Interrelationship between ultraviolet light and recurrent herpes simplex infections in man

A Comprehensive Overview of Epidemiology, Pathogenesis and the Management of Herpes Labialis

Herpes labialis remains exceedingly prevalent and is one of the most common human viral infections throughout the world. Recurrent herpes labialis evolves from the initial viral infection by herpes simplex virus type 1 (HSV-1) which subsequently presents with or without symptoms. Reactivation of this virus is triggered by psychosocial factors such as stress, febrile environment, ultraviolet light susceptibility, or specific dietary inadequacy. This virus infection is also characterized by uninterrupted transitions between chronic-latent and acute-recurrent phases, allowing the virus to opportunistically avoid immunity and warrant the transmission to other vulnerable hosts simultaneously. This review comprehensively evaluates the current evidence on epidemiology, pathogenesis, transmission modes, clinical manifestations, and current management options of herpes labialis infections.

A series of in vitro and human studies of a novel lip cream formulation for protecting against environmental triggers of recurrent herpes labialis

Purpose

These studies describe the testing of a novel, daily-use lip cream designed for individuals with lips prone to recurrent herpes labialis (RHL) that protects against environmental triggers.

Subjects and methods

In vitro occlusive and in vitro and in vivo photoprotection analyses, a characterization of normal vs dry lips, and a randomized, evaluator-blinded, clinical trial that assessed the lip cream in healthy subjects with dry lips were conducted. In the clinical trial, subjects applied the lip cream or were untreated and evaluated using transepidermal water loss (TEWL), corneometry, visual assessments of lip dryness, expert photographic evaluations, and subject-rated outcomes.

Results

The lip cream’s in vitro water vapor transmission rate (84.1 g/(m² h)) indicated moderate occlusivity. The lip cream, but not placebo or control (water), reduced ultraviolet A (UVA)- and UVB-induced DNA damage, and tumor necrosis factor-α (EpiDerm^FT) and pros-taglandin E₂ release (EpiDerm^FT and EpiGingival™). The lip cream’s in vivo sun protection factor (SPF) was 12.2 (lower confidence limit, 11.3) and SPF/UVA protection factor ratio was 0.9. The characterization of dry vs normal lips identified differences in moisturization. In the clinical trial, the lip cream significantly decreased TEWL (difference: −7.19 [95% CI: −11.41, −2.98]; P<0.01), increased corneometry (difference: 4.62 [95% CI: 1.05, 8.19]; P<0.05), and reduced visual dryness (difference: −1.48 [95% CI: 2.24, −0.71]; P<0.001) compared to untreated subjects. Significant benefits were also observed on expert photographic assessments of scaling (difference: −0.89 [95% CI: −1.75, −0.03]; P< 0.05), cupping (difference: −1.50 [95% CI: −2.30, −0.70]; P<0.001), and healthy appearance (difference: −1.44 [95% CI: −2.29, −0.58]; P<0.01); differences in overall healthy appearance were not significant (P=0.51). Subject-rated assessments indicated improvements in cracking, dryness, and flaking in the lip cream group but worsening in untreated subjects.

Conclusion

These studies indicate that this novel, daily-use lip cream protects against UV radiation, drying, and chapping, which are established environmental RHL triggers.

PEDF Reduces the Severity of Herpetic Simplex Keratitis in Mice

Purpose

The purpose of this study was to explore the effects of pigment epithelium derived factor (PEDF) and PEDF-derived peptides Mer44 and Mer34 on the severity of herpetic simplex keratitis (HSK) in mice.

Methods

Adult C57BL/6 mice were infected ocularly with the herpes simplex virus type 1 (HSV-1, McKrae strain) and injected subconjunctivally with PEDF, Mer44, or Mer34. Corneal nerve degeneration, neovascularization, sensitivity, neutrophils, macrophages and CD4+ T-cell infiltration, virus contents, and expressions of VEGF, PEDF, and proinflammatory factors were evaluated during acute period. The direct inhibitory effect of PEDF on HSV-1 replication was further evaluated in cultured monkey Vero cells.

