Human Blood Extracellular Vesicles Activate Transcription of NF-kB-Dependent Genes in A549 Lung Adenocarcinoma Cells.

Extracellular vesicles (EVs) produced by various cell types are heterogeneous in size and composition. Changes in the RNA sets of EVs in biological fluids are considered the basis for the development of new approaches to minimally invasive diagnostics and the therapy of human diseases. In this study, EVs were obtained from the blood of healthy donors by centrifugation, followed by ultracentrifugation. It was shown that EVs consist of several populations including small exosome-like vesicles and larger microvesicle-like particles. The composition of EVs' RNAs was determined. A549 lung adenocarcinoma cells were incubated with EV and the NGS analysis of differentially expressed genes was performed. During the incubation of A549 cells with EVs, the levels of mRNA encoding components for the NF-kB signaling pathway increased, as well as the expression of genes controlled by the NF-kB transcription factor. Overall, our results suggest that components of EVs trigger the NF-kB signaling cascade in A549 cells, leading to the transcription of genes including cytokines, adhesion molecules, cell cycle regulators, and cell survival factors. Our data provide insight into the interaction between blood EVs and human cells and can be used for designing new tools for the diagnosis and treatment of human diseases.

Real-World Application of Pre-Orchiectomy miR-371a-3p Test in Testicular Germ Cell Tumor Management.

PURPOSE: Current serum tumor markers for testicular germ cell tumor are limited by low sensitivity. Growing evidence supports the use of circulating miR-371a-3p as a superior marker for malignant (viable) germ cell tumor management. We evaluated the real-world application of serum miR-371a-3p levels in detecting viable germ cell tumor among patients undergoing partial or radical orchiectomy. MATERIALS AND METHODS: Serum samples were collected from 69 consecutive patients before orchiectomy. Performance characteristics of serum miR-371a-3p were compared with conventional serum tumor markers (⍺-fetoprotein/ß-human chorionic gonadotropin/lactate dehydrogenase) between patients with viable germ cell tumor and those without viable germ cell tumor on orchiectomy pathology. Relative miR-371a-3p levels were correlated with clinical course. The Kruskal-Wallis test and linear and ordinal regression models were used for analysis. RESULTS: For detecting viable germ cell tumor, combined conventional serum tumor markers had a specificity of 100%, sensitivity of 58% and AUC of 0.79. The miR-371a-3p test showed a specificity of 100%, sensitivity of 93% and AUC of 0.978. Median relative expression of miR-371a-3p in viable germ cell tumor cases was more than 6,800-fold higher than in those lacking viable germ cell tumor. miR-371a-3p levels correlated with composite stage (p=0.006) and, among composite stage I cases, independently associated with embryonal carcinoma percentage (p=0.0012) and tumor diameter (p <0.0001). Six patients underwent orchiectomy after chemotherapy and were correctly predicted to have presence or absence of viable germ cell tumor by the miR-371a-3p test. CONCLUSIONS: If validated, the miR-371a-3p test can be used in conjunction with conventional serum tumor markers to aid clinical decision making. A positive miR-371a-3p test in patients after preoperative chemotherapy or with solitary testes could potentially guide subsequent orchiectomy or observation.

Impact of circulating microRNA test (miRNA-371a-3p) on appropriateness of treatment and cost outcomes in patients with Stage I non-seminomatous germ cell tumours.

