Immune profiling of SARS-CoV-2 infection during pregnancy reveals NK cell and γδ T cell perturbations

Pregnancy poses a greater risk for severe COVID-19; however, underlying immunological changes associated with SARS-CoV-2 during pregnancy are poorly understood. We defined immune responses to SARS-CoV-2 in unvaccinated pregnant and nonpregnant women with acute and convalescent COVID-19, quantifying 217 immunological parameters. Humoral responses to SARS-CoV-2 were similar in pregnant and nonpregnant women, although our systems serology approach revealed distinct antibody and FcγR profiles between pregnant and nonpregnant women. Cellular analyses demonstrated marked differences in NK cell and unconventional T cell activation dynamics in pregnant women. Healthy pregnant women displayed preactivated NK cells and γδ T cells when compared with healthy nonpregnant women, which remained unchanged during acute and convalescent COVID-19. Conversely, nonpregnant women had prototypical activation of NK and γδ T cells. Activation of CD4+ and CD8+ T cells and T follicular helper cells was similar in SARS-CoV-2-infected pregnant and nonpregnant women, while antibody-secreting B cells were increased in pregnant women during acute COVID-19. Elevated levels of IL-8, IL-10, and IL-18 were found in pregnant women in their healthy state, and these cytokine levels remained elevated during acute and convalescent COVID-19. Collectively, we demonstrate perturbations in NK cell and γδ T cell activation in unvaccinated pregnant women with COVID-19, which may impact disease progression and severity during pregnancy.

Impact of SARS-CoV-2 transmission-based precautions on inpatient management of general medical patients

This audit reviewed the impact on access to routine medical care and adverse outcomes in patients with suspected SARS‐CoV‐2 infection managed on a ‘COVID‐19’ (CV) ward compared with a general medicine ward at Box Hill Hospital, Victoria. Data were collected at two time points to capture changes associated with onsite testing. We found no healthcare delays from admission to CV wards and observed faster exits from CV wards with improved testing efficiency. This critical finding is relevant as Victoria manages a third wave of infections.

SARS-CoV-2 seroprevalence in healthcare workers in a tertiary healthcare network in Victoria, Australia

BACKGROUND

Healthcare workers (HCW) are exposed to an increased risk of COVID-19 through direct contact with patients and patient environments. We calculated the; seroprevalence of SARS-CoV-2 in HCW at Eastern Health, a tertiary healthcare network in Victoria, and assessed associations with demographics, work location and role.

METHODS

A cross-sectional cohort study of HCW at Eastern Health was conducted. Serum was analysed for the presence of antibodies to SARS-CoV-2, and all participants completed; an online survey collecting information on demographics, place of work, role, and exposures; to COVID-19. Seroprevalence was calculated as the proportion participants with SARS-CoV-2; antibodies out of all tested individuals.

RESULTS

The crude seroprevalence of SARS-CoV-2 antibodies in this study was 2.17% (16/736). Thirteen of the 16 (81.2%) positive cases had previously been diagnosed with COVID-19 by PCR: the seroprevalence in the group not previously diagnosed with COVID by PCR was 0.42% (3/720). Having direct contact with COVID-19 patients did not increase the likelihood of having positive serology. A prior history of symptoms consistent with COVID-19 was associated with a higher likelihood of having positive serology (OR 17.2, p = 0.006, 95%CI: 2.25-131.55).

CONCLUSION

Our calculated seroprevalence of 2.17% is higher than estimated in the general Australian population, but lower than that reported in HCW internationally. The; majority of those with positive serology in our study had previously been diagnosed with COVID-19 by PCR based testing. Seropositivity was not associated with interaction with COVID-19 positive patients, highlighting effective infection prevention and control practices within the workplace.

Dimeric IgA is a specific biomarker of recent SARS-CoV-2 infection

Current tests for SARS-CoV-2 antibodies (IgG, IgM, IgA) cannot differentiate recent and past infections. We describe a point of care, lateral flow assay for SARS-CoV-2 dIgA based on the highly selective binding of dIgA to a chimeric form of secretory component (CSC), that distinguishes dIgA from monomeric IgA. Detection of specific dIgA uses a complex of biotinylated SARS-CoV-2 receptor binding domain and streptavidin-colloidal gold. SARS-CoV-2-specific dIgA was measured both in 112 cross-sectional samples and a longitudinal panel of 362 plasma samples from 45 patients with PCR-confirmed SARS-CoV-2 infection, and 193 discrete pre-COVID-19 or PCR-negative patient samples. The assay demonstrated 100% sensitivity from 11 days post-symptom onset, and a specificity of 98.2%. With an estimated half-life of 6.3 days, dIgA provides a unique biomarker for the detection of recent SARS-CoV-2 infections with potential to enhance diagnosis and management of COVID-19 at point-of-care.

