Investigating the effect of fusion partners on the enzymatic activity and thermodynamic stability of poly(ethylene terephthalate) degrading enzymes.

Plastics are a cornerstone of the modern world, yet the durable material properties that we have come to depend upon have made them recalcitrant environmental pollutants. Biological solutions in the form of engineered enzymes offer low energy and sustainable approaches to recycle and upcycle plastic waste, uncoupling their production and end of life from fossil fuels and greenhouse gases. These enzymes however, encounter immense challenges acting on plastics: facing hydrophobic surfaces, molecular crowding, and high levels of substrate heterogeneity. There have been mixed reports about the benefits of fusing partner domains to polyethylene terephthalate (PET) degrading enzymes, with moderate improvements identified under specific conditions, but no clarity into the factors that underlie the mechanisms. Here, we use the SpyCatcher003:SpyTag003 technology, which demonstrates a profound 47 °C shift in Tm upon irreversible complex formation, to investigate the influence of the thermal stability of the fusion partner on a range of PETases selected for their optimal reaction temperatures. We find that the thermal stability of the fusion partner does not have a positive correlation on the activity of the enzymes or their evident kinetic and thermal stabilities. Instead, it appears that the fusion to less stable SpyCatcher003 tends to increase the measured activation energy of unfolding compared to the more stable complex and wildtype enzymes. Despite this, the fusions to SpyCatcher003 do not show significantly better catalytic activity on PET films, with or without SpyTag003, and were found to be sometimes disruptive. The approach we highlight here, in using a fusion partner with controllable melting temperature, allowed us to dissect the impact of the stability of a fusion partner on enzyme properties. Although fusion stability did not appear to be coupled with identifiable trends in enzymatic activities, careful analysis of the unfolding pathways, and solid and solution activities of a wider range of enzymes may yield a more detailed understanding.

Advancing arteriovenous fistula needling: The role of physical exam and doppler ultrasound.

BACKGROUND: The success of haemodialysis (HD) critically depends on the effective use of arteriovenous fistulas (AVFs). The precise needling technique is vital to minimise complications and ensure functional vascular access. OBJECTIVE: This study assesses the effectiveness of a nursing consultation protocol, which integrates physical examination (PE) with Doppler Ultrasound (DUS), in preparing patients for the first AVF needling. DESIGN/PARTICIPANTS: A cross-sectional analysis at a Portuguese National Health Service Hospital engaged thirty new HD patients, four HD needling experienced nurses and one HD vascular access nurse. This study examines the accuracy of PE in assessing the matured AVF by the four nurses compared to a trained vascular access nurse encompassing systematic PE and DUS. MEASUREMENTS: The primary data incorporated AVF characteristics derived from PE (inspection, palpation, and auscultation) and DUS findings (vein depth, diameter, and blood flow). A secondary focus was evaluating the change in nurses' perceived needling complexity following the nursing consultation. RESULTS: The nursing consultation significantly enhanced the identification of crucial AVF features, such as accessory veins (p = 0.002), and improved the accuracy of AVF morphology assessments. This led to identifying longer needling tracks (p = 0.031) and a higher number of safe needling points (p = 0.016). Nurses reported a notable reduction in perceived complexity and potential adverse events following this method (p = 0.027). CONCLUSIONS: Integrating structured PE with DUS in a nursing consultation framework significantly improves the preparation for AVF needling. This approach enhances the efficiency and safety of AVF needling and boosts nurse confidence and patient care in HD settings.

CD5L as a promising biological therapeutic for treating sepsis.

