Quinolone-photoconjugated major histocompatibility complex class II-binding peptides with lysine are antigenic for T cells mediating murine quinolone photoallergy

Photosensitivity and cancer immune-targeted therapies

The novel group of immunological agents used for solid tumors has importantly improved the quality of life and the survival rate of oncologic patients. Compared to conventional chemotherapy agents, they are more effective and less toxic. However, adverse cutaneous effects are commonly observed, and in some cases, they may induce treatment discontinuation, with heavy impact on patient prognosis. Among these, photosensitive reactions, either phototoxic or photoallergic, are increasing. Much remains to be clarified on the understanding of their prevention, diagnosis, and management. We have reviewed the literature about photosensitive reactions occurring during oncologic immunotherapies. Early dermatological diagnosis and adequate management, with oncologist's cooperation, is fundamental.

Stimulation of Langerhans cells with ketoprofen plus UVA in murine photocontact dermatitis to ketoprofen

BACKGROUND

Ketoprofen (KP) clinically evokes the allergic type of photocontact dermatitis when applied to the skin and irradiated with ultraviolet A (UVA). We have established a murine model of photocontact dermatitis to KP, which is a T cell-mediated delayed type hypersensitivity.

OBJECTIVE

To further explore the mechanism underlying this sensitivity, we investigated whether KP plus UVA activates the antigen-presenting ability of Langerhans cells (LCs).

METHODS

We analyzed the expression of surface molecules on LCs in the murine epidermis treated with KP plus UVA by immunohistochemistry and flow cytometry. Changes in the cytokine expression of epidermal cells from KP-phototreated skin were also examined by real-time PCR.

RESULTS

LCs became larger after treatment with KP plus UVA. The number of LCs was significantly decreased 2-3 days after KP phototreatment and recovered on day 5. A flow cytometric analysis revealed that KP plus UVA increased the percentage of LCs that highly expressed MHC class II, CD86, CD80, CD54 and CD40, whereas neither KP nor UVA alone enhanced the expression. KP phototreatment augmented the expression of I-A and CD86 on LCs in KP and UVA dose-dependent manners. A real-time PCR analysis of KP-phototreated skin showed that the expression of mRNA for IL-1alpha and GM-CSF was immediately increased after treatment.

CONCLUSION

A photosensitizing regimen of KP plus UVA activates LCs at least partly by stimulating keratinocytes to produce cytokines. Two strains of mice (BALB/c and AKR) differ in responsiveness to KP and the difference is not related to the activation of keratinocytes.

Induction of keratinocyte apoptosis by photosensitizing chemicals plus UVA

BACKGROUND

The capacity of photosensitizing chemicals with ultraviolet A light (UVA) to induce apoptosis is one of the methods to assess their phototoxic and potentially photoallergic properties, since apoptotic cells may be easily presented by antigen-presenting cells.

OBJECTIVES

We examined the photoaggravated ability to induce keratinocyte apoptosis of various chemicals that are known as causative agents of photocontact dermatitis and drug photosensitivity involving photoallergic and/or phototoxic mechanisms.

METHODS

HaCaT keratinocytes were incubated with 3,3',4',5-tetrachlorosalicylanilide (TCSA), bithionol, diphenylhydramine, chlorpromazine, 6-methylcoumarin, sparfloxacin, and enoxacin at 10(-7) to 10(-4)M and irradiated with UVA at 4J/cm(2). As positive control, 8-methoxypsoralen (8-MOP) was also tested. Apoptosis and necrosis were evaluated by flow cytometric enumeration of annexin V(+) 7-AAD(-) and annexin V(+) 7-AAD(+) cells, respectively. The expression of apoptosis-related molecules, caspase-3 and poly (ADP-ribose) polymerase (PARP), was tested by flow cytometric and Western blotting analyses.

