Clinical Phenotypes and Molecular Characteristics of Respiratory Syncytial Virus in Adults: A Monocentric Prospective Study Between 2019 and 2022

Respiratory syncytial virus (RSV) infection is a major cause of pneumonia in adults. Little is known on the viral genetic diversity and the associated clinical phenotypes in this population. This single-center prospective cohort study included RSV-infected patients hospitalized between January 2019 and December 2022. Of 100 patients, including 41 with severe infection, 72 were infected with RSV-B. RSV genome sequencing showed no clustering according to severity. Patients infected with RSV-B with risk factors for severe pneumonia had significantly higher fusion protein diversity scores. No amino acid substitutions conferring resistance to nirsevimab were detected.

Evaluation of the contribution of shotgun metagenomics in the microbiological diagnosis of liver abscesses

BACKGROUND

Shotgun metagenomics (SMg) sequencing has gained a considerable interest, as it enables the detection of any microorganisms through a single analysis. Due to the limitations of standard microbiological approaches, the microbial documentation of liver abscesses (LA), which is crucial for their medical management, can be difficult. Here we aimed to compare the performance of SMg with standard approaches for the microbiological documentation of LA.

METHODS

In this retrospective study conducted at two centers, we compared the results of standard microbiology with metagenomics analysis of consecutive LA samples. For samples tested positive for Klebsiella pneumoniae, we compared the analysis of virulence and resistance genes using metagenomics data to whole-genome sequencing of corresponding isolates obtained in culture.

RESULTS

Out of the 62 samples included, standard approaches and SMg yielded documentation in 80.6% and 96.8%, respectively. In 37.1% (23/62) of cases, both methods showed identical results, whereas in 43.5% (27/62) of cases, the samples were positive by both methods, but SMg found additional species in 88.9% (24/27), mostly anaerobes. When the standard approaches were negative, the SMg was able to detect microorganisms in 80.0% of cases (8/10). Overall, SMg identified significantly more microorganisms than culture (414 vs.105; p<0.05). K. pneumoniae genome analysis was able to detect resistance and virulence genes with a level of sensitivity depending on the depth of sequencing.

DISCUSSION

Overall, we showed that SMg had better performance in detecting and identifying microorganisms from LA samples and could help characterizing strain's resistome and virulome. Although still costly and requiring specific skills and expensive equipment, MGs methods are set to expand in the future.

Shotgun metagenomic screening to improve the retrospective diagnosis of undocumented intrauterine infections on embedded placenta samples: Lessons from a brucellosis case

BACKGROUND

Microbiological diagnosis of intrauterine infections (IIU) still relies on bacteriological cultures or targeted DNA amplification lacking in sensitivity. Shotgun metagenomics (SMg) is an emerging unbiased molecular approach that makes it possible to sequence all the nucleic acids from any sample. It had never previously been used for IIU.

METHODS

We here report the case of a patient with an unexplained IIU and fetal loss that could be documented by a combined SMg/microbiological approach, leading to the diagnosis of maternal brucellosis.

RESULTS

A 31-year-old woman presented with an undocumented IIU with fetal loss at 24 weeks of gestation. Culture-based work-up failed to identify the pathogen involved. Paraffin-embedded placenta sample was retrospectively analyzed by SMg. Brucella spp nucleic acids were detected, and subacute maternal brucellosis was confirmed by targeted PCR and serological testing.

CONCLUSION

This case provides grounds for further utilization of SMg for the microbiological diagnosis of unexplained obstetrical infections.

Unknown Circovirus in Immunosuppressed Patient with Hepatitis, France, 2022

Hepatitis of undetermined origin can be caused by a wide variety of pathogens, sometimes emerging pathogens. We report the discovery, by means of routine shotgun metagenomics, of a new virus belonging to the family Circoviridae, genus Circovirus, in a patient in France who had acute hepatitis of unknown origin.

