The new coronavirus (COVID-19) causes lymphopenia. However, an interesting fact emerges when the correlation with the disease severity is examined in detail about the subsets of the lymphocytes.
A group from The University of Massachusetts Medical School etc. has focused on Innate Lymphoid Cells (ILCs) and reported an interesting correlation with the severity of COVID-19.
ILCs are lymphocytes that do not have antigen receptors and are the main biological defense mechanism in immunity in the prestage leading up to the development of acquired immunity. NK cells with cytotoxicity are also classified as ILCs. It can be said that ILCs are divided into those mainly producing cytokines and those with cytotoxicity. In this paper, ILCs are defined as cell populations excluding NK cells.
In patients with COVID-19, ILCs are reduced by 1.78 times (95% CI: 2.34–1.36) and CD16+ NK cells by 2.31 times (95% CI: 3.1–1.71) compared to healthy people.
Interestingly, it was shown that ILCs was, but not CD16+ NK cells, CD4+ T cells, or CD8+ T cells, correlated with hospitalization, and the odds ratio of hospitalization was 0.413 (95% CI: 0.197–0.724) for every 2-fold increase in ILCs. They also showed that as ILCs increased, the odds ratio of hospitalization rates decreased, duration of hospitalization were shortened, and CRP, an inflammatory marker, decreased.
This finding is likely to lead to new treatments, I feel.
In gene therapy using Adeno-associated virus (AAV), it has been suggested that there are some differences in AAV capsids in terms of tissue targeting ability, and it has been told that glycans may be involved in he AAV’s tissue targeting ability. Such arguments have been around for quite some time.
For example, the following papers are references.
Specifically, it has been reported that AAV-1 and AAV-6 bind to Sialic acid, AAV-2 binds to Heparan sulfate, and AAV-9 binds to Galatose.
But, is it true?
To this blog admin., it is a kind of unbelievable thing that capsid proteins have lectin-like functions?
A group from Medical University of South Carolina etc. has reported their findings on glycan markers for pancreatic duct adenocarcinoma.
In order to study the glycan markers of pancreatic duct adenocarcinoma in detail, MS (MALDI-FTICR, MALDI-QTOF), antibody immunostaining (CA19-9, TRA-1-60), lectin staining (PHA-E, GSL-II) were used.
To summarize the results, pancreatic duct adenocarcinoma has an increase in the structure of α2-3 Sia, poly-LacNAc, branching, bisecting GlcNAc, core fucose, and terminal GalNAc compared to normal tissues. As for Sia, α2-3Sia is mainly expressed in tumor stroma regions, and α2-6Sia is slightly stronger in adenocarcinoma regions.
IgA nephropathy is a typical intractable disease of chronic kidney disease in which IgA (one of the immunoglobulins) is deposited in the glomerulus (a urine filtration device) with aberrant glycan modification. It is also well known that abnormalities occur in the O-glycan modification in the IgA hinge region.
A group from Central South University, Changsha, China etc. has indicated that IgA, the glycan abnormality found in IgA nephropathy, might be controlled by microRNA (miR-630) derived from tonsil mononucleated cells.
As for the mechanism of the onset of IgA nephropathy, it was suggested that miR-630 derived from the tonsils is produced excessively, and targets Toll-like receptor 4 (TLR4) as the target gene, and finally modulates the concentration of IgA and its glycosylation level through the NF-kB signaling pathway.
A group from Soka University etc. has reported on changes in glycan modification accompanied by change from ESC to epiblast-like cells (EpiLCs) and a control factor behind them.
With the change from ESC to EpiLCs, the following changes in glycan modification occur:
- For N-type glycans, the high mannose structure is the main structure in common, but in EpiLCs, fucose modification, bisecting, and Sia modification are increased, for Sia, α2-6 is the main linkage, and typeI LacNAc (Galβ1-3GlcNAc) is highly expressed with α1-2Fuc modified.
- For O-type sugar chains, Tn antigen and O-GlcNAc are the main in common, but in EpiLCs, the expression of O-glycan is generally increasing, and elongated mucin type O-glycans also increase.
- For Glycosaminoglycans (GAG), EpiLCs generally increase GAG expression, especially Heparan sulfate (HS), chondroitin sulfate (CS) and dermatan sulfate (DS).
- For glycolipids, EpiLCs cause structural changes from globo (Gb) to ganglio (Gg).
Behind these glycan modification, polycomb repressive complex 2 (PRC2), a chromatin protein, was shown to be involved as a regulator. A number of glycosyltransferase genes involved in glycan modification of ESC is under the control of PRC2.
A group of Quilmes National University, Bernal, Buenos Aires Province, Argentina has reported characteristic glycan modification in gliomas.
