Serum ferritin/C-reactive protein ratio is a simple and effective biomarker for diagnosing iron deficiency in the context of systemic inflammation

BACKGROUND

Diagnosing iron deficiency is challenging in the presence of systemic inflammation.

AIM

To investigate the relationship between plasma C-reactive protein (CRP), serum ferritin (SF) and transferrin saturation (TS), with the objective of establishing a straightforward ratio applicable in the presence of inflammatory syndrome.

DESIGN

Test prospective cohort and validation retrospective cohort.

METHODS

A prospective cohort of inpatients (n = 140) assessed the correlation between CRP and SF/TS levels. The diagnostic performance of a determined ratio was evaluated for identifying iron deficiency (ID) using different definitions and in the presence of inflammation and/or chronic heart and/or kidney failure. A large validation cohort (n = 795) further assessed the predictive power of this ratio.

RESULTS

In a training cohort (median age 76 years [57-84]), a linear relation was observed between SF (µg/l) and CRP (mg/l), unlike with TS. The SF/CRP ratio accurately predicted ID, with receiver operating characteristic-area under the curve (ROC-AUC) values ranging from 0.85 to 0.92 for different ID definitions. A threshold of ≤6 demonstrated the highest Youden index (0.61). In the validation cohort (age 72 years [57-84]), the SF/CRP ratio exhibited an ROC-AUC of 0.88 [95% CI: 0.85-0.90], with an odds ratio of 37.9 [95% CI: 20.3-68.9] for the threshold of ≤6.

CONCLUSION

In this study, we demonstrated that the SF/CRP ratio, with a threshold of ≤6, is a simple and effective biomarker for ID, even in the presence of systemic inflammation or comorbidities. This ratio could potentially replace the complex set of criteria currently recommended by learned societies.

An immuno-lipidomic signature revealed by metabolomic and machine-learning approaches in labial salivary gland to diagnose primary Sjögren's syndrome

Introduction

Assessing labial salivary gland exocrinopathy is a cornerstone in primary Sjögren's syndrome. Currently this relies on the histopathologic diagnosis of focal lymphocytic sialadenitis and computing a focus score by counting lym=phocyte foci. However, those lesions represent advanced stages of primary Sjögren's syndrome, although earlier recognition of primary Sjögren's syndrome and its effective treatment could prevent irreversible damage to labial salivary gland. This study aimed at finding early biomarkers of primary Sjögren's syndrome in labial salivary gland combining metabolomics and machine-learning approaches.

Methods

We used a standardized targeted metabolomic approach involving high performance liquid chromatography coupled with mass spectrometry among newly diagnosed primary Sjögren's syndrome (n=40) and non- primary Sjögren's syndrome sicca (n=40) participants in a prospective cohort. A metabolic signature predictive of primary Sjögren's syndrome status was explored using linear (logistic regression with elastic-net regularization) and non-linear (random forests) machine learning architectures, after splitting the data set into training, validation, and test sets.

Results

Among 126 metabolites accurately measured, we identified a discriminant signature composed of six metabolites with robust performances (ROC-AUC = 0.86) for predicting primary Sjögren's syndrome status. This signature included the well-known immune-metabolite kynurenine and five phospholipids (LysoPC C28:0; PCaa C26:0; PCaaC30:2; PCae C30:1, and PCaeC30:2). It was split into two main components: the first including the phospholipids was related to the intensity of lymphocytic infiltrates in salivary glands, while the second represented by kynurenine was independently associated with the presence of anti-SSA antibodies in participant serum.

Conclusion

Our results reveal an immuno-lipidomic signature in labial salivary gland that accurately distinguishes early primary Sjögren's syndrome from other causes of sicca symptoms.

The relevance of pacing strategies in managing symptoms of post-COVID-19 syndrome

BACKGROUND

Post-COVID-19 syndrome (PCS) shares many features with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). PCS represents a major health issue worldwide because it severely impacts patients' work activities and their quality of life. In the absence of treatment for both conditions and given the beneficial effect of pacing strategies in ME/CFS, we conducted this study to assess the effectiveness of pacing in PCS patients.

