Transvascular transport and distribution of fluid and protein in psoriasis

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Transvascular transport and distribution of fluid and protein in psoriasis Bent Staberg, M.D., Anne-Marie Worm, M.D., Per Klemp, M.D., and Niels Rossing, M.D.

Copenhagen, Denmark By combining the suction blister technic with studies of tracer protein kinetics, we have investigated the leakiness of the microvasculature and the distribution of extracellular water and plasma proteins in patients with psoriasis vulgaris. As in patients with extensive, erythrodermic skin diseases, we found a shift of fluid from the intra- to the extravascular spaces and an increased transcapillary escape rate of albumin (TERatb), which is a measure of the relative efflux of macromolecules from the total microvasculature. The appearance rate of intravenously injected labeled albumin in the extravascular fluid of newly formed suction blisters was significantly elevated in involved psoriatic skin as compared to uninvolved skin and skin of normal individuals. The blister fluid concentration of four endogenous plasma proteins (albumin, transferrin, IgG, and ot~-macroglobulin) was within normal range in involved skin and decreased in uninvolved skin. The calculated intravascular and extravascular masses of albumin were decreased but distributed normally within and outside the vascular system. It is suggested that the reduction in total albumin mass might be induced by an increased extravasation of albumin through the psoriatic skin vessels, causing an increased fractional catabolism of endogenous albumin. It is concluded that the leakiness of the microvasculature of involved psoriatic skin is increased, and this increase is compensated by an increased lymphatic drainage. These findings are discussed in the light of previously described histologic alterations in psoriatic skin. (J AM ACAD DERMATOL8: 193-199, 1983.)

Ultrastructural studies of the psoriatic skin have shown dilated capillaries with endothelial cell gaps in the upper dermis, indicating an increased vascular permeability. 1 Possibly alterations in the From the Department of Clinical Physiology and Dermatology, The Finsen Institute, and The Department of Dermato-venerology, Hvidovre Hospital. Supported by the Danish Psoriasis Society. Accepted for publication June 4, 1982. Reprint requests to: Dr. Bent Staberg, Department of Clinical Physiology, The Finsen Institute, Strandboulevarden 49, DK-2100 Copenhagen ~, Denmark. 0190-9622/83/020193+07500.70/0

© 1983 A m Acad Dermatol

dynamics of fluid and proteins in the skin could be detectable for the body as a whole, since the skin is a large organ containing 30% of the total extravascular albumin mass .2 Actually several studies have shown a significantly increased overall microvascular leakage of albumin in patients with extensive skin diseases, including patients with psoriasis, a'4 The overall leakage of albumin from plasma was, however, only slightly elevated in patients with varying degrees of psoriasis. ~ In patients with extensive skin diseases, including psoriasis, an in-

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Table I. Clinical data, plasma volume (PV), extracellular fluid volume (ECV), interstitial fluid volume (IFV), transcapillary escape rate o f albumin (TER), appearance rate of labeled albumin in blister fluid (Ab/As) from uninvolved (I) and involved (II) skin in ten patients with psoriasis Case

Surface area

Skin involvement

PV

ECV

I]

No,

(m2)

(%)

(liter/m 2)

(liter/m 2 )

]

2.18 2.08 1.88 2.01 1.93 1.88 1.83 1.73 2.15 1.95

80 70 40 30 40 40 60 50 40 60

1.93 1.85 1.35 1.35 1.87 1.34 1.09 1.47 ---

7.71 7.77 5.57 5.43 6.56 5.96 5.85 6.54 ---

5.78 5.92 4.22 4.08 4.69 4.62 4.76 5.07 --

1.96 0.14

51 16

1.53 0.31

6.42 0.91

4.89 0.67

1.64 0.15 NS

5.91 0.75 NS

4.27 0.67 NS

1 2 3 4 5 6 7 8 9 10

Patients Mean -+S.D. P Controls* Mean -+S.D. p

1.80 0.19 NS

IFV (liter/m *)

*Values from Rossing N, Worm A-M: Clin Physiol 1:275, 1981,

creased extravasation of plasma proteins from the skin microvasculature has been demonstrated. 6 It was the aim of the present study to measure and compare the local skin microvascular leakiness of plasma albumin and the extravascular concentrati0n of different-sized endogenous plasma proteins in involved and uninvolved psoriatic skin. Furthermore, we have measured the fluid distribution in patients with varying degrees of psoriasis, MATERIAL Eight male and two female patients with psoriasis vulgaris involving on an average 51% of the skin surface area (range, 30%-80%) were examined after having given informed consent (Table I). The mean age of the patients was 49 years (range, 22-74 years), the mean weight 83 kg (range, 70-100 kg), and the mean height 173 cm (range, 162-182 cm). The diagnosis was based on the clinical picture. The patients were examined when the psoriasis was in an active but stable phase. Pustular psoriasis and guttate psoriasis were not included. The patients had no concomitant diseases as judged by clinical and laboratory examinations. No top-

ical treatment was allowed 3 days prior to the investigation, and none of the patients received any systemic treatment. The extent of the skin involvement was assessed by the "rule of nines."

