Treponema pallidum-induced prostaglandin E2 secretion in skin fibroblasts leads to neuronal hyperpolarization: A cause of painless ulcers.

BACKGROUND: Primary syphilis is characterized by painless ulcerative lesions in the genitalia, the aetiology of painless remains elusive. OBJECTIVES: To investigate the role of Treponema pallidum in painless ulcer of primary syphilis, and the mechanisms underlying painless ulcers caused by T. pallidum. METHODS: An experimental rabbit model of primary syphilis was established to investigate its effects on peripheral nerve tissues. Human skin fibroblasts were used to examine the role of T. pallidum in modulating neurotransmitters associated with pain and to explore the signalling pathways related to neurotransmitter secretion by T. pallidum in vitro. RESULTS: Treponema pallidum infection did not directly lead to neuronal damage or interfere with the neuronal resting potential. Instead, it facilitated the secretion of prostaglandin E2 (PGE2) through endoplasmic reticulum stress in both rabbit and human skin fibroblasts, and upregulation of PGE2 induced the hyperpolarization of neurones. Moreover, the IRE1α/COX-2 signalling pathway was identified as the underlying mechanism by which T. pallidum induced the production of PGE2 in human skin fibroblasts. CONCLUSION: Treponema pallidum promotes PGE2 secretion in skin fibroblasts, leading to the excitation of neuronal hyperpolarization and potentially contributing to the pathogenesis of painless ulcers in syphilis.

Treponema pallidum protein Tp47 induced prostaglandin E2 to inhibit the phagocytosis in human macrophages.

BACKGROUND: During Treponema pallidum (T. pallidum) infection, the host's immune system actively engages in pursuit and elimination of T. pallidum, while T. pallidum skillfully employs various mechanisms to evade immune recognition. Macrophages exhibit incomplete clearance of T. pallidum in vitro and the underlying mechanism of how T. pallidum resists the attack of macrophage remains unclear. OBJECTIVES: To investigate the effect of T. pallidum membrane protein Tp47 on the phagocytosis of macrophages. METHODS: THP-1-derived macrophages were used to investigate the role of Tp47 in the secretion of Prostaglandin E2 (PGE2) in macrophages and the mechanism by which Tp47 induced the production of PGE2, as well as the impact of PGE2 on the macrophage's phagocytosis. RESULTS: Tp47 (1-10 µg/mL) significantly inhibited the phagocytosis of latex beads and T. pallidum in macrophages (p ≤ 0.05). PGE2 production by macrophages could be induced by Tp47, and the phagocytic function of macrophages could be restored using PGE2 antibody. Tp47 produced PGE2 by activating the PERK/NF-κB/COX-2 pathway in macrophages. Inhibitors targeting PERK, NF-κB and COX-2, respectively, reduced the level of PGE2 and restored the phagocytic function of macrophages. CONCLUSION: Tp47-induced PGE2 production via the PERK/NF-κB/COX-2 pathway contributed to macrophage phagocytosis inhibition, which potentially contributes to immune evasion during the T. pallidum infection.

Recombinant Treponema pallidum protein Tp47 promoted the phagocytosis of macrophages by activating NLRP3 inflammasome induced by PKM2-dependent glycolysis.

BACKGROUND: Glycolysis is a critical pathway in cellular glucose metabolism that provides energy and participates in immune responses. However, whether glycolysis is involved in NOD-like receptor family protein 3 (NLRP3) inflammasome activation and phagocytosis of macrophages in response to Treponema pallidum infection remains unclear. OBJECTIVES: To investigate the role of glycolysis in activating the NLRP3 inflammasome for regulating phagocytosis in macrophages in response to T. pallidum protein Tp47 and its associated mechanisms. METHODS: Interactions between activation of the NLRP3 inflammasome and phagocytosis and the role of glycolysis in Tp47-treated macrophages were investigated through experiments on peritoneal macrophages and human monocytic cell line-derived macrophages. RESULTS: Activation of phagocytosis and NLRP3 inflammasome were observed in Tp47-treated macrophages. Treatment with NLRP3 inhibitor MCC950 or si-NLRP3 attenuated Tp47-induced phagocytosis. Glycolysis and glycolytic capacity were enhanced by Tp47 stimulation in macrophages, and a change in the levels of glycolytic metabolites (phosphoenolpyruvate, citrate and lactate) was induced by Tp47 in macrophages. Inhibition of glycolysis with 2-deoxy-D-glucose, a glycolysis inhibitor, decreased the activation of NLRP3. Expression of M2 isoform of pyruvate kinase (PKM2), an enzyme catalysing a rate-limiting reaction in the glycolytic pathway, was upregulated in Tp47-stimulated macrophages. Inhibition of PKM2 with shikonin or si-PKM2 decreased glycolysis and NLRP3 activation. CONCLUSION: Tp47 promotes phagocytosis in macrophages by activating the NLRP3 inflammasome, which is induced by the enhancement of PKM2-dependent glycolysis.