Inhibition of fatty acid amide hydrolase activates Nrf2 signalling and induces heme oxygenase 1 transcription in breast cancer cells

BACKGROUND AND PURPOSE

Endocannabinoids such as anandamide (AEA) are important lipid ligands regulating cell proliferation, differentiation and apoptosis. Their levels are regulated by hydrolase enzymes, the fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MGL). Here, we investigated whether FAAH or AEA are involved in NF (erythroid-derived 2)-like 2 (Nrf2)/antioxidant responsive element (ARE) pathway.

EXPERIMENTAL APPROACH

The aim of this study was to analyse the effects of AEA or FAAH inhibition by the URB597 inhibitor or FAAH/siRNA on the activation of Nrf2-ARE signalling pathway and heme oxygenase-1 (HO-1) induction and transcription.

KEY RESULTS

Endogenous AEA was detected in the immortalized human mammary epithelial MCF-10A cells (0.034 ng per 10(6) cells) but not in MCF-7 or MDA-MB-231 breast cancer cells. Because breast tumour cells express FAAH abundantly, we examined the effects of FAAH on Nrf2/antioxidant pathway. We found that inhibition of FAAH by the URB597 inhibitor induced antioxidant HO-1 in breast cancer cells and MCF-10A cells. RNAi-mediated knockdown of FAAH or treatment with AEA-activated ARE-containing reporter induced HO-1 mRNA and protein expression, independent of the cannabinoid receptors, CB1, CB2 or TRPV1. Furthermore, URB597, AEA and siRNA-FAAH treatments induced the nuclear translocation of Nrf2, while siRNA-Nrf2 treatment and Keap1 expression blocked AEA, URB597 and si-FAAH from activation of ARE reporter and HO-1 induction. siRNA-HO-1 treatment decreased the viability of breast cancer cells and MCF-10A cells.

CONCLUSIONS AND IMPLICATIONS

These data uncovered a novel mechanism by which inhibition of FAAH or exposure to AEA induced HO-1 transcripts and implicating AEA and FAAH as direct modifiers in signalling mediated activation of Nrf2-HO-1 pathway, independent of cannabinoid receptors.

NRP/B mutations impair Nrf2-dependent NQO1 induction in human primary brain tumors

Brain tumors are associated with genetic alterations of oncogenes and tumor suppressor genes. Accumulation of reactive oxygen species (ROS) in cells leads to oxidative stress-induced damage, resulting in tumorigenesis. Here, we showed that the nuclear matrix protein nuclear restricted protein in brain (NRP/B) was colocalized and interacted with NF-E2-related factor 2 (Nrf2). During oxidative stress response, NRP/B expression and its interaction with Nrf2 were upregulated in SH-SY5Y cells. Association of NRP/B with Nrf2 was crucial for NAD(P)H:quinone oxidoreductase 1 (NQO1) expression. NRP/B was localized predominantly in the nucleus of normal brain cells, whereas in primary brain tumors NRP/B was almost exclusively contained in the cytoplasm. In addition, unlike wild-type NRP/B, the expression of NRP/B mutants isolated from primary brain tumors was found in the cytoplasm, and these mutants failed to induce Nrf2-dependent NQO1 transcription. Thus, NRP/B mutations and their altered localization resulted in changes in NRP/B function and deregulation of Nrf2-dependent NQO1 activation in brain tumors. This study provides insights into the mechanism by which the NRP/B modulates Nrf2-dependent NQO1 induction in cellular protection against ROS in brain tumors.

Impact of radiation (RT) regimen on palliative procedures (PP) for patients with resectable locally advanced esophageal cancer treated with exclusive chemoradiation (CRT) or preoperative chemoradiation (CRT+S): results from a phase III trial of the Federation Francophone de Cancerologie Digestive (FFCD 9102)

