The Coming of Age of the P2X7 Receptor in Diagnostic Medicine

The discovery of the P2X7 receptor (P2X7R, originally named P2Z) in immune cells, its cloning, and the identification of its role in a multiplicity of immune-mediated diseases raised great hopes for the development of novel and more potent anti-inflammatory medicaments. Unfortunately, such hopes were partially deluded by the unsatisfactory results of most early clinical trials. This failure substantially reduced the interest of the pharmaceutical and biotech industries in the clinical development of P2X7R-targeted therapies. However, recent findings ushered in a second life for the P2X7R in diagnostic medicine. New P2X7R radioligands proved to be very reliable tools for the diagnosis of neuroinflammation in preclinical and clinical studies, and detection and measurement of free P2X7 receptor (or P2X7 subunit) in human blood suggested its potential use as a circulating marker of inflammation. Here we provide a brief review of these novel developments.

Anakinra treatment efficacy in reduction of inflammatory biomarkers in COVID-19 patients: A meta-analysis

Introduction

Anakinra is being empirically considered for the treatment of COVID‐19 patients. The aim is to assess the efficacy of anakinra treatment on inflammatory marker reduction, including c‐reactive protein (CRP) concentrations, serum ferritin, and serum d‐dimer levels.

Methods

Adhering to PRISMA 2020 statement guidelines, a systematic search was conducted across the following databases from December 2019 until January 10, 2022: PubMed/MEDLINE, Cochrane Central, Web of Science, Scopus, and EMBASE. The following keywords were employed: Anakinra, COVID*, SARS‐CoV‐2, inflammatory, CRP, D‐dimer, Ferritin, hematological, laboratory, clinical, trials. The findings were collated and presented in a tabulated manner, and statistically analyzed using Review Manger 5.4 (Cochrane).

Results

In total, 2032 patients were included (881 in the anakinra and 1151 in the control/standard care group); 69.1% of them were males. Overall, the mean difference from admission until last follow‐up in CRP values was −9.66, where notable reductions were seen in the anakinra group (SMD = −0.46, p < 0.00001, N = 655). Serum ferritin mean values were reduced by 1467.16 in the anakinra group (SMD = −0.31, p = 0.004, N = 537). D‐dimer mean values were largely reduced by 4.04 in the anakinra group (SMD = −0.38, p = 0.0004, N = 375).

Conclusion

This study finds that anakinra is potentially a strong candidate as an anti‐inflammatory agent to reduce mortality in COVID‐19 patients, specifically in patients with elevated inflammatory biomarkers.

Serum amyloid A forms stable oligomers that disrupt vesicles at lysosomal pH and contribute to the pathogenesis of reactive amyloidosis

Serum amyloid A (SAA) is an acute-phase plasma protein that functions in innate immunity and lipid homeostasis. SAA is a protein precursor of reactive AA amyloidosis, the major complication of chronic inflammation and one of the most common human systemic amyloid diseases worldwide. Most circulating SAA is protected from proteolysis and misfolding by binding to plasma high-density lipoproteins. However, unbound soluble SAA is intrinsically disordered and is either rapidly degraded or forms amyloid in a lysosome-initiated process. Although acidic pH promotes amyloid fibril formation by this and many other proteins, the molecular underpinnings are unclear. We used an array of spectroscopic, biochemical, and structural methods to uncover that at pH 3.5-4.5, murine SAA1 forms stable soluble oligomers that are maximally folded at pH 4.3 with ∼35% α-helix and are unusually resistant to proteolysis. In solution, these oligomers neither readily convert into mature fibrils nor bind lipid surfaces via their amphipathic α-helices in a manner typical of apolipoproteins. Rather, these oligomers undergo an α-helix to β-sheet conversion catalyzed by lipid vesicles and disrupt these vesicles, suggesting a membranolytic potential. Our results provide an explanation for the lysosomal origin of AA amyloidosis. They suggest that high structural stability and resistance to proteolysis of SAA oligomers at pH 3.5-4.5 help them escape lysosomal degradation, promote SAA accumulation in lysosomes, and ultimately damage cellular membranes and liberate intracellular amyloid. We posit that these soluble prefibrillar oligomers provide a missing link in our understanding of the development of AA amyloidosis.

Interleukin-6 and C-reactive protein load in pre-storage and post-storage white blood cell-filtered red blood cell transfusions in premature infants

OBJECTIVE

Leukocyte contamination during blood transfusion can cause many adverse effects. Filtration can be performed either at bedside during the transfusion or as pre-storage filtration. Pre-storage filtration is superior to bedside filtration because leukocytes are removed prior to storage, thus preventing further adverse effects associated with the storage of these cells.

METHODS AND MATERIALS

One hundred and six infants were randomised into two groups: pre-storage filtration (group 1, n = 53) and bedside filtration (group 2, n = 53). C-reactive protein (CRP) and interleukin-6 (IL-6) levels were analysed within 24 h prior to the transfusion and 24 h after completion of the transfusion.

RESULTS

In group 1, pre-transfusion median CRP and IL-6 levels were 2·95 (0·73-10·25) mg L(-1) and 8·59 (3·45-20·55) pg L(-1) , respectively, and post-transfusion median CRP and IL-6 levels were 2·28 (0·44-12·87) mg L(-1) and 6·62 (2·18-27·87) pg L(-1) , respectively. In group 2, pre-transfusion median CRP and IL-6 levels were 1·30 (0·40-7·84) mg L(-1) and 4·40 (2-17·12) pg L(-1) , respectively, and post-transfusion median CRP and IL-6 levels were 3·50 (0·50-7·85) mg L(-1) and 8·30 (3·48-23·75) pg L(-1) , respectively. There were no differences between pre-storage and post-storage leukoreduction average IL-6 and CRP levels in either group (P > 0·05 for both). Packed red blood cell (PRBC)-related necrotizing enterocolitis was detected in one infant in group 2.

CONCLUSIONS

Because leukocytes in PRBC transfusions can be associated with many undesirable effects, leukoreduction is the best choice to prevent those effects. However, this method is still controversial. We demonstrated that using pre-storage and post-storage leukoreduction methods in erythrocyte transfusions did not change CRP or IL-6 levels, which are indicators of acute-phase response.

Serum lipoprotein(a) concentrations do not change significantly in the immediate seven-day period post myocardial infarction

BACKGROUND

Lipoprotein(a) is an independent predictor of cardiovascular disease and its variability after myocardial infarction was assessed in this study.

METHODS

Lipoprotein(a) was analysed by a size insensitive latex immunoturbidimetric end point assay in samples from days 0 to 7 in 31 patients admitted with myocardial infarction.

RESULTS

Median lipoprotein(a) changed by -0.9%, -0.1% and 9.6% on days 1, 2-3 and 4-7, respectively, and was not statistically significant. Median total cholesterol reduced by 8.7%, 9.1%, 14.5% and C-reactive protein increased by 68.4%, 510%, 502% over days 1, 2-3, 4-7, respectively.

CONCLUSIONS

Unlike total cholesterol and C-reactive protein, lipoprotein(a) does not demonstrate significant variability for up to seven days after myocardial infarction and measurements made during this period after myocardial infarction are physiologically meaningful.