Role of glutathionylation in infection and inflammation

Glutathionylation, that is, the formation of mixed disulfides between protein cysteines and glutathione (GSH) cysteines, is a reversible post-translational modification catalyzed by dierent cellular oxidoreductases, by which the redox state of the cell modulates protein function. So far, most studies on the identification of glutathionylated proteins have focused on cellular proteins, including proteins involved in host response to infection, but there is a growing number of reports showing that microbial proteins also undergo glutathionylation, with modification of their characteristics and functions. In the present review, we highlight the signaling role of GSH through glutathionylation, particularly focusing on microbial (viral and bacterial) glutathionylated proteins (GSSPs) and host GSSPs involved in the immune/inflammatory response to infection; moreover, we discuss the biological role of the process in microbial infections and related host responses

Glutathione increase by the n-butanoyl glutathione derivative (GSH-C4) inhibits viral replication and induces a predominant Th1 immune profile in old mice infected with influenza virus

During aging, glutathione (GSH) content declines and the immune system undergoes a deficiency in the induction of Th1 response. Reduced secretion of Th1 cytokines, which is associated with GSH depletion, could weaken the host defenses against viral infections. We first evaluated the concentration of GSH and cysteine in organs of old mice; then, the effect of the administration of the N-butanoyl GSH derivative (GSH-C4) on the response of aged mice infected with influenza A PR8/H1N1 virus was studied through the determination of GSH concentration in organs, lung viral titer, IgA and IgG1/IgG2a production and Th1/Th2 cytokine profile. Old mice had lower GSH than young mice in organs. Also the gene expression of endoplasmic reticulum (ER) stress markers involved in GSH metabolism and folding of proteins, i.e. Nrf2 and PDI, was reduced. Following infection, GSH content remained low and neither infection nor GSH-C4 treatment affected Nrf2 expression. In contrast, PDI expression was upregulated during infection and appeared counterbalanced by GSH-C4. Moreover, the treatment with GSH-C4 increased GSH content in organs, reduced viral replication and induced a predominant Th1 response. In conclusion, GSH-C4 treatment could be used in the elderly to contrast influenza virus infection by inducing immune response, in particular the Th1 profile

GSH-C4 acts as anti-inflammatory drug in different models of canonical and cell autonomous inflammation through NFκB inhibition

An imbalance in GSH/GSSG ratio represents a triggering event in pro-inflammatory cytokine production and inflammatory response. However, the molecular mechanism(s) through which GSH regulates macrophage and cell autonomous inflammation remains not deeply understood. Here, we investigated the effects of a derivative of GSH, the N-butanoyl glutathione (GSH-C4), a cell permeable compound, on lipopolisaccharide (LPS)-stimulated murine RAW 264.7 macrophages, and human macrophages. LPS alone induces a significant production of pro-inflammatory cytokines, such as IL-1β, IL-6, and TNF-α and a significant decrement of GSH content. Such events were significantly abrogated by treatment with GSH-C4. Moreover, GSH-C4 was highly efficient in buffering cell autonomous inflammatory status of aged C2C12 myotubes and 3T3-L1 adipocytes by suppressing the production of pro-inflammatory cytokines. We found that inflammation was paralleled by a strong induction of the phosphorylated form of NFκB, which translocates into the nucleus; a process that was also efficiently inhibited by the treatment with GSH-C4. Overall, the evidence suggests that GSH decrement is required for efficient activation of an inflammatory condition and, at the same time, GSH-C4 can be envisaged as a good candidate to abrogate such process, expanding the anti-inflammatory role of this molecule in chronic inflammatory states

Merkel cell polyomavirus (MCPyV) in the context of Immunosuppression. Genetic analysis of noncoding control region (NCCR) variability among a HIV-1-positive population

Background: Since limited data are available about the prevalence of Merkel cell polyomavirus (MCPyV) and the genetic variability of its noncoding control region (NCCR) in the context of immunosuppression, this study aimed to investigate the distribution of MCPyV in anatomical sites other than the skin and the behavior of NCCR among an HIV-1-positive population. Methods: Urine, plasma, and rectal swabs specimens from a cohort of 66 HIV-1-positive patients were collected and subjected to quantitative real-time polymerase chain reaction (qPCR) for MCPyV DNA detection. MCPyV-positive samples were amplified by nested PCR targeting the NCCR, and NCCRs alignment was carried out to evaluate the occurrence of mutations and to identify putative binding sites for cellular factors. Results: MCPyV DNA was detected in 10/66 urine, in 7/66 plasma, and in 23/66 rectal samples, with a median value of 5 × 102 copies/mL, 1.5 × 102 copies/mL, and 2.3 × 103 copies/mL, respectively. NCCR sequence analysis revealed a high degree of homology with the MCC350 reference strain in urine, whereas transitions, transversions, and single or double deletions were observed in plasma and rectal swabs. In these latter samples, representative GTT and GTTGA insertions were also observed. Search for putative binding sites of cellular transcription factors showed that in several strains, deletions, insertions, or single base substitutions altered the NCCR canonical configuration. Conclusions: Sequencing analysis revealed the presence of numerous mutations in the NCCR, including insertions and deletions. Whether these mutations may have an impact on the pathogenic features of the virus remains to be determined. qPCR measured on average a low viral load in the specimens analyzed, with the exception of those with the GTTGA insertion