METHODS Each study was carried out in the morning after at least 12 hours of fasting and 30 minutes of rest in the supine position to stabilize lymph flow and extracellular body fluid volumes. The thyroid uptake of radioactive iodine was blocked by potassium iodide in a daily dose of 100 mg orally for 3 days. Metabolically genuine human albumin labeled with 131I (Kjeller, Norway) was used as protein tracer. Inulin (Laevosan; Gesellschaft, Linz, Austria), 10 gm/100 ml, was used for determination of the extracellular fluid volume by the bolus injection technic, r Weighed volumes of about 8 /zCi of the radioiodine-labeled protein and 40 ml of inulin were injected into one arm vein. Venous blood samples were drawn with a syringe and without stasis from the other ann once before and during the next 180 rain after injection at specified intervals.

The transcapillary escape rate of albumin (TERalb) was determined as the rate constant of the initial disap-

Volume 8 Number 2 February, 1983

Transvascular transport and distribution in psoriasis

Ab/As(% × hr-I)

pv/~v

TER

j

(%IVMxhr -~)

[

I

0.33 0.31 0.32 0.33 0.40 0.29 0.23 0.29

8.3 7.6 7.5 5.8 3.5 6.8 8.6 6.4

9.9 5.1 1.6 3.3 8.9 7.3 4.7 4.4

14.1 29.9 16.1 6.2 11.9 27.6 9.9 tl.5

0.31 0.05

6.8 1.6

5.7 2.8

15.9 8.5 <0.02

0.39 0.06 <0.01

5.1 1.2 <0.05

8.3 2.6 NS

<0.02

pearance of the tracer. TER represents the fraction of the intravascular mass of the studied protein that passes to the extravascular spaces per unit time. Plasma volume (PV) was determined as the initial laq-albumin distribution space calculated by extrapolation of the disappearance curve to time zero. The intravascular mass of albumin (IVMaltO was calculated as the product of plasma volume and concentration. Further details of the procedure and theoretical considerations have been published previously by others, s Extracellular volume (ECV) was determined as the inulin distribution volume, r equaling the mean transit time divided by the total clearance as calculated from the plasma disappearance curve of inulin. 9 The declining inulin concentration in the plasma samples taken over 180 minutes was determined by a colorimetric method and corrected for the glucose extinction. ~0 Interstitialfluid volume (IFV) equals EC V minus P V. The extravascular mass of albumin (EVMata) was estimated from the following equation: EVM= IFV' (C~a{,I')" (,!00 - IOOA')+Cb(II) ' A,) where A is the skin involvement in percent and

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Cbfl) and Cb(II) the concentration of albumin in the blister fluid from uninvolved and involved skin, respectively. Total mass of albumin (TMatb) is the sum of the intravascular and the estimated extravascular albumin masses, Distribution ratio (D) is the intravascular to total mass of albumin. Suction blisters, Thirty minutes after injection of the radiolabeled albumin and inulin, suction was applied to the abdominal skin to produce blisters as described by Kiistala.ll Four transparent plastic suction cups each with five holes were used, The cups were placed on the abdominal skin. Two cups were placed on clinically normal skin and two on psoriasis plaques at a minimum of 1 cm from the margins of the plaques. Blisters developed after about 2 hours of suction with a negative pressure of 200 mm Hg. The blister fluid from the involved and uninvoived psoriatic skin was collected separately in syringes after puncture of the blisters with Mantoux needles, Only noncolored blister fluid was used as these fluids contained spectrophotometrically (Beckman) unmeasurable amounts of hemoglobin and were therefore considered to be derived fully from the extravascular space. The lalI radioactivity accumulated in 1 ml blister fluid/60 rain was calculated from the total blister activity and the period of suction and then expressed as a percentage of the mean plasma activity (As) over the same period. In two subjects, radioactivity measurements were performed both before and after protein precipitation to secure that the radioactivity in the blister fluid was protein-bound. The supernatant contained no detectable free lalI. The tracer protein studies were not performed in two patients (Cases 9 and 10). Protein determination, The concentrations in the plasma samples (Cs) and the blister fluids (Cb) of albumin (molecular weight, 69,000), transferrin (molecular weight, 90,000), IgG (molecular weight, 175,000), and oe~-macroglobulin (molecular weight, 800,000) were determined by radial immunodiffusion: z STATISTICS The results were compared with those obtained by exactly the same technic in ten normal control subjects (six male and four female) with a mean age of 47 years (range, 21-70 years), mean weight of 68 kg (range, 53-85 kg), and mean height of 171 cm (range, 156-180 cm). lz Student's t test for

