Stephen Challacombe

Prof. Stephen Challacombe

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Research Focus & Metrics

Academic Career Length

55Years (1972-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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26 October 2016 in Arthritis & Rheumatology
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CSCaroline H. Shiboski
Caroline H. Shiboski
SCStephen Challacombe
Stephen Challacombe
RSRaphaèle Seror
Raphaèle Seror
LCLindsey A. Criswell
Lindsey A. Criswell
MLMarc Labetoulle
Marc Labetoulle
TGthe International Sjögren's Syndrome Criteria Working Group
the International Sjögren's Syndrome Criteria Working Group
Objective: To develop and validate an international set of classification criteria for primary Sjögren's syndrome (SS) using guidelines from the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR). These criteria were developed for use in individuals with signs and/or symptoms suggestive of SS.Methods: We assigned preliminary importance weights to a consensus list of candidate criteria items, using multi‐criteria decision analysis. We tested and adapted the resulting draft criteria using existing cohort data on primary SS cases and non‐SS controls, with case/non‐case status derived from expert clinical judgment. We then validated the performance of the classification criteria in a separate cohort of patients.Results: The final classification criteria are based on the weighted sum of 5 items: anti‐SSA/Ro antibody positivity and focal lymphocytic sialadenitis with a focus score of ≥1 foci/4 mm2, each scoring 3; an abnormal ocular staining score of ≥5 (or van Bijsterveld score of ≥4), a Schirmer's test result of ≤5 mm/5 minutes, and an unstimulated salivary flow rate of ≤0.1 ml/minute, each scoring 1. Individuals with signs and/or symptoms suggestive of SS who have a total score of ≥4 for the above items meet the criteria for primary SS. Sensitivity and specificity against clinician‐expert–derived case/non‐case status in the final validation cohort were high, i.e., 96% (95% confidence interval [95% CI] 92–98%) and 95% (95% CI 92–97%), respectively.Conclusion: Using methodology consistent with other recent ACR/EULAR‐approved classification criteria, we developed a single set of data‐driven consensus classification criteria for primary SS, which performed well in validation analyses and are well‐suited as criteria for enrollment in clinical trials.

9 January 2012 in Arthritis Care & Research
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SSS. C. Shiboski
S. C. Shiboski
CSC. H. Shiboski
C. H. Shiboski
LCL. A. Criswell
L. A. Criswell
ABA. N. Baer
A. N. Baer
SCStephen Challacombe
Stephen Challacombe
SGSjögren's International Collaborative Clinical Alliance (SICCA) Research Groups
Sjögren's International Collaborative Clinical Alliance (SICCA) Research Groups
Objective: We propose new classification criteria for Sjögren's syndrome (SS), which are needed considering the emergence of biologic agents as potential treatments and their associated comorbidity. These criteria target individuals with signs/symptoms suggestive of SS.Methods: Criteria are based on expert opinion elicited using the nominal group technique and analyses of data from the Sjögren's International Collaborative Clinical Alliance. Preliminary criteria validation included comparisons with classifications based on the American–European Consensus Group (AECG) criteria, a model‐based “gold standard” obtained from latent class analysis (LCA) of data from a range of diagnostic tests, and a comparison with cases and controls collected from sources external to the population used for criteria development.Results: Validation results indicate high levels of sensitivity and specificity for the criteria. Case definition requires at least 2 of the following 3: 1) positive serum anti‐SSA and/or anti‐SSB or (positive rheumatoid factor and antinuclear antibody titer ≥1:320), 2) ocular staining score ≥3, or 3) presence of focal lymphocytic sialadenitis with a focus score ≥1 focus/4 mm2 in labial salivary gland biopsy samples. Observed agreement with the AECG criteria is high when these are applied using all objective tests. However, AECG classification based on allowable substitutions of symptoms for objective tests results in poor agreement with the proposed and LCA‐derived classifications.Conclusion: These classification criteria developed from registry data collected using standardized measures are based on objective tests. Validation indicates improved classification performance relative to existing alternatives, making them more suitable for application in situations where misclassification may present health risks.

