Structure of Designer Antibody-like Peptides Binding to the Human C5a with Potential to Modulate the C5a Receptor Signaling.

C5a is an integral glycoprotein of the complement system that plays an important role in inflammation and immunity. The physiological concentration of C5a is observed to be elevated under various immunoinflammatory pathophysiological conditions in humans. The pathophysiology of C5a is linked to the "two-site" protein-protein interactions (PPIs) with two genomically related receptors, such as C5aR1 and C5aR2. Therefore, pharmacophores that can potentially block the PPIs between C5a-C5aR1 and C5a-C5aR2 have tremendous potential for development as future therapeutics. Notably, the FDA has already approved antibodies that target the precursors of C5a (Eculizumab, 148 kDa) and C5a (Vilobelimab, 149 kDa) for marketing as complement-targeted therapeutics. In this context, the current study reports the structural characterization of a pair of synthetic designer antibody-like peptides (DePA and DePA1; ≤3.8 kDa) that bind to hotspot regions on C5a and also demonstrates potential traits to neutralize the function of C5a under pathophysiological conditions.

A Rationally Designed Synthetic Antiviral Peptide Binder Targeting the Receptor-Binding Domain of SARS-CoV-2.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), a novel coronavirus, is the causative agent responsible for the spread of the COVID19 pandemic across the globe. The global impact of the COVID19 pandemic, the successful approval of vaccines for controlling the pandemic, and the further resurgence of COVID19 necessitate the exploration and validation of alternative therapeutic avenues targeting SARS-CoV-2. The initial entry and further invasion by SARS-CoV-2 require strong protein-protein interactions (PPIs) between the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein and the human angiotensin-converting enzyme 2 (ACE2) receptors expressed on the cell surfaces of various tissues. In principle, disruption of the PPIs between the RBD of SARS-CoV-2 and the ACE2 receptor by designer peptides with optimized pharmacology appears to be an ideal choice for potentially preventing viral entry with minimal immunogenicity. In this context, the current study describes a short, synthetic designer peptide (codenamed SR16, ≤18 aa, molecular weight ≤2.5 kDa), which has a few noncoded amino acids, demonstrates a helical conformation in solution, and also engages the RBD of SARS-CoV-2 through a high-affinity interaction, as judged from a battery of biophysical studies. Further, the designer peptide demonstrates resistance to trypsin degradation, appears to be nontoxic to mammalian cells, and also does not induce hemolysis in freshly isolated human erythrocytes. In summary, SR16 appears to be an ideal peptide binder targeting the RBD of SARS-CoV-2, which has the potential for further optimization and development as an antiviral agent targeting SARS-CoV-2.

Laryngeal Anaplastic Lymphoma Kinase-Positive B-cell Lymphoma: Case Report and Review.

Larynx is an uncommon extranodal site for non-Hodgkin lymphoma (NHL). Anaplastic lymphoma kinase (ALK)-positive B-cell lymphoma is a rare and aggressive form of NHL. A 19-year-old male presented to the ENT department with globus sensation, hoarseness, cervical lymphadenopathy and weight loss. A 70-degree rigid endoscopic examination of the larynx showed a vascular, irregular, submucosal mass arising from the right aryepiglottic fold causing near complete obstruction of the laryngeal airway. PET-CT showed hypermetabolic lesions in the supraglottis, cervical lymph nodes, cervical spine, ribs and abdominal lymph nodes. Biopsy was taken from the supraglottic mass as well as the enlarged cervical lymph nodes, which revealed ALK-positive large B-cell NHL. In this report, we present a rare case of ALK-positive large B-cell NHL of the larynx, discussing its clinical, radiological and pathological features. A limited review of literature is also presented. There is a need to develop a database for the description of lymphomas affecting the larynx and this case report adds to the existing knowledge of this rare entity.

Mitochondrial metabolic determinants of multiple myeloma growth, survival, and therapy efficacy.

Multiple myeloma (MM) is a plasma cell dyscrasia characterized by the clonal proliferation of antibody producing plasma cells. Despite the use of next generation proteasome inhibitors (PI), immunomodulatory agents (IMiDs) and immunotherapy, the development of therapy refractory disease is common, with approximately 20% of MM patients succumbing to aggressive treatment-refractory disease within 2 years of diagnosis. A large emphasis is placed on understanding inter/intra-tumoral genetic, epigenetic and transcriptomic changes contributing to relapsed/refractory disease, however, the contribution of cellular metabolism and intrinsic/extrinsic metabolites to therapy sensitivity and resistance mechanisms is less well understood. Cancer cells depend on specific metabolites for bioenergetics, duplication of biomass and redox homeostasis for growth, proliferation, and survival. Cancer therapy, importantly, largely relies on targeting cellular growth, proliferation, and survival. Thus, understanding the metabolic changes intersecting with a drug's mechanism of action can inform us of methods to elicit deeper responses and prevent acquired resistance. Knowledge of the Warburg effect and elevated aerobic glycolysis in cancer cells, including MM, has allowed us to capitalize on this phenomenon for diagnostics and prognostics. The demonstration that mitochondria play critical roles in cancer development, progression, and therapy sensitivity despite the inherent preference of cancer cells to engage aerobic glycolysis has re-invigorated deeper inquiry into how mitochondrial metabolism regulates tumor biology and therapy efficacy. Mitochondria are the sole source for coupled respiration mediated ATP synthesis and a key source for the anabolic synthesis of amino acids and reducing equivalents. Beyond their core metabolic activities, mitochondria facilitate apoptotic cell death, impact the activation of the cytosolic integrated response to stress, and through nuclear and cytosolic retrograde crosstalk maintain cell fitness and survival. Here, we hope to shed light on key mitochondrial functions that shape MM development and therapy sensitivity.

