On the enigma of pain and hyperalgesia: A molecular perspective

Determination of soluble tumor necrosis factor receptor II and secretory immunoglobulin A in saliva of patients with dementia

The prevalence of pain and dementia increases with age, affecting a significant percentage of the population due to aging. Both pathologies are connected through the inflammatory process, specifically through the tumor necrosis factor. The effect of this cytokine is mediated through the modulation of its TNFRI and TNFRII receptors, which are linked to the dementia process. In addition, immunoglobulins such as secretory immunoglobulin A (sIgA) have been recognized as one of the main biomarkers of pain in saliva. sTNFRII and sIgA levels were determined in saliva samples by ELISA from healthy people and patients with dementia in GDS stages 5-7. The concentrations of these markers were also correlated with the GDS stage and sex. We observed a significant decrease (*** p ≤ 0.001) in the levels of sTNFRII (pg/mL) and a significant increase (** p ≤ 0.01) in the levels of sIgA (ng/mL) in the saliva of patients with dementia compared to the healthy control group. We did not observe a correlation with the data of the biomarkers regarding the GDS stage and sex. The results obtained for sTNFRII are consistent with those obtained by other authors on brain tissue, who conclude that unopposed neuronal TNFRI signaling, when TNFRII is selectively downregulated, leads to a more severe course of AD pathogenesis. Regarding sIgA, the elevated values of sIgA may reflect the immune status of these patients. Therefore, these biomarkers can provide us with relevant information through a non-invasive method such as saliva analysis.

The importance of inflammatory biomarkers in non-specific acute and chronic low back pain: a systematic review

OBJECTIVE

The purpose of this study was to systematically review the evidence on inflammatory biomarkers as analytic predictors of non-specific low back pain (NsLBP). Low back pain (LBP) is the number one cause of disability globally, posing a major health problem that causes an enormous social and economic burden, and there is an increasing interest on the importance of biomarkers in quantifying and even emerge as potential therapeutic tools to LBP.

METHODS

A systematic search was conducted on July 2022 in Cochrane Library, MEDLINE and Web of Science for all the available literature. Cross-sectional, longitudinal cohort or case-control studies that evaluated the relationship between inflammatory biomarkers collected from blood samples and low back pain in humans were considered eligible for inclusion, as well as prospective and retrospective studies.

RESULTS

The systematic database search resulted in a total of 4016 records, of which 15 articles were included for synthesis. Sample size comprised a total of 14,555 patients with LBP (acute LBP (n = 2073); chronic LBP (n = 12482)) and 494 controls. Most studies found a positive correlation between classic pro-inflammatory biomarkers and NsLBP, namely C-reactive protein (CRP), interleukin 1 (IL-1) and IL-1β, interleukin 6 (IL-6) and tumour necrosis factor α (TNF-α). On the other hand, anti-inflammatory biomarker interleukin 10 (IL-10) demonstrated a negative association with NsLBP. Four studies have made direct comparisons between ALBP and CLBP groups regarding their inflammatory biomarkers profile.

CONCLUSIONS

This systematic review found evidence of increased levels of pro-inflammatory biomarkers CRP, IL-6 and TNF-α and decreased levels of anti-inflammatory biomarker IL-10 in patients with LBP. Hs-CRP was not correlated with LBP. There is insufficient evidence to associate these findings with the degree of pain severity or the activity status of the lumbar pain over time.

Chronic Post-Surgical Pain in the Frail Older Adult

Older adults are the fastest growing segment of the population and surgical procedures in this group increase each year. Chronic post-surgical pain is an important consideration in the older adult as it affects recovery, physical functioning, and overall quality of life. It is increasingly recognized as a public health issue but there is a need to improve our understanding of the disease process as well as the appropriate treatment and prevention. Frailty, delirium, and cognition influence post-operative outcomes in older adults and have been implicated in the development of chronic post-surgical pain. Further research must be conducted to fully understand the role they play in the occurrence of chronic post-surgical pain in the older adult. Additionally, careful attention must be given to the physiologic, cognitive, and comorbidity differences between the older adult and the general population. This is critical for elucidating the proper chronic post-surgical pain treatment and prevention strategies to ensure that the older adult undergoing surgical intervention will have an appropriate and desirable post-operative outcome.

