Structural insights into IL-11-mediated signalling and human IL6ST variant-associated immunodeficiency.

IL-11 and IL-6 activate signalling via assembly of the cell surface receptor gp130; however, it is unclear how signals are transmitted across the membrane to instruct cellular responses. Here we solve the cryoEM structure of the IL-11 receptor recognition complex to discover how differences in gp130-binding interfaces may drive signalling outcomes. We explore how mutations in the IL6ST gene encoding for gp130, which cause severe immune deficiencies in humans, impair signalling without blocking cytokine binding. We use cryoEM to solve structures of both IL-11 and IL-6 complexes with a mutant form of gp130 associated with human disease. Together with molecular dynamics simulations, we show that the disease-associated variant led to an increase in flexibility including motion within the cytokine-binding core and increased distance between extracellular domains. However, these distances are minimized as the transmembrane helix exits the membrane, suggesting a stringency in geometry for signalling and dimmer switch mode of action.

Cerebral filariasis infection with Litomosoides in Molossus barnesi (Chiroptera: Molossidae) in the Brazilian eastern Amazon, with comments on Molossinema wimsatti Georgi, Georgi, Jiang and Fronguillo, 1987.

During bacterial and viral pathogen investigation of 30 specimens of bats captured in periurban forest areas in the city of Belém, Pará, Brazil, a case of cerebral filariasis was observed. In the course of histopathological examination, adult filariae were found in pseudocystic cavities brain of Molossus barnesi (Molossidae) and classified morphologically as Litomosoides by the shape of the spicules-left spicule with a handle longer than the blade; right spicule curved, with a sclerotized heel supporting a dorsal notch; the area rugosa constituted by a ventral band of small longitudinal crests; tail rounded in males; long esophagus with a slightly glandular distal portion; and a muscular bent vagina. All the specimens lack a stoma (buccal capsule). We compared our filarioids with the description of specimens of Molossinema wimsatti. Morphological characteristics of M. wimsatti resemble the genus Litomosoides. Thus, we believe that M. wimsatti is a synonym of L. molossi Esslinger, 1973, and filarioid specimens from material reported by Lichtenfels et al. (Trans Am Micros Soc 100:216-219, 1981) and from de Souto et al. (J. Helminthol 1195:e65, 2021) most probably correspond to Litomosoides. We suggest that the reduction of the buccal capsule may be attributable to the ectopic location. No evidence of tissue responses by the host was observed. This is the first record of Litomosoides infecting brain tissue of Molossus barnesi from Brazil, representing a record of a new host species. More specimens of bats should be examined in order to find filarioids in the brain and verify its taxonomic position using molecular techniques.

Structural basis of substrate progression through the bacterial chaperonin cycle.

The bacterial chaperonin GroEL-GroES promotes protein folding through ATP-regulated cycles of substrate protein binding, encapsulation, and release. Here, we have used cryoEM to determine structures of GroEL, GroEL-ADP·BeF3, and GroEL-ADP·AlF3-GroES all complexed with the model substrate Rubisco. Our structures provide a series of snapshots that show how the conformation and interactions of non-native Rubisco change as it proceeds through the GroEL-GroES reaction cycle. We observe specific charged and hydrophobic GroEL residues forming strong initial contacts with non-native Rubisco. Binding of ATP or ADP·BeF3 to GroEL-Rubisco results in the formation of an intermediate GroEL complex displaying striking asymmetry in the ATP/ADP·BeF3-bound ring. In this ring, four GroEL subunits bind Rubisco and the other three are in the GroES-accepting conformation, suggesting how GroEL can recruit GroES without releasing bound substrate. Our cryoEM structures of stalled GroEL-ADP·AlF3-Rubisco-GroES complexes show Rubisco folding intermediates interacting with GroEL-GroES via different sets of residues.

Tapping into natural history collections to assess latitudinal gradients of parasite diversity.

