Live-attenuated vaccine sCPD9 elicits superior mucosal and systemic immunity to SARS-CoV-2 variants in hamsters

Vaccines play a critical role in combating the COVID-19 pandemic. Future control of the pandemic requires improved vaccines with high efficacy against newly emerging SARS-CoV-2 variants and the ability to reduce virus transmission. Here we compare immune responses and preclinical efficacy of the mRNA vaccine BNT162b2, the adenovirus-vectored spike vaccine Ad2-spike and the live-attenuated virus vaccine candidate sCPD9 in Syrian hamsters, using both homogeneous and heterologous vaccination regimens. Comparative vaccine efficacy was assessed by employing readouts from virus titrations to single-cell RNA sequencing. Our results show that sCPD9 vaccination elicited the most robust immunity, including rapid viral clearance, reduced tissue damage, fast differentiation of pre-plasmablasts, strong systemic and mucosal humoral responses, and rapid recall of memory T cells from lung tissue after challenge with heterologous SARS-CoV-2. Overall, our results demonstrate that live-attenuated vaccines offer advantages over currently available COVID-19 vaccines.

Deciphering the Role of Humoral and Cellular Immune Responses in Different COVID-19 Vaccines-A Comparison of Vaccine Candidate Genes in Roborovski Dwarf Hamsters

With the exception of inactivated vaccines, all SARS-CoV-2 vaccines currently used for clinical application focus on the spike envelope glycoprotein as a virus-specific antigen. Compared to other SARS-CoV-2 genes, mutations in the spike protein gene are more rapidly selected and spread within the population, which carries the risk of impairing the efficacy of spike-based vaccines. It is unclear to what extent the loss of neutralizing antibody epitopes can be compensated by cellular immune responses, and whether the use of other SARS-CoV-2 antigens might cause a more diverse immune response and better long-term protection, particularly in light of the continued evolution towards new SARS-CoV-2 variants. To address this question, we explored immunogenicity and protective effects of adenoviral vectors encoding either the full-length spike protein (S), the nucleocapsid protein (N), the receptor binding domain (RBD) or a hybrid construct of RBD and the membrane protein (M) in a highly susceptible COVID-19 hamster model. All adenoviral vaccines provided life-saving protection against SARS-CoV-2-infection. The most efficient protection was achieved after exposure to full-length spike. However, the nucleocapsid protein, which triggered a robust T-cell response but did not facilitate the formation of neutralizing antibodies, controlled early virus replication efficiently and prevented severe pneumonia. Although the full-length spike protein is an excellent target for vaccines, it does not appear to be the only option for future vaccine design.

Favorable therapeutic response after anti-Mesothelin antibody-drug conjugate treatment requires high expression of Mesothelin in tumor cells

PURPOSE

The cell surface glycoprotein Mesothelin is overexpressed in ovarian, fallopian tube, endometrial, cervical and primary peritoneal cancer and, therefore, might become a particular interesting tumor target in gynecologic oncology. However, even in malignant tumors of the same entity the level of Mesothelin expression varies between individuals, hence it can be expected that the response to Mesothelin-targeting therapies will be variable as well. In this study we explored the therapeutic potency of a novel anti-Mesothelin antibody-drug conjugate (Anetumab ravtansine) as a function of Mesothelin expression in the targeted tumor cells.

METHODS

Anti-tumor activity studies were performed in human uterine xenograft tumor models that express Mesothelin at high, moderate or low levels. The antibody-drug conjugate (ADC) was applied in varying doses ranging from 2 to 15 mg/kg at variable intervals in tumor bearing SCID/beige mice and the impact on tumor growth was monitored.

RESULTS

The therapeutic response to the anti-Mesothelin ADC correlated closely with the level of Mesothelin expression in tumor cells. Within the applied dose levels complete tumor regression was achieved only in tumors which expressed Mesothelin at particularly high levels (Hela cell tumors). The application of high anti-Mesothelin ADC doses less frequently was more efficious than giving lower doses at a higher frequency.