A systematic review of the role of inflammatory biomarkers in acute, subacute and chronic non-specific low back pain

Background

Low back pain (LBP) is one of the greatest contributors to disability in the world and there is growing interest on the role of biomarkers in LBP. To purpose of this review was to analyze available evidence on the relationship between inflammatory biomarkers, clinical presentation, and outcomes in patients with acute, subacute and chronic non-specific low back pain (NSLBP).

Methods

A search was performed in Medline, Embase, Cinahl and Amed databases. Studies which measured levels of inflammatory biomarkers in participants with NSLBP were included. Two reviewers independently screened titles and abstracts, full-texts, and extracted data from included studies. Methodological quality was assessed using the Newcastle Ottawa Quality Assessment Scale. Level of evidence was assessed using the modified GRADE approach for prognostic studies.

Results

Seven primary studies were included in this review. All results assessed using the modified GRADE demonstrated low to very low quality evidence given the small number of studies and small sample. Three studies examined C-reactive protein (CRP), one of which found significantly higher CRP levels in an acute NSLBP group than in controls and an association between high pain intensity and elevated CRP. Three studies examined tumor necrosis factor alpha (TNF-α), two of which found elevated TNF-α in chronic NSLBP participants compared to controls. Two studies examined interleukin 6 (IL-6), none of which found a significant difference in IL-6 levels between NSLBP groups and controls. Two studies examined interleukin 1 beta (IL-β), none of which found a significant difference in IL-β levels between NSLBP groups and controls.

Conclusions

This review found evidence of elevated CRP in individuals with acute NSLBP and elevated TNF-Α in individuals with chronic NSLBP. There are a limited number of high-quality studies evaluating similar patient groups and similar biomarkers, which limits the conclusion of this review.

TNF-α and sTNF-RII Are Associated with Pain Following Hip Fracture Surgery in Older Adults

Objective

To explore whether plasma inflammatory mediators on postoperative day 3 (POD3) are associated with pain scores in older adults after hip fracture surgery.

Design

Cross-sectional study.

Setting

Mount Sinai Hospital, New York, New York.

Subjects

Forty patients age 60 years or older who presented with acute hip fracture at Mount Sinai Hospital between November 2011 and April 2013.

Methods

Plasma levels of six inflammatory mediators of the nuclear factor kappa B pathway were measured using blood collected on POD3. Self-reported pain scores (i.e., pain with resting, walking, and transferring) were assessed at baseline (prefracture) and on POD3. Linear regression models using log-transformed data were performed to determine associations between inflammatory mediators and postoperative pain.

Results

Interleukin 18 (IL-18) was positively associated with POD3 resting pain score in the unadjusted model (β = 0.66, P = 0.03). Tumor necrosis factor α (TNF-α) and soluble TNF receptor II (sTNF-RII) were positively associated with POD3 resting pain score in the adjusted model (β = 0.99, P = 0.03, and β = 0.86, P = 0.04, respectively). Moreover, TNF-α was positively associated with POD3 walking pain score in the adjusted model (β = 1.59, P = 0.05). Pain with transferring was not associated with these inflammatory mediators.

Conclusions

These findings suggest that TNF-α and its receptors may influence pain following hip fracture. Further study of the TNF-α pathway may inform future clinical applications that monitor and treat pain in the vulnerable elderly who are unable to accurately report pain.

Biomarkers of inflammation in major vascular surgery: a prospective randomised trial

BACKGROUND

Surgery induces inflammation and pro-inflammatory cytokines are associated with post-operative complications. In cardiac surgery, it has been shown that volatile anaesthetics have cardioprotective properties. We explored whether sevoflurane affects the pro-inflammatory response favourably compared with total intravenous anaesthesia (TIVA) after surgery.

