Challenges of Rheumatoid Arthritis Management in Sub-Saharan Africa in the 21st Century

In recent decades, several advances have been made in the management of rheumatoid arthritis (RA) both in the diagnostic field and in the therapeutic field. Unfortunately, RA remains poorly studied in black Africa. Epidemiological data are rare and controversial. The estimated prevalence of RA in Africa is about 0% - 2.54%. Risk factors associated with RA must be studied by taking into account special features of black Africa such as the low tobacco consumption in certain regions, the tropical climate and the high frequency of endemic parasitic and viral infections. The initially supposed mildness of RA in black Africa is increasingly challenged. The diagnosis is often made too late because of the scarcity of rheumatologists and ignorance. Diagnostic tools are limited to the clinical data, the erythrocyte sedimentation rate and radiographs as the other tools are poorly available. In addition, there are misconceptions in African communities, responsible for loss of sight during follow-up and treatment discontinuations. This is exacerbated by the shortage of disease-modifying anti-rheumatic drugs (DMARDs) and the inability to afford them. Furthermore, biological agents are very difficult to access. Further studies are essential to better understand the characteristics of RA in black Africa. Thus, collaborations between African and Western research teams seem very important. In order to make available the DMARDs especially biological agents, pharmaceutical companies can contribute through research partnerships. Moreover, governments should provide a better place for chronic inflammatory diseases in the programs against non-communicable diseases. Finally, training must also be promoted to increase the number of specialists and the level of knowledge of other health workers.

Celiac disease serology in patients with different pretest probabilities: Is biopsy avoidable?

AIM: To establish the diagnostic performance of sev-eral serological tests, individually and in combination, for diagnosing celiac disease (CD) in patients with different pretest probabilities, and to explore potential se- rological algorithms to reduce the necessity for biopsy. METHODS: We prospectively performed duodenal biopsy and serology in 679 adults who had either high risk (n = 161) or low risk (n = 518) for CD. Blood samples were tested using six assays (enzyme-linked immunosorbent assay) that detected antibodies to tissue transglutaminase (tTG) and deamidated gliadin peptide (DGP). RESULTS: CD prevalence was 39.1% in the high-risk population and 3.3% in the low-risk group. In high-risk patients, all individual assays had a high diagnostic efficacy [area under receiving operator characteristic curves (AU ROC): 0.968 to 0.999]. In contrast, assays had a lower diagnostic efficacy (AU ROC: 0.835 to 0.972) in the low-risk group. Using assay combinations, it would be possible to reach or rule out diagnosis of CD without biopsy in 92% of cases in both pretest populations. We observed that the new DGP/tTG Screen assay resulted in a surplus compared to more conventional assays in any clinical situation. CONCLUSION: The DGP/tTG Screen assay could be considered as the best initial test for CD. Combinations of two tests, including a DGP/tTG Screen, might be able to diagnose CD accurately in different clinical scenarios making biopsy avoidable in a high proportion of subjects.

Non-invasive prediction of persistent villous atrophy in celiac disease

BACKGROUND Celiac disease(CD)is an immune-mediated enteropathy that is primarily treated with a gluten-free diet(GFD).Mucosal healing is the main target of the therapy.Currently,duodenal biopsy is the only way to evaluate mucosal healing,and noninvasive markers are challenging.Persistent elevation of anti-tissue transglutaminase antibodies(aTTG)is not an ideal predictor of persistent villous atrophy(VA).Data regarding prediction of atrophy using anti-deamidated gliadin peptide antibodies(aDGP)and abdominal ultrasonography are lacking.AIM To evaluate the ability of aTTG,aDGP,small bowel ultrasonography,and clinical and laboratory parameters in predicting persistent VA determined using histology.METHODS Patients with CD at least 1 year on a GFD and available follow-up duodenal biopsy,levels of aTTG and aDGP,and underwent small bowel ultrasonography were included in this retrospective cohort study.We evaluated the sensitivity,specificity,and positive and negative predictive values of aTTG,aDGP,small bowel ultrasonography,laboratory and clinical parameters to predict persistent VA.A receiver operating characteristic(ROC)curve analysis of antibody levels was used to calculate cut off values with the highest accuracy for atrophy prediction.RESULTS Complete data were available for 82 patients who were followed up over a period of four years(2014-2018).Among patients included in the analysis,women(67,81.7%)were predominant and the mean age at diagnosis was 33.8 years.Followup biopsy revealed persistent VA in 19 patients(23.2%).The sensitivity and specificity of aTTG using the manufacturer’s diagnostic cutoff value to predict atrophy was 50%and 85.7%,respectively,while the sensitivity and specificity of aDGP(using the diagnostic cutoff value)was 77.8%and 75%,respectively.Calculation of an optimal cutoff value using ROC analysis(13.4 U/mL for aTTG IgA and 22.6 U/mL for aDGP IgA)increased the accuracy and reached 72.2%[95%confidence interval(CI):46.5-90.3]sensitivity and 90%(95%CI:79.5-96.2)specificity for aDGP IgA and 66.7%(95%CI:41.0-86.7)sensitivity and 93.7%(95%CI:84.5-98.2)specificity for aTTG IgA.The sensitivity and specificity of small bowel ultrasonography was 64.7%and 73.5%,respectively.A combination of serology with ultrasound imaging to predict persistent atrophy increased the positive predictive value and specificity to 88.9%and 98%for aTTG IgA and to 90.0%and 97.8%for aDGP IgA.Laboratory and clinical parameters had poor predictive values.CONCLUSION The sensitivity,specificity,and negative predictive value of aTTG and aDGP for predicting persistent VA improved by calculating the best cutoff values.The combination of serology and experienced bowel ultrasound examination may achieve better accuracy for the detection of atrophy.

Assessment of the Bemisia tabaci C YP6CM l vQ transcript and protein levels in laboratory and field-derived imidacloprid-resistant insects and cross-metabolism potential of the recombinant enzyme

Over-expression of the cytochrome P450 CYP6CM1 gene has been associated with imidacloprid resistance in a number of Q and B biotype Bemisia tabaci laboratory strains from distinct geographical origins worldwide. We recently demonstrated that the Q biotype version of the CYP6CM 1 protein （CYP6CMlvQ） is capable of metabolizing imida- cloprid. Here, we show that the levels of BtCYP6CMlvQ were also elevated in laboratory- resistant strains and field-derived populations, with variable imidacloprid resistance levels, collected in Crete. High levels of CYP6CMlvQ transcripts were also determined in survivors of a heterogeneous field population, after exposure to discriminating imidacloprid dosage. Using peptide antibody-based detection assays, we demonstrated that in line with transcriptional data, the CYP6CMlvQ protein levels were higher in imidacloprid-resistant insects, which further implicates the gene as the causal factor of resistance. Finally, assess- ment of the cross-metabolism potential of CYP6CMlvQ against additional neonicotinoid molecules used for B. tabaci control revealed that clothianidin and thiacloprid, but not acetamiprid or thiamethoxam, are metabolized by the recombinant enzyme in vitro.