Results

Following HSV-1 infection, corneal PEDF expression decreased at 3 and 7 days postinfection (dpi) but increased at 15 dpi, and returned to the similar level of normal mice at 45 dpi, which was accompanied with the progress of corneal nerve degeneration and neovascularization. Exogenous PEDF application attenuated corneal nerve degeneration and neovascularization and improved the impaired corneal sensitivity. Moreover, PEDF attenuated the neutrophils, but not macrophage or CD4+ T-cell infiltration, with the reduced expressions of IL-1β, IL-6, TNF-α, and VEGF. In addition, PEDF inhibited the replication of HSV-1 both in vitro and in mice. Mer44 attenuated corneal nerve degeneration more significantly than Mer34, whereas Mer34 inhibited corneal neovascularization.

Conclusions

PEDF and its derived peptides reduce the severity of herpetic simplex keratitis in mice, representing the potential therapeutic approach to control HSK lesions.

An unusual presentation of herpes simplex virus type 1 infection in a child

We describe an 11-year-old girl presenting with lichen simplex chronicus (LSC) and acute bilateral carpal tunnel syndrome (CTS) following herpes simplex virus type 1 (HSV-1) infection as evidenced by serological data and by detection of HSV-1 DNA in the blood with the use of PCR. Based on the literature search, this case represents the first childhood case of LSC and acute bilateral CTS following HSV-1 infection. The experience with this patient emphasizes the importance of serological tests and PCR as well as the other laboratory techniques for the accurate diagnosis and management of the disease.

Ultraviolet light and resistance to infectious diseases

Exposure to ultraviolet (UV) radiation, as in sunlight, can modulate immune responses in animals and humans. This immunomodulation can lead to positive health effects especially with respect to certain autoimmune diseases and allergies. However, UV-induced immunomodulation has also been shown to be deleterious. Experimental animal studies have revealed that UV exposure can impair the resistance to many infectious agents, such as bacteria, parasites, viruses, and fungi. Importantly, these effects are not restricted to skin-associated infections, but also concern systemic infections. UV radiation induces a multistep process, locally in the skin as well as systemically, that ultimately leads to immunosuppression. The first event is the absorption of "UV" photons by chromophores, or so-called photoreceptors, such as DNA and urocanic acid (UCA) in the upper cell layers of the skin. Upon absorption of UV radiation, trans-UCA isomerizes to the cis-isomer. Cis-UCA is likely the most important mediator of UV-induced immunosuppression, as this compound has been shown to modulate the induction of contact type hypersensitivity and delayed type hypersensitivity, allograft rejection, and the functions of monocytes and T-lymphocytes as well as natural killer cells. The real consequences of UV-induced immunomodulation on resistance to infectious diseases for humans are not fully known. Risk estimations have been performed through extrapolation of animal data, obtained from infection models, to the human situation. This estimation indicated that UV doses relevant to outdoor exposure can impair the human immune system sufficiently to have effects on resistance to infections, but also indicated that human data are necessary to further quantify and validate this risk estimation. Further information has been obtained from vaccination studies in human volunteers as ethical reasons prohibit studies with infectious agents. Studies in mice and human volunteers on the effects of prior UVB exposure on hepatitis B vaccination responses revealed suppressed cellular and humoral immune responses in mice but not in human volunteers. However, subgroups within the performed human volunteer study made by determination of cytokine polymorphisms or UVB-induced mediators, revealed that some individuals have suppressed hepatitis B vaccination responses after UVB exposure. Thus, it might be concluded that the human immune system can be affected by UVB exposure, and decreased resistance to infectious diseases can be expected after sun exposure.

UVB susceptibility as a risk factor to the development of lepromatous leprosy

BACKGROUNDS

Ultraviolet radiation B (UVRB) is the most important environmental factor capable of altering the immune function of human skin.

