Glycosylation shapes the efficacy and safety of diverse protein, gene and cell therapies

Over recent decades, therapeutic proteins have had widespread success in treating a myriad of diseases. Glycosylation, a near universal feature of this class of drugs, is a critical quality attribute that significantly influences the physical properties, safety profile and biological activity of therapeutic proteins. Optimizing protein glycosylation, therefore, offers an important avenue to developing more efficacious therapies. In this review, we discuss specific examples of how variations in glycan structure and glycoengineering impacts the stability, safety, and clinical efficacy of protein-based drugs that are already in the market as well as those that are still in preclinical development. We also highlight the impact of glycosylation on next generation biologics such as T cell-based cancer therapy and gene therapy.

Fatty acids negatively regulate platelet function through formation of noncanonical 15-lipoxygenase-derived eicosanoids

The antiplatelet effect of polyunsaturated fatty acids is primarily attributed to its metabolism to bioactive metabolites by oxygenases, such as lipoxygenases (LOX). Platelets have demonstrated the ability to generate 15-LOX-derived metabolites (15-oxylipins); however, whether 15-LOX is in the platelet or is required for the formation of 15-oxylipins remains unclear. This study seeks to elucidate whether 15-LOX is required for the formation of 15-oxylipins in the platelet and determine their mechanistic effects on platelet reactivity. In this study, 15-HETrE, 15-HETE, and 15-HEPE attenuated collagen-induced platelet aggregation, and 15-HETrE inhibited platelet aggregation induced by different agonists. The observed anti-aggregatory effect was due to the inhibition of intracellular signaling including αIIbβ3 and protein kinase C activities, calcium mobilization, and granule secretion. While 15-HETrE inhibited platelets partially through activation of peroxisome proliferator-activated receptor β (PPARβ), 15-HETE also inhibited platelets partially through activation of PPARα. 15-HETrE, 15-HETE, or 15-HEPE inhibited 12-LOX in vitro, with arachidonic acid as the substrate. Additionally, a 15-oxylipin-dependent attenuation of 12-HETE level was observed in platelets following ex vivo treatment with 15-HETrE, 15-HETE, or 15-HEPE. Platelets treated with DGLA formed 15-HETrE and collagen-induced platelet aggregation was attenuated only in the presence of ML355 or aspirin, but not in the presence of 15-LOX-1 or 15-LOX-2 inhibitors. Expression of 15-LOX-1, but not 15-LOX-2, was decreased in leukocyte-depleted platelets compared to non-depleted platelets. Taken together, these findings suggest that 15-oxylipins regulate platelet reactivity; however, platelet expression of 15-LOX-1 is low, suggesting that 15-oxylipins may be formed in the platelet through a 15-LOX-independent pathway.

Structural basis for altered positional specificity of 15-lipoxygenase-1 with 5S-HETE and 7S-HDHA and the implications for the biosynthesis of resolvin E4

Human 15-lipoxygenases (LOX) are critical enzymes in the inflammatory process, producing various pro-resolution molecules, such as lipoxins and resolvins, but the exact role each of the two 15-LOXs in these biosynthetic pathways remains elusive. Previously, it was observed that h15-LOX-1 reacted with 5S-HETE in a non-canonical manner, producing primarily the 5S,12S-diHETE product. To determine the active site constraints of h15-LOX-1 in achieving this reactivity, amino acids involved in the fatty acid binding were investigated. It was observed that R402L did not have a large effect on 5S-HETE catalysis, but F414 appeared to π-π stack with 5S-HETE, as seen with AA binding, indicating an aromatic interaction between a double bond of 5S-HETE and F414. Decreasing the size of F352 and I417 shifted oxygenation of 5S-HETE to C12, while increasing the size of these residues reversed the positional specificity of 5S-HETE to C15. Mutants at these locations demonstrated a similar effect with 7S-HDHA as the substrate, indicating that the depth of the active site regulates product specificity for both substrates. Together, these data indicate that of the three regions proposed to control positional specificity, π-π stacking and active site cavity depth are the primary determinants of positional specificity with 5S-HETE and h15-LOX-1. Finally, the altered reactivity of h15-LOX-1 was also observed with 5S-HEPE, producing 5S,12S-diHEPE instead of 5S,15S-diHEPE (aka resolvin E₄ (RvE₄). However, h15-LOX-2 efficiently produces 5S,15S-diHEPE from 5S-HEPE. This result is important with respect to the biosynthesis of the RvE₄ since it obscures which LOX isozyme is involved in its biosynthesis. Future work detailing the expression levels of the lipoxygenase isoforms in immune cells and selective inhibition during the inflammatory response will be required for a comprehensive understanding of RvE₄ biosynthesis.