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Background: The FFCD 9102 trial demonstrated that CRT is an alternative to CRT+S for responding patients. We investigated the type of PP in the follow-up (FU) period, according to the RT scheme: protracted (P-RT) vs. split course (SC-RT). Methods: Resectable T3 N0–1 M0 thoracic esophageal carcinoma were included. First sequence : 2 cycles of cisplatin and 5-FU (day (d)1 - d22) combined with RT. Two schemes of RT were allowed: P-RT (46 Gy / 4.5 weeks (w), 2 Gy / f) or SC-RT (2 one-week courses of 15 Gy, 3 Gy / f). For CRT, the same chemotherapy was given on d43, d64 and d92 combined with 20 Gy / 2w (P-RT) or 15 Gy / 1w (SC-RT). Responding patients after the first sequence were randomized between CRT and CRT+S. The impact of SC-RT vs. P-RT on PP in the FU period was explored using a Mann-Whitney test. Results: From February 1993 to December 2000, 451 pts were registered and 446 were eligible. P-RT: 161 pts, SC-RT: 285 pts. After a median FU of 47.4 months, 2-year overall survival and local relapse-free survival were for P-RT vs. SC-RT: 37.1% vs. 30.5% (p = 0.25) and 76.7% vs. 56.8% (p = 0.002), respectively. P-RT vs. SC-RT: mean length of hospital stay: 48 d vs. 60.5 d (p= 0.0003). Mean number of dilatation sessions: 0.56 vs. 0.66 (p= 0.43). Mean number of stents: 0.21 vs. 0.34 (p= 0.03). Mean number of any PP: 1.01 vs. 1.50 (p= 0.001). Mean dysphagia grade: 2.99 vs. 3.12 (p= 0.21). In the CRT+S-group, P-RT vs. SC-RT: mean length of hospital stay 55.0d vs. 68.7d (p =0.051). Mean number of dilatation sessions: 0.74 vs. 0.74 (p= 0.77). Mean number of stents: 0.09 vs. 0.18 (p= 0.44). Mean number of PP: 1.00 vs. 1.37 (p= 0.054). In the CRT-group, P-RT vs. SC-RT, mean length of hospital stay: 42.6d vs 54.0d (p= 0.053). Mean number of dilatation sessions : 0.38 vs. 0.67 (p= 0.12). Mean number of stents: 0.31 vs. 0.50 (p= 0.03). Mean number of PP: 0.83 vs. 1.86 (p= 0.0005). Conclusions: Stents, rate of PP and length of hospital stay were significantly increased with SC-RT. Dysphagia score was similar between SC-RT and P-RT at last FU.

No significant financial relationships to disclose.

SAG1 Is a Host-Targeted Antigen for Protection against Toxoplasma gondii Infection

We previously reported that SAG1 transgenic (tg) mice have an elevated susceptibility resulting from their inability to elicit strong Th1-based protection against Toxoplasma gondii infection. Here, we demonstrate that SAG1 tg mice were protected against T. gondii infection, characterized by a decline in IFN-gamma levels, following administration of a lethal dose of T. gondii. Moreover, immunization with T. gondii homogenate conferred protection and induced production of IgG, with IgG1 and IgG2a subclasses driven by Th2 and Th1 responses, respectively, in both SAG1 tg and wild-type (wt) mice. IgG titers were significantly higher from day 10 after immunization in wt mice compared to those in SAG1 tg mice. There were no significant differences observed in levels of IgG1 in both groups. However, significantly lower IgG2a titers were measured in the sera from SAG1 tg mice on days 10, 15 and 20. IFN-gamma levels in sera were significantly lower in SAG1 tg mice compared to those in wt mice on day 20 after immunization. When challenged with a lethal dose of the Beverley strain of T. gondii, 80 and 100% survival rates were observed in SAG1 tg and wt mice, respectively, indicating that SAG1 tg mice were protected to a lesser extent from challenge due to the decrease in protective immunity. These results suggest that SAG1 plays a critical role in eliciting protection, hence a target antigen for the development of protective Th1-based responses against T. gondii infection in mice.