METHODS

We retrospectively included patients meeting the World Health Organization definition of PCS who attended the Internal Medicine Department of Angers University Hospital, France between June 2020 and June 2022, and were followed up until December 2022. Pacing strategies were systematically proposed for all patients. Their medical records were reviewed and data related to baseline and follow-up assessments were collected. This included epidemiological characteristics, COVID-19 symptoms and associated conditions, fatigue features, perceived health status, employment activity, and the degree of pacing adherence assessed by the engagement in pacing subscale (EPS). Recovery was defined as the ability to return to work, and improvement was regarded as the reduction of the number and severity of symptoms.

RESULTS

A total of 86 patients were included and followed-up for a median time of 10 [6-13] months. Recovery and improvement rates were 33.7% and 23.3%, respectively. The EPS score was the only variable significantly associated with recovery on multivariate analysis (OR 40.43 [95% CI 6.22-262.6], p < 0.001). Patients who better adhered to pacing (high EPS scores) experienced significantly higher recovery and improvement rates (60-33.3% respectively) than those with low (5.5-5.5% respectively), or moderate (4.3-17.4% respectively) scores.

CONCLUSION

Our findings demonstrated that pacing is effective in the management of patients with PCS, and that high levels of adherence to pacing are associated with better outcomes.

Warning Signals of Post-Exertional Malaise in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Retrospective Analysis of 197 Patients

Post-exertional malaise (PEM), the key feature of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), is characterized by baseline symptom exacerbation after exposure to a stressor, and some patients can experience new or non-typical symptoms. We hypothesized that new or non-typical symptoms occurring long enough before onset of baseline symptom exacerbation could be warning signals predicting PEM. Adult ME/CFS patients who attended the internal medicine department of Angers University Hospital (France) between October 2011 and December 2019 were included in a retrospective medical records review. Patients who experienced one or more new or non-typical symptoms before baseline symptom exacerbation were compared with the rest of the study population for PEM features, epidemiological characteristics, fatigue features, and comorbidities. New or non-typical symptoms preceded baseline symptom exacerbation in 27/197 (13.7%) patients, and the most frequent ones were mood disorders (37%). When compared to the rest of the study population, only PEM intensity was significantly lower in these patients (p = 0.004), even after adjustment for sex and age at disease onset (p = 0.007). New or non-typical symptoms preceding baseline symptom exacerbation in some ME/CFS patients could be warning signals for PEM. Their identification could help preventing PEM occurrences or reducing their intensity leading to improving disease prognosis.

Evolution of plasma vitamin B12 in patients with solid cancers during curative versus supportive care

INTRODUCTION

The direction of the causal link between solid cancers and elevated plasma vitamin B₁₂ (B₁₂) remains uncertain.

METHODS

We retrospectively included patients having two B₁₂ measurements with a B₁₂ initially ≥ 1000 ng/l and a solid cancer diagnosed between the measurements. Patients were included in the Curative or Supportive group according to their treatments.

RESULTS

B₁₂ changes over time differed between groups (p = 0.001): +157.4 ng/l/month in the Supportive care group versus -171.6 ng/l/month in the Curative care group.

CONCLUSIONS

The decrease of plasma B₁₂ in cases of curative care could suggest that this B₁₂ elevation is secondary to solid cancers.

Association of Primary Sjögren's Syndrome and Vitamin B12 Deficiency: A Cross-Sectional Case-Control Study

Descriptive and retrospective studies without control groups have suggested a possible association between primary Sjögren's syndrome (pSS) and vitamin B12 (B12) deficiency. This is of importance because several mucosal and neurological features are common to these two conditions and could be prevented or reversed in case of B12 deficiency. We aimed to evaluate the association between pSS and B12 deficiency. We prospectively assessed the B12 status of 490 patients hospitalized in an internal medicine department over a 15-week period. Patients with pernicious anemia were excluded. We extracted patients with pSS and paired them with controls according to age and sex, with a 1:5 ratio. Twenty-one pSS patients were paired with 105 control patients. The median age was 70 years old (51-75) and 95.2% of patients were women. The plasma B12 level was lower in pSS patients (329 (293-521) ng/L vs. 456 (341-587) ng/L, p < 0.0001). B12 deficiency was associated with pSS (42.9% among pSS patients vs. 11.4% among controls), even after adjustment for other causes of B12 deficiency (OR 6.45 (95%CI: 2.08-20.0)). In conclusion, pSS appeared to be associated with B12 deficiency, even after the exclusion of pernicious anemia. This justifies screening and treating B12 deficiency in pSS patients.

