Evaluation of long-term antibody kinetics in healthcare workers vaccinated with inactivated COVID-19 Vero cell vaccine (CoronaVac), a propensity score-matched observational study

OBJECTIVES

This study aimed to evaluate the long-term antibody kinetics after vaccinating with an inactivated COVID-19 Vero cell vaccine (CoronaVac) in healthcare workers (HCWs) at a single center in Turkey.

METHODS

For this prospective observational study, Chemiluminescence immunoassay (CLIA) and enzyme-linked immunosorbent assay (ELISA) were used for the determination of binding antibodies (bAb) and neutralizing antibodies (nAb), respectively. Antibody kinetics were compared for the potential influencing factors, and propensity score analysis was performed to match the subcohort for age.

RESULTS

Early bAb and nAb response was achieved in all 343 participants. Titers of bAbs against SARS-CoV-2 on 42 days post-vaccination (dpv) were higher in HCWs who were aged <40 years and who had a history of COVID-19. SARS-CoV-2 bAb levels in HCWs on days 42 (n = 97), 90 (n = 97), and 180 (n = 97) were 175 IU/ml (3.9-250), 107 IU/ml (2.4-250), and 66.1 IU/ml (2.57-250), respectively (p<0.001). SARS-CoV-2 bAb (p<0.001) and nAb (p<0.001) titers decreased significantly over time. There was a high negative correlation between SARS-CoV-2 antibody titers and inverse optic density of nAb responses (Pearson correlation coefficient: -0.738, p<0.001).

CONCLUSIONS

When the antibody responses were compared, it was seen that the vaccine immunogenicity was better in those who had prior COVID-19 history and were aged <40 years. In the course of time, it was determined that there was a significant decrease in bAb and nAb responses after the 90th day. These results may guide approval decisions for booster COVID-19 vaccines.

Neoantigens derived from differential mutations of invasive ductal carcinomas with axillary lymph node metastasis

Invasive ductal carcinomas (IDCs) are the most common breast cancer type. It was reported that almost 80% of breast cancers are IDCs. IDCs can be treated by immunotherapy using neoantigens. Therefore, common neoantigens that are specific for ductal carcinomas should be determined. We aimed to determine differential expression of neoantigens for IDCs in the presence or absence of axillary lymph node metastasis. DNA was isolated from paraffin-embedded (FFPE) tissue specimens by using GeneRead DNA FFPE Kit. QIAseq Targeted DNA panel for human breast cancer was used for sequencing of isolated tumor DNA. Next generation sequencing was performed using a Illumina MiSeq. Total exons of 93 genes were studied. A bioinformatic analysis was conducted by a platform-specific pipeline software (Qiagen Clinical Insight-AnalyseTM and Clinical Insight-InterpretTM). We found significant variations in several genes for individuals with or without axillary lymph node metastasis. In particular, variations in CDKN2A and PIK3R1genes were quite interesting to determine individual neoantigens of ductal carcinomas as potential immunotherapy targets. Currently, these findings are still under further investigations. Based on these findings, we concluded that NGS analysis is a very powerful technology in determination of specific neoantigens of individuals with ductal carcinomas. Also NGS can be used to discover new genes related to axillary lymph node metastasis for ductal carcinomas. Supported by Gazi University BAP.

Aluminum hydroxide and calcium phosphate adjuvants in adsorbed tetanus and diphtheria vaccines: Immunologic vs histopathologic effects

We aimed to study effects of aluminum hydroxide (AH) and calcium phosphate (CAP) adjuvants in potentiation of new tetanus and diphtheria vaccines that have been developed in our laboratory. AH gel or CAP nanoparticles were prepared in vaccine formulations in adsorbed tetanus or tetanus-diphtheria (Td) vaccines. Vaccine formulations were injected to 8-week old female Balb/c mice. Only phosphate buffered saline (PBS) was injected to control animals. Tissue samples, peripheral blood samples and spleen cells were collected from each mouse. Serum was separated by centrifugation of peripheral blood. Spleen cells were stained with anti-CD4-FITC, anti-CD8-PE, and anti-CD19-APC monoclonal antibodies. ELISA was performed to test presence of anti-tetanus or anti-diphtheria antibodies. We found that either a single dose or an additional booster doses did not change significantly the composition of lymphocyte distribution in AH and CAP adjuvant injected mice in comparison to the control animals. No significant difference was detected for CD4/CD8 ratio and for CD19-expressing cell number. However, presence of IgM and IgG antibodies that were specific for both tetanus and diphtheria toxins increased significantly following injection of vaccines. Granulomas and cyst formation after subcutaneous injections of CAP-containing vaccines at the site of injection were evaluated. Supported by Gazi University BAP, No: 64/2018-04.