OBJECTIVE

To evaluate the association of the phenotypes of susceptibility or resistance to ultraviolet radiation B (UVRB) and the polar forms of leprosy.

MATERIAL AND METHODS

We evaluated 38 patients with lepromatous leprosy (LL) and 87 patients with tuberculoid (TT) leprosy, according to the classification by Ridley and Jopling (1966). All the patients were submitted to a test to determine the phenotypes of susceptibility or resistance to UVRB through the application of a 2% dinitrochlorobenzene (DNCB) disc to a previously irradiated area with twice the minimal erythema dose (MED). After 21 days, a similar disc soaked in 0.05% DNCB was applied to the scapular area (unexposed to UVRB) to check for sensitiveness, with reading of the results after 48 hours. The patients that showed a positive reaction to DNCB were considered resistant (UVB-R) and those who did not show any reaction were considered susceptible (UVB-S).

RESULTS

The frequency of UVB-S individuals was 63.2% (24 patients) in the LL group and 34.4% (30 patients) in the TT group (OR=3.26; IC=1.36 - 7.87; x(2)=7.73; p=0.005).

CONCLUSION

Our results suggest that UVB-susceptibility is a risk factor to the development of lepromatous leprosy (LL).

Discriminant analysis of DNA polymorphisms in herpes simplex virus type 1 strains involved in primary compared to recurrent infections

The restriction fragment length polymorphism (RFLP) was analyzed using a set of herpes simplex virus type 1 (HSV-1) strains isolated from oro-facial lesions (oro-facial site collection), which was composed of two subsets: one subset consisted of 57 strains from primary oro-facial lesions, and the other of 47 strains from recurrent oro-facial lesions of patients complicated by factors possibly triggering the recurrence (e.g. malignancy, operation, and treatment of dental caries). RFLP analysis was carried out previously on two other sets of HSV-1 strains: one set was from genital lesions (genital site collection), and the other was from non-genital lesions (non-genital site collection). Discriminant analysis was carried out on the three sets of HSV-1 strains: the criterion variable had two values of primary infection or recurrence, and the predictor variables were 20 RFLPs. The degrees of separation between primary infection and recurrence increased in the order oro-facial site collection, genital site collection, and non-genital site collection. The results of discriminant analysis in this study confirmed that reactivation of HSV-1 infection is influenced by triggering factors and the site of infection, thereby suggesting the capabilities of multivariate analysis (including discriminant analysis) with DNA polymorphisms for molecular epidemiological studies.

Perineal herpes simplex infection in bedridden geriatric patients

BACKGROUND

Herpes simplex virus (HSV) lesions are prone to reactivation and recurrence in response to various local or systemic triggering factors.

OBJECTIVE

To study the characteristics of five bedridden geriatric patients who presented with herpetic recurrences on the buttocks, gluteal cleft, and perianal region during hospitalization.

METHODS

Data were gathered regarding age, gender, reason for hospitalization, localization of lesions, clinical presentation, previous clinical diagnosis and topical treatments, immune status and immunosuppressant drug intake, as well as prior history of labial or genital herpes. A skin biopsy was taken for histologic examination and immunohistochemical viral identification. Viral culture and viral serology were performed and data regarding antiviral therapy were recorded.

RESULTS

The five patients (three women, two men) were aged >80 years and hospitalized for either severe drug-induced renal insufficiency (one case), severe pneumonia (two cases), or stroke causing restricted mobility (two cases). Numerous well demarcated, painful ulcerations developed in the perianal region of these patients, and one patient also presented with some vesicular lesions. The lesions had been confused with mycotic and/or bacterial infections for 10-14 days. No inguinal lymphadenopathies were present and there was no fever. None of the patients had a previous history of recurrent labial or genital HSV infections or HIV infection. Histology was suggestive of HSV infection in two of five patients. Immunohistochemistry identified HSV type I (three patients) and HSV type II (two patients) infections. Viral culture with immunofluorescence viral identification revealed HSV type I in one of the four patients in whom a swab for viral culture was taken. Serology revealed past HSV infection. All lesions cured gradually after 10-14 days of intravenous acyclovir (aciclovir) treatment.

