Structural Insights of PD-1/PD-L1 Axis: An In silico Approach.

BACKGROUND: Interaction of PD-1 protein (present on immune T-cell) with its ligand PD-L1 (over-expressed on cancerous cell) makes the cancerous cell survive and thrive. The association of PD-1/PD-L1 represents a classical protein-protein interaction (PPI), where receptor and ligand binding through a large flat surface. Blocking the PD-1/PDL-1 complex formation can restore the normal immune mechanism, thereby destroying cancerous cells. However, the PD-1/PDL1 interactions are only partially characterized. OBJECTIVE: We aim to comprehend the time-dependent behavior of PD-1 upon its binding with PD-L1. METHOD: The current work focuses on a molecular dynamics simulation (MDs) simulation study of apo and ligand bound PD-1. RESULTS: Our simulation reveals the flexible nature of the PD-1, both in apo and bound form. Moreover, the current study also differentiates the type of strong and weak interactions which could be targeted to overcome the complex formation. CONCLUSION: The current article could provide a valuable structural insight about the target protein (PD-1) and its ligand (PD-L1) which could open new opportunities in developing small molecule inhibitors (SMIs) targeting either PD-1 or PD-L1.

Innovative Fusion of Probiotics and Mouth Fresheners: Investigating Unaltered Growth, Microscopic Analysis, and Mucoadhesive Strength.

Since ancient times, mouth fresheners in many different forms have been used throughout the world. Traditional knowledge describes the health benefits of mouth fresheners, and contemporary science is now investigating their benefits. Claims have been made that mouth fresheners not only improve digestion but also promote oral health. Similar, but in a more profound sense, probiotics offer astounding advantages in treating many disorders. In certain cases, probiotics also offer prophylactic effects. Numerous benefits for dental health are being studied for B. coagulans (MB-BCM9) and B. subtilis (MB-BSM12). In this current study, a probiotic and a mouth freshener were combined to ameliorate the impacts of both. The oral residence of probiotics was enhanced by employing mucoadhesive polymers. Numerous compositions were developed and evaluated for the unaltered growth of probiotics, along with other evaluations like microscopy, in vitro mucoadhesive strength, and stability studies. Xanthan gum and hydroxypropyl methylcellulose were used in the development of mucoadhesive probiotic powder by employing the lyophilization technique. More than five hours of residence time were observed in the in vitro study with goat oral mucosa. The enumeration study validated the label claims of MB-BCM9 and MB-BSM12. It also concluded that none of the components of the formulation had a detrimental effect on probiotics. In essence, the present work discloses the novel and stable formulation of a probiotic-based mouth freshener.

Computational Exploration of Naturally Occurring Flavonoids as TGF-ß Inhibitors in Breast Cancer: Insights from Docking and Molecular Dynamics Simulations and In-vitro Cytotoxicity Study.

Breast cancer is a global health concern, demanding innovative treatments. Targeting the Transforming Growth Factor-beta (TGF-ß) signaling pathway, pivotal in breast cancer, is a promising approach. TGF-ß inhibits proliferation via G1 phase cell cycle arrest, acting as a suppressor initially, but in later stages, it promotes progression by enhancing motility, invasiveness, and metastasis formation. This study explores naturally occurring flavonoids' interactions with TGF-ß. Using molecular docking against the protein's crystal structure (PDB Id: 1PY5), Gossypin showed the highest docking score and underwent molecular dynamics simulation, revealing complex flexibility and explaining how flavonoids impede TGF-ß signaling in breast cancer. ADMET predictions adhered to Lipinski's rule of Five. Insights into flavonoid-TGF-ß binding offer a novel angle for breast cancer treatment. Flavonoids having a good docking score like gossypin, morin, luteolin and taxifolin shown potent cytotoxic effect on breast cancer cell line, MCF-7. Understanding these interactions could inspire flavonoid-based therapies targeting TGF-ß to halt breast cancer growth. These findings pave the way for personalized, targeted breast cancer therapies, offering hope against this formidable disease.

Prevalence of Cardiovascular Disease and Risk Factors Among Former National Football League Players.