Parasites are key components of the biosphere not only due to their huge diversity, but also because they exert important influences on ecological processes. Nevertheless, we lack an understanding of the biogeographical patterns of parasite diversity. Here, we tap into the potential of biodiversity collections for understanding parasite biogeography. We assess species richness of supracommunities of helminth parasites infecting mammal assemblages in the Nearctic, and describe its relation to latitude, climate, host diversity, and land area. We compiled data from parasitology collections and assessed parasite diversity in Nearctic ecoregions for the entire parasite supracommunity of mammals in each ecoregion, as well as separately from carnivores and rodents to explore the effect of host taxonomic resolution on observed patterns. For carnivores, we found evidence of a negative latitudinal gradient, while parasites of rodents displayed no clear pattern. We found that parasite diversity was positively correlated with mean annual temperature and negatively correlated with seasonal precipitation. Parasite richness shows a diversity peak at intermediate host richness values and in carnivores correlates with temperature and seasonal precipitation. Rodent parasite diversity did not correlate with explored factors. Other researchers are encouraged to use parasitology collections to continue exploring patterns of parasite biogeography and macroecology.

Structure of the transmembrane protein 2 (TMEM2) ectodomain and its apparent lack of hyaluronidase activity.

Background: Hyaluronic acid (HA) is a major polysaccharide component of the extracellular matrix. HA has essential functions in tissue architecture and the regulation of cell behaviour. HA turnover needs to be finely balanced. Increased HA degradation is associated with cancer, inflammation, and other pathological situations. Transmembrane protein 2 (TMEM2) is a cell surface protein that has been reported to degrade HA into ~5 kDa fragments and play an essential role in systemic HA turnover. Methods: We produced the soluble TMEM2 ectodomain (residues 106-1383; sTMEM2) in human embryonic kidney cells (HEK293) and determined its structure using X-ray crystallography. We tested sTMEM2 hyaluronidase activity using fluorescently labelled HA and size fractionation of reaction products. We tested HA binding in solution and using a glycan microarray. Results: Our crystal structure of sTMEM2 confirms a remarkably accurate prediction by AlphaFold. sTMEM2 contains a parallel ß-helix typical of other polysaccharide-degrading enzymes, but an active site cannot be assigned with confidence. A lectin-like domain is inserted into the ß-helix and predicted to be functional in carbohydrate binding. A second lectin-like domain at the C-terminus is unlikely to bind carbohydrates. We did not observe HA binding in two assay formats, suggesting a modest affinity at best. Unexpectedly, we were unable to observe any HA degradation by sTMEM2. Our negative results set an upper limit for k cat of approximately 10 -5 min -1. Conclusions: Although sTMEM2 contains domain types consistent with its suggested role in TMEM2 degradation, its hyaluronidase activity was undetectable. HA degradation by TMEM2 may require additional proteins and/or localisation at the cell surface.

Helminth and protozoan parasites of subterranean rodents (Chordata, Mammalia, Rodentia) of the world.

Published studies and ten new unpublished records included herein reveal that approximately 174 species of endoparasites (helminths and protozoans) are known from 65 of 163 species of rodents that occupy the subterranean ecotope globally. Of those, 94 endoparasite species were originally described from these rodents. A total of 282 host-parasite associations are summarized from four major zoogeographic regions including Ethiopian, Palearctic/Oriental, Nearctic, and Neotropical. Thirty-four parasite records from the literature have been identified to only the level of the genus. In this summary, ten new records have been added, and the most current taxonomic status of each parasite species is noted. Interestingly, there are no data on endoparasites from more than 68% of described subterranean rodents, which indicates that discovery and documentation are at an early stage and must continue.

"Revisiting the past": a redescription of Physaloptera retusa (Nemata, Physalopteridae) from material deposited in museums and new material from Amazon lizards.

Physaloptera Rudolphi, 1819 is a genus of nematodes that includes approximately 100 species parasitic in vertebrates around the world. From these, approximately 30 occur in the Neotropical region, with nine reported from neotropical reptiles. Physaloptera spp. are recognized by their distinct morphology of the apical end and characters of the reproductive system. However, despite the fact that the morphological characters for species diagnosis have been firmly established, we frequently find identification problems regarding poorly detailed descriptions and poorly preserved specimens. These may lead to taxonomic incongruencies. Physaloptera retusa (Rudolphi, 1819) is the most common species of the genus and has been reported from several species of neotropical reptiles. Based on our reexaminations of nematode specimens identified as P. retusa from different museum collections, we provide a detailed redescription including the type material, voucher specimens and new specimens recovered currently and showed in this study with new morphological data obtained using light and scanning electron microscopy tools.