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Dermatology

Table 1I, Data on the concentration of endogenous proteins in serum (Cs) and blister fluid (Cb) from uninvolved (I) and involved (]I) abdominal skin in ten patients with psoriasis Cb(gm/liter)

Cs (gin/liter)

Alb. Case No.

Alb.

Transf.

IgG

~°m

,

1 2 3 4 5 6 7 8 9 10 Patients Mean --z-S.D. P Controls* Mean -S.D. p

29.4 29.8 35.1 36.8 44.9 35.2 30.3 36.2 28.6 36.2

2.23 2.15 3.00 3.29 2.66 3.17 2.94 2.53 1.08 2.13

5.5 12.0 8.6 7.5 14.7 10.7 9.3 7.9 4.8 12.9

1.13 1.45 3.05 3.70 1.41 1.41 2.33 1.48 1.34 1.40

10.3 12.3 9.2 12.2 19.9 17.7 12.9 12.7 12.1 14.9

12.3 16.2 12.4 11.6 20.5 22,3 11.4 14.4 14.6 23.0

34.3 5.0

2.52 0.66

9.4 3.2

1.87 0.87

13.4 3.3

15.9 4.5

l

1I

<0.05 38.6 2.5 <0.05

2.63 0.32 NS

10.5 0.9 NS

2.32 0.99 NS

21.1 2.5 <0.001

<0.01

Alb.: Albumin; Transf.: transferrin; a~-m: (x~-macroglobulin. * Values from Rossing N, Worm A-M: Clin Physiol 1:275, 1981.

paired and unpaired observations was used for statistical evaluation. RESULTS PV was on an average 7% lower and IFV 15% higher in the patient than in the control group, but the differences were not significant. The mean PV/IFV ratio of the patients (0.31 ± 0.05 S.D.) was significantly lower than that of the control subjects (0.39 +--0.06 S.D.) (p < 0.01) (Table I). TERam of the patients (mean, 6.8% IVM • hr-~ ± 1.6 S.D.) was significantly higher than that of the control group (mean, 5.1% IVM • hr -1 ± 1.2 S.D.) (p < 0.05). TERalb was positively correlated to the area of involved skin (r = 0.75, p < 0.05) (Table I), if the TERam value of Patient 5 was excluded. This patient deviated from the others with a value of TERalb below and an albumin concentration in serum above the respective mean values of the controls. The mean accumulation rate of radiolabeled al-

bumin from involved psoriatic skin ( 1 5 . 9 % . hr -1 __.8.5 S.D.) was significantly higher than that from uninvolved psoriatic skin ( 5 . 7 % " hr -1 ± 2 . 8 S.D.) (p < 0.02), the latter of which did not differ significantly from that of the control group (8.3% • hr -~ _-2-2.6 S.D.) (Table I). Table II shows the endogenous plasma protein concentrations in serum (Cs) and blister fluid (Cb). The mean serum concentrations of all measured proteins were lower in the patients than in the controls, but only the albumin concentration differed significantly (p < 0.05). In the blister fluid, all the mean plasma protein concentrations were significantly lower from uninvolved psoriatic skin than those from involved psoriatic skin and from the skin of the control group. Both the estimated intravascular and extravascular masses of albumin were lowered to the same extent as compared to the control values. Thus the mean distribution ratio of albumin of the patients was normal (Table III).

Volume 8 Number 2 February, 1983

Transvascular transport and distribution in psoriasis

Table III. Mean values of IVM,* E V M , t TM,* and D§ in eight patients with psoriasis and ten control subjects

Cb (gm/liter) Transl'.