OBJECTIVES: To determine whether utilisation of a serum microRNA (miRNA) test could improve treatment appropriateness and cost-effectiveness for patients with Stage I non-seminomatous germ cell tumours (NSGCTs). PATIENTS AND METHODS: A decision tree model was built to investigate treatment course, clinical and cost outcomes for patients with Stage IA (T1N0M0S0) and IB (T2-4N0M0S0) NSGCT. The model compared outcomes and cost of standard approach using histopathology, conventional serum tumour markers and radiographic staging (standard model) to a miRNA-based approach using the standard model + post-orchidectomy serum miR-371a-3p (marker model). Probabilities of expected treatment and outcomes were based on presence/absence of cancer upon entering into the model. Overtreatment was defined as adjuvant chemotherapy or primary retroperitoneal lymph node dissection in a patient without cancer. Undertreatment was defined as initial surveillance for a patient with cancer. RESULTS: Utilising the miRNA marker-based approach, 26% of patients avoid overtreatment and 8% avoid undertreatment in Stage IA NSGCT; 27% avoid overtreatment and 23% avoid undertreatment in Stage IB disease. Appropriate treatment decision-making increased from 65% to 94% and 50% to 92% for Stage IA and IB, respectively. The miRNA-based approach remained cost-effective over a wide range of performance characteristics with savings of ~$1400 (American dollars)/patient for both Stage IA and IB disease. CONCLUSION: A miRNA-based approach may potentially select patients with Stage I NSGCT for correct treatment in a cost-effective manner. Identification of residual teratoma-only remains an issue. Prospective studies are necessary to validate these findings.

Analysis of the efficiency of recombinant Escherichia coli strain cultivation in a gas-vortex bioreactor.

The levels of aeration and mass transfer are critical parameters required for an efficient aerobic bioprocess, and directly depend on the design features of exploited bioreactors. A novel apparatus, using gas vortex for aeration and mass transfer processes, was constructed in the Center of Vortex Technologies (Novosibirsk, Russia). In this paper, we compared the efficiency of recombinant Escherichia coli strain cultivation using novel gas-vortex technology with conventional bioprocess technologies such as shake flasks and bioreactors with mechanical stirrers. We demonstrated that the system of aeration and agitation used in gas-vortex bioreactors provides 3.6 times higher volumetric oxygen transfer coefficient in comparison with mechanical bioreactor. The use of gas-vortex bioreactor for recombinant E. coli strain cultivation allows to increase the efficiency of target protein expression at 2.2 times for BL21(DE3)/pFK2 strain and at 3.5 times for auxotrophic C600/pRT strain (in comparison with stirred bioreactor).

Vesicular and Extra-Vesicular RNAs of Human Blood Plasma.

Human blood contains a great variety of membrane-covered RNA carrying vesicles which are spherical or tubular particles enclosed by a phospholipid bilayer. Circulating vesicles are thought to mediate cell-to-cell communication and their RNA cargo can act as regulatory molecules. In this work, we separated blood plasma of healthy donors by centrifugation and determined that vesicles precipitated at 16,000 g were enriched with CD41a, marker of platelets. At 160,000 g, the pellets were enriched with CD3 marker of T cells. To characterize the RNA-content of the blood plasma sub fractions, we performed high throughput sequencing of the RNA pelleted within vesicles at 16,000 g and 160,000 g as well as RNA remaining in the vesicle-free supernatant. We found that blood plasma sub fractions contain not only extensive set of microRNAs but also fragments of other cellular RNAs: rRNAs, tRNAs, mRNAs, lncRNAs, small RNAs including RNAs encoded by mtDNAs. Our data indicate that a variety of blood plasma RNAs circulating within vesicles as well as of extra-vesicular RNAs are comparable to the variety of cellular RNA species.

An overview of Brevinin superfamily: structure, function and clinical perspectives.

Antimicrobial peptides are the backbone of first-line defense against various microorganisms in the animal kingdom. Thus, not surprisingly, they are gaining attention in the science and medical fields as a rich repository of new pro-drugs. Below, we focus our attention on the Brevinin family of anuran peptides. While most of them show strong antibacterial activities, some, e.g. Brevinin-2R, appear to be promising anticancer molecules, exhibiting better a therapeutic window than widely-use anticancer drugs like doxorubicin. We briefly introduce the field, followed by highlighting the promising therapeutic properties of Brevinins. Next, we provide information about the cloning and phylogenetic aspects of Brevinin genes. In the final paragraphs of this chapter, we discuss possible large-scale production methods of Brevinins, giving examples of some systems that are already in use. Towards the end, we discuss various means of modification of biologic properties of Brevinins, either by chemical modifications or by amino acid substitution and sequence rearrangements. In this context, also other unique properties of Brevinins are briefly mentioned. Finally, we discuss the future of the Brevinin field, particularly highlighting yet to be answered biologic questions, like for example presumed anti-viral and antitumor activities of Brevinin family members.

