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RESEARCH REPORT |
1 Departments of Dental Diagnostic Science and
2 Community Dentistry, University of Texas Health Science Center at San Antonio;
3 HIV Unit, Department of Infectious Diseases, Wilford Hall Air Force Medical Center; and
4 Geriatric Research, Education and Clinical Center & Research Services, Audie L. Murphy Division, South Texas Veterans Health Care System, 7400 Merton Minter Boulevard, San Antonio, TX 78229-4404, USA;
* corresponding author, Yeh{at}uthscsa.edu
| ABSTRACT |
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KEY WORDS: HIV xerostomia saliva salivary glands
| INTRODUCTION |
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With respect to saliva composition, sodium and chloride are elevated in glandular saliva collected from HIV patients (Yeh et al., 1988; Mandel et al., 1992; Lin et al., 2001). The concentrations of antimicrobial and antifungal proteins such as lysozyme, lactoferrin, secretory IgA, and histatin may be increased, decreased, or unaltered (reviewed by Lin et al., 2001). The discrepancies in findings may result from cohort effects, i.e., the stage of HIV disease, the relatively small number of patients evaluated, and/or the wide variety of medications, many of which are xerostomic, taken by HIV patients. Other factors include the methods of saliva collection, analysis, and the large inherent individual variation in salivary parameters.
While xerostomia and salivary gland hypofunction in HIV-infected patients are usually attributed to xerostomic medications, whether salivary gland function can be compromised by HIV infection is unclear. This report describes the effects of early-stage HIV disease on salivary gland function in a well-defined HIV(+) cohort. The influence on salivary gland function of xerostomic medications taken by these patients is evaluated in an effort to discriminate between effects that may be due to xerostomic drugs and those due to disease.
| MATERIALS & METHODS |
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Saliva Collection and Sialochemistry Analysis
Unstimulated whole, parotid, and submandibular/sublingual saliva, as well as citrate-stimulated parotid and submandibular/sublingual saliva, samples were collected from each subject according to a published protocol (Yeh et al., 1998). For component analysis, each sample was divided into 100-µL aliquots and stored at -70°C.
Stimulated glandular saliva was analyzed for content of electrolytes (sodium, chloride, potassium, and calcium), total protein, secretory IgA, lysozyme, lactoferrin, and albumin (Lin et al., 2001). We used assay kits to determine uric acid (Sigma, St. Louis, MO, USA) and total anti-oxidant capacity (Total Antioxidant Status Assay Kit, Calbiochem, San Diego, CA, USA). Total cystatin content was determined by inhibition of papain activity (Henskens et al., 1993) in only submandibular/sublingual saliva, since that of parotid saliva is too low to be accurately determined by this method (Veerman et al., 1996).
Statistical Analysis
We used the non-parametric Mann-Whitney U test to analyze for differences in CD4+ number and viral load between the two HIV(+) medication subgroups. These two variables are given in the text and Tables as medians, with the 25th to 75th percentiles in parentheses. All data for parametric analyses (except age) were square-root-transformed for analysis (Yeh et al., 2000). The values in the Tables and text indicate the non-transformed mean ± one standard error. We used the non-paired t test to determine differences between the HIV(+) group and Control. To determine if differences in salivary concentrations were related to the effects of flow rates on the glandular components, we used the Analysis of Covariance with flow rate as the covariate. To examine for effects of xerostomic medications, we used Analysis of Variance with Group [Control and both HIV(+) medication groups] as the independent variable. For the above analyses, p < 0.05 was considered significant. We used the Bonferroni/Dunn post hoc test to determine between-group differences (p
0.0167 required).
| RESULTS |
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Sialochemistry of Stimulated Submandibular/Sublingual Saliva
The concentrations of sodium and calcium were lower and those of potassium, albumin, lactoferrin, and secretory IgA were higher in the HIV(+) group as compared with Control (Table 4
). There were no differences in the concentrations of chloride, total protein, cystatin, lysozyme, total anti-oxidant capacity, and uric acid. When flow rate was introduced as a covariate in the analysis, the concentrations of calcium, secretory IgA, and total anti-oxidant capacity differed between the HIV(+) group and Control. With respect to the effects of medications, the concentrations of sodium and calcium were significantly reduced, while the concentrations of albumin and secretory IgA were significantly increased for both HIV(+) medication subgroups as compared with Control. Potassium and total protein concentrations were increased only in the HIV(+) xerostomic medication group. There was no significant difference between the two HIV(+) medication subgroups in any component.