Is the current usage of dental general anaesthetic appropriate?

Ten years on: Is dental general anaesthesia in childhood a risk factor for caries and anxiety?

Cloning and characterization of chicken growth hormone binding protein (cGHBP)

Growth hormone (GH) is indispensable for the growth of animals and its biological activity is mediated by binding to the growth hormone receptor (GHR) [Harvey S, Scanes CG, Daughaday WH. Growth hormone. Boca Raton: CRC Press; 1995]. GHR is a transmembrane protein responsible for signal transduction upon GH binding. GH also binds to the growth hormone binding protein (GHBP) which is the soluble form of GHR extracellular domain existing in circulation. Actions of GHBP include prolongation of GH bioavailability and prevention of GH signaling system from over-stimulation. To date, little is known about the mechanisms generating the chicken GHBP (cGHBP). Elucidating the genomic structure of cGHR will provide insights into such underlying mechanisms. Using polymerase chain reaction and library screening methods, we have characterized the genomic organization of chicken GHR (cGHR). The full-length coding region of the cGHR transcript is composed of eight exons (exons 2-10), lacking a human homolog exon 3 and spans at least 71 kb on the genome. A novel transcript of size 1.2kb was isolated from chicken liver total RNA using 5' and 3' rapid cDNA ends amplification (RACE). It was generated by utilizing a previously unknown polyadenylation signal located at the intron 6. Semi-quantitative reverse transcription polymerase chain reaction showed that this transcript is widely expressed in a variety of tissues. This transcript has an open reading frame comprising 203 amino acids. In vitro binding assay using ELISA demonstrated that Escherichia coli expressed recombinant protein encoded by this transcript was able to bind with chicken GH. Hence, this transcript is a potential candidate for cGHBP.

Frequent DAP kinase but not p14 or Apaf-1 hypermethylation in B-cell chronic lymphocytic leukemia

Dysregulation of apoptosis, and thus the p14/DAP kinase/HDM2/p53/Apaf-1 pathway, is potentially important in carcinogenesis. Chronic lymphocytic leukemia (CLL), uncommon in the Chinese, is a disease characterized by impaired apoptosis, of the neoplastic lymphocytes. Hypermethylation of p14, DAP kinase and Apaf-1 was studied by methylation-specific polymerase chain reaction (MSP) with primers for methylated (M-MSP) and unmethylated (U-MSP) alleles in 50 diagnostic marrow samples from patients with CLL. Chinese CLL patients had an indolent course similar to Caucasians with median overall survival (OS) of 96 months, which was adversely affected by advanced Rai stage (projected 5-year OS = 72% and 39% for Rai < or = 2 and Rai > 2; P = 0.01). DAP kinase was methylated in 18 (36%) patients while p14 and Apaf-1 were completely unmethylated in all the primary CLL samples. There was no correlation between DAP kinase hypermethylation and age, sex, poor-risk karyotype, lymphocyte count and Rai stage at diagnosis. Projected OS for patients with and without DAP kinase hypermethylation were 59 and 57% (P = 0.91). DAP kinase, but not p14 and Apaf-1, of the DAP kinase/p14/HDM2/p53/Apaf-1 pathway is frequently hypermethylated in CLL, but not of prognostic significance. Moreover Chinese patients with CLL share a similarly indolent clinical course, and this is the first comprehensive study on p14, DAP kinase and Apaf-1 hypermethylation in CLL.

Methylation of INK4 and CIP/KIP families of cyclin-dependent kinase inhibitor in chronic lymphocytic leukaemia in Chinese patients

BACKGROUND

INK4 (p15, p16, p18 and p19) and CIP/KIP (p21, p27 and p57) are two families of cyclin-dependent kinase inhibitors (CKI) targeting CDK4/6 and CDK2, respectively.

AIM

To study the role of methylation in the inactivation of CKI in chronic lymphocytic leukaemia (CLL).

MATERIALS AND METHODS

Methylation-specific polymerase chain reaction was carried out on DNA obtained from the bone marrow of 56 newly diagnosed patients with CLL.

RESULTS

Similar demographic features and clinical outcome were observed in our patients when compared with Caucasian patients, including an indolent clinical course (10-year overall survival 51%) and advanced Rai stage (p = 0.006), and a high-risk karyotype such as trisomy 12 and complex aberrations (p = 0.03). In the INK4 family, methylation in p15 and p16 occurred in 20 (35.7%) and 8 (14.3%) patients, respectively. In all, 5 (8.9%) CLL samples harboured concurrent methylation of both p15 and p16. Apart from an association of p16 methylation with higher presenting leucocyte count (64.5 x 10(9)/l in methylated p16 and 16.0 x 10(9)/l in unmethylated p16 patients; p = 0.016), there was no association between p15 and p16 methylation and age, sex and Rai stage. No difference was observed in the overall survival for patients with and without p15 and p16 methylation. By contrast, p18 and Rb were unmethylated in all samples. In the CIP/KIP family, apart from infrequent methylation of p57 in 4 (7.1%) patients, methylation of p21 and p27 was uniformly absent.

