Clinical Features and Mortality of COVID-19-Associated Mucormycosis: A Systematic Review and Meta-Analysis

The recent increase of COVID-19-associated mucormycosis (CAM) has been commanding global attention. However, basic epidemiologic characteristics have not firmly been established. In this systematic review and meta-analysis, we sought to determine the clinical manifestations, potential risk factors, and outcomes of CAM. Observational studies reporting CAM were searched with PubMed and EMBASE databases in January 2022. We collected data on comorbidities and treatment for COVID-19, and performed a one-group meta-analysis on the frequency of orbital exenteration procedure and mortality of CAM using a random-effect model. Fifty-one observational studies, including a total of 2,312 patients with proven CAM, were identified. Among the 51 studies, 37 were conducted in India, 8 in Egypt, and 6 in other countries. The most common comorbidity was diabetes mellitus (82%). While 57% required oxygenation, 77% received systemic corticosteroids. Among CAM, 97% were rhino-orbital-cerebral (ROCM), and 2.7% were pulmonary mucormycosis. Usual presentations were headache (54%), periorbital swelling/pain (53%), facial swelling/pain (43%), ophthalmoplegia (42%), proptosis (41%), and nasal discharge/congestion (36%). Regarding the outcomes, orbital exenteration was performed in 17% (95% CI: 12–21%, I²?=?83%) of the COVID-19-associated ROCM patients. The mortality of CAM was 29% (95% CI; 22–36%, I²?=?92%). In conclusion, this systematic review and meta-analysis indicated that the most prevalent type of CAM was ROCM, and most CAM patients had diabetes mellitus and received systemic glucocorticoids. Clinicians in the endemic areas should have a high index of suspicion for this invasive fungal complication of COVID-19 when a diabetic patient who received high-dose systemic glucocorticoids developed rhino-orbital symptoms.

     

KONJAC1 and 2 Are Key Factors for GDP-Mannose Generation and Affect l-Ascorbic Acid and Glucomannan Biosynthesis in Arabidopsis

Humans are unable to synthesize l-ascorbic acid (AsA), yet it is required as a cofactor in many critical biochemical reactions. The majority of human dietary AsA is obtained from plants. In Arabidopsis thaliana, a GDP-mannose pyrophosphorylase (GMPP), VITAMIN C DEFECTIVE1 (VTC1), catalyzes a rate-limiting step in AsA synthesis: the formation of GDP-Man. In this study, we identified two nucleotide sugar pyrophosphorylase-like proteins, KONJAC1 (KJC1) and KJC2, which stimulate the activity of VTC1. The kjc1kjc2 double mutant exhibited severe dwarfism, indicating that KJC proteins are important for growth and development. The kjc1 mutation reduced GMPP activity to 10% of wild-type levels, leading to a 60% reduction in AsA levels. On the contrary, overexpression of KJC1 significantly increased GMPP activity. The kjc1 and kjc1kjc2 mutants also exhibited significantly reduced levels of glucomannan, which is also synthesized from GDP-Man. Recombinant KJC1 and KJC2 enhanced the GMPP activity of recombinant VTC1 in vitro, while KJCs did not show GMPP activity. Yeast two-hybrid assays suggested that the stimulation of GMPP activity occurs via interaction of KJCs with VTC1. These results suggest that KJCs are key factors for the generation of GDP-Man and affect AsA level and glucomannan accumulation through the stimulation of VTC1 GMPP activity.     

A novel β-loop scaffold of phage-displayed peptides for highly specific affinities

Loop peptides stabilized by two β-strands were used as a scaffold for a phage displayed peptide library. Affinity-based screening for insulin provided peptides, which showed affinity constants of 10(5) M(-1) order for insulin over 100 times greater than their affinity for the structurally similar insulin-like growth factor 1. The results suggested that the scaffold offers a powerful tool for generating and screening peptides as ligands for drugs and biologics.     