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| DISCUSSION |
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One aspect of this study was to determine if the alterations in salivary gland function were related to the taking of xerostomic medications. The criteria for assigning a drug as xerostomic were based on a database of xerostomic drugs (Sreebny and Schwartz, 2002). It should be noted that the classification of a drug as xerostomic was based on clinical complaints reported by patients during the drug trial and not on objective measurements of salivary function. In a drug trial, subjective complaints of xerostomia are usually made by < 10% of the subjects. For example, most of the protease inhibitors have a xerostomia incidence of less than 3%. Thus, the vast majority of the subjects taking these medications do not experience xerostomia, and this may be the reason for our failure to see a difference between the two groups. There are reports that salivary function is decreased as the number of medications taken increases (Wu and Ship, 1993). In this study, the xerostomic medication group took an average of 5.0 medications vs. 2.1 for those taking medications in the non-xerostomic medication group. In summary, these results suggest that the taking of xerostomic medications, or the taking of medications in general, does not confound the effect of the disease on the gland. Another explanation may be that the effect of the disease on the gland may mask the effect of the taking of medications.
HIV-associated salivary gland disease (HIV-SGD), usually defined with a sicca syndrome (dry mouth) and salivary gland enlargement, is well-documented (Schiødt, 1992). It is unclear whether salivary gland dysfunction in early HIV infection is a contingent process prior to the development of full-blown HIV-SGD or is a different entity. Many HIV-SGD patients have Sjögrens-like syndrome with hyperglobulinemia along with diffuse and/or infiltrative lymphocytes within the salivary gland [also called diffuse infiltrative lymphocytosis syndrome (DILS)] (Smith et al., 2000; Patel and Mandel, 2001). Others have attributed the symptoms to cytomegalovirus (CMV) infection (Greenberg et al., 1997). Therefore, salivary gland dysfunction in early HIV infection could be secondary to autoimmunity or other infections. The nature of the salivary dysfunction warrants further investigation.
Alteration of salivary function in HIV infection could have clinical implications. Even though the difference in concentrations of electrolytes between the two groups is related to flow rate, the fact that concentrations differ may be clinically relevant, for it is well-established that ionic strength can modify antimicrobial properties of several salivary proteins (Oppenheim et al., 1988). With respect to other components of saliva, albumin and secretory IgA are increased for both stimulated parotid and submandibular/sublingual saliva in HIV(+). Elevation of salivary albumin may be indicative of gland inflammation (Fox et al., 1985). Although the concentrations of many components may be increased with HIV(+), owing to the reduction in flow rate, the amount delivered to the oral cavity per unit time is reduced. For both stimulated parotid and stimulated submandibular/sublingual saliva, this includes lysozyme, total anti-oxidant capacity, and uric acid. In addition, for stimulated submandibular/sublingual saliva, the output of cystatin is reduced. The only component showing an increased secretory rate is that of secretory IgA in stimulated submandibular/sublingual saliva. The marked reduction in output of several salivary components, including the traditional antimicrobial/antifungal proteins and proteins having anti-oxidant potential (including uric acid), may contribute to the clinical oral manifestations of this disease.
The findings reported in this paper indicate that HIV(+) patients have alterations in both salivary gland fluid and component secretion, and that these changes occur in the early stages of this disease. Since salivary dysfunction occurs early in the disease process, a more vigorous prophylactic regimen could be beneficial to these patients in the prevention of oral disease associated with reduced salivary gland function.
| ACKNOWLEDGMENTS |
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Received October 18, 2002; Last revision May 9, 2003; Accepted June 25, 2003
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