Seminoma subtypes differ in the organization and functional state of the immune microenvironment.

Seminoma is the most common type of testicular germ cell tumors (TGCTs) among 15-44 years old men. Seminoma treatments include orchiectomy, platinum-based chemotherapy and radiotherapy. These radical treatment methods cause up to 40 severe adverse long-term side effects including secondary cancers. Immunotherapy based on immune checkpoint inhibitors, which showed its efficiency for many types of cancer, can be important alternative to the platinum-based therapy for seminoma patients. However, five independent clinical trials evaluating the efficiency of immune checkpoint inhibitors for TGCTs treatment were shut down at the phase II due to lacking clinical efficacy and detailed mechanisms of this phenomena are yet to be discovered. Recently we identified two distinct seminoma subtypes based on transcriptomic data and here we focused on the analysis of seminoma microenvironment and its subtype-specific characteristics. Our analysis revealed that less differentiated subtype 1 of seminoma has immune microenvironment with significantly lower immune score and larger fraction of neutrophils. Both are features of the immune microenvironment at an early developmental stage. On the contrary, subtype 2 seminoma is characterized by the higher immune score and overexpression of 21 genes related to senescence-associated secretory phenotype. Seminoma single cell transcriptomic data showed that 9 out of 21 genes are predominantly expressed in immune cells. Therefore, we hypothesized that senescence of immune microenvironment can be one of the reasons for seminoma immunotherapy failure. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03530-1.

Electrotaxis evokes directional separation of co-cultured keratinocytes and fibroblasts.

Bioelectric communication plays a significant role in several cellular processes and biological mechanisms, such as division, differentiation, migration, cancer metastasis, and wound healing. Ion flow across cellular walls leads to potential gradients and subsequent formation of constant or time-varying electric fields(EFs), which regulate cellular processes. An EF is natively generated towards the wound center during epithelial wound healing, aiming to align and guide cell migration, particularly of macrophages, fibroblasts, and keratinocytes. While this phenomenon, known as electrotaxis or galvanotaxis, has been extensively investigated across many cell types, it is typically explored one cell type at a time, which does not accurately represent cellular interactions during complex biological processes. Here we show the co-cultured electrotaxis of epidermal keratinocytes and dermal fibroblasts with a salt-bridgeless microfluidic approach for the first time. The electrotactic response of these cells was first assessed in mono-culture to establish a baseline, resulting in the characteristic cathodic migration for keratinocytes and anodic for fibroblasts. Both cell types retained their electrotactic properties in co-culture leading to clear cellular partition even in the presence of cellular collisions. The methods leveraged here pave the way for future co-culture electrotaxis experiments where the concurrent influence of cell types can be thoroughly investigated.

Bioelectronic microfluidic wound healing: a platform for investigating direct current stimulation of injured cell collectives.

