Pathogenesis and treatment of Raynaud's phenomenon

Part II: The treatment of primary and secondary Raynaud's phenomenon

Raynaud phenomenon (RP) presents with either primary or secondary disease, and both have the potential to negatively impact patient quality of life. First-line management of RP should include lifestyle modifications in all patients. Some patients with primary RP and most with secondary RP require pharmacologic therapies, which may include calcium channel blockers, topical nitrates, phosphodiesterase 5 inhibitors, or endothelin antagonists. Additional approaches to treatment for those with signs of critical ischemia or those who fail pharmacologic therapy include botulinum toxin injection and digital sympathectomy. Herein, we describe in detail the treatment options for patients with RP as well as provide treatment algorithms for each RP subtype.

Raynaud's phenomenon and related vasospastic disorders

Raynaud's phenomenon, which is characterized by episodic digital pallor, cyanosis and rubor upon exposure to cold environment or to stress, is relatively common, although the prevalence depends on the climate. Still, it is under-diagnosed, under-treated, and often confused with other conditions. Primary Raynaud's phenomenon (i.e., Raynaud disease) must be distinguished from secondary Raynaud's phenomenon (i.e., Raynaud syndrome) as long-term morbidity and outcomes differ vastly between the two conditions. Additionally, the practitioner must differentiate between Raynaud's phenomenon and related vascular disorders, such as acrocyanosis, pernio, and livedo reticularis. In this article, we review differences between the conditions and suggest an approach to diagnosis and treatment strategy for these disorders.

Partial agonist activity of α1-adrenergic receptor antagonists for chemokine (C-X-C motif) receptor 4 and atypical chemokine receptor 3

We observed in PRESTO-Tango β-arrestin recruitment assays that the α₁-adrenergic receptor (AR) antagonist prazosin activates chemokine (C-X-C motif) receptor (CXCR)4. This prompted us to further examine this unexpected pharmacological behavior. We screened a panel of 14 α_1/2- and β_1/2/3-AR antagonists for CXCR4 and atypical chemokine receptor (ACKR)3 agonist activity in PRESTO-Tango assays against the cognate agonist CXCL12. We observed that multiple α₁-AR antagonists activate CXCR4 (CXCL12 = prazosin = cyclazosin > doxazosin) and ACKR3 (CXCL12 = prazosin = cyclazosin > alfuzosin = doxazosin = phentolamine > terazosin = silodosin = tamsulosin). The two strongest CXCR4/ACKR3 activators, prazosin and cyclazosin, were selected for a more detailed evaluation. We found that the drugs dose-dependently activate both receptors in β-arrestin recruitment assays, stimulate ERK1/2 phosphorylation in HEK293 cells overexpressing each receptor, and that their effects on CXCR4 could be inhibited with AMD3100. Both α₁-AR antagonists induced significant chemical shift changes in the ¹H-¹³C-heteronuclear single quantum correlation spectrum of CXCR4 and ACKR3 in membranes, suggesting receptor binding. Furthermore, prazosin and cyclazosin induced internalization of endogenous CXCR4/ACKR3 in human vascular smooth muscle cells (hVSMC). While these drugs did not in induce chemotaxis in hVSMC, they inhibited CXCL12-induced chemotaxis with high efficacy and potency (IC₅₀: prazosin—4.5 nM, cyclazosin 11.6 pM). Our findings reveal unexpected pharmacological properties of prazosin, cyclazosin, and likely other α₁-AR antagonists. The results of the present study imply that prazosin and cyclazosin are biased or partial CXCR4/ACKR3 agonists, which function as potent CXCL12 antagonists. Our findings could provide a mechanistic basis for previously observed anti-cancer properties of α₁-AR antagonists and support the concept that prazosin could be re-purposed for the treatment of disease processes in which CXCR4 and ACKR3 are thought to play significant pathophysiological roles, such as cancer metastases or various autoimmune pathologies.