CONCLUSION

Herpetic lesions of the perineal region represent a rare complication in bedridden geriatric patients in the absence of a previous history of HSV infections at the same site. Common traits of patients with this condition were the presence of numerous ulcerated lesions, prolonged time course, and confinement to bed. The latter probably modifies the skin condition, which triggers viral reactivation and favors cutaneous extension of the infection. Complementary diagnostic methods for viral detection and identification are mandatory.

The topical isoflavonoid NV-07alpha reduces solar-simulated UV-induced suppression of Mantoux reactions in humans

UV radiation suppresses delayed-type hypersensitivity responses to intradermally injected tuberculin purified protein derivative in Mantoux-positive individuals. The effect of the topically administered isoflavonoid NV-07alpha, a synthetic derivative of the isoflavonoid equol, on UV-induced suppression of Mantoux reactions was assessed in 18 healthy Mantoux-positive volunteers. A single, fixed dose of solar-simulated UV radiation was delivered to the volunteers' lower backs. Different concentrations of NV-07alpha or its vehicle were applied to different sites within the irradiated field immediately after UV exposure and again 24 h later. Forty-eight hours after irradiation, Mantoux testing was performed at both the irradiated sites and adjacent, unirradiated sites. The intensity of Mantoux reactions was measured 72 h later with a reflectance erythema meter and by measuring the diameter of each reaction. Although lower concentrations of NV-07alpha (0.5 and 2 mM) did not prevent UV immunosuppression, 4 mM NV-07alpha partially but significantly attenuated UV-induced suppression of Mantoux-induced erythema. Minimal erythema doses were also determined for sites treated with NV-07alpha or its vehicle immediately after UV exposure. NV-07alpha had no significant effects on UV erythema. We conclude that 4 mM NV-07alpha prevented the suppressive effects of UV radiation on Mantoux responses in humans but did not affect UV-induced erythema at the concentrations used.

The Effect of Ultraviolet Radiation on Human Viral Infections

Exposure to UV radiation is recognized to suppress cell-mediated immunity and therefore could adversely affect the course of a viral infection. Rodent models of viral infection confirm this possibility but the situation in human subjects is not so clear, apart from two exceptions. These are herpes simplex, in which sunlight exposure can cause reactivation, and certain papillomavirus types in which sunlight exposure can lead to the development of nonmelanoma skin cancer. In both cases, there are UV response elements in the viral genomes that alter the normal interactions between the viruses and the host following exposure, and UV-induced effects on the immune response occur in addition. These complex mechanisms are discussed, and the situation regarding UV radiation and viral exanthems plus other viruses, including the retroviruses, summarized. Finally viral vaccination is considered in the context of UV exposure and the importance of the host's genetic background emphasized. Further research is required to evaluate whether sunlight can significantly affect the resistance to common viral infections and vaccines.

Sunlight exposure and (sero)prevalence of epidermodysplasia verruciformis-associated human papillomavirus

Ultraviolet radiation (UVR) is associated with an increased risk of squamous cell carcinoma (SCC), which is in part due to immunomodulation. In addition, human papilloma virus (HPV), especially the epidermodysplasia verruciformis (EV)-associated types, may be involved. In view of the capacity of UVR to impair host resistance to infections, we investigated the relationship between solar exposure and the prevalence of cutaneous HPV. In a case-control study on skin cancer (320 controls and 156 patients) a lifetime-retrospective questionnaire on sun exposure was administered. The presence of DNA of HPV types 5, 8, 15, 20, 24, and 38 in plucked eyebrow hair and type-specific seroreactivity were assessed and analyzed in relation to estimated exposure. Sunburn episodes in the past, especially at age 13-20 y, appeared to be associated with an enhanced risk of EV-HPV DNA positivity. In contrast, a higher lifetime sun exposure was associated with a lower risk of HPV infection. These results indicate that UVR at erythematogenic doses increases the risk of EV-HPV infection, possibly due to impaired host resistance to HPV and/or a direct effect of UVR on viral replication. The favorable association between lifetime sun exposure and HPV prevalence, however, underscores the enigmatic role of HPV in skin carcinogenesis.