Therapeutic implications of mitochondrial stress-induced proteasome inhibitor resistance in multiple myeloma.

The connections between metabolic state and therapy resistance in multiple myeloma (MM) are poorly understood. We previously reported that electron transport chain (ETC) suppression promotes sensitivity to the BCL-2 antagonist venetoclax. Here, we show that ETC suppression promotes resistance to proteasome inhibitors (PIs). Interrogation of ETC-suppressed MM reveals integrated stress response-dependent suppression of protein translation and ubiquitination, leading to PI resistance. ETC and protein translation gene expression signatures from the CoMMpass trial are down-regulated in patients with poor outcome and relapse, corroborating our in vitro findings. ETC-suppressed MM exhibits up-regulation of the cystine-glutamate antiporter SLC7A11, and analysis of patient single-cell RNA-seq shows that clusters with low ETC gene expression correlate with higher SLC7A11 expression. Furthermore, erastin or venetoclax treatment diminishes mitochondrial stress-induced PI resistance. In sum, our work demonstrates that mitochondrial stress promotes PI resistance and underscores the need for implementing combinatorial regimens in MM cognizant of mitochondrial metabolic state.

Modified Inguinal Lymph Node Dissection in Groin-Negative Patients of Penile Cancer: Our Experience.

Cancer of the penis is an important health problem in India, causing significant morbidity. Involvement of locoregional lymph nodes is the most significant prognostic factor for patients with penile cancer. In this study, we reviewed clinical data of all patients who underwent modified inguinal lymph node dissection as a means to diagnose micro-metastasis in inguinal lymph nodes, and analysed the outcomes. We retrospectively reviewed the hospital clinical charts of patients treated for carcinoma of the penis. Inguinal and distant metastases were assessed by physical examination, ultrasound imaging of the inguinal region, computed tomography of the abdomen and pelvis and a chest radiograph. Patients with clinically negative inguinal lymph nodes underwent modified lymph node dissection (mILND) both to diagnose and stage the disease. Complications occurring during a 30-day period after surgery were defined as early and thereafter as late complications. A total of 40 patients with a mean age of 52.27±13.10 (range 25-73) years underwent mILND. Wedge biopsy from the primary lesion had revealed intermediate-risk disease in 22 (55%) patients and high-risk disease in 18 (45%) patients. Histopathological examination of the primary penile lesion revealed a pT1 lesion in 32 patients and a pT2 lesion in the remaining 8 patients. Fourteen (35%) of the 40 patients showed micro-metastases in the inguinal lymph nodes on frozen sections. The mean follow-up in these patients was 56.6±18.09 months. There were no instances of local or systemic recurrences seen in 38 (95%) patients within 5 years. Superficial lymph node dissection and where facilities are available DSLNB remain the standard of care in the management of patients with clinically groin-negative (cN0) intermediate- and high-risk groups. Modified inguinal lymph node dissection would be a safe and appropriate alternative to this in all centres that do not have access to newer modalities like DSLNB, video-endoscopic (VEIL) or robotic-assisted techniques.

Therapeutic ureteroscopy for urolithiasis in children younger than 60 months of age.

PURPOSE: The management of urinary tract calculi has evolved dramatically in children with the development of smaller and more durable endoscopic equipment. The indications for therapeutic ureteroscopy in children have significantly expanded with the availability of smaller caliber endoscopes and Holmium:YAG laser. In this paper, we review our experience of the management of urolithiasis and report outcomes of therapeutic ureterorenoscopy (URS) in children younger than 60 months. METHODS: We retrospectively reviewed the inpatient, outpatient records, and imaging data of our hospital, of all children ≤ 60 months of age undergoing URS for the treatment of urinary stones. RESULTS: During the study period; 77 children, mostly male (70.1%) presenting with a single calculus and a mean age of 28.97 ± 2.44 months underwent therapeutic URS. A majority of children (71.4%) had lower or mid-ureteric calculi. Pre URS double J (DJ) stenting was necessary for 21 (27.2%) children. A total of 24 (31.1%) children needed ureteric dilatation before the ureteroscopy. Post URS DJ stenting was necessary in 41 (53.2%) children. Stents were retrieved within 10 days of the procedure. Stone clearance rate following a single-stage URS procedure was 94.8%, and 4 (5.2%) children needed additional shockwave lithotripsy (SWL) to achieve stone clearance. Overall complication rate including hematuria and fever was 12.9% (10 patients). CONCLUSION: Therapeutic ureterorenoscopy in the management of ureteric and selective renal pelvic calculi is safe and effective. It can be considered as the first-line therapy in young children.