Tp47 promoted the phagocytosis of HMC3 cells though autophagy induced by endoplamic reticlum stress.

BACKGROUND: Central nervous system damage is an essential clinical feature that occurs in the early or late stages of syphilis infection. The abnormal enhancement of microglial phagocytosis can cause damage to the nervous system. However, the contribution of abnormally enhanced microglial phagocytosis to the pathogenesis of Treponema pallidum subsp. pallidum (T. pallidum) infection remains unknown. OBJECTIVES: In this study, we sought to determine the role of recombinant T. pallidum Tp47 in promoting microglia phagocytosis and its associated mechanisms. METHODS: Microglial HMC3 cells were used to investigate the effect of the Tp47 on phagocytosis and the roles of autophagy and endoplasmic reticulum stress in Tp47-induced phagocytosis. RESULTS: HMC3 cells exhibited obvious phagocytosis when stimulated with Tp47. The levels of P62 degradation, Beclin1 expression and the LC3II/LC3I ratio were significantly elevated, and the fusion of autophagosomes and lysosomes was promoted in Tp47-stimulated HMC3 cells. Treatment with the autophagy inhibitors 3-MA and Baf A1 inhibited Tp47-induced phagocytosis. Meanwhile, the endoplasmic reticulum stress markers PERK, IRE1α, GRP78, ATF4 and XBP1s were upregulated in Tp47-stimulated HMC3 cells. In addition, we found that TUDCA could inhibit Tp47-induced expression of IRE1α but not PERK or ATF4. 4-PBA inhibited TP47-induced PERK and ATF4 protein expression but did not inhibit IRE1α expression. Attenuation of endoplasmic reticulum stress by administration of TUDCA and 4-PBA abrogated Tp47-mediated autophagy. CONCLUSIONS: These results suggested that Tp47 activated autophagy through two key pathways associated with endoplasmic reticulum stress, PERK/ATF4 and IRE1/XBP1, to promote phagocytosis in HMC3 cells. These findings provided a basis for the understanding of the pathophysiology of neurological disorders that occur during the course of syphilis.

[Effectiveness of the "14 plus 7 day quarantine" and "nucleic acid plus total antibody testing" strategy for screening imported patients with COVID-19 in Xiamen].

Objective: To analysis effectiveness of the "14 plus 7 day quarantine" and "nucleic acid plus total antibody testing" strategy (combined screening strategy) for screenin the imported patients with COVID-19 in Xiamen. Methods: The study populations were overseas travelers arriving in Xiamen from March 17 to December 31, 2020, and overseas travelers who had quarantine outside Xiamen for less than 21 days from July 18 to December 31, 2020. Data were collected and analyzed on the timing of detection, pathways, and test results of the imported patients with COVID-19 after implementing combined screening strategy. Results: A total of 304 imported patients with COVID-19 were found from 174 628 overseas travelers and 943 overseas travelers from other cities. A total of 163 cases (53.6%) were diagnosed by multitime, multisite intensive nucleic acid testing after positive finding in total antibody testing. Among them, 27 (8.9%) were first positive for nucleic acid in 14 plus 7 day quarantine and 136 were first positive for nucleic acid in 14-day quarantine. Only 8 of these individuals were tested positive for nucleic acid after positive total antibody testing. The other 128 individuals were tested positive for nucleic acid after being negative for average 2.3 times (maximum of 6 times). Aditional 155 cases might be detected by using the combined "14 plus 7 day quarantine" and " nucleic acid plus total antibody testing" strategy compared with "14-day quarantine and nucleic acid testing" strategy, accounting for 51.0% of the total inbound infections. So the combined screening strategy doubled the detection rate for imported patients with COVID-19. No second-generation case caused by overseas travelers had been reported in Xiamen as of February 26, 2021. Conclusions: Xiamen's combined screening strategy can effectively screen the imported patients with COVID-19 who were first positive for nucleic acid after 14 day quarantine. Compared with "14 day quarantine and nucleic acid testing", the combined screening strategy improved detection rate and further reduced the risk of the secondary transmission caused by the imported patients with COVID-19.

