| BackgroundAcne vulgaris is one of the most frequently occurred skin diseases, but its etiology has not been confirmed. The dominant skin microorganism, Propionibacterium acnes (P. acnes), was postulated the etiology, however, direct evidence has never been achieved. A characteristic red fluorescence, induced by long wave ultraviolet (UVRF) from P. acnes, attributed to porphyrins synthesized by P. acnes and related to its density, has been used as an effect indicator of antibiotic treatment in acne vulgaris. In our daily work, we found that in some patients, the UV induced fluorescence (UVF) of acne lesions was not red, but was red in normal skin follicles. This phenomenon is controversial to the postulation that P. acnes is the etiology of acne. Starting from this unexpected fact, we carried out this surface to inside study to confirm the relationship of UVF color and acne lesions.Objectives1) To investigate the ultraviolet induced surface fluorescence (UVF) color (especially UVRF) pattern of the comedonal and non-comedonal follicles in acne vulgaris patients.2) To confirm whether the UVF color distribution of isolated single comedonal corneum plugs, or the "inside UVF", is in accordance with that of the surface.3) To study the correlations between skin superficial UVRF color intensity and inflammation severity in acne patients, and to confirm whether porphyrins (the source of UVRF) is the possible reason of acne inflammation.4) To observe what other microorganisms are in the comedonal follicles, and to isolate and identify the typical and repeatedly observed ones. Eventually, to confirm the relationship between UVRF (which represents the existence of P. acnes) and acne lesions based on above studies, to facilitate further investigations on other microorganisms in the lesional follicles of acne, and finally help to elucidate the etiology(ies) and a cure for the disease.Materials and Methods1) Topical skin areas with acne lesions of 45 patients were photographed under stereomicroscope with natural light and long-wave UV respectively to obtain natural light and UV photos. Surface UVF colors of 398 lesional and non-lesional follicles were statistically analyzed.2) UVF color of 276 corneum plugs were randomly isolated from comedonal lesions, then photographed under fluorescence microscope and analyzed according to their UVF patterns. UVF color distribution of surface and inside UVF of lesional follicles were compared.3) Follicle superficial UVRF color intensity, represented by normalized R channel, was segmented and measured by ImageJ from UVF photos captured by the VISIA system. Inflammation severity was analyzed based on the Red photos captured by the VISIA system. The correlation of superficial UVRF color intensity and inflammation severity were calculated and examined.4) A newly designed staining protocol that enables simultaneous observation of both bacteria and fungi in the corneum plugs were used to investigate the morphologies (and species when possible) of microorganisms in the corneum plugs, and the occurrence of Malassezia spp. was calculated. Morphologically typical microorganisms were isolated and identified.Results1) 86.8% of comedonal follicles are non-red fluorescent,13.2% are red, while 89.1% of non-comedonal follicles are red fluorescent under UV (n=398, x2=222.87, P<0.01);2) UVF color of 89.0% of the isolated corneum plugs is non-red or mainly non-red, while 11.0% mainly red; This proportion complies well with that of surface UVF color of lesional follicles.3) The correlation between UVRF and skin inflammation severity is not statistically significant (n=45,r2=0.17, P>0.05).4) More than 10 morphologically typical substances that are probably microorganisms, such as coccoid, floccular, rod-shaped, fusiform, diphtheroid-rods, small oval, bright filaceous, long and curly bacillus-form etc, were observed from fresh smears of corneum plugs sampled from comedones of 45 patients. Malassezia spp. was detected of very high density in 53.0% of the patients, while of lower density in 9.0%, and of absence in the remaining 38.0%.ConclusionsBy a surface-to-inside process and follicle-by-follicle manner of investigation, we confirmed that the UVF color of comedonal lesions is mainly non-red, while non-lesional follicles mainly red in acne patients. Since UVRF is caused by and correlated to the density of P. acnes, as verified by us in the study, our results suggest that P. acnes may be of low density or even absence in the comedonal lesions of acne. Therefore its role as an etiology of acne is questionable.Chromatological and iconological analysis confirmed that UVRF is not correlated to acne inflammation severity. Therefore, pouphyrins may be not the cause of inflammation.A dozen of microbial species were observed, or isolated and identified from the smears of comedonal corneum plugs, of which Malassezia spp. is of very high density in 53.0% of the acne patients. By morphological evidences, we found that the dominant microorganism(s) vary in different acne patients, suggesting that the relationship of acne and microbials are complicated, and it is necessary to investigate the roles of such microbials in the pathogenesis and development of acne. Combined with previous studies and disputes on the role of P. acnes, our results support a challenge to the postulation that P. acnes is the etiology of acne, which was proposed 123 years ago.Further and direct evidences about the presence and spatial distribution of P. acnes in acne lesions, as well as investigations on the relationships between other microbials and acne, are warranted to confirm their role of such microbials in acne.This study is meaningful and valuable to the promotion and breakthrough in the studies concerning acne related microbial etiologies. |
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