Hidradenitis suppurativa: evidence for a bactericidal defect correctable by cholinergic agonist in vitro and in vivo

Cholinergic System and Its Therapeutic Importance in Inflammation and Autoimmunity

Neurological and immunological signals constitute an extensive regulatory network in our body that maintains physiology and homeostasis. The cholinergic system plays a significant role in neuroimmune communication, transmitting information regarding the peripheral immune status to the central nervous system (CNS) and vice versa. The cholinergic system includes the neurotransmitter\ molecule, acetylcholine (ACh), cholinergic receptors (AChRs), choline acetyltransferase (ChAT) enzyme, and acetylcholinesterase (AChE) enzyme. These molecules are involved in regulating immune response and playing a crucial role in maintaining homeostasis. Most innate and adaptive immune cells respond to neuronal inputs by releasing or expressing these molecules on their surfaces. Dysregulation of this neuroimmune communication may lead to several inflammatory and autoimmune diseases. Several agonists, antagonists, and inhibitors have been developed to target the cholinergic system to control inflammation in different tissues. This review discusses how various molecules of the neuronal and non-neuronal cholinergic system (NNCS) interact with the immune cells. What are the agonists and antagonists that alter the cholinergic system, and how are these molecules modulate inflammation and immunity. Understanding the various functions of pharmacological molecules could help in designing better strategies to control inflammation and autoimmunity.

Hidradenitis Suppurativa

Background:

Hidradenitis suppurativa is a clinically defined disease that causes considerable morbidity for patients. The results of recent studies, which have increased the understanding of this disease, are reviewed.

Objective:

The epidemiology, risk factors, pathogenesis, and treatment of this disease are summarized to help clinicians with practical patient management.

Conclusion:

Hidradenitis suppurativa remains a clinical challenge to patients and physicians alike. Physicians should be familiar with the impact this disease has on the patient and with the range of treatments available. Use of simple incisions as treatment is strongly discouraged. Additional pathogenic as well as therapeutic studies are necessary.

Comorbidities of hidradenitis suppurativa (acne inversa)

Comorbidities of hidradenitis suppurativa (acne inversa) were reviewed by extracting original and review publications included in MEDLINE, EMBASE and COCHRANE libraries using the terms "hidradenitis," "Verneuil" and "acne inversa." Follicular occlusion disorders, inflammatory bowel diseases, especially Crohn disease, spondylarthropathy, other hyperergic diseases, genetic keratin disorders associated with follicular occlusion and squamous cell carcinoma were the most common hidradenitis suppurativa comorbid diseases. A first classification of these major comorbidities and their possible genetic background reveals a list of chromosome loci and genes, which could be hidradenitis suppurativa candidates. Most of these diseases belong to the group of autoinflammatory disorders, where th17 cell cytokines seem to play a central role.

Altered innate and adaptive immune responses in patients with hidradenitis suppurativa

BACKGROUND

The clinical improvement of hidradenitis suppurativa reported in a small number of patients with antitumour necrosis factor (anti-TNF)-alpha therapies supports the hypothesis for an altered immune response in these patients.

OBJECTIVES

To evaluate the state of the innate and adaptive immune responses in patients with hidradenitis suppurativa.

METHODS

Fifty-three patients and six healthy controls were studied. Blood was sampled and subpopulations of lymphocytes were analysed by flow cytometry; monocytes were isolated and their function was evaluated from the concentrations of TNF-alpha and interleukin (IL)-6 in supernatants of cell cultures after triggering with endotoxins (lipopolysaccharides). TNF-alpha and IL-6 were estimated by an enzyme immunoassay.

RESULTS

CD3/CD8 lymphocytes were lower in patients with involvement of the perineum than in controls; patients with involvement of the breast had higher levels of natural killer (NK) cells than controls. A negative correlation was found between years lapsing since initial presentation of lesions of hidradenitis and the percentage of NK cells. Monocytes isolated from healthy volunteers were more active for the secretion of TNF-alpha and IL-6 than those of patients with hidradenitis suppurativa.

CONCLUSIONS

A reduction in the percentage of NK cells over time and a lower monocyte response to triggering by bacterial components is observed in patients with hidradenitis suppurativa. Further research is needed to clarify if these changes are connected to an autoimmune mechanism in the pathogenesis of hidradenitis suppurativa.

Acne inversa (alias hidradenitis suppurativa)

Acne inversa is a recurrent, suppurative disease manifested by abscesses, fistulas, and scarring. Once considered to be a disease of the apocrine glands, it is actually a defect of follicular epithelium. Thus, the term hidradenitis suppurativa is a misnomer and should be abandoned. In cases of familial acne inversa, the pattern of transmission and number of affected individuals are consistent with autosomal dominant inheritance. Aetiological factors such as hyperandrogenism, obesity, smoking and chemical irritants are not consistently associated with the affection. Bacterial involvement is not a primary event in acne inversa, but is secondary to the disease process. Potential complications include dermal contraction, local or systemic infection due to the spread of microorganisms, systemic amyloidosis, arthropathy, and squamous cell carcinoma. As spontaneous resolution is rare and progressive disability is the rule, early definitive surgical intervention is advisable. The surgical procedure of choice in most cases is wide local excision and healing by secondary intention. Pharmacotherapeutic drugs, including synthetic retinoids and antiandrogens, do not prevent progression of the disease.

Hidradenitis suppurativa polyposa

A case of severe chronic hidradenitis suppurativa of the perineum complicated by disfiguring fibrous, polypoid lesions is presented. The patient, a 41-year-old woman, had a long history of axillary hidradenitis which subsequently involved the perineum. Draining sinuses, scars and large pendulous masses of the vulva developed over 10 years. Cutaneous scars, ridges, papules and large fibrous polyps were present. Deep clefts, sinuses, dense fibrous scars and foci of chronic inflammation were seen. Rarely, large fibrous polyps may develop in chronic hidradenitis suppurativa and may be due to chronic local lymphedema. Careful pathologic examination is necessary to exclude squamous cell carcinoma.

Mycobacterium fortuitum infection: evidence of bactericidal defect due to hyperactive antigen-specific suppressor cells. Correction in vitro and in vivo by cholinergic agonist and indomethacin

Immunologic studies in a patient with long-standing Mycobacterium fortuitum infection revealed normal numbers of T cells, T inducers, T suppressors, B cells, and monocytes, significant in vitro proliferative response to M. fortuitum antigen, and poor bactericidal activity against M. fortuitum but not against Escherhicia coli. M. fortuitum antigen-activated suppressor cells contributed to the bactericidal defect. The activity of these suppressor cells could be eliminated by the in vitro treatment of blood mononuclear cells with a combination of a cholinergic agonist and indomethacin, but not with either alone. Administration of the two drugs to the patient resulted in reversal of the bactericidal defect and dramatic clinical improvement. Systemic atypical (nontuberculous) mycobacterial infection may activate specific suppressor cells that could compromise the host's phagocytic cell function. Modulation of those suppressor cells by a combination of a cholinergic agonist and prostaglandin synthetase inhibitor could reverse this abnormality and may be beneficial to the patient.