Upon cutaneous injury, the human body naturally forms an electric field (EF) that acts as a guidance cue for relevant cellular and tissue repair and reorganization. However, the direct current (DC) flow imparted by this EF can be impacted by a variety of diseases. This work delves into the impact of DC stimulation on both healthy and diabetic in vitro wound healing models of human keratinocytes, the most prevalent cell type of the skin. The culmination of non-metal electrode materials and prudent microfluidic design allowed us to create a compact bioelectronic platform to study the effects of different sustained (12 hours galvanostatic DC) EF configurations on wound closure dynamics. Specifically, we compared if electrotactically closing a wound's gap from one wound edge (i.e., uni-directional EF) is as effective as compared to alternatingly polarizing both the wound's edges (i.e., pseudo-converging EF) as both of these spatial stimulation strategies are fundamental to the eventual translational electrode design and strategy. We found that uni-directional electric guidance cues were superior in group keratinocyte healing dynamics by enhancing the wound closure rate nearly three-fold for both healthy and diabetic-like keratinocyte collectives, compared to their non-stimulated respective controls. The motility-inhibited and diabetic-like keratinocytes regained wound closure rates with uni-directional electrical stimulation (increase from 1.0 to 2.8% h-1) comparable to their healthy non-stimulated keratinocyte counterparts (3.5% h-1). Our results bring hope that electrical stimulation delivered in a controlled manner can be a viable pathway to accelerate wound repair, and also by providing a baseline for other researchers trying to find an optimal electrode blueprint for in vivo DC stimulation.

Evaluation of miR-371a-3p to predict viable germ cell tumor in patients with pure seminoma receiving retroperitoneal lymph node dissection.

INTRODUCTION AND OBJECTIVE: Conventional serum tumor markers (STMs) for testicular germ cell tumors (GCTs) offer limited performance with particularly poor sensitivity in cases of minimal residual disease and pure seminoma. While growing evidence has indicated miR-371a-3p to be a superior biomarker, its utility in detecting pure seminoma at recurrence has not been extensively explored. This study's objective was to explore miR-371a-3p's utility in detecting metastatic pure seminoma at retroperitoneal lymph node dissection (RPLND). METHODS: RNA was isolated from patient serum samples collected pre-RPLND. Fifteen patients were assigned to our 'benign' (n = 6) or 'seminoma' (n = 9) group based on pathological confirmation of viable seminoma. Five of the patients received chemotherapy before RPLND (PC-RPLND), and 10 were chemotherapy naïve. MiR-371a-3p expression was quantified via RT-quantitative polymerase chain reaction. The Cq values were statistically evaluated to obtain performance measurements. RESULTS: Median relative expression of miR-371a-3p was higher in the Seminoma group than the Benign, but this difference was not statistically significant (Rq = 3705 and 241, respectively, p = 0.2844). Of the 10 chemotherapy naïve patients, nine had viable seminoma at RPLND, and seven had elevated miR-371a-3p expression. Among the five postchemotherapy (PC) patients, zero had viable GCT at RPLND, and two had elevated miR-371a-3p expression. The primary RPLND group presented 78% sensitivity and 100% specificity. Specificity in the PC-RPLND group was 60%. An optimal Rq threshold of 28.62 was determined by Youden's J statistic, yielding 78% sensitivity and 67% specificity. Receiver operating characteristic analysis provided an AUC of 0.704 (95% CI: 0.43-0.98, p = 0.1949). Despite modest performance, miR-371a-3p exhibited improved sensitivity and specificity compared with conventional STMs. CONCLUSIONS: MiR-371a-3p outperformed STMs in the primary RPLND settings. However, miR-371a-3p was not a robust predictor of pathology in the PC setting. These results suggest that pure seminoma at RPLND is a clinical context, wherein the miRNA assay may require further refinement.

Refining the serum miR-371a-3p test for viable germ cell tumor detection: identification and definition of an indeterminate range.