BACKGROUND: Cardiovascular disease (CVD) is the leading cause of death worldwide, but prevalence estimates in former professional athletes are limited. OBJECTIVES: HUDDLE (Heart Health: Understanding and Diagnosing Disease by Leveraging Echocardiograms) aimed to raise awareness and estimate the prevalence of CVD and associated risk factors among members of the National Football League (NFL) Alumni Association and their families through education and screening events. METHODS: HUDDLE was a multicity, cross-sectional study of NFL alumni and family members aged 50 years and older. Subjects reported their health history and participated in CVD education and screening (blood pressure, electrocardiogram, and transthoracic echocardiogram [TTE] assessments). Phone follow-up by investigators occurred 30 days postscreening to review results and recommendations. This analysis focuses on former NFL athletes. RESULTS: Of 498 participants screened, 57.2% (N = 285) were former NFL players, the majority of whom were African American (67.6%). The prevalence of hypertension among NFL alumni was estimated to be 89.8%, though only 37.5% reported a history of hypertension. Of 285 evaluable participants, 61.8% had structural cardiac abnormalities by TTE. Multivariable analysis showed that hypertension was a significant predictor of clinically relevant structural abnormalities on TTE. CONCLUSIONS: HUDDLE identified a large discrepancy between participant self-awareness and actual prevalence of CVD and risk factors, highlighting a significant opportunity for population health interventions. Structural cardiac abnormalities were observed in most participants and were independently predicted by hypertension, affirming the role of TTE for CVD screening in this population aged older than 50 years. (Heart Health: Understanding and Diagnosing Disease by Leveraging Echocardiograms [HUDDLE]; NCT05009589).

Nanomaterials as drug delivery agents for overcoming the blood-brain barrier: A comprehensive review.

Background and Purpose: The blood-brain barrier (BBB), a critical interface of specialized endothelial cells, plays a pivotal role in regulating molecular and ion transport between the central nervous system (CNS) and systemic circulation. Experimental Approach: This review aims to delve into the intricate architecture and functions of the BBB while addressing challenges associated with delivering therapeutics to the brain. Historical milestones and contemporary insights underscore the BBB's significance in protecting the CNS. Key Results: Innovative approaches for enhanced drug transport include intranasal delivery exploiting olfactory and trigeminal pathways, as well as techniques like temporary BBB opening through chemicals, receptors, or focused ultrasound. These avenues hold the potential to reshape conventional drug delivery paradigms and address the limitations posed by the BBB's selectivity. Conclusion: This review underscores the vital role of the BBB in maintaining CNS health and emphasizes the importance of effective drug delivery through this barrier. Nanoparticles emerge as promising candidates to overcome BBB limitations and potentially revolutionize the treatment of CNS disorders. As research progresses, the application of nanomaterials shows immense potential for advancing neurological therapeutics, albeit with careful consideration of safety aspects.

Occupation, Retirement Age, and 20-Year Cognitive Decline: The Atherosclerosis Risk in Communities Neurocognitive Study.

INTRODUCTION: We examined the association of both midlife occupation and age at retirement with cognitive decline in the Atherosclerosis Risk in Communities (ARIC) biracial community-based cohort. METHODS: Current or most recent occupation at ARIC baseline (1987-89; ages 45-64y) was categorized based on 1980 US census major occupation groups and tertiles of the Nam-Powers-Boyd occupational status score (n=14,090). Retirement status via annual follow-up questionnaires administered ascertained in 1999-2007 was classified as occurring before or after age 70 (n=7,503). Generalized estimating equation models were used to examine associations of occupation and age at retirement with trajectories of global cognitive factor scores, assessed from visit 2 (1990-92) to visit 5 (2011-2013). Models were a priori stratified by race and sex and adjusted for demographics and comorbidities. RESULTS: Low occupational status and blue-collar occupations were associated with low baseline cognitive scores in all race-sex strata. Low occupational status and homemaker status were associated with faster decline in White women but slower decline in Black women compared to high occupational status. Retirement before age 70 was associated with slower cognitive decline in White men and women and in Black men. Results did not change substantially after accounting for attrition. CONCLUSION: Low occupational status was associated with cognitive decline in women but not in men. Earlier retirement was associated with a slower cognitive decline in White participants and in Black men. Further research should explore reasons for the observed associations and race-sex differences.

A Review on the Development of Novel Heterocycles as α-Glucosidase Inhibitors for the Treatment of Type-2 Diabetes Mellitus.

