Plant-derived Durvalumab variants show efficient PD-1/PD-L1 blockade and therapeutically favourable FcR binding

Immune checkpoint blocking therapy targeting the PD-1/PD-L1 inhibitory signalling pathway has produced encouraging results in the treatment of a variety of cancers. Durvalumab (Imfinzi®) targeting PD-L1 is currently used for immunotherapy of several tumour malignancies. The Fc region of this IgG1 antibody has been engineered to reduce FcγR interactions with the aim of enhancing blockade of PD-1/PD-L1 interactions without the depletion of PD-L1-expressing immune cells. Here, we used Nicotiana benthamiana to produce four variants of Durvalumab (DL): wild-type IgG1 and its 'Fc-effector-silent' variant (LALAPG) carrying further modifications to increase antibody half-life (YTE); IgG4S228P and its variant (PVA) with Fc mutations to decrease binding to FcγRI. In addition, DL variants were produced with two distinct glycosylation profiles: afucosylated and decorated with α1,6-core fucose. Plant-derived DL variants were compared to the therapeutic antibody regarding their ability to (i) bind to PD-L1, (ii) block PD-1/PD-L1 inhibitory signalling and (iii) engage with the neonatal Fc receptor (FcRn) and various Fcγ receptors. It was found that plant-derived DL variants bind to recombinant PD-L1 and to PD-L1 expressed in gastrointestinal cancer cells and are able to effectively block its interaction with PD-1 on T cells, thereby enhancing their activation. Furthermore, we show a positive impact of Fc amino acid mutations and core fucosylation on DL's therapeutic potential. Compared to Imfinzi®, DL-IgG1 (LALAPG) and DL-IgG4 (PVA)S228P show lower affinity to CD32B inhibitory receptor which can be therapeutically favourable. Importantly, DL-IgG1 (LALAPG) also shows enhanced binding to FcRn, a key determinant of serum half-life of IgGs.

The ligand-dependent suppression of TCR signaling by the immune checkpoint receptor LAG3 depends on the cytoplasmic RRFSALE motif

Lymphocyte activation gene 3 (LAG3) is an inhibitory immune checkpoint receptor that restrains autoimmune and antitumor responses, but its evolutionarily conserved cytoplasmic tail lacks classical inhibitory motifs. Major histocompatibility complex class II (MHC class II) is an established LAG3 ligand, and fibrinogen-like protein 1 (FGL1), lymph node sinusoidal endothelial cell C-type lectin (LSECtin), and Galectin-3 have been proposed as alternative binding partners that play important roles in LAG3 function. Here, we used a fluorescent human T cell reporter system to study the function of LAG3. We found that LAG3 reduced the response to T cell receptor stimulation in the presence of MHC class II molecules to a lesser extent compared with the receptor programmed cell death protein 1. Analysis of deletion mutants demonstrated that the RRFSALE motif in the cytoplasmic tail of LAG3 was necessary and sufficient for LAG3-mediated inhibition. In this system, FGL1, but not LSECtin or Galectin-3, acted as a LAG3 ligand that weakly induced inhibition. LAG3-blocking antibodies attenuated LAG3-mediated inhibition in our reporter cells and enhanced reporter cell activation even in the absence of LAG3 ligands, indicating that they could potentially enhance T cell responses independently of their blocking effect.

Engineered soluble, trimerized 4-1BBL variants as potent immunomodulatory agents

Targeting co-stimulatory receptors promotes the activation and effector functions of anti-tumor lymphocytes. 4-1BB (CD137/TNFSF9), a member of the tumor necrosis factor receptor superfamily (TNFR-SF), is a potent co-stimulatory receptor that plays a prominent role in augmenting effector functions of CD8+ T cells, but also CD4+ T cells and NK cells. Agonistic antibodies against 4-1BB have entered clinical trials and shown signs of therapeutic efficacy. Here, we have used a T cell reporter system to evaluate various formats of 4-1BBL regarding their capacity to functionally engage its receptor. We found that a secreted 4-1BBL ectodomain harboring a trimerization domain derived from human collagen (s4-1BBL-TriXVIII) is a strong inducer of 4-1BB co-stimulation. Similar to the 4-1BB agonistic antibody urelumab, s4-1BBL-TriXVIII is very potent in inducing CD8+ and CD4+ T cell proliferation. We provide first evidence that s4-1BBL-TriXVIII can be used as an effective immunomodulatory payload in therapeutic viral vectors. Oncolytic measles viruses encoding s4-1BBL-TriXVIII significantly reduced tumor burden in a CD34+ humanized mouse model, whereas measles viruses lacking s4-1BBL-TriXVIII were not effective. Natural soluble 4-1BB ligand harboring a trimerization domain might have utility in tumor therapy especially when delivered to tumor tissue as systemic administration might induce liver toxicity.