Circulating miR-371a-3p has excellent performance in the detection of viable (non-teratoma) GCT pre-orchiectomy; however, its ability to detect occult disease is understudied. To refine the serum miR-371a-3p assay in the minimal residual disease setting we compared performance of raw (Cq) and normalized (∆Cq, RQ) values from prior assays, and validated interlaboratory concordance by aliquot swapping. Revised assay performance was determined in a cohort of 32 patients suspected of occult retroperitoneal disease. Assay superiority was determined by comparing resulting receiver-operator characteristic (ROC) curves using the Delong method. Pairwise t-tests were used to test for interlaboratory concordance. Performance was comparable when thresholding based on raw Cq vs. normalized values. Interlaboratory concordance of miR-371a-3p was high, but reference genes miR-30b-5p and cel-miR-39-3p were discordant. Introduction of an indeterminate range of Cq 28-35 with a repeat run for any indeterminate improved assay accuracy from 0.84 to 0.92 in a group of patients suspected of occult GCT. We recommend that serum miR-371a-3p test protocols are updated to a) utilize threshold-based approaches using raw Cq values, b) continue to include an endogenous (e.g., miR-30b-5p) and exogenous non-human spike-in (e.g., cel-miR-39-3p) microRNA for quality control, and c) to re-run any sample with an indeterminate result.

Refining the serum miR-371a-3p test for viable germ cell tumor detection.

Circulating miR-371a-3p has excellent performance in the detection of viable (non-teratoma) germ cell tumor (GCT) pre-orchiectomy; however, its ability to detect occult disease is understudied. To refine the serum miR-371a-3p assay in the minimal residual disease setting we compared performance of raw (Cq) and normalized (∆Cq, RQ) values from prior assays, and validated interlaboratory concordance by aliquot swapping. Revised assay performance was determined in a cohort of 32 patients suspected of occult retroperitoneal disease. Assay superiority was determined by comparing resulting receiver-operator characteristic (ROC) curves using the Delong method. Pairwise t-tests were used to test for interlaboratory concordance. Performance was comparable when thresholding based on raw Cq vs. normalized values. Interlaboratory concordance of miR-371a-3p was high, but reference genes miR-30b-5p and cel-miR-39-3p were discordant. Introduction of an indeterminate range of Cq 28-35 with a repeat run for any indeterminate improved assay accuracy from 0.84 to 0.92 in a group of patients suspected of occult GCT. We recommend that serum miR-371a-3p test protocols are updated to (a) utilize threshold-based approaches using raw Cq values, (b) continue to include an endogenous (e.g., miR-30b-5p) and exogenous non-human spike-in (e.g., cel-miR-39-3p) microRNA for quality control, and (c) to re-run any sample with an indeterminate result.

Integrated Molecular Analysis Reveals 2 Distinct Subtypes of Pure Seminoma of the Testis.

Objective: Testicular germ cell tumors (TGCT) are the most common solid malignancy in adolescent and young men, with a rising incidence over the past 20 years. Overall, TGCTs are second in terms of the average life years lost per person dying of cancer, and clinical therapeutics without adverse long-term side effects are lacking. Platinum-based regimens for TGCTs have heterogeneous outcomes even within the same histotype that frequently leads to under- and over-treatment. Understanding of molecular differences that lead to diverse outcomes of TGCT patients may improve current treatment approaches. Seminoma is the most common subtype of TGCTs, which can either be pure or present in combination with other histotypes. Methods: Here we conducted a computational study of 64 pure seminoma samples from The Cancer Genome Atlas, applied consensus clustering approach to their transcriptomic data and revealed 2 clinically relevant seminoma subtypes: seminoma subtype 1 and 2. Results: Our analysis identified significant differences in pluripotency stage, activity of double stranded DNA breaks repair mechanisms, rates of loss of heterozygosity, and expression of lncRNA responsible for cisplatin resistance between the subtypes. Seminoma subtype 1 is characterized by higher pluripotency state, while subtype 2 showed attributes of reprograming into non-seminomatous TGCT. The seminoma subtypes we identified may provide a molecular underpinning for variable responses to chemotherapy and radiation. Conclusion: Translating our findings into clinical care may help improve risk stratification of seminoma, decrease overtreatment rates, and increase long-term quality of life for TGCT survivors.

Serum Small RNA Sequencing and miR-375 Assay Do Not Identify the Presence of Pure Teratoma at Postchemotherapy Retroperitoneal Lymph Node Dissection.