CONCLUSION

p15 and, less frequently, p16 of the INK4 family of CKI, instead of the CIP or KIP family, were targeted by methylation in CLL. p16 methylation was associated with a higher lymphocyte count at presentation. This is the first comprehensive study of the epigenetic dysregulation of the INK4 and CIP/KIP families of CKI in Chinese patients with CLL.

Infrequent Wnt inhibitory factor-1 (Wif-1) methylation in chronic lymphocytic leukemia

The Wnt pathway has been shown recently, to be activated in patients with chronic lymphocytic leukemia (CLL). This is the first study to examine the role of Wnt inhibitory factor-1 (Wif-1) methylation in the pathogenesis of haematolymphoid malignancies. Wif-1, a putative tumor suppressor, is a soluble negative regulator of the Wnt pathway activated in CLL. We studied the role of methylation of Wif-1 in 43 Chinese patients with CLL. At diagnosis, Wif-1 methylation was detected in 5/43 (11.6%) CLL marrow samples. Wif-1 methylation occurred more frequently in patients with advanced age (p = 0.059) but there was no correlation between Wif-1 methylation and sex, lymphocyte count and Rai stage at diagnosis. In conclusion, Wif-1 is infrequently methylated in CLL. Other factors leading to activation of the Wnt pathway warrant further study.

Aberrant promoter methylation of the retinoic acid receptor alpha gene in acute promyelocytic leukemia

The retinoic acid receptor alpha (RARA) gene is disrupted by PML/RARA fusion in acute promyelocytic leukemia (APL). The P2 promoter of RARA, controlling the RARalpha2 isoform, contains an RA-responsive element and may be targeted in APL. To test whether aberrant methylation of P2 was involved, 47 APL at diagnosis, 16 APL at first relapse, 50 acute myeloid leukemia (AML) and 22 acute lymphoblastic leukemia (ALL) were tested by methylation-specific polymerase chain reaction. RARA P2 methylation was highly associated with APL (APL: 25/63 vs AML/ALL: 2/75, P<0.0001). P2 methylation occurred at similar frequencies in APL at diagnosis and relapse, suggesting it was an initiating leukemogenic event. In the APL line NB4, RARalpha2 was not expressed, with the untranslocated RARA shown to be P2 methylated. 5-Azacytadine treatment of NB4 led to progressive P2 demethylation and re-expression of RARalpha2, confirming that RARA methylation collaborated with PML/RARA in totally suppressing RARalpha. In APL, RARA P2 methylation was unrelated to gender, age, presenting leukocyte counts and additional cytogenetic aberrations. For APL patients receiving all-trans retinoic acid for induction, P2 methylation did not affect the complete remission rates and survivals. RARA is the first myeloid-specific transcription factor shown to be dysregulated by both translocation and aberrant methylation.

B7-H3: a costimulatory molecule for T cell activation and IFN-gamma production

We describe here a newly identified member of the human B7 family, designated B7 homolog 3 (B7-H3), that shares 20-27% amino acid identity with other B7 family members. B7-H3 mRNA is not detectable in peripheral blood mononuclear cells, although it is found in various normal tissues and in several tumor cell lines. Expression of B7-H3 protein, however, can be induced on dendritic cells (DCs) and monocytes by inflammatory cytokines and a combination of phorbol myristate acetate (PMA) + ionomycin. Soluble B7-H3 protein binds a putative counter-receptor on activated T cells that is distinct from CD28, cytotoxic T lymphocyte antigen 4 (CTLA-4), inducible costimulator (ICOS) and PD-1. B7-H3 costimulates proliferation of both CD4+ and CD8+ T cells, enhances the induction of cytotoxic T cells and selectively stimulates interferon gamma (IFN-gamma) production in the presence of T cell receptor signaling. In contrast, inclusion of antisense B7-H3 oligonucleotides decreases the expression of B7-H3 on DCs and inhibits IFN-gamma production by DC-stimulated allogeneic T cells.Thus, we describe a newly identified costimulatory pathway that may participate in the regulation of cell-mediated immune responses.