1 September 2003 in Microbiology and Molecular Biology Reviews
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JNJulian Naglik
Julian Naglik
SCStephen Challacombe
Stephen Challacombe
Bernhard HubeBernhard Hube
Bernhard Hube
SUMMARY: Candida albicans is the most common fungal pathogen of humans and has developed an extensive repertoire of putative virulence mechanisms that allows successful colonization and infection of the host under suitable predisposing conditions. Extracellular proteolytic activity plays a central role in Candida pathogenicity and is produced by a family of 10 secreted aspartyl proteinases (Sap proteins). Although the consequences of proteinase secretion during human infections is not precisely known, in vitro, animal, and human studies have implicated the proteinases in C. albicans virulence in one of the following seven ways: (i) correlation between Sap production in vitro and Candida virulence, (ii) degradation of human proteins and structural analysis in determining Sap substrate specificity, (iii) association of Sap production with other virulence processes of C. albicans, (iv) Sap protein production and Sap immune responses in animal and human infections, (v) SAP gene expression during Candida infections, (vi) modulation of C. albicans virulence by aspartyl proteinase inhibitors, and (vii) the use of SAP-disrupted mutants to analyze C. albicans virulence. Sap proteins fulfill a number of specialized functions during the infective process, which include the simple role of digesting molecules for nutrient acquisition, digesting or distorting host cell membranes to facilitate adhesion and tissue invasion, and digesting cells and molecules of the host immune system to avoid or resist antimicrobial attack by the host. We have critically discussed the data relevant to each of these seven criteria, with specific emphasis on how this proteinase family could contribute to Candida virulence and pathogenesis.

1 March 2010 in American Journal of Ophthalmology
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JWJohn P. Whitcher
John P. Whitcher
CSCaroline H. Shiboski
Caroline H. Shiboski
SCStephen Challacombe
Stephen Challacombe
AHAna Maria Heidenreich
Ana Maria Heidenreich
KKKazuko Kitagawa
Kazuko Kitagawa
TDTroy E. Daniels
Troy E. Daniels

1 December 1980 in Journal of Experimental Medicine
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SCStephen Challacombe
Stephen Challacombe
TTT B Tomasi
T B Tomasi
Diminished systemic immune reaction after ingestion of antigen has been reported in several animal models. Conversely, it has been reported recently that oral immunization may lead to the production of secretory antibodies. To determine whether these events could occur concurrently, CBA/J mice were immunized intragastrically with varying doses of ovalbumin (OVA) and Streptococcus mutans. After 7 d, the animals were challenged systemically with antigen in complete adjuvant and 8 d later serum and saliva taken, and the draining lymph nodes assayed for a proliferative response. Intragastric doses of 1 mg OVA or 10(9) S. mutans led to significant suppression of the proliferative response, and intragastric doses of 10 mg OVA or 2.5 X 10(9) S. mutans led to the production of detectable salivary antibodies using hemagglutination. Serum antibodies were not detected after intragastric administration of OVA or S. mutans. Suppression of the proliferative response could be detected from 2-60 d after intragastric administration of OVA, and 2-21 d after S. mutans. Prior intragastric immunization with heterologous antigens did not suppress the response to OVA or S. mutans. Transfer of 40 X 10(6) mesenteric lymph node cells from mice given 20 mg OVA or 10(9) S. mutans led to suppression of the proliferative response in syngeneic recipients. Salivary antibodies wer removed by absorption with anti-IgA, but not anti-IgG or IgM, indicating that they were of the IgA class. It appears that intragastric administration of soluble or particulate antigens in mice may lead to the concurrent induction of salivary antibodies and systemic suppression.

1 September 2010 in Cell Host & Microbe
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DMDavid Moyes
David Moyes
MRManohursingh Runglall
Manohursingh Runglall
CMCelia Murciano
Celia Murciano
CSChengguo Shen
Chengguo Shen
DNDeepa Nayar
Deepa Nayar
JNJulian Naglik
Julian Naglik
Discriminating between commensal and pathogenic states of opportunistic pathogens is critical for host mucosal defense and homeostasis. The opportunistic human fungal pathogen Candida albicans is also a constituent of the normal oral flora and grows either as yeasts or hyphae. We demonstrate that oral epithelial cells orchestrate an innate response to C. albicans via NF-κB and a biphasic MAPK response. Activation of NF-κB and the first MAPK phase, constituting c-Jun activation, is independent of morphology and due to fungal cell wall recognition. Activation of the second MAPK phase, constituting MKP1 and c-Fos activation, is dependent upon hypha formation and fungal burdens and correlates with proinflammatory responses. Such biphasic response may allow epithelial tissues to remain quiescent under low fungal burdens while responding specifically and strongly to damage-inducing hyphae when burdens increase. MAPK/MKP1/c-Fos activation may represent a "danger response" pathway that is critical for identifying and responding to the pathogenic switch of commensal microbes.