Intercontinental comparisons of subterranean host-parasite communities using bipartite network analyses.

Rodents living in a subterranean ecotope face a unique combination of evolutionary and ecological pressures and while host species evolution may be driven by the selective pressure from the parasites they harbour, the parasites may be responding to the selective pressures of the host. Here, we obtained all available subterranean rodent host­parasite records from the literature and integrated these data by utilizing a bipartite network analysis to determine multiple critical parameters to quantify and measure the structure and interactions of the organisms present in host­parasite communities. A total of 163 species of subterranean rodent hosts, 174 parasite species and 282 interactions were used to create 4 networks with data well-represented from all habitable continents. The results show that there was no single species of parasite that infects subterranean rodents throughout all zoogeographical regions. Nevertheless, species representing the genera Eimeria and Trichuris were common across all communities of subterranean rodents studied. Based on our analysis of host­parasite interactions across all communities studied, the parasite linkages show that community connectance (due to climate change or other anthropogenic factors) appears to show degraded linkages in both the Nearctic and Ethiopian regions: in this case parasites are acting as bell-weather probes signalling the loss of biodiversity.

Structural basis for membrane attack complex inhibition by CD59.

CD59 is an abundant immuno-regulatory receptor that protects human cells from damage during complement activation. Here we show how the receptor binds complement proteins C8 and C9 at the membrane to prevent insertion and polymerization of membrane attack complex (MAC) pores. We present cryo-electron microscopy structures of two inhibited MAC precursors known as C5b8 and C5b9. We discover that in both complexes, CD59 binds the pore-forming ß-hairpins of C8 to form an intermolecular ß-sheet that prevents membrane perforation. While bound to C8, CD59 deflects the cascading C9 ß-hairpins, rerouting their trajectory into the membrane. Preventing insertion of C9 restricts structural transitions of subsequent monomers and indirectly halts MAC polymerization. We combine our structural data with cellular assays and molecular dynamics simulations to explain how the membrane environment impacts the dual roles of CD59 in controlling pore formation of MAC, and as a target of bacterial virulence factors which hijack CD59 to lyse human cells.

Investigating relationships between climate controls and nutrient flux in surface waters, sediments, and subsurface pathways in an agricultural clay catchment of the Great Lakes Basin.

Water quality within agricultural catchments is governed by management practices and climate conditions that control the transport, storage, and exchange of nutrients between components of the hydrologic cycle. This study aims to improve knowledge of nitrogen (N) and phosphorus (P) transport in low permeability agricultural watersheds by considering spatial and temporal trends of surface water nutrient concentrations in relation to hydroclimatic drivers, sediment quality, shallow hyporheic exchange, groundwater quality, and tile drain discharge over a 14-month field study in a clay hydrosystem of the Lake Huron basin, one of the five Great Lakes. Results found that events of varying magnitude and intensity enhanced nutrient release from overland flow and subsurface pathways. Tile drain discharge was found to be a consistent and elevated source of P and N to surface waters when flowing, mobilizing both diffuse nutrients from fertilizer application and legacy stores in the vadose zone. Surface water quality was temporally variable at the seasonal and event scale. Targeted sampling following fertilization periods, snowmelt, and moderate precipitation events revealed catchment wide elevated nutrient concentrations, emphasizing the need for targeted sampling regimes. Controls other than discharge magnitude and overland flow were found to contribute to peak nutrient concentrations, including internal nitrate loading, soil-snowmelt interaction, catchment wetness, and freeze thaw cycles. Sediments were found to store P in calcium minerals and have a high P storage capacity. Instream mechanisms such as sediment P fixation and hyporheic exchange may play a role in mediating surface water quality, but currently have no discernable benefit to year-round surface water nutrient concentrations. Best management practices need to focus on reducing sources of agricultural nutrients (e.g., field phosphorus concentrations and tile drain discharge loading) at the watershed scale to reduce nutrient concentrations and export in flashy clay catchments.

Structural insights into the assembly and activation of the IL-27 signaling complex.