Nascent peptide assists the ribosome in recognizing chemically distinct small molecules.

Regulation of gene expression in response to the changing environment is critical for cell survival. For instance, binding of macrolide antibiotics to the ribosome promotes translation arrest at the leader open reading frames ermCL and ermBL, which is necessary for inducing the antibiotic resistance genes ermC and ermB. Cladinose-containing macrolides such as erythromycin (ERY), but not ketolides such as telithromycin (TEL), arrest translation of ermCL, whereas either ERY or TEL stall ermBL translation. How the ribosome distinguishes between chemically similar small molecules is unknown. We show that single amino acid changes in the leader peptide switch the specificity of recognition of distinct molecules, triggering gene activation in response to ERY alone, to TEL alone or to both antibiotics or preventing stalling altogether. Thus, the ribosomal response to chemical signals can be modulated by minute changes in the nascent peptide, suggesting that protein sequences could have been optimized for rendering translation sensitive to environmental cues.

Propranolol therapy in a case of capillary hemangioma.

Capillary hemangioma is one the most common tumors of eyelid and orbit reported in pediatric age group. Oral propranolol therapy is latest addition to the armamentarium of treatment options available to ophthalmologists in treating capillary hemangiomas. We report the successful response to propranolol therapy to a 5-year-old child with capillary hemangioma involving lids, orbit, and the paranasal sinuses. A long-term follow-up is necessary for the prognostic efficacy of the therapy.

Molecular basis for erythromycin-dependent ribosome stalling during translation of the ErmBL leader peptide.

In bacteria, ribosome stalling during translation of ErmBL leader peptide occurs in the presence of the antibiotic erythromycin and leads to induction of expression of the downstream macrolide resistance methyltransferase ErmB. The lack of structures of drug-dependent stalled ribosome complexes (SRCs) has limited our mechanistic understanding of this regulatory process. Here we present a cryo-electron microscopy structure of the erythromycin-dependent ErmBL-SRC. The structure reveals that the antibiotic does not interact directly with ErmBL, but rather redirects the path of the peptide within the tunnel. Furthermore, we identify a key peptide-ribosome interaction that defines an important relay pathway from the ribosomal tunnel to the peptidyltransferase centre (PTC). The PTC of the ErmBL-SRC appears to adopt an uninduced state that prevents accommodation of Lys-tRNA at the A-site, thus providing structural basis for understanding how the drug and the nascent peptide cooperate to inhibit peptide bond formation and induce translation arrest.

Regulation of gene expression by macrolide-induced ribosomal frameshifting.

The expression of many genes is controlled by upstream ORFs (uORFs). Typically, the progression of the ribosome through a regulatory uORF, which depends on the physiological state of the cell, influences the expression of the downstream gene. In the classic mechanism of induction of macrolide resistance genes, antibiotics promote translation arrest within the uORF, and the static ribosome induces a conformational change in mRNA, resulting in the activation of translation of the resistance cistron. We show that ketolide antibiotics, which do not induce ribosome stalling at the uORF of the ermC resistance gene, trigger its expression via a unique mechanism. Ketolides promote frameshifting at the uORF, allowing the translating ribosome to invade the intergenic spacer. The dynamic unfolding of the mRNA structure leads to the activation of resistance. Conceptually similar mechanisms may control other cellular genes. The identified property of ketolides to reduce the fidelity of reading frame maintenance may have medical implications.

Deregulation of translation due to post-transcriptional modification of rRNA explains why erm genes are inducible.

A key mechanism of bacterial resistance to macrolide antibiotics is the dimethylation of a nucleotide in the large ribosomal subunit by erythromycin resistance methyltransferases. The majority of erm genes are expressed only when the antibiotic is present and the erythromycin resistance methyltransferase activity is critical for the survival of bacteria. Although these genes were among the first discovered inducible resistance genes, the molecular basis for their inducibility has remained unknown. Here we show that erythromycin resistance methyltransferase expression reduces cell fitness. Modification of the nucleotide in the ribosomal tunnel skews the cellular proteome by deregulating the expression of a set of proteins. We further demonstrate that aberrant translation of specific proteins results from abnormal interactions of the nascent peptide with the erythromycin resistance methyltransferase-modified ribosomal tunnel. Our findings provide a plausible explanation why erm genes have evolved to be inducible and underscore the importance of nascent peptide recognition by the ribosome for generating a balanced cellular proteome.