Sepsis results from systemic, dysregulated inflammatory responses to infection, culminating in multiple organ failure. Here, we demonstrate the utility of CD5L for treating experimental sepsis caused by cecal ligation and puncture (CLP). We show that CD5L's important features include its ability to enhance neutrophil recruitment and activation by increasing circulating levels of CXCL1, and to promote neutrophil phagocytosis. CD5L-deficient mice exhibit impaired neutrophil recruitment and compromised bacterial control, rendering them susceptible to attenuated CLP. CD5L-/- peritoneal cells from mice subjected to medium-grade CLP exhibit a heightened pro-inflammatory transcriptional profile, reflecting a loss of control of the immune response to the infection. Intravenous administration of recombinant CD5L (rCD5L) in immunocompetent C57BL/6 wild-type (WT) mice significantly ameliorates measures of disease in the setting of high-grade CLP-induced sepsis. Furthermore, rCD5L lowers endotoxin and damage-associated molecular pattern (DAMP) levels, and protects WT mice from LPS-induced endotoxic shock. These findings warrant the investigation of rCD5L as a possible treatment for sepsis in humans.

The CD6 interactome orchestrates ligand-independent T cell inhibitory signaling.

BACKGROUND: T-cell membrane scaffold proteins are pivotal in T cell function, acting as versatile signaling hubs. While CD6 forms a large intracellular signalosome, it is distinguished from typical scaffolds like LAT or PAG by possessing a substantial ectodomain that binds CD166, a well-characterized ligand expressed on most antigen-presenting cells (APC), through the third domain (d3) of the extracellular region. Although the intact form of CD6 is the most abundant in T cells, an isoform lacking d3 (CD6∆d3) is transiently expressed on activated T cells. Still, the precise character of the signaling transduced by CD6, whether costimulatory or inhibitory, and the influence of its ectodomain on these activities are unclear. METHODS: We expressed CD6 variants with extracellular deletions or cytosolic mutations in Jurkat cells containing eGFP reporters for NF-κB and NF-AT transcription factor activation. Cell activation was assessed by eGFP flow cytometry following Jurkat cell engagement with superantigen-presenting Raji cells. Using imaging flow cytometry, we evaluated the impact of the CD6-CD166 pair on cell adhesiveness during the antigen-dependent and -independent priming of T cells. We also examined the role of extracellular or cytosolic sequences on CD6 translocation to the immunological synapse, using immunofluorescence-based imaging. RESULTS: Our investigation dissecting the functions of the extracellular and cytosolic regions of CD6 revealed that CD6 was trafficked to the immunological synapse and exerted tonic inhibition wholly dependent on its cytosolic tail. Surprisingly, however, translocation to the synapse occurred independently of the extracellular d3 and of engagement to CD166. On the other hand, CD6 binding to CD166 significantly increased T cell:APC adhesion. However, this activity was most evident in the absence of APC priming with superantigen, and thus, in the absence of TCR engagement. CONCLUSIONS: Our study identifies CD6 as a novel 'on/off' scaffold-receptor capable of modulating responsiveness in two ways. Firstly, and independently of ligand binding, it establishes signaling thresholds through tonic inhibition, functioning as a membrane-bound scaffold. Secondly, CD6 has the capacity for alternative splicing-dependent variable ligand engagement, modulating its checkpoint-like activity.

Parasacral transcutaneous electrical neural stimulation versus urotherapy in primary monosymptomatic enuresis: A prospective randomized clinical trial.

OBJECTIVE: To evaluate the clinical response of parasacral transcutaneous electrical neural stimulation (parasacral TENS) associated with urotherapy in children with primary monosymptomatic nocturnal enuresis (PMNE) compared to urotherapy alone. MATERIAL AND METHODS: This prospective controlled clinical trial enrolled 72 children over 5 years of age with PMNE. Children were randomly divided into two groups, control group (CG), treated with urotherapy and scapular stimulation, and experimental group (EG), treated with urotherapy and parasacral TENS. In both groups, 20 sessions were performed, 3 times weekly, for 20 min each, with 10 Hz frequency, 700 µS pulse width and intesity determinated by the patient threshold. The percentages of dry nights were analyzed for 14 days before treatment (T0), after the 20th session (T1), 15 (T2), 30 (T3), 60 (T4), and 90 (T5) days after the end of the sessions. Patients of both groups were followed with intervals of 2 weeks in the first month and monthly for three consecutive months. RESULTS: Twenty-eight enuretic children, 14 girls (50%) with a mean age of 9.09 ± 2.23 years completed the study. There was no difference in mean age between groups. Mean percentage of dry nights in EG at T0 was 36%, at T1 49%, at T2 54%, at T3 54%, at T4 54%, and 57% at T5; while in CG, these percentages were 28%, 39%, 37%, 35%, 36%, and 36%, respectively. CONCLUSIONS: Parasacral TENS associated with urotherapy improves the percentage of dry nights in children with PMNE, although no patient had complete resolution of symptoms in this study.