Interleukin 27 (IL-27) is a heterodimeric cytokine that elicits potent immunosuppressive responses. Comprised of EBI3 and p28 subunits, IL-27 binds GP130 and IL-27Rα receptor chains to activate the JAK/STAT signaling cascade. However, how these receptors recognize IL-27 and form a complex capable of phosphorylating JAK proteins remains unclear. Here, we used cryo electron microscopy (cryoEM) and AlphaFold modeling to solve the structure of the IL-27 receptor recognition complex. Our data show how IL-27 serves as a bridge connecting IL-27Rα (domains 1-2) with GP130 (domains 1-3) to initiate signaling. While both receptors contact the p28 component of the heterodimeric cytokine, EBI3 stabilizes the complex by binding a positively charged surface of IL-27Rα and Domain 1 of GP130. We find that assembly of the IL-27 receptor recognition complex is distinct from both IL-12 and IL-6 cytokine families and provides a mechanistic blueprint for tuning IL-27 pleiotropic actions.

Less Is More: A Multimodal Pain Management Strategy Is Associated With Reduced Opioid Use in Hospitalized Trauma Patients.

INTRODUCTION: Adequate pain control is critical to the management and recovery of acutely injured patients. Opioids are associated with various adverse effects, and drug overdose is the leading cause of injury-related death in the United States. We hypothesized that a multimodal pain management protocol would reduce opioid use while still optimizing pain control. METHODS: The study included the preanalysis (August 2017-September 2018) and postanalysis (October 2018-August 2019) of a multimodal pain management strategy implemented in hospitalized adult patients admitted to the trauma service at a single American College of Surgeons-verified level-1 trauma center. Patients less than 18 y of age, pregnant patients, or imprisoned patients were excluded. The primary endpoint was opioid prescription on discharge (morphine milligram equivalent [MME]). The secondary endpoints included inpatient MMEs, nonopioid adjunct use, and pain scores. Subgroup analysis evaluating opioid use based on Injury Severity Score groups (mild, moderate, or severe) and by the Abbreviated Injury Scale body region was performed. RESULTS: There were 1755 patients in the PRE group and 1723 patients in the POST group. MMEs prescribed on discharge decreased from median 15 (interquartile range: 37.5) to 1.2 (interquartile range: 22.5) (P < 0.001). More patients in the POST group were discharged opioid-free (44% versus 37%, P < 0.001). There was a significant increase in the use of all nonopioid pain medications. Pain scores did not change. Subgroup analysis revealed a significant decrease in discharge MMEs in mild and moderate Injury Severity Score groups and in all injured body regions except the chest. CONCLUSIONS: The implementation of a multimodal pain management protocol in trauma patients targeting scheduled nonopioid medications and patient education is feasible and is associated with reduced opioid amount prescribed on discharge, without compromising pain control.

Long-Term Impact of Interprofessional Medical Mission Service Trips in Sierra Leone.

Objective: The purpose of this study was to evaluate the impact of capacity-building short-term mission service trips to Sierra Leone on local health education and perspectives. Methods: This was a prospective, mixed-methods study. During three mission trips between June 2017 and December 2019, health professional students taught multiple locally selected patient care-related topics. Local staff completed knowledge questionnaires and were surveyed or interviewed on mission service impact along with the cultural competence of missionaries. Mission team members completed the Intercultural Effectiveness Scale (IES) and surveys to determine their cultural competence. Results: After initial education, 90% passed the knowledge questionnaire with at least a 50% and the correct response rate was 57.9 vs. 66.7% after 6 months and 2.5 years, respectively (p = 0.40). Local staff ranked education/training as most valuable (84%) and highly desired (53%). Mean IES score and survey responses of both missionaries and local staff rated mission team cultural competence as average. Conclusions: Education-focused mission trips in Sierra Leone seem to have long-lasting benefits and a positive impact on local staff, though improved intercultural competence is needed.

Readmission for pleural space complications after chest wall injury: Who is at risk?