In high-grade gliomas, its glycan modification is characterized by the progression of terminal sialic acid of N-glycans and multi-antennary N-glycans. The sialic acid modification is mainly α2-3 linkage along with the terminal fucosylation, suggesting that the terminal modification structure of N-glycans is SLex. To support this, glycosyltransferases (α1,3-fucosyltransperases (FuT3-7 and 9-11) and α2,3-sialyltransferases (ST3Gal3/4/6) ) are also highly expressed.
They concluded that changes in the glycan profile of tumor cell surfaces are the basis for the development of therapeutic drugs targeting such aberrant glycans and novel glycan markers.
Toxicology tests using hepatocytes have come to be widely used as an alternative way for testing drug toxicology using animals. The problem with using hepatocytes in toxicology tests is that it is difficult to supply large quantities of hepatocytes with the same characteristics. Therefore, a group from the National Institute of Child Health and Development proposes a method to create hepatocytes from pluripotent stem cells (iPSC, ESC) and enrich highly uniform hepatocellular populations from heterogeneous cell populations using ammonia.
After ESC is differentiated into hepatocytes, an ammonia treatment is performed for 2 days to select uniform hepatocytes that are resistant to ammonia toxicity. 70-80% will die at this stage. Surviving hepatocytes are cultured and proliferated on MEF-feeder. Hepatocytes selected in this way multiply about 30 times in 190 days. The detailed mechanism of ammonia toxicity is not known, but it is thought that ammonia ions compete with potassium ions and eventually die with intracellular and/or extracellular pH change. ALB, AFP, CYP3A4, CPS1, and OTC genes are highly expressed in ammonia-selected hepatocytes, and ALB and AFP decrease with the passage. CPS1 and OTC are genes involved in the metabolism of ammonia. CYP3A4 is one of the enzymes that metabolizes unwanted biological molecules.
The same is possible with hepatocytes made from iPSC.
The differentiated cells from iPSC and /or ECS were further cultivated and propagated in the ESTEM-HE medium (GlycoTechnica, Ltd.) .
Hepatocytes are essential for toxicology testing of pharmaceuticals in vitro. Hepatocyte strains such as HepG2, Huh7, THLE-2, PLC-PRF-5, and AML-12 are used. A group from the National Center for Child Health and Development has established a new immortalized hepatocytes named HepaMN from from a liver associated with biliary atresia. Immortalization was performed by inoculation with CDK4, cyclin D1, and TERT.
Characteristics of HepaMN strains:
Established from untransformed hepatocytes, and has normal liver function and diploid chromosomes,
Expression of albumin gene at the same level as HepaRG,
Showing the cell morphology of hepatocytes,
Induces stable cytochrome P450 3A4 (CYP3A4) and shows normal metabolic effects,
Efficiently proliferates and is stable even in very long passages,
As a result, succeeded in providing a new and useful hepatocyte strain for toxicology testing.
HepaMN can be effectively cultured by EMUKK-15
Existing Pfizer and Modelna vaccines for the new coronavirus (SARS-CoV-2) are mRNA type, but the following group is evaluating prototype vaccines using adeno-associated viral (AAV).
Therapeutic gene transfer using AAV is recognized as a highly safe method, and Glybera, Luxturna, Zortensma etc. have already been approved by the FDA and EMA as gene therapeutics.
Vaccines using two types of AAV have been prototyped. AAVCOVID-19-1 (AC1) encodes a full-length S protein, which expresses an antigen S protein on the cell membrane of an infected cell. Another, AAVCOVID-19-3 (AC3), encodes part of the S protein, and the antigen takes the form of a secretory protein.
The evaluation was carried out with mice and nonhuman primates, and the immune response was retained for about 5 months with a single doze. There is no problem with storage at room temperature for one month, and vaccines are amenable to large scale production because the methodology has been established. As an effect, AC1 seems to be higher than AC3.
However, the blog Admin has some concerns that the antigen genes are incorporated into cells.
It has been pointed out that mutations in the new coronavirus (SARS-CoV-2) are behind infection explosions in the UK and South Africa. A number of mutations have occurred, but a mutation common to these has already been shown to be N501Y.
A group of The University of Texas Medical Branch, Galveston TX has reported on how the mutation affects the effects of Pfizer’s vaccine, Tozinameran (BNT162b2, a nucleoside modified RNA vaccine).
A comparative experiment using N501 and Y501, which is the genetic background of N501, was done by measuring 50% plaque reduction neutralization titers for N501 and Y501 viruses using sera from 20 people collected 2 weeks and 4 weeks after administration of the vaccine. As a result, it was reported that almost the same neutralization titers were obtained.