A simple method for moving source depth estimation applied to the SWellEx96 data.

Existing methods for source localization in an ocean waveguide generally require simultaneous range and depth estimation as they are intrinsically coupled in the acoustic field. Using beam intensities averaged over ranges longer than the mode cycle distances, it is shown that the range-averaged vertical beam distribution is insensitive to the source range and sensitive to the source depth. An incoherent matched beam processing method is presented and applied to the SWellEx96 moving source data to estimate source depth based on the 127 and 130 Hz signals with good results.

Beam-time delay domain deconvolved scheme for high-resolution active localization of underwater targets.

Matched filter (MF) and conventional beamforming (CBF) are widely used in active sonar; the performance of the former (temporal resolution) is limited by the signal bandwidth, and that of the latter (angular resolution) is limited by the array aperture. Previous work has shown that angular resolution can be significantly improved by deconvolving the CBF outputs. In this paper, deconvolution is extended to the time domain by deconvolving the MF outputs, and a high-resolution two-dimensional deconvolution method is proposed to simultaneously improve the temporal and angular resolution. Numerical simulations and experimental tank data show that angular resolutions are improved 26 times, and temporal resolutions are improved 10 times compared with the conventional MF and CBF methods. Reverberations are much suppressed to allow target echoes to be detected from the received time series data.

Deconvolution of decomposed conventional beamforming.

A recently proposed deconvolution method applied to conventional beamforming (CBF) shows a much higher array gain (AG) than CBF in theory, thereby providing the possibility for detecting a weak signal with a much lower signal-to-noise ratio (SNR). However, simulated data processing shows an effective AG that decreases with decreasing SNR. The reason for the performance loss is analyzed. A method based on deconvolution of the signal subspace of the CBF outputs is shown to recover most of the AG loss. It is used to trace a weak signal in bearing and time.

Matched beam-intensity processing for a deep vertical line array.

A vertical line array can be deployed in deep water below the critical depth, the depth where the sound speed equals the sound speed at the surface, to take advantage of the lower ambient noise level (compared with above the critical depth) for target detection. To differentiate a submerged source from a surface source, a Fourier transform based method [McCargar and Zurk, J. Acoust. Soc. Am. 133, EL320-325 (2013)] was proposed for a narrowband signal that exploits the depth-related harmonic (oscillation) feature of the beam power time series associated with the target arrival. In this paper, incoherent matched beam processing is used to estimate the target depth. Where the replica (calculated) beam intensity or amplitude time series best matches that of the data is used to estimate the source depth. This method is shown, based on simulated data, to provide a better depth resolution in general and better ability to estimate the depth of a very shallow source (say at 10 m) and can be used to complement the Fourier transform based method. It can be extended to process (random) broadband signals and to environments where the Lloyd's mirror theory is not valid.

Autophagy promotes phagocytosis and clearance of Treponema pallidum via the NLRP3 inflammasome in macrophages.

BACKGROUND: Elucidating the mechanism of the macrophage phagocytic response will improve our knowledge of host defence against Treponema pallidum. OBJECTIVE: To explore whether autophagy promotes T. pallidum phagocytosis and clearance via the NLRP3 inflammasome in macrophages. METHODS: The interactions between autophagy and phagocytosis and the role of NLRP3 in these processes in T. pallidum-treated macrophages were investigated through experiments using human monocytic cell line (THP-1)-derived macrophages. Treponema pallidum clearance after phagocytosis was evaluated by inoculating rabbits with macrophage-treponeme mixtures. RESULTS: Activation of autophagy and phagocytosis in T. pallidum-treated macrophages occurred in a dose- and time-dependent manner. The percentage of spirochete-positive macrophages (22.34% vs. 70.93%, P < 0.001) and spirochete internalization (MFI: 9.62 vs. 20.33, P < 0.001) were notably reduced by silencing Beclin1. Inoculation of macrophage-treponeme mixtures into rabbits showed a 3.00-day delay in lesion development (17.55 ± 3.73 vs. 14.55 ± 1.99 days) and decreased lesion numbers [11 (36.7%) vs. 20 (66.7%) of 30; χ2  = 5.406, P = 0.020] in the control compared with the si-Beclin1 group. Furthermore, silencing NLRP3 decreased the mRNA and protein levels of Beclin-1 and LC3B [mRNA: 49.86% and 43.02%; protein: 22.31% and 24.24%, respectively, differing significantly from the control group (P < 0.001)] and reduced the percentage of spirochete-positive macrophages (30.29% vs. 70.53%, P < 0.001) and spirochete internalization (MFI: 9.82 vs. 19.33, P < 0.001). CONCLUSION: Treponema pallidum induces autophagy in macrophages to promote phagocytosis and clearance. The NLRP3 inflammasome modulates autophagy and phagocytosis in vitro. These data may be useful for understanding the host-pathogen relationship and establish the groundwork for strategies to combat syphilis.