0.76 0.91 0.94 0.96 1.12 1.32 0.90 0.63 0.81 0.99

0.86 1.16 1.27 0.94 1.18 2.12 0.98 0.93 1.04 1.89

.[,

IgG,

1.4 3.2 2.1 1.8 5.2 2.9 2.6 2.2 3.8 5.1

2.0 4.3 3.3 1.4 5.9 7.1 3.2 2.5 3.9 6.4

197

I

on-m

IVM (gmlm~)

I EVM ] (gmlm~)

TM (gmlm~)

D (%)

53 14

69 21

122 32

44 8

63 7 NS

90 17 <0.05

153 19 <0.05

42 5 NS

Patients 0.19 0.20 0.37 0.34 0.28 0.26 0.18 0.14 0.16 0.18

0.27 0.50 0.50 0.56 0.38 0.53 0.31 0.29 0.37 0.46

0.93 1.24 0.19 0.43 <0.02

3.0 4.0 1.3 1.9 <0.05

0.23 0.41 0.08 0,11 <0.001

1.26 0.17 <0.001 NS

4.5 0.5 <0.01 NS

0.46 0.19 <0.01 NS

DISCUSSION

In patients with extensive skin diseases, including erythrodermic psoriasis, a shift of fluid from the intra- to the extravascular spaces leading to an interstitial edema has been described. 1~ This altered distribution of ECV was attributed to an increased capillary surface area and/or a change in hydrodynamic conductivity of the capillary wall. Similar changes of the body fluids were found in our study. In patients with psoriasis the transepidermal water loss is increased, 1~but as ECV is not reduced, an increased transepidermal water loss must have been compensated. Previous studies have shown that hypoalbuminemia and increased microvascular leakiness to albumin are regular findings in patients with extensive skin disease, s'4 Our data demonstrate that a less disseminated skin disease might induce the same alterations. In previous works, ~'16 a minor but not significant increase in TERa~b was found in patients with varying degrees of psoriasis. It was, however, pointed out that a localized leakage from the psoriatic skin vessels might not alter the

Mean +_S.D.

Controls[] Mean -S.D. p

*Intravascular mass of albumin. tExtravascular mass of albumin. *Total albumin mass. §Distribution of intravaseular to total mass of albumin. I[Values from Rossing N, Worm A-M: Clin Physiol 1:275, 1981.

TERalb, which is a measure of the whole body escape rate of albumin from the total microvasculature. In the present study the TERatb is correlated to the area of involved skin (Table I). The discrepancy to the previous studies might be ascribed to differences in the activity of the psoriatic lesions. Electron microscopic studies have shown open interendothelial cell gaps in the skin vessels of involved and uninvolved psoriatic skin. 1 In a later report by the same group, a large venous capillary component characterized by a multilaminated basement membrane and a fenestrated endothelium was described in the capillary loops of involved psoriatic skin. 17 It has been suggested that an increased vascular permeability is present in the skin of psoriatic patients, 1but functional studies of this kind have not been reported previously. By combining the suction blister technic with tracer protein studies, it is possible to quantitate a local leakiness of the skin mierovasculature. 6'~s Our data show a two- to threefold increase in tracer albumin accumulation rate in the blister fluid from involved psoriatic skin as compared to uninvolved and normal skin. Corresponding to this increased leakiness, we found a higher concentration of endogenous plasma proteins in blister fluid from invoNed skin as compared to uninvolved skin of the patients. These data support the

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Staberg et al

proposed increased vascular permeability of involved psoriatic skin, and thus the increased TERalb could be accounted for by the increased leakiness of the involved skin microvasculature. The vessels of uninvolved psoriatic skin seem, however, to have a normal outflux of albumin, The approximate calculations of the intra- and extravascular masses of albumin 13 indicated an equally reduced IVM and EVM, and hence the total mass of albumin in the patients was reduced (Table III). The decreased mass of total body albumin may be a result of an increased fractional catabolism of endogenous albumin, caused by the increased microvascular albumin leakage as in other patients with hypoalbuminemia. 19'2° The subnormal albumin concentration in blister fluid of uninvolved skin thus reflects the decrease in total albumin mass. In blisters of involved skin the albumin concentration is higher than in uninvolved skin due to the increased albumin leakage, but still at a lower level than the control value due to the reduction in total albumin mass. Similar, but less pronounced, variations are found in the other plasma protein concentrations, and, incidentally, the concentrations in involved psoriatic skin are equal to those found in blisters of normal control skin (Table II). The relative distribution of albumin within and outside the vascular system is within normal range, so the increased vascular leakage of albumin might be compensated by an equally increased lymphatic return of albumin. This is in line with histologic investigations demonstrating a highly developed lymphatic system in psoriatic skin.l In a preliminary study, we have found an increased albumin clearance from involved psoriatic skin due to an increased lymphatic return. 21 In a recent paper, the influence of Goeckerman and PUVA treatments on the fine structure of the capillary loops and the labeling index of the basal cells of the epidermis was evaluated in patients with psoriasis. ~2 It was doubted that epidermal hyperplasia might be initiated by a protein-rich exudate in the underlying papillae through venous capillaries, as previously suggested, 2a Furthermore, the response to PUVA and Goeckerman therapies appeared to be mediated through the

