BA.1 breakthrough infection elicits distinct antibody and memory B cell responses in vaccinated-only versus hybrid immunity individuals.

Immune memory is influenced by the frequency and type of antigenic challenges. Here, we performed a cross-sectional comparison of immune parameters following a BA.1 breakthrough infection in individuals with prior hybrid immunity (conferred by infection and vaccination) versus those solely vaccinated in a cohort of health care workers in Lyon, France.

Memory B Cells Provide Long-Term Protection to Vaccinated Kidney Transplant Recipients Against SARS-CoV-2 Variants.

Kidney transplant recipients (KTRs) are highly vulnerable to COVID-19. An intensified scheme of vaccination offers short-term protection to the 50%-75% of KTRs able to develop a germinal center reaction, required for the generation of neutralizing titers of antibodies (NAbs). However, the duration of this vaccinal protection is unknown.

Hamster organotypic kidney culture model of early-stage SARS-CoV-2 infection highlights a two-step renal susceptibility.

Kidney pathology is frequently reported in patients hospitalized with COVID-19, the pandemic disease caused by the Severe acute respiratory coronavirus 2 (SARS-CoV-2). However, due to a lack of suitable study models, the events occurring in the kidney during the earliest stages of infection remain unknown. We have developed hamster organotypic kidney cultures (OKCs) to study the early stages of direct renal infection.

Predictive factors of a viral neutralizing humoral response after a third dose of COVID-19 mRNA vaccine.

Kidney transplant recipients (KTRs) have reduced ability to mount adequate antibody response after two doses of the COVID-19 mRNA vaccine. French health authorities have allowed a third booster dose (D3) for KTRs, but their response is heterogeneous and tools able to discriminate the responders are lacking. Anti-RBD IgG titers (chemiluminescence immunoassay), spike-specific cellular responses (IFN-γ-releasing assay, IGRA), and in vitro serum neutralization of the virus (the best available correlate of protection), were evaluated 7-14 days after the second dose (D2) of BNT162b2 vaccine in 93 KTRs.

Infection or a third dose of mRNA vaccine elicits neutralizing antibody responses against SARS-CoV-2 in kidney transplant recipients.

Transplant recipients, who receive therapeutic immunosuppression to prevent graft rejection, are characterized by high coronavirus disease 2019 (COVID-19)-related mortality and defective response to vaccines. We observed that previous infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but not the standard two-dose regimen of vaccination, provided protection against symptomatic COVID-19 in kidney transplant recipients. We therefore compared the cellular and humoral immune responses of these two groups of patients.

A prospective observational study for justification, safety, and efficacy of a third dose of mRNA vaccine in patients receiving maintenance hemodialysis.

The level of protection achieved by the standard two doses of COVID-19 mRNA vaccines in patients receiving maintenance hemodialysis (MHD) remains unclear. To study this we used the French Renal Epidemiology and Information Network (REIN) Registry to compare the incidence and severity of 1474 cases of COVID-19 diagnosed in patients receiving MHD after none, one or two doses of vaccine. Vaccination significantly reduce COVID-19 incidence and severity, but 11% of patients infected after two doses still died.

The ROMANOV study found impaired humoral and cellular immune responses to SARS-CoV-2 mRNA vaccine in virus-unexposed patients receiving maintenance hemodialysis.

Patients on maintenance hemodialysis (MHD), which are at high risk of infection by SARS-CoV-2 virus and death due to COVID-19, have been prioritized for vaccination. However, because they were excluded from pivotal studies and have weakened immune responses, it is not known whether these patients are protected after the "standard" two doses of mRNA vaccines. To answer this, anti-spike receptor binding domain (RBD) IgG and interferon gamma-producing CD4 and CD8 specific-T cells were measured in the circulation 10-14 days after the second injection of BNT162b2 vaccine in 106 patients receiving MHD (14 with history of COVID-19) and compared to 30 healthy volunteers (four with history of COVID-19).

Improved cell signaling analysis by biofunctionalized nanospheres and imaging flow cytometry.

The analysis of immune cell signaling is critical for the understanding of the biology and pathology of the immune system, and thus a mandatory step for the development of efficient biomarkers and targeted therapies. Phosflow, which has progressively replaced the traditional western blot approach, relies on flow cytometry to analyze various signaling pathways at a single-cell level. This technique however suffers a lack of sensitivity largely due to the low signal/noise ratio that characterizes cell signaling analysis.

Chronic Kidney Disease-Associated Immune Dysfunctions: Impact of Protein-Bound Uremic Retention Solutes on Immune Cells.

Regardless of the primary disease responsible for kidney failure, patients suffering from chronic kidney disease (CKD) have in common multiple impairments of both the innate and adaptive immune systems, the pathophysiology of which has long remained enigmatic. CKD-associated immune dysfunction includes chronic low-grade activation of monocytes and neutrophils, which induces endothelial damage and increases cardiovascular risk. Although innate immune effectors are activated during CKD, their anti-bacterial capacity is impaired, leading to increased susceptibility to extracellular bacterial infections.