RESULTS

In a comparison with non-irradiated cells, significant apoptosis was found in TCSA, bithionol, chlorpromazine, sparfloxacin and enoxacin at 10(-4) or 10(-5)M as well as 8-MOP as assessed by both annexin V and active caspase-3 stainings, while necrosis occurred in most of these chemicals at 10(-4)M. Neither apoptosis nor necrosis was seen in diphenylhydramine or 6-methylcoumarin. PARP were activated in HaCaT cells phototreated with TCSA, bithionol and chlorpromazine.

CONCLUSIONS

We suggest that our method is useful for in vitro assessment of phototoxicity and potential photoallergenicity of chemicals.

Covalent modification of a melanoma-derived antigenic peptide with a natural quinone methide. Preliminary chemical, molecular modelling and immunological evaluation studies

A LigandFit shape-directed docking methodology was used to identify the best position at which the melanoma-derived MHC class-I HLA-A2-binding antigenic peptide ELAGIGILTV could be modified by attaching a small molecule capable of fitting at the interface of complementary determining regional (CDR) loops of a T-cell receptor (TCR) while triggering T-cell responses. The small molecule selected here for determining the feasibility of this alternative track to chemical alteration of antigenic peptides was the electrophilic quinone methide (+)-puupehenone (), a natural product that belongs to a family of marine metabolites capable of expressing immunomodulatory activities. A preliminary chemical reactivity model study revealed the efficacy of the thiol group of a cysteine (C) side-chain in its nucleophilic addition reaction with in a regio- and diastereoselective manner. The best TCR/HLA-A2 ligand [i.e., ELAGCGILTV-S-puupehenol ()] then identified by the LigandFit docking procedure was synthesized and used to pulse HLA-A2(+) T2 cells for T-cell stimulation. Among the ELAGIGILTV-specific T-cell clones we tested, five of them recognized the conjugate in spite of its low binding affinity for the HLA-A2 molecules. The resulting T-cell stimulation was determined through the intracytoplasmic secretion of IFN-gamma and the percentage of T-cells thus activated. These highly encouraging results indicate that small non-peptidic natural product-derived molecules attached onto the central part of an antigenic peptide can fit at the TCR/HLA-A2 interface with induction of T-cell responses.

Establishment of murine model of allergic photocontact dermatitis to ketoprofen and characterization of pathogenic T cells

BACKGROUND

Ketoprofen is well known to evoke the allergic type of photocontact dermatitis when it is applied to the skin and irradiated with ultraviolet A (UVA) light.

OBJECTIVE

We aimed to establish a murine model of this photosensitivity and to characterize pathogenic T cells concerned with the sensitivity.

METHODS

Various strains of mice were sensitized on two consecutive days by application of ketoprofen to the shaved abdomen and irradiation of the skin with UVA. Five days later, they were elicited with ketoprofen plus UVA on the earlobes. Immune lymph node cells and epidermal cells from the challenged sites were analyzed by RT-PCR.

RESULTS

Mice were successfully sensitized and challenged with 4% and 2% ketoprofen, respective, plus UVA at 20J/cm2. The responses in H-2k mice were higher than those in the other strains examined. Immune lymph node CD4+ or CD8+ cells from ketoprofen-photosensitized H-2k mice were transferred i.v. to naïve syngeneic recipients. Mice receiving CD4+ but not CD8+ cells exhibited ketoprofen photosensitivity, but transference of both CD4+ and CD8+ cell populations was more effective. Lymph node cells from photosensitized mice expressed high levels of mRNA for Th2 cytokine (IL-4) and Th2 chemokine receptor (CCR4) as well as Th1 cytokine (IFN-gamma) and Th1 chemokine receptor (CXCR3), as assessed by RT-PCR. In addition, epidermal cells from challenged earlobes expressed increased levels of both Th1 (TARC) and Th2 (Mig) chemokines.

CONCLUSION

It is considered that not only Th1 but also Th2 cells participate in the pathogenesis of murine photocontact dermatitis to ketoprofen.