Mesenchymal stromal cells for improvement of cardiac function following acute myocardial infarction: a matter of timing.

Acute myocardial infarction (AMI) is the leading cause of cardiovascular death and remains the most common cause of heart failure. Reopening of the occluded artery, i.e., reperfusion, is the only way to save the myocardium. However, the expected benefits of reducing infarct size are disappointing due to the reperfusion paradox, which also induces specific cell death. These ischemia-reperfusion (I/R) lesions can account for up to 50% of final infarct size, a major determinant for both mortality and the risk of heart failure (morbidity). In this review, we provide a detailed description of the cell death and inflammation mechanisms as features of I/R injury and cardioprotective strategies such as ischemic postconditioning as well as their underlying mechanisms. Due to their biological properties, the use of mesenchymal stromal/stem cells (MSCs) has been considered a potential therapeutic approach in AMI. Despite promising results and evidence of safety in preclinical studies using MSCs, the effects reported in clinical trials are not conclusive and even inconsistent. These discrepancies were attributed to many parameters such as donor age, in vitro culture, and storage time as well as injection time window after AMI, which alter MSC therapeutic properties. In the context of AMI, future directions will be to generate MSCs with enhanced properties to limit cell death in myocardial tissue and thereby reduce infarct size and improve the healing phase to increase postinfarct myocardial performance.

Ribosomal Proteins Regulate MHC Class I Peptide Generation for Immunosurveillance.

The MHC class I antigen presentation system enables T cell immunosurveillance of cancers and viruses. A substantial fraction of the immunopeptidome derives from rapidly degraded nascent polypeptides (DRiPs). By knocking down each of the 80 ribosomal proteins, we identified proteins that modulate peptide generation without altering source protein expression. We show that 60S ribosomal proteins L6 (RPL6) and RPL28, which are adjacent on the ribosome, play opposite roles in generating an influenza A virus-encoded peptide. Depleting RPL6 decreases ubiquitin-dependent peptide presentation, whereas depleting RPL28 increases ubiquitin-dependent and -independent peptide presentation. 40S ribosomal protein S28 (RPS28) knockdown increases total peptide supply in uninfected cells by increasing DRiP synthesis from non-canonical translation of "untranslated" regions and non-AUG start codons and sensitizes tumor cells for T cell targeting. Our findings raise the possibility of modulating immunosurveillance by pharmaceutical targeting ribosomes.

Optimal sampling strategies for darunavir and external validation of the underlying population pharmacokinetic model.

PURPOSE: A variety of diagnostic methods are available to validate the performance of population pharmacokinetic models. Internal validation, which applies these methods to the model building dataset and to additional data generated through Monte Carlo simulations, is often sufficient, but external validation, which requires a new dataset, is considered a more rigorous approach, especially if the model is to be used for predictive purposes. Our first objective was to validate a previously published population pharmacokinetic model of darunavir, an HIV protease inhibitor boosted with ritonavir or cobicistat. Our second objective was to use this model to derive optimal sampling strategies that maximize the amount of information collected with as few pharmacokinetic samples as possible. METHODS: A validation dataset comprising 164 sparsely sampled individuals using ritonavir-boosted darunavir was used for validation. Standard plots of predictions and residuals, NPDE, visual predictive check, and bootstrapping were applied to both the validation set and the combined learning/validation set in NONMEM to assess model performance. D-optimal designs for darunavir were then calculated in PopED and further evaluated in NONMEM through simulations. RESULTS: External validation confirmed model robustness and accuracy in most scenarios but also highlighted several limitations. The best one-, two-, and three-point sampling strategies were determined to be pre-dose (0 h); 0 and 4 h; and 1, 4, and 19 h, respectively. A combination of samples at 0, 1, and 4 h was comparable to the optimal three-point strategy. These could be used to reliably estimate individual pharmacokinetic parameters, although with fewer samples, precision decreased and the number of outliers increased significantly. CONCLUSIONS: Optimal sampling strategies derived from this model could be used in clinical practice to enhance therapeutic drug monitoring or to conduct additional pharmacokinetic studies.