In planta deglycosylation improves the SARS-CoV-2 neutralization activity of recombinant ACE2-Fc

SARS-CoV-2 infects human cells via binding of the viral spike glycoprotein to its main cellular receptor, angiotensin-converting enzyme 2 (ACE2). The spike protein-ACE2 receptor interaction is therefore a major target for the development of therapeutic or prophylactic drugs to combat coronavirus infections. Various engineered soluble ACE2 variants (decoys) have been designed and shown to exhibit virus neutralization capacity in cell-based assays and in vivo models. Human ACE2 is heavily glycosylated and some of its glycans impair binding to the SARS-CoV-2 spike protein. Therefore, glycan-engineered recombinant soluble ACE2 variants might display enhanced virus-neutralization potencies. Here, we transiently co-expressed the extracellular domain of ACE2 fused to human Fc (ACE2-Fc) with a bacterial endoglycosidase in Nicotiana benthamiana to produce ACE2-Fc decorated with N-glycans consisting of single GlcNAc residues. The endoglycosidase was targeted to the Golgi apparatus with the intention to avoid any interference of glycan removal with concomitant ACE2-Fc protein folding and quality control in the endoplasmic reticulum. The in vivo deglycosylated ACE2-Fc carrying single GlcNAc residues displayed increased affinity to the receptor-binding domain (RBD) of SARS-CoV-2 as well as improved virus neutralization activity and thus is a promising drug candidate to block coronavirus infection.

Reteplase Fc-fusions produced in N. benthamiana are able to dissolve blood clots ex vivo

Thrombolytic and fibrinolytic therapies are effective treatments to dissolve blood clots in stroke therapy. Thrombolytic drugs activate plasminogen to its cleaved form plasmin, a proteolytic enzyme that breaks the crosslinks between fibrin molecules. The FDA-approved human tissue plasminogen activator Reteplase (rPA) is a non-glycosylated protein produced in E. coli. rPA is a deletion mutant of the wild-type Alteplase that benefits from an extended plasma half-life, reduced fibrin specificity and the ability to better penetrate into blood clots. Different methods have been proposed to improve the production of rPA. Here we show for the first time the transient expression in Nicotiana benthamiana of rPA fused to the immunoglobulin fragment crystallizable (Fc) domain on an IgG1, a strategy commonly used to improve the stability of therapeutic proteins. Despite our success on the expression and purification of dimeric rPA-Fc fusions, protein instability results in high amounts of Fc-derived degradation products. We hypothesize that the "Y"- shape of dimeric Fc fusions cause steric hindrance between protein domains and leads to physical instability. Indeed, mutations of critical residues in the Fc dimerization interface allowed the expression of fully stable rPA monomeric Fc-fusions. The ability of rPA-Fc to convert plasminogen into plasmin was demonstrated by plasminogen zymography and clot lysis assay shows that rPA-Fc is able to dissolve blood clots ex vivo. Finally, we addressed concerns with the plant-specific glycosylation by modulating rPA-Fc glycosylation towards serum-like structures including α2,6-sialylated and α1,6-core fucosylated N-glycans completely devoid of plant core fucose and xylose residues.

Generation of enzymatically competent SARS-CoV-2 decoy receptor ACE2-Fc in glycoengineered Nicotiana benthamiana

Human angiotensin-converting enzyme 2 (ACE2) is the primary host cell receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) binding and cell entry. Administration of high concentrations of soluble ACE2 can be utilized as a decoy to block the interaction of the virus with cellular ACE2 receptors and potentially be used as a strategy for treatment or prevention of coronavirus disease 2019. Human ACE2 is heavily glycosylated and its glycans impact on binding to the SARS-CoV-2 spike protein and virus infectivity. Here, we describe the production of a recombinant soluble ACE2-fragment crystallizable (Fc) variant in glycoengineered Nicotiana benthamiana. Our data reveal that the produced dimeric ACE2-Fc variant is glycosylated with mainly complex human-type N-glycans and functional with regard to enzyme activity, affinity to the SARS-CoV-2 receptor-binding domain, and wild-type virus neutralization.