Influence of the Type of Training Sport Practised on Psychological and Physiological Parameters during Exhausting Endurance Exercises

The present purpose was to study the influence of the type of training sport practised (long distance running, sprinting, handball) on ratings of perceived exertion (RPE), estimation of time limit (ETL), and heart rate (HR) on running tests. It was hypothesised that these parameters would be related to the type of training sport practised. 31 trained women (10 endurance-trained runners, 10 sprinters, and 11 handball players) performed two exercises to exhaustion on an outdoor track. The first test was a graded run to estimate maximal aerobic speed (SMA), i.e., the minimal speed which elicited maximal oxygen uptake. The second test was a constant all-out run at speed delta 50 (SΔ50), which corresponded to the speed halfway between SMA and the speed at lactate threshold (SLT), to specify time to exhaustion at this intensity (TLIM). Sensations regarding RPE, ETL, and HR were recorded during these tests. SMA, SΔ50, and SLT, expressed in absolute values (km · hr.−1) were statistically significantly different between groups ( p<.05) whereas TLIM was not. The covariance analysis showed that endurance-trained runners perceived the exercise as lighter and presented lower HR than handball players and sprinters for a same running %SMA ( p<.05). Moreover, endurance-trained runners felt that they could endure more than the other groups at a given %SMA or relative exhaustion time (%TLIM). These results mean that the type of training sport which has been performed may mediate perceptual responses and influence physiological parameters during exhausting exercises. These results are likely in part related to sport-specificity of the exercise mode used in tests. This point must be taken into consideration by physical trainers who have to prescribe exercise intensities during athletic seasons for different groups of athletes.

Diurnal variations in insulin secretion and K+ permeability in isolated rat islets

1. The effects of glucose on insulin secretion and 86Rb efflux from isolated rat islets were studied at six different times during a 24-h period (00.00, 04.00, 08.00, 12.00, 16.00 and 20.00 h). 2. In the absence of glucose and in the presence of substimulatory concentrations (2.8 mmol/L) of the sugar, insulin secretion did not vary with the time of day. At a glucose concentration of 5.6 mmol/L the stimulated insulin secretion was greater than basal levels only at 20.00 h. 3. At a higher sugar concentration (8.3 mmol/L) the increase in insulin secretion and the reduction in 86Rb efflux rate were more marked during the dark period. No effect of the time of day on insulin secretion was observed at glucose concentrations above 8.3 mmol/L (except in 27.7 mmol/L). 4. The time of day appears to affect insulin secretion mainly at glucose concentrations close to physiological values (5.6-8.3 mmol/L). 5. This result agrees with the ability of physiological amounts of glucose to alter the 86Rb-permeability of pancreatic B cells at the same time intervals.

Effect of chemical stimulation of the dorsomedial hypothalamic nucleus on blood plasma glucose, triglycerides and free fatty acids in rats

The effects of chemical stimulation of the dorsomedial hypothalamic nucleus (DMH) on blood plasma concentration of glucose, triglycerides, insulin, and free fatty acids (FFA) were investigated in anesthetized adult Wistar rats. Microinjection of 12.5 nmol of norepinephrine into the DMH increased blood plasma concentration of glucose and FFA, decreased triglycerides, and did not change plasma insulin within 5 min; after 20 min, blood glucose and FFA reached control values. Microinjection of epinephrine (12.5 nmol) into the DMH also increased blood plasma glucose concentration and decreased triglycerides after 5 min. These effects are probably mediated by beta-adrenergic mechanisms, because they were prevented by beta-adrenergic antagonist propranolol, but not by alpha-adrenergic antagonist prazosin. Microinjection into the DMH of glutamate, dopamine, or acetylcholine failed to cause any change in those metabolic parameters, corroborating the hypothesis that the DMH is part of a beta-adrenergic pathway involved in short-term modulation of the availability of glucose and FFA.

