Patient characteristics and analgesic efficacy of antiviral therapy in postherpetic neuralgia

Genetic insights into the gut microbiota, herpes zoster, and postherpetic neuralgia: a bidirectional two-sample Mendelian randomization study

Background

An increasing amount of evidence suggests that gastrointestinal diseases are risk factors for herpes zoster (HZ) and postherpetic neuralgia (PHN). Among them, the gut microbiota may play a crucial role in this process. Therefore, this study aims to explore the potential causal association between the gut microbiota and HZ and PHN.

Methods

Bidirectional two-sample Mendelian randomization (MR) analysis was used to detect the causal effect between HZ and PHN and the gut microbiota. Gut microbiota data were derived from the MiBioGen consortium, while HZ and PHN data were obtained from the FinnGen database. We selected single-nucleotide polymorphisms (SNPs) as instrumental variables with a threshold of p < 1 × 10⁻⁵ for the association with the gut microbiota in forward MR analysis and p < 5 × 10⁻8 for the association with HZ or PHN in reverse MR analysis and then removed SNPs in linkage disequilibrium (r 2 < 0.001) within a distance of 10,000 kb for both the gut microbiota and HZ and PHN. These SNPs were utilized to assess the causal effect between exposures and outcomes using inverse-variance weighting (IVW), MR-Egger, weighted mean, and weighted median tests.

Results

The class Deltaproteobacteria, order Desulfovibrionales, family Desulfovibrionaceae, and genus Coprococcus 2 were found to reduce the risk of HZ, while the phylum Cyanobacteria, genus Eubacterium rectale group appeared to increase it. The class Coriobacteriia, order Coriobacteriales, family Coriobacteriaceae, genus Lachnospiraceae NK4A136 and genus Ruminococcaceae UCG011 were found to reduce the risk of PHN, while the genus Candidatus Soleaferrea, genus Eubacterium rectale group, and genus Methanobrevibacter appeared to increase it. Moreover, the onset of HZ was found to increase the level of the genus Eubacterium rectale group. These findings remained robust and unaffected by heterogeneity or horizontal pleiotropy among SNPs in both forward and reverse MR analysis.

Conclusion

This MR study provided evidence supporting a potential causal relationship between the gut microbiota and HZ and PHN. Moreover, we found that the causal effect between the gut microbiota and HZ is bidirectional. Further studies are required to clarify the biological mechanisms linking the gut microbiota and these conditions.

Botulinum toxin type A ameliorates rat dorsal root ganglia neuron pyroptosis in postherpetic neuralgia by upregulating cathelicidin antimicrobial peptide to inhibit neutrophil elastase

Botulinum toxin type A (BoNT/A) has exhibited efficacy in postherpetic neuralgia (PHN) treatment, and this study aims to uncover its underlying mechanisms. Resiniferatoxin (RTX)-induced PHN rats were given BoNT/A. Rat postoperative pain behaviors were assessed by Von Frey test. Cleaved-synaptosomal protein 25 kDa (cl-SNAP-25) or cathelicidin antimicrobial peptide (CAMP) expression in rat dorsal root ganglia (DRG) was detected by immunofluorescence or immunohistochemistry. Healthy rat-derived DRG neurons were transfected, incubated with lipopolysaccharides (LPS)/adenosine 5'-triphosphate (ATP) to stimulate pyroptosis and treated with BoNT/A. The CCK-8, Western blot, ELISA, and qRT-PCR were used to assess the viability, levels of pyroptosis-related proteins proinflammatory cytokine levels, as well as CAMP and ELANE mRNA levels. BoNT/A (30 U/kg) promoted cl-SNAP-25 expression in rat DRG and reversed RTX-induced decrease of rat paw withdrawal thresholds and CAMP expression and increase of pyroptosis-associated protein and inflammatory factor expression in rat DRG. CAMP interacted with ELANE in rat DRG neurons. BoNT/A attenuated LPS/ATP-stimulated inhibition of viability and CAMP expression and upregulation of inflammatory mediators, pyroptosis-related proteins, and ELANE expression in rat DRG neurons, which was counteracted by CAMP silencing. However, ELANE knockdown offset the effect of CAMP silencing in LPS/ATP/BoNT/A-treated rat DRG neurons. On the whole, BoNT/A alleviates rat DRG neuron pyroptosis during PHN by upregulating CAMP to inhibit ELANE.

