both Old World and New World cutaneous leishmaniasis.

Leishmanial infection: analysis of its first steps. A review

The first steps in leishmaniasis are critical in determining the evolution of the disease. Major advances have recently been done in understanding this crucial moment. Fundamental research in parasite-vector interaction, parasite biology, insect saliva, and vertebrate host response have shed new light and uncovered a most fascinating and complex moment in leishmaniasis. We review here some of these aspects and we try to connect them in a logical framework.

Immunoprotective haem oxygenase induction by ultraviolet A (320-400 nm) radiation in the mouse is inhibited in interferon-gamma null mice

BACKGROUND

A protective role for the ultraviolet (UV) A waveband against immunosuppression induced by UVB (280-320 nm) radiation has been identified. The mechanism for UVA immunoprotection was found to involve two apparently unrelated mediators, the T-helper-1-associated proinflammatory cytokine interferon (IFN)-gamma and the UVA-induced redox-regulated stress protein, haem oxygenase (HO).

OBJECTIVES

To identify a relationship between these two immune regulators.

METHODS

The HO response to UVA radiation in the skin and liver was examined in mice with a targeted disruption of the IFN-gamma gene, known to be unresponsive to UVA photoimmunoprotection. Results IFN-gamma null mice did not respond to UVA irradiation with the normal upregulation of HO activity in either the irradiated skin or the liver. Injection of these mice with recombinant IFN-gamma previously shown to restore the UVA-photoimmunoprotective effect, here partially and dose-responsively restored their ability for induction of HO activity in both skin and liver following UVA irradiation.

CONCLUSIONS

IFN-gamma appears to be a prerequisite for the immunoprotective induction of HO, although other mediators may also be involved. The UVA responsiveness of HO in an internal organ such as the liver suggests the existence of a soluble UVA-induced mediator from the skin, which may be IFN-gamma.

Low-dose UVB contributes to host resistance against Leishmania amazonensis infection in mice through induction of gamma interferon and tumor necrosis factor alpha cytokines

UV radiation suppresses the immune response, a fact which raises the question of whether the phenomenon may find practical applications in the outcome of infectious diseases. In this study, BALB/c mice were exposed to low-dose UVB (250 J/m(2)) from Dermaray M-DMR-100 for 4 consecutive days. Twelve hours after the last UV exposure, groups of mice were injected with 2 x 10(6) Leishmania amazonensis promastigotes. The development of skin lesions, as assessed by measurement of visible cutaneous lesions, was significantly suppressed in low-dose UVB-irradiated mice compared to nonirradiated controls. In order to characterize the cytokines involved in this phenomenon, BALB/c mice were irradiated with identical doses of UVB, and gamma interferon (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), and interleukin 4 cytokine levels in blood serum and skin were examined at different times by a sandwich enzyme-linked immunosorbent assay, immunohistochemical analysis, and reverse transcription (RT)-PCR. Upregulated expression of serum IFN-gamma and TNF-alpha was observed from 6 to 24 h. Positive results for IFN-gamma and TNF-alpha in UVB-irradiated mice were obtained by immunohistochemical analysis. By RT-PCR, the mRNA expression of both IFN-gamma and TNF-alpha cytokines was detected in a time-dependent manner only in UVB-irradiated mice. Histopathological analysis and electron microscopy revealed that cellular infiltration, tissue parasitism, and parasitophorus vacuoles in irradiated mice were markedly less noticeable than those in nonirradiated controls. These results suggested that low-dose UVB irradiation played a pathogen-suppressing role in Leishmania-susceptible BALB/c mice via systemic and local upregulation of Th1 (IFN-gamma and TNF-alpha) cytokines.