Video Capsule Endoscopy can Identify Occult Luminal Crohn's Disease in Patients with Isolated Perianal Fistulas.

BACKGROUND: Accurate tools to distinguish Crohn's disease [CD] from cryptoglandular disease in patients with perianal fistulas without detectable luminal inflammation on ileocolonoscopy and abdominal enterography (isolated perianal fistulas [IPF]) are lacking. We assessed the ability of video capsule endoscopy [VCE] to detect luminal inflammation in patients with IPF. METHODS: We studied consecutive adults [>17 years] with IPF who were evaluated by VCE after a negative ileocolonoscopy and abdominal enterography between 2013 and 2022. We defined luminal CD by VCE as diffuse erythema, three or more aphthous ulcers, or a Lewis score greater than 135. We compared rates of intestinal inflammation in this cohort with age- and sex-matched controls without perianal fistulas, who underwent VCE for other indications. We excluded persons with pre-existing inflammatory bowel disease [IBD] and exposure to non-steroidal anti-inflammatory drugs or immunosuppressive treatments. RESULTS: A total of 45 patients with IPF underwent VCE without complications. Twelve patients [26%] met our definition of luminal CD. Luminal CD was more common in patients with IPF than in controls [26% vs 3%; p <0.01]. Among patients with IPF, male sex (OR [odds ratio], 9.2; 95% confidence interval [CI] [1.1-79.4]), smoking (OR, 4.5; 95% CI [0.9-21.2]), abscess (OR, 6.3; 95% CI [1.5-26.8]), rectal enhancement on magnetic resonance imaging [MRI] (OR, 9.0; 95% CI [0.8-99.3]), and positive antimicrobial serology (OR, 7.1; 95% CI, [0.7-70.0]) were more common in those with a positive VCE study. CONCLUSIONS: VCE detected small intestinal inflammation suggestive of luminal CD in approximately one-quarter of patients with IPF. Larger studies are required to validate these findings.

Concentration-Dependent Inhibition of Mesophilic PETases on Poly(ethylene terephthalate) Can Be Eliminated by Enzyme Engineering.

Enzyme-based depolymerization is a viable approach for recycling of poly(ethylene terephthalate) (PET). PETase from Ideonella sakaiensis (IsPETase) is capable of PET hydrolysis under mild conditions but suffers from concentration-dependent inhibition. In this study, this inhibition is found to be dependent on incubation time, the solution conditions, and PET surface area. Furthermore, this inhibition is evident in other mesophilic PET-degrading enzymes to varying degrees, independent of the level of PET depolymerization activity. The inhibition has no clear structural basis, but moderately thermostable IsPETase variants exhibit reduced inhibition, and the property is completely absent in the highly thermostable HotPETase, previously engineered by directed evolution, which simulations suggest results from reduced flexibility around the active site. This work highlights a limitation in applying natural mesophilic hydrolases for PET hydrolysis and reveals an unexpected positive outcome of engineering these enzymes for enhanced thermostability.

