Immunoglobulins in COVID-19 pneumonia: from the acute phase to the recovery phase.

BACKGROUND: COVID-19 pneumonia causes hyperinflammatory response that culminates in acute respiratory syndrome (ARDS) related to increased multiorgan dysfunction and mortality risk. Antiviral-neutralizing immunoglobulins production reflect the host humoral status and illness severity, and thus, immunoglobulin (Ig) circulating levels could be evidence of COVID-19 prognosis. METHODS: The relationship among circulating immunoglobulins (IgA, IgG, IgM) and COVID-19 pneumonia was evaluated using clinical information and blood samples in a COVID-19 cohort composed by 320 individuals recruited during the acute phase and followed up to 4 to 8 weeks (n = 252) from the Spanish first to fourth waves. RESULTS: COVID-19 pneumonia development depended on baseline Ig concentrations. Circulating IgA levels together with clinical features at acute phase was highly associated with COVID-19 pneumonia development. IgM was positively correlated with obesity (ρb = 0.156, P = 0.020), dyslipemia (ρb = 0.140, P = 0.029), COPD (ρb = 0.133, P = 0.037), cancer (ρb = 0.173, P = 0.007) and hypertension (ρb = 0.148, P = 0.020). Ig concentrations at recovery phase were related to COVID-19 treatments. CONCLUSIONS: Our results provide valuable information on the dynamics of immunoglobulins upon SARS-CoV-2 infection or other similar viruses.

TGFß/activin-dependent activation of Torso controls the timing of the metamorphic transition in the red flour beetle Tribolium castaneum.

Understanding the mechanisms governing body size attainment during animal development is of paramount importance in biology. In insects, a crucial phase in determining body size occurs at the larva-pupa transition, marking the end of the larval growth period. Central to this process is the attainment of the threshold size (TS), a critical developmental checkpoint that must be reached before the larva can undergo metamorphosis. However, the intricate molecular mechanisms by which the TS orchestrates this transition remain poor understood. In this study, we investigate the role of the interaction between the Torso and TGFß/activin signaling pathways in regulating metamorphic timing in the red flour beetle, Tribolium castaneum. Our results show that Torso signaling is required specifically during the last larval instar and that its activation is mediated not only by the prothoracicotropic hormone (Tc-Ptth) but also by Trunk (Tc-Trk), another ligand of the Tc-Torso receptor. Interestingly, we show that while Tc-Torso activation by Tc-Ptth determines the onset of metamorphosis, Tc-Trk promotes growth during the last larval stage. In addition, we found that the expression of Tc-torso correlates with the attainment of the TS and the decay of juvenile hormone (JH) levels, at the onset of the last larval instar. Notably, our data reveal that activation of TGFß/activin signaling pathway at the TS is responsible for repressing the JH synthesis and inducing Tc-torso expression, initiating metamorphosis. Altogether, these findings shed light on the pivotal involvement of the Ptth/Trunk/Torso and TGFß/activin signaling pathways as critical regulatory components orchestrating the TS-driven metamorphic initiation, offering valuable insights into the mechanisms underlying body size determination in insects.

Mitochondrial dysfunction, lipids metabolism, and amino acid biosynthesis are key pathways for COVID-19 recovery.

The metabolic alterations caused by SARS-CoV-2 infection reflect disease progression. To analyze molecules involved in these metabolic changes, a multiomics study was performed using plasma from 103 patients with different degrees of COVID-19 severity during the evolution of the infection. With the increased severity of COVID-19, changes in circulating proteomic, metabolomic, and lipidomic profiles increased. Notably, the group of severe and critical patients with high HRG and ChoE (20:3) and low alpha-ketoglutaric acid levels had a high chance of unfavorable disease evolution (AUC = 0.925). Consequently, patients with the worst prognosis presented alterations in the TCA cycle (mitochondrial dysfunction), lipid metabolism, amino acid biosynthesis, and coagulation. Our findings increase knowledge regarding how SARS-CoV-2 infection affects different metabolic pathways and help in understanding the future consequences of COVID-19 to identify potential therapeutic targets.

Multi-omics in HIV: searching insights to understand immunological non-response in PLHIV.

Antiretroviral therapy (ART) induces persistent suppression of HIV-1 replication and gradual recovery of T-cell counts, and consequently, morbidity and mortality from HIV-related illnesses have been significantly reduced. However, in approximately 30% of people living with HIV (PLHIV) on ART, CD4+ T-cell counts fail to normalize despite ART and complete suppression of HIV viral load, resulting in severe immune dysfunction, which may represent an increased risk of clinical progression to AIDS and non-AIDS events as well as increased mortality. These patients are referred to as "immune inadequate responders", "immunodiscordant responders" or "immune nonresponders (INR)". The molecular mechanisms underlying poor CD4+ T-cell recovery are still unclear. In this sense, the use of omics sciences has shed light on possible factors involved in the activity and metabolic dysregulation of immune cells during the failure of CD4+ T-cell recovery in INR. Moreover, identification of key molecules by omics approaches allows for the proposal of potential biomarkers or therapeutic targets to improve CD4+ T-cell recovery and the quality of life of these patients. Hence, this review aimed to summarize the information obtained through different omics concerning the molecular factors and pathways associated with the INR phenotype to better understand the complexity of this immunological status in HIV infection.