Joint towed array shape and direction of arrivals estimation using sparse Bayesian learning during maneuvering.

Large aperture towed arrays are widely used underwater to detect weak targets. During maneuvering, the beamformer performance degrades significantly if a wrong array configuration is assumed. Currently, engineering sensors and/or (augmented) acoustic sources are used to estimate the array element positions. The results are often inadequate depending on the number of measurements available. In this paper, an adaptive bow (AB) sparse Bayesian learning (SBL) algorithm is proposed, called ABSBL. Assuming the towed array follows a parabola shape during slow turns and treating the array bow as a hyperparameter in SBL, the bow and directions of arrival (DOAs) of the signals can be jointly estimated from the received acoustic data. Simulations show that ABSBL yields accurate estimates of the bow and target DOAs if the turning direction is known. ABSBL is applied to the MAPEX2000 data. The estimated array bow and DOA agrees with that estimated from relative time delays measured from acoustic pings and SBL, better than that estimated from the GPS data using the water-pulley model. The method can potentially be applied without engineering sensors.

Are nontreponemal tests suitable for monitoring syphilis treatment efficacy? Evidence from rabbit infection models.

OBJECTIVES: We aimed to characterize kinetics of non-treponamal antibody titres during the natural course of syphilis and explore their roles in monitoring syphilis treatment efficacy. METHODS: Sixty New Zealand white male rabbits were challenged with Nichols or Amoy Treponema pallidum strains, and the rapid plasma reagin (RPR) test was performed to quantify non-treponemal antibody titres during the infection course. Viable T. pallidum in the challenged rabbits was assessed with rabbit infectivity tests. RESULTS: The RPR titres of the Nichols or Amoy strain between no benzathine penicillin G (BPG) and BPG treatment subgroups displayed a similar trend: first ascending and then descending. Compared with baseline, the proportions of fourfold decline in RPR titres in the Nichols or Amoy group presented a similar result on days 30, 60 and 180 between the no BPG and BPG treatment subgroups (0%, 0/5; 80%, 4/5; 100%, 5/5; vs. 0%, 0/5; 80%, 4/5; 100%, 5/5; p 0.999; 0%, 0/5; 80%, 4/5; 80%, 4/5; vs. 40%, 2/5; 100%, 5/5; 100%, 5/5; p 0.098, respectively). Compared with the maximum baseline titre, the proportion of fourfold decline in PRR titre also showed a similar result in the two groups on days 30, 60 and 180 between the no BPG and the BPG treatment subgroups (0%, 0/5; 100%, 5/5; 100%, 5/5, vs. 40%, 2/5; 100%, 5/5; 100%, 5/5; p 0.129; 0%, 0/5; 100%, 5/5; 100%, 5/5, vs. 80%, 4/5; 100%, 5/5; 100%, 5/5; p 0.091, respectively. Moreover, regardless of whether the RPR titres presented a fourfold decline, viable T. pallidum could be detected in untreated rabbits' lymph nodes at 30, 60 and 180 days post infection, while viable T. pallidum was not detected in any of the treated rabbits' lymph nodes. CONCLUSIONS: The RPR titre increased and then decreased (even became negative) during the natural course of syphilis, similar to that seen after BPG treatment. The RPR tetre is thus a questionable indicator of syphilis treatment efficacy.

Recombinant Treponema pallidum protein Tp0136 promotes fibroblast migration by modulating MCP-1/CCR2 through TLR4.

