Persistence of a T Cell Infiltrate in Human Ganglia Years After Herpes Zoster and During Post-herpetic Neuralgia

Identifying and Evaluating Biological Markers of Postherpetic Neuralgia: A Comprehensive Review

Postherpetic neuralgia (PHN) manifests as persistent chronic pain that emerges after a herpes zoster outbreak and greatly diminishes quality of life. Unfortunately, its treatment efficacy has remained elusive, with many therapeutic efforts yielding less than satisfactory results. The research to discern risk factors predicting the onset, trajectory, and prognosis of PHN has been extensive. However, these risk factors often present as nonspecific and diverse, indicating the need for more reliable, measurable, and objective detection methods. The exploration of potential biological markers, including hematological indices, pathological insights, and supportive tests, is increasing. This review highlights potential biomarkers that are instrumental for the diagnosis, management, and prognosis of PHN while also delving deeper into its genesis. Drawing from prior research, aspects such as immune responsiveness, neuronal injury, genetic makeup, cellular metabolism, and pain signal modulation have emerged as prospective biomarkers. The immune spectrum spans various cell subtypes, with an emphasis on T cells, interferons, interleukins, and other related cytokines. Studies on nerve injury are directed toward pain-related proteins and the density and health of epidermal nerve fibers. On the genetic and metabolic fronts, the focus lies in the detection of predisposition genes, atypical protein manifestations, and energy-processing dynamics, with a keen interest in vitamin metabolism. Tools such as functional magnetic resonance imaging, electromyography, and infrared imaging have come to the forefront in the pain signaling domain. This review compiles the evidence, potential clinical implications, and challenges associated with these promising biomarkers, paving the way for innovative strategies for predicting, diagnosing, and addressing PHN.

Lichenoid lesions of the upper labial mucosa: a systematic review and a report of a new case with extensive follow-up

OBJECTIVES

The paper reports the demographic characteristics of patients with lichenoid lesions affecting only the upper labial mucosa, with or without associated lesions in the maxillary anterior gingiva, alongside the lesions' clinical and histopathological features, treatment, follow-up and prognosis. Also, a new case with lengthy follow-up is presented.

MATERIALS AND METHODS

A systematic review was performed in line with PRISMA guidelines. The literature search sources were PubMed, Scopus and Web of Science.

RESULTS

In all, 26 patients (21 women, 5 men) were included in the review. 80.8% (n = 21) of the labial lesions were clinically erythematous and 19.2% (n = 5) were accompanied by white striations. The gingiva was affected in 46.2% of cases. All patients (100%, n = 24) reported symptoms. All of the lesions presented histological features of lichenoid inflammation. Granulomas were noted in 65.4% (n = 17) of the lesions. Topical corticosteroid was the most frequent therapy (89.5%, n = 17).

CONCLUSIONS

Lichenoid lesions found solely in the upper labial mucosa, with or without adjacent gingival lesions, are rarely reported in the literature, and the reporting is often incomplete. A definitive aetiology could not be established for the lesions. Likewise, there is little information about this condition's long-term prognosis.

Selective retention of virus-specific tissue-resident T cells in healed skin after recovery from herpes zoster

Herpes zoster is a localized skin infection caused by reactivation of latent varicella-zoster virus. Tissue-resident T cells likely control skin infections. Zoster provides a unique opportunity to determine if focal reinfection of human skin boosts local or disseminated antigen-specific tissue-resident T cells. Here, we show virus-specific T cells are retained over one year in serial samples of rash site and contralateral unaffected skin of individuals recovered from zoster. Consistent with zoster resolution, viral DNA is largely undetectable on skin from day 90 and virus-specific B and T cells decline in blood. In skin, there is selective infiltration and long-term persistence of varicella-zoster virus-specific T cells in the rash site relative to the contralateral site. The skin T cell infiltrates express the canonical tissue-resident T cell markers CD69 and CD103. These findings show that zoster promotes spatially-restricted long-term retention of antigen-specific tissue-resident T cells in previously infected skin.

A new susceptibility index to predict the risk of severe herpes zoster-associated pain: A Japanese regional population-based cohort study, the Shizuoka study

BACKGROUND

Approximately 7-20% of patients with herpes zoster (HZ) develop zoster-associated pain (ZAP). ZAP not only impairs quality of life and psychological well-being, but also can reduce work effectiveness, which has negative economic effects. Reports of ZAP risk factors are inconsistent.

OBJECTIVE

To confirm risk factors for the development of severe ZAP in HZ patients in Japan using a large-scale database, the Shizuoka Kokuho Database.

METHODS

A population-based cohort study using the Shizuoka Kokuho Database was conducted. Of 792,647 patients, 7491 (0.95%) experienced "severe ZAP" (as defined in this study). We developed a ZAP risk prediction scoring system by identifying risk factors using logistic regression analysis of several candidate risk factors for severe ZAP: age, sex, seasonality, and presence of comorbidities (using the Charlson comorbidity index), excluding HIV/AIDS.