CONCLUSION

The studies confirm the great therapeutic potential of Anetumab ravtansine. However, a favorable treatment outcome requires strong Mesothelin expression in tumor cells. Future clinical trials may benefit from a more rigorous selection of appropriate patients based on the level of Mesothelin expression in their tumor tissue. If, in addition, it is possible to better control side effects by introducing protective measures and by doing so to increase the maximum tolerated dose, Anetumab ravtansine has the potency to become a valuable therapeutic tool, especially in the field of gynecological oncology.

Establishment of a Mucin Secreting Cell Line Cx-03 from an Uterine Carcino Sarcoma

PURPOSE

The identification of novel cell lines which combine the most important properties of mucosal membranes in terms of drug absorption, transmembrane transport and mucus secretion can help to establish improved and meaningful test systems for pharmacological and infectiological studies.

METHODS

We have established a novel mucus secreting tumor cell line (Cx-03) derived from a female patient who underwent radical hysterectomy after diagnosis of a large malignant carcino sarcoma (Muellerian mixed tumor). Via xenotransplantation in SCID beige mice, recultivation and subcloning a stable cell line was established from primary tumor cells.

RESULTS

Human origin and novelty of the cell line was determined by karyotype analysis and STR fingerprint. During growth cells produce considerable amounts of a PAS positive viscoelastic mucus. Immunostaining revealed expression of mucins and the mucin modifier CLCA1. We demonstrate in initial electrophysiological experiments that confluent, polarized monolayers of Cx-03 are formed (on PCF-filter supports) that exhibit stable electrical resistance (> 600 Ω cm²). Confluent Cx-03 monolayers express barrier-forming tight junction proteins claudin-1 and -4 which co-localize with zonula occludens protein-1 (ZO-1) at cell-cell contacts.

CONCLUSIONS

Mucus secretion is a rare property among mammalian cell lines. In combination with its ability to form polarized monolayers Cx-03 might contribute as a novel cell based model for drug absorption, transport and barrier studies.

Transperineal ultrasound imaging in prolonged second stage of labor with occipitoanterior presenting fetuses: how well does the 'angle of progression' predict the mode of delivery?

OBJECTIVES

To compare the angle of progression on transperineal ultrasound imaging between different modes of delivery in prolonged second stage of labor with occipitoanterior fetal position.

METHODS

We prospectively evaluated 41 women at term (>or= 37 weeks) with failure to progress in the second stage of labor. Only cases with occipitoanterior fetal position were included in the final analysis. These cases were classified into three groups: Cesarean section for failure to progress, vacuum extraction for failure to progress, and spontaneous delivery following prolonged second stage of labor. Transperineal ultrasound examination was performed just before digital examination and subsequent delivery. The angle between a line placed through the midline of the pubic symphysis and a line running from the inferior apex of the symphysis tangentially to the fetal skull (the so-called 'angle of progression') was measured offline by an observer blinded to the mode of delivery.

RESULTS

There were 26 cases with occipitoanterior fetal position (Cesarean section, n = 5; vacuum extraction, n = 16; spontaneous delivery, n = 5). Logistic regression analysis showed a strong relationship between the angle of progression and the need for Cesarean delivery (R(2) measure of fit = 55%, likelihood ratio chi-square P < 0.0001). When the angle of progression was 120 degrees , the fitted probability of either an easy and successful vacuum extraction or spontaneous vaginal delivery was 90%.

CONCLUSIONS

This is the first report to document a strong relationship between an objective ultrasound marker (angle of progression) and the mode of delivery following prolonged second stage of labor with occipitoanterior fetal position. A predictive model using this parameter would allow better decision making regarding operative delivery for obstructed labor.