The Instability of Dimeric Fc-Fusions Expressed in Plants Can Be Solved by Monomeric Fc Technology

The potential therapeutic value of many proteins is ultimately limited by their rapid in vivo clearance. One strategy to limit clearance by metabolism and excretion, and improving the stability of therapeutic proteins, is their fusion to the immunoglobulin fragment crystallizable region (Fc). The Fc region plays multiple roles in (i) dimerization for the formation of "Y"-shaped structure of Ig, (ii) Fc-mediated effector functions, (iii) extension of serum half-life, and (iv) a cost-effective purification tag. Plants and in particular Nicotiana benthamiana have proven to be suitable expression platforms for several recombinant therapeutic proteins. Despite the enormous success of their use for the production of full-length monoclonal antibodies, the expression of Fc-fused therapeutic proteins in plants has shown limitations. Many Fc-fusion proteins expressed in plants show different degrees of instability resulting in high amounts of Fc-derived degradation products. To address this issue, we used erythropoietin (EPO) as a reporter protein and evaluated the efforts to enhance the expression of full-length EPO-Fc targeted to the apoplast of N. benthamiana. Our results show that the instability of the fusion protein is independent from the Fc origin or IgG subclass and from the peptide sequence used to link the two domains. We also show that a similar instability occurs upon the expression of individual heavy chains of monoclonal antibodies and ScFv-Fc that mimic the "Y"-shape of antibodies but lack the light chain. We propose that in this configuration, steric hindrance between the protein domains leads to physical instability. Indeed, mutations of critical residues located on the Fc dimerization interface allowed the expression of fully stable EPO monomeric Fc-fusion proteins. We discuss the limitations of Fc-fusion technology in N. benthamiana transient expression systems and suggest strategies to optimize the Fc-based scaffolds on their folding and aggregation resistance in order to improve the stability.

Measles vaccination coverage and seroprevalence of anti-measles antibody in south-east Islamic Republic of Iran

Discrepancies often exist between recorded immunization coverage and the real immunity level in a community. To estimate the vaccination coverage against measles in south-east Islamic Republic of Iran, a crosssectional study was conducted in 3 districts during summer 2011. Using probability proportional to size cluster sampling, 1368 children aged 30-54 months were selected. Serum samples of 663 who had received 2 injections of mumpsmeasles- rubella (MMR) vaccine were checked for anti-measles IgG. Vaccination coverage for the second dose of MMR vaccine was 93.7%. The prevalence of anti-measles IgG in those who had received at least 2 MMR vaccine doses was 94.6%. There was a statistically significant association between the serological results and variables that reflected poor accessibility to health services. Combining serological results with coverage data, the proportion of the community protected against measles was estimated as 88.6%, which was below the limits defined for the measles elimination goals.

Toxicity of entomopathogenic fungi, Beauveria bassiana and Lecanicillium muscarium against a field-collected strain of the German cockroach Blattella germanica (L.) (Dictyoptera: Blattellidae)

The German cockroach, Blattella germanica (L.) has been recognized as a serious health problem throughout the world. Control failures due to insecticide resistance and chemical contamination of environment have led some researchers focus on the other alternative strategy controls. Microbial insecticides such as those containing entomo pathogenic fungi could be of high significance. Lecanicillium muscarium and Beauveria bassiana grow naturally in soils throughout the world and act as a parasite on various arthropod species, causing white muscardine disease. Thus, these two species could be considered as entomopathogenic fungi. The current study conducted to evaluate the toxicity of Beauveria bassiana and Lecanicillium muscarium against German cockroach, Blattella germanica. Conidial formulations of L. muscarium (PTCC 5184) and B. bassiana (PTCC5197) were prepared in aqueous suspensions with Tween 20. Bioassays were performed using two methods including submersion of cockroaches in conidial suspension and baiting. Data were analyzed by Probit program and LC50 and LC90 were estimated. The obtained results indicated that both fungi species were toxic against German cockroach however; Beauveria bassiana was significantly 4.8 fold more toxic than L. muscarium against German cockroach using submersion method.