RESULTS

We identified peripheral vascular disease and the onset from October to December as novel risk factors for severe ZAP, in addition to the previously reported risk factors of age and comorbidities (cerebral vascular disease, chronic pulmonary disease, rheumatic disease, peptic ulcer, liver disease, diabetes, and malignant neoplasms with/without metastasis). In contrast, dementia was found to reduce ZAP risk. We developed a susceptibility index to predict the risk of ZAP.

CONCLUSION

We newly demonstrated that peripheral vascular disease and the onset from October to December are ZAP risk factors. Our comorbidity findings support previous observations. The susceptibility index proposed here provides a new approach to the prevention of ZAP using early intervention for high-risk patients.

Targeting Neuroimmune Interactions in Diabetic Neuropathy with Nanomedicine

Significance: Diabetes is a major source of neuropathy and neuropathic pain that is set to continue growing in prevalence. Diabetic peripheral neuropathy (DPN) and pain associated with diabetes are not adequately managed by current treatment regimens. Perhaps the greatest difficulty in treating DPN is the complex pathophysiology, which involves aspects of metabolic disruption and neurotrophic deficits, along with neuroimmune interactions. There is, therefore, an urgent need to pursue novel therapeutic options targeting the key cellular and molecular players. Recent Advances: To that end, cellular targeting becomes an increasingly compelling drug delivery option as our knowledge of neuroimmune interactions continues to mount. These nanomedicine-based approaches afford a potentially unparalleled specificity and longevity of drug targeting, using novel or established compounds, all while minimizing off-target effects. Critical Issues: The DPN therapeutics directly targeted at the nervous system make up the bulk of currently available treatment options. However, there are significant opportunities based on the targeting of non-neuronal cells and neuroimmune interactions in DPN. Future Directions: Nanomedicine-based agents represent an exciting opportunity for the treatment of DPN with the goals of improving the efficacy and safety profile of analgesia, as well as restoring peripheral neuroregenerative capacity. Antioxid. Redox Signal. 36, 122-143.

Recent Issues in Varicella-Zoster Virus Latency

Varicella-zoster virus (VZV) is a human herpes virus which causes varicella (chicken pox) as a primary infection, and, following a variable period of latency in neurons in the peripheral ganglia, may reactivate to cause herpes zoster (shingles) as well as a variety of neurological syndromes. In this overview we consider some recent issues in alphaherpesvirus latency with special focus on VZV ganglionic latency. A key question is the nature and extent of viral gene transcription during viral latency. While it is known that this is highly restricted, it is only recently that the very high degree of that restriction has been clarified, with both VZV gene 63-encoded transcripts and discovery of a novel VZV transcript (VLT) that maps antisense to the viral transactivator gene 61. It has also emerged in recent years that there is significant epigenetic regulation of VZV gene transcription, and the mechanisms underlying this are complex and being unraveled. The last few years has also seen an increased interest in the immunological aspects of VZV latency and reactivation, in particular from the perspective of inborn errors of host immunity that predispose to different VZV reactivation syndromes.

Protective role of natural killer cells in neuropathic pain conditions

ABSTRACT

During the past few years, the research of chronic neuropathic pain has focused on neuroinflammation within the central nervous system and its impact on pain chronicity. As part of the ERA-Net NEURON consortium, we aimed to identify immune cell patterns in the cerebrospinal fluid (CSF) of patients with herpes zoster neuralgia and patients with polyneuropathy (PNP), which may contribute to pain chronicity in these neuropathic pain conditions. Cerebrospinal fluid of 41 patients (10 herpes zoster and 31 PNP) was analyzed by flow cytometry identifying lymphocyte subsets: CD4+ (T-helper cells), CD8+ (cytotoxic T cells), CD19+ (B cells), and CD56+ (natural killer [NK]) cells. At baseline and at follow-up, the somatosensory phenotype was assessed with quantitative sensory testing. In addition, the patients answered epidemiological questionnaires and the PainDETECT questionnaire. Immune cell profiles and somatosensory profiles, as well as painDETECT questionnaire scores, were analyzed and correlated to determine specific immune cell patterns, which contribute to chronic pain. We found a negative correlation (P = 0.004, r = -0.596) between the frequency of NK cells and mechanical pain sensitivity (MPS), one of the most relevant quantitative sensory testing markers for central sensitization; a high frequency of NK cells correlated with low MPS. The analysis of the individual follow-up showed a worsening of the pain condition if NK-cell frequency was low. Low NK-cell frequency is associated with signs of central sensitization (MPS), whereas high NK-cell frequency might prevent central sensitization. Therefore, NK cells seem to play a protective role within the neuroinflammatory cascade and may be used as a marker for pain chronicity.