Skin infections in renal transplant recipients and the relation with solar ultraviolet radiation

BACKGROUND

Ultraviolet radiation (UVR) is an important risk factor for skin cancer in transplant recipients. In view of the potential suppressive effect of UVR on host resistance it was examined whether exposure to UVR was also associated with the occurrence of various skin infections.

METHODS

In a cohort of renal transplant recipients (n = 137), lifetime exposure was assessed by means of a retrospective questionnaire on cumulative sunlight exposure. Diagnosed skin infections since renal transplantation were extracted from the patient's medical charts. Season of diagnosis was regarded as indicative of short-term exposure.

RESULTS

In comparison with winter a high rate of herpes simplex infections was found in spring [rate ratio (RR) = 4.09, 95% confidence interval (CI) 1.2-14.5], and high rates of herpes zoster infections (RR = 1.6, 95% CI: 0.8-3.5) and fungal/yeast infections in summer (RR = 2.1, 95% CI: 1.3-3.4). A higher lifetime exposure (RR = 2.31, 95% CI: 1.04-5.1) and a greater cumulative number of reported sunburns (RR = 2.3, 95% CI: 1.1-5.1) were independently associated with a higher risk of bacterial infections.

CONCLUSIONS

The seasonal association with the occurrence of clinical herpes infections indicates an effect of short-term UVR. Our data suggest that the number of sunburn episodes in the past is also relevant for the susceptibility to certain skin infections.

Treatment of mucocutaneous presentations of herpes simplex virus infections

Infections by herpes simplex virus (HSV) types I and II are diverse and quite frequent. After primary infection, the virus establishes a life-long latency in the sensory ganglia and recrudescences may occur at an unpredictable rate. Recurrent labial and genital herpes infections represent the majority of clinical manifestations of HSV infections. Their management is currently well established using evidence-based medicine data. Primary labial herpes is generally not treated with antivirals in otherwise healthy children, although intravenous aciclovir may be offered in severe primary infections, particularly in the immunocompromised patient. The decision whether or not to treat recurrent labial herpes should be evaluated individually and depends on the frequency and severity of relapses, the impairment of the quality of life, and the cost of therapy. Patients with mild disease may benefit from topical therapy, and those with severe and frequent recurrences may be considered for intermittent or long-term oral antiviral therapy. Primary genital herpes is treated with oral or intravenous antivirals, depending on the severity of the infection and associated symptoms. Recurrent genital herpes can be managed with episodic short courses of oral antivirals in patients whose recurrences are moderate to severe and rare, and have a clear prodrome. Patients with >5 episodes/year, severe recurrences or unrecognisable prodromes may be best managed with long-term suppressive antiviral prophylaxis. HSV is also responsible for a variety of other clinical manifestations, including herpetic whitlow, neonatal infection, disseminated and atypical cutaneous infections, traumatic herpes, eczema herpeticum, and HSV-associated erythema multiforme. HSV infection may also represent a complication following cosmetic procedures of the oro-facial region, surgical and dental interventions, sun exposure and burns. Precise treatment guidelines for these HSV infections are not firmly established.

