A224 COVID-19 INFECTION IN LIVER TRANSPLANT RECIPIENTS: CLINICAL FEATURES, HOSPITALIZATION, AND MORTALITY FROM A CANADIAN MULTICENTRE COHORT

Background

The COVID-19 pandemic has brought significant challenges to clinicians caring for liver transplant (LT) recipients. Researchers have sought to better understand the risk and clinical outcomes of LT recipients infected with COVID-19 globally, however, there is a paucity of data from within Canada.

Aims

Our multi-center study aims to examine the characteristics and clinical outcomes of LT patients with COVID-19 in Canada.

Methods

We identified a retrospective cohort of adult LT recipients with RT-PCR confirmed COVID-19 from 7 Canadian tertiary care centers between March 2020 and June 2021. Demographic and clinical data were compiled by clinicians within those centers. We identified liver enzyme profile at the time of COVID-19 infection, immunosuppression type and post-infection adjustments, rate of hospitalization, ICU admission, mechanical ventilation, and death.

Results

A total of 49 patients with a history of LT and COVID-19 infection were identified. Twenty nine patients (59%) were male, the median time from LT was 66 months (1, 128) and the median age at COVID-19 infection was 59 years (52, 65). At COVID-19 diagnosis, the median ALT was 37 U/L (21, 41), AST U/L was 34 (20, 37), ALP U/L was 156 (88, 156), Total Bilirubin was 11 umol/L (7, 14), and INR was 1.1 (1.0, 1.1). The majority of patients (92%) were on tacrolimus monotherapy or a combination of tacrolimus and mycophenolate mofetil (MMF); median tacrolimus level at COVID-19 diagnosis was 5.3 ug/L (4.0, 8.1). Immunosuppression was modified in 8 (16%) patients post-infection; either the tacrolimus dose was reduced or MMF was held. One patient developed acute cellular rejection which recovered after re-initiation of the prior regimen. Eighteen patients (37%) required hospitalization, 6 (12%) were treated with dexamethasone, and 3 (6%) required ICU admission and mechanical ventilation. Four patients (8%) died due to complications of COVID-19. On univariate analysis, neither age, sex, co-morbidities nor duration post-transplant were associated with risk of hospitalization.

Conclusions

In our national retrospective study, approximately 40% of patients required hospitalization with a mortality rate of < 10%. Previous studies have shown proximity to LT as an independent factor for mortality with COVID-19; the median time from LT for our patients was 5 years, which may explain the lower mortality rate. Of note, the median tacrolimus levels were much lower in comparison to the target of 8–10 ug/L used in the first year post-transplant. As the landscape of COVID-19 changes with vaccination, evolving treatments, and increasing rates of variant transmission, additional studies are required to continue identifying trends in clinical outcomes.

Funding Agencies

None

Transgenic double-stranded RNA rice, a potential strategy for controlling striped stem borer (Chilo suppressalis)

BACKGROUND

Although the striped stem borer (SSB, Chilo suppressalis Walker) is a devastating pest of rice that causes significant economic losses, management options are currently limited. Plant-mediated RNA interference (RNAi) is an emerging crop protection technique in which transgenic plants are modified to express insect-specific double-stranded RNAs (dsRNAs) that trigger RNAi silencing in target pests.

RESULT

In this study, an RNAi-based screen of 35 candidate SSB genes identified a small heat shock protein gene (CssHsp) as a potential plant-based RNAi target. To assess its utility in planta, a total of 39 transgenic rice plants were generated, with 11 independent transformants found to contain a single copy of the dsCssHsp expression cassette. In life-time feeding bioassays, three transgenic lines (DS10, DS35, DS36) were found to have significant negative impacts on SSB populations. After feeding for 8 days, mortality in the three transgenic lines exceeded 60%. By pupation, mortality further increased to 90% and few SSB survived to eclosion. Gene expression analyses confirmed that CssHsp transcript levels were significantly reduced after feeding on the transgenic dsCssHsp rice.

CONCLUSION

These results demonstrate the potential for developing a plant-mediated RNAi strategy targeting CssHsp as a more biorational field-based approach for SSB control. © 2021 Society of Chemical Industry.