[Assessment of quality of life after antireflux surgery]

AIM OF THE STUDY

To assess the quality of life (QoL) of patients operated for gastroesophageal reflux disease (GERD).

PATIENTS AND METHODS

This prospective study included 82 consecutive patients submitted to antireflux surgery between October 1998 and January 1999. A new questionnaire was used to assess their QoL: the Gastrointestinal Quality of Life Index (GIQLI) that includes 36 items concerning 5 dimensions: symptoms, vitality, emotions, social relations and medical treatment. The series consisted of 44 men and 38 women with a mean age of 47 years (range: 18-78). QoL was assessed before and 6 months after surgery; the follow-up rate was 94% (77/82). The pre- and postoperative GIQLI scores of the study group and the GIQLY score of a control group of 110 healthy patients were compared.

RESULTS

Before surgery, the GIQLI score (90 +/- 23) was greatly impaired compared to the score (123 +/- 13) observed in the control group (p < 0.001). After surgery, the GIQLI score (110 +/- 23) increased significantly (p < 0.001), but remained statistically lower than the score of the control group (p < 0.001). The postoperative score recorded in the symptoms dimension was lower than the control group score: 55 +/- 11 versus 66 +/- 6 (p < 0.001), while no significant difference was observed in the other 4 dimensions. Univariate statistical analysis revealed that the postoperative GIQLI score (y) was correlated with the preoperative GIQLI score (x) according to the formula: y = 0.43 x + 71 (p < 0.001) and the sex of the patients, as the postoperative GIQLI score was higher in male patients (115 +/- 19) than in female patients (103 +/- 23) (p < 0.02).

CONCLUSION

The QoL of the patients was greatly improved after antireflux surgery, but remained lower than that of a control group of healthy subjects. Better patient selection should improve the results. In our series, male patients or patients with a high preoperative GIQLI score were the best candidates for antireflux surgery.

A multicentric comparison of transabdominal versus totally extraperitoneal laparoscopic hernia repair using PARIETEX meshes

The authors report a series of 1972 inguinal hernias treated between 1993 and 1997 by the insertion of a PARIETEX mesh via either a transabdominal-preperitoneal (TAPP) (1,290 procedures) or a totally extraperitoneal TEP approach (682 procedures). Pain scores were equivalent in both groups, while the hospital stay and time to return to normal activity was lower in the TEP group than in the TAPP group (p<0.001). In both groups, the average incidence of the total reported events (complications) was around 10% with no statistical difference. This ratio seemed to compare favorably to previously published reports. Chronic pain was extremely rare (0.6% and 0.7% in the TAPP and TEP groups, respectively). Whatever the approach was, sepsis was also very rare (1/1,526 laparoscopic procedures). These findings illustrate the local tolerance of the mesh. Recurrence rates were below 1% with no statistical difference between groups. This retrospective study demonstrates the clinically apparent local tolerance of this type of mesh. Prospective and long-term clinical results will be necessary to demonstrate that the optimized short-term tolerance of PARIETEX mesh will influence the long term functional results.