Fucosylated N-glycans as early biomarkers of COVID-19 severity.

Background: The pathological mechanisms of SARS-CoV-2 in humans remain unclear and the unpredictability of COVID-19 progression may be attributed to the absence of biomarkers that contribute to the prognosis of this disease. Therefore, the discovery of biomarkers is needed for reliable risk stratification and to identify patients who are more likely to progress to a critical stage. Methods: Aiming to identify new biomarkers we analysed N-glycan traits in plasma from 196 patients with COVID-19. Samples were classified into three groups according to their severity (mild, severe and critical) and obtained at diagnosis (baseline) and at 4 weeks of follow-up (postdiagnosis), to evaluate their behaviour through disease progression. N-glycans were released with PNGase F and labelled with Rapifluor-MS, followed by their analysis by LC-MS/MS. The Simglycan structural identification tool and Glycostore database were employed to predict the structure of glycans. Results: We determined that plasma from SARS-CoV-2-infected patients display different N-glycosylation profiles depending on the disease severity. Specifically, levels of fucosylation and galactosylation decreased with increasing severity and Fuc1Hex5HexNAc5 was identified as the most suitable biomarker to stratify patients at diagnosis and distinguish mild from critical outcomes. Conclusion: In this study we explored the global plasma glycosignature, reflecting the inflammatory state of the organs during the infectious disease. Our findings show the promising potential of glycans as biomarkers of COVID-19 severity.

Antagonistic role of the BTB-zinc finger transcription factors Chinmo and Broad-Complex in the juvenile/pupal transition and in growth control.

During development, the growing organism transits through a series of temporally regulated morphological stages to generate the adult form. In humans, for example, development progresses from childhood through to puberty and then to adulthood, when sexual maturity is attained. Similarly, in holometabolous insects, immature juveniles transit to the adult form through an intermediate pupal stage when larval tissues are eliminated and the imaginal progenitor cells form the adult structures. The identity of the larval, pupal, and adult stages depends on the sequential expression of the transcription factors chinmo, Br-C, and E93. However, how these transcription factors determine temporal identity in developing tissues is poorly understood. Here, we report on the role of the larval specifier chinmo in larval and adult progenitor cells during fly development. Interestingly, chinmo promotes growth in larval and imaginal tissues in a Br-C-independent and -dependent manner, respectively. In addition, we found that the absence of chinmo during metamorphosis is critical for proper adult differentiation. Importantly, we also provide evidence that, in contrast to the well-known role of chinmo as a pro-oncogene, Br-C and E93 act as tumour suppressors. Finally, we reveal that the function of chinmo as a juvenile specifier is conserved in hemimetabolous insects as its homolog has a similar role in Blatella germanica. Taken together, our results suggest that the sequential expression of the transcription factors Chinmo, Br-C and E93 during larva, pupa an adult respectively, coordinate the formation of the different organs that constitute the adult organism.

Egg, larva, pupa, adult: the life of many insects is structured around these four well-defined stages of development. After hatching, the larva grows until it reaches a certain size; when the right conditions are met, it then becomes a pupa and metamorphoses into an adult. Most larval cells die during metamorphosis; only a group known as imaginal cells survives, dividing and maturing to create pupal and adult tissues. Each of these developmental steps are linked to a particular genetic program deployed in response to a single stage-specifying gene. For instance, the activation of the Br-C gene triggers the transition from larva to pupa, while E93 initiates the transformation of the pupa into an adult. However, which stage-specifying gene controls larval identity remains unclear. Recent studies suggest that in fruit flies, a gene known as chinmo could be playing this role. In response, Chafino et al. explored how chinmo shapes the development of fruit fly larvae. The experiments showed that chinmo is activated in the juvenile stage, and that it is required for the larvae to grow properly and for larval and imaginal tissues to form. Conversely, it must be switched off for the insect to become a pupa and then an adult. Further work suggested that the role of chinmo as a larval specifier could have emerged early in insect evolution. Moreover, Chafino et al. revealed that chinmo could repress Br-C, an important characteristic since stage-specifying genes usually switch on sequentially by regulating each other. A closer look suggested that, in imaginal cells, chinmo promotes development by inhibiting Br-C; in larval cells, however, chinmo not only has a Brc-repressing role but it is also necessary for larval cells to grow. Additional experiments exploring the role of the stage-specifying genes in tumor formation showed that chinmo promotes cells proliferation while Br-C and E93 had tumor-suppressing properties. Overall, the work by Chafino et al. sheds new light on the genetic control of insect development, while also potentially providing a new perspective on how genes related to chinmo and Br-C contribute to the emergence of human cancers.