Sevoflurane exerts brain-protective effects against sepsis-associated encephalopathy and memory impairment through caspase 3/9 and Bax/Bcl signaling pathway in a rat model of sepsis

Objective We compared the effects of sevoflurane and isoflurane on systemic inflammation, sepsis-associated encephalopathy, and memory impairment in a rat sepsis model of cecal ligation and puncture (CLP)-induced polymicrobial peritonitis. Methods Twenty-four rats were assigned to sham, CLP, CLP + sevoflurane, and CLP + isoflurane groups. At 72 hours after CLP, the rats underwent behavior tests. Serum cytokines were evaluated. Brain tissue samples were collected for determination of glutathione peroxidase (GPX), superoxide dismutase (SOD), and catalase; the wet/dry weight ratio; myeloperoxidase (MPO) and malondialdehyde (MDA); apoptotic gene release; and histologic examinations. Results The MPO level, wet/dry weight ratio, and histopathology scores were lower and the Bcl2a1 and Bcl2l2 expressions were upregulated in both the CLP + sevoflurane and CLP + isoflurane groups compared with the CLP group. The interleukin-6, interleukin-1β, MDA, and caspase 3, 8, and 9 levels were lower; the GPX, SOD, Bax, Bcl2, and Bclx levels were higher; and non-associative and aversive memory were improved in the CLP + sevoflurane group compared with the CLP + isoflurane group. Conclusion Sevoflurane decreased apoptosis and oxidative injury and improved memory in this experimental rat model of CLP. Sevoflurane sedation may protect against brain injury and memory impairment in septic patients.

A shift in the balance of regulatory T and T helper 17 cells in rheumatic heart disease

BACKGROUND

Autoimmunity plays an essential role in the pathogenesis of rheumatic heart disease (RHD); however, cellular mechanisms of autoimmune response are unclear. Whereas T helper 17 (TH17) and regulatory T cells (Treg) cells share a common differentiation pathway, they play opposite roles in the immune tolerance and autoimmune diseases. Although high TH17/Treg ratio has been shown in several autoimmune diseases, no data are available in RHD. This study investigated the balance between TH17 and Treg in rheumatic mitral valve disease (MVD).

METHODS

Forty patients with rheumatic MVD and 23 control subjects were enrolled into the study. All subjects underwent clinical, electrocardiographic, and echocardiographic evaluation. The percentages of circulating TH17 and Treg cells were analyzed by flow cytometry. Serum levels of high-sensitivity C-reactive protein (hs-CRP) and cytokines were assessed by enzyme-linked immunosorbent assay.

RESULTS

As compared with control subjects, rheumatic MVD patients showed significant increase in peripheral TH17 percentage, high serum levels of TH17-related cytokine interleukin 17A, and an obvious decrease in the percentage of Treg cells. T helper 17/Treg ratio was significantly high in rheumatic MVD patients compared with control subjects (P = 0.0001). Serum concentrations of hs-CRP in rheumatic MVD group were higher than those of the control subjects, and hs-CRP levels correlated with the TH17/Treg ratio (r = 0.71, P = 0.0001). Serum levels of transforming growth factor β1 were increased in rheumatic MVD group compared with those of the control subjects.

CONCLUSIONS

The results indicated that high TH17/Treg ratio exists inrheumatic MVD. This imbalance may play a role in the pathogenesis, and TH17/Treg balance may be a promising therapeutic approach in RHD.

Establishment of a primary pleomorphic xanthoastrocytoma cell line: in vitro responsiveness to some chemotherapeutics

BACKGROUND

Anaplastic pleomorphic xanthoastrocytoma is an aggressively growing, malignant, and eventually fatal tumor of the central nervous system. Testing chemotherapeutic drug sensitivity under in vitro conditions would be a useful strategy to determine sensitive or resistant drugs for fatal brain cancers.

OBJECTIVE

To establish primary cell cultures of excised tumor tissue from pleomorphic xanthoastrocytoma-bearing patients and to test their sensitivity against various anticancer chemotherapy drugs.