Lipid Anchoring Improves Lubrication and Wear Resistance of the Collagen I Matrix

Osteoarthritis is a prevalent degenerative joint disease characterized by progressive articular cartilage loss and destruction. The resultant increase in friction causes severe pain. The collagen I matrix (COL I) has been used clinically for cartilage repair; however, how COL I acts at cartilage surfaces is unclear. Here, we studied adsorption and lubrication of synovial fluid components, albumin, γ-globulin, and the phospholipid DPPC, on COL I under physiological conditions using surface plasmon resonance and an in situ sensing surface force apparatus. Our results revealed COL I had poor lubrication ability, a fairly high coefficient of friction (COF, μ = 0.651 ± 0.013), and surface damage under a 7 mN load. DPPC formed an improved lubricating layer on COL I (μ = 0.072 ± 0.016). In sharp contrast, albumin and γ-globulin exhibited poor lubrication with an order of magnitude higher COF but still provided benefits by protecting COL I from wear. Hence, DPPC on COL I may help optimize COL I implantation design.

Advances in nanocellulose-based materials as adsorbents of heavy metals and dyes

In recent years, nanocellulose-based materials have been increasingly applied as a lot of biosorbents for the treatment of water pollutants due to their large specific surface area, easy modification, environmental friendliness, and reproducibility. In this review, surface modification of nanocellulose-based adsorbents with various effective adsorption groups is described, as well as polymer grafting and hybrid composite fabrication. The adsorption mechanisms involved in the adsorption process of pollutants by adsorbents are further analysed and summarized. The regeneration methods of nanocellulose adsorbents with different adsorption mechanisms are also demonstrated. In addition, this paper also briefly describes the forms of nanocellulose-based adsorbents with large-scale application including membranes, gels, flocculants and magnetic composites.

Suppression of LjBAK1-mediated immunity by SymRK promotes rhizobial infection in Lotus japonicus

An important question in biology is how organisms can associate with different microbes that pose no threat (commensals), pose a severe threat (pathogens), and those that are beneficial (symbionts). The root nodule symbiosis serves as an important model system for addressing such questions in the context of plant-microbe interactions. It is now generally accepted that rhizobia can actively suppress host immune responses during the infection process, analogous to the way in which plant pathogens can evade immune recognition. However, much remains to be learned about the mechanisms by which the host recognizes the rhizobia as pathogens and how, subsequently, these pathways are suppressed to allow establishment of the nitrogen-fixing symbiosis. In this study, we found that SymRK (Symbiosis Receptor-like Kinase) is required for rhizobial suppression of plant innate immunity in Lotus japonicus. SymRK associates with LjBAK1 (BRASSINOSTEROID INSENSITIVE 1-Associated receptor Kinase 1), a well-characterized positive regulator of plant innate immunity, and directly inhibits LjBAK1 kinase activity. Rhizobial inoculation enhances the association between SymRK and LjBAK1 in planta. LjBAK1 is required for the regulation of plant innate immunity and plays a negative role in rhizobial infection in L. japonicus. The data indicate that the SymRK-LjBAK1 protein complex serves as an intersection point between rhizobial symbiotic signaling pathways and innate immunity pathways, and support that rhizobia may actively suppress the host's ability to mount a defense response during the legume-rhizobium symbiosis.

Immunoglobulin D Multiple Myeloma with a “Hidden” Lambda Light Chain

Introduction/Objective

In rare cases, the conventional immunofixation gel electrophoresis technique fails to detect the light chain of an M-protein. We report a case of immunoglobulin (Ig) D multiple myeloma with a hidden lambda (λ) light chain.

Methods/Case Report

Capillary electrophoresis (CE) (Sebia CAPILLARYS 2) was used to detect and quantify M- proteins in serum specimens. Immunosubtraction (IS) on the CAPILLARYS 2 systems was used to identify the classes of M-proteins. Conventional gel immunofixation electrophoresis (IFE) was performed, using monospecific antisera for IgD, IgE, kappa (κ) or λ in the Sebia HYDRASYS system, and IgG, IgA, IgM, κ or λ in the Helena SPIFE3000 system. Beta-mercaptoethanol (BME) with Fluidil were used as reduction agents.

Results (if a Case Study enter NA)

Results of serum CE showed two abnormal peaks in beta 2 and gamma regions, suspected to be positive for M-proteins. IS results showed subtraction for λ light chain only in both peaks, suggesting two monoclonal λ light chains. In contrary, no monoclonal λ light chain was detected in gamma region by IFE (Sebia). Epitope masking in the folded monoclonal protein was suspected to cause the “hidden λ light chain” and was further investigated by two laboratory approaches. IFE performed on the Helena SPIFE3000 system found two λ bands in beta 2 and gamma regions, which was consistent with the results from IS. The treatment of BME with Fluidil helped unmasking the hidden epitope and revealed the λ band in gamma region on IFE (Sebia).