Heterogeneous nuclear ribonucleoproteins as regulators of gene expression through interactions with the human thymidine kinase promoter

In search for nuclear proteins that interact with the human thymidine kinase (htk) promoter, we discovered that p37AUF, a hnRNP C-like protein, and hnRNP A1, both members of the heterogeneous ribonucleoprotein family, can bind with high affinity to an ATTT sequence motif contained within the cell cycle regulatory unit (CCRU). We report here that over-expression of p37AUF stimulates gene expression mediated by the htk promoter in a promoter-sequence specific manner, whereas hnRNP A1 suppresses it. Both recombinant p37AUF and hnRNP A1 can bind the htk CCRU, suggesting that their binding to the DNA target does not require additional cellular components. We further discovered that hnRNP K is a potent suppressor of htk mediated gene activity. However, its mechanism of action is mediated through protein-protein interaction, since hnRNP K itself cannot bind the htk CCRU but can competitively inhibit the binding of other hnRNPs. The binding site for the hnRNPs on the htk CCRU is not required for S-phase induction of the htk promoter. However, in stable but not transient transfectants, the mutation of the hnRNP binding site results in 5- to 10-fold reduction of htk mediated gene activity in synchronized and exponentially growing cells. Collectively, these findings support emerging evidence that hnRNPs, in addition to their traditional role in RNA biogenesis, could be regulators of gene expression through direct DNA binding or interaction with other proteins.

Autologous bone marrow transplantation for patients with acute myeloid leukaemia: prospective follow-up study

OBJECTIVE

To study the use of autologous bone marrow transplantation to treat acute myeloid leukaemia when complete remission had been achieved and when no human leukocyte antigen matched related donor was available.

DESIGN

Prospective follow-up study.

SETTING

Government hospital, Hong Kong.

PATIENTS

Eight patients (median age, 34 years [range, 16-45 years]) with acute myeloid leukaemia in whom complete remission had been achieved.

INTERVENTION

Conditioning regimen of carmustine, amsacrine, etoposide VP-16, cytarabine, and infusion of unpurged marrow.

MAIN OUTCOME MEASURES

Median time taken to reach neutrophil and platelet counts of > or =0.5 x 10(9) /L and > or = x 10(9) /L, respectively; mortality and relapse rates; and follow-up regimens used.

RESULTS

Engraftment was successfully achieved in all patients and there were no early procedure-related mortalities. The median times required to reach a neutrophil count of > or =0.5 x 10(9) /L and a platelet count of > or =20 x 10(9) /L were 30 days (range, 18-36 days) and 38 days (range, 15-53 days), respectively. The median duration of hospital stay was 37 days (range, 25-43 days). Two patients died of a relapse of leukaemia at 6 and 9 months post-transplantation. Two patients experienced relapses: one at 8 months post-transplantation, for which conventional chemotherapy was restarted, and one at 18 months; treatment with all-trans-retinoic acid and conventional chemotherapy achieved a third complete remission in the latter patient, who had acute promyelocytic leukaemia. Continuous remission has been achieved in four of the eight patients after a median follow-up duration of 26 months (range, 6-43 months).

CONCLUSION

Autologous bone marrow transplantation is an acceptable treatment for patients with acute myeloid leukaemia who lack a human leukocyte antigen-matched related donor.

Positive and negative regulation of the human thymidine kinase promoter mediated by CCAAT binding transcription factors NF-Y/CBF, dbpA, and CDP/cut

The proximal CCAAT element located 38 bp upstream of the transcription initiation site contributes to the human thymidine kinase (htk) promoter activity, because site-directed mutagenesis of a 10-bp region containing this CCAAT motif (TKC1) reduced the promoter activity by 55%. Through binding site competitions and antigenic cross-reactivity, the major factor that binds TKC1 from both HeLa and hamster nuclear extracts is identified as NF-Y/CBF. In serum-stimulated cells, the binding of NF-Y/CBF to TKC1 increased gradually, reaching a plateau at the S phase. In cell transfection assays, a dominant-negative mutant of NF-Y/CBF inhibited the htk promoter in a dosage-dependent manner, providing direct evidence that NF-Y/CBF is required for maximal htk promoter activity. Recently, it has been demonstrated that the site occupied by NF-Y/CBF also binds the serum-inducible dbpA and dpbB. We show here that recombinant dbpA interacts with the htk promoter, and overexpression of dbpA can stimulate htk promoter activity mediated through TCK1. In contrast, CDP/cut, the CCAAT displacement protein with known repressor property, binds the htk promoter through both the proximal and distal CCAAT elements. Our discovery that CDP/cut binds the htk promoter primarily in quiescent cells and that overexpression of CDP/cut inhibits htk promoter activity provides an explanation for the reported dramatic increase in htk promoter activity in serum-starved cells when both CCAAT elements were mutated. Thus, a combination of suppression in quiescent cells and activation in serum-stimulated cells mediated through various CCAAT-binding proteins may account in part for the induction of htk promoter activity as quiescent cells reenter the cell cycle.