Unresponsiveness to surface antigen 1 modifies cytokine profiles in acute Toxoplasma gondii infection

Resistance to Toxoplasma gondii involves the development of a highly polarized Th1-type cytokine expression. SAG1 transgenic mice are highly susceptible to T. gondii infection due to their non-reactivity to SAG1 of the protozoan parasite. Here we describe cytokine profiles during the acute phase of T. gondii infection, which are associated with the susceptibility of SAG1 transgenic mice. SAG1 transgenic mice showed a 4.5-fold increase in susceptibility upon inoculation with a sublethal dose of the Beverley strain of T. gondii compared to their wild-type counterparts (mortality: 81 vs. 18%, respectively). When analysis of the most important cytokines involved in the mediation of resistance to infection was carried out, SAG1 transgenic mice exhibited low production levels of IL-12, IFN-gamma and TNF-alpha in sera during the acute phase of T. gondii infection. Antibody and T cells specific for SAG1 were not mounted upon SAG1 stimulation in SAG1 transgenic mice. Moreover, in vitro studies indicated that in SAG1 transgenic mice IFN-gamma and IL-12 production was lower than in their wild-type counterparts, although levels of TNF-alpha increased in SAG1 transgenic mice on day 9 after infection. Low IgG2a levels were detected in SAG1 transgenic mouse sera. Unresponsiveness to SAG1 of T. gondii renders SAG1 transgenic mice unable to develop a strong Th1-based protection against T. gondii infection. These results provide evidence that SAG1 is a pivotal antigen involved in the induction of immune responses towards the development of Th1-protective immunity during T. gondii infection.

The WD motif-containing protein receptor for activated protein kinase C (RACK1) is required for recruitment and activation of signal transducer and activator of transcription 1 through the type I interferon receptor

An obligatory step in the activation of Signal Transducers and Activators of Transcription (STATs) by cytokines is their docking to specific receptors via phosphotyrosines. However, this model does not address whether STATs pre-associate with their corresponding receptor or exist free in the cytoplasm before receptor activation. In this report, we demonstrate that pre-association of STAT1 with the receptor is required for type I interferon (IFN) signaling. Interestingly, the interaction between the human type I IFN receptor and STAT1 is not direct but mediated by the adapter protein receptor for activated protein kinase C (RACK1). Disruption of the IFNalpha receptor-RACK1 interaction abolishes not only IFNalpha-induced tyrosine phosphorylation of STAT1 but also activation of STAT2, indicating that RACK1 plays a central role in early signaling through the Jak-STAT pathway. These findings demonstrate the involvement of RACK1 in STAT1 activation and raise the possibility that other STATs may pre-associate with cytokine receptors through similar adapter-STAT-mediated interactions.

Expression of SAG-1 of Toxoplasma gondii in transgenic mice

We describe the expression of SAG-1 cDNA in B6C3F1 mice by microinjecting a 3.3 kbp DNA fragment, consisting of the cytomegalovirus enhancer-chicken beta-actin hybrid promoter and SAG-1 into the pronucleus of a fertilized egg at the one-cell stage. Offspring derived from this microinjection were analyzed for the integration and functional expression of the SAG-1 transgene. Steady-state expressions of both the mRNA for SAG-1 and SAG-1 protein product were detected in the brain, thymus, spleen and liver. Approximately 50% of F1 and F2 progeny inherited the SAG-1 transgene from SAG-1 transgenic mice in Mendelian fashion. These results indicated that SAG-1 transgenic lines were established. Transgenic mice harboring the SAG-1 gene will contribute a critical tool of defining the molecular mechanisms of SAG-1 in pathogenesis and host immune response.

Increased susceptibility to Toxoplasma gondii infection in SAG-1 transgenic mice

SAG-1, one of the major surface proteins of Toxoplasma gondii, has been reported to play an important role in immune and pathogenic mechanisms of the parasites but its exact function is still unclear. We investigated the time courses of T. gondii infection in B6C3F1 transgenic mice carrying the SAG-1 gene. SAG-1 transgenic mice were infected intraperitoneally with a high virulent RH strain or a low virulent Beverley strain of T. gondii. When infected with RH strain tachyzoites, no significant differences in time courses of survivals between SAG-1 transgenic and wild-type mice were observed. Both groups succumbed to an acute infection within 8 days after infection. However, a lower survival rate (20%) was observed in SAG-1 transgenic mice than in wild-type (80%), when infected with Beverley strain cysts. This result indicates that SAG-1 transgenic mice are more susceptible to T. gondii infection as compared with their wild-type counterpart. ELISA using recombinant SAG-1 protein indicates that SAG-1 transgenic mice do not produce antibodies to the SAG-1 molecule. These findings may provide a critical tool for analysing the molecular mechanisms of pathogenesis and host immune responses during toxoplasmosis.

