Impact of viral vectors on vaccine design: IL-13Ra2 in DC regulation

Studies in our laboratory have established that the route of vaccination, viral vector and the cytokine milieu, specifically IL-13 can critically impact the vaccine-specific adaptive immune outcomes. Recent efforts in understanding which cells at the vaccination site produced IL-13 revealed that innate lymphoid cells (ILC)2 were the major source of this cytokine at the vaccination site 24h post delivery. Knowing that manipulating IL-13 levels at the vaccination site also significantly altered resident lung dendritic cell (DC) recruitment, this study focused on dissecting the underlying mechanisms by which ILCs and DCs regulated vaccine-specific immunity at the lung mucosae following intranasal vaccination. Poxviral and non-poxviral vaccine vectors induced uniquely different ILC-derived cytokine and DC profiles at the lung mucosae, 24 h post vaccination. For example, rFPV priming known to induce high avidity T cells, exhibited low ILC2-derived IL-13, high ILC1/ILC3-derived IFN-g and enhanced recruitment of CD11b+ CD103- conventional DCs (cDC). Whereas, rMVA, rVV and Influenza A vector priming, linked to low avidity T cells, induced opposing ILC-derived cytokine profiles, together with enhanced CD11b- CD103+ cross-presenting DCs and reduced cDCs. Interestingly, Rhinovirus (RV) and Adenovius type 5 (Ad5) vectors, also showed different ILC-derived cytokine profiles and predominant recruitment of CD11b- B220+ plasmacytoid DCs (pDC). Knowing that cDCs are associated with high avidity CD8 T cell priming and pDCs are involved in antibody differentiation, these findings showed that vaccine derived early ILC/DC profiles directly impact the downstream adaptive immune outcomes. When trying to unravel how IL-13 signalling modulated these vaccine-specific adaptive immune outcomes, unlike IL-13Ra1, IL-13Ra2 was found to be the major sensor and regulator of early IL-13 mediated DC activity. For the first time a dual role of IL-13Ra2 was unraveled on lung cDC, where low IL-13 was associated with IL-13Ra2 signalling via STAT3 activating TGF-b1, whilst, high IL-13 triggered sequestration by the same receptor. Interestingly, in this study differential IL-13 receptor mediated STAT3/STAT6 paradigms were observed, regulated collaboratively or independently by TGF-b1 and IFN-g. Low IL-13 driven early IL-13Ra2/STAT3 responses were regulated primarily by TGF-b1, whereas, high IL-13 driven IL-13Ra1/STAT6 responses were associated with IFN-gR expression bias. Moreover, inherent properties of viral vaccine vectors (host tropism, replication status and presence or absence of immunomodulatory genes), were also found to significantly alter the IL-4/IL-13 receptor regulation on lung DCs, in a time dependent manner. Specifically, the generation of a balanced adaptive immune outcome was associated with early regulation of IL-13Ra2, succeeded by IL-13Ra1/ IL-4Ra on lung DCs, as observed with rFPV vaccination unlike the other poxviral vectors tested. Collectively, findings of this thesis for the first time demonstrated the importance of understanding the mechanisms of IL-13 mediated DC regulation, at the vaccination site. Therefore, knowing these innate mechanisms associated with ILC/DC regulation may help design more efficacious vaccines and therapeutics against IL-13 related disease conditions

STAT3 determines IL-4 signalling outcomes in naïve T cells

IL-4 production is associated with low-avidity, poorly cytotoxic T cell induction that contributes to viral immune evasion and the failure of T cell-based vaccines. Yet, the precise mechanisms that regulate IL-4 signalling in T cells remain elusive. Mounting evidence indicates that cells can dynamically alter their IL-4/IL-13 receptor signature to modulate downstream immune outcomes upon pathogen encounter. Here, we describe how naïve (CD62L+CD44lo–mid) CD4 and CD8 T cells distinctly engage both STAT6 and STAT3 in response to IL-4. We further show that IL-4R⍺ expression is both time- and IL-4 concentration-dependent. Remarkably, our findings reveal that STAT3 inhibition can ablate IL-4R⍺ and affect transcriptional expression of other Stat and Jak family members. By extension, the loss of STAT3 lead to aberrant STAT6 phosphorylation, revealing an inter-regulatory relationship between the two transcription factors. Moreover, IL-4 stimulation down-regulated TGF-β1 and IFN-γR1 expression on naïve T cells, possibly signifying the broad regulatory implications of IL-4 in conditioning lineage commitment decisions during early infection. Surprisingly, naïve T cells were unresponsive to IL-13 stimulation, unlike dendritic cells. Collectively, these findings could be exploited to inform more efficacious vaccines, as well as design treatments against IL-4/IL-13-associated disease conditions