BACKGROUND: Chancre self-healing is an important clinical feature in the early stages of syphilis infection. Wound healing may involve an important mechanism by the migration of fibroblasts filling the injured lesion. However, the specific mechanism underlying this process is still unknown. OBJECTIVES: We aimed to analyse the role of Tp0136 in the migration of fibroblasts and the related mechanism. METHODS: The migration ability of fibroblasts was detected by a wound-healing assay. RT-PCR and ELISA detected the expression of MCP-1, IL-6 and MMP-9. TLR4 expression was detected by RT-PCR. The protein levels of CCR2 and relevant signalling pathway molecules were measured by Western blotting. RESULTS: Tp0136 significantly promoted fibroblast migration. Subsequently, the levels of MCP-1 and its receptor CCR2 were increased in this process. The migration of fibroblasts was significantly inhibited by an anti-MCP-1 neutralizing antibody or CCR2 inhibitors. Furthermore, studies demonstrated that Tp0136 could activate the ERK/JNK/PI3K/NF-κB signalling pathways through TLR4 activity and that signalling pathways inhibitors could weaken MCP-1 secretion and fibroblast migration. CONCLUSIONS: These findings demonstrate that Tp0136 promotes the migration of fibroblasts by inducing MCP-1/CCR2 expression through signalling involving the TLR4, ERK, JNK, PI3K and NF-κB signalling pathways, which could contribute to the mechanism of chancre self-healing in syphilis.

Array gain of coprime arrays.

A coprime array of M + N - 1 elements is designed, using product processing (PP), to yield the same beam width as that of a full array of MN elements using conventional beamforming (CBF), while at the same time suppressing the grating lobes. The array gain (AG) for isotropic noise using conventional PP is slightly less than that obtained using CBF, namely, 10log(M + N - 1). It is shown that using the coherent product processing, the coprime array yields an AG equal to that of the full array of MN elements, 10log(MN). The superior gain is often referred to as supergain.

Recombinant Treponema pallidum protein Tp47 induces angiogenesis by modulating the matrix metalloproteinase/tissue inhibitor of metalloproteinase balance in endothelial cells.

BACKGROUND: Although angiogenesis is an obvious pathological manifestation in the pathogenesis of syphilis, little is known about the underlying mechanisms of angiogenesis induced by reactions to Treponema pallidum antigens. OBJECTIVE: In this study, we sought to determine the role of recombinant T. pallidum Tp47 in promoting angiogenesis in endothelial cells and the related mechanism. METHODS: Evaluation of the pro-angiogenic activity of recombinant T. pallidum Tp47 in human umbilical vein endothelial cells (HUVECs) was assessed, and the balance of matrix metalloproteinase (MMP)/tissue inhibitor of metalloproteinase (TIMP) and the mechanisms underlying the involvement of Akt/mTOR/S6 pathways in this process were explored. RESULTS: Under stimulation by Tp47, HUVECs exhibited obvious proliferation, migration and tube formation. In addition, the apparent promotion of angiogenesis by Tp47 was observed using a zebrafish embryo model. During angiogenesis, the levels of MMP-1 and MMP-10 were significantly elevated, whereas those of TIMP-1 and TIMP-2 did not change. In addition, after transfection with siRNAMMP-1 and siRNAMMP-10, migration and tube formation were significantly inhibited. Akt/mTOR/S6 signalling was found to be involved in upregulating MMP-1 and MMP-10 expression, and the sequential blockade of steps in the pathways effectively prevented Tp47-induced angiogenesis. CONCLUSION: The results reveal the underlying mechanism of angiogenesis promoted by Tp47, namely, upregulating MMP-1 and MMP-10 expression to disrupt the MMP/TIMP balance through the Akt/mTOR/S6 pathway. These findings contribute to our understanding of the pathophysiology of syphilis.

Superdirective beamforming applied to SWellEx96 horizontal arrays data for source localization.

Arrays employing superdirective beamforming can provide the same directivity and directivity index (or array gain) with less aperture as a large size array using conventional beamforming (CBF). Superdirective arrays offer a practical and significant improvement in the reception of low frequency signals and is useful for many applications where the array size is limited, such as a miniature microphone array or an underwater acoustic array with a limited aperture. Deconvolving the CBF is a method of superdirective beamforming. The improvement in directivity (beam width) and array gain is studied/illustrated using the SWellEx96 horizontal array data where only sub-arrays are used.

Analysis of serum metabolite profiles in syphilis patients by untargeted metabolomics.