Journal of the American Academy of Dermatology

microvasculature rather than through a direct antiproliferative effect on the basal cells. By using the method described in our study, it might be possible to quantitate the influence o f different treatment modalities on the leakiness o f psoriatic skin vessels and thereby further reveal the pathophysiologic role o f the vascular system in the development and resolution of psoriasis. REFERENCES 1. Braverman IM, Yen A: Microcirculation in psoriatic skin. J Invest Dermatol 62:493-502, 1974. 2. Rothschild MA, Bauman A, Yalow RS, Berson SA: Tissue distribution of 1t~1 labeled human serum albumin following intravenous administration. J Clin Invest 34:1354-1358, 1955. 3. Marks J, Shuster S: Method for measuring capillary permeability and its use in patients with skin disease. Br Med J 2:88-90, 1966. 4. Parring HH, Worm A-M, Rossing N: Plasma volume, intravascular albumin and its transcapillary escape rate in patients with extensive skin disease. Br J Dermatol 95:519-524, 1976. 5. Worm A-M, Rossing N: Transcapillary escape rate of albumin and plasma volume in patients with varying degrees of psoriasis. Br J Dermatol 97:423-427, 1977. 6. Worm A-M: Exchange of macromoleeules between plasma and skin interstitium in extensive skin disease. J Invest Dermatol 76:489-492, 198 I. 7. Ladegaard-Pedersen HJ: Measurement of extracellular volume and renal clearance by a single injection of inulin. Scand J Clin Lab Invest 29:145-153, I972, 8. Parving HH, Gyntelberg F: Transcapillary escape rate of albumin and plasma volume in essential hypertension. Circ Res 32:643-651, 1973. 9. Nosslin B: Determination of clearance and distribution volume with the single injection technique. Acta IVied Scand 442:97-101, 1965. 10. Bojesen E: A method for determination of inulin in plasma and urine. Acta Med Scand 266:275-282, 1952. 11. Kiistala U: Suction blister device for separation of viable epidermis from dermis. J Invest Dermatol 50: 129-137, 1968. 12. Mancini G, Carbonara AO, Heremans JF: Immunochemical quantitation of antigens by single radial immunodiffusion, lmmunochemistry 2:235-254, 1965. 13. Rossing N, Worm A-M: Interstitial fluid: Exchange of macromolecules between plasma and skin interstitium. Clin Physiol 1:275-284, 1981. 14. Worm A-M, Parving HH: Plasma and interstitial fluid volume in extensive skin disease. J Invest Dermatol 76:108-109, 1981. 15. Grice KA, Bettley FR: Skin water loss and accidental hypothermia in psoriasis, ichthyosis, and erythrodemla. Br Med J 4:195-198, 1967. 16. Worm A-M: Microvascular ieakage of plasma proteins after short-term PUVA treatment. J Invest Dermatol 74:158-160, 1980.

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Transvascular transport and distribution in psoriasis

17. Braverman IM, Yen A: Ultrastructure of the capillary loops in the dermal papillae of psoriasis. J Invest Dermatol 68:53-60, 1977. 18. Staberg B, Worm A-M, Brodthagen H, Rossing N: Direct and indirect effects of UVA on skin vessel leakiness. J Invest Dermatol. (In press.) 19. Worm A-M, Taaning E, Rossing N, Parving HH, Clemmensen OJ: Distribution and degradation of albumin in extensive skin disease. Br 3 Dermatol 104:389396, 1981. 20. Parving H-H, Rossing N, Jensen HA: Increased metabolic turnover rate and transcapillary escape rate of al-

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bumin in essential hypertension, Circ Res 35:544-552, 1974. 21. Staberg B, Worm A-M, Aasted M, Klemp P, Lundb P: The interstitial clearance of albumin from psoriatic skin. Clin Physiol 1:605, 1981. 22. Braverman IM, Sibley J: Role of the microcirculation in the treatment and pathogenesis of psoriasis. J Invest Dermatol 78:12-17, 1982. 23. Pinkus H, Mehregan AH: The primary histologic lesion of seborrheic dermatitis and psoriasis, J Invest Dermato[ 46:109-116, 1966.