[The effects of diosmin and hesperidin on capillary blood flow of upper limbs in patients with secondary Raynaud's syndrome]

The article discusses the effects of diosmin and hesperidin on capillary blood flow in patients with secondary Raynaud's syndrome (RS). Raynaud's syndrome a difficult problem of modern angiology, since in its development there is a large range of disorders of the capillary blood flow of the limbs. Currently, the main way of therapy in patients with secondary Raynaud's syndrome is the use of either calcium channel blockers (if angiospastic stage of the disease), or prostaglandins of group E1 (with tropho-paralytic stage of secondary RS). However, pharmacological effects of calcium channel blockers (vasodilation) and prostaglandins (vasodilation, antiproliferative, anti-inflammatory etc.) do not allow impact on all violations of capillary blood flow, occurs when the Raynaud's syndrome. In this regard, the task was to study the reaction of capillary blood flow of the fingers of the hands on the concomitant use of drugs based on diosmin and hesperidin. A prerequisite for the use of a combination of diosmin and hesperidin in the treatment of RS was based on data about their impact on the state of the venous segment of the capillary bed and perivascular oedema. To conduct the study was established two groups of patients (22 in each group). The main criterion for inclusion of patients in the study was the presence of newly identified Raynaud's syndrome of angiospastic or tropho-paralytic stage of the disease. The main exclusion criteria was the presence of necrotic stage of the disease. In the first group of patients therapy was carried out using only vasodilators. In the second group (comparison group) with the addition of a combination of diosmin and hesperidin (tablets Venarus used in a dose 500 mg 2 times per day). The condition of capillary blood flow in this study was estimated by the method of videocapillaroscopy (VCS). Statistical data processing was performed using a criterion of statistical significance (P-value). The study revealed the significant impact of a combination of diosmin and hesperidin for parameters of capillary blood flow that correlated with clinical improvements - reduction of oedema of the fingers of the hands.

Guillain-Barré syndrome presenting with Raynaud's phenomenon: a case report

Background

Guillain–Barré syndrome is an immune mediated acute inflammatory polyradiculo-neuropathy involving the peripheral nervous system. Commonest presentation is acute or subacute flaccid ascending paralysis of limbs. Rarely autonomic dysfunction can be the presenting feature of Guillain–Barré syndrome. Raynaud’s phenomenon, although had been described in relation to many disease conditions, has not been described in association with Guillain–Barré syndrome up to date.

Case presentation

We report the first case of Guillain–Barré syndrome presenting with Raynaud’s phenomenon in a 21-year-old previously well boy. New onset Raynaud’s phenomenon was experienced followed by acute ascending flaccid paralysis of lower limbs and upper limbs together with palpitations and postural giddiness. Nerve conduction studies showed acute inflammatory demyelinating polyneuropathy with cerebrospinal fluid cyto-protein dissociation. He was treated with intravenous immunoglobulin and showed a satisfactory clinical recovery of muscle weakness, Raynaud’s phenomenon and autonomic disturbances.

Conclusion

Guillain–Barré syndrome presenting with Raynaud’s phenomenon is not being reported in literature previously. Although the underlying mechanism is not fully understood, Raynaud’s phenomenon should prompt the physician to consider Guillain–Barré syndrome with a complimentary clinical picture.

Thermographic parameters in the diagnosis of secondary Raynaud's phenomenon

OBJECTIVE

To determine the major infrared thermographic parameters in discriminating between patients with and without secondary Raynaud's phenomenon.

DESIGN

A cross-sectional study.

SETTING

Outpatient clinic of a university department of physical medicine and rehabilitation in Vienna.

PATIENTS

Consecutive sample of 86 patients (72 women, 14 men) referred from the Division of Rheumatology for the clarification of a possible secondary Raynaud's phenomenon.

MAIN OUTCOME MEASURES

According to color changes induced by cold exposure, clinical classification of Raynaud's phenomenon was performed as follows: no, unlikely, probable, and definite Raynaud's phenomenon. The following thermographic parameters were applied to a stepwise logistic regression analysis: the absolute temperature of the fingertips before, 10, and 20 minutes after cold challenge (Tpre, T10, T20); the longitudinal temperature difference before, 10, and 20 minutes after cold challenge (LTDpre, LTD10, LTD20); the mean area under the rewarming curve of the fingertips; the recovery index 20 minutes after cold challenge (RI20); and the most rapid phase of rewarming of the fingertips of both hands (Gmax right, Gmax left). The sensitivity of thermographic classification into the 4 groups of clinical evaluation was assessed by discriminant analysis using significant parameters from logistic regression analysis.

RESULTS

Only LTDpre reached the level of significance (p < .0001). Using LTDpre, 22 of 23 subjects without clinical Raynaud's phenomenon and 20 of 26 patients with definite clinical Raynaud's phenomenon were classified correctly. Patients with unlikely or probable Raynaud's phenomenon were classified as no Raynaud's phenomenon or definite Raynaud's phenomenon.

CONCLUSION

LTDpre is the major thermographic parameter to discriminate between patients with and without definite Raynaud's phenomenon by clinical history.