Activation of EGFR signaling by Tc-Vein and Tc-Spitz regulates the metamorphic transition in the red flour beetle Tribolium castaneum.

Animal development relies on a sequence of specific stages that allow the formation of adult structures with a determined size. In general, juvenile stages are dedicated mainly to growth, whereas last stages are devoted predominantly to the maturation of adult structures. In holometabolous insects, metamorphosis marks the end of the growth period as the animals stops feeding and initiate the final differentiation of the tissues. This transition is controlled by the steroid hormone ecdysone produced in the prothoracic gland. In Drosophila melanogaster different signals have been shown to regulate the production of ecdysone, such as PTTH/Torso, TGFß and Egfr signaling. However, to which extent the roles of these signals are conserved remains unknown. Here, we study the role of Egfr signaling in post-embryonic development of the basal holometabolous beetle Tribolium castaneum. We show that Tc-Egfr and Tc-pointed are required to induced a proper larval-pupal transition through the control of the expression of ecdysone biosynthetic genes. Furthermore, we identified an additional Tc-Egfr ligand in the Tribolium genome, the neuregulin-like protein Tc-Vein (Tc-Vn), which contributes to induce larval-pupal transition together with Tc-Spitz (Tc-Spi). Interestingly, we found that in addition to the redundant role in the control of pupa formation, each ligand possesses different functions in organ morphogenesis. Whereas Tc-Spi acts as the main ligand in urogomphi and gin traps, Tc-Vn is required in wings and elytra. Altogether, our findings show that in Tribolium, post-embryonic Tc-Egfr signaling activation depends on the presence of two ligands and that its role in metamorphic transition is conserved in holometabolous insects.

How stage identity is established in insects: the role of the Metamorphic Gene Network.

Proper formation of adult insects requires the integration of spatial and temporal regulatory axes. Whereas spatial information confers identity to each tissue, organ and appendage, temporal information specifies at which stage of development the animal is. Regardless of the type of post-embryonic development, either hemimetabolous or holometabolous, temporal specificity is achieved through interactions between the temporal identity genes Kr-h1, E93 and Br-C, whose sequential expression is controlled by the two major developmental hormones, 20-hydroxyecdysone and Juvenile hormone. Given the intimate regulatory connection between these three factors to specify life stage identity, we dubbed the regulatory axis that comprises these genes as the Metamorphic Gene Network (MGN). In this review, we survey the molecular mechanisms underlying the control by the MGN of stage identity and progression in hemimetabolous and holometabolous insects.

Photoperiod and temperature separately regulate nymphal development through JH and insulin/TOR signaling pathways in an insect.

Insects living in the temperate zone enter a physiological state of arrested or slowed development to overcome an adverse season, such as winter. Developmental arrest, called diapause, occurs at a species-specific developmental stage, and embryonic and pupal diapauses have been extensively studied in mostly holometabolous insects. Some other insects overwinter in the nymphal stage with slow growth for which the mechanism is poorly understood. Here, we show that this nymphal period of slow growth is regulated by temperature and photoperiod through separate pathways in the cricket Modicogryllus siamensis The former regulates the growth rate, at least in part, through the insulin / target of rapamycin (TOR) signaling pathway. Lower temperature down-regulates the expression of insulin-like peptide (Ms'Ilp) and Target of rapamycin (Ms'Tor) genes to slow down the growth rate without affecting the number of molts. The latter regulates the number of molts independent of temperature. Short days increase the number of molts through activation of the juvenile hormone (JH) pathway and down-regulation of myoglianin (Ms'myo), a member of the TGFß family, which induces adult metamorphosis. In contrast, long days regulate Ms'myo expression to increase during the fifth to sixth instar to initiate adult metamorphosis. When Ms'myo expression is suppressed, juvenile hormone O-methyl transferase (Ms'jhamt) was up-regulated and increased molts to prolong the nymphal period even under long-day conditions. The present findings suggested that the photoperiod regulated Ms'myo, and the JH signaling pathway and the temperature-controlled insulin/TOR pathway cooperated to regulate nymphal development for overwintering to achieve seasonal adaptation of the life cycle in M. siamensis.

Target of rapamycin (TOR) determines appendage size during pupa formation of the red flour beetle Tribolium castaneum.