METHODS

Prepared suspensions of the excised tumor tissue from a patient who had a recurrent grade 3 pleomorphic xanthoastrocytoma was cultured in culture dishes until cells began to grow. Immunofluorescent and immunohistochemical visualizations were performed using confocal and light microscopy. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay in comparison with ³H-thymidine incorporation assay was used to test cellular toxicity of several anticancer drugs.

RESULTS

We established vigorously growing primary cells of the tumor. Drug sensitivity testing was conducted successfully.

CONCLUSION

Primary cell cultures of surgically removed tumor tissues may be useful in studies of cancer biology and chemotherapeutic drug sensitivity for recurrent malignant brain tumors, particularly for anaplastic pleomorphic xanthoastrocytoma.

TSH-induced gene expression involves regulation of self-renewal and differentiation-related genes in human bone marrow-derived mesenchymal stem cells

Bone marrow-derived mesenchymal stem cells are pluripotent cells that are capable of differentiating into a variety of cell types including neuronal cells, osteoblasts, chondrocytes, myocytes, and adipocytes. Despite recent advances in stem cell biology, neuroendocrine relations, particularly TSH interactions remain elusive. In this study, we investigated expression and biological consequence of TSH receptor (TSHR) interactions in mesenchymal stem cells of cultured human bone marrow. To the best of our knowledge, we demonstrated for the first time that human bone marrow-derived mesenchymal stem cells expressed a functional thyrotropin receptor that was capable of transducing signals through cAMP. We extended this study to explore possible pathways that could be associated directly or indirectly with the TSHR function in mesenchymal stem cells. Expression of 80 genes was studied by real-time PCR array profiles. Our investigation indicated involvements of interactions between TSH and its receptor in novel regulatory pathways, which could be the important mediators of self-renewal, maintenance, development, and differentiation in bone marrow-derived mesenchymal stem cells. TSH enhanced differentiation to the chondrogenic cell lineage; however, further work is required to determine whether osteoblastic differentiation is also promoted. Our results presented in this study have opened an era of regulatory events associated with novel neuroendocrine interactions of hypothalamic-pituitary axis in mesenchymal stem cell biology and differentiation.

Differential immunomodulatory activity of soluble beta glucans from barley and yeast in antigen specific humoral immune responses (45.21)

The main difference in chemical structure of (1 →3)-β-D-glucans from yeast cell wall and barley is the branching side chains. Yeast cell wall contains (1→3),(1→6)-β-D-glucans whereas barley contains (1→3),(1→4)-β-D-glucans. The purpose of this study was to compare adjuvant effects of two soluble beta-glucans from barley and yeast (Saccharomyces cerevisiae) in antigen specific humoral immune responses. In a conalbumin-immunized mouse model, mice were immunized by conalbumin at a relatively lower concentration (10 μg/mouse) in the presence of beta glucans. Anti-conalbumin antibodies in the serum specimens of immunized and control mice were quantified by ELISA.

At high doses, both glucans were effective in increasing circulating conalbumin-specific antibodies of IgM, IgG, and IgA types. However, 1 μg of â-glucan from barley resulted in lower yield in IgG1, IgG2a, IgG2b, and IgGA levels in comparison to the yeast-derived glucan at the same dose. We also found that antigen specific antibody levels enhanced by the β-glucan from yeast were always higher than those of the glucan from barley.

In conclusion, yeast-derived glucans might have better immunomodulatory or adjuvat activity in induction of antigen specific humoral immune responses over barley-derived glucans.β

Rapid and transient reduction in circulating thyroid hormones following systemic antigen priming: implications for functional collaboration between dendritic cells and thyroid

The thyroid hormones T(3) (tri-iodothyronine) and T(4) (thyroxine) are disseminated throughout the body via the circulation and are maintained across a range of physiological concentrations under the control of thyroid-stimulating hormone (TSH). T(3) (and T(4) after conversion to T(3)) influences many biological activities, including gene expression and protein synthesis, though little is known about the nature of pituitary-thyroid immune interactions. In the present study we show that serum T(3) and T(4) levels are sharply but transiently reduced during the first 24 h of systemic antigen exposure and that this is followed by suppressed levels of free T(4), after which there is rapid recovery to normal levels. Splenic dendritic cells, depending upon the stage of maturation/activation, were found to be a rich source of TSH, and CD11c(+) cells with dendritic cell morphology were present in the thyroid 1-3 days after antigen exposure. Moreover, antigen priming of hypophysectomized mice that are unable to make pituitary-derived TSH resulted in significant increases in circulating T(4), implying that compensation in the drop in thyroid hormones can be regulated from extrapituitary sources. These findings thus identify a novel set of immune-endocrine interactions that transpire during the early phase of antigen exposure, and they suggest that under appropriate conditions the immune system directly participates in the process of maintaining physiological homeostasis by contributing to the regulatory control of thyroid hormone activity.