Conclusion

The medical laboratories should be aware of the described scenario. The failure to detect light chains of certain intact M-proteins is most likely due to the structurally inaccessibility of light chains. It is recommended that treatment with reduction agents or use of an alternative methodology or IS might be helpful for investigating suspected heavy chain only cases, due to the limitation of conventional methodology.

Lubricin-Inspired Loop Zwitterionic Peptide for Fabrication of Superior Antifouling Surfaces

Biofouling represents great challenges in many applications, and zwitterionic peptides have been a promising candidate due to their biocompatibility and excellent antifouling performance. Inspired by lubricin, we designed a loop-like zwitterionic peptide and investigated the effect of conformation (linear or loop) on the antifouling properties using a combination of surface plasma resonance (SPR), surface force apparatus (SFA), and all atomistic molecular dynamics (MD) simulation techniques. Our results demonstrate that the loop-like zwitterionic peptides perform better in resisting the adsorption of proteins and bacteria. SFA measurements show that the loop-like peptides reduce the adhesion between the modified surface and the modeling foulant lysozyme. All atomistic MD simulations reveal that the loop-like zwitterionic peptides are more rigid than the linear-like zwitterionic peptides and avoid the penetration of the terminus into the foulants, which lower the interaction between the zwitterionic peptides and foulants. Besides, the loop-like zwitterionic peptides avoid the aggregation of the chains and bind more water, improving the hydrophilicity and antifouling performance. Altogether, this study provides a more comprehensive understanding of the conformation effect of zwitterionic peptides on their antifouling properties, which may contribute to designing novel antifouling materials in various biomedical applications.

[Identification and genetic analysis of new mutations in EYA1 gene of BOS syndrome]

Objective: To analyze the clinical manifestations of a patient with branchiootic syndrome(BOS) and her families and to carry out genetic testing in order to specify the biological pathogenesis. Methods: Clinical data of the patient and her families were collected. Genomic DNA in the peripheral blood of the proband and her family members was extracted. All exons of 406 deafness-related susceptible genes as well as their flanking regions were sequenced by high-throughput sequencing, and the mutation sites of the proband and her parents were validated by Sanger sequencing. Results: There were nine members in three generations, of whom four presented with hearing loss, preauricular fistula and branchial fistula which met the diagnostic criteria of BOS. Proband and her mother presented with auricle malformation and inner ear malformation. And no one had abnormalities in the kidneys of all the patients. Pedigree analysis revealed that the mode of inheritance in the family was consistent with the autosomal dominant pattern. Mutational analysis showed that all the affected patients detected a heterozygous frameshift variation c.1255delT in the EYA1 gene, which had not been reported. Genotype and phenotype were co-isolated in this family. Such a frameshift variation produced a premature termination codon, thereby causing premature termination of translation (p.C419VFS*12). ACMG identified that the mutation was pathogenic. This mutation was novel and not detected in controls. A heterozygous missense variation mutation c.403G>A(p.G135S) in EYA1 gene was also detected in three members of this family. ACMG identified that the mutation clinical significance was uncertain. However, two of whom were normal, which seemed the disease was not caused by this mutation in this family. Conclusions: A novel frameshift mutation in EYA1(c.1255delT) is the main molecular etiology of BOS in the Chinese family. This study expands the mutational spectrum of EYA1 gene. The clinical manifestations are heterogeneous among patients in this family. The diagnosis of BOS should combine gene tests with clinical phenotypes analysis.

Enhanced enzymatic hydrolysis of cellulose by endoglucanase via expansin pretreatment and the addition of zinc ions

One of the major limitations of lignocellulose conversion is the relatively low efficiency of cellulases. Expansins can act as an accessory protein to loosen the rigid cellulose structure and promote cellulose hydrolysis. However, the synergistic action of expansin is not well understood. In this study, we employed quartz crystal microbalance with dissipation to real-time monitor the adsorption of Bacillus subtilis expansin (BsEXLX1) and endoglucanase I (Cel7B) and the hydrolysis of cellulose. The effects of pH, temperature, and zinc ions on the initial adsorption rate and adsorption capacity of BsEXLX1 were examined. When 36.5 mM of zinc ions was added, the irreversible adsorption ratio of BsEXLX1 further increased to 4.63 times the value in the absence of zinc ions, whereas the initial adsorption rate and the hydrolysis rate constants of Cel7B could reach 2.16 times and 2.05 times the values in the absence of zinc ions, respectively.