One-day voiding diary in the evaluation of Lower Urinary Tract Symptoms in children

ABSTRACT Introduction: Voiding diary (VD) is an important tool in the evaluation of children with voiding symptoms. Voiding frequency, maximal voided volume (MVV), average voided volume (AVV) and nocturnal volume (NV) can be extracted and are valuable in diagnosing and monitoring these disorders. Recently, ICCS has reduced the period of data recording on VD from 3 to 2 days. We hypothesized that one day voiding diary would be enough for guiding treatment. Materials and Methods: Children with overactive bladder (OAB) and primary monosymptomatic enuresis (PMNE) were oriented to fulfill a 3-day VD. Data obtained from VD were evaluated for the first day (1dVD), the first two days (2dVD), and all 3 days (3dVD) and compared according to the MVV, AVV, frequency, NV and expected bladder capacity (EBC). The Friedman, Student's t test and the Fisher's exact was used. ANOVA was used for multiple comparisons. We also used Pearson correlation test. Results: Ninety-eight children were included, 59 had PMNE and 30 OAB. Frequency, AVV and VN were similar regardless how many days the voiding episodes were recorded. Only MVV was higher by a mean of only 32 mL on 3dVD compared to 1dVD. A 1dVD has a sensitivity of 93,9% and a positive likelihood ratio of 2.2. As for the correlation of MVV and EBC it was observed that in 83% of children, MVV was lower than EBC. MVV corresponds to 67% and 69% of EBC in children with PMNE and OAB, respectively. Conclusion: We believe that 1dVD is sufficient to assess these children. It has a high sensitivity and good correlation to 3dVD in evaluating these children. Bladder capacity in this population, evaluated by maximum voided volume, was close to 68% of that obtained by the EBC.

One-day voiding diary in the evaluation of Lower Urinary Tract Symptoms in children.

INTRODUCTION: Voiding diary (VD) is an important tool in the evaluation of children with voiding symptoms. Voiding frequency, maximal voided volume (MVV), average voided volume (AVV) and nocturnal volume (NV) can be extracted and are valuable in diagnosing and monitoring these disorders. Recently, ICCS has reduced the period of data recording on VD from 3 to 2 days.We hypothesized that one day voiding diary would be enough for guiding treatment. MATERIALS AND METHODS: Children with overactive bladder (OAB) and primary monosymptomatic enuresis (PMNE) were oriented to fulfill a 3-day VD. Data obtained from VD were evaluated for the first day (1dVD), the first two days (2dVD), and all 3 days (3dVD) and compared according to the MVV, AVV, frequency, NV and expected bladder capacity (EBC). The Friedman, Student's t test and the Fisher's exact was used. ANOVA was used for multiple comparisons. We also used Pearson correlation test. RESULTS: Ninety-eight children were included, 59 had PMNE and 30 OAB. Frequency, AVV and VN were similar regardless how many days the voiding episodes were recorded. Only MVV was higher by a mean of only 32 mL on 3dVD compared to 1dVD. A 1dVD has a sensitivity of 93,9% and a positive likelihood ratio of 2.2. As for the correlation of MVV and EBC it was observed that in 83% of children, MVV was lower than EBC. MVV corresponds to 67% and 69% of EBC in children with PMNE and OAB, respectively. CONCLUSION: We believe that 1dVD is sufficient to assess these children. It has a high sensitivity and good correlation to 3dVD in evaluating these children. Bladder capacity in this population, evaluated by maximum voided volume, was close to 68% of that obtained by the EBC.

CD6-mediated inhibition of T cell activation via modulation of Ras.

