Type 1 interferons and Foxo1 down-regulation play a key role in age-related T-cell exhaustion in mice.

Foxo family transcription factors are critically involved in multiple processes, such as metabolism, quiescence, cell survival and cell differentiation. Although continuous, high activity of Foxo transcription factors extends the life span of some species, the involvement of Foxo proteins in mammalian aging remains to be determined. Here, we show that Foxo1 is down-regulated with age in mouse T cells. This down-regulation of Foxo1 in T cells may contribute to the disruption of naive T-cell homeostasis with age, leading to an increase in the number of memory T cells. Foxo1 down-regulation is also associated with the up-regulation of co-inhibitory receptors by memory T cells and exhaustion in aged mice. Using adoptive transfer experiments, we show that the age-dependent down-regulation of Foxo1 in T cells is mediated by T-cell-extrinsic cues, including type 1 interferons. Taken together, our data suggest that type 1 interferon-induced Foxo1 down-regulation is likely to contribute significantly to T-cell dysfunction in aged mice.

Efficacy of single antibiotic therapy versus antibiotic combination in implant-free staphylococcal post-surgical spinal infections: a retrospective observational study.

BACKGROUND: Post-surgical spinal infections (pSSIs) are a serious complication of spinal surgeries, with Staphylococcus spp. being one of the most prominent bacteria identified. Optimal antimicrobial therapy for staphylococcal spinal infections without spinal implants is not well documented. METHODS: This single center retrospective 7-year observational study described and compared the outcome (treatment failure or mortality rate one year after diagnosis) of 20 patients with staphylococcal-implant-free pSSI treated with single or combination antibiotics. RESULTS: Median duration of treatment was 40 days (IQR 38-42), with 6 days (IQR 5-7) on intravenous antibiotics and 34 days (IQR 30-36) on oral therapy. Four patients (20%) underwent new surgical debridement, all due to surgical failure, and 1 patient died within the first year without significant differences between both treatment group. CONCLUSION: This study raises the possibility of single antibiotic therapy for patients with implant-free post-surgical spinal infections due to Staphylococcus spp.

High Prevalence of OXA-23 Carbapenemase-Producing Proteus mirabilis among Amoxicillin-Clavulanate-Resistant Isolates in France.

In this multicentric study performed in 12 French hospitals, we reported that 26.9% (14/52) of the amoxicillin-clavulanate-resistant Proteus mirabilis isolates produced the OXA-23 carbapenemase. We found that an inhibition zone diameter of <11 mm around the amoxicillin-clavulanate disc was an accurate screening cutoff to detect these OXA-23 producers. We confirmed by whole-genome sequencing that these OXA-23-producers all belonged to the same lineage that has been demonstrated to disseminate OXA-23 or OXA-58 in P. mirabilis.

Ly6Chigh Monocytes Protect against Kidney Damage during Sepsis via a CX3CR1-Dependent Adhesion Mechanism.

Monocytes have a crucial role in both proinflammatory and anti-inflammatory phenomena occurring during sepsis. Monocyte recruitment and activation are orchestrated by the chemokine receptors CX3CR1 and CCR2 and their cognate ligands. However, little is known about the roles of these cells and chemokines during the acute phase of inflammation in sepsis. Using intravital microscopy in a murine model of polymicrobial sepsis, we showed that inflammatory Ly6C(high) monocytes infiltrated kidneys, exhibited altered motility, and adhered strongly to the renal vascular wall in a chemokine receptor CX3CR1-dependent manner. Adoptive transfer of Cx3cr1-proficient monocyte-enriched bone marrow cells into septic Cx3cr1-depleted mice prevented kidney damage and promoted mouse survival. Modulation of CX3CR1 activation in septic mice controlled monocyte adhesion, regulated proinflammatory and anti-inflammatory cytokine expression, and was associated with the extent of kidney lesions such that the number of lesions decreased when CX3CR1 activity increased. Consistent with these results, the pro-adhesive I249 CX3CR1 allele in humans was associated with a lower incidence of AKI in patients with sepsis. These data show that inflammatory monocytes have a protective effect during sepsis via a CX3CR1-dependent adhesion mechanism. This receptor might be a new therapeutic target for kidney injury during sepsis.

Adaptive Immune-like γ/δ T Lymphocytes Share Many Common Features with Their α/ß T Cell Counterparts.

To better apprehend γ/δ T cell biological functions in the periphery, it appears crucial to identify markers highlighting the existence of distinct phenotypic and functional γ/δ T cell subsets. Interestingly, the expression of CD44 and Ly-6C subdivides murine peripheral γ/δ T cells into several subsets, with Ly-6C(-) CD44(hi) γ/δ T cells corresponding to the IL-17-producing CD27(-) γ/δ T cell subset exhibiting innate-like features. By comparing the other subsets to naive and memory CD8(+) α/ß T cells, in this study, we show that Ly-6C(- or +) CD44(lo) and Ly-6C(+)CD44(hi) γ/δ T cells greatly resemble, and behave like, their CD8(+) α/ß T cell counterparts. First, like memory CD8(+) α/ß T cells, Ly-6C(+)CD44(hi) γ/δ T cells are sparse in the thymus but largely increased in proportion in tissues. Second, similarly to naive CD8 α/ß T cells, CD44(lo) γ/δ T cells are poorly cycling in vivo in the steady state, and their proportion declines with age in secondary lymphoid organs. Third, CD44(lo) γ/δ T cells undergo spontaneous proliferation and convert to a memory-like Ly-6C(+)CD44(hi) phenotype in response to lymphopenia. Finally, CD44(lo) γ/δ T cells have an intrinsic high plasticity as, upon appropriate stimulation, they are capable of differentiating nonetheless into Th17-like and Th1-like cells but also into fully functional Foxp3(+) induced regulatory T cell-like γ/δ T cells. Thus, peripheral CD27(+) γ/δ T cells, commonly considered as a functionally related T cell compartment, actually share many common features with adaptive α/ß T cells, as both lineages include naive-like and memory-like lymphocytes with distinct phenotypic, functional, and homeostatic characteristics.