BACKGROUND: Little is known about patient characteristics predicting postdischarge pleural space complications (PDPSCs) after thoracic trauma. We sought to analyze the patient population who required unplanned hospital readmission for PDPSC. METHODS: Retrospective review of adult patients admitted to a Level I Trauma Center with a chest Abbreviated Injury Scale (AIS) score of 2 or greater between January 2015 and August 2020. Those readmitted within 30 days of index hospitalization discharge for PDPSC were compared with those not readmitted. Demographics, injury characteristics, surgical procedures, imaging, and readmission data were retrieved. RESULTS: Out of 17,192 trauma evaluations, 3,412 (19.8%) suffered a chest AIS score of 2 or greater injury and 155 experienced an unplanned 30-day hospital readmission. Of those, 49 (1.4%) were readmitted for the management of PDPSC (readmit PDPSC) and were compared with patients who were not readmitted (no readmit, n = 3,257). The readmit PDPSC group was significantly older age, heavier, comprised of fewer men, and suffered a higher mean chest AIS score. The readmit PDPSC group had a significantly higher incidence of rib fractures, flail chest, pneumothorax, hemothorax, scapula fractures, and a higher rate of tube thoracostomy placement during index admission. The discharge chest X-ray in the readmit PDPSC group demonstrated a pleural space abnormality in 36 (73%) of patients. Mean time to readmission was 10.2 (7.2) days, and hospital length of stay on readmission was 5.8 (3.7) days. Pleural effusion was the most common readmission diagnosis (44 [90%]), and 42 (86%) required tube thoracostomy. CONCLUSION: We describe the subset of chest wall injury patients who require hospital readmission for PDPSC. Characteristics from index hospitalization associated with PDPSC include older age, female sex, heavier weight, presence of rib fractures, pleural space abnormality, scapular fracture, and chest tube placement. Further studies are needed to characterize this at-risk chest wall injury population, and to determine what interventions can facilitate outpatient management of postdischarge pleural space complications and mitigate readmission risk. LEVEL OF EVIDENCE: Prognostic and epidemiologic, Level IV; Care management, Level V.

Surgical stabilization of rib fractures in octogenarians and beyond-what are the outcomes?

BACKGROUND: Prospective studies of surgical stabilization of rib fractures (SSRF) have excluded elderly patients, and no study has exclusively addressed the ≥80-year-old subgroup. We hypothesized that SSRF is associated with decreased mortality in trauma patients 80 years or older. METHODS: Multicenter retrospective cohort study involving eight centers. Patients who underwent SSRF from 2015 to 2020 were matched to controls by study center, age, injury severity score, and presence of intracranial hemorrhage. Patients with chest Abbreviated Injury Scale score less than 3, head Abbreviated Injury Scale score greater than 2, death within 24 hours, and desire for no escalation of care were excluded. A subgroup analysis compared early (0-2 days postinjury) to late (3-7 days postinjury) SSRF. Poisson regression accounting for clustered data by center calculated the relative risk (RR) of the primary outcome of mortality for SSRF versus nonoperative management. RESULTS: Of 360 patients, 133 (36.9%) underwent SSRF. Compared with nonoperative patients, SSRF patients were more severely injured and more likely to receive locoregional analgesia. There were 31 hospital deaths among the entire sample (8.6%). Multivariable regression demonstrated a decreased risk of mortality for the SSRF group, as compared with the nonoperative group (RR, 0.41; 95% confidence interval, 0.24-0.69; p < 0.01). However, SSRF patients were more likely to develop pneumonia, and had an increased duration of both mechanical ventilation and intensive care unit stay. There were no differences in discharge destination, although the SSRF group was less likely to be discharged on narcotics (RR, 0.66; 95% confidence interval, 0.48-0.90; p = 0.01). There was no difference in adjusted mortality between the early and late SSRF subgroups. CONCLUSION: Patients selected for SSRF were substantially more injured versus those managed nonoperatively. Despite this, SSRF was independently associated with decreased mortality. With careful patient selection, SSRF may be considered a viable treatment option in octogenarian/nonagenarians. LEVEL OF EVIDENCE: Therapeutic, Level IV.

HOST-SWITCHING EVENTS IN LITOMOSOIDES CHANDLER, 1931 (FILARIOIDEA: ONCHOCERCIDAE) ARE NOT RAMPANT BUT CLADE DEPENDENT.