BACKGROUND: CD6 is one of many cell surface receptors known to regulate signal transduction upon T cell activation. However, whether CD6 mediates costimulatory or inhibitory signals is controversial. When T cells engage with antigen presenting cells (APCs), CD6 interacts with its ligand CD166 at the cell-cell interface while the cytosolic tail assembles a complex signalosome composed of adaptors and effector enzymes, that may either trigger activating signaling cascades, or instead modulate the intensity of signaling. Except for a few cytosolic adaptors that connect different components of the CD6 signalosome, very little is known about the mechanistic effects of the cytosolic effectors that bind CD6. METHODS: Jurkat model T cells were transfected to express wild-type (WT) CD6, or a cytoplasmic truncation, signaling-disabled mutant, CD6Δcyt. The two resulting cell lines were directly activated by superantigen (sAg)-loaded Raji cells, used as APCs, to assess the net signaling function of CD6. The Jurkat cell lines were further adapted to express a FRET-based unimolecular HRas biosensor that reported the activity of this crucial GTPase at the immunological synapse. RESULTS: We show that deletion of the cytosolic tail of CD6 enhances T-cell responses, indicating that CD6 restrains T-cell activation. One component of the CD6-associated inhibitory apparatus was found to be the GTPase activating protein of Ras (RasGAP), that we show to associate with CD6 in a phosphorylation-dependent manner. The FRET HRas biosensor that we developed was demonstrated to be functional and reporting the activation of the T cell lines. This allowed to determine that the presence of the cytosolic tail of CD6 results in the down-regulation of HRas activity at the immunological synapse, implicating this fundamental GTPase as one of the targets inhibited by CD6. CONCLUSIONS: This study provides the first description of a mechanistic sequence of events underlying the CD6-mediated inhibition of T-cell activation, involving the modulation of the MAPK pathway at several steps, starting with the coupling of RasGAP to the CD6 signalosome, the repression of the activity of Ras, and culminating in the reduction of ERK1/2 phosphorylation and of the expression of the T-cell activation markers CD69 and IL-2R α chain. Video abstract.

Physical Interactions With Bacteria and Protozoan Parasites Establish the Scavenger Receptor SSC4D as a Broad-Spectrum Pattern Recognition Receptor.

Since the pioneering discoveries, by the Nobel laureates Jules Hoffmann and Bruce Beutler, that Toll and Toll-like receptors can sense pathogenic microorganisms and initiate, in vertebrates and invertebrates, innate immune responses against microbial infections, many other families of pattern recognition receptors (PRRs) have been described. One of such receptor clusters is composed by, if not all, at least several members of the scavenger receptor cysteine-rich (SRCR) superfamily. Many SRCR proteins are plasma membrane receptors of immune cells; however, a small subset consists of secreted receptors that are therefore in circulation. We here describe the first characterization of biological and functional roles of the circulating human protein SSC4D, one of the least scrutinized members of the family. Within leukocyte populations, SSC4D was found to be expressed by monocytes/macrophages, neutrophils, and B cells, but its production was particularly evident in epithelial cells of several organs and tissues, namely, in the kidney, thyroid, lung, placenta, intestinal tract, and liver. Similar to other SRCR proteins, SSC4D shows the capacity of physically binding to different species of bacteria, and this opsonization can increase the phagocytic capacity of monocytes. Importantly, we have uncovered the capacity of SSC4D of binding to several protozoan parasites, a singular feature seldom described for PRRs in general and here demonstrated for the first time for an SRCR family member. Overall, our study is pioneer in assigning a PRR role to SSC4D.

Domain-specific CD6 monoclonal antibodies identify CD6 isoforms generated by alternative-splicing.

The characterization of the architecture, structure and extracellular interactions of the CD6 glycoprotein, a transmembrane receptor expressed in medullary thymocytes and all mature T-cell populations, has been enhanced by the existence of monoclonal antibodies (mAbs) that specifically recognize the various scavenger receptor cysteine-rich (SRCR) domains of the ectodomain. Using engineered isoforms of CD6 including or excluding each of the three SRCR domains, either expressed at the membranes of cells or in soluble forms, we provide conclusive and definitive evidence that domain 2 of CD6, previously not identifiable, can be recognized by the CD6 mAbs OX125 and OX126, and that OX124 targets domain 3 and can block the interaction at the cell surface of CD6 with its major ligand CD166. Alternative splicing-dependent CD6 isoforms can now be confidently identified. We confirm that following T-cell activation there is a partial replacement of full-length CD6 by the CD6Δd3 isoform, which lacks the CD166-binding domain, and we find no evidence for the expression of other CD6 isoforms at the mRNA or protein levels.

ThermoLabAnimal - A high-throughput analysis software for non-invasive thermal assessment of laboratory mice.