A sensitive noninvasive method for monitoring successful liver-directed gene transfer of the low-density lipoprotein receptor in Watanabe hyperlipidemic rabbits in vivo

Noninvasive tools to quantitate transgene expression directly are a prerequisite for clinical gene therapy. We established a method to determine location, magnitude, and duration of low-density lipoprotein (LDL) receptor (LDLR) transgene expression after adenoviral gene transfer into LDLR-deficient Watanabe hypercholesterolemic rabbits by following tissue uptake of intravenously injected (111)In-labeled LDL using a scintillation camera. Liver-specific tracer uptake was calculated by normalizing the counts measured over the liver to counts measured over the heart that represent the circulating blood pool of the tracer (liver/heart (L/H) ratio). Our results indicate that the optimal time point for transgene imaging is 4 h after the tracer injection. Compared with control virus-injected rabbits, animals treated with the LDLR-expressing adenovirus showed seven-fold higher L/H ratios on day 6 after gene transfer, and had still 4.5-fold higher L/H ratios on day 30. This imaging method might be a useful strategy to obtain reliable data on functional transgene expression in clinical gene therapy trials of familial hypercholesterolemia.

Titer determination of Ad5 in blood: a cautionary note

Recombinant adenoviruses are presently the most efficient in vivo gene transfer system available. Targeting single organs or large tumors by adenoviral vectors requires an intravascular route of application. During the first pass of viral particles through the vascular bed of the target tissue, virus uptake is not quantitative and indefinite amounts of particles leak into circulation. To determine the amount of leaking particles and to calculate organ-specific uptake (in-/outflow ratio), it is necessary to titrate virus particles directly in blood. In preclinical and clinical trials titration is currently mostly done with blood plasma instead of full blood. However, this technique provides valid results only as long as there is no affinity between adenovirus particles and erythrocytes. In this study we demonstrate that Ad5 particles, as mostly employed for gene therapy, have a strong affinity to human erythrocytes. At 60 min after coincubation of human erythrocytes and Ad5 particles, more than 98% of the particles are attached to the surface of erythrocytes. Therefore, ignoring the amount of red cell bound particles by performing titration in plasma leads to severe miscalculation of organ-specific transfer rates or virus circulation half-life. The biological impact of an increased affinity between virus particles and erythrocytes will be discussed.

Complement activation by recombinant adenoviruses

Recombinant adenoviruses are currently the most important vector system in gene therapy. Adenoviruses frequently cause upper respiratory tract infections in humans and anti-adenoviral antibodies are found in 35-70% of the population. Therefore in the majority of potential patients receiving adenoviral gene therapy, the contact of virus particles and blood will lead to the formation of antigen-antibody complexes. These complexes have the ability to induce inflammatory reactions via an activation of the complement system. We have determined the level of C3a (the most reactive complement component) generated in isolated citrate plasma of healthy individuals after challenge with recombinant and wild-type adenoviruses in amounts corresponding to virus blood levels to be expected in patients during adenoviral gene therapy. All plasma samples containing anti-adenoviral antibodies showed a substantial, dose-dependent generation of C3a. A virus plasma level of about 7.5 x 10(9) particles/ml (which was calculated to be the highest blood level reached during clinical trials in the past) induced an average release of about 3000 ng/ml C3a (baseline levels <140 ng/ml). Analyzing the nature of anti-adenoviral antibodies showed, that not only antibodies with neutralizing properties (anti-Ad5), but also non-neutralizing anti-adenoviral antibodies are capable of complement activation. This study suggests that complement activation can be ignored in local low-dose applications of recombinant adenoviruses, but warrants attention after systemic application of large viral quantities. In clinical protocols aiming at systemic virus application, measures for monitoring and controlling the complement system should be included on a regular basis.