Symbiotic rhizobium and nitric oxide induce gene expression of non-symbiotic hemoglobin in Lotus japonicus

We characterized the expression profiles of LjHb1 and LjHb2, non-symbiotic hemoglobin (non-sym-Hb) genes of Lotus japonicus. Although LjHb1 and LjHb2 showed 77% homology in their cDNA sequences, LjHb2 is located in a unique position in the phylogenetic tree of plant Hbs. The 5'-upstream regions of both genes contain the motif AAAGGG at a position similar to that in promoters of other non-sym-Hb genes. Expression profiles obtained by using quantitative RT-PCR showed that LjHb1 and LjHb2 were expressed in all tissues of mature plants, and expression was enhanced in mature root nodules. LjHb1 was strongly induced under both hypoxic and cold conditions, and by the application of nitric oxide (NO) donor, whereas LjHb2 was induced only by the application of sucrose. LjHb1 was also induced transiently by the inoculation with the symbiotic rhizobium Mesorhizobium loti MAFF303099. Observations using fluorescence microscopy revealed the induction of LjHb1 expression corresponded to the generation of NO. These results suggest that non-sym-Hb and NO have important roles in stress adaptation and in the early stage of legume-rhizobium symbiosis.     

Hemocyanin in the exoskeleton of crustaceans: enzymatic properties and immunolocalization

We investigated the enzymatic properties and immunohistochemical localization of cuticular hemocyanin, a known oxygen transporter in the prawn Penaeus japonicus. The molecular weight of hemocyanin purified from the cuticle was estimated to be 67-77 k using SDS-PAGE, and the purified protein was effectively converted into a phenoloxidase-like enzyme by an SDS-treatment. The activated enzyme catalyzed the o-hydroxylation of monophenols and the oxidation of o-diphenols and was inhibited by typical inhibitors of phenoloxidase. These characteristics were nearly identical to the enzymatic properties of hemolymph hemocyanin. Immunological detection showed a diffuse distribution of hemocyanin over the exocuticle and endocuticle, and a higher signal level was observed in the latter. Based on these results, roles of hemocyanin in various physiological processes such as immune response and sclerotization of the cuticle were discussed.     

Dynamin and the actin cytoskeleton cooperatively regulate plasma membrane invagination by BAR and F-BAR proteins

Cell membranes undergo continuous curvature changes as a result of membrane trafficking and cell motility. Deformations are achieved both by forces extrinsic to the membrane as well as by structural modifications in the bilayer or at the bilayer surface that favor the acquisition of curvature. We report here that a family of proteins previously implicated in the regulation of the actin cytoskeleton also have powerful lipid bilayer-deforming properties via an N-terminal module (F-BAR) similar to the BAR domain. Several such proteins, like a subset of BAR domain proteins, bind to dynamin, a GTPase implicated in endocytosis and actin dynamics, via SH3 domains. The ability of BAR and F-BAR domain proteins to induce tubular invaginations of the plasma membrane is enhanced by disruption of the actin cytoskeleton and is antagonized by dynamin. These results suggest a close interplay between the mechanisms that control actin dynamics and those that mediate plasma membrane invagination and fission.     

An axonemal dynein particularly important for flagellar movement at high viscosity. Implications from a new Chlamydomonas mutant deficient in the dynein heavy chain gene DHC9

Ciliary and flagellar axonemes contain multiple inner arm dyneins of which the functional difference is largely unknown. In this study, a Chlamydomonas mutant, ida9, lacking inner arm dynein c was isolated and shown to carry a mutation in the DHC9 dynein heavy chain gene. The cDNA sequence of DHC9 was determined, and its information was used to show that >80% of it is lost in the mutant. Electron microscopy and image analysis showed that the ida9 axoneme lacked electron density near the base of the S2 radial spoke, indicating that dynein c localizes to this site. The mutant ida9 swam only slightly slower than the wild type in normal media. However, swimming velocity was greatly reduced when medium viscosity was modestly increased. Thus, dynein c in wild type axonemes must produce a significant force when flagella are beating in viscous media. Because motility analyses in vitro have shown that dynein c is the fastest among all the inner arm dyneins, we can regard this dynein as a fast yet powerful motor.     