Body temperature changes in laboratory mice are often assessed by invasive and stressful methods, which may confound the measurement. Infrared thermography is a possible non-invasive alternative, but the cost of standard thermal cameras, lack of dedicated software for biomedical purposes, and labour-intensiveness of thermal image analysis have limited their use. An additional limitation lies on the scarcity of research on the causing factors of differences between body surface and core body temperature. We propose a method for automatic assessment of mean body surface temperature in freely-moving mice, using dedicated software for thermal image analysis. While skin surface temperature may not necessarily be linearly correlated with core body temperature (in itself an imprecise concept), under standardized environmental conditions, such as those in which laboratory animals are kept, mean body surface temperature can provide useful information on their thermal status (i.e. deviations from normothermia, namely hypo- and hyperthermia). We developed a publicly available software that includes an imaging analysis workflow/algorithm for automatic segmentation of the pixels associated with the animal from the pixels associated with the background, removing the need for manually defining the area of analysis. A batch analysis mode is also available, for automatic and high-throughput analysis of all image files located in a folder. The software is compatible with the most widespread thermal camera manufacturer, 'FLIR Systems', as well as with the low-cost 'Thermal Expert TE-Q1' miniaturized high-resolution thermal camera used for this study. Furthermore, the software has been validated in a mouse model expressing non-transient hypothermia, where the thermal analysis results were compared with readings from implanted thermo-sensitive passive integrated transponders tags. Thermography allows for thermal assessment of laboratory animals without the effect of handling stress on their physiology or behaviour. Our automatic image analysis software also removes observer errors and bias, while speeding up the data processing.

Palliative splenic irradiation for symptomatic splenomegaly in non-Hodgkin lymphoma.

INTRODUCTION AND AIMS: Splenic marginal zone lymphoma, an uncommon subtype of non-Hodgkin lymphoma (NHL), is usually present with symptomatic splenomegaly. Although splenectomy has long been considered the first-line therapy in symptomatic or cytopenic patients, it can lead to significant morbidity and mortality. Splenic irradiation is an option for patients who have a poor response to systemic therapy and/or are not surgical candidates. In this paper, we present a case report of a patient who received splenic radiotherapy for symptomatic splenomegaly. METHODS: An 85-year-old Caucasian man with a 4 year history of low-grade NHL presented with progressive pancytopenia, significant weight loss and symptomatic splenomegaly (abdominal discomfort, sense of fullness and limitation of mobility due to spleen size). The patient refused splenectomy and, in December 2017, was referred to palliative splenic radiotherapy. He was initially treated with five fractions of one Grey (Gy) in order to evaluate clinical and haematology response. After that, 1.5 Gy daily, 5 days a week for 3 weeks. 3D conformal radiotherapy, multiple fields and mixed energy (6 and 15 Mv) were used. RESULTS: Radiotherapy allowed significant splenic reduction to almost half the size, resolving abdominal discomfort and improving quality of life. There was no decline of haemoglobin, leukocytes and platelet counts; in fact, there was a marginal increase. CONCLUSION: Palliative splenic irradiation was well tolerated confirming that it is a safe treatment option for palliation of symptomatic splenomegaly. Thereby, splenic irradiation should be strongly considered in the management of symptomatic splenomegaly, for selected patients who are refractory to or unsuitable for other options or when the patient refuses other treatments.

Parasacral transcutaneous electrical neural stimulation (PTENS) once a week for the treatment of overactive bladder in children: A randomized controlled trial.