Emerging therapies in hepatology: liver-directed gene transfer and hepatocyte transplantation

Gene transfer and epithelial cell transplantation technologies play an important role in the development of new therapeutic concepts for liver diseases. Although liver organ transplantation has revolutionized the treatment of a wide spectrum of acute and chronic liver diseases, gene- and cell-based therapies are emerging at an astonishing pace, because they promise to be less invasive, less costly and at least as effective as currently established therapy protocols. Experimental gene therapy models have been developed for a wide spectrum of liver diseases, including hereditary liver disorders, malignant liver disease and viral hepatitis. Hepatocyte transplantation (HcTx) is being explored as treatment of severe chronic and acute liver failure as well as for hereditary liver diseases. Most of these procedures and techniques are still experimental or have been applied to a small number of patients only. Rigorous clinical evaluation will finally demonstrate the usefulness of each new procedure in the daily clinical care of patients with liver disease. In this review, we have attempted to provide an introduction and survey of the topics of gene therapy and HcTx with specific examples of laboratory and clinical achievements highlighting potential applications in liver diseases.

Nonphysiological overexpression of low-density lipoprotein receptors causes pathological intracellular lipid accumulation and the formation of cholesterol and cholesteryl ester crystals in vitro

Recent therapeutic strategies for the treatment of familial hypercholesterolemia have been based on liver-directed gene transfer of a functional low-density lipoprotein (LDL) receptor cDNA under control of viral or strong housekeeping promoters. Strong viral promoters including cytomegalovirus, Rous sarcoma virus, and simian virus 40 promoters are commonly employed to reach significant physiological effects. These promoters mediate constitutive and nonphysiological overexpression in every transduced cell, while the endogenous LDL receptor expression is controlled by a complex feedback mechanism based on intracellular cholesterol concentration. To investigate intracellular consequences of persistent LDL receptor overexpression we constructed a recombinant adenovirus encoding the human LDL receptor under control of the Rous sarcoma virus promoter. The metabolic and morphological effects of LDL receptor expression were characterized by uptake experiments with human hepatoma cells using fluorescent and radiolabeled LDL. We observed that large amounts of LDL accumulate within LDL receptor transduced cells, which eventually lead to massive intracellular lipid deposition. Kinetic experiments with LDL-supplemented medium resulted in numerous crystal shaped structures in the cytosol of transduced cells as visualized by digital interference contrast optic within 60 min after LDL supplementation. Thin layer chromatography analyses of cellular lipids suggested these crystalline structures to be dependent on intracellular cholesterol and cholesterol ester levels. Mock-infected cells showed neither cholesterol lipid accumulation nor crystal formation. In conclusion, our data demonstrate that nonphysiological overexpression of the LDL receptor can cause massive lipid accumulation, which cannot be compensated by the hepatoma cell metabolism. This phenomenon may result in negative selection of LDL receptor overexpressing cells in vitro and in vivo.

Intravenous administration of recombinant adenoviruses causes thrombocytopenia, anemia and erythroblastosis in rabbits

BACKGROUND

Recombinant adenoviruses are highly efficient gene transfer vehicles but their administration to mammals is accompanied by a strong inflammatory response. The present study reports additional side effects observed during adenoviral gene transfer studies in rabbits.

METHODS

Hematological and serological parameters, the course of viremia and the organ distribution were analyzed after in vivo administration of E1-deleted adenoviruses in rabbits.

RESULTS

The systemic administration of a therapeutic dose of 5 x 10(11) infectious particles/kg (infusion time 20 min) led to an average reduction of 80-90% in the platelet count within 48 h. Full recovery took 10-14 days. Virus administration induced a strong but transient erythroblastosis (peaking 24 h after administration) which settled 48 h later. Normochromic anemia occurred over the next 10 days with hemoglobin levels dropping by about 40% to reach the lowest level 10 days after administration and taking two months for full recovery. Dose-dependent thrombocytopenia was also found in mice, but neither erythroblastosis nor anemia was observed (in equivalent doses). The hematological findings did not improve after local injection via the portal vein. Local and systemic administration led to a comparable course of viremia. Only minor differences were found in the biodistribution of viruses between local and systemic administration. Large amounts of viral DNA and transgene expression were found in the lungs, the kidneys and the ovaries, even after local administration via the portal vein.