One of the most effective therapeutic decencies in the treatment of Type 2 Diabetes Mellitus is the inhibition of α-glucosidase enzyme, which is present at the brush border of the intestine and plays an important role in carbohydrate digestion to form mono-, di-, and polysaccharides. Acarbose, Voglibose, Miglitol, and Erniglitate have been well-known α-glucosidase inhibitors in science since 1990. However, the long synthetic route and side effects of these inhibitors forced the researchers to move their focus to innovate simple and small heterocyclic scaffolds that work as excellent α-glucosidase inhibitors. Moreover, they are also effective against the postprandial hyperglycemic condition in Type 2 Diabetes Mellitus. In this aspect, this review summarizes recent progress in the discovery and development of heterocyclic molecules that have been appraised to show outstanding inhibition of α-glucosidase to yield positive effects against diabetes.

Associations between the EQ-5D-5L and exacerbations of chronic obstructive pulmonary disease in the ETHOS trial.

PURPOSE: Exacerbations of chronic obstructive pulmonary disease (COPD) are associated with deteriorating health and health-related quality of life (HRQoL) among people with COPD during and after events. HRQoL data are key to evaluating treatment cost-effectiveness and informing reimbursement decisions in COPD. EuroQoL 5-dimension 5-level (EQ-5D-5L) utility scores, based on various HRQoL measures, are used in economic evaluations of pharmacotherapy. These analyses estimated associations between EQ-5D-5L utility scores and exacerbations (new and previous) in patients with moderate-to-very severe COPD. METHODS: Longitudinal mixed models for repeated measures (MMRM), adjusted for time and treatment, were conducted using data from the ETHOS study (NCT02465567); models regressed EQ-5D-5L on current and past exacerbations that occurred during the study, adjusting for other patient reported outcomes and clinical factors. RESULTS: Based on the simplest covariate adjusted model (adjusted for current exacerbations and number of previous exacerbations during the study), a current moderate exacerbation was associated with an EQ-5D-5L disutility of 0.055 (95% confidence interval: 0.048, 0.062) with an additional disutility of 0.035 (0.014, 0.055) if the exacerbation was severe. After resolving, each prior exacerbation was associated with a disutility that persisted for the remainder of the study (moderate exacerbation, 0.014 [0.011, 0.016]; further disutility for severe exacerbation, 0.011 [0.003, 0.018]). CONCLUSION: An EQ-5D-5L disutility of 0.090 was associated with a current severe exacerbation in ETHOS. Our findings suggest incorporating the effects of current, recently resolved, and cumulative exacerbations into economic models when estimating benefits and costs of COPD pharmacotherapy, as exacerbations have both acute and persistent effects.

Patient Satisfaction with Oral Testosterone Undecanoate in Men Who Received Prior Testosterone Therapy: An Open-Label, Single-Center Clinical Trial.

PURPOSE: To evaluate patient satisfaction and symptom control in hypogonadal men transitioning from other testosterone therapies to oral testosterone undecanoate (TU). MATERIALS AND METHODS: In this open-label clinical trial, men aged 18 to 75 years with hypogonadism were switched to oral TU after a sufficient washout of previous testosterone therapies. Treatment satisfaction and symptom control were primarily measured using the 9-item Treatment Satisfaction Questionnaire for Medication (TSQM-9) and quantitative androgen deficiency in aging males (qADAM) questionnaires, respectively. Secondary outcomes included changes in serum testosterone (T), estradiol (E2), hematocrit (HCT), and prostate-specific antigen (PSA) levels. RESULTS: Forty-one men participated, with significant improvements in all TSQM-9 scores observed over 6 months. Symptom control as measured by qADAM remained consistent. There was a significant increase in serum T and E2 levels, but HCT and PSA levels remained stable. CONCLUSIONS: Switching to oral TU from other testosterone therapies is associated with increased patient satisfaction and stable hypogonadal symptom control.

Investigating the Antioxidant Capacity of Newly Synthesized Flavonoids via DPPH Assay.

BACKGROUND: Numerous naturally occurring and artificially synthesized flavonoids have garnered attention for their impressive ability to combat oxidative stress and scavenge free radicals when evaluated in laboratory settings. The core aim of our investigation revolved around assessing the antioxidant potential of a diverse range of synthesized flavonoids through in vitro experiments. METHOD: We crafted 29 distinct flavonoids using the aldol condensation mechanism via a chalcone intermediate to accomplish this. We meticulously characterized these newly formed compounds using a variety of spectroscopic techniques. We employed the widely recognized DPPH free radical method for the crucial antioxidant evaluation, a benchmark in such studies Result: The radical scavenging efficacy of our synthesized flavonoids was then meticulously compared to that of the positive control, ascorbic acid, renowned for its antioxidant prowess, and the IC50 values for each compound were calculated and examined. Surprisingly, our results showed that the flavonoids we tested had a wide range of antioxidant activity, with IC50 values that ranged from 75.8 ± 8.30 to 397 ± 25.10 µg/mL. CONCLUSION: Intriguingly, compounds US5, US13, US16, US17, US18, and US21 outshone even ascorbic acid in their antioxidant potential, displaying remarkable scavenging abilities against free radicals. This discovery holds promise for further exploration of these compounds as potential antioxidants with potential applications in health and wellness.