METHODS

We measured monocyte chemotactic protein 1 (MCP-1), matrix metalloproteinase 9 (MMP-9), C-reactive protein (CRP), vascular cell adhesion molecule 1 (VCAM-1), interleukin (IL)-6 and IL-8 perioperatively and evaluated if the anaesthetic regimen affected these mediators. Our hypothesis was that sevoflurane-based anaesthesia is associated with a reduced release of biomarkers of inflammation compared with TIVA with propofol/remifentanil.

RESULTS

In the total population, MCP-1, MMP-9, IL-6 and IL-8 increased 30 min after arrival intensive care unit, compared with before surgery (P < 0.001), whereas CRP and VCAM-1 transiently declined (P < 0.001). From 30 min after arrival intensive care unit to 1st post-operative day, MCP-1 and IL-6 levels declined (P < 0.001), CRP and VCAM-1 increased (P < 0.001), whereas MMP-9 and IL-8 were not significantly altered. Pre-operatively there were no significant differences in any variables between the two anaesthetic groups. Lower levels of MCP-1 and IL-8 (P < 0.001) and higher levels of IL-6 and MMP-9 (P = 0.003) were found in the sevoflurane group, compared with the TIVA group 30 min post-operatively. CRP and VCAM-1 levels did not differ. There were no significant differences between the two anaesthetic groups before surgery or at 1st post-operative day.

CONCLUSION

We found an inflammatory response during the observation period, which was modified by the anaesthetic regimen in the early phase. This short-lasting difference is probably too short to support a cardioprotective effect of sevoflurane compared with TIVA in open abdominal aortic surgery.

Effects of high-velocity, low-amplitude manipulation on catalase activity in men with neck pain

OBJECTIVE

The aim of this study was to identify the influence of high-velocity, low-amplitude (HVLA) manipulation on lipid peroxidation and catalase activity in subjects with neck pain who answered the Neck Disability Index and quadruple visual scale questionnaires.

METHODS

Twenty-two men (mean age, 38 years) with neck pain were recruited through radio and newspaper advertisements in the local media. Every patient received 6 sessions of HVLA manipulation, 3 times a week for 2 weeks. Blood samples were drawn from the cubital vein before treatment in the first session and after the third and sixth sessions. The quadruple visual scale was used with the same scheme. The Neck Disability Index questionnaire was applied before the beginning of treatment and after the last session. Catalase activity and lipoperoxidation were measured in erythrocyte samples.

RESULTS

Results showed no change in lipid peroxidation. Nevertheless, the catalase activity was increased by HVLA manipulation. The same treatment reduced pain perception and disability in these subjects.

CONCLUSION

The present study has shown that catalase activity of the erythrocytes, but not lipoperoxidation, increased after 6 sessions of HVLA manipulation treatment in men with neck pain. The results support the beneficial role of HVLA in the treatment of patients with neck pain.

Levo-tetrahydropalmatine retards the growth of ectopic endometrial implants and alleviates generalized hyperalgesia in experimentally induced endometriosis in rats