The genus Litomosoides Chandler, 1931, includes species that as adults occur in the thoracic and abdominal cavity of mammalian hosts and are presumably vectored by mites. The vertebrate hosts include a variety of Neotropical mammals such as phyllostomid and mormoopid bats; cricetid, sciurid, and hystricognath rodents; and didelphid marsupials. It has been suggested that Litomosoides is not a monophyletic group and that rampant horizontal transfer explains their presence in disparate groups of mammals. Herein we present a phylogenetic reconstruction including mitochondrial genes of 13 vouchered species. This phylogeny is used to reconstruct the evolutionary history of these parasites and the ancestral states of key characters used in species classification, namely, the configuration of the spicules. The historical association of these filarioids with 6 groups of mammals, as well as their ancestral geographic distributions, were reconstructed using Bayesian statistical approaches comparing alternative models of biogeography and evolution and fossil states in selected nodes of the phylogeny. The optimal reconstruction suggests a model of dispersal, extinction, and cladogenesis (DEC) driving the evolution of Litomosoides; the results suggest an origin of Litomosoides in South America and association of ancestors with phyllostomids, and strong evidence of at least 2 host-switching events: 1 of these involving cricetid rodents and the other mormoopid bats. The latter event included a simultaneous geographic expansion of the parasite lineage across South and North America. The host-switching event from phyllostomid bats into cricetid rodents occurred once these rodents diversified across South America; subsequent diversification of the latter clade resulted in 2 branches, each showing expansion of the parasites back into North America. This result suggests that both parasites and cricetid rodents established an association in South America, underwent diversification, and then dispersed into North America. Further, this clade of cricetid-dwelling species includes parasites featuring the "sigmodontis" spicule type. The identification of a single host-switching event involving the disparate lineages of Chiroptera and Rodentia offers a framework to reconstruct the gene evolution and diversification of this lineage after the host-switching event. This will help in predicting the ability of these parasites to infect sympatric mammals.

Characterization and influence of ipsilateral scapula fractures among patients who undergo surgical stabilization of sub-scapular rib fractures.

BACKGROUND: Current decision algorithms involving surgical stabilization of rib fractures (SSRF) do not consider either specific fracture locations or other chest wall bony injuries. Our objective was to characterize the impact of scapula fractures on morbidity among patients who underwent fixation of sub-scapular rib fractures. We hypothesized that an ipsilateral scapula fracture was associated with poor acute and long-term outcomes. METHODS: Retrospective review of two institutions' prospectively maintained SSRF databases (October 2010 to January 2019). Patients who underwent repair of ≥ 1 sub-scapular rib fracture were included. Patients were grouped by the presence of an ipsilateral scapula fracture. Outcomes were acute SSRF complications, long-term rib implant removal, and quality of life via phone survey. RESULTS: A total of 144 patients were analyzed; 53 (36.8%) had an ipsilateral scapula fracture. Patients with a scapula fracture had a higher injury severity score (p = 0.02), degree of pulmonary contusion (p < 0.01), and RibScore (p < 0.01). The overall incidence of both acute re-operation (n = 4, 2.8%) and long-term implant removal (n = 5, 3.8%) following SSRF was low and did not vary by the presence of a scapula fracture. Only twenty-one patients completed phone questionnaires a median of 38 months after SSRF; both shoulder and rib outcomes were excellent and did not vary by the presence of a scapula fracture. CONCLUSION: Ipsilateral scapula fractures are common in patients who undergo surgical stabilization of sub-scapular rib fractures. Despite higher injury severity, patients with an ipsilateral scapula fracture did not incur worse outcomes.

A new genus and two new species of unarmed hymenolepidid cestodes (Cestoda: Hymenolepididae) from geomyid rodents in Mexico and Costa Rica.

Two new cestodes of the family Hymenolepididae are described from two species of rodents of the family Geomyidae collected in Mexico and Costa Rica. One new species of Hymenolepis is described from Cratogeomys planiceps Merriam 1895 from near Toluca, Mexico and another that we allocate to a new genus is described from Heterogeomys heterodus (Peters, 1865) from near Irazú Volcano, Costa Rica. Hymenolepis s. str. includes those Hymenolepididae with an apical organ, with no hooks on suckers or apical organ, and three testes. Hobergia irazuensis n. gen., n. sp. includes a hymenolepidid with an apical organ, unarmed scolex, small pockets termed foveolae, in which the suckers completely retract, and extremely bi-lobed ovary. Multivariate morphometric analysis showed good separation of these species from all other hymenolepidids possessing an apical organ and lacking a well developed rostellum and rostellar hooks in the Nearctic and Neotropical regions.