The role of SPP/SPPL intramembrane proteases in membrane protein homeostasis.

Signal peptide peptidase (SPP) and the four SPP-like proteases SPPL2a, SPPL2b, SPPL2c and SPPL3 constitute a family of aspartyl intramembrane proteases with homology to presenilins. The different members reside in distinct cellular localisations within the secretory pathway and the endo-lysosomal system. Despite individual cleavage characteristics, they all cleave single-span transmembrane proteins with a type II orientation exhibiting a cytosolic N-terminus. Though the identification of substrates is not complete, SPP/SPPL-mediated proteolysis appears to be rather selective. Therefore, according to our current understanding cleavage by SPP/SPPL proteases rather seems to serve a regulatory function than being a bulk proteolytic pathway. In the present review, we will summarise our state of knowledge on SPP/SPPL proteases and in particular highlight recently identified substrates and the functional and/or (patho)-physiological implications of these cleavage events. Based on this, we aim to provide an overview of the current open questions in the field. These are connected to the regulation of these proteases at the cellular level but also in context of disease and patho-physiological processes. Furthermore, the interplay with other proteostatic systems capable of degrading membrane proteins is beginning to emerge.

Patient sex, racial and ethnic disparities in emergency department triage: A multi-site retrospective study.

OBJECTIVES: There is limited evidence on sex, racial, and ethnic disparities in Emergency Department (ED) triage across diverse settings. We evaluated differences in the assignment of Emergency Severity Index (ESI) by patient sex and race/ethnicity, accounting for age, clinical factors, and ED operating conditions. METHODS: We conducted a multi-site retrospective study of adult patients presenting to high-volume EDs from January 2019-February 2020. Patient-level data were obtained and analyzed from three EDs (academic, metropolitan community, and rural community) affiliated with a large health system in the Southeastern United States. For the study outcome, ESI levels were grouped into three categories: 1-2 (highest acuity), 3, and 4-5 (lowest acuity). Multinomial logistic regression was used to compare ESI categories by patient race/ethnicity and sex jointly (referent = White males), adjusted for patient age, insurance status, ED arrival mode, chief complaint category, comorbidity score, time of day, day of week, and average ED wait time. RESULTS: We identified 186,840 eligible ED visits with 56,417 from the academic ED, 69,698 from the metropolitan community ED, and 60,725 from the rural community ED. Patient cohorts between EDs varied by patient age, race/ethnicity, and insurance status. The majority of patients were assigned ESI 3 in the academic and metropolitan community EDs (61% and 62%, respectively) whereas 47% were assigned ESI 3 in the rural community ED. In adjusted analyses, White females were less likely to be assigned ESI 1-2 compared to White males although both groups were roughly comparable in the assignment of ESI 4-5. Non-White and Hispanic females were generally least likely to be assigned ESI 1-2 in all EDs. Interactions between ED wait time and race/ethnicity-sex were not statistically significant. CONCLUSIONS: This retrospective study of adult ED patients revealed sex and race/ethnicity-based differences in ESI assignment, after accounting for age, clinical factors, and ED operating conditions. These disparities persisted across three different large EDs, highlighting the need for ongoing research to address inequities in ED triage decision-making and associated patient-centered outcomes.

Right and left ventricular cardiac magnetic resonance imaging derived peak systolic strain is abnormal in children with myocarditis.