Emerging Role of Eukaryote Ribosomes in Translational Control.

Translation is one of the final steps that regulate gene expression. The ribosome is the effector of translation through to its role in mRNA decoding and protein synthesis. Many mechanisms have been extensively described accounting for translational regulation. However it emerged only recently that ribosomes themselves could contribute to this regulation. Indeed, though it is well-known that the translational efficiency of the cell is linked to ribosome abundance, studies recently demonstrated that the composition of the ribosome could alter translation of specific mRNAs. Evidences suggest that according to the status, environment, development, or pathological conditions, cells produce different populations of ribosomes which differ in their ribosomal protein and/or RNA composition. Those observations gave rise to the concept of "specialized ribosomes", which proposes that a unique ribosome composition determines the translational activity of this ribosome. The current review will present how technological advances have participated in the emergence of this concept, and to which extent the literature sustains this concept today.

Neuroanatomical distribution and function of the vasopressin V1B receptor in the rat brain deciphered using specific fluorescent ligands.

It is now accepted that vasopressin, through V1A/V1B receptors, centrally regulates cognitive functions such as memory, affiliation, stress, fear and depression. However, the respective roles of these receptor isoforms and their contribution to stress-related pathologies remain uncertain. The development of new therapeutic treatments requires a precise knowledge of the distribution of these receptors within the brain, which has been so far hampered by the lack of selective V1B markers. In the present study, we have determined the pharmacological properties of three new potent rat V1B fluorescent ligands and demonstrated that they constitute valuable tools for simultaneous visualization and activation of native V1B receptors in living rat brain tissue. Thus, d[Leu4,Lys-Alexa 647)8]VP (analogue 3), the compound with the best affinity-selectivity/fluorescence ratio for the V1B receptor emerged as the most promising. The rat brain regions most concerned by stress such as hippocampus, olfactory bulbs, cortex and amygdala display the highest V1B fluorescent labelling with analogue 3. In the hippocampus CA2, V1B receptors are located on glutamatergic, not GABAergic neurones, and are absent from astrocytes. Using AVP-EGFP rats, we demonstrate the presence of V1B autoreceptors on AVP-secreting neurones not only in the hypothalamus, but also sparsely in the hippocampus. Finally, using both electrophysiology and visualization of ERK phosphorylation, we show analogue 3-induced activation of the V1B receptor in situ. This will help to analyse expression and functionality of V1B receptors in the brain and contribute to further explore the AVPergic circuitry in normal and pathological conditions.

BRCA1 affects protein phosphatase 6 signalling through its interaction with ANKRD28.

The tumour suppressor BRCA1 (breast and ovarian cancer-susceptibility gene 1) is implicated in several nuclear processes including DNA repair, transcription regulation and chromatin remodelling. BRCA1 also has some cytoplasmic functions including a pro-apoptotic activity. We identified ANKRD28 (ankyrin repeat domain 28) as a novel BRCA1-interacting protein in a yeast two-hybrid screen and confirmed this interaction by reciprocal immunoprecipitations of the two overexpressed proteins. Endogenous interaction between BRCA1 and ANKRD28 was also observed by co-immunoprecipitation and located in the cytoplasm by proximity ligation assay. The main site of interaction of ANKRD28 on BRCA1 is located in its intrinsically disordered scaffold central region. Whereas ANKRD28 silencing results in a destabilization of IκBε (inhibitor of nuclear factor κBε) through its activation of PP6 (protein phosphatase 6) co-regulator upon TNFα (tumour necrosis factor α) stimulation, BRCA1 overexpression stabilizes IκBε. A truncated form of BRCA1 that does not interact with ANKRD28 has no such effect. Our findings suggest that BRCA1 is a novel modulator of PP6 signalling via its interaction with ANKRD28. This new cytoplasmic process might participate in BRCA1 tumour-suppressor function.