Gaia: Surveying Heavens

In this paper we attempt to study an ongoing astrometry mission of the European Space Agency (ESA), named Gaia, whose aim is to make the largest and most precise three-dimensional map of our Galaxy. We present the scientific goals of Gaia and give a brief description of the spacecraft. We also present a preliminary analysis of comparing distance estimates of Be stars from the first Gaia data release, Gaia DR1, and Hipparcos mission. From our analysis, we confirm that Gaia stands out as a promising mission in terms of the distance measurements when compared to Hipparcos, particularly for distances greater than 1 kpc

An innate pathogen sensing strategy involving ubiquitination of bacterial surface proteins.

Sensing of pathogens by ubiquitination is a critical arm of cellular immunity. However, universal ubiquitination targets on microbes remain unidentified. Here, using in vitro, ex vivo, and in vivo studies, we identify the first protein-based ubiquitination substrates on phylogenetically diverse bacteria by unveiling a strategy that uses recognition of degron-like motifs. Such motifs form a new class of intra-cytosolic pathogen-associated molecular patterns (PAMPs). Their incorporation enabled recognition of nonubiquitin targets by host ubiquitin ligases. We find that SCFFBW7 E3 ligase, supported by the regulatory kinase, glycogen synthase kinase 3β, is crucial for effective pathogen detection and clearance. This provides a mechanistic explanation for enhanced risk of infections in patients with chronic lymphocytic leukemia bearing mutations in F-box and WD repeat domain containing 7 protein. We conclude that exploitation of this generic pathogen sensing strategy allows conservation of host resources and boosts antimicrobial immunity

IL-13Rα2 Regulates the IL-13/IFN-γ Balance during Innate Lymphoid Cell and Dendritic Cell Responses to Pox Viral Vector-Based Vaccination

We have shown that manipulation of IL-13 and STAT6 signaling at the vaccination site can lead to different innate lymphoid cell (ILC)/dendritic cell (DC) recruitment, resulting in high avidity/poly-functional T cells and effective antibody differentiation. Here we show that permanent versus transient blockage of IL-13 and STAT6 at the vaccination site can lead to unique ILC-derived IL-13 and IFN-γ profiles, and differential IL-13Rα2, type I and II IL-4 receptor regulation on ILC. Specifically, STAT6−/− BALB/c mice given fowl pox virus (FPV) expressing HIV antigens induced elevated ST2/IL-33R+ ILC2-derived IL-13 and reduced NKp46+/− ILC1/ILC3-derived IFN-γ expression, whilst the opposite (reduced IL-13 and elevated IFN-γ expression) was observed during transient inhibition of STAT6 signaling in wild type BALB/c mice given FPV-HIV-IL-4R antagonist vaccination. Interestingly, disruption/inhibition of STAT6 signaling considerably impacted IL-13Rα2 expression by ST2/IL-33R+ ILC2 and NKp46− ILC1/ILC3, unlike direct IL-13 inhibition. Consistently with our previous findings, this further indicated that inhibition of STAT6 most likely promoted IL-13 regulation via IL-13Rα2. Moreover, the elevated ST2/IL-33R+ IL-13Rα2+ lung ILC2, 24 h post FPV-HIV-IL-4R antagonist vaccination was also suggestive of an autocrine regulation of ILC2-derived IL-13 and IL-13Rα2, under certain conditions. Knowing that IL-13 can modulate IFN-γ expression, the elevated expression of IFN-γR on lung ST2/IL-33R+ ILC2 provoked the notion that there could also be inter-regulation of lung ILC2-derived IL-13 and NKp46− ILC1/ILC3-derived IFN-γ via their respective receptors (IFN-γR and IL-13Rα2) at the lung mucosae early stages of vaccination. Intriguingly, under different IL-13 conditions differential regulation of IL-13/IL-13Rα2 on lung DC was also observed. Collectively these findings further substantiated that IL-13 is the master regulator of, not only DC, but also different ILC subsets at early stages of viral vector vaccination, and responsible for shaping the downstream adaptive immune outcomes. Thus, thoughtful selection of vaccine strategies/adjuvants that can manipulate IL-13Rα2, and STAT6 signaling at the ILC/DC level may prove useful in designing more efficacious vaccines against different/chronic pathogens