Roles of CD4(+) T cells and gamma interferon in protective immunity against Babesia microti infection in mice

Babesia microti produces a self-limiting infection in mice, and recovered mice are resistant to reinfection. In the present study, the role of T cells in protective immunity against challenge infection was examined. BALB/c mice which recovered from primary infection showed strong protective immunity against challenge infection. In contrast, nude mice which failed to control the primary infection and were cured with an antibabesial drug did not show protection against challenge infection. Treatment of immune mice with anti-CD4 monoclonal antibody (MAb) diminished the protective immunity against challenge infection, but treatment with anti-CD8 MAb had no effect on the protection. Transfer of CD4(+) T-cell-depleted spleen cells resulted in higher parasitemia than transfer of CD8(+) T-cell-depleted spleen cells. A high level of gamma interferon (IFN-gamma), which was produced by CD4(+) T cells, was observed for the culture supernatant of spleen cells from immune mice, and treatment of immune mice with anti-IFN-gamma MAb partially reduced the protection. Moreover, no protection against challenge infection was found in IFN-gamma-deficient mice. On the other hand, treatment of immune mice with MAbs against interleukin-2 (IL-2), IL-4, or tumor necrosis factor alpha did not affect protective immunity. These results suggest essential requirements for CD4(+) T cells and IFN-gamma in protective immunity against challenge infection with B. microti.

Effect of radiation therapy on the potential doubling time of tumours in colorectal cancers

OBJECTIVE

The aim of the present study was to investigate the effects of standard fractionated radiation therapy on the kinetic parameters of colorectal adenocarcinomas.

METHODS

The study of tumour kinetics involved in vivo injection of bromodeoxyuridine. Endoscopic biopsies were obtained from the tumour and analysed with flow cytometry. This procedure provides a rapid calculation of qualitative parameters such as ploidy and quantitative parameters such as the in vivo S-phase fraction labelling index which indicates the percentage of cells that have entered into the cycle, the duration of S-phase (Ts) and the potential tumour doubling time (Tpot).

RESULTS

Thirty-eight colorectal carcinomas were studied without prior chemotherapy or radiation therapy (group 1) and ten rectal carcinomas were studied following radiation therapy (group 2). In diploid tumours, the labelling index was significantly lower in the post-radiotherapy group than in the pre-radiotherapy group (2.7 +/- 1.1% versus 6.4 +/- 4.2%, respectively; P= 0.01), and the Tpot was significantly longer after radiotherapy (group 2) (22.0 +/- 7.0 days versus 8.6 +/- 6.0 days, P = 0.002). Standard fractionated radiation therapy also appears to result in a longer Tpot in diploid adenocarcinomas of the colon and rectum. This effect was not observed in aneuploid tumours.

CONCLUSIONS

The effectiveness of hyperfractionated schedules of radiation therapy for aneuploid rectal tumours with short Tpot warrants further investigation in a larger patient population.

Quality control of radiotherapeutic treatment of medulloblastoma in a multicentric study: the contribution of radiotherapy technique to tumour relapse. The French Medulloblastoma Group

Between 06.86 and 11.89, 88 medulloblastoma or primitive neuroectodermic tumour (PNET) localised in the posterior fossa have been included in the M7 multicentric protocol, 82 received the totality of the radiotherapy treatment and were evaluable for this study. Twenty-two of these 82 patients relapsed: their radiotherapy treatment is analysed in the present study. In 10 cases out of the 22 relapses treatment failure was probably due to a radiotherapeutic imperfection. This study confirms the necessity of a strict radiotherapy control, particularly in multicentric study.