Human Papillomavirus E7 Oncoprotein Transgenic Skin Develops an Enhanced Inflammatory Response to 2,4-Dinitrochlorobenzene by an Arginase-1-Dependent Mechanism

Abstract

We have shown that expression of Human Papillomavirus type 16 E7 (HPV16.E7) protein within epithelial cells, as occurs in HPV associated-premalignancy and cancers, results in local immune suppression, and a weak and ineffective immune response to E7 protein. However, a robust acute inflammatory stimulus can overcome this to enable immune elimination of HPV16.E7 transformed epithelial cells. 2,4-Dinitrochlorobenzene (DNCB) can elicit acute inflammation and has been shown to initiate the regression of HPV-associated genital warts. Although clinical use of DNCB is discouraged due to its mutagenic potential, understanding how DNCB induced acute inflammation alters local HPV16.E7 mediated-immune suppression might lead to better treatments. Here, we show that topical DNCB application to skin expressing HPV16.E7 as a transgene induces a hyperinflammatory response, not seen in non-transgenic control animals. The E7 associated-inflammatory response is characterized by enhanced expression of Th2 cytokines and increased infiltration of CD11b+Gr1intF4/80+Ly6ChiLy6Glow myeloid cells, producing arginase-1. Inhibition of arginase with an arginase specific inhibitor, N(omega)-hydroxy-nor-L-arginine, ameliorates the DNCB-induced inflammatory response. Our results demonstrate that HPV16.E7 protein enhances DNCB associated-production of arginase-1 by myeloid cells and consequent inflammatory cellular infiltration of skin.

Interleukin-17A Promotes Arginase-1 Production and 2,4-Dinitrochlorobenzene-Induced Acute Hyperinflammation in Human Papillomavirus E7 Oncoprotein-Expressing Skin

“…We have previously demonstrated that HPV16.E7-expressing skin exposed to DNCB develops a hyperinflammatory response, which is associated with recruitment of myeloid cells producing arginase-1, and that arginase-1 activity contributes to the enhanced inflammation [11]. Here, ex vivo skin explant culture supernatants induced enhanced arginase activity in BMDMs in immunocompetent and Rag -/- mice, confirming that arginase-1 induction in K14.E7 skin exposed to DNCB was dependent on innate immune cells rather than T and B lymphocytes [11]. …”

“…Although clinical application of DNCB has been discouraged due to its potent mutagenic, genotoxic and carcinogenic hazards [10], we hypothesised that understanding how DNCB-induced acute inflammation can alter the local immunosuppressive environment generated by HPV16.E7 oncoprotein might lead to better treatment options for patients with persistent HPV infection. Our recent study showed that treatment of K14.E7 skin with DNCB causes a hyperinflammatory response, which is associated with enhanced recruitment of myeloid cells producing arginase-1, and that arginase-1 is required for the development of DNCB-induced hyperinflammation [11]. However, the molecular mechanisms regulating arginase-1 induction, as well as how arginase-1 regulates the hyperinflammation in K14.E7 skin, have not been elucidated.…”

Tumor Necrosis Factor Receptor Mediates Fibroblast Growth Factor-Inducible 14 Signaling

“…HPV16 infection itself promotes the proliferation of keratinocytes, as well as switches keratinocytes from apoptotic to proliferative fate on TWEAK/Fn14 activation [9]. HPV infection triggers inflammatory responses that are characterized by an upregulated expression of Th2 cytokines [39]. The expressions of IL-1β, IL-4, IL-6, IL-10, interferon-γ, and TNF-α increase in skin of transgenic mice expressing the HPV16 E7 oncoprotein within basal keratinocytes [39].…”

“…HPV infection triggers inflammatory responses that are characterized by an upregulated expression of Th2 cytokines [39]. The expressions of IL-1β, IL-4, IL-6, IL-10, interferon-γ, and TNF-α increase in skin of transgenic mice expressing the HPV16 E7 oncoprotein within basal keratinocytes [39]. However, whether these cytokines participate in the TWEAK-induced proliferation of keratinocytes remains unclear.…”

Model systems to study the life cycle of human papillomaviruses and HPV-associated cancers

“…Other double transgenic mice show that Wnt/ β-catenin signaling (Bulut and Üren, 2015) and Fanconi anemia deficiency promote viral carcinogenesis (Park et al, 2013. It is worth noting that because the transgenic mice are immune competent, they are also being used to investigate interactions of HPV with the mice immune systems (Gosmann et al, 2014a(Gosmann et al, , 2014bTran et al, 2014).…”