Effect of cooling on cutaneous microvascular adrenoceptors in vivo in the rabbit ear

Previous studies have suggested that moderate cooling increases the responsiveness of vascular alpha2-adrenoceptors. However, limited information is available documenting the influence of temperature changes on adrenoceptor responses in the microvasculature of thermoregulatory organs (e.g., the human digit and the rabbit ear) subjected to a wide range of temperatures. In the present study, the effect of local cooling (24 degrees C) on cutaneous microvascular adrenoceptors in the ear was observed in vivo in male New Zealand White rabbits (total: 66 ears). The rabbit ear was studied in a temperature-controlled tissue bath; the ear preparation was pretreated with terazosin (an alpha1-adrenoceptor antagonist) (10(-5) M) or a combination of terazosin (10(-5) M) and propranolol (a beta-adrenoceptor antagonist) (10(-6) M). The microvascular diameter responses of the ear to norepinephrine (10(-11)-10(-4) M) then were determined at 24 or 34 degrees C, respectively, to determine the influences of low temperature on adrenoceptor responses to norepinephrine stimulation. The results demonstrated that low concentrations of norepinephrine induced vasodilation in arterioles and arteriovenous anastomoses. This vasodilation was followed by vasoconstriction with an increased concentration of norepinephrine in animals with alpha1-adrenergic blockade at 34 degrees C. Moderate tissue cooling increased the microvascular maximal response of the rabbit ear to norepinephrine and abolished the vasodilatation induced by a low concentration of norepinephrine. There was no significant difference in the microvascular response to norepinephrine between the two temperature conditions after simultaneous blockade of alpha1-adrenoceptors and beta-adrenoceptors. Data from the present study indicate that moderate cooling does not enhance the responsiveness of alpha2-adrenoceptors to norepinephrine. In contrast, cooling reduced the beta-adrenergic activity of arterioles and arteriovenous anastomoses after norepinephrine stimulation.

Primary Raynaud's phenomenon. Age of onset and pathogenesis in a prospective study of 424 patients

Many authors consider that late onset is a suspect criterion for differentiating primary Raynaud's phenomenon (Raynaud's disease, RD) from Raynaud's syndrome (RS). However, many cases of late-onset Raynaud's phenomenon in patients over forty years of age remain without etiologic diagnosis and therefore deserve the designation "late-onset RD." One hundred and ninety-four patients with RD (143 women, 51 men) were selected among 424 patients with Raynaud's phenomenon, according to Allen and Brown's criteria with negative serologic investigations and normal capillaroscopy. The purpose of the study was to consider the possible discriminant value of age of onset in distinguishing between RD and RS. The following epidemiologic features were studied: age of onset, sex, family history of Raynaud's phenomenon and migraine, and smoking and working habits. Microcirculation was assessed by capillaroscopy and strain-gauge plethysmography. Maximal digital flow at 45 degrees C and reactivity to cold were determined for each patient. Results were related to age of onset. The existence of true cases of late-onset RD in patients over forty years of age was confirmed (prevalence 27%), showing a correlation with a family history of Raynaud's phenomenon inferior to that found in early-onset cases (p < 0.0001). Microcirculation studies generally indicated a strong correlation between reactivity to cold, familial RD, and early onset, whereas no correlation was found with migraine or smoking. Nor was there any clinical or plethysmographic evidence for arteritis as a possible pathogenetic factor in late-onset RD. These results indicate that late-onset RD is a valid designation and that its pathogenesis seems less dependent on genetic sensitivity to cold than that of early-onset cases. In the absence of underlying arteritis, neurovascular dysfunction or a hemorheologic mechanism may be suggested as plausible causes of late-onset RD.

Raynaud's syndrome, an enigma after 130 years

The recent literature concerning Raynaud's syndrome is reviewed. Raynaud's syndrome is as common as hypertension and diabetes. In spite of its generally benign character, it causes a lot of discomfort to individuals and sickness absenteeism to society, especially in the colder regions of the world. The etiology remains an enigma 130 years after its first description, perhaps even more so than ever before, the many new theories proposed in the literature. Clearly, in a condition where seventy different etiologic theories are advocated, the culprit lesion is obviously missing, or there is not a culprit lesion but an accumulation of conditions having nothing in common but a few symptoms. Moreover a Raynaud attack may result, not from a single event, but from a cascade of events, just as, for example, hemostasis does. Controversy about diagnosis exists all over. For example, how does one make a diagnosis? Patient history has been considered unreliable. A standardized cold test, though highly reproducible in the authors' hands, is far from common property. Raynaud's syndrome is a condition for which thirty-eight therapies have been advocated in the last three years, but the curative answer is still to come.