[Time off of work after inguinal hernia repair. Results of a multicenter prospective study]

A multicentre prospective study was conducted to evaluate the effective duration of time off work following inguinal hernia repair. From 1st October to 30 November 1997, 14 surgeons repaired 459 hernias in 359 patients, corresponding to 28.8% of salaried workers, 10.9% self-employed and 4.8% civil servants. 46% of patients were retired. Only 6.9% of patients were treated by reconstruction of the inguinal floor without mesh, 59.6% were operated by laparoscopy and a conventional prosthesis repair was performed in 33.2%. There were 0.6% of complications or modifications of the postoperative course. The mean effective time off work was 17.5 days after unilateral repair and 24.7 days after bilateral repair. For unilateral repairs, no significant difference was observed between occupational groups in terms of effective time off work, in the absence of complications. In contrast, patients of these occupational groups presented a shorter time off work following an uncomplicated TAPP repair than after plug-Lichtenstein repair. In the group of salaried workers, a significant difference was observed between patients undergoing TAPP or TEP repair and those undergoing plug-Lichtenstein repair.

Breakdowns on the path of chronic illness: opportunities for learning

An unusual case of calciphylaxis, presenting at the onset of end-stage renal disease and evolving into an extended and arduous hospital stay, is described. The medical approach to this case is addressed briefly, but the main focus of this paper is to describe, in the words of various participants, the events and interactions that occurred and to learn from this description how our management of such cases breaks down. When confronted by difficult circumstances, it is common for us to react emotionally in ways that are automatic and based on our own personal histories and behavior patterns. Such automatic reactions prevent us from seeing and understanding what we really need to know about a given situation and leave us vulnerable to discouragement and internal suffering when clinical events do not go well (A. Nierenberg, personal communication, April 1998). The result is often exasperation with patients and families, as well as emotionally laden interactions that do not forward problem solving. In retrospect, the appearance of such breakdowns is not only predictable in the course of chronic illness, but offers us the opportunity to observe our automatic reactions, to re-evaluate our approach, and to redesign our actions. We have written this review, not to find error or blame, but rather to emphasize that we are learning to view these breakdowns as signals first to step back from our automatic reactions and then to listen and communicate clearly as a means to navigating the best pathway through difficult and discouraging clinical challenges.

Mother as shield: differential effects of contact and nursing on pain responsivity in infant rats--evidence for nonopioid mediation

To determine how rat mothers protect their pups against pain, we applied focal heat (34-51 degrees C) to the ear or shoulder of 10-day-old rats that were isolated, in contact among themselves or with their mother, suckling nonnutritively, or in the hyperextension position normally caused by milk letdown. Relative to isolated rats, contact doubled withdrawal latencies from heat (43 or 45 degrees C) applied to the ear. Suckling quadrupled heat-escape latencies. During hyperextension, rats essentially did not escape from thermal stimulation of up to 48 degrees C. Protection provided by maternal contact, especially suckling, was not mediated by either mu or kappa opioid receptors: neither systemic injections of naltrexone nor norbinaltorphimine reduced heat-escape latencies. Morphine (0.125 and 0.250 mg/kg) added to the effects of contact but multiplied the effects of suckling to produce heat-escape latencies that were upward of 2 min.

Mother as shield: differential effects of contact and nursing on pain responsivity in infant rats--evidence for nonopioid mediation

To determine how rat mothers protect their pups against pain, we applied focal heat (34-51 degrees C) to the ear or shoulder of 10-day-old rats that were isolated, in contact among themselves or with their mother, suckling nonnutritively, or in the hyperextension position normally caused by milk letdown. Relative to isolated rats, contact doubled withdrawal latencies from heat (43 or 45 degrees C) applied to the ear. Suckling quadrupled heat-escape latencies. During hyperextension, rats essentially did not escape from thermal stimulation of up to 48 degrees C. Protection provided by maternal contact, especially suckling, was not mediated by either mu or kappa opioid receptors: neither systemic injections of naltrexone nor norbinaltorphimine reduced heat-escape latencies. Morphine (0.125 and 0.250 mg/kg) added to the effects of contact but multiplied the effects of suckling to produce heat-escape latencies that were upward of 2 min.

Complete disappearance of a leiomyosarcoma of the lower extremity following preoperative hyperthermia and intra-arterial doxorubicin

Leiomyosarcoma of the extremities is an unusual tumor. Herein we report a unique and what we believe is the first case of a patient in whom there was complete disappearance of such a tumor following regional hyperthermia and chemotherapy.