Prospective, Split-Face, Randomized, Long-Term Blinded Objective Comparison of the Performance and Tolerability of Two New Hyaluronic Acid Fillers.

BACKGROUND: There are requirements for long-term, objective comparisons of hyaluronic acid (HA) dermal fillers. OBJECTIVE: To compare efficacy and tolerability of ART FILLER Universal (AFU) and ART FILLER Fine lines (AFFL) with the existing HA fillers for the treatment of nasolabial folds and crow's feet. MATERIALS AND METHODS: Prospective, randomized, rater- and patient-blind, split-face comparison of AFU with JUVEDERM Ultra 3 (JUV) and AFFL with FIRST LINES PureSense (FLPS). The severity of nasolabial folds and crow's feet was assessed by independent blinded evaluators using the Lemperle scale at baseline, day (D) 30/D45, D90, and D180. Tolerability, Global Aesthetic Improvement Scale (GAIS), wrinkle volumes, and skin thickness and density were also measured at D30/D45, D90, and D180. RESULTS: At D30 and D180 respectively, 61 and 57 patients were assessed. Scores for nasolabial folds and crow's feet showed statistically significant improvements at D30, D90, and D180. AFU and AFFL were noninferior to JUV and FLPS, respectively. Most patients showed GAIS improvements, maintained until at least D180 and significant increases of collagen synthesis in crow's feet and nasolabial folds. Treatments were well tolerated. CONCLUSION: AFU and AFFL are noninferior to comparators. The methodology used represents a novel approach to augment existing clinical assessment of HA fillers.

Quantifying Depth of Injection of Hyaluronic Acid in the Dermis: Data from Clinical, Laboratory, and Ultrasound Settings.

Although manufacturers' instructions for use of dermal fillers ordinarily direct injection in the superficial, mid or deep dermis, or, in some cases, the hypodermis (subcutis), the precise depth of injection may not always be for injectors. In this article, investigators report findings gathered from histopathology, ultrasound, "live" one on one training injections, as well as application of a mathematical formula for depth calculation of the various layers within the dermis. Areas of particular interest are the superficial reticular dermis and the mid dermis. Following the depth measurements detailed by Della Volpe et al in 2012, investigators compare and contrast their own depth findings of the various layers, arriving at the conclusion that the depth of the dermis is not as deep as had been previously assumed. The investigators also develop an argument for the appropriate angles of injection for placement of dermal filler into the various layers, demonstrating that the heretofore widely used angles of 30˚ and 45˚ are far more acute than required.

Belgian 2024 guidance on the use of pre-exposure prophylaxis.

OBJECTIVES: We aimed to develop a guidance on the use of pre-exposure prophylaxis (PrEP) for HIV tailored to the Belgian context. METHODS: Different aspects of PrEP care were judged by an expert group of nine Belgian clinicians, seeking consensus for areas of controversies. RESULTS: PrEP should be considered in HIV negative patients at high risk of acquiring HIV. Currently, only oral tenofovir/emtricitabine is available in Belgium for PrEP, which can be used daily, or also event-driven in cisgender men and trans women who are not taking exogenous estradiol-based hormones. Personal counselling directed at medication adherence and sexual health should have a central role in PrEP care. At the initial assessment clinicians should give attention to symptoms of an acute HIV infection, the patients' immunization status and renal function. A regular follow-up must be set up to diagnose HIV seroconversion, treat sexually transmitted infections, and manage side effects of PrEP. CONCLUSION: The Belgian guidance on the use of PrEP provides a point of reference for standard PrEP care in Belgium and will be periodically updated.

Understanding adaptive responses in PrEP service delivery in Belgian HIV clinics: a multiple case study using an implementation science framework.