INTRODUCTION: Overactive bladder (OAB) is the most prevalent voiding disorder in childhood, and its main manifestation is urinary urgency. In general, urotherapy and anticholinergics are the first choices of treatment. Parasacral Transcutaneous Electrical Neural Stimulation (PTENS) was introduced as an alternative for the treatment of detrusor overactivity in children, but treatment protocols described to date require several sessions per week or long-lasting sessions, making it difficult for the child to adhere to the treatment. Thus, this study aims to evaluate the effectiveness of PTENS in single weekly sessions in the treatment of OAB in children. STUDY DESIGN: This prospective, randomized controlled trial included 16 children with OAB. Children were divided into two groups: CG (urotherapy and electrical stimulation placebo) and EG (urotherapy and PTENS). For both groups, therapy was delivered in 20 weekly sessions, of duration 20 min each. Placebo electrical stimulation was done in the scapular area. The children were evaluated prior to treatment (T1), at the end of the 20 sessions (T2), and 60 days after the completion of treatment (T3), with a 3-day voiding diary, visual analogue scale (VAS), Rome III diagnostic criteria, and the Bristol Scale. RESULTS: The groups were similar in age, gender, and ethnicity. In the initial assessment, all children, in both groups, had urgency and incontinence, 50% in each group had constipation, and enuresis was present in seven children (87.5%) in the EG and six (75%) in the CG. No differences were found between the groups regarding the volumetric measurements made in the voiding diary, urinary frequency and constipation evaluated by the Rome III criteria and the Bristol Scale. Sixty days after treatment, a significant improvement was found in the EG group (p = 0.03) regarding urgency (Table), as well as an increase in dry nights in those presenting with enuresis (p = 0.03). No difference was noted regarding urinary incontinence (Table). At the end of 20 sessions and after 60 days of treatment, those responsible for the children in the EG perceived greater improvement in symptoms measured by the VAS (p = 0.05 and 0.04, respectively). CONCLUSIONS: Our preliminary results demonstrate that PTENS performed in single weekly sessions is effective in treating the bladder for symptoms of urinary urgency and enuresis, and in the perception of those responsible for the children. Further studies with larger populations are needed to corroborate these results.

The Scavenger Receptor SSc5D Physically Interacts with Bacteria through the SRCR-Containing N-Terminal Domain.

The scavenger receptor cysteine-rich (SRCR) family comprises a group of membrane-attached or secreted proteins that contain one or more modules/domains structurally similar to the membrane distal domain of type I macrophage scavenger receptor. Although no all-inclusive biological function has been ascribed to the SRCR family, some of these receptors have been shown to recognize pathogen-associated molecular patterns (PAMP) of bacteria, fungi, or other microbes. SSc5D is a recently described soluble SRCR receptor produced by monocytes/macrophages and T lymphocytes, consisting of an N-terminal portion, which contains five SRCR modules, and a large C-terminal mucin-like domain. Toward establishing a global common role for SRCR domains, we interrogated whether the set of five SRCR domains of SSc5D displayed pattern recognition receptor (PRR) properties. For that purpose, we have expressed in a mammalian expression system the N-terminal SRCR-containing moiety of SSc5D (N-SSc5D), thus excluding the mucin-like domain likely by nature to bind microorganisms, and tested the capacity of the SRCR functional groups to physically interact with bacteria. Using conventional protein-bacteria binding assays, we showed that N-SSc5D had a superior capacity to bind to Escherichia coli strains RS218 and IHE3034 compared with that of the extracellular domains of the SRCR proteins CD5 and CD6 (sCD5 and sCD6, respectively), and similar E. coli-binding properties as Spα, a proven PRR of the SRCR family. We have further designed a more sensitive, real-time, and label-free surface plasmon resonance (SPR)-based assay and examined the capacity of N-SSc5D, Spα, sCD5, and sCD6 to bind to different bacteria. We demonstrated that N-SSc5D compares with Spα in the capacity to bind to E. coli and Listeria monocytogenes, and further that it can distinguish between pathogenic E. coli RS218 and IHE3034 strains and the non-pathogenic laboratory E. coli strain BL21(DE3). Our work thus advocates the utility of SPR-based assays as sensitive tools for the rapid screening of interactions between immune-related receptors and PAMP-bearing microbes. The analysis of our results suggests that SRCR domains of different members of the family have a differential capacity to interact with bacteria, and further that the same receptor can discriminate between different bacteria strains and species.