Redox proteomics of the inflammatory secretome identifies a common set of redoxins and other glutathionylated proteins released in inflammation, influenza virus infection and oxidative stress

Protein cysteines can form transient disulfides with glutathione (GSH), resulting in the production of glutathionylated proteins, and this process is regarded as a mechanism by which the redox state of the cell can regulate protein function. Most studies on redox regulation of immunity have focused on intracellular proteins. In this study we have used redox proteomics to identify those proteins released in glutathionylated form by macrophages stimulated with lipopolysaccharide (LPS) after pre-loading the cells with biotinylated GSH. Of the several proteins identified in the redox secretome, we have selected a number for validation. Proteomic analysis indicated that LPS stimulated the release of peroxiredoxin (PRDX) 1, PRDX2, vimentin (VIM), profilin1 (PFN1) and thioredoxin 1 (TXN1). For PRDX1 and TXN1, we were able to confirm that the released protein is glutathionylated. PRDX1, PRDX2 and TXN1 were also released by the human pulmonary epithelial cell line, A549, infected with influenza virus. The release of the proteins identified was inhibited by the anti-inflammatory glucocorticoid, dexamethasone (DEX), which also inhibited tumor necrosis factor (TNF)-α release, and by thiol antioxidants (N-butanoyl GSH derivative, GSH-C4, and N-acetylcysteine (NAC), which did not affect TNF-α production. The proteins identified could be useful as biomarkers of oxidative stress associated with inflammation, and further studies will be required to investigate if the extracellular forms of these proteins has immunoregulatory functions

QFQ: Efficient Packet Scheduling With Tight Guarantees

Packet scheduling, together with classification, is one of the most expensive processing steps in systems providing tight bandwidth and delay guarantees at high packet rates. Schedulers with near-optimal service guarantees and ${ O}({1})$ time complexity have been proposed in the past, using techniques such as timestamp rounding and flow grouping to keep their execution time small. However, even the two best proposals in this family have a per-packet cost component that is linear either in the number of groups or in the length of the packet being transmitted. Furthermore, no studies are available on the actual execution time of these algorithms. In this paper we make two contributions. First, we present Quick Fair Queueing (QFQ), a new ${ O}({ 1})$ scheduler that provides near-optimal guarantees and is the first to achieve that goal with a truly constant cost also with respect to the number of groups and the packet length. The QFQ algorithm has no loops and uses very simple instructions and data structures that contribute to its speed of operation. Second, we have developed production-quality implementations of QFQ and of its closest competitors, which we use to present a detailed comparative performance analysis of the various algorithms. Experiments show that QFQ fulfills our expectations, outperforming the other algorithms in the same class. In absolute terms, even on a low-end workstation, QFQ takes about 110 ns for an enqueue()/dequeue() pair (only twice the time of DRR, but with much better service guarantees)

Re-deposited rhodoliths in the Middle Miocene hemipelagic deposits of Vitulano (Southern Apennines, Italy): Coralline assemblage characterization and related fossil traces

An integrated analysis of rhodolith assemblages and associated fossil traces (borings) found in hemipelagic Middle Miocene Orbulina marls (Vitulano area, Taburno–Camposauro area, Southern Apennines, Italy) has revealed that both the biodiversity of the constituent components and taphonomic signatures represent important aspects which allow a detailed palaeoecological and palaeoenvironmental interpretation. On the basis of shape, inner arrangement, growth forms and taxonomic coralline algal composition, two rhodolith growth stages were distinguished: (1) nucleation and growth of the rhodoliths, and (2) a final growth stage before burial. Nucleation is characterised by melobesioids and subordinately mastophoroids, with rare sporolithaceans and lithophylloids. The rhodolith growth (main increase in size) is represented by abundant melobesioids and rare to common mastophoroids; very rare sporolithaceans are also present. The final growth stage is dominated by melobesioids with rare mastophoroids and very rare sporolithaceans. Each rhodolith growth stage is characterised by a distinct suite of inner arrangement and growth form successions. Well diversified ichnocoenoeses (Gastrochaenolites, Trypanites, Meandropolydora and/or Caulostrepsis, Entobia, Uniglobites, micro-borings) related to bivalves, sponges, polychaetes, barnacles, algae, fungi, bacteria are distinguished in the inner/intermediate rhodolith growth stage, while mainly algal, fungal and bacterial microborings are present in the outer final growth stage. Rhodolith growth stages and associated ichnocoenoeses indicate significant change in the depositional setting during the rhodolith growth. In the Vitulano area, the Middle Miocene rhodolith assemblages formed in a shallow water open-shelf carbonate platform, were susceptible to exportation from their production area and then to sedimentation down to deeper water hemipelagic settings, where the rhodoliths shortly kept growth and were finally buried. Such re-deposition of unlithified or only weakly lithified (i.e. rhodoliths and intraclasts) shallow-water carbonates into deeper water settings was likely favoured by storm-generated offshore return currents rather than sediment gravity flows