Association between periodontal disease and prostate cancer: a systematic review and meta-analysis

Background

Periodontal disease is a chronic infectious disease caused by bacterial infection which may lead to various systematic diseases. Recently, increasing studies have explored the correlation of periodontal disease with the risk of prostate cancer. However, the findings were inconsistent. Hence, this study aims to investigate the association between periodontal disease and the risk of prostate cancer by a meta-analysis.

Material and Methods

PubMed, EMBASE, and Cochrane were searched for publications up to July 17, 2020. Cohort and case-control studies evaluating the risk of prostate cancer in patients with periodontal disease were included. A fixed or random-effect model was used to calculate the summary relative risk (RR) along with 95% confidence interval (CI). All analyses were conducted using Stata 12.0 software.

Results

Seven studies were included in the final analysis. The pooled estimates showed that periodontal disease was significantly associated with the risk of prostate cancer (RR = 1.17; 95% CI = 1.07-1.27; P = 0.001). Findings of sensitivity analyses proved that the overall results were robust.

Conclusions

Periodontal disease may be considered as a potential risk factor for prostate cancer. Although it’s a possibility, males should be more aware of their oral health and implement effective measures to prevent and treat periodontal disease.

Key words:Periodontal disease, periodontitis, prostate cancer, meta-analysis

[Effects and mechanisms of polycaprolactone-cellulose acetate nanofiber scaffold loaded with rat epidermal stem cells on wound healing of full-thickness skin defects in rats]

Objective: To explore the effects and mechanisms of polycaprolactone-cellulose acetate (PCL-CA) nanofiber scaffold loaded with rat epidermal stem cells (ESCs) on wound healing of full-thickness skin defects in rats. Methods: The experiment research method was applied. The primary ESCs were isolated from 1-3 d old Sprague-Dawley (SD) rats (undefined gender) by rapid adherent method and cultured by rapid adherent method. ESCs of the first passage were used for the subsequent experiments after the positive expressions of integrin β₁ and cytokeratin 19 (CK19) in primary cells were identified respectively by flow cytometey and immunofluorescence method. PCL-CA nanofiber scaffolds with polycaprolactone and cellulose acetate as components were prepared by electrospinning technique. The topological structure of the nanofiber scaffolds was determined and the diameter of 25 fibers was measured by scanning electron microscope. The constructed PCL-CA nanofiber scaffolds were used as the culture substrate for ESCs, which were cultured in keratinocytes (KCs) medium to construct ESCs-nanofiber scaffold complex (hereinafter referred to as ESCs scaffold). After 3 days of culture, the morphology of ESCs in the scaffold and their relationship was observed by scanning electron microscopy. The ESCs in ESCs scaffold were set as PCL-CA nanofiber scaffold group, and the ESCs cultured with KCs medium in culture dishes coated with type Ⅳ collagen were set as type Ⅳ collagen group. Western blotting was used to detect the protein expression level of CK19 in ESCs in the two groups after 3 days of culture (n=3). The protein expressions of CK19 and proliferating nuclear antigen (PCNA) in ESCs in the two groups were detected by immunofluorescence method after 7 days of culture. A circular full-thickness skin wound of about 2 cm in diameter was prepared on both left and right sides of the back of 15 male SD rats aged 6-8 weeks. The rats were then equally divided into blank control group without implantation, scaffold alone group implanted with PCL-CA nanofiber scaffold, and ESCs scaffold group implanted with ESCs scaffold which were constructed after 3 days of culture according to the random number table. The percentage of wound areas on post injury day (PID) 3, 7, 14, and 21 was calculated (n=5). The new skin tissue at the wound edge was collected on PID 21, the wound healing quality was evaluated by Masson staining, and the protein expression levels of Notch1, Jagged1, and Hes1, which are key proteins of Notch signaling pathway, were detected by Western blotting (n=3). Data were statistically analyzed with one-way analysis of variance, one-way analysis of variance, analysis of variance for repeated measurement, independent sample t test, and Bonferroni correction. Results: The constructed PCL-CA nanofiber scaffolds had a porous, mesh-like, and multilayered three-dimensional structure, in which the surface of the fibers was smooth and non-porous, and the fiber diameter was (383±24) nm. The ESCs in ESCs scaffold showed intact cellular structures and were tightly attached to the scaffold after 3 days of culture. The cells were interconnected and fully extended on the surface of the scaffold to form a membrane. After 3 days of culture, the protein expression level of CK19 of ESCs in PCL-CA nanofiber scaffold group was significantly higher than that in type Ⅳ collagen group (t=24.56, P<0.01). After 7 days of culture, compared with those in type Ⅳ collagen group, there was no significant change in the proportion of PCNA positive cells of ESCs in PCL-CA nanofiber scaffold group, while the proportion of CK19 positive cells was higher. On PID 3, 7, 14, and 21, the percentages of wound areas of rats in ESCs scaffold group were (78.0±1.8)%, (40.9±2.0)%, (17.9±1.1)%, and (5.0±1.0)%, respectively, which were significantly lower than (84.2±1.9)%, (45.4±2.6)%, (21.8±1.7)%, and (10.1±1.1)% in blank control group (t=5.42, 3.09, 4.33, 7.58, P<0.05 or P<0.01) and (82.7±1.2)%, (44.8±2.0)%, (22.4±2.4)%, and (10.3±2.4)% in scaffold alone group (t=4.98, 3.11, 3.84, 4.57, P<0.05 or P<0.01), while the percentages of wound areas of rats between blank control group and scaffold alone group were similar (t=1.47, 0.39, 0.47, 0.22, P>0.05). On PID 21, the layer of new skin at the wound edge of rats in each group was intact; compared with that in blank control group or scaffold alone group, the new skin tissue at the wound edge of rats in ESCs scaffold group had more orderly collagen arrangement; the scaffolds in the new skin at the wound edge of rats were completely degraded in ESCs scaffold group and scaffold alone group. On PID 21, the protein expression levels of Notch1, Jagged1, and Hes1 in the new skin tissue at the wound edge of rats in scaffold alone group were similar to those in blank control group (t=1.70, 1.94, 0.18, P>0.05), while the protein expression levels of Notch1, Jagged1, and Hes1 in the new skin tissue at the wound edge of rats in ESCs scaffold group were significantly higher than those in scaffold alone group (t=13.31, 22.07, 20.71, P<0.01). Conclusions: PCL-CA nanofiber scaffolds can inhibit the differentiation of ESCs of rats without affecting their proliferation in vitro. ESCs scaffolds constructed through using PCL-CA nanofiber scaffolds as the carrier to culture ESCs of rats can significantly promote the wound healing of full-thickness skin defects in rats, and the mechanism may be related to the activation of Notch signaling pathway.