Existing tumor markers for testicular germ cell tumor (TGCT) cannot detect the presence of pure teratoma. Serum miRNAs have strong performance detecting other subtypes of TGCT. Previous reports suggest high levels of miR-375 expression in teratoma tissue. The purpose of this study was to explore the role of serum miRNA, including miR-375, in detecting the presence of teratoma at postchemotherapy retroperitoneal lymph node dissection (PC-RPLND). We prospectively collected presurgical serum from 40 TGCT patients undergoing PC-RPLND (21 with teratoma at RPLND and 19 with no evidence of disease). We examined the utility of serum miR-375-3p and miR-375-5p by quantitative polymerase chain reaction, and searched for other putative serum miRNAs with small RNA sequencing. The area under the receiver operating characteristic curve (AUC) and univariate analyses were utilized to evaluate test characteristics and predictors of teratoma. Both serum miR-375-3p and miR-375-5p exhibited poor performance (miR-375-3p: 86% sensitivity, 32% specificity, AUC: 0.506; miR-375-5p: 55% sensitivity, 67% specificity, AUC: 0.556). Teratoma at orchiectomy was the only predictor of PC-RPLND teratoma. Small RNA sequencing identified three potentially discriminatory miRNAs, but further validation demonstrated no utility. Our results confirm prior reports that serum miR-375 cannot predict teratoma, and suggest that there may not exist a predictive serum miRNA for teratoma.

Variety of RNAs in Peripheral Blood Cells, Plasma, and Plasma Fractions.

Human peripheral blood contains RNA in cells and in extracellular membrane vesicles, microvesicles and exosomes, as well as in cell-free ribonucleoproteins. Circulating mRNAs and noncoding RNAs, being internalized, possess the ability to modulate vital processes in recipient cells. In this study, with SOLiD sequencing technology, we performed identification, classification, and quantification of RNAs from blood fractions: cells, plasma, plasma vesicles pelleted at 16,000g and 160,000g, and vesicle-depleted plasma supernatant of healthy donors and non-small cell lung cancer (NSCLC) patients. It was determined that 16,000g blood plasma vesicles were enriched with cell-free mitochondria and with a set of mitochondrial RNAs. The variable RNA set of blood plasma 160,000g pellets reflected the prominent contribution of U1, U5, and U6 small nuclear RNAs' fragments and at the same time was characterized by a remarkable depletion of small nucleolar RNAs. Besides microRNAs, the variety of fragments of mRNAs and snoRNAs dominated in the set of circulating RNAs differentially expressed in blood fractions of NSCLC patients. Taken together, our data emphasize that not only extracellular microRNAs but also circulating fragments of messenger and small nuclear/nucleolar RNAs represent prominent classes of circulating regulatory ncRNAs as well as promising circulating biomarkers for the development of disease diagnostic approaches.

Selection of antitumor displayed peptides for the specific delivery of the anticancer drug lactaptin.

It has been previously demonstrated that lactaptin, the proteolytic fragment of human milk protein κ-casein, induces the death of various cultured cancer cells. The recombinant analog of lactaptin, RL2, effectively induces the apoptosis of mouse hepatocarcinoma-1 (HA-1) tumor cells in vitro and suppress the growth of HA-1 tumors and metastases in vivo. The antitumor drug Lactaptin developed on the basis of RL2 has been successful in preclinical trials. Lactaptin shows its efficiency in relation to mouse and human cancer cells and tumors. However, Lactaptin, as with the majority of protein-based therapeutic drugs, is distributed evenly throughout the organism, which reduces its antitumor efficacy. To develop the targeted delivery of lactaptin, the present study selected tumor-specific peptides by screening a phage display peptide library in vivo on A/Sn strain mice with subcutaneously transplanted HA-1 cells. Two genetic constructs were made for the production of recombinant fusion proteins composed of RL2 and the selected tumor-targeting peptide. In vitro experiments involving HA-1, MDA-MB-231 and MCF-7 cells cultures demonstrated that the fusion proteins induce apoptotic death in mouse and human tumor cells, as with RL2. The in vivo experiments involving the mouse HA-1 tumor model demonstrated that the tumor fluorescence intensity of the Cy5-fusion protein conjugates is higher than that of RL2-Cy5. As conjugation of the tumor-specific peptides to RL2 provided retention of RL2 in the tumor tissues, fusion proteins composed of lactaptin and peptides specific for human tumors are deemed promising to improve the antitumor efficiency of lactaptin.