The pressures of surgicel® in cardiac surgery

Surgicel® is bioabsorbable hemostatic mesh, frequently packed around oozing surgical bed. We report two morbidities due to it. Following transannular patch repair for Fallot′s tetralogy, Surgicel® was packed around distal main pulmonary artery. Echocardiography in the intensive care unit (ICU) showed right ventricular dysfunction due to extrinsic obstruction and complete occlusion of left pulmonary artery (LPA) flows. Another patient with arterial switch operation had postoperative fibrillatory cardiac arrest, needing resuscitation with internal cardiac massage. The arrest was triggered by coronary ischemia due to periaortic compression. Both instances were caused by hygroscopic nature of Surgicel®, which absorbed blood, swelled, and compressed the luminal tissues

The bubbling Milky Way: An overview of infrared bubbles in our galaxy

Infrared bubbles are cavity-like structures formed around OB-type star(s) or star clusters. They are detected primarily at mid-infrared wavelengths. They usually enclose ionized gas and hot dust, composed of very small grains. A combination of thermal pressure of the expanding HIIregion, powerful stellar winds, and radiation pressure associated with massive stars contribute to the formation of a bubble. Expanding bubbles could trigger star formation, either via the collect and collapse process or radiatively driven implosion. This can further provide a pathway for understanding the aspects related to triggered star formation. This article provides a brief overview on infrared bubbles, their association with the HIIregion,the massive and young stellar objects they enclose, and the mechanisms of triggered star formation when they expand to the interstellar medium. As a representative example, we present a multiwavelength investigation of the northern infrared bubble CN71. The physical environment of the bubble CN71 is investigated using Spitzer data. We have detected 29 Class I/II YSOs and 459 Class III YSOs by NIR-MIR photometric analysis. We have also detected the presence of 5 OB-type stars within the bubble boundary. Using the Gaia EDR3, we estimated the distance to the bubble to be 1.6 kpc. Our preliminary analysis suggests that CN71 shows the signature of triggered star formation

Alternative and Natural Therapies for Acute Lung Injury and Acute Respiratory Distress Syndrome

Introduction. Acute respiratory distress syndrome (ARDS) is a complex clinical syndrome characterized by acute inflammation, microvascular damage, and increased pulmonary vascular and epithelial permeability, frequently resulting in acute respiratory failure and death. Current best practice for ARDS involves “lung-protective ventilation,” which entails low tidal volumes and limiting the plateau pressures in mechanically ventilated patients. Although considerable progress has been made in understanding the pathogenesis of ARDS, little progress has been made in the development of specific therapies to combat injury and inflammation. Areas Covered. In recent years, several natural products have been studied in experimental models and have been shown to inhibit multiple inflammatory pathways associated with acute lung injury and ARDS at a molecular level. Because of the pleiotropic effects of these agents, many of them also activate antioxidant pathways through nuclear factor erythroid-related factor 2, thereby targeting multiple pathways. Several of these agents are prescribed for treatment of inflammatory conditions in the Asian subcontinent and have shown to be relatively safe. Expert Commentary. Here we review natural remedies shown to attenuate lung injury and inflammation in experimental models. Translational human studies in patients with ARDS may facilitate treatment of this devastating disease