Ultraviolet radiation, resistance to infectious diseases, and vaccination responses

Exposure to ultraviolet (UV) radiation, as in sunlight, can modulate immune responses in animals and humans. This immunomodulation can lead to positive health effects especially with respect to certain autoimmune diseases and allergies. However, UV-induced immunomodulation has also been shown to be deleterious. Experimental animal studies have revealed that UV exposure can impair resistance to many infectious agents, such as bacteria, parasites, viruses, and fungi. Importantly, these effects are not restricted to skin-associated infections, but also concern systemic infections. The real consequences of UV-induced immunomodulation on resistance to infectious diseases are not known for humans. Risk estimations have been performed through extrapolation of animal data, obtained from infection models, to the human situation. This estimation indicated that UV doses relevant to outdoor exposure can impair the human immune system sufficiently to have effects on resistance to infections. To further quantify and validate this risk estimation, data, e.g., from human volunteer studies, are necessary. Infection models in humans are not allowed for ethical reasons. However, vaccination against an infectious disease evokes a similar immune response as the pathogen and thereby provides an opportunity to measure the effect of UV radiation on the immune system and an estimate of the possible consequences of altered resistance to infectious agents. Effects of controlled UVB exposure on immune responses after hepatitis B vaccination have been established in mice and human volunteers. In mice, cellular and Th1-associated humoral immune responses to hepatitis B were significantly impaired, whereas in human volunteers no significant effect of UVB on these responses could be found. Preliminary data indicate that cytokine polymorphisms might be, at least in part, responsible for interindividual differences in immune responses and in susceptibility to UVB-induced immunomodulation. In addition, adaptation to UV exposure needs to be considered as a possible explanation for the difference between mice and humans that was observed in the hepatitis B vaccination model.

Effects of low-dose ultraviolet radiation on in vivo human cutaneous recall responses

Relatively few studies have examined the effects of low-dose ultraviolet (UV) radiation on in vivo human cutaneous immunity, or the ability of sunscreens to prevent UV-induced immunosuppression. We have studied the effects of solar-simulated UV radiation on nickel contact hypersensitivity (CHS) in nickel-allergic volunteers, and on delayed type hypersensitivity responses in Mantoux-positive volunteers. Nickel CHS and Mantoux responses were significantly suppressed by acute, suberythemal UV exposures equivalent to less than 8 min summer sunlight. Both UVA and UVB wavebands were immunosuppressive, but UVA-induced immunosuppression was transient, whereas UVB had a more sustained effect. Dose-responses for UV immunosuppression were determined using the nickel method, enabling calculation of in vivo sunscreen immune protection factors in a manner analogous with sun protection factor measurement. Sunscreens were found to confer significantly less protection against UV-induced immunosuppression than against UV-induced erythema.

Oxidative stress increases production of beta-amyloid precursor protein and beta-amyloid (Abeta) in mammalian lenses, and Abeta has toxic effects on lens epithelial cells

Many amyloid diseases are characterized by protein aggregations linked to oxidative stress. Such diseases including those of the brain, muscle, and blood vessels exhibit plaques containing beta-amyloid (Abeta). Here we demonstrate that Alzheimer's precursor protein (betaAPP) and A beta are present at low levels in normal lenses and increase in intact cultured monkey lenses treated with H2O2 or UV radiation (known cataractogenic agents), and with phorbol 12-myristate 13-acetate. AP-1 factor binding, shown by others to up-regulate betaAPP expression, increased in the monkey lenses treated with H2O2, UV radiation, or phorbol 12-myristate 13-acetate and paralleled the increase in betaAPP expression. Rat lenses exposed to oxidative stress showed increased betaAPP in the anterior epithelium and cortex. Incubation of cultured rabbit lens N/N1003A epithelial cells with Abeta induced inclusions and vacuoles and was cytotoxic. Abeta cross-reacting protein was readily detected in the cortex of a cataractous human lens. Our data show that betaAPP and Abeta increase in mammalian lenses as part of a response to H2O2 or UV radiation and suggest that they may contribute to the mechanism by which oxidative damage leads to lens opacification.