Psychological Outcomes and Quality of Life of Fibromyalgia Patients with Vitamin D Supplementation-A Meta-Analysis

The efficacy of current pharmaceutical treatments for fibromyalgia are limited. Vitamin D has shown promise in relieving pain. However, there is a lack of comprehensive analysis of psychological outcomes with vitamin D supplementation in fibromyalgia. This study aimed to investigate the impact of vitamin D supplementation on psychological outcomes and quality of life in fibromyalgia patients, given the unmet clinical need for effective treatment options. A meta-analysis of randomized controlled trials comparing vitamin D to placebo and prospective studies examining changes before and after vitamin D supplementation for patients with fibromyalgia was conducted to evaluate the effects of vitamin D on psychological outcomes, quality of life, and pain scores in patients with fibromyalgia. Databases were searched for relevant articles published from earliest available date to October 31, 2022. (PROSPERO number, CRD42022369889). We included 8 trials with a total of 694 participants and found that vitamin D supplementation had significant positive effects on physical function (standard mean differences (SMD) = 0.44, 95% CI = [0.10, 0.77 ]), role limitations due to emotional health (SMD = 0.57, 95% CI = [0.32, 0.82]), social function (SMD = 0.50, 95% CI = [0.08, 0.93]), and general health (SMD = 0.36, 95% CI = [0.11, 0.61]). Improvement of the Fibromyalgia Impact Questionnaire (FIQ) scores was noted (SMD = -0.414, 95% CI = [-0.808, -0.021]), but not on the Visual Analog Scale (VAS) (SMD = -0.15, 95% CI = [-0.771, 0.471]) and the Beck's Depression Inventory (BDI) scores (SMD = -0.456, 95% CI = [-1.27, 0.30]). In conclusion, vitamin D supplementation might be an alternative option for improvement of psychological outcomes and quality of life in patients with fibromyalgia.

How far is vitamin D implicated in cutaneous infections

Vitamin D is an important cornerstone in the immunologic cascade of many skin infections, systemic infections with cutaneous presentations, and other infectious dermatologic diseases where infections could be a culprit. Vitamin D supplementation is proposed as a protective measure against their occurrence and exacerbation, especially with the emergence of several viral pandemics in recent years. Vitamin D plays a key role in the maintenance of a balanced immunologic profile which could be reflected by a lowered incidence and morbidity of infections. Vitamin D screening and supplementation in patients with deficiencies or insufficiencies should be a part of the dermatologic approach to patients with these diseases.

Dorsal root ganglion stimulation for refractory post-herpetic neuralgia

Post-herpetic neuralgia is a chronic neuropathic pain disorder that is the sequela of the varicella zoster virus reactivation in the dorsal root ganglion. A variety of treatment modalities have been implemented, but pharmacologic treatments are often limited due to side effects and interventional procedures have yielded mixed results without promising long-term benefits being consistently seen. A dorsal root ganglion stimulator for treatment of post-herpetic neuralgia is a novel treatment option as it is able to specifically target the area affected. We present 3 patients who underwent implantation of permanent dorsal root ganglion stimulators and had a greater than 50% decrease in scoring on numerical rating scale (NRS) up to 18 months post-procedure and significantly reduced analgesic requirements.

Hypovitaminosis Din Postherpetic Neuralgia-High Prevalence and Inverse Association with Pain: A Retrospective Study

Hypovitaminosis D (25-hydroxyvitamin D (25(OH)D) <75 nmol/L) is associated with neuropathic pain and varicella-zoster virus (VZV) immunity. A two-part retrospective hospital-based study was conducted. Part I (a case-control study): To investigate the prevalence and risk of hypovitaminosis D in postherpetic neuralgia (PHN) patients compared to those in gender/index-month/age-auto matched controls who underwent health examinations. Patients aged ≥50 years were automatically selected by ICD-9 codes for shingle/PHN. Charts were reviewed. Part II (a cross-sectional study): To determine associations between 25(OH)D, VZV IgG/M, pain and items in the DN4 questionnaire at the first pain clinic visit of patients. Independent predictors of PHN were presented as adjusted odds ratios(AOR) and 95% confidence intervals (CI). Prevalence (73.9%) of hypovitaminosis D in 88 patients was high. In conditional logistic regressions, independent predictors for PHN were hypovitaminosis D (AOR3.12, 95% CI1.73–5.61), malignancy (AOR3.21, 95% CI 1.38–7.48) and Helicobacter pylori-related peptic ulcer disease (AOR3.47, 95% CI 1.71–7.03). 25(OH)D was inversely correlated to spontaneous/brush-evoked pain. Spontaneous pain was positively correlated to VZV IgM. Based on the receiver operator characteristic curve, cutoffs for 25(OH)D to predict spontaneous and brush-evoked pain were 67.0 and 169.0 nmol/L, respectively. A prospective, longitudinal study is needed to elucidate the findings.