Design and expression of cysteine-bearing hydrophobic polypeptides and their self-assembling properties with bacteriochlorophyll a derivatives as a mimic of bacterial photosynthetic antenna complexes. Effect of steric confinement and orientation of the polypeptides on the pigment/polypeptide assembly process

A series of cysteine-bearing hydrophobic polypeptides analogous to a light-harvesting one betapolypeptide (LH1beta) from the LH1 complex from the purple photosynthetic bacterium, Rhodobacter sphaeroides, was synthesized using an Escherichia coli expression system. The cysteine was placed in the C- or N-terminal regions of the polypeptide to investigate the influence of steric confinement and orientation of the polypeptides via disulfide linkages as they were self-assembled with zinc-substituted bacteriochlorophyll a ([Zn]-BChl a). The polypeptides were expressed as water-soluble fusion proteins with maltose-binding protein (MBP). The fusion proteins formed a subunit-type complex with the [Zn]-BChl a in an n-octyl-beta-d-glucopyranoside (OG) micellar solution regardless of the cross-links or the cleavage of the cysteines, judging from absorption, CD, and fluorescence spectra. Following treatment with trypsin, the polypeptides were detached from the MBP portion. Such trypsin-digested polypeptides formed a subunit-type LH complex at 25 degrees C, which also showed that the disulfide linkage was not crucial for the subunit formation. When a polypeptide having cysteine on the C-terminus was assembled at 4 degrees C, the Qy absorption band was remarkably red-shifted to approximately 836 nm, suggesting that the cleavage of the large MBP portion liberates the polypeptides to form the progressive type of complex similar to LH1-type complex. The trypsin-treated polypeptides bearing cysteines in both terminal regions, which are randomly cross-linked, did not form the LH1-type complex under oxidative conditions but did form the complex under reductive conditions. This observation suggests that the polypeptide orientation strongly influences the LH1-type complex formation. The progressive assembly from the subunit to the holo-LH1-type complex following cleavage of MBP portion in a lipid bilayer is also briefly discussed.     

A novel role of IL-15 in early activation of memory CD8+ CTL after reinfection

A rapid induction of effector functions in memory T cells provides rapid and intensified protection against reinfection. To determine potential roles of IL-15 in early expansion and activation of memory CD8+ T cells in secondary immune response, we examined the cell division and cytotoxicity of memory CD8+ T cells expressing OVA(257-264)/Kb-specific TCR that were transferred into IL-15-transgenic (Tg) mice, IL-15 knockout (KO) mice, or control C57BL/6 mice followed by challenge with recombinant Listeria monocytogenes expressing OVA (rLM-OVA). In vivo CTL activities and expression of granzyme B of the transferred CD8+ T cells were significantly higher in the IL-15 Tg mice but lower in the IL-15 KO mice than those in control mice at the early stage after challenge with rLM-OVA. In contrast, there was no difference in the cell division in IL-15 Tg mice and IL-15 KO mice compared with those in control mice. In vivo administration of rIL-15 conferred robust protection against reinfection via induction of granzyme B in the memory CD8+ T cells. These results suggest that IL-15 plays an important role in early activation of memory CD8+ T cells.     

A novel role of CD30/CD30 ligand signaling in the generation of long-lived memory CD8+ T cells

Memory CD8+ T cells can be divided into two subsets, central memory (T(CM)) and effector memory (T(EM)) CD8+ T cells. We found that CD30, a member of the TNFR-associated factor (TRAF)-linked TNFR superfamily, signaling is involved in differentiation of long-lived CD8+ T(CM) cells following Listeria monocytogenes infection. Although CD8+ T(EM) cells transiently accumulated in the nonlymphoid tissues of CD30 ligand (CD153-/-) mice after infection, long-lived memory CD8+ T(CM) cells were poorly generated in these mice. CCR7 mRNA expression was down-regulated in CD8+ T cells of the spleen of CD153-/- mice in vivo and the expression was up-regulated in CD8+ T(EM) cells by anti-CD30 mAb cross-linking in vitro. These results suggest that CD30/CD30 ligand signaling plays an important role in the generation of long-lived memory CD8+ T cells at least partly by triggering homing receptors for T(CM) cells.