Prolactin induces maturation of glucose sensing mechanisms in cultured neonatal rat islets

The effects of PRL treatment on insulin content and secretion, and 86Rb and 45Ca fluxes from neonatal rat islets maintained in culture for 7-9 days were studied. PRL treatment enhanced islet insulin content by 40% and enhanced early insulin secretion evoked by 16.7 mM glucose. Insulin release stimulated by oxotremorine-M, a muscarinic agonist, in the presence of glucose (8.3 or 16.7 mM) was unchanged by PRL treatment. However, PRL treatment potentiated phorbol 12,13-dibutyrate-stimulated insulin secretion in the presence of the above glucose concentrations. PRL treatment potentiated the reduction in 86Rb efflux induced by glucose or tolbutamide and enhanced the increase in 86Rb efflux evoked by diazoxide. PRL treatment slightly potentiated the increment in 45Ca uptake induced by high concentrations of K+, but failed to affect the increment evoked by 16.7 mM glucose. Since glucose-induced 45Ca uptake was not affected by PRL, we suggest that the enhancement in first phase insulin secretion evoked by glucose in the PRL-treated islets occurs at a step in the secretory process that may involve protein kinase-C. These data further support observations that PRL treatment increases islet sensitivity to glucose.

Cation transport by pancreatic beta-cells: effect of 4-aminopyridine on 86Rb+ and 45Ca2+ fluxes

The effects of 4-aminopyridine (4-AP) on insulin release, glucose oxidation and 86Rb+ and 45Ca2+ fluxes of rat isolated islets were studied. 4-AP (0.1 and 1.0 mM) did not alter the 86Rb+ fractional efflux. However, 10 mM 4-AP significantly increased the 86Rb+ fractional efflux. 10 mM 4-AP also reduced the insulin release from islets incubated over 90 min in the presence of both 6 and 16.7 mM glucose and from perifused islet in the presence of 16.7 mM glucose. 4-AP (10 mM) only transiently increased the insulin release and the 45Ca2+ fractional efflux in the presence of 6 mM glucose. The 45Ca2+ fractional efflux was not changed when the islets were perifused at higher glucose concentration. At zero, 6 or 16.7 mM glucose, 4-AP (10 mM) significantly increased the 45Ca2+ net uptake by islets incubated for 90 min. 10 mM 4-AP significantly reduced the glucose oxidation of islets incubated for 120 min in the presence of 16.7 mM glucose. The effects of 10 mM 4-AP on the dynamics of insulin release and 86Rb+ fractional efflux were poorly reversible. In conclusion, 4-AP, at concentrations that did not alter the glucose metabolism, (0.1 and 1 mM), failed to affect the K+ permeability in beta-cells as judged by the measurements of 86Rb+ fractional efflux. At higher concentrations (10 mM) 4-AP increased 86Rb+ efflux, decreased glucose metabolism and reduced insulin release.

The mechanism of gentamicin-inhibited insulin release by isolated islets

These experiments were performed in order to determine the mechanism of action of the aminoglycoside antibiotic gentamicin on insulin release by isolated islets. Gentamicin significantly reduced the insulin release in the absence as well as in the presence of increasing concentrations of glucose. This effect was immediate and promptly reversible. In the presence of glucose plus high concentrations of K+ the antibiotic did not affect insulin secretion. Gentamicin did not change 86Rb efflux from perifused islets or the glucose metabolism in incubated islets. These data show that gentamicin does not alter the recognition and subsequent metabolism of glucose, and the system responsible for insulin secretion. We suggest that gentamicin reduces glucose-induced insulin release by blocking the entry of Ca2+ into the B-cells.