Seroprevalence of poliovirus antibodies among 7-month-old infants after 4 doses of oral polio vaccine in Sistan-va-Baluchestan, Islamic Republic of Iran

Despite high coverage rates of polio vaccine in the Islamic Republic of Iran, the seroconversion rates of infants may be inadequate. This study measured seroprevalence of antibodies against poliovirus serotypes 1 to 3 (PV1, PV2 and PV3) in 7-month-old infants who had received at least 4 doses of trivalent oral polio vaccine. A serosurvey was conducted in 2010 in rural areas of Chabahar, Sistan-va-Baluchestan province. Using cluster sampling, 72 eligible infants were tested for antibody against the 3 poliovirus serotypes according to WHO guidelines. Antibody titres ≥ 1:10 were considered positive. The seropositive rates for antibody against PV1, PV2 and PV3 were 84.7%, 95.8% and 70.8% respectively. Only 63.9% of participants were seropositive for antibodies against all 3 poliovirus serotypes. Except for PV2, the seroprevalence of antibody against the other 2 poliovirus serotypes, especially PV3, was unsatisfactory.

Production of low-fat shrimps by using hydrocolloid coatings

Production of low-fat fried foods by using hydrocolloid coatings is a common method to avoid excessive oil absorption during deep-fat frying. The aim of this work was to evaluate the influence of hydrocolloid coatings (carboxymethyl cellulose, guar, tragacanth and zedo gum) on the oil content and quality parameters of shrimp after deep-fat frying. The hydrocolloid solutions (0.5, 1.0 and 1.5 % w/v) were used for coating. Coated and uncoated (control) samples were packaged and stored at -20 and after a week were fried at 170 °C for 90 s in sunflower oil. The results showed that all hydrocolloid coatings reduced oil content of fried shrimp. The coated shrimps with 1.5 % tragacanth solution had highest coating pick up and moisture content, and lowest oil content than the other samples. The coated samples had darker color and softer texture than the control sample. Sensory evaluation indicated that all coated and uncoated shrimps were acceptable.

Risk of polio reintroduction to border regions of Islamic Republic of Iran: seroprevalence study of children with at least 5 doses of oral polio vaccine

Movements of populations from countries where polio has not been eradicated is a concern in the Islamic Republic of Iran. A cross-sectional, community-based study was implemented in 2010 in 2 districts in Sistan-va-Baluchestan Province near the south-east border. The aim was to determine the seroprevalence of antibodies in children aged 20 (± 2) months who had received at least 5 doses of trivalent oral polio vaccine. Using cluster sampling, 365 children were enrolled for serological testing. Antibody titres ≥ 1:10 were considered positive. Seropositive rates for antibody against poliovirus serotypes 1, 2 and 3 were 94.1%, 96.7% and 78.3% respectively. The lowest seropositive rate was for antibody against polio serotype 3 (PV3) among boys (58.3%). Exclusive breastfeeding showed a direct relationship with antibody response to PV3 (OR = 2.0; 95% CI: 1.1-3.6). Improving community protection against PV3 is an urgent programme priority.

Causes of new cases of major thalassemia in sistan and balouchistan province in South-East of iran

BACKGROUND

Thalassemia is the most common monogenic disease in South-East of Iran. Despite the 70% reduction in Iranian thalassemia cases after thalassemia control comprehensive program, 601 affected babies were born in Sistan and Balouchistan Province, Iran from 2002 to 2010, so this study aims at investigating the causes of new thalassemia cases.

METHODS

Data from this retrospective cross-sectional study was collected through interviews and information in the patients' hospital records.

RESULTS

Data revealed that 52.4% of fathers and 78.4% of mothers of thalassemic children had elementary education or less. In addition, 78.6% of the couples did not undergo premarital screening for thalassemia and 71.2% of the couples were not notified of their own minor thalassemia until a child was born with major thalassemia. Of the diagnosed minor couples, about 25% did PND and the others did not carry out because mothers were unaware of proper gestational age and of the importance of this issue, financial problems, and the husbands' disagreement to take the tests. Moreover, 16 mothers, in spite of being diagnosed of having a major fetus, refused to terminate the pregnancy.

