Immunology

Active Surveillance and Decolonization Without Isolation Is Effective in Preventing Methicillin-Resistant Staphylococcus aureus Transmission in the Psychiatry Units
Control of methicillin-resistant Staphylococcus aureus (MRSA) is difficult in select populations. We used molecular typing to study the effect of universal surveillance and decolonization of carriers, without isolation, on MRSA transmission in a specialized unit. Patients admitted to the unit were screened for nasal MRSA at admission and discharge. Those who acquired MRSA during their stay were...


Fatal Acanthamoeba Encephalitis in a Patient With a Total Artificial Heart (Syncardia) Device
Acanthamoeba encephalitis is an uncommon but often fatal infection complication. Here we report the first case of Acanthamoeba encephalitis in a patient with a Total Artificial Heart device.
Serial Transfer of Single-Cell-Derived Immunocompetence Reveals Stemness of CD8+ Central Memory T Cells
Long-term persistence of adaptive immunity is suggested to rely on stem-cell-based mechanisms. Graef et al. show that upon serial single-cell transfers, propagation of protective T cell memory can be established by individual central memory T cells acting as self-renewing, multipotent tissue stem cells.


MicroRNA-Containing T-Regulatory-Cell-Derived Exosomes Suppress Pathogenic T Helper 1 Cells
The mechanisms through which T regulatory (Treg) cells prevent inflammation are not fully understood. Okoye et al. show that Treg cells release exosomes that transfer miRNAs to target T helper cells and suppress T-cell-mediated disease.
Tumor-Associated Macrophages: From Mechanisms to Therapy
Macrophages promote tumor progression to malignancy. Noy and Pollard discuss how macrophages both stimulate tumor cell growth and suppress antitumor immune responses and propose ablation or redifferentiation of macrophages in tumors as a promising therapeutic approach to treat cancer.


Macrophages, Immunity, and Metabolic Disease
Chronic, low-grade adipose tissue inflammation is a key etiological mechanism linking type 2 diabetes and obesity. McNelis and Olefsky outline how the immune system integrates with metabolism and discuss how macrophages are critical effector cells in the initiation of inflammation and insulin resistance.
Macrophages Have a Grip on the Gut
We host a world inside, and every day, new evidence reveals how relevant our microbiota is for daily living. Muller and colleagues demonstrate that microbiota commensals also influence colon peristalsis via a direct effect of muscolaris externae macrophages (Muller et al., 2014).

Tfr Cells and IgA Join Forces to Diversify the Microbiota
How diversity of the microbiota is generated and maintained is an open question. Kawamoto et al. show that T follicular regulatory cells foster microbiota diversity via the regulation of IgA selection.
Memory T Cells Officially Join the Stem Cell Club
Graef et al. demonstrate self-renewal and multipotency of a single CD62L+ memory T cell across serial adoptive transfers and infection-driven re-expansions, providing evidence of true stemness within the T cell memory compartment.

Regulatory T Cells: Exosomes Deliver Tolerance
T regulatory (Treg) cells enforce peripheral tolerance through regulation of diverse immune responses in a context-dependent manner. Okoye et al. show one way in which Treg cells suppress Th1 cell responses is through nonautonomous gene silencing mediated by microRNA-containing exosomes.
Futility Sustains Memory T Cells
Memory T cells display a distinct metabolic profile compared to effector T cells. In this issue, O’Sullivan et al. report that memory T cells activate a “futile cycle” of de novo fatty-acid synthesis and concurrent fatty-acid oxidation to generate ATP for cell survival.

Symbiotic Bacterial Metabolites Regulate Gastrointestinal Barrier Function via the Xenobiotic Sensor PXR and Toll-like Receptor 4
How commensal microbial metabolites affect mucosal integrity and barrier function is unclear. Mani and colleagues show that indole 3 propionic acid regulates intestinal barrier permeability through the PXR-TLR4 pathway.
Galectin-9-CD44 Interaction Enhances Stability and Function of Adaptive Regulatory T Cells
Galectin-9 is crucial for the generation and function of induced regulatory T (iTreg) cells, but not natural Treg cells. Kuchroo and colleagues demonstrate that exogenous galectin-9 acts synergistically with TGF-β to enforce iTreg cell differentiation and maintenance.
Bacterial Sensor Nod2 Prevents Inflammation of the Small Intestine by Restricting the Expansion of the Commensal Bacteroides vulgatus
Deficient bacterial recognition by NOD2 is associated with inflammatory bowel disease. Cadwell and colleagues demonstrate that mice deficient in Nod2 display a pathological expansion of the commensal bacterium Bacteroides vulgatus and subsequent inflammatory abnormalities in the small intestine.
MHCII-Mediated Dialog between Group 2 Innate Lymphoid Cells and CD4+ T Cells Potentiates Type 2 Immunity and Promotes Parasitic Helminth Expulsion
Type-2 innate lymphoid cells proliferate and release interleukin-13 during protective immunity to helminth infection and detrimentally during allergy and asthma. McKenzie and colleagues establish that these activities are potentiated through an MHC class II-mediated dialogue with T cells.