BACKGROUND: Global metabolomics analysis can provide substantial information on energy metabolism, physiology, possible diagnostic biomarkers and intervention strategies for pathogens. OBJECTIVE: To gain a better understanding of the mechanisms of syphilis and analysis of serum metabolite profiles in syphilis patients. METHODS: We conducted an untargeted metabolomics analysis of serum from 20 syphilis patients and 20 healthy controls. RESULTS: A total of 2890 molecular features were extracted from each sample, and the peak intensity of each feature was obtained. Distinct differential metabolites were identified by principal component analysis, partial least squares-discriminant analysis and hierarchical clustering analysis. Furthermore, five metabolites were identified as significantly different by Student's t-test, including trimethylamine N-oxide, l-arginine, lysoPC(18:0), betaine and acetylcarnitine. KEGG analysis showed that these differential metabolites were in various pathways, including Chagas disease, fatty acid biosynthesis, primary bile acid biosynthesis, Salmonella infection, ABC transporters, glycerophospholipid metabolism and choline metabolism. Among them, trimethylamine N-oxide was 3.922 times in patients with syphilis than healthy controls. CONCLUSION: Trimethylamine N-oxide may be used as an indicator to distinguish between syphilis patients and healthy controls. The changes in these metabolites suggest that Treponema pallidum affects the normal metabolic activity of host cells, providing some clues for elucidating the pathogenesis of T. pallidum.

The association between body mass index, primary healthcare use and morbidity in early childhood: findings from the Born In Bradford cohort study.

OBJECTIVES: The objective of the article was to examine the association between body mass index (BMI), health and general practice (GP) healthcare use in early childhood. STUDY DESIGN: This study is a prospective cohort study. METHODS: Multivariate Poisson and logistic regression models were used to explore the association between BMI and health outcomes using data from the Born In Bradford cohort study, linked to routine data capturing objective measures of BMI at age 5 years, alongside GP appointment rates, GP prescriptions and specific morbidities in the subsequent 3-year period. RESULTS: Compared with healthy weight, children who were obese at the age of 5 years had significantly higher rates of GP appointments (incident rate ratio 1.14, 95% confidence interval [CI]: 1.06-1.23), GP prescriptions (incident rate ratio 1.15, 95% CI: 1.04-1.27), asthma (odds ratio 1.46, 95% CI: 1.21-1.77), sleep apnoea (odds ratio 2.50, 95% CI: 1.36-4.58), infections (incident rate ratio 1.19, 95% CI: 1.08-1.30), antibiotic prescriptions (incident rate ratio 1.25, 95% CI: 1.10-1.42) and accidents (incident rate ratio 1.20, 95% CI: 1.01-1.42) in the subsequent 3 years. Underweight children were found to have higher rates of GP appointments (incident rate ratio 1.25, 95% CI: 1.04-1.52), but there were no differences between overweight and healthy weight children. CONCLUSIONS: Childhood obesity was found to be associated with increased primary healthcare use and a range of poorer health outcomes at the age of 8 years, underlining the importance of reducing childhood obesity in early childhood.

Channel distortion on target scattering amplitude in shallow water.

Bistatic acoustic scattering uses echo returns from a target to estimate the scattered intensity or amplitude as a function of angle and frequency (acoustic color) for target classification. In a shallow water waveguide, the echo return from a target at a distance, such as a mine, is modified by the waveguide and deviates significantly from that at close range or in free space. The channel effect or distortion on the echo return is studied using simulated data. A simple frequency domain signal processing method is proposed to equalize the channel effect. The frequency and angle distribution of the estimated scattering function is compared with that of the original function. It is found to be an adequate representation of the original function with a high correlation coefficient (∼0.88).

Source localization in range-dependent and time-varying shallow water: The Shallow Water 2006 experimental results.

In a range-dependent and time-varying environment, such as at the Shallow Water 2006 (SW06) experimental site, matched field processing often has difficulty localizing a moving source emitting a narrowband signal when signal mismatch is difficult to mitigate given only the nominal sound speed profile and bottom properties along the source track. Based on the range-averaged mode wavenumbers and depth functions estimated from data received on a vertical line array by synthetic beamforming (without any environmental information) using Doppler shift as a reference, a method is proposed in this paper to search for the source depth first and then the source range. Source localization is demonstrated with the SW06 data for two source runs along and oblique to the shelf. Robustness is achieved by minimizing/breaking the coupling between range and depth, when one of them can be estimated using non-environment-related input.