Application of ion pair high performance liquid chromatography to the analysis of porphyrins in clinical samples

Induction of a chemoattractive proinflammatory cytokine response after stimulation of keratinocytes with Propionibacterium acnes and coproporphyrin III

BACKGROUND

The inflammation in acne vulgaris is widely thought to be induced by an immunological reaction, but the role of Propionibacterium acnes is unclear.

OBJECTIVES

To examine the local host response mechanism of a keratinocyte cell line 3 h and 6 h after stimulation with viable and heat-killed P. acnes.

METHODS

The quantitative expression of cytokines was measured at the mRNA level by real-time reverse transcription-polymerase chain reaction.

RESULTS

The coincubation of a keratinocyte cell line with viable, but not heat-killed, P. acnes modulated an adequate cytokine response for interleukin (IL)-1beta, granulocyte/macrophage colony-stimulating factor and IL-8. High-performance liquid chromatographic analysis of the in vivo porphyrin pattern secreted by P. acnes revealed a predominance of coproporphyrin III in acne lesions. This same porphyrin fraction also modestly induced IL-8 expression by keratinocytes.

CONCLUSIONS

This cytokine pattern may favour a chemotactic response and implicates P. acnes and coproporphyrin III in the recruitment of inflammatory cells to the site of infection and in the development of acne lesions.

Erythrocyte protoporphyrins in hepatitis C viral infection

OBJECTIVES

Protoporphyrin is the immediate precursor of the heme molecule. Due to a spillover from hemaotopoietic tissue it is regularly found in small amounts in erythrocytes and excreted into the bile. In hereditary erythropoietic protoporphyria excess protoporphyrin accumulates and can cause severe liver damage both by crystallization and induction of oxidative stress. The aim of this investigation was to study protoporphyrin concentrations in other liver disorders.

DESIGN AND METHODS

Erythrocyte protoporphyrin and zinc protoporphyrin concentrations were studied in 50 patients with chronic hepatitis C infection and various degrees of liver damage. High-performance liquid chromatographic analysis with fluorescence detection was used.

RESULTS

Erythrocyte protoporphyrin was increased in 32% of the patients studied; in 12 patients up to two-fold higher than the maximum of the reference range, in 4 up to three-fold higher (median concentration 98 nmol/L, interquartile range 68-142; maximum 379 nmol/L (reference range: <125 nmol/L)). In 6 of the 10 patients in the subgroup with signs of severe liver dysfunction (decreased serum albumin and prolonged thromboplastin time, elevated serum bilirubin), protoporphyrin was elevated. Erythrocyte zinc protoporphyrin was increased in 7 cases out of all 50 studied; in these seven cases, erythrocyte protoporphyrin was also elevated (median concentration of zinc protoporphyrin in the whole study group: 232 nmol/L, interquartile range 182-342; maximum 827 nmol/L (reference range <464 nmol/L).

CONCLUSIONS

Elevated erythrocyte protoporphrin levels are frequently found in patients with advanced chronic hepatitis C infection. Because protoporphyrin is well known to be hepatotoxic, these findings warrant further investigation.

Urinary porphyrin excretion in hepatitis C infection

A high prevalence of hepatitis C virus infection in porphyria cutanea tarda in some populations suggests a close link between viral hepatitis and alteration of porphyrin metabolism. Moreover, there is evidence of a role of porphyrinopathies in hepatocarcinogenesis. The aim of our study was to obtain data on the prevalence and patterns of heme metabolism alterations in patients with chronic hepatitis C virus infection. Urinary porphyrin excretion was prospectively studied in 100 consecutive outpatients with chronic hepatitis C infection without signs of photosensitivity, using an ion-pair high-performance liquid chromatography method. Increased total porphyrin excretion was found in 41 patients, with predominant excretion of coproporphyrins (whole study group: mean 146 microg/g creatinine, interquartile range 76-186; normal < 150), in 10 patients excretion exceeded 300 microg/g creatinine. In the majority of all patients studied (75/100) an increased ratio of the relatively hydrophobic coproporphyrin isomer I to isomer III was found. In just one case, urinary porphyrin pattern characteristic for chronic hepatic porphyria was present (uroporphyrin > coproporphyrin, heptacarboxyporphyrin III increased) but the total porphyrin excretion was only slightly elevated in this case. In the whole group, total urinary porphyrin excretion correlated well with serum bilirubin and was inversely correlated with albumin and thrombin time. In conclusion, secondary coproporphyrinuria occurs frequently in heptatitis C infection, whereas in Germany, preclinical porphyria cutanea tarda seems to be rare in these patients.

Investigations on the formation of urinary coproporphyrin isomers I-IV in 5-aminolevulinic acid dehydratase deficiency porphyria, acute lead intoxication and after oral 5-aminolevulinic acid loading

OBJECTIVES

Investigation of the metabolism of the four urinary coproporphyrin isomers I-IV in the extremely rare 5-aminolevulinic acid dehydratase (ALAD) deficiency porphyria (syn.: Doss porphyria), in acute lead intoxication, and after oral 5-aminolevulinic acid (ALA) loading.

DESIGN AND METHODS

We analyzed the excretion of total urinary coproporphyrins and the composition of the respective isomers I-IV with ion-pair HPLC methods in these conditions.

RESULTS

The concentration of total coproporphyrins was about 30-fold increased in patients with ALAD deficiency porphyria and acute lead intoxication as compared with controls. In addition, the proportion of coproporphyrin III as well as that of the atypical isomers II and IV were significantly elevated at the expense of isomer I. After oral ALA administration to normal volunteers, a 10- to 15-fold increase in the maximal concentration of total urinary coproporphyrins was observed within 12 to 24 h. Urinary levels were back to normal after another 24 h. The excretion pattern of the individual urinary coproporphyrin isomers I-IV after ALA ingestion revealed a dynamic process: initially isomer III was preferentially formed, followed by a 3-fold increase of isomers II and IV via non-enzymatic rearrangement of isomer III, and finally normalization of all four isomers occurred within 48 h.

CONCLUSIONS

These results demonstrate that oral ALA loading can be used as an in vivo model to study the metabolism of the four urinary coproporphyrin isomers I-IV especially in ALAD deficiency porphyria and in acute lead poisoning.

Intracellular fluorescence behaviour of meso-tetra(4-sulphonatophenyl)porphyrin during photodynamic treatment at various growth phases of cultured cells

Meso-tetra(4-sulphonatophenyl)porphyrin (TPPS4) taken up by cells is mainly localized in lysosomes as previously shown by fluorescence microscopical and fluorescence spectroscopical investigations. In the present study the intracellular fluorescence behaviour and the intracellular amount of this dye at various growth periods of cells were examined. For cells irradiated in the growth phase a relocalization of TPPS4 from the lysosomes into the cytoplasm and finally into the nucleus was observed. In contrast, for cells irradiated in the stationary phase no redistribution could be detected and therefore no evidence for severe damage of the lysosomal membranes and subsequently for the release of lytical enzymes is given. In both cases lethal damage of the cells was achieved as examined using the trypan blue exclusion test. This indicates that damage of the lysosomes is less important in the photodynamic inactivation of cells sensitized by TPPS4.