Inflammasome-mediated pyroptosis in defense against pathogenic bacteria.

Macrophages, neutrophils, and epithelial cells are pivotal components of the host's immune response against bacterial infections. These cells employ inflammasomes to detect various microbial stimuli during infection, triggering an inflammatory response aimed at eradicating the pathogens. Among these inflammatory responses, pyroptosis, a lytic form of cell death, plays a crucial role in eliminating replicating bacteria and recruiting immune cells to combat the invading pathogen.

Neutrophil inflammasomes sense the subcellular delivery route of translocated bacterial effectors and toxins.

In neutrophils, caspase-11 cleaves gasdermin D (GSDMD), causing pyroptosis to clear cytosol-invasive bacteria. In contrast, caspase-1 also cleaves GSDMD but seems to not cause pyroptosis. Here, we show that this pyroptosis-resistant caspase-1 activation is specifically programmed by the site of translocation of the detected microbial virulence factors.

USP21 Deubiquitinase Regulates AIM2 Inflammasome Activation.

Innate immune sensing of cytosolic DNA via absent in melanoma 2 (AIM2) is a key mechanism leading to inflammatory responses. As aberrant immune responses by dysregulated AIM2 are associated with autoinflammatory diseases, activation of the AIM2 inflammasome should be tightly controlled. In this study, we discovered that ubiquitination and deubiquitination of AIM2 are critical events that regulate AIM2 inflammasome activation.

Evaluating cytokine production by flow cytometry using brefeldin A in mice.

Characterizing cytokine production is important for properly understanding immunologic responses. Cytokine reporter mice are limited by the need to cross markers into various knockout backgrounds and by availability of reporters of interest. To overcome this, we utilize injection of brefeldin A into mice to enable flow cytometric analysis of cytokine production during a bacterial infection.

Neutrophil Caspase-11 Is Essential to Defend against a Cytosol-Invasive Bacterium.

Either caspase-1 or caspase-11 can cleave gasdermin D to cause pyroptosis, eliminating intracellular replication niches. We previously showed that macrophages detect Burkholderia thailandensis via NLRC4, triggering the release of interleukin (IL)-18 and driving an essential interferon (IFN)-γ response that primes caspase-11. We now identify the IFN-γ-producing cells as a mixture of natural killer (NK) and T cells.

The ABCs of Voiding Cystourethrography.

Voiding cystourethrography (VCUG) demonstrates the anatomy of the urinary system and is used to detect the presence/absence of vesicoureteral reflux. It is the most important modality for urological fluoroscopic examination in children. For improved patient care, it is important to understand and perform VCUG appropriately.

Designing a Chatbot for a Brief Motivational Interview on Stress Management: Qualitative Case Study.

Background: In addition to addiction and substance abuse, motivational interviewing (MI) is increasingly being integrated in treating other clinical issues such as mental health problems. Most of the many technological adaptations of MI, however, have focused on delivering the action-oriented treatment, leaving its relational component unexplored or vaguely described. This study intended to design a conversational sequence that considers both technical and relational components of MI for a mental health concern.

A central role for PI3K-AKT signaling pathway in linking SAMHD1-deficiency to the type I interferon signature.

The autoimmune disorder Aicardi-Goutières syndrome (AGS) is characterized by a constitutive type I interferon response. SAMHD1 possesses both dNTPase and RNase activities and mutations in SAMHD1 cause AGS; however, how SAMHD1-deficiency causes the type I interferon response in patients with AGS remains unknown. Here, we show that endogenous RNA substrates accumulated in the absence of SAMHD1 act as a major immunogenic source for the type I interferon response.

SAMHD1, the Aicardi-Goutières syndrome gene and retroviral restriction factor, is a phosphorolytic ribonuclease rather than a hydrolytic ribonuclease.

SAMHD1 plays diverse roles in innate immunity, autoimmune diseases and HIV restriction, but the mechanisms involved are still unclear. SAMHD1 has been reported to have both dNTPase and RNase activities. However, whether SAMHD1 possesses RNase activity remains highly controversial.

SAMHD1 specifically restricts retroviruses through its RNase activity.

Background: Human SAMHD1 possesses dual enzymatic functions. It acts as both a dGTP-dependent triphosphohydrolase and as an exoribonuclease. The dNTPase function depletes the cellular dNTP pool, which is required for retroviral reverse transcription in differentiated myeloid cells and resting CD4(+) T cells; thus this activity mainly plays a role in SAMHD1-mediated retroviral restriction.

The ribonuclease activity of SAMHD1 is required for HIV-1 restriction.

The HIV-1 restriction factor SAM domain- and HD domain-containing protein 1 (SAMHD1) is proposed to inhibit HIV-1 replication by depleting the intracellular dNTP pool. However, phosphorylation of SAMHD1 regulates its ability to restrict HIV-1 without decreasing cellular dNTP levels, which is not consistent with a role for SAMHD1 dNTPase activity in HIV-1 restriction. Here, we show that SAMHD1 possesses RNase activity and that the RNase but not the dNTPase function is essential for HIV-1 restriction.

Redox-regulated peptide transfer from the transporter associated with antigen processing to major histocompatibility complex class I molecules by protein disulfide isomerase.

Most antigenic peptides are generated by proteasomes in the cytosol and are transported by the transporter associated with antigen processing (TAP) into the endoplasmic reticulum, where they bind with nascent major histocompatibilitiy complex class I molecule (MHC-I). Although the overall process of peptide-MHC-I complex assembly is well studied, the mechanism by which free peptides are delivered from TAP to MHC-I is unknown. In this study, we investigated the possible role of protein disulfide isomerase (PDI) as a peptide carrier between TAP and MHC-I.

Spatially resolvable optical emission spectrometer for analyzing density uniformity of semiconductor process plasma.

We proposed a spatially resolved optical emission spectrometer (SROES) for analyzing the uniformity of plasma density for semiconductor processes. To enhance the spatial resolution of the SROES, we constructed a SROES system using a series of lenses, apertures, and pinholes. We calculated the spatial resolution of the SROES for the variation of pinhole size, and our calculated results were in good agreement with the measured spatial variation of the constructed SROES.

Protein disulphide isomerase is required for signal peptide peptidase-mediated protein degradation.

The human cytomegalovirus glycoprotein US2 induces dislocation of MHC class I heavy chains from the endoplasmic reticulum (ER) into the cytosol and targets them for proteasomal degradation. Signal peptide peptidase (SPP) has been shown to be integral for US2-induced dislocation of MHC class I heavy chains although its mechanism of action remains poorly understood. Here, we show that knockdown of protein disulphide isomerase (PDI) by RNA-mediated interference inhibited the degradation of MHC class I molecules catalysed by US2 but not by its functional homolog US11.

A role for protein disulfide isomerase in the early folding and assembly of MHC class I molecules.

Proper folding and assembly of major histocompatibility complex (MHC) class I complexes are essential for optimal peptide loading and subsequent antigen presentation. MHC class I folding involves the coordinated formation of multiple disulfide bonds within MHC class I molecules. However, the regulation of disulfide bond formation during the early process of MHC class I folding is uncharacterized.

Molecular mechanisms of MHC class I-antigen processing: redox considerations.

Major histocompatibility complex (MHC) class I molecules present antigenic peptides to the cell surface for screening by CD8(+) T cells. A number of ER-resident chaperones assist the assembly of peptides onto MHC class I molecules, a process that can be divided into several steps. Early folding of the MHC class I heavy chain is followed by its association with beta(2)-microglobulin (beta(2)m).