One primary goal of medical treatment of endometriosis is to alleviate pain and there is a pressing need for new therapeutics for endometriosis with better efficacy and side-effect profiles. Levo-tetrahydropalmatine (l-THP) has been used as a sedative or analgesic for chronic pains in China since 1970s. In this study, we sought to evaluate the efficacy of l-THP, with or without valproic acid (VPA), in a rat model of endometriosis. We surgically induced endometriosis in 55 adult female rats. Two weeks after, all rats were further divided into 5 groups randomly: untreated, low- and high-dose of l-THP, VPA, and l-THP + VPA. Response latency in hotplate test was measured before the surgery, before and after 3-week treatment of respective drugs. All rats were then sacrificed for analysis. The average lesion size and the immunoreactivity to N-methyl-D-asparate receptor 1 (NMDAR1), acid-sensing ion channel 3 (ASIC3), calcitonin gene-related peptide (CGRP), c-Fos, tyrosine kinase receptor A (TrkA), and histone deacetylase 2 (HDAC2) in dorsal root ganglia (DRG), to phorphorylated p65, HDAC2, TrkA, and CGRP in ectopic endometrium and to phorphorylated p65 and CGRP in eutopic endometrium were evaluated. We found that rats receiving l-THP, with or without VPA, had significantly reduced lesion size and exhibited significantly improved response to noxious thermal stimulus. The treatment also significantly lowered immunoreactivity to all mediators involved in central sensitization and to HDAC2 in DRG, to TrkA and CGRP in ectopic endometrium, and to CGRP in eutopic endometrium. In summary, l-THP reduces lesion growth and generalized hyperalgesia. Thus, l-THP may be a promising therapeutics for endometriosis.

The inhibitory effects of Gelam honey and its extracts on nitric oxide and prostaglandin E(2) in inflammatory tissues

We investigated the effects of honey and its methanol and ethyl acetate extracts on inflammation in animal models. Rats' paws were induced with carrageenan in the non-immune inflammatory and nociceptive model, and lipopolysaccharide (LPS) in the immune inflammatory model. Honey and its extracts were able to inhibit edema and pain in inflammatory tissues as well as showing potent inhibitory activities against NO and PGE(2) in both models. The decrease in edema and pain correlates with the inhibition of NO and PGE(2). Phenolic compounds have been implicated in the inhibitory activities. Honey is potentially useful in the treatment of inflammatory conditions.

The role of inflammatory cytokines and NF-kappaB/MAPK signaling pathways in the evolution of familial Mediterranean fever: current clinical perspectives and potential therapeutic approaches

Familial Mediterranean fever (FMF) is one of the social and health care problems for several populations that is known as a historically endemic disease of inflammatory nature. FMF, albeit a rare disorder, is characterized by recurrent fevers and painful inflammation of various body parts, especially the abdomen, lungs, and joints. FMF is typically characterized by inflammation of the abdominal lining (peritonitis), inflammation of the lining surrounding the lungs (pleurisy), painful, swollen joints (arthralgia and occasionally arthritis), and a characteristic ankle rash, a condition that is referred to as recurrent polyserositis, or familial paroxysmal polyserositis. Moreover, FMF is an inherited inflammatory disorder usually occurring in people of Mediterranean origin - including Sephardic Jews, Arabs, Armenians, and Turks; but it may ostensibly affect any other ethnic group, however, rarely. While there's no cure for this disorder, FMF is typically diagnosed during childhood, and signs and symptoms are treatable - or even preventable - by specialized medical attrition. The inflammatory signaling pathways associated with the evolution of FMF are currently being unraveled has that has therapeutic repercussions. In this review, I recap major concepts associated with the cellular and molecular immunology of FMF, especially shedding light on the likely roles of inflammatory cytokines, the transcription factor nuclear factor (NF)-kappaB, and the superfamily of mitogen-activated protein kinases (MAPKs). Furthermore, I summarize current advances for the clinical treatments available for FMF.

On the mechanisms and putative pathways involving neuroimmune interactions

Bidirectional interdependence between the immune system and the CNS involves the intervention of common cofactors. Cytokines are endogenous to the brain, endocrine and immune systems. These shared ligands are used as a chemical language for communication. Such interaction suggests an immunoregulatory role for the brain, and a sensory function for the immune system. Interplay between the immune, nervous and endocrine systems is associated with effects of stress on immunity. Cytokines are thus capable of modulating responses in the CNS, while neuropeptides can exert their effects over cellular groups in the immune system. One way is controlled by the HPA axis, a coordinator of neuroimmune interactions that is essential to unravel in order to elucidate vital communications in a manner that this crosstalk remains a cornerstone in perpetuating a stance of homeostasis.