INTRODUCTION: In Belgium, oral HIV pre-exposure prophylaxis (PrEP) is primarily provided in specialized clinical settings. Optimal implementation of PrEP services can help to substantially reduce HIV transmission. However, insights into implementation processes, and their complex interactions with local context, are limited. This study examined factors that influence providers' adaptive responses in the implementation of PrEP services in Belgian HIV clinics. METHODS: We conducted a qualitative multiple case study on PrEP care implementation in eight HIV clinics. Thirty-six semi-structured interviews were conducted between January 2021 and May 2022 with a purposive sample of PrEP care providers (e.g. physicians, nurses, psychologists), supplemented by 50 hours of observations of healthcare settings and clinical interactions. Field notes from observations and verbatim interview transcripts were thematically analysed guided by a refined iteration of extended Normalisation Process Theory. RESULTS: Implementing PrEP care in a centralized service delivery system required considerable adaptive capacity of providers to balance the increasing workload with an adequate response to PrEP users' individual care needs. As a result, clinic structures were re-organized to allow for more efficient PrEP care processes, compatible with other clinic-level priorities. Providers adapted clinical and policy norms on PrEP care (e.g. related to PrEP prescribing practices and which providers can deliver PrEP services), to flexibly tailor care to individual clients' situations. Interprofessional relationships were reconfigured in line with organizational and clinical adaptations; these included task-shifting from physicians to nurses, leading them to become increasingly trained and specialized in PrEP care. As nurse involvement grew, they adopted a crucial role in responding to PrEP users' non-medical needs (e.g. providing psychosocial support). Moreover, clinicians' growing collaboration with sexologists and psychologists, and interactions with PrEP users' family physician, became crucial in addressing complex psychosocial needs of PrEP clients, while also alleviating the burden of care on busy HIV clinics. CONCLUSIONS: Our study in Belgian HIV clinics reveals that the implementation of PrEP care presents a complex-multifaceted-undertaking that requires substantial adaptive work to ensure seamless integration within existing health services. To optimize integration in different settings, policies and guidelines governing PrEP care implementation should allow for sufficient flexibility and tailoring according to respective local health systems.

Evaluation of the effectiveness of nurse coaching in improving health outcomes in chronic conditions.

Nurse coaching is gaining acceptance as a legitimate, holistic enhancement to Western medicine. Thirteen research studies that looked at nurse coaching interventions in patients with various chronic conditions were reviewed and the outcomes discussed. All but 2 of these studies reported at least some statistically significant positive health outcomes.

Heart rate reduction after genetic ablation of L-type Cav1.3 channels induces cardioprotection against ischemia-reperfusion injury.

Background: Acute myocardial infarction (AMI) is the major cause of cardiovascular mortality worldwide. Most ischemic episodes are triggered by an increase in heart rate, which induces an imbalance between myocardial oxygen delivery and consumption. Developing drugs that selectively reduce heart rate by inhibiting ion channels involved in heart rate control could provide more clinical benefits. The Cav1.3-mediated L-type Ca2+ current (ICav1.3) play important roles in the generation of heart rate. Therefore, they can constitute relevant targets for selective control of heart rate and cardioprotection during AMI. Objective: We aimed to investigate the relationship between heart rate and infarct size using mouse strains knockout for Cav1.3 (Cav1.3-/-) L-type calcium channel and of the cardiac G protein gated potassium channel (Girk4-/-) in association with the funny (f)-channel inhibitor ivabradine. Methods: Wild-type (WT), Cav1.3+/-, Cav1.3-/- and Girk4-/- mice were used as models of respectively normal heart rate, moderate heart rate reduction, bradycardia, and mild tachycardia, respectively. Mice underwent a surgical protocol of myocardial IR (40 min ischemia and 60 min reperfusion). Heart rate was recorded by one-lead surface ECG recording, and infarct size measured by triphenyl tetrazolium chloride staining. In addition, Cav1.3-/- and WT hearts perfused on a Langendorff system were subjected to the same ischemia-reperfusion protocol ex vivo, without or with atrial pacing, and the coronary flow was recorded. Results: Cav1.3-/- mice presented reduced infarct size (-29%), while Girk4-/- displayed increased infarct size (+30%) compared to WT mice. Consistently, heart rate reduction in Cav1.3+/- or by the f-channel blocker ivabradine was associated with significant decrease in infarct size (-27% and -32%, respectively) in comparison to WT mice. Conclusion: Our results show that decreasing heart rate allows to protect the myocardium against IR injury in vivo and reveal a close relationship between basal heart rate and IR injury. In addition, this study suggests that targeting Cav1.3 channels could constitute a relevant target for reducing infarct size, since maximal heart rate dependent cardioprotective effect is already observed in Cav1.3+/- mice.