CONCLUSION

The most preventable causes for affected births include couples' unawareness of being minor and unawares of the PND importance and process.

Identification and genetic variation of fasciola species from tabriz, north- Western iran

BACKGROUND

Fascioliasis is considered as the most important helminthic infection of cattle and sheep. Traditional approaches using morphological and biologic characters cannot cause a certainty in the accurate and precise identification and intra-specific differences of Fasciola spp. In this study, we identified Fasciola species using ITS-1 marker and described genetic variation of each species of the parasite in isolates from Tabriz slaughterhouse in West Azerbaijan Province, north- western Iran.

METHODS

Overall, 100 samples (50 from sheep and 50 from cattle) morphologically detected as Fasciola worms were studied for identification of Fasciola species by PCR-RFLP method and intra-species variation of the parasite using RAPD-PCR technique.

RESULTS

A region of approximately 460bp in all samples was successfully amplified. There were no identifiable variations among the size of PCR products. Two and three fragments in samples correspond to F. hepatica and F. gigantica was seen, respectively, through PCR-RFLP method. No difference was seen in digestion pattern according to host (sheep or cattle). Different types of each species of the parasite was observed using RAPD-PCR technique.

CONCLUSION

We could have an estimate of frequency of F. hepatica and F. gigantic and different genotypes of the parasite in isolates from one locality in north- western of Iran. By extension of such studies in future to other animal hosts (buffalo and goat) and including more regions to sampling, the reliability of the results and their application for control programs in zoonotic diseases will be increased.

Comparison of naproxen with placebo for the management of noncyclical breast pain: a randomized, double-blind, controlled trial

BACKGROUND

Breast pain is a common symptom in patients attending breast clinics. Although most patients experience mastalgia of mild to moderate severity, approximately 15% of patients suffer from severe pain that causes significant distress and some disturbance in their daily life that lead them to seek treatment. Despite a considerable number of drugs suggested for decreasing the severity of mastalgia, there is no standard treatment for the complaint. In this study, we investigated the effect of naproxen on reducing the complaint of breast pain compared with placebo.

METHODS

Eighty-one women suffering from noncyclic breast pain were recruited to a randomized, double-blind, clinical trial between January 2002 and September 2004. All patients were suffering from this complaint for at least 3 months before the study. Patients were randomly assigned to two groups. Patients in the case group received naproxen 250 mg BD. Patients in the placebo group took placebo in a similar manner. The intensity of mastalgia was assessed before and twice after intervention by using a Visual Analogue Scale.

RESULTS

Forty-two of 81 patients were recruited randomly as cases and the remaining 39 were assigned placebo. Of these 24 and 22 patients fulfilled the study protocol respectively. The mean age of patients was 35 (SD = 7.5; range, 19-55) years. The mean pain severity at the beginning of the study was 5.8 and 6.1 in naproxen and placebo groups, respectively. The severity of pain was decreased significantly at the end of the study in both groups (3.9 in patients and 3.7 in controls (P = 0.005 and 0.0001)). Although the decrease in pain severity in each individual group was statistically significant, it was not significant compared with one another (P = 0.64).

CONCLUSIONS

Breast pain is a complex symptom that can be relieved significantly with reassurance. According to the result of this study, naproxen has no superiority over placebo in reducing noncyclic breast pain.

Use of Frost sutures in an orbital trauma patient with extensive conjunctival oedema and pseudoproptosis

Frost sutures are temporary suspension sutures conventionally used in oculoplastics. The case is presented here of a patient with multiple orbital fractures who developed worsening conjunctival chemosis and pseudoproptosis. This patient was managed successfully with Frost sutures. To the best of the authors' knowledge, there is no documented use of Frost sutures in this type of case. It is emphasized that this technique should only be considered following rigorous exclusion of retrobulbar pathology and careful attention towards early detection of raised intraocular pressure.