[Aryl hydrocarbon receptor modulates airway inflammation in mice with cockroach allergen-induced asthma by regulating Th17/Treg differentiation]

OBJECTIVE

To investigate whether aryl hydrocarbon receptor (AhR) modulates cockroach allergen (CRE)-induced asthma by regulating Th17/Treg differentiation.

OBJECTIVE

Mouse models of CRE-induced asthma established by sensitizing and challenging the mice with CRE were randomized into asthma model group, AhR agonist group treated with TCDD (10 μg/ kg), and AhR antagonist group treated with TCDD and CH223191 (10 mg/kg) (n=5), with 5 mice without CRE challenge as the control group. The expressions of AhR, Cyp1a1 and Cyp1b1 mRNA in the lung tissues of the mice were detected using RT-PCR, and pulmonary inflammation was evaluated with immumohistochemical staining. The expressions of inflammatory cytokines in the lungs were detected using ELISA, and the expression of Treg in the lung tissues and pulmonary lymph nodes was analyzed with flow cytometry.

OBJECTIVE

Both TCDD and CH223191 were capable of modulating pulmonary expressions of AhR and its downstream genes Cyp1a1 and Cyp1b1 in asthmatic mice (P < 0.002). TCDD treatment significantly decreased inflammatory cells and mucus production in the lungs of asthmatic mice, and BALFs from TCDD-treated mice with CRE challenge contained lowered levels of the proinflammatory factors including IL-4, IL-13 and IL-17A (P < 0.001) but increased anti-inflammatory factors including IL-10, IL-22 and TGF-β1 (P < 0.001). All these changes were significantly reversed by treatment with CH223191 to the levels comparable with those in the asthma model group (P>0.05). More importantly, TCDD treatment significantly increased the number of Tregs cells and FOXP3 expression and lowered RORγt mRNA expression in the lungs and pulmonary lymph nodes in asthmatic mice (P < 0.001); inhibition of AhR with CH223191, as compared with TCDD, significantly decreased the expression of CD4⁺CD25⁺Foxp3⁺Treg cells in the lungs and pulmonary lymph nodes and the expression of FOXP3 mRNA in lymphocytes and increased RORγt mRNA expression (P < 0.001) to the levels comparable with those in asthma model group (P>0.05).

OBJECTIVE

AhR activation modulates airway inflammation in mice with CRE-induced asthma by modulating the differentiation of Th17/Treg.