PURPOSE: Cardiac Magnetic resonance (CMR) derived left ventricular longitudinal and circumferential strain is known to be abnormal in myocarditis. CMR strain is a useful additional tool that can identify subclinical myocardial involvement and may help with longitudinal follow-up. Right ventricular strain derived by CMR in children has not been studied. We sought to evaluate CMR derived biventricular strain in children with acute myocarditis. METHODS: Children with acute myocarditis who underwent CMR between 2016-2022 at our center were reviewed, this group included subjects with COVID-19 myocarditis. Children with no evidence of myocarditis served as controls Those with congenital heart disease and technically limited images for CMR strain analysis were excluded from final analysis. Biventricular longitudinal, circumferential, and radial peak systolic strains were derived using circle cvi42®. Data between cases and controls were compared using an independent sample t-test. One-way ANOVA with post hoc analysis was used to compare COVID-19, non-COVID myocarditis and controls. RESULTS: 38 myocarditis and 14 controls met inclusion criteria (mean age 14.4 ± 3 years). All CMR derived peak strain values except for RV longitudinal strain were abnormal in myocarditis group. One-way ANOVA revealed that there was a statistically significant difference with abnormal RV and LV strain in COVID-19 myocarditis when compared to non-COVID-19 myocarditis and controls. CONCLUSION: CMR derived right and left ventricular peak systolic strain using traditionally acquired cine images were abnormal in children with acute myocarditis. All strain measurements were significantly abnormal in children with COVID-19 even when compared to non-COVID myocarditis.

Emerging green synthetic routes for thiazole and its derivatives: Current perspectives.

This review article provides an overview of the green synthesis of thiazole derivatives, emphasizing sustainable and environmentally friendly methodologies. Thiazole derivatives possess significant value and find diverse applications across various fields. However, conventional synthesis methods often involve hazardous reagents and generate substantial waste, posing environmental concerns. The green synthesis of thiazole derivatives employs renewable starting materials, nontoxic catalysts, and mild reaction conditions to minimize environmental impact. Innovative techniques such as microwave irradiation, ultrasound synthesis, green solvents, a green catalyst-based approach, and mechanochemistry-mediated synthesis are employed, offering advantages in terms of scalability, cost-effectiveness, and purification simplicity. The resulting thiazole derivatives exhibit comparable or enhanced biological activities, showcasing the feasibility and practicality of green synthesis in drug discovery. This review paper underscores the importance of sustainable approaches in functional molecular synthesis and encourages further research in this domain.

In-Hospital Code Status Updates: Trends Over Time and the Impact of COVID-19.

OBJECTIVE: The primary objective was to evaluate if the percentage of patients with missing or inaccurate code status documentation at a Trauma Level 1 hospital could be reduced through daily updates. The secondary objective was to examine if patient preferences for DNR changed during the COVID-19 pandemic. METHODS: This retrospective study, spanning March 2019 to December 2022, compared the code status in ICU and ED patients drawn from two data sets. The first was based on historical electronic medical records (EHR), and the second involved daily updates of code status following patient admission. RESULTS: Implementing daily updates upon admission was more effective in ICUs than in the ED in reducing missing code status documentation. Around 20% of patients without a specific code status chose DNR under the new system. During COVID-19, a decrease in ICU patients choosing DNR and an increase in full code (FC) choices were observed. CONCLUSION: This study highlights the importance of regular updates and discussions regarding code status to enhance patient care and resource allocation in ICU and ED settings. The COVID-19 pandemic's influence on shifting patient preferences towards full code status underscores the need for adaptable documentation practices. Emphasizing patient education about DNR implications and benefits is key to supporting informed decisions that reflect individual health contexts and values. This approach will help balance the considerations for DNR and full code choices, especially during health care crises.

Effectiveness of a Novel Rapid Infusion Device and Clinician Education for Early Fluid Therapy by Emergency Medical Services in Sepsis Patients: A Pre-Post Observational Study.