Study of the effect of renal transplantation on methacholine challenge test in patients with end-stage renal failure in Shahid Doctor Labafinejad Hospital in Tehran, Iran

Pulmonary complications are common in patients with chronic renal failure (CRF). The objective of this study was determine the effect of renal transplantation on pulmonary function, using a methacholine challenge test. This interventional study included 14 CRF patients on maintenance dialysis who underwent serial spirometry and astography before and after renal transplantation. None of them was known to have clinically important pulmonary or heart disease. The results of spirometry, astography, echocardiography, and chest X-ray were normal. Five patients were men and all others were women. The overall age range was 15 to 45 years (mean age = 28.6 +/- 10.9). For every patient four times astography was done. The mean values of spirometric and astography indices before and after renal transplantation were within normal limit. But by repeated measure analysis of variance, the results actually showed improved airway responsiveness (although within normal limits). The most common pathological lung condition in CRF is pulmonary edema, usually due to a combination of fluid overload and abnormal permeability of the pulmonary microcirculation. However, our patients had no symptomatic pulmonary edema, but minor degrees of fluid retention are virtually impossible to detect clinically and could not be excluded. Therefore, it seems that disappearance of subclinical pulmonary edema was the likeliest cause of an increase in minimum dose of methacholine, and therefore improvement in airway responsiveness after renal transplantation.

Bilateral posterior dislocation of the crystalline lens after a head injury sustained during a seizure

This article presents a case of bilateral posterior dislocations of the crystalline lens in a patient with epilepsy who presented with reduced vision and anisocoria 2 weeks after having sustained head injuries during a seizure. The possibility of lens dislocation was raised only at this time, and subsequently confirmed on computed tomography. Such patients may require prompt referral to the ophthalmologist to treat complications such as functional aphakia, uveitis and more seriously pupillary block glaucoma. This case highlights the importance of ocular examination of head injuries to rule out possible ophthalmological pathology.

Age-related changes in the thickness of the human lamina cribrosa

OBJECTIVE

To measure the human lamina cribrosa thickness (LCT) in vitro in fully hydrated specimens and to determine whether there is any association between thickness and age or sex.

METHODS

45 fixed human optic nerves, age range 9-90 years, were dissected from the globe and frozen sectioned. The study was divided into two parts: the first investigated the overall change in LCT and cribrosal beam thickness (CBT) with age, and the second divided eyes into two specific age groups (38-49 and 78-87 years) and assessed differences with respect to age and sex.

RESULTS

LCT ranged from 345.4 to 555.9 microm between the samples. A positive relationship was found between LCT and age (LCT = 2.41xage+365.5, 95% confidence interval (CI) for slope 1.31 to 3.52; r(2) = 0.30, p<0.001). A regional difference in CBT was observed, with beams being thickest at the posterior cribrosa (mean 14.8 (standard deviation (SD) 2.2) microm) and thinnest at the anterior cribrosa (9.8 (SD 2.4) microm). CBT increased with increasing age. Differences related to sex were also found, with females having relatively thinner LCT than males, irrespective of age, but this was not statistically significant.

CONCLUSIONS

This study shows an increase in human LCT with increasing age. This changing structural property of the lamina cribrosa may have implications for its functioning with respect to compliance and reversibility, and has particular relevance to glaucoma, where increasing age has been identified as a strong risk factor for the development of the disease.

An evaluation of gender, body mass index, wrist circumference and wrist ratio as independent risk factors for carpal tunnel syndrome

OBJECTIVES

The aim of this study was to evaluate the role of gender, body mass index (BMI), wrist ratio (WR) and wrist circumference as independent risk factors for carpal tunnel syndrome (CTS) and to analyze the strength of association of these factors.

METHODS

We have undertaken a case-control study in 128 CTS patients and 109 controls. Based on clinical and electrophysiologic criteria, 109 female and 19 male CTS patients as well as 62 female and 47 male control subjects were selected from patients and their relatives referred to our hospital. In total, 179 hands with CTS in three groups of severity (mild, moderate and severe) were examined. Height, weight, BMI, wrist width, depth, circumference and ratio were measured in all patients and control group. Mean values of different risk factors for CTS group and controls were measured. A logistic regression analysis was conducted to evaluate odds ratio of different risk factors.

RESULTS

The mean values for BMI and WR were greater in CTS patients than in the subject group. Thirty-four, 89 and 57 patients had mild, moderate and severe CTS, respectively. Mean age, BMI, wrist circumference and ratio were not statistically significant in the three groups. Female gender, increased BMI and increased WR had odds ratio of 9.95, 1.75 and 1.12, respectively.

CONCLUSION

Our study confirms that female gender, obesity and square wrists are independent risk factors for CTS.