Perspectives in colorectal cancer

This paper presents an overview of recent developments pertaining to colorectal adenocarcinoma. It is aimed toward the practicing clinician. Topics discussed include epidemiologic observations; genetic predispositions; molecular biology findings; screening and early detection programs; endoscopy; principles of surgical resection; laser and radioimmunoguided surgery; staging; selection of patients for adjuvant chemotherapy; and considerations regarding biologic response modifiers and pain control in the advanced-disease setting.

Kinins are generated during experimental rhinovirus colds

We investigated the pathophysiology of rhinovirus colds by challenging volunteers with either of two strains of rhinovirus or with placebo. Nasal lavages were done before challenge and every 4 h for five days after challenge. We measured the levels of histamine, kinins, [3H]-N-alpha-p-tosyl-L-arginine methyl ester (TAME)-esterase activity, and albumin and counted the number of neutrophils in the recovered lavage fluid. Subjects who became both infected and symptomatic showed increases in levels of kinins (P less than .03), TAME-esterase activity (P less than .04), and albumin (P less than .05), as well as in the number of neutrophils (P less than .01). The total number of symptoms reported correlated significantly with the net increase in the concentration of kinins (r = .549; P less than .01), albumin (r = .674; P less than .001), TAME-esterase activity (r = .563; P less than .005), and neutrophils (r = .605; P less than .005). Levels of histamine did not change during the course of infection. During symptomatic rhinovirus infections (1) kinins are generated, (2) vascular permeability increases, (3) basophils and mast cells do not participate, and (4) neutrophils enter nasal secretions.

The structure and nucleotide sequence of the 5' end of the human c-myc oncogene

We have established the structure and nucleotide sequence of the 5' end of the human c-myc oncogene, using a cloned genomic fragment isolated from a fetal liver library (clone lambda MC41) and cloned cDNA from the human leukemic cell line K562. The human c-myc oncogene consists of three exons and two introns. Primer extension of the human c-myc mRNA of three different cell lines and S1 nuclease protection experiments served to establish the position of two transcription initiation sites. The splicing site of the first exon-intron boundary was determined by comparative analysis of the sequences of the genomic and cDNA clones. The first exon contains termination codons in all three reading frames and no translation initiation signals, confirming our previous observation that the c-myc mRNA has a long 5' noncoding sequence. This first exon also was found to be utilized in the formation of c-myc mRNAs in a variety of human cell lines.

Subcellular structures involved in internalization and degradation of epidermal growth factor

Epidermal Growth Factor (EGF), a small polypeptide which acts as a mitogen for many cell types, has previously been shown to bind to a specific plasma membrane receptor on 3T3 cells. If 125I-EGF is bound to 3T3 cells for one hour at 4 degrees C, it remains predominantly associated with the plasma membrane-containing fractions obtained by subjecting cell supernatants to equilibrium sedimentation on sucrose gradients. When binding is followed by a 10-minute incubation at 37 degrees C, over 50% of the 125I-EGF is associated with two internal membrane-containing peaks having higher densities than the plasma membrane. After one hour at 37 degrees C, over 80% of the 125I-EGF is degraded and removed from the cells. The most rapidly labeled internal peak corresponds in density to brain-coated vesicles (CVs). Antiserum prepared against coated vesicles from brain precipitates the 125I-EGF in this peak. In addition, CVs containing 125I-EGF can be co-purified from 3T3 cells exposed to 125I-EGF, using brain as a carrier. Several lines of evidence suggest that the other 125I-EGF-labeled intracellular peak is 125I-EGF in lysosomes. These results provide kinetic and biochemical evidence for a unidirectional pathway for EGF catabolism by 3T3 cells. EGF first binds to the plasma membrane bound receptors, is then moved to the cytoplasm in CVs, and finally appears in lysosomes, where it is degraded and released from the cells. Ten-millimolar NH4Cl blocks lysosomal hydrolysis of EGF almost completely. Subsequently, EGF internalization is inhibited. This finding suggests that the pathway for EGF internalization and degradation is tightly coupled.