CD43 potentiates CD3-induced proliferation of murine intestinal intraepithelial lymphocytes

The involvement of CD43 in cell proliferation of murine intestinal intraepithelial lymphocytes (IEL) has been studied in in vitro CD3-stimulated cell cultures. In the presence of either IL-2 or IL-15, CD3 stimulation of IEL resulted in low levels of proliferation as measured by thymidine incorporation, whereas no proliferation occurred upon CD3 stimulation in the absence of cytokines. The combination of both cytokines to IEL cultures synergistically enhanced CD3-induced proliferation by approximately threefold that of cultures supplemented with either cytokine alone. Most importantly, however, proliferation of IEL was significantly greater when CD3 stimulation occurred in conjunction with CD43 triggering, indicating that CD43 functions as a coactivational signal for murine IEL. These findings indicate that a spectrum of potential proliferative responses exist among murine IEL depending on the types and combinations of signals received, and that because under normal conditions murine IEL are largely devoid of CD28 expression, a classical T-cell coactivational molecule, the capacity for high-level IEL proliferation may reside with CD43.

Origins of intestinal intraepithelial lymphocytes: direct evidence for a thymus-derived gamma delta T cell component

The contribution of T cell precursors from the thymus and the bone marrow to the pool of intestinal intraepithelial lymphocvtes (IELs) has been studied in a system using donor cells from enhanced-green fluorescent protein (EGFP+ ) transgenic mice a doptively transferred into EGFP- recipient mice. Consistent with previous studies, regeneration of gamma delta and alpha beta T cell populations in the intestinal epithelium occurred within 2-3 weeks of bone marrow transfer into irradiatiated EGFP- animals and prior to T cell repopulation of the spleen, of interest, however, although transfer of whole adult EGFP+ thymocytes to non-irradiated EGFP- congenitally-athymic nude mice produced alpha beta T cells in both the spleen and intestine. Gamma delta T cells in significant number were detected only in the intestine of recipient mice. In contrast, transfer of CD3-, CD4-, CD8- immature thymocytes resulted in no detectable T cells in either the intestine or the spleen of nude mice up to twelve weeks post-cell transfer, suggesting that intestinal IELs generated from thymocytes arose from differentiated lineage-committed cells rather than from immature thymocytes. These findings provide direct evidence for both thymus-independent and thymus-dependent sources of intestinal gamma delta T cells, and they suggest that murine IELs consist of diverse groups of T cells with distinct developmental origins.

Neuroendocrine-induced synthesis of bone marrow-derived cytokines with inflammatory immunomodulating properties

Although cytokines and other soluble regulators of immunity are known to be involved in hematopoiesis, little is known about the signals that induce the synthesis of those mediators locally. Based on recent studies linking the neuroendocrine hormone thyrotropin [thyroid-stimulating hormone (TSH)] to immune cell function in other tissues, we investigated the capacity of TSH to activate cytokine responses from bone marrow cells. These studies reveal that stimulation of the TSH receptor on bone marrow cells-using highly purified or recombinant TSH or by direct stimulation with anti-TSH receptor antibodies-rapidly induces the synthesis of cytokines from bone marrow cells that are classically used in the regulation of inflammatory responses. Of 13 cytokines screened for activity by ELISA or by RNase protection assays for gene expression, IL-6, IFN-beta, TNFalpha, TNFbeta, TGFbeta2, and lymphotoxin-beta responses were reproducibly induced by TSH within 2-3 h of stimulation. Intracellularly, TSH stimulation of bone marrow cells caused rapid increases in cAMP levels and induced the phosphorylation of the Jak2 protein kinase, thereby defining a novel G-protein-coupled receptor/cytokine synthesis pathway. These findings demonstrate that TSH can serve as a primary inductive signal of cytokine production by bone marrow cells.