The adult body size is species-specific and controlled by complex interactions between hormones and the IIS/TOR pathway. To analyze the role of target of rapamycin (TOR) in the growth and development of the insect, expression levels of TOR were silenced in the model and pest insect red flour beetle, Tribolium castaneum. Injection of dsRNA into the last larval instar decreased pupal mass and size, while the amount of food intake by the larvae was not affected. These results place TcTOR downstream of nutrition as a transducer for nutritional signals to increase larval growth. In addition, TcTOR-silencing notably decreased the size of the adult appendages. Analysis of the wings and elytra revealed a decrease in cell size and number of these appendages in the TcTOR-silenced insects. This reduction in size was correlated with a decrease of transcriptional levels of marker genes controlling the cell cycle. Altogether, these results suggest a pivotal role for TcTOR in integrating nutritional signals and regulation of body and appendages growth.

Upregulation of E93 Gene Expression Acts as the Trigger for Metamorphosis Independently of the Threshold Size in the Beetle Tribolium castaneum.

Body size in holometabolous insects is determined by the size at which the juvenile larva undergoes metamorphosis to the pupal stage. To undergo larva-pupa transition, larva must reach a critical developmental checkpoint, the threshold size (TS); however, the molecular mechanisms through which the TS cues this transition remain to be fully characterized. Here, we use the flour beetle Tribolium castaneum to characterize the molecular mechanisms underlying entry into metamorphosis. We found that T. castaneum reaches a TS at the beginning of the last larval instar, which is associated with the downregulation of TcKr-h1 and the upregulation of TcE93 and TcBr-C. Unexpectedly, we found that while there is an association between TS and TcE93 upregulation, it is the latter that constitutes the molecular trigger for metamorphosis initiation. In light of our results, we evaluate the interactions that control the larva-pupa transition and suggest alternative models.

The Occurrence of the Holometabolous Pupal Stage Requires the Interaction between E93, Krüppel-Homolog 1 and Broad-Complex.

Complete metamorphosis (Holometaboly) is a key innovation that underlies the spectacular success of holometabolous insects. Phylogenetic analyses indicate that Holometabola form a monophyletic group that evolved from ancestors exhibiting hemimetabolous development (Hemimetaboly). However, the nature of the changes underlying this crucial transition, including the occurrence of the holometabolan-specific pupal stage, is poorly understood. Using the holometabolous beetle Tribolium castaneum as a model insect, here we show that the transient up-regulation of the anti-metamorphic Krüppel-homolog 1 (TcKr-h1) gene at the end of the last larval instar is critical in the formation of the pupa. We find that depletion of this specific TcKr-h1 peak leads to the precocious up-regulation of the adult-specifier factor TcE93 and, hence, to a direct transformation of the larva into the adult form, bypassing the pupal stage. Moreover, we also find that the TcKr-h1-dependent repression of TcE93 is critical to allow the strong up-regulation of Broad-complex (TcBr-C), a key transcription factor that regulates the correct formation of the pupa in holometabolous insects. Notably, we show that the genetic interaction between Kr-h1 and E93 is also present in the penultimate nymphal instar of the hemimetabolous insect Blattella germanica, suggesting that the evolution of the pupa has been facilitated by the co-option of regulatory mechanisms present in hemimetabolan metamorphosis. Our findings, therefore, contribute to the molecular understanding of insect metamorphosis, and indicate the evolutionary conservation of the genetic circuitry that controls hemimetabolan and holometabolan metamorphosis, thereby shedding light on the evolution of complete metamorphosis.

Evolution of SUMO Function and Chain Formation in Insects.

SUMOylation, the covalent binding of Small Ubiquitin-like Modifier (SUMO) to target proteins, is a posttranslational modification that regulates critical cellular processes in eukaryotes. In insects, SUMOylation has been studied in holometabolous species, particularly in the dipteran Drosophila melanogaster, which contains a single SUMO gene (smt3). This has led to the assumption that insects contain a single SUMO gene. However, the analysis of insect genomes shows that basal insects contain two SUMO genes, orthologous to vertebrate SUMO1 and SUMO2/3. Our phylogenetical analysis reveals that the SUMO gene has been duplicated giving rise to SUMO1 and SUMO2/3 families early in Metazoan evolution, and that later in insect evolution the SUMO1 gene has been lost after the Hymenoptera divergence. To explore the consequences of this loss, we have examined the characteristics and different biological functions of the two SUMO genes (SUMO1 and SUMO3) in the hemimetabolous cockroach Blattella germanica and compared them with those of Drosophila Smt3. Here, we show that the metamorphic role of the SUMO genes is evolutionary conserved in insects, although there has been a regulatory switch from SUMO1 in basal insects to SUMO3 in more derived ones. We also show that, unlike vertebrates, insect SUMO3 proteins cannot form polySUMO chains due to the loss of critical lysine residues within the N-terminal part of the protein. Furthermore, the formation of polySUMO chains by expression of ectopic human SUMO3 has a deleterious effect in Drosophila. These findings contribute to the understanding of the functional consequences of the evolution of SUMO genes.