Long-Term Efficacy and Tolerability of a Medium G' HA Filler with Tri-Hyal Technology on the Rejuvenation of the Mobile Facial Zone.

Purpose: Injectable hyaluronic acid-based fillers are commonly used for the correction of skin contour irregularities and to smooth skin depressions formed by volume loss during the aging process. These fillers are particularly efficient to restore perioral skin depressions/wrinkles or to correct topographical anomalies. The European directives require a continuous evaluation of the performance of these medical devices, particularly for CE marked products. Methods: An 18-month prospective randomized single-blind study for the efficacy and safety of ART FILLER Universal (AFU) was performed on the lips, the nasolabial folds, and the marionettes lines. The evaluations were performed on 153 subjects enrolled in this study. The efficacy, the longevity, and the safety were evaluated for the injected areas via area specific clinical scoring after a single injection with the filler and with no re-touch. Results: We showed here that filler injection induced potent improvements of volume restoration after a single injection on all the treated areas. These beneficial properties of the filler were significant 3 weeks after injection and during the whole study period. Moreover, injections of the filler were well tolerated by the subjects. The recorded adverse events are routinely seen with HA fillers for face volume corrections, and most of these local reactions resolved within 14 days. Conclusion: AFU was well tolerated and showed a continuous efficacy for at least 18 months, in exploratory analyses.

Long-term efficacy and safety of a hyaluronic acid dermal filler based on Tri-Hyal technology on restoration of midface volume.

INTRODUCTION: Art Filler Volume (AFV) is a hyaluronic acid (HA)-based filler formulated with "Tri-Hyal" technology, a unique combination of three sizes of HA chains. This study assessed AFV efficacy and safety over 18 months when used to restore midface volume. METHODS: During this open-label study, a maximum of 1.8 mL AFV was injected into each cheek area on Day 0 (D0). Subjects were evaluated at D21, when, if necessary, a retouch could be performed (maximum 1.2 mL per cheek). Subjects were evaluated at seven follow-up visits through to D540. The primary assessment was based on the evolution of the Medicis Midface Volume Scale (MMVS) grade on D21. Secondary outcomes were local and general adverse events, investigator- and subject-assessed Global Aesthetic Improvement Scale scores and changes in self-esteem. RESULTS: Of the 79 healthy Caucasians enrolled (mean age 54.8 years), 25 required a second injection. In the intention-to-treat population, mean overall MMVS scores improved significantly from D0 (3.2 ± 0.4) to D21 (1.8 ± 0.6) and D42 (1.7 ± 0.6) (all p < 0.0001). MMVS scores for each cheek also improved significantly, irrespective of retouch on D21: 22% of injections showed a persistent benefit at D540 without retouch. The most common adverse events were pain on palpation (19%), erythema (15%) and edema (13%); most were mild or moderate and resolved within 2 weeks. CONCLUSION: AFV produces a sustained objective and subjective midface volume restoration in female and male subjects, often without retouching, and was well tolerated.

A prospective multicenter clinical trial evaluating the efficacy and safety of a hyaluronic acid-based filler with Tri-Hyal technology in the treatment of lips and the perioral area.