Artificial box C/D RNAs affect pre-mRNA maturation in human cells.

Box C/D small nucleolar RNAs (snoRNAs) are known to guide the 2'-O-ribose methylation of nucleotides in eukaryotic ribosomal RNAs and small nuclear RNAs. Recently snoRNAs are predicted to regulate posttranscriptional modifications of pre-mRNA. To expand understanding of the role of snoRNAs in control of gene expression, in this study we tested the ability of artificial box C/D RNAs to affect the maturation of target pre-mRNA. We found that transfection of artificial box C/D snoRNA analogues directed to HSPA8 pre-mRNAs into human cells induced suppression of the target mRNA expression in a time- and dose-dependent manner. The artificial box C/D RNA directed to the branch point adenosine of the second intron, as well as the analogue directed to the last nucleotide of the second exon of the HSPA8 pre-mRNA caused the most prominent influence on the level of HSPA8 mRNAs. Neither box D nor the ability to direct 2'-O-methylation of nucleotides in target RNA was essential for the knockdown activity of artificial snoRNAs. Inasmuch as artificial box C/D RNAs decreased viability of transfected human cells, we propose that natural snoRNAs as well as their artificial analogues can influence the maturation of complementary pre-mRNA and can be effective regulators of vital cellular processes.

Predictive value of CD4 cell count nadir on long-term mortality in HIV-positive patients in Uganda.

OBJECTIVE: Although international guidelines recommend initiating antiretroviral therapy (ART) when a patient's CD4 cell count is ≤350 cells/µL, most patients in resource-limited settings present with much lower CD4 cell counts. The lowest level that their CD4 cell count reaches, the nadir, may have long-term consequences in terms of mortality. We examined this health state in a large cohort of HIV+ patients in Uganda. DESIGN: This was an observational study of HIV patients in Uganda aged 14 years or older, who were enrolled in 10 major clinics across Uganda. METHODS: We assessed the CD4 nadir of patients, using their CD4 cell count at initiation of ART, stratified into categories (,50, 50-99, 100-149, 150-249, 250+ cells/µL). We constructed Kaplan-Meier curves to assess the differences in survivorship for patients left-censored at 1 year and 2 years after treatment initiation. We used Cox proportional hazards regression to model the associations between CD4 nadir and mortality. We adjusted mortality for loss-to-follow-up. RESULTS: Of 22,315 patients, 20,129 patients had greater than 1 year of treatment follow-up. Among these patients, 327 (1.6%) died and 444 (2.2%) were lost to follow-up. After left-censoring at one year, relative to lowest CD4 strata, patients with higher CD4 counts had significantly lower rates of mortality (CD4 150-249, hazard ratio [HR] 0.60, 95% confidence interval [CI]: 0.45-0.82, P = 0.001; 250+, HR 0.66, 95% CI, 0.44-1.00, P = -0.05). Male sex, older age, and duration of time on ART were independently associated with mortality. When left-censoring at 2 years, CD4 nadir was no longer statistically significantly associated with mortality. CONCLUSION: After surviving for 1 year on ART, a CD4 nadir was strongly predictive of longer-term mortality among patients in Uganda. This should argue for efforts to increase engagement with patients to ensure a higher CD4 nadir at initiation of treatment.