OBJECTIVE: Emergency medical services (EMS) clinicians are tasked with early fluid resuscitation for patients with sepsis. Traditional methods for prehospital fluid delivery are limited in speed and ease-of-use. We conducted a comparative effectiveness study of a novel rapid infusion device for prehospital fluid delivery in suspected sepsis patients. METHODS: This pre-post observational study evaluated a hand-operated, rapid infusion device in a single large EMS system from July 2021-July 2022. Prior to device deployment, EMS clinicians completed didactic and simulation-based device training. Data were extracted from the EMS electronic health record. Eligible patients included adults with suspected sepsis treated by EMS with intravenous fluids. The primary outcome was the proportion of patients receiving goal fluid volume (at least 500 mL) prior to hospital arrival. Secondary outcomes included in-hospital mortality, disposition, and length of stay. Multivariable logistic regression was used to compare outcomes between 6-month pre- and post-implementation periods (July-December 2021 and February-July 2022, respectively), adjusting for patient demographics, abnormal prehospital vital signs, and EMS transport interval. RESULTS: Of 1,180 eligible patients (552 in the pre-implementation period; 628 in the post-implementation period), the mean age was 72 years old, 45% were female, and 25% were minority race-ethnicity. Median (interquartile range) fluid volume (in mL) increased between the pre- and post-implementation periods (600 [400,1,000] and 850 [500-1,000], respectively). Goal fluid volume was achieved in 70% of pre-implementation patients and 82% of post-implementation patients. In adjusted analysis, post-implementation patients were significantly more likely to receive goal fluid volume than pre-implementation patients (adjusted odds ratio (aOR) 2.00, 95% confidence interval (CI) 1.51-2.66). Pre-post in-hospital mortality was not significantly different (aOR 0.91, 95% CI 0.59-1.39). CONCLUSION: In a single EMS system, sepsis education and introduction of a rapid infusion device was associated with achieving goal fluid volume for suspected sepsis. Further research is needed to assess the clinical effectiveness of infusion device implementation to improve sepsis patient outcomes.

Community Socioeconomic and Urban-Rural Disparities in Prehospital Notification of Stroke by Emergency Medical Services in North Carolina.

OBJECTIVES: Notification by emergency medical services (EMS) to the destination hospital of an incoming suspected stroke patient is associated with timelier in-hospital evaluation and treatment. Current data on adherence to this evidence-based best practice are limited, however. We examined the frequency of EMS stroke prenotification in North Carolina by community socioeconomic status (SES) and rurality. METHODS: Using a statewide database of EMS patient care reports, we selected 9-1-1 responses in 2019 with an EMS provider impression of stroke or documented stroke care protocol use. Eligible patients were 18 years old and older with a completed prehospital stroke screen. Incident street addresses were geocoded to North Carolina census tracts and linked to American Community Survey socioeconomic data and urban-rural commuting area codes. High, medium, and low SES tracts were defined by SES index tertiles. Tracts were classified as urban, suburban, and rural. We used multivariable logistic regression to estimate independent associations between tract-level SES and rurality with EMS prenotification, adjusting for patient age, sex, and race/ethnicity; duration of symptoms; incident day of week and time of day; 9-1-1 dispatch complaint; EMS provider primary impression; and prehospital stroke screen interpretation. RESULTS: The cohort of 9527 eligible incidents was mostly at least 65 years old (65%), female (55%), and non-Hispanic White (71%). EMS prenotification occurred in 2783 (29%) patients. Prenotification in low SES tracts (27%) occurred less often than in medium (30%) and high (32%) SES tracts. Rural tracts had the lowest frequency (21%) compared with suburban (28%) and urban (31%) tracts. In adjusted analyses, EMS prenotification was less likely in low SES (vs high SES; odds ratio 0.76, 95% confidence interval 0.67-0.88) and rural (vs urban; odds ratio 0.64, 95% confidence interval 0.52-0.77) tracts. CONCLUSIONS: Across a large, diverse population, EMS prenotification occurred in only one-third of suspected stroke patients. Furthermore, low SES and rural tracts were independently associated with a lower likelihood of prehospital notification. These findings suggest the need for education and quality improvement initiatives to increase EMS stroke prenotification, particularly in underserved communities.

Dynamic association of the intramembrane proteases SPPL2a/b and their substrates with tetraspanin-enriched microdomains.

Signal peptide peptidase-like 2a and b (SPPL2a/b) are aspartyl intramembrane proteases and cleave tail-anchored proteins as well as N-terminal fragments (NTFs) derived from type II-oriented transmembrane proteins. How these proteases recruit substrates and cleavage is regulated, is still incompletely understood. We found that SPPL2a/b localize to detergent-resistant membrane (DRM) domains with the characteristics of tetraspanin-enriched microdomains (TEMs). Based on this, association with several tetraspanins was evaluated. We demonstrate that not only SPPL2a/b but also their substrates tumor necrosis factor (TNF) and CD74 associate with tetraspanins like CD9, CD81, and CD82 and/or TEMs and analyze the stability of these complexes in different detergents. CD9 and CD81 deficiency has protease- and substrate-selective effects on SPPL2a/b function. Our findings suggest that reciprocal interactions with tetraspanins may assist protease-substrate encounters of SPPL2a/b within the membrane. Beyond SPP/SPPL proteases, this supports previous concepts that tetraspanins facilitate membrane-embedded proteolytic processes.