BACKGROUND: Age-related changes of facial soft tissue cause clinical signs of facial aging such as lip atrophy, marionette lines, and an accentuated nasolabial fold. These changes can be modified using dermal fillers. AIMS: To evaluate efficacy, longevity, and safety of a cross-linked hyaluronic acid-based filler with Tri-Hyal technology in the treatment of lips, nasolabial folds, and marionette lines. MATERIALS AND METHODS: This prospective, multi-center trial evaluated injections of three different areas (lips, nasolabial fold alone, or with marionette wrinkles) with a soft tissue filler containing 25 mg/ml cross-linked hyaluronic acid and 0.3% lidocaine. Primary endpoint was the aesthetic correction 3 weeks after one injection session without touch-up. Follow-up was 18 months. Assessments were performed using the Global Aesthetic Score (GAS), clinical scoring based on photographic scales, high-frequency ultrasound imaging, and the Global Aesthetic Improvement Scale (GAIS). RESULTS: In total, 100 subjects were injected. GAS improved significantly for all treatment indications at 3 weeks (p < 0.0001). Success rates were highest for nasolabial folds (98.4%), followed by marionette lines (94.4%) and lips (73.5%). After 18 months post-injection, success was observed in 91%, 88%, and 33% of subjects injected into nasolabial folds, marionette lines, and lips, respectively. GAIS scored highest for nasolabial folds (SGAIS: 71%; IGAIS: 40%), followed by marionette lines (SGAIS: 56%; IGAIS: 33%) and lips (SGAIS: 30%; IGAIS: 22%) at 18 months follow-up. CONCLUSIONS: The filler demonstrated high efficacy and safety in all indications. Regional differences in longevity were evident. Thus, the necessity of regional retreatments should be discussed with patients before injection.

Cell cycle-dependent conjugation of endogenous BRCA1 protein with SUMO-2/3.

BACKGROUND: BRCA1, the main breast and ovarian cancer susceptibility gene, has a key role in maintenance of genome stability, cell cycle and transcription regulation. Interestingly, some of the numerous proteins which interact with BRCA1 protein undergo conjugation with small ubiquitin-like modifiers (SUMO). This post-translational modification is related to transcription, DNA repair, nuclear transport, signal transduction, and to cell cycle stress response. METHODS AND RESULTS: Protein sequence analysis suggests that sumoylation target sites belong to the RING finger and BRCT domains (BRCA1 C-terminus), two crucial regions for BRCA1 function. Moreover putative SUMO interacting motifs are present in the sequence of many proteins of BRCA1 network. Using immunoprecipitations and western blotting, we show the conjugation of endogenous nuclear BRCA1 protein with SUMO-2/3. BRCA1 conjugation with SUMO-2/3 is linked to the cell cycle in a cell line dependent manner since no cell cycle dependence of sumoylation is observed in MCF7 breast cancer cells. In contrast, BRCA1 conjugation with SUMO-2/3 is linked to the oxidative stress independently to the cell line, in DU145, MCF7 and 293 T cells. CONCLUSION AND GENERAL SIGNIFICANCE: Our data reveal a new BRCA1 regulation pathway implying sumoylation in response to cell cycle progression and oxidative stress, providing a possible mechanism for the involvement of BRCA1 gene in tumorigenesis.

Delayed postconditioning in the mouse heart in vivo.