CONCLUSIONS

Local intravenous injection via the portal vein does not prevent systemic spread of viral vectors and the occurrence of vector-related side effects. The hematological changes observed in rabbits suggest the need for careful monitoring of hematological and rheological parameters in clinical trials.

Ovine adenovirus vectors overcome preexisting humoral immunity against human adenoviruses in vivo

Recombinant human adenoviruses (hAd) have become widely used as tools to achieve efficient gene transfer. However, successful application of hAd-derived vectors in clinical trials is limited due to immunological and potential safety problems inherent in their human origin. In this study, we describe a recombinant ovine adenovirus (OAV) as an alternative vector for gene transfer in vivo. In contrast to an hAd vector, the OAV vector was not neutralized by human sera. An OAV vector which contained the cDNA of the human alpha1-antitrypsin (hAAT) gene linked to the Rous sarcoma virus promoter was generated and administered systemically to mice. The level and duration of hAAT gene expression was similar to that achieved with an hAd counterpart in both immunocompetent and immunodeficient mice. However, the tissue distribution of the OAV vector differed from that observed for hAd vectors in that the liver was not the dominant target. Significantly, we demonstrated efficient gene transfer with the OAV vector into mice immunized with hAd vectors and vice versa. We also confirm that the immune response to a transgene product can prevent its functional expression following sequential application of a vector. Our results suggest a possible solution to endemic humoral immunity against currently used hAd vectors and should therefore have an impact on the design of improved gene therapy protocols utilizing adenovirus vectors.

Transient immunosuppression with 15-deoxyspergualin prolongs reporter gene expression and reduces humoral immune response after adenoviral gene transfer

A strong immune response against transgenic cells is one important limitation for long-term expression after adenoviral gene transfer in mammals. Continuous pharmacological immunosuppression has been shown to ameliorate immune reactions and to prolong reporter gene expression. In this study, we explored the effect of short-term immunosuppression for long-term gene expression and its impact on antibody formation. Immunosuppression with FK 506 (1 mg/kg/day), cyclosporin A (20 mg/kg/day) and 15-deoxyspergualin (10 mg/kg/day) was performed in NMRI mice. Expression of the reporter gene human alpha-1-antitrypsin (hAAT) and antibody formation was monitored for 7 months. A 5-day course of 15-deoxyspergualin (15-DSG) markedly slowed the decline of reporter gene expression and a positive effect was still detectable 200 days after gene transfer. At the same time, antibody production was reduced by 50-60%. Continuous treatment with 15-DSG (10 mg/kg twice weekly) led to a further small increase of gene expression but reduced antibody formation by 80-90%. A short course of FK 506 and cyclosporin A (CsA), had conferred a negative effect on gene expression. Both groups showed an even faster reduction in gene expression compared with the control group. The results of this investigation suggest that 15-DSG could serve as an effective supplement for viral gene therapy protocols.

Receptor-mediated action of hepoxilin A3 releases diacylglycerol and arachidonic acid from human neutrophils

We have previously shown that hepoxilin A3 increases the intracellular concentration of Ca+2 in human neutrophils. Herein we address the initial events of hepoxilin action on the neutrophil which precede the rise in intracellular calcium. We show that hepoxilin A3 at 10-1000 nM concentrations releases from [1-14C]-arachidonic acid labeled neutrophils diacylglycerol and unesterified arachidonic acid in a time and concentration dependent fashion. The release of arachidonic acid and diacyglycerol are receptor-mediated events which are blocked by pertussis toxin. This data shows that hepoxilin A3 stimulates phospholipases C and A2 in the cell which may be involved in the rise in cytosolic calcium. Thus, hepoxilins may represent a hitherto unrecognised class of cellular mediators.