BACKGROUND: Reperfusion during acute myocardial infarction remains the best treatment for reducing infarct size. Postconditioning, applied at the onset of reperfusion, reduces myocardial infarction both in animals and humans. The objective of this study was to identify the time delay to apply postconditioning at reperfusion, allowing preservation of cardioprotection in the mouse myocardium. This is a major issue in the management of acute myocardial infarction patients. METHODS AND RESULTS: Mice were subjected to 40 minutes of ischemia and 60 minutes of reperfusion (IR(60')). Postconditioning protocols corresponding to repetitive ischemia (3 cycles of 1 minute of ischemia and 1 minute of reperfusion) were applied during early reperfusion at various time durations (Δt) after reopening of the coronary artery (Δt=10 seconds, 1, 5, 10, 15, 20, 30, and 45 minutes; PostC(Δt)). Infarct size/area at risk was reduced by 71% in PostC(Δ1) compared with IR(60') mice (P=5×10(-6)). There was a linear correlation (r(2)=0.91) between infarct size and Δt, indicating that the cardioprotective effect of delayed postconditioning was progressively attenuated when Δt time increased. The protective effect of PostC(Δ1) and PostC(Δ15) was still effective when the duration of reperfusion was prolonged to 24 hours (IR(24 hours); PostC(Δ1) and PostC(Δ15) versus IR(24 hours), P=0.001). Similar results were obtained for internucleosomal DNA fragmentation and lactate dehydrogenase release. CONCLUSIONS: This study in our in vivo mouse model of myocardial IR shows for the first time that delaying the intervention of postconditioning to 30 minutes does not abrogate the cardioprotective effect of postconditioning. This finding provides evidence that the time window of protection afforded by postconditioning may be larger than initially reported.

Three-year monitoring and comparison of results from two identical blood gas analyzers.

Objectives: Measurement comparability between blood gas analyzers within a laboratory is of utmost importance. This study analyzed the data obtained from a three-year period. Design and methods: For quality monitoring one blood sample was tested on two identical blood gas analyzers at each of three shifts/day for three years. Deming regression analysis was used to determine result correlation and statistical identity between the two analyzers for pH, pCO2, pO2, sodium, potassium, chloride, ionized calcium, glucose, and lactate. Failures in the two-analyzer comparison were determined by the performance limits from the Institute of Quality Management in Healthcare (IQMH) and from the manufacturer respectively. Results: Correlation coefficients were greater than 0.96 (0.9622-0.9975) for all tested analytes. The measurements of every analyte on both analyzers were statistically identical. In the two-analyzer comparison failure numbers/1000 tests for pO2 and glucose varied with the performance limits (IQMH: 0.6 and 49.2; the manufacturer: 19.3 and 4.4, respectively). In addition, persistent glucose failures (>5/week) between the two analyzers occurred occasionally. Conclusions: Results of all tested analytes between the two blood gas analyzers were interchangeable. Recurring glucose discrepancies might be a result of different lots of cartridges used on each analyzer, which were not identified during the initial installation.

Evaluation of Next-Generation Sequencing Applied to Cryptosporidium parvum and Cryptosporidium hominis Epidemiological Study.

Background. Nowadays, most of the C. parvum and C. hominis epidemiological studies are based on gp60 gene subtyping using the Sanger sequencing (SgS) method. Unfortunately, SgS presents the limitation of being unable to detect mixed infections. Next-Generation Sequencing (NGS) seems to be an interesting solution to overcome SgS limits. Thus, the aim of our study was to (i) evaluate the reliability of NGS as a molecular typing tool for cryptosporidiosis, (ii) investigate the genetic diversity of the parasite and the frequency of mixed infections, (iii) assess NGS usefulness in Cryptosporidium sp. outbreak investigations, and (iv) assess an interpretation threshold of sequencing data. Methods. 108 DNA extracts from positive samples were sequenced by NGS. Among them, two samples were used to validate the reliability of the subtyping obtained by NGS and its capacity to detect DNA mixtures. In parallel, 106 samples from French outbreaks were used to expose NGS to epidemic samples. Results. NGS proved suitable for Cryptosporidium sp. subtyping at the gp60 gene locus, bringing more genetic information compared to SgS, especially by working on many samples simultaneously and detecting more diversity. Conclusions. This study confirms the usefulness of NGS applied to